Con tents · UK ISSN 0032-1400 PLATINUM METALS REVIEW A quarterly survey of research on the platinum metals and of developments in their application in industry VOL. 20 OCTOBER 1985

UK ISSN 0032-1400

PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their application in industry

VOL. 20 OCTOBER 1985 NO. 4

Con tents

Ruthenium Catalyst Systems for the Production of Hydrocarbons from Coal

An Organometallic Chemistry Monograph

The Corrosion Behaviour of Objects Electroplated with Platinum

Symposium on Fine Chemical Manufacture

Automobile Exhaust Emissions Control

Space Station Auxiliary Propulsion Jets

A Standard PlatinudSilica Catalyst

The Production of Palladium Powders for Electronic Applications

Oxygen Probe for Heat-Treatment Furnaces

The First Experiments on Platinum

Abstracts

New Patents

Index to Volume 29

'46

'54

' 5 5

162

'63

'67

168

'75

'79

I 80

185

191

196

Communications should be addressed to The Editor, Platinum Metals Rev&

.johnson Matthey Public Limited Company, Hatton Garden, London EClN BEE

Ruthenium Catalyst Systems for the Production of Hydrocarbons from Coal RECENT STUDIES ON THE FISCHER-TROPSCH REACTION

By F. King, E. Shutt and A. I. Thornson Johnson Matthey Technology Centre

A new catalyst with a low metal loading has been developed for the Fischer-Tropsch synthesis, and has shown good activity, selectivity and durability in laboratory reactors, demonstrating that these catalyst systems could be used in future commercial processes.

Although in the short term crude oil is in plentiful supply, mainly as a consequence of decreased demand resulting from the worldwide recession, it should not be forgotten that, based on existing knowledge, the estimated reserves of oil are only sufficient to sustain supplies into the early decades of the next century. Currently, crude oil is the mainstay of the chemical economy and in the free market economy countries of the world it accounts for 98 per cent of the energy used in transportation and 85 per cent of the sources of chemical feedstocks. The remaining 1 5 per cent of chemical feedstock is natural gas and this can be expected to play an increasingly important role as the reserves of crude oil decrease. In addition, there are vast reserves of coal and many research workers have investigated the possibility of converting it into the liquid hydrocarbons currently produced from oil.

In general, coal is much more difficult to process than crude oil or natural gas and hence it is more expensive to convert into useful products. Attempts to synthesise liquid hydrocarbons have been based primarily upon either direct coal liquefaction or gasification to carbon monoxide and hydrogen (syngas) for use in the Fischer-Tropsch synthesis.

In the direct liquefaction of coal it is necessary to increase the hydrogen:carbon ratio in order to transform the coal into oil. This is achieved by the hydrogenation of pulverised

coal in a suitable solvent in the presence of a catalyst and at high pressures. The liquid products resulting from the hydrogenation of coal are significantly different from those of naturally occurring petroleum. The middle distillates from the coal derived liquids are highly aromatic materials compared with the equivalent oil derived products. This high aromaticity is suitable for use as petrol but it makes the middle distillates of coal liquids unsuitable for the production of jet fuel and diesel oil.

The alternative processes for the production of liquid hydrocarbons are based on the gas- ificatiodFischer-Tropsch route. Coal is reacted at elevated temperatures with oxygen and steam to produce carbon monoxide and hydrogen which, after purification, are then reacted together in the presence of a suitable catalyst to synthesise a range of hydrocarbons. This synthesis is known as the Fischer-Tropsch reaction and is the subject of this article, which includes a description of advances that have been made during research work carried out at the Johnson Matthey Technology Centre.

Process Developments The history of the Fischer-Tropsch process

goes back to 1902 when Sabatier and Senderens observed that methane could be formed by reacting carbon monoxide and hydrogen together in the presence of a nickel or cobalt

Platinum Metals Rev., 1985,29, (4), 146-154 146

catalyst (I). The hydrocarbon growth mechanism was first studied in 1923 when Fischer and Tropsch discovered that a range of liquid hydrocarbons and oxygenated products could be produced from syngas over iron and cobalt catalysts (2).

CO+ZH, + (-CH,-)+H,O AHR=- 165.5 kJ

Further developments took place in Germany, Japan and elsewhere, and the first four commercial plants were commissioned in Germany in 1936. By 1944 nine cobalt based units were in operation in Germany with a total capacity of approximately 700,000 tons per year.

After the second world war several com- panies in the United States of America deve loped new r e a c t o r s f o r t h e Fischer-Tropsch process. However, the next major commercial exploitation of the process did not occur until 1955. In that year an iron-potassium based plant was commissioned by the South African Coal, Gas and Oil Corporation (SASOL). Two types of reactor were used: a fixed bed tubular (Arge) reactor and a circulating fluidised bed (Synthol) reactor. This

plant has operated successfully up to the present day.

Following the development in the 1950s of the large oil deposits in the Middle East, interest in the Fischer-Tropsch process declined. However, a resurgence occurred following the Middle East oil crisis in 1973 and this resulted in SASOL constructing two, additional much larger plants: SASOL I1 and SASOL IIL The first of these plants was commissioned in 1980 and both plants are in operation today employing an iron catalyst in Synthol reactors. Typical examples of the product spectrum produced by the SASOLre- actors are given in Table I. Despite the recent fall in oil prices the SASOL plants still continue to be commercially viable, primarily due to the availability of vast reserves of coal.

Fischer-Tropsch Selectivity So far the only metals to achieve commercial

significance in catalysing Fischer-Tropsch processes have been cobalt and iron; however, other metals are active as catalysts, and ruthenium is perhaps intrinsically the most active for the hydrogenation of carbon monoxide (3, 4, 5) . Ruthenium could be very

~~

Table I

Product Selectivities of SASOL Commercial Reactors ( 12)

Product

CH4 CZH, CZH, C3H6 C3H8 C4H8

C, to C,, (Gasoline) C,, to C,, (Diesel)

Cz4 to C,, (Medium wax) =- C3, (Hard wax) Water soluble non-acid chemicals Water soluble acid

C4H10

Cl, to c23

~ ~ ~

Composition, percentage carbon atom

Fixed bed at 493 K

2.0 0.1 1.8 2.7 1.7 3.1 1.9

18 14

7 20 25

3.0 0.2

Synthol at 598 K

10 4 4

12 2 9 2

40 7

4

5 1

Platinum Metals Rev., 1985,29, (4) 147

important in the future because in addition to its high intrinsic activity it is selective for the formation of higher molecular weight products ( 5 ) . 'l'hese higher molecular weight straight- chain products are premium paraffinic materials, which are ideal for use as jet and diesel fuels. 'rhus it is not surprising that ruthenium continues to attract considerable research attention (6- 10).

However, in the assessment of any potential Fischer-Tropsch catalyst it should be borne in mind that the reaction is essentially a polymerisation process and that the product spectrum can only be adjusted within certain limits. It has been found that for a given product distribution the quantity of one particular carbon nurnber species is fixed, and that if the selectivity to this species is altered then the selectivities to all the other species will shift in a predictable ratio ( I I ) . This relationship has been shown to hold irrespective of the means by which the selectivity shift was brought about, that is whether resulting from a change in the process operating conditions or by a change in catalyst formulation ( I 2). The selectivities of the products at either end of the

spectrum, namely methane and hard wax, can attain very high values but all the intermediate products can only reach limited maximum values.

Although there are several proposed mechanisms for the Fischer-Tropsch synthesis ( I 3) all assume the growth of carbon chains in a stepwise process. The product distribution is usually described by the Flory equation as modified by Schulz ( I 4):

K' "=nu "-1 ( I -u)2 (i)

where n represents the product carbon number, W, the weight fraction of carbon number n, and a the chain growth probability factor. The chain length selectivity as predicted by the Schulz-Flory model is shown in Figure I . The distribution curves for alcohols or alkenes are similar to those illustrated for the hydrocarbons. 'I'he model has its limitations and attempts have been made to improve the fit with experimental data by steadily increasing a between certain limits.

'l 'hus, any catalyst used in the Fischer-Tropsch synthesis will produce a broad spectrum of hydrocarbon chain lengths, with

0.1 a2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 PROBABILITY OF CHAIN GROWTH

Fig. 1 The Fischer-Tropsch r e a c t i o n p r o d u c e s a product range that can be described by the Schulz- Flory equat ion. One important conclusion of this model, which has been observed in practice, is that any particular carbon chain length can only achieve a certain maximum in selectivity. After (12)

Platinum Merals Rev., 1985,29, (4) 148

yields described intrinsically by the Schulz- Flory equation. However, individual metals will also produce varying amounts of branched alkanes, alkenes and carbonyl compounds, and the yields of these products can also be described by the Schulz-Flory model. Ruthenium is potentially superior to iron and cobalt because it is intrinsically more active and produces significantly less of the undesirable materials. Furthermore the metal has little, if any, water gas shift activity and only very small amounts of carbon dioxide are produced.

Until very recently the desired activity for a ruthenium catalyst could only be achieved with relatively high metal loadings but now a catalyst has been developed which under laboratory conditions has shown good activity and selectivity at a ruthenium metal content low enough to allow significant commercial use.

Laboratory Reactors The choice of laboratory reactors to

investigate the catalytic behaviour of the low metal loading ruthenium catalyst system was, to a large extent, determined by the type of reactor most likely to be used in a commercial process. Supported catalysts do not normally have sufficient attrition resistance to cope with a fluidised bed environment, as created by a Synthol reactor. Therefore the use of ruthenium in a fluidised bed reactor would be inappropriate, since economics dictate that the metal has to be supported in order to maximise its effectiveness. Another drawback of the Synthol reactor is its inability to deal with high molecular weight products such as wax. Conse- quently the use of ruthenium is probably limited to fixed bed tubular reactors similar to the Arge system operated by SASOh as shown in Figure 2.

Two types of reactor were chosen to simulate the behaviour of a catalyst in an Arge system, a Berty reactor and a fixed bed tubular reactor. The control equipment and pipework used with the Berty reactor were similar to those used for the fixed bed reactor (see Figure 3). The Berty reactor is an internal recycle reactor which can simulate the linear gas velocity experienced in

commercial processes. In effect the catalyst charge can be considered to be a small section through an Arge tube, and this reactor was used to determine the behaviour of the catalyst under a variety of operating conditions.

The tubular reactor used was of a conventional design and consisted of a 70 cm length of 0.9 cm internal diameter stainless steel tube; a schematic drawing of this e q u i p ment is shown in Figure 3. Since it was known that the tubular reactor was incapable of s i m u l a t i n g t h e h e a d m a s s t r a n s f e r characteristics of a commercial reactor its use was restricted to durability studies.

Variation of Operating Conditions The purpose of this work, carried out in the

Berty reactor, was to determine the sensitivity of the process to various operating parameters in order to help identify the conditions which

Steam Steam heater

Steam collector

outlet

Feed water inlet

ner shell Tube bund

Gas outlet

Wax outlet

Fig. 2 The SASOLArge reactor consists of more than 2,000 tubes 12 m long and with an internal diameter of 50 mm. The outside of the tubes is surrounded by boiling water and the reactor temperature is controlled by regulating the pressure. A high linear gas velocity ensures that the reactor operates under near isothermal conditions. After ( 12)


- I 1

I-

W U 30. e W

E W

e X g P z 0 10

m

I

CO conversion i20:A CH, selectivity

L 83 A r g m Hydrogen C a M .

monoxide

Fig. 3 The fixed bed reactor was designed to operate continuously over extended periods of time with the minimum of supervision. Gas flowrates, pressure and temperature were automatically controlled and gas and liquid hydrocarbon products were periodically removed from the collecting bottles. The exit gas was routinely monitored by on-line gas chromatography. This schematic gas diagram of the equipment shows the most important features of the reactor, namely: F1 to F4 mass flow sensors. PT1 to PT3 pressure transducers, B 1 to B3 product collection, G.C. gas chromatograph

could be used in a future commercial reactor. The effect of temperature on the perfor-

mance of the low metal loading ruthenium catalyst at 22 bar is illustrated in Fig. 4. As the temperature increased the conversion increased and so also did the selectivity to methane. However, up to 25oOC the selectivity to methane was still less than 5 per cent. Experi- mentally it was found necessary to operate the process below z5ooC in order to minimise deactivation of the catalyst by coke formation.

Increasing the reactor pressure had a beneficial effect not only in increasing the reaction rate but also in significantly decreasing the selectivity to methane. The results obtained for a catalyst at 2 I 0°C are also illustrated in Figure 4. The experimental data obtained during this experiment were also used to confirm the Schulz-Flory model. An examination of Equa- tion {i) shows that a plot of log (WJn) against n

- .

4 V

220 230 2 4 0 2 3 0 TEMPERATURE .C

20 40 60 PRESSURE I N BARS

Fig. 4 The Fischer-Tropsch reaction gives rise to a very broad range of hydrocarbon products. Consequently the quantification of the entire product spectrum is a formidable task. The behaviour of the catalysts under various operating conditions has been assessed by comparing performance in terms of the conversion of carbon monoxide and the selectivity to methane. Conditions 500 GHSV:H,; CO= 2: 1


should yield a straight line of slope log a. This has been confirmed in a number of the experiments and a reasonable fit to experimental data obtained. The entire product spectrum could then be described in terms of one number: the chain growth probability factor a.

Perhaps a more useful number which also uniquely describes the product distribution is the location of Nmu, the carbon chain length with the highest weight frequency. If Equation (i) is differentiated with respect to n and re- arranged it can be shown that Nmax and a are related by Equation (ii):

--I N max =- (ii)

This treatment was applied to the wax samples obtained during the pressure experiments, and Figure 5 shows the relationship obtained between N,,, and pressure. This Figure confirms the published trend, that the average product chain length increases with increasing pressure.

The above treatment assumed that a constant value of a existed over the carbon number range examined, but there exist some interesting variations in the value of a which are dependent upon the reactor used and these are described later.

In a

Conversion

Selectivity to wax

24.6 per cent

88.3 per cent

Selectivity to methane

I Selectivity to liquid 9.6 per cent I hydrocarbons

1.4 per cent

32.

31.

30. X

E 2*

28-

2 7-

2 6

2 5

'l'he effect of changes in the gas hourly space velocity (GHSV), that is the number of catalyst bed volumes of reactant which can be treated per hour, on the performance of a low metal loading catalyst has also been investigated. As the space velocity increased the conversion of carbon monoxide decreased and the selectivity to methane increased. The increase in methane selectivity can be explained in terms of a reduction in the residence time of the reactants on the catalyst surface.

'I'he hydrogen to carbon monoxide ratio was varied and the effects on catalyst activity and selectivity at 2iooC and 60 bar were established. Increasing the ratio of reactants caused a moderate increase in activity and a noticeable increase in methane selectivity. As might be expected, the alkane to alkene ratio in the liquid product also increases with an increase in the hydrogen to carbon monoxide ratio, but no effect on the selectivity to alcohols was observed.

A typical example of the kind of results that can be obtained with a low metal loading catalyst in the Berty reactor is given in Table 11. 'l'he example chosen was not the most active catalyst but one on which an accurate mass balance had been carried out, that is there was a good correlation between the total amount of reactant and products. The selectivity to wax is very high and the selectivity to methane exceptionally low. If required the wax may be

.


Kuthmium catalysed Fischet-Tmpseh Synthesis with 03% Ru/AI,O, Catalyst

in a Hrrty Hrac*lor*

Table II

*Conditions: 210'C. 60 bar, 500 GHSV, H,:C0=2:1

PRESSURE IN BARS Fig. 5 The average product chain l e n g t h o b t a i n e d d u r i n g t h e Fiseher-Tropsch synthesis increases with increasing pressure. This property has been quantified by plotting the relationship between N the carbon chain length with highest weight ire- quency, and the reactor pressure

Table 111

Character isat ion of Diesel f r o m Fixed Bed Reactor

Test Method Results

Cetane Indexla) Specific Gravity 6 0 to 6OoF API"'Gravity at 6OoF Cloud Point, OC

I.P. 218'b' I.P. 160 Conversion I.P. 219

7 8 0.7555

55.79 - 1 0

I I

la) Cetane Index is the percentage 01 cetane in a minure of cetane and I-methylnaphthalene that has the soma ignition quality as the oil under fast Ibl I.P. numbers correspond to standard institute of Petroleum Test procedures (c) American Petroleum Institute

hydrocracked back to maximise the diesel yield. The quality of wax was similar to that obtained in the durability trial.

Durability Trial The most effective utilisation of a noble

metal such as ruthenium is usually an essential prerequisite for its use in an industrial process. However, in general a prolonged operating time is preferable to a higher initial activity which decays rapidly. Consequently, having developed a very active low metal loading catalyst for the Fischer-Tropsch process it was necessary to determine how the catalyst would perform over a prolonged period of time. The trial was conducted in the fixed bed tubular reactor under conditions which were expected to produce reasonable quantities of wax and liquids. The catalyst was operated for more than 3,000

hours and its activity and selectivity to methane regularly monitored. The conversion observed levelled off at 25 per cent after 300 hours due to a wetting of the catalyst bed, and thereafter stayed virtually constant throughout the trial. Methane selectivity was relatively high compared with the Berty reactor but this was not surprising considering the nature of the tubular reactor. The wax was of excellent physical quality with a melting point in the range of 80 to I I o°C. The characterisation of this wax confirmed it to be a very high quality product, comprising straight chain alkanes with negligible quantities of branched chains or alkenes. Fig. 6 shows a typical chromatographic analysis of the liquid hydrocarbon product.

Once again the material is a high quality, pre- dominantly paraffinic product. Details of the characterisation of the liquid product which boils above 160OC are given in Tables I11 and IV. The very high cetane number of 78 (compared with commercial diesel of cetane number about 45) is very impressive.

Periodically, during the durability trial the product gas was analysed for carbon dioxide indicating that the selectivity to this product was never greater than 0.6 per cent.

The durability data demonstrate very satisfactorily that it is possible to operate the new low metal loading ruthenium catalyst to

Tabla IV

Character isat ion by Distillation According t o I.P. 123

OC

First boiling point 10 per cent recovered at 2 0 per cent recovered at 30 per cent recovered at 4 0 per cent recovered at 5 0 per cent recovered at 60 per cent recovered at 7 0 per cent recovered at 80 per cent recovered at 9 0 per cent recovered at Final boiling point

161.0 176.0 188.0 199.0 2 10.0 221.5 233.0 246.5 262.0 282.5 303.0

Recovery, volume per cent 97.5 Residue, volume per cent 2.5


Fig. 6 The liquid hydrocarbon product obtained with ruthenium is a premium quality paraffinic material. Virtually no chain branching occurs and very little oxygenated products are produced. This gas liquid chromatogram shows a typical example of the selectivity that can be obtained with the new ruthenium catalyst

produce good quality products for very long periods of time.

Comparison of Berty and Fixed Bed Reactor Results

The exothermic nature of the Fischer-Tropsch reaction means that careful account must be taken of heat transfer phenomena when scaling up to plant size e q u i p ment. An important part of the temperature control of a reactor is the linear velocity of the gas molecules through the catalyst bed, and this should be above a minimum value. The small fixed bed reactor used in this work had a typical linear gas velocity of 10 c d s which was well short of the minimum required. Consequently temperature control of the bed was poor and the use of the reactor was limited to durability studies. Furthermore the most active catalyst concepts could not be studied in this reactor due to thermal runaway. In comparison the

linear gas velocity of the Berty reactor was well above the minimum value and the catalyst bed could be considered to be isothermal.

Although the Schulz-Flory plots for the wax products (obtained from the Berty and fixed bed reactors) yidd reasonably straight lines, it was clear that both sets of data fitted curves. Conse- quently it was decided that rather than fit the data to a Schulz-Flory model, the a value would instead be calculated as a function of chain length. To achieve this the weight fraction versus molecular weight plot which was obtained from t h e Gel Permeat ion Chromatographic analysis of wax was converted to a number fraction versus carbon number plot. In order to calculate the a value as a function of carbon number it was necessary to calculate the number fraction at each carbon number. This was achieved by fitting a seventh order polynominal to the data using a matrix curve fitting program. The probability of chain

0.97967i Fixed bod roactor -_----- -. --- a

Y

2 3 0.96933

Fig. 7 During the course '0.95900 of the work described in L 50.94067 1 - ~ - - - - e - , - & y O ~ ~ t ~ . this article an interesting dependence of a, the chain 093833 growth probability factor, upon reactor type was observed

0.92800 15 30 45

CARBON NUMBER


growth a was then calculated according to the formula:

F ” + ,

F ” a = -

where F is the number fraction. The variation of a with carbon number obtained with both reactors is illustrated in Fig. 7. The fixed bed sample a was virtually constant and had a value of approximately 0.969. In contrast the Berty sample had an a value which increased from 0.943 to a steady value of 0.969 at a carbon number of approximately 40. The dependence of a upon a reactor type has previously been predicted in the literature (15). One conclusion that can be drawn from these cal- culations is that on using a similar catalyst a lixed bed reactor will tend to produce more and harder wax than that obtained with a Berty reactor under similar conditions.

The Future Prospects The worldwide introduction of the Fischer-

Tropsch process will primarily depend upon the availability of oil and on its cost. The use of ruthenium in the process will depend upon the availability of low ruthenium loading catalysts with good activity and selectivity compared with the presently used iron-based systems. We have successfully demonstrated that a low metal loading catalyst can be very active and also have good selectivity. In addition the catalyst was durable enough to survive on an extended laboratory durability trial with

little loss of performance. It is our belief that the use of new ruthenium catalyst systems as indicated in this article represents a substantial improvement on previously available ruthenium catalysts, and will achieve significant utilisation in commercial operations to produce premium products such as jet and diesel fuel and wax.

I

,

3

4

5 6

7 x

Y

10

I I

I ’

13

14 1 5

References

1’. Sabatier and J. B. Senderens, C. R. Acad. Sci., Paris, I 902, 134, 5 I4 I;. Fischer and H. Tropsch, Brennsr.-Chem.,

11. I’ichlrr, “Advances in Catalysis”. Academic I’rcss, New York, I 952, Vol. 4, p. 27 I

K. B. Anderson, “Catalysis”, Reinhold, New York, 1956, Vol. 4, p. 29; “The Fischer- Tropsch Synthesis”, Academic Press, New York, 1984 11. I’ichler, Breiiirsr.-Chem., 1938, 19, ( I Z ) , 226 I). I,. King,J. Caral., 1978, 51, 386 K . A. 1)alla Betta, 3. Caral., I 974,34, 57 1:. M. Dautzenberg, J. N. Helle, R. A. van Santen and H. \’erbeek, J. Catal. , I 977, 50, 8 M. A. Vannice, 3. Caral., 1975, 37, 449; 3. Curd., 1975,40, I29;J. Caral., 1976,44, 1 5 2

K . J. Madon, E. R. Bucker and W. F. Taylor, Final 1J.S. E K D A Report Contract No. E(46-1k8008, 1977 M. 1J. I k y , Iizd. Eiig. Chem., Prod. Res. Dev..

M. 1;. I k y , “Catalysis Science and Technology”, Springer Verlag, Berlin, I 98 I , p. I 59 K. C. i‘verson and D. T. Thompson, Plarinum Mrruls Rev., 198 I , 25, (z ) , 50 G. \’. Schulz, %. Phys. Chem. B. , 1935.30, 379 S. Novak, R. J. Madon and H. Suhl, 3. Calal.,

I923,4,276

197% 15, (41,282

1982,119 141

An Organometallic Chemistry Monograph Orpanometal l ic Chemistry of R h o d i u m a n d l r idi i im BY RONALD S. DICKSON, Academic Press, London, 1983~42 I pages, E6 I

’Ihe latest monograph in a series on organometallic chemistry deals with rhodium and iridium in a comprehensive yet very read- able way, and both the concepts and the structures are clarified with numerous illustra- tions. Following a general survey of the chemistry of rhodium and iridium, the author deals with specific topics: carbonyls in Chapter 11, their complexes in 111, pseudo carbonyls in I V (M-CS, M-PF3, M-CNR, M-NO and

M-N >K), organo-rhodium and -iridium complexes in V, alkyne complexes in VI and finally in Chapter VII a-alkyl, -aryl and related complexes.

The book is well supported by references to the literature which has been covered com- prehensively up to the end of 1978, with some key references from I 979 included. Additionally, an addendum to the key references from the recent literature is given.


The Corrosion Behaviour of Objects Electroplated with Platinurn IMPORTANT INFLUENCE OF INTERMEDIATE LAYERS

By M. Baumgartner and Ch. J. Raub Forschungsinstitut fur Edelmetalle und Metalkhemie, SchwSbisrh Gmund, West Germany

If base metals are thinly coated with platinum from an aqueous electrolyte the deposit is likely to be porous, thus enhancing the susceptibility 0.f the substrate metal to corrosion and the surface to discolouration in certain environments. This paper considers the processes involved and shows that the application of a suitable intermediate layer can effectively prevent this, so enabling the inherent properties of platinum to be utilised for a greater number of functional and decorative applications.

Thin layers of metallic platinum can be produced in a variety of ways: by electrolytic deposition from aqueous electrolytes or salt melts, by thermal evaporation or cathodic sputtering (the physical vapour deposition or PVD processes) or by firing printed pastes. Depending on the deposition process and the parameters involved, the properties of the coating can vary considerably. Those deposited from aqueous electrolytes at thicknesses of a few microns or less are highly stressed and porous, although bright, hard and wear resistant. Deposits from molten salts are generally more. than xpm thick; they are low stressed and have low porosity, being semi- bright in appearance, soft and highly ductile. Layers produced by the PVD processes are generally in the thickness range of o . ~ p m or less, and therefore rather porous. Fired ceramic pastes often form thick layers with internal porosity. These processes may compete for technical applications, for example coatings produced from aqueous electrolytes or by the PVD processes are used for decorative and functional applications by the electronics industry, on razor blade edges and on spectacle frames. Deposits from salt melts are found in the electronic, chemical and glass industries; fired platinum-containing pastes form decorative and functional coatings in similar areas.

With the exception of coatings deposited from salt melts, platinum layers a few microns thick are generally quite porous, which makes them difficult to use for the protection of less noble substrate materials. Where porosity in the platinum coating exposes a base metal surface, and in the presence of an electrolyte, the electrochemical nobility of platinum makes these regions very susceptible to dissolution of the base metal, discolouration of the platinum surface by corrosion products and changes in the chemical or mechanical behaviour which may result in premature failure of the coated object.

During the course of a research programme undertaken at our institute on the properties of platinum and platinum alloy layers deposited from aqueous electrolytes we found that even a thin intermediate layer could have a profound influence on the corrosion behaviour of nickel or copper alloy substrates coated with thin porous platinum coatings.

Electrochemical Considerations If two metals of different electrochemical

potentials are in direct contact in an electrically conductive aqueous solution then “contact corrosion” may occur. In this case an intermediate potential forms with a value between those of the two individual metals. Thus the


more noble metal is cathodically and the less noble metal anodically polarised, with the result that the corrosion rate of the latter is increased while that of the nobler metal is decreased. Such combinations frequently occur, for example cracked or porous layers of platinum, rhodium, gold or silver may overlay brass, bronze, copper or nickel. In many instances also a bright sulphur-containing nickel deposit is applied as an intermediate coating beneath rhodium or gold layers ( I ) .

As a first approximation, the “normal potential” of metals and alloys can be used to predict the corrosion behaviour of certain metal combinations (2 ) . However caution is essential as many factors not taken into account when establishing these “normal potentials” have a significant effect on corrosion taking place under practical conditions; such factors include for example solution composition (3). Table I shows the potentials of selected metals in a sodium chloride-containing solution and in artificial perspiration, as measured on suitably prepared samples with a Knick millivoltmeter.

In order for contact corrosion to occur, a potential difference must exist between the two metals and they must be in electrical contact. It is also necessary to consider their interaction

Platinum 400 Gold I 240 Palladium 190 Miralloyldl 140 Silver 140 Nickel 99.6 50 Bright nickel 40 Copper 10

Table I

Potential of Various Metals as Observed in Sodium (:hloride Solution and

Artificial Perspiration

420 2 50 230 150 220

65 45 15

I Potential la1

la1 As measured against a silverlsilver chloride electrode lbl According to DIN 50905. pH 7.5. 20aC IcI According to DIN 642411 Id1 50 copper-50 tin

Fig. 1 The principle of a contact corrosion localised couple is shown, as i t occurs when a crack through the platinum plating brings electrolyte into contact with the platinum and the copper substrate

with water and its constituents, that is with the H+ ions, the OH- hydroxyl ions and the dissolved oxygen. The principles of contact corrosion as it may occur at a crack in a platinum layer on a copper substrate are shown in Figure I .

The dissolution of the anode is determined by Faraday’s law, and from it the weight loss, AG, can be established:

where G = weight loss (grams), t = time (seconds), F = Faraday constant (96,500 coulombs), M = atomic weight, n = valence of the ions formed, and I = galvanic current (amperes). The current I depends on the diffcrence between the cathodic and anodic areas, and obeys Ohm’s law, the electrical resistance being made up of the resistance between the corrosion partners (internal resistance) and that within the electrolyte (external resistance). Reaction schemes I , 2, 5 and 6 apply. If the anode is insoluble Reactions 3 and 4 take place. The cathodic reactions may


Anodic and Cathodic Reaction Schemes 1 Anodic

I M e j M e X + + xe-

z M e X + + e

Cathodic

5 M e X + + xe- j M e

6 M e ( X + ' ) + + e- -) M e X +

7 H 3 0 + + e - + H20+fHz

8 + O 2 + H 2 0 + 2 e - j z(0H)

be just the anodic reactions reversed. If no metal ions are present-especially in acid solutions-protons or Ht ions may be discharged, if hydrogen overvoltage permits.

In the considered copper/platinum system, copper is dissolved anodically below defects in the platinum layer. At the cathodic platinum coating, either H+ ions are discharged as hydrogen or dissolved oxygen is reduced to OH- ions, depending on the conditions in the electrolyte (Reactions 7 and 8 apply). The dissolved copper ions migrate over the platinum surface discolouring it around the defects.

Test Procedures Using copper substrates the corrosion protec-

tion provided by platinum layers deposited from a commercial electrolyte onto the intermediate layers listed in Table I1 was studied. The test procedures used were immersion in artificial perspiration (ISO/DIS 6424/I), the

salts spray test DIN 50021 and the sulphur dioxide-containing Kesternich test (DIN 50018). All tests were terminated after 48 hours. During the Kesternich test the samples were examined after I , z and 5 cycles. The criterion considered was the visual appearance of a typical part of the surface after testing compared with that of an as-prepared sample; exceptional areas such as those showing edge corrosion were disregarded. The samples measured zcm x z.gcm and the thickness of the intermediate layers varied between I and IZ pm. The thickness of the platinum coating, which was deposited from a sulphuric acid- based commercial bath (Platinbad K, DEGUSSA

AG), was determined by X-ray fluorescence.

Corrosion in Perspiration A summary of the corrosion behaviour

observed in artificial perspiration is shown in Figure 2. All copper samples p!ated directly

Fig. 2 The summary of corrosion data, obtained after 48 hours in artificial perspiration ( I S 0 DIS 6424/I) shows the benefit of imposing a thin layer of gold, silver or copper-tin between the platinum coating and the copper substrate

I- z W V

.cI

% t t

--

Platinum Metals Rev., 1985, 29, (4) 157

Substrate

Copper Copper Copper Copper Copper Copper Copper Copper Copper

Intermediate layer* Outer plating

None Bright nickel Semi-bright nickel Silver Gold Palladium Palladium on gold 50 copper-50 tin Gold on silver

Platinum Platinum Platinum Platinum Platinum Platinum Platinum Platinum Platinum

In the electroplated form

with platinum showed very poor corrosion resistance, with corrosion covering the whole area. Sometimes the coating became separated from the base. The thickness of the platinum layer had no significant influence on this behaviour, since the attack was identical for 0.5 and I .opm thick layers. Microscopic investigations showed that it was not possible to produce crack-free deposits at these thicknesses from this electrolyte, see Figure 3. Attempts were therefore made to identify suitable materials for intermediate layers which would prevent cracks and/or porosity penetrating from the platinum surface through to the copper substrate, thus avoiding contact corrosion.

Bright, o r semi-bright intermediate nickel layers proved to have no positive effect. Bright nickel coatings between 5 and Iopm were studied. The attack resembled that observed on samples where platinum had been deposited directly onto copper, Figure 4. Bright nickel layers, especially very bright ones with high sulphur contents, are much less noble than semi-bright coatings with considerably less sulphur. The electrochemical potential of semi- bright nickel is closer to that of platinum than is the potential of very bright nickel. It was therefore interesting to see if the use of the former would reduce corrosion. However the corrosion resistance of samples with a 5 to 12pm thick intermediate layer was no better thdn that of samples with a very bright nickel layer, as can be seen in Figure 5 .

Fig. 3 The platinum layer 1 micron thick produced from the specified sulphuric acid based commercial electrolyte on a copper sub-

x 200 strate was severely cracked

Fig. 4 A crack through the 0.2 micron platinum coating has resulted in localised corrosion of the bright nickel intermediate layer (2pm) and the copper substrate x 1000

Fig. 5 Defects penetrate the 0.5 micron platinum coating enabling corrosion of the 12 micron thick semi-bright nickel intermediate layer to commence x 500


Table II

Layer Combinations

Fig. 6 Despite an artificial crack in the platinum layer (arrowed) the presence of the gold intermediate layer (3pm) prevents the occurrence of contact corrosion x 1750

If the copper substrate is plated with silver before the platinum coating is applied a pronounced improvement in the corrosion resistance is observed. Depending on the quality of the substrate surface, for example freedom from defects and low roughness, a 0.5 to r.opm thickness of silver is sufficient to completely

prevent corrosion, in the conditions employed. There are two possible explanations for this: [i] If there is no connection between the copper substrate and the platinum, through cracks or pores in the silver, then there can only be contact between silver and platinum. However, the contact potential between these two metals is too small (about 200mV) to cause appreciable damage. [ii] Silver chloride formed during any initial corrosion may block cracks or pores thus preventing any further corrosion.

An intermediate layer of gold with electrochemical potential of 25omV in artificial perspiration gives superb corrosion protection if it is fairly free of pores; a section through such a coating is shown as Figure 6. The porosity of plated layers depends on features such as the quality of the substrate and the electrolyte used, and in the conditions employed here a practically pore free coating was obtained at thicknesses in the range 2 to y m . Indeed some samples were free of corrosion when the intermediate gold layer was only one r p n thick.

Despite the fact that palladium has a slightly

I'ig.7 The corrosion behaviour of platinum plated copper substrates showing the marked c*Ft'c.c.i of the composition of the intermediate layer. Top row, left to right: copper/platinum (0.5~111). copper/semi-bright nickel ( 12pm)/platinum (0.Spm), copper/silver ( I,um)/platinum (0.5p11): bottom row, left to right: copper/gold (3pm)/platinum ( O S p m ) , copper/palladium (2pm)/ platinum (0.5pm). copper/copper-tin ( lpm)/platinum (0 .5pm)

Platinum Metals Rew., 1985,29, (4) 159

e a e - \

Fig. 8 Corrosion data for ? f various metal combinations

after 48 hours salt spray test (SS DIN 5002 1 ) show marked similarity with the

piration tests

- c

c results of the artificial pers-

higher potential than silver a rather strong contact corrosion is observed when a palladium intermediate layer is tested. Apparently a zpm thick palladium layer was too porous to prevent contact corrosion effectively. Furthermore the possibility has to be considered that a localised contact couple may have been formed between the palladium intermediate layer and the copper substrate. A gold strike o.r,um thick between the copper and the palladium had little influence on the corrosion behaviour, as compared with a gold-free sandwich structure.

If a “white bronze” or “speculum” type of electroplated deposit, such as Miralloy is used

for the intermediate layer, excellent corrosion resistance can be achieved, Figure 7. A layer about Ipm thick is sufficient to give a behaviour comparable with that of a gold or silver intermediate coating, even if the copper-tin deposit is less ductile. However, if cracks penetrate from the platinum outer surface through to the copper strong corrosive attack is observed.

Corrosion in Artificial Salt Spray Even when exposure in artificial perspiration

enabled us to make detailed statements on the behaviour of the various systems, the standardised salt-spray test (DIN 5002 I , 48

Fig. 9 The behaviour of plated samples in sulphur dioxide-containing a t - mospheres ( Kesternich test: DIN 50018 - SFW 2.0s) after 5 cycles showed some similarities with pre- vious tests, although a silver intermediate layer was not as effective unless overlaid with a gold strike

Plarinum MeraIs Rev., 1985,29, (4) 160

Fig. 10 The appearance of various platinum plated samples after f i v e rycles o f t h e Kes1c.rnivh test, showing that the use of a n appropriate intermediate layer, or layers t-nablvs ;I v w ! satisfactory corrosion-resistant finish to be produced o n a copper substrate

hours) was also applied. The results were quite similar, as can be seen by comparing Figures 2

and 8. No corrosion was observed for the coni- binations using gold, silver or copper-tin intermediate coatings. However, with nickel layers a much stronger attack sometimes occurred, as in artificial perspiration, possibly due to the loss of passivity of the nickel in solutions with a high chlorine concentration.

Sulphur Dioxide Test Results In order to observe the behaviour of the

plated objects during attack by gaseous corrosives we studied their reaction in the Kesternich test (DIN 5001 8). For combinations without intermediate coatings, or using nickel as an intermediate, the attack resembled that observed in the salt-spray test. A 2pm thick palladium intermediate layer showed no improvement either.

Of the precious metal intermediate layer? used a 2pm or more thick gold coating proved very effective in obtaining good corrosion resistance, as can be seen in Figures 9 and 10. Silver layers were not as effective here as in the

other tests, which can be explained by the attack of sulphur dioxide on silver and by the formation of fairly soluble silver corrosion products, compared with the rather insoluble silver chloride present in the other tests. However if the silver intermediate layer is given a gold strike below the final platinum deposit, and o.2pm is an effective thickness, the composite is resistant to the sulphur dioxide atmosphere, see Figure 10. The “speculum” copper-tin alloy again proved to be very effective for corrosion protection in this test, and it appears that it might be a suitable alternative to precious metals for the intermediate layer.

Summary The inherent properties of platinum make its

use as thin electroplated layers interesting for a variety of applications. However as a result of its high chemical nobility there is a danger that localised couples may form between the substrate material and the platinum near any defects in the platinum coating, thus causing high corrosion at these spots. In standard corrc- sion tests made on samples plated from a


specified sulphuric acid based commercial electrolyte intermediate layers of nickel proved to be ineffective for corrosion protection, as did palladium. In chloride-containing solutions silver proved to be very effective, not only due to its rather high nobility but also because of the formation of insoluble silver chloride corrosion products. Very good corrosion resistance under the test conditions was shown by the layered combination: platinum (outer)/Miralloy copper-so tin (intermediateycopper substrate, making this a very satisfactory alternative to totally precious metal systems.

Acknowledgements We wish to thank Impala Platinum Ltd. for

supporting our work on the electroplating of platinum and DEGUSSA A.G. for providing us with electrolytes and chemicals. Platinbad K and Miralloy are registered tradenames of DEGUSSA products.

References I K. E. Becker, H. Schlegel and A. Kubat,

2 G. Kortum, “Lehrbuch der Electrochemie”,

3 J. Elze and G. Oelsner, Metallob@he, 1958, 12,

4 E.Raub and W.Pfaer,Gold BulI.,1980,13,(3),1 I Z

MetallobJache, 1968, Z Z , (5 ) , 145

Verlag Chemie, Weinheim, 1958

(9, 132

Symposium on Fine Chemical Manufacture Platinum metal catalysts have an increasingly

important role to play in producing materials for the healthcare, plant protection and electronics markets. This is a conclusion drawn from the recent symposium entitled “Catalysis in Fine Chemical Manufacture” organised by the Royal Society of Chemistry from 1 ~ 1 2 t h July, at the University of Birmingham. Of the fourteen papers given, which covered a broad spectrum of catalytic subjects, eight contained references to platinum catalysed reactions, and three drew extensively on platinum metal catalysis to illustrate the importance of matching structure and function in catalysis. These are reviewed here.

Professor P. B. Wells of the University of Hull considered the objectives of catalyst design to be the preparation of catalytically active material in which the chemical and physical properties of the active sites are not degraded during use, and the minimisation of side reactions so that the catalysed reaction results in marketable products. These can be achieved through modification of the active site environment, by surface treatment to give car- bonaceous or sulphur deposits, by occlusion of hydrogen during reaction, or by the deliberate choice of a metal-support combination which interacts beneficially under the reaction conditions. With the platinum and titania combination, reduction of the TiO, to Ti,O, occurs locally, facilitating the passage of electrons from the metal to the support. With certain supported osmium clusters activity is dependent on the extent of electron transfer. Sintering is linked to metal-support interactions, and the anchoring of small platinum crystallites on silica by Pt-O-Si bonds helps to retard sintering.

Selectivity has been improved by the use of multifunctional systems, for example bifunctional platinum reforming catalysts and polyfunctional zeolite-based catalysts.

In his lecture “Composition and Structure of Catalysts for Vapour Phase Reactions”, Professor G. C. Bond of Brunel University described fixed and fluidised bed catalysts. Fixed bed reactors utilise large particles such as pellets, while fluidised bed reactors employ small particles of uniform size. Otherwise the catalysts are very similar, being composed of an active phase (a platinum metal), a support (such as alumina or silica), and a promoter which may alter the texture, electronic structure or poison resistance of the combination - as with the addition of rhenium to a platinum reforming catalyst. In phenol hydrogenations the catalyst is bifunctional, the platinum metal reducing the aromatic ring and the support acid function rearranging the intermediate to give a cyclic ketone. Metal location is important as it affects the mass transport within the pores. This factor is to a large extent determined by the method of preparation; fast absorption from solution gives uniform deposition within the pores while slow absorption allows metal to deposit at pore mouths.

Metal dispersion and location and the effect of these parameters on the activity-selectivity of reactions was the main theme of Mr I. L. Dodgson’s lecture. He described the types of palladium on charcoal catalysts manufactured by Johnson Matthey Chemicals for liquid phase reactions, discussed how their physical structure controls their behaviour in selected industrial reactions and recommended appropriate catalysts. A.J.B.


Automobile Exhaust Emissions Control LEGISLATION TO PROTECT THE EUROPEAN ENVIRONMENT

By R. A. Searles .lohnson Vatthey Chemicals Limited

Catalyst technology based upon platinum metals supported on a ceramic or metal substrate has been tried, tested and approved in the United States of America and in Japan for the control of carbon monoxide, unburnt hydrocarbon3 and oxides of nitrogen from vehicles. Australia is shortly to require a reduction in noxious emissions from this source, while in Europe a growing awareness of the detrimental effects of pollutants upon the environment has now led to a decision to introduce emission control standards. Over the past decade the motor industry has been supplied by Johnson Matthey with many millions of autocatalysts; now their accumulated expertise and manufacturing capacity will be available to meet the European demand, whether it be for udvanccd three-way catalysts, using platinum and rhodium, or for platinum + palladium oxidation catalysts to support anticipated dcvclopments in lean-burn engine technology.

On the 29th June 1985 European Environ- ment Ministers meeting in Luxembourg agreed on exhaust emission standards for motor vehicles that, when enacted, will define a market in Europe for emission control systems. This agreement ended a prolonged discussion on the levels at which future standards for Europe should be set. The new emission standards will be brought in over a five-year period commencing on the 1st October 1988. From that date new models of cars with engine capacities greater than 2 litres will have to meet the agreed standards in all European Economic Community (E.E.C.) countries that adopt the new directive. While a particular control system has not been specified, these cars are likely to use the rhodium+platinum three-way catalyst technology that is already widely used in the United States of America and in Japan to control carbon monoxide, hydrocarbon and nitrogen oxide emissions ( I ) . For cars with smaller engines less severe standards have been set, and it will be possible to meet these using alternative technologies. In particular it is

expected that lean-burn engines producing sig- niticantly lower amounts of nitrogen oxides will be developed, but in all probability these will have to be fitted with an oxidation catalyst to control carbon monoxide and especially the levels of hydrocarbon emissions associated with lean-burn engines. These catalysts are likely to be based on platinum and palladium, and the use of either catalyst is made possible by the fact that unleaded petrol must be introduced throughout the E.E.C. for all new model cars to use by 1st October 1989, at the very latest. Indeed a number of European countries are already encouraging the earlier introduction of unleaded petrol.

West German Initiatives Consideration of exhaust emission standards

for motor cars that could use platinum metal catalysts for their control started in Europe as long ago as July I 976. The Federal Republic of Germany's Environmental Agency, the Umweltbundesamt (U.B.A.), published a paper that proposed the application from 1980 of


Fig. 1 Close collaboration between motor manufacturers and catalyst suppliers ensures optimised use of catalyst technology. Here a Ford Sierra is undergoing test on a rolling road dynamometer at the Emission Test Laboratory of Johnson Matthey Chemicals Limited where carbon monoxide, hydrocarbon and nitrogen oxide emissions can be continuously measured as a vehicle is put through a specified driving schedule. Catalyst durability and performance may also be assessed by running a test vehicle on a road circuit

tighter exhaust emission standards. These standards would meet the goals set by the Federal Republic’s Government in 197 I , which sought a 90 per cent reduction in the pollutants emitted by motor vehicles from 1969 levels. The U.B.A. generated the data necessary to set the proposed standards and conducted a technical evaluation of methods available to meet them. One of the methods proposed was the use of lead-tolerant catalysts, because at that time it was considered unlikely that unleaded petrol would be available on a widespread scale in Europe. These proposals initiated programmes of work by the catalyst industry which have been reported previously (2).

Pressures for Unleaded Petrol In Europe, at present it is still standard

practice to add lead to petrol to improve the octane rating and its presence would cause the rapid poisoning of any catalyst. Thus consideration of the platinum metal catalyst technology

developed for markets in the U.S.A. and Japan was not seriously possible in Europe until April 1983 when a Royal Commission report entitled “Lead in the Environment” was published in the United Kingdom (3 ) .

This included among its recommendations that the Government should begin urgent discussions with the U.K. oil and motor indusiries in order to agree a timetable for the introduction of unleaded petrol. In announcing the report to the U.K. Parliament, the Secretary of State for the Environment said that the Government accepted in full the findings of the Royal Commission and that it would seek, on health grounds, in consultation with its European partners, to reach agreement on a date for a pan-European introduction of unleaded petrol. The target date for reaching that agreement was 1989.

During the same period there was considerable political activity in the Federal Republic of Germany. The ecological Green Party was


Agreed European Automobile Emission Control Standards

New models

October 1988 October 1991


Engine capacity

All new cars



Over 2 litres 1.4-2 litres Less than 1.4 litres: First stage Second stage

Date of introduction

already gaining major support and there was public concern at reports that acid rain was destroying German forests. The motor car was cited as a major contributor to acid rain and on 20th July 1983 the Cabinet of the Federal Republic of Germany announced legislation that would require all new cars registered in Germany from 1st January 1986 to be engineered to operate on unleaded petrol and to be fitted with catalysts. After much subsequent discussion this was confirmed in a decision of 26th October 1983 which stated that unleaded petrol and an approximately 90 per cent reduction in car exhaust emissions using “best current technology” were to be enforced from 1st January I 986. This Cabinet decision stated that current U.S. Federal standards and test procedures were to be used, which effectively specified the use of rhodium+platinum three- way catalysts. This set the scene for further discussions in Europe.

The European Debate The major arenas for debate and negotiation

on emission standards have been the European Commission in Brussels and meetings of the Council of Ministers of the E.E.C. who come together twice yearly immediately prior to the biannual summit of European Heads of Government. At these meetings there has been a wide diversity of opinion on the need for tighter emission standards in Europe, ranging from those countries who proposed a marginal

Emissions, gramdECE Test

Carbon monoxide

25 30

Hydrocarbons and nitrogen

oxides

6.5 8

Nitrogen oxides

3.5 -

45 I 15 1 6 To be decided by 1987

tightening of current emission standards through to Germany demanding full U.S. standards. Following meetings in December 1984 and March 1985 a compromise agreement was reached which attempted to balance the commitment of the Federal Republic of Germany and its supporters to U.S. standards against the view of the U.K. Government who, although it was at the forefront of the move to unleaded petrol, has been opposed to insistence on three-way catalysts as implied by the German proposals. ’The U.K. Government was concerned that such regulations would stifle the development of lean-burn engines which it believes will offer fuel economy advantages.

A Framework for Agreement The I 985 March agreement set the principles

of a political framework for a European standard based on the current European emissions test procedures, but which would have an effect on the European environment equivalent to that produced by U.S. standards.

For cars over 2 litres it was anticipated that this would mean the use of three-way catalysts, while for medium sized cars from 1.4 to 2.0 litres engine capacity the European standards would also encompass the use of lean-burn engines coupled with oxidation catalysts. For small cars, below I .4 litres, tighter emission standards are to come in two stages, the first stage requiring only engine modifications while the standards for the second stage are to be agreed by 1987. A


(latest dates)

Fig. 2 Since 1974 Johnson Matthey has been supplying the motor industry with emission control catalysts for cars sold in the U.S.A., Japan, Australia and, increasingly, for German. Austrian and Swiss markets, from manufacturing facilities in both England and the U.S.A. ‘The autocatalyst units shown here during processing at the Royston factory consist of rc-ramic honeycomb monoliths which form a lightweight, high surface area support upon which a high surface area washcoat is deposited prior to coating with the finely divided platinum metals that catalyse the destruction of the exhaust pollutants

June meeting was set to agree the levels of pollution that cars would be allowed to produce in order to meet the framework of agreement from the March meeting. This proved to be more difficult than at first thought and although the European Commission had earlier proposed a set of numbers, these were regarded as either being too severe or not severe enough.

The final agreement can be summarised by the data in the Table.

The agreement reached was, in the case of the United Kingdom, only for consideration and subject to a general reserve by Denmark who would not agree to any standards less severe than current U.S. standards, The United Kingdom in fact confirmed its agreement to the standards in early July.

For cars of 1.4 to 2.0 litres in capacity the standards have been carefully chosen to meet the original directive of the European Commis- sion which stated that they should be achiev-

able to the maximum extent possible at reasonable cost and by different technical means. In particular it should be possible to satisfy the standards by simple lean-burn techniques, combined with an oxidation catalyst.

Lean-Burn Engines Lean-burn engines have been under develop

ment since the 1970s. The diesel engine is a successful example of a true lean-burn engine. It was in recognition of the advantages of diesel engines in terms of fuel economy and lower levels of nitrogen oxide pollution that emissions engineers in the motor industry sought to produce petrol engines that would operate with air:fuel ratios as lean as those possible in ti

diesel engine. At air:fuel ratios greater than 20:1 the production of nitrogen oxides is considerably reduced and better fuel economy is obtained. However, emissions of hydrocarbons increase. There is, however, sufficient excess


oxygen in the exhaust gas to enable those hydrocarbons to be removed simply by fitting an oxidation catalyst into the exhaust system.

The challenge for the engineer is to maintain combustion and driveability at these lean air: fuel ratios. This is achieved by encouraging tur- bulence in the engine’s cylinders and by the propagation of a large flame area at early stages of the combustion process. Heat losses from the engine are minimised by designing the combustion chamber with a minimum surface area: volume ratio. Also, to ensure good combustion it is necessary to produce a high energy spark.

Conclusions The motor industry now has two alternative

technologies to meet the new standards. Already in the Federal Republic of Germany, where there are fiscal incentives to encourage the sale of “clean” cars by collecting lower road tax, three-way catalyst cars are being sold and

Space Station Auxiliary Resistojets have characteristics that make

them attractive for space station auxiliary propulsion systems. For this arduous application the resistojet must have the capability of functioning with a variety of onboard propellants such as carbon dioxide, methane, hydrogen, ammonia and hydrazine.

Because of its excellent resistance to corrosion and high temperature oxidation, platinum has previously been considered for a similar application, but pure platinum was found to have inadequate strength. Many rhodium- platinum alloys are stronger, but in carbon dioxide at temperatures above 12oo0C a volatile rhodium carbonyl compound forms and this loss of rhodium weakens the alloy. After extended operation at high temperatures platinum and its alloys also experience grain growth, which results in reduced stress-rupture performance, the formation of voids and physical distortion. It was for these reasons that grain stabilised platinum metals were developed in the late I 960s and early I 9709, primarily for use in the glass industry.

The preliminary results of compatibility experiments made to determine the effects of different propellants on platinum stabilised with 0.6 per cent yttria have recently been

unleaded petrol is widely available. Undoubtedly some car manufacturers will opt for this proven route, and particularly for cars greater than z litres the three-way catalyst using platinum promoted by rhodium will be the preferred choice. For smaller cars, the choice is between the lean-burn engine, fitted with a palladium-promoted platinum oxidation catalyst and the three-way catalyst with an engine fuel management system controlled to ensure that the exhaust maintains the stoichiometry necessary for efficient operation of the three-way catalyst.

References I B. Harrison, B. J. Cooper and A. J. J. Wilkins,

Platinum Metals Rev., 1981, ZS,(I) , 14 2 A. F. Diwell and B. Harrison, Platinurn Metals

Rm.9 19819 25, (41, 142

3 “Royal Commission on Environmental Pollution”,

4 Press Release 7803/85, European Commission, 9th Report, April 1983, H.M.S.O.

27/28 June 1985

Propulsion Jets reported by M. V. Whalen, S. P. Grisnik and J. S. Sovey of the National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio, U.S.A. (“Compatibility Experiments of Facilities, Materials, and Propellants for Electrochemical Thrusters”, NASA Tech. Memo. 86956,1985,16 pp).

For the tests, which generally lasted for IOO hours, annealed tubes of grain stabilised platinum were formed into coils. When surrounded by a flow of carbon dioxide, hydrogen or ammonia, an electric current was passed through the coils heating them to 13oo~C, a typical operating temperature for resistojet heaters. Coils were also tested in a flow of methane and in mixtures of carbon dioxide and methane while heated at 500 to 6oo0C, a range chosen to avoid carbon deposition.

Measurement of mass losses after testing indicated a minimum life of IOO,OOO hours, which exceeded by a factor of ten the life required for the potential space application. Some corrosion of the surface occurred during heating in hydrogen and more especially in the ammonia environment. While grain stability was apparently not affected during these short- term tests, the results of long-term exposure to reducing atmospheres has yet to be determined.


A Standard Platinurn/Silica Catalyst A SUMMARY O F T H E FIRST REPORT OF T H E HESEARCH GROUP ON CATALYSIS O F T H E COUNCIL O F EUHOPE

By Professor P. R . Wells Chemistry Department, University of Hull. England

The platinum on silica catalyst designated EUROPT-I has recently become available as a standard reference catalyst for [he scientijic communities in academy and industry. The material, which was manufactured by Johnson Matthey, has been characterised by the Council of

Europe’s Research Group on Catalysis, and the full report of that characterisation study is about to appear in

The Research Group on Catalysis of the Council of Europe was formed in 1975 following an initiative by Professor Eric G. Derouane of the University of Namur. The Group is one of several which functions under the aegis of the Council’s Committee on Science and Technology. It consists of twenty-four persons with active research interests in heterogeneous catalysis by metals, drawn from laboratories in nineteen universities and research institutes situated in eight European countries.

Early in its life, the Group selected catalyst characterisation as one of its main areas of collaborative work, and its first report, the characterisation of a platinudsilica catalyst code-named EUROIT-1, will shortly appear as five papers in the journal Applied Catalysis. The present author was privileged to act as co- ordinator for the scientific programme and as the main author of the Report. This article summarises the main features.

The Project Philosophy EUROPT-1 was prepared by Johnson

Matthey Chemicals under the supervision of Dr. Dennis E. Webster. The order was for 6 kg of catalyst; of this one half was retained as stock for future division into small samples for the benefit of the scientific communities at large, and the remainder was distributed in zoog samples to members for charact&isation.

At an early stage the Group had to decide

the scientifie literature.

whether they should specify apparatus designs, and experimental procedures and conditions, or whether they should encourage the use of existing apparatus and routines. The latter was deemed acceptable, and each Group member was asked to carry out those measurements for which their laboratory was best equipped. This decision led to a remarkably successful study ranging over the areas of chemical composition, total surface area, the size distribution of the platinum particles, and chemisorption properties.

The specification drawn up by the Group requested the preparation of a reduced silica- supported platinum containing a metal loading of about 6 per cent. This, we appreciated, was an unusually high loading for platinum, but our central intention was to have a catalyst which contained platinum particles of such a size that the majority would be clearly visible by high resolution transmission electron microscopy. This approach has enabled an estimate of metal dispersion to be made by electron microscopy, and this has provided an invaluable reference point against which to interpret the chemisorp tion properties.

The Catalyst EUROPT- 1 The catalyst was prepared by an ion-

exchange method; 6 kg of silica (Sorbosil AQ U30 from Crossfield Chemicals) was stirred with 60 litres of o . o ~ M l’t(NH3)Kl~ solution,


60

30

60

30

+ z W U I W

40 I W

2 0

0

2 0

0

20

0

a b

1 2 i

9

d i

e

DL I 2 3

f

dL 1 2 3

I h I

n I

j

1 2 3 4 I 5 6 7 8 9 1 0 1 1 12

PARTICLE S I Z E IN nrn

Fig. I Size distributions of the platinum-containing particles determined by high resolution transmission electron microscopy. Histograms refer to the following samples: a to e as-received EUROPT-1 as measured in five laboratories; C E:IJHOI’T-I re-redueed in hydrogen at 623 K for 2 hours (zero sintering condition); g to j sintering observed when EUROPT- 1 was re-reduced in hydrogen at, respectively, 873 K for 5 hours, 1073 K for 6 hours, 1273 K for 4 hours, and 1273 K for 15 hours as measured in four laboratories


the slurry being kept at pH 8.9 by addition of a basic reagent consisting of o . o ~ M Pt(NH 3)4C12 and O.IM Pt(NH3),(OH),. The material was then filtered, washed, dried, and reduced in hydrogen at 673 K.

Total surface area of as-received EUROPT-1 is 185 5m2/g and the metal loading is 6.3 weight per cent. It is well suited for characterisation studies; it is granular and can be easily handled, its weight loss on drying is minimal (0.1 per cent at 473 K), it is suitable for examination by electron microscopy, and so far it has shown no changes with age.

The as-received material has a grain-size distribution and, because the platinum is distributed over the surface of the grains, the larger grains contain a somewhat lower loading of platinum per unit weight. For example, grains of about 500 pm in diameter contain about 5.7 weight per cent platinum.

Trace element analysis showed the presence of aluminium and calcium, each 500 ppm; sodium and titanium, each 400 ppm; magnesium, 200 ppm; potassium, 150 ppm; iron, 90 ppm; chlorine, less than 50 ppm; and chromium, about 10 ppm.

X-ray photoelectron spectroscopy showed the presence of carbon and nitrogen, in addition to the expected platinum, silicon and oxygen. The line-shapes for peaks assigned to platinum suggested incomplete reduction of the metal, and this was clearly demonstrated by applica-

z w 0

a n > I

tion of extended X-ray absorption fine structure (EXAFS) spectroscopy (6) which showed that the majority of platinum atoms in as-received EUROPT-1 have oxygen atoms as nearest neighbours, and not platinum atoms as expected.

Clearly, atmospheric oxidation of the initially reduced platinum occurred after the manufacturer’s preparation. However, this was not an impediment to the study, because re- reduction of EUROPT-1 at temperatures below that used in manufacture (673 K) results in no change of the platinum particle size distribution.

1 0 0 200 300 -0-3-

The Platinum Particle Size Distribution

Electron micrographs were obtained in seven laboratories with as many electron microscopes. All reported that the silica support was ade- quately translucent and that the platinum- containing particles were easily visible. The appearance of the micrographs was entirely normal for a material of this type; some of the particle size distributions for as-received EUROPT-1 are shown in Figure I (parts a to e). These histograms differ slightly in appearance because the bands within which particle size was measured differed from one laboratory to another. However, all laboratories report the presence of platinum particles in the range 0.9 to 3.6 nm, there being a maximum in the

5 - 1 I 2 0 c

Fig. 2 Isotherms for the adsorption of hydrogen on EUROPT-I at room temperature as measured in three ranges of pressure in four laboratories


distribution at or a little below 2.0 nm, and about 75 per cent of the particles are less than or equal to 2.0 nm in diameter. This agreement is very gratifying and leads to the conclusion that the platinum particles in EUROPT-1 re- reduced below 673 K have a dispersion close to 60 per cent.

As-received EUROPT-1 showed no ’change in the particle size distribution of the platinum- containing particles when samples were heated in air at temperatures up to 800 K. Re- reduction in hydrogen at temperatures below 673 K resulted in no sintering (Figure 10, but progressive sintering occurred at 873 K, 1073 K, and 1273 K (Figure I , parts g to j). As yet, the details of the sintering process have not been investigated.

The Chemisorption of Hydrogen It is common practice to calculate a value for

the degree of dispersion of platinum in a catalyst by, first, measuring an isotherm for the adsorption of hydrogen on the catalyst at room temperature, second, attributing the “saturation region” to monolayer coverage, and third, assuming that the Hadrarbc~Ptsurface stoichiometry is I .o: I .o. Our study demonstrates how perilous a procedure that would be if applied uncritically

It is shown in Figure 2 that conventional- looking isotherms are obtained for hydrogen adsorption .on EUROPT-1 at room temperature, but that the uptake at the plateau region is pre-

to l‘.UROI”I‘-1.

ssure dependent. A more extensive study of desorption isotherms at various temperatures shows that, over a wide range of equilibrium pressures (six orders of magnitude at 290 K) the adsorption obeys the Temkin equation. Thus, the plateau regions in Figure 2 are generated by this method of plotting the results, and should not be interpreted as denoting surface saturation or monolayer capacity. Indeed, the condition for full surface coverage is not clearly recognisable from the isotherms, unless it is the value to which the dashed extrapolations of the isotherms at 193, 290, and 373 K converge (see Figure 3). That value is about 200 micromoles H, per gram, which exceeds one hydrogen atom per platinum atom present in the adsorbent.

Temperature programmed desorption revealed the presence of four states of adsorbed hydrogen which underwent desorption in the temperature range IOO to 900 K (Figure 4). State A hydrogen (T,,, - 200 K) was weakly, perhaps nondissociatively adsorbed; state B hydrogen (Tmm - 400 K) was attributed to hydrogen atoms adsorbed at surface platinum atoms; state C hydrogen (T,,, - 550 K) appeared to be the product of reversible processes associated with the supported metal interaction, see the Equation below; and state D hydrogen (T,,, - 750 K) was conventional spill-over

Si-0-Pt + H, + Si-OH + H-Pt

hydrogen which, in the desorption experiment,

Fig. 3 Isotherms for the desorption of hydrogen on .m2,,. K L K O P T - 1 a t t h r e e I

temperalures over a very 5 wide range o f equilibrium pressure as measured in u on(% laboratory E

d : 100-

> L . -4 -2 0 2 I 4

LOG,,(EOUILIBRIUM ,PRESSURE OF H2,torr)


I1 ) * \ r \ I ’ \‘ ’.

*.’ \ . , .: 9c 706 joo 500 700 100 300 500

T E M P E R A T U R E , K

Fig. 4 Profiles for temperature programmed desorption of hydrogen from EUROPT- 1 as measured in two laboratories. The four states, A, B, C and D are described in the text. Part (a ) shows three profiles, one for each of three extents of initial hydrogen coverage

spills back onto the metallic function and undergoes atom recombination to give gaseous dihydrogen molecules. The population of state B hydrogen was such that, if the Hsdoorkd: PtSufi,, stoichiometry is I .o: 1.0, then the dispersion of the platinum is about 65 per cent, in fair agreement with that obtained by electron microscopy.

Further work is necessary in order to determine whether re-reduction conditions can be found which provide hydrogen mostly in state B, with minimal contributions from states A, C and D.

The Chemisorption of Oxygen and of Carbon Monoxide

Oxygen chemisorption and carbon monoxide chemisorption onto reduced EUROPT-1 at room temperature each gave isotherms of the type shown in Figure 5 .

For oxygen chemisorption, extrapolation of the high pressure region of the isotherm to zero pressure gave values of about 86 micromol0 Jg. On the assumptions [i] that this approximates to surface saturation of the exposed platinum atoms by adsorbed oxygen-atoms, and [ii] that the platinum dispersion is 60 per cent, then the 0 adoorkd:Pt stoichiometry is 0.9: I .o at room

temperature. This is rather higher than the values obtained from chemisorption studies of oxygen atoms adsorbed on single crystal planes of platinum, and may indicate a special chemistry for oxygen at the surfaces of very small platinum particles. Alternatively, it may indicate that some bulk oxidation occurs. In our study, it was noticed that the extent of oxygen adsorption increased with increasing temperature, and that even at room temperature a slow oxygen uptake followed the fast uptake recorded in the isotherms. Moreover, as noted previously, the as-received EUROPT-1 was substantially oxidised, indicating a considerable sensitivity of the platinum crystallites towards oxygen. Thus, oxygen chemisorption at room temperature appears well-behaved as regards the form of the isotherm, and the number of oxygen atoms adsorbed at a pressure of a few torr appears to “count” the number of surface platinum atoms. There is, however, no firm scientific basis for the use of this measurement as a means of determining dispersion.

Carbon monoxide isotherms were measured at room temperature only. Extrapolations to zero pressure provided values for the uptake of 190 f 10 micromol CO/g which corresponds to


Fig. 5 Isotherms for the adsorption of oxygen on 4'' E t ' R o i ' ' r - 1 a t r o o m o temperature as measured in ; two ranges of pressure in three laboratories .-

g 80

E

W

6 1 0 0 2 00 300 -0-

i 2 i + EQUILIBRIUM PRESSURE OF O , , tarr

(1.14 & 0.06)10~~ CO moleculedg. Thus the ratio COadsork,$ttota, = 0.6:1.0; and if the dispersion of platinum is indeed 60 per cent as indicated by electron microscopy, then the adsorption stoichiometry ratio COndsorkd: Ptlurfscc must have been close to 1.0:t.o. Infrared spectra (Figure 6) of carbon monoxide supported on reduced EUROPT-1 showed the majority of the molecules to be in the linearly-adsorbed state (vco = 207 dcm) but small concentrations of the bridged-species (v cc = 1843/cm) and of a third species, possibly in a capped configuration ( V C O = 1708/cm), were also formed. The above-mentioned stoichiometries are, again, higher than those observed for

carbon monoxide adsorption on close-packed single crystal surfaces of platinum (for example Pt( I I I)), but they are not inconsistent with the values observed for [a] carbon monoxide adsorp tion on more open single crystal surfaces (for example Pt( I 10) for which CO ndsoorw:Pt =

I.O:I.O (7)) and [b] high nuclearity carbonyl clusters of platinum, for example Pt,,(CO); (8).

Main Findings of the Study The main observations and findings of this

characterisation study are set out below; a wealth of greater detail on these and other topics is contained in the original papers.

[ I ] EUROPT-1 is a 6.3 weight per cent

1 8 4 3

2071

Fig. 6 Infrared spectra of carbon monoxide adsorbed on ELItt0PT-I as measured for the Group by Professor N. Sheppard and co-

2000 1 8 0 0 1 6 0 0 workers at the University of C n F ' East Anglia


platinum on silica catalyst prepared by Johnson Matthey by an ion-exchange method.

[z] The total surface area is 185 ? sm2/g. The platinum particles, which are substantially oxidised in the as-received material, have a size distribution which ranges from 0.9 to 3.5 nm with a maximum at or a little below 2.0 nm in diameter. 75 per cent of the platinum containing particles are less than or equal to 2.0 nm in diameter.

[3] On re-reduction below 673 K the degree of dispersion of platinum in EUROPT-1 is judged by electron microscopy to be close to 60 per cent.

[4] Isotherms for the adsorption of hydrogen, carbon monoxide and oxygen can be measured with ease in conventional apparatus, and good agreement regarding the extents of adsorption under defined conditions of temperature and pressure have been obtained from a wide range of laboratories (for full details see original papers).

[ 5 ] Interpretation of the adsorption isotherms is not straightforward. The extents of adsorption at high coverage exceed “normal” expecta- tions. In the case of hydrogen adosorption, this is attributable to the formation of four adsorbed states only one of which (albeit the most highly populated state) is related directly to the degree of dispersion of the platinum. In the cases of carbon monoxide and oxygen adsorptions, the adsorprion stoichiometry at the surface of the small platinum particles appears to be such as to permit a higher extent of adsorption per unit area of surface than the Group originally expected.

lherefore, it appears safer at the present time to use values for the degree of dispersion obtained from electron microscopy to probe the stoichiometry of adsorption for very small metal particles, rather than to assume adsorption stoichiometry in order to determine the degree of dispersion.

In Conclusion EUROPT-1 has proved very acceptable as a

material for this catalyst characterisation exercise. It is the most highly characterised

catalyst currently available, and should prove to be of value in many industrial and academic laboratories as a standard against which to test experimental procedures.

Full information is contained in References I

to 5 , to be published shortly, and anyone wishing to obtain a sample should contact the chairman of the Group, Professor V. Ponec (see Appendix for address). Persons wishing to discuss results obtained using- EUROPT-1 are welcome to write to the author at the Depart- ment of Chemistry, University of Hull, Hull, HU6 7RX, England.

Ibferences G. C. Bond and P. B. Wells, (Characterisation of the Standard PlatinudSilica Catalyst EUROPT-I . Part I , “Philosophy and Achievement”), Appl. Caral., 1985, in press

G. C. Bond and 1’. B. Wells, (Part 2, “Preparation, Physical Properties, and Chemical Composition”), Appl. Catal., 1985, in press J . W. Geus and P. B. Wells, (Part 3, “The Size Distribution of the Platinum-Containing Particles”), Appl. Caral., I 985, in press A. Frennet and P. B. Wells, (Part 4, “Chemisorp- tion of Hydrogen”) Appl. Cafal., I 985, in press P. B. Wells, (Part 5 , “Chemisorption of Carbon Monoxide and of Oxygen”), Appl. Caral., 1985, in press R. W. Joyner, 3. Chem. SOC., Faraday Trans. I ,

‘1‘. E. Jackman, J. A. Davies, D. P. Jackson, W. N. Unertl and P. R. Norton, Surf. Sci., 1982,120,389 1’. Chini,J. Organomer. Chem., 1980, 200, 37

1980,16357

Appendix Current full members of the Council of Europe

Research Group on Catalysis are: Austria, H. L. Gruber, Innsbruck; Belgium, B. Delmon, Louvain- la-Neuve; E. G. Derouane, Namur; A. Frennet, Brussels; P. A. Jacobs, Leuven; France, J. Barbier, Poitiers; G. Leclercq, Lille; G. Maire, Strasbourg; R.Maure1, C. Naccache, J. C. Vedrine, Villeurbanne; Germany, G. Ertl, H. Knozinger, Munich; The Netherlands, J. W. E. Coenen, Niimegen;-J. W. Geus, Utrecht; J. H. C. van Hooff, R. Prins, Eindhoven; V. Ponec, Leiden; Spain, G. Munuera, Seville; Sweden, R. Larsson, Lund; P. Stenius, Stockholm; United Kingdom, G. C. Bond, Uxbridge; 1’. B. Wells, D. A. Whan, Hull.

Samples of EUROIT-1 can be obtained for research and calibration purposes: persons interested should contact the Group chairman, Professor Vladimir Ponec, Gorlaeus Laboratoria, Rijksuniversiteit te Leiden, Postbus 9502, 2300 RA LEIDEN, The Netherlands.


The Production of Palladium Powders for Electronic Applications REACTION CONDITIONS DETERMINE SURFACE CHARACTER

By G. G. Ferrier, A. R. Berzins and N. M. Davey Johnson Matthey Technology Centre

Recent investigations into metal powder fabrication by chemical precipitation techniques have shown that a wide variety of powder morphologies can be obtained by making subtle changes in the reaction parameters. Palladium powders produced using these techniques find wide application in the microelectronics industry, particularly as metallisations for multilayer ceramic capacitors or in thick film interconnection systems.

The microelectronics industry requires metal powders for incorporation into thick film inks or pastes, and the technology of thick film materials and their application to microelectronics has been extensively reviewed (1-6). The major uses of such inks occur during the manufacture of hybrid integrated circuits where they are screen-printed and then fired to form the conducting layers of the interconnection system or to form the internal electrodes of multilayer ceramic capacitors (MLCCs).

The properties of the metallic components of thick film inks intended for the internal electrodes of MLCCs are extremely important as compatibility is required between the metal powder and the organic medium of an ink, and between the ink itself and the surrounding dielectric material of the MLCC. The most widely used metals for this application are palladium or palladium-silver composites.

Historically, metal powders prepared by the chemical reduction of simple metal salts were used in the manufacture of MLCCs. However, such powders were often extremely fine with particle diameters of 0.001 to 0.1 pm, they exhibited a high surface area 0 1 o m ’/g) and as a result were often catalytically active or even pyrophoric. Consequently they were of only limited use when combined with an organic

medium to form screen printable thick film inks. They suffered from three very serious disadvantages, in particular: [i] High surface area powders require excess organic medium for adequate wetting of the powder during paste fabrication, and this can have a detrimental effect on the final rheology. The high oxide content associated with such powders can promote excessive gelling of the ink and screen printing may therefore become difficult. [ii] During the firing stages, the fine material can interact catalytically with the organic medium of the ink creating hot spots inside the assemblies and leading to rapid vapour release, blistering and delamination of the capacitors as they are formed. [iii] During the latter stages of firing, the metal powder sinters and shrinks. The shrinkage characteristics of very fine metal powders are usually excessive and unlikely to match that of the surrounding dielectric material. Conse- quently, tiny “islands” of metal are formed which result in discontinuous metal patterns of poor conductivity. Shrinkage incompatibility can also lead to delamination.

Thus it was considered necessary ‘to produce relatively non-active metal powders which would be fine enough to be used in thick film pastes but of sufficiently low surface area to

Platinum Metals Rev,, 1985,29, (4), 175-179 175

inhibit catalytic activity. On firing, such materials should also possess shrinkage com- patible with the surrounding dielectric in order to form smooth, high density metallisations. Therefore there was a requirement for a range of powder types of varying morphology, surface area and tap density, depending upon the organic medium chosen to make the ink and the dielectric selected for the MLCC.

Recent investigations at the Johnson Matthey ‘Technology Centre have been concerned with the fabrication of suitable metal powders for such applications. The method adopted was derived from electroless plating techniques, with metal salts and complexes in an aqueous medium being precipitated to the metal by the action of a chemical reducing agent.

Studies reported in the literature (7, 8, 9) have led to the general observation that precipitation is a combination of a number of stages, namely: nucleation, where solid phase particles are formed out of a liquid phase; growth, where solid material grows around the original nuclei; and agglomeration where the particles collide and combine. A supersaturated solution is, of course, one which contains more solute than that indicated by the equilibrium solubility or saturation point, and is a prerequisite for the growth mechanism to take place; while nucleation, which may be promoted by the presence of impurity substrates, requires even higher levels of saturation. However, when the precipitation of metals by the chemical reduction of metal ions from aqueous solution is under consideration, concepts such as saturation, supersaturation, nucleation and growth become less certain in view of the vanishingly small solubility of metals in water, and there appears to be very little published in the literature about this form of precipitation.

The investigations made at these laboratories have shown that although the basic reaction remained the same, which in the case of palladium is Pd I + + ze+Pd? subtle variations in the reaction parameters can have B remarkable effect on the physical characteristics of the

metal powder formed. For this purpose important variables include the concentration of the reactant or the reducing agent, the form of the metal salt or complex, the choice of the reducing agent, the reaction temperature, the mode and degree of agitation of the solution, the solution viscosity and the presence of additives or polyelectrolyte surfactants

Surface Morphology of the Powders The results of this work are illustrated by the

scanning electron micrographs which show a variety of palladium powders, all at similar magnifications. A very fine, high surface area (>rom’/g) material which, for the reasons out- lined earlier, is of little use in MLCC applications, is shown in Figure I . Figure 2 illustrates a nodular powder having a lower surface area ( I

to 2m yg); however, the surface irregularity and wide particle size distribution promotes uneven sintering during the firing stages and this leads to poorly defined conducting layers. Figure 3 shows a dendritic material which displays sur- prisingly good sintering characteristics which are considered to be due to the formation of a mat-type structure during printing. This same factor, however, can result in screen blockage which makes the powder of little direct use. A powder composed of spherical particles is shown in Figure 4; again the high level of agglomeration would result in poor as- fired properties. Figures 5 and 6 illustrate powders consisting of spherical particles but here there is less agglomeration. This is the type of powder most useful for MLCC fabrication, the smoother surfaced material possessing superior sintering properties.

Subtle alterations to precipitation parameters can also be used to control particle size and agglomeration, as shown in Figures 6, 7 and 8. Consequently surface area, tap density, Scott Density and Fischer Sub Sieve Size can also be regulated. The powder illustrated in Figure 8 has a particularly low particle size (~0.1 pm diameter) that facilitates printing of a buried electrode to a minimal thickness, but which retains a coherent structure. The use of this type of powder is expected to increase in the


Fig. I This very fine, high surface a rea type of powder, often referred to as a “black” because of its very dark appearance, is of little use in microelectronic applications

Fig. 2 Although having a lower surface area than the powder in Figure 1, this nodular powder has a wide particle size distribution and suffers from uneven sintering during firing leading to discontinuous metal layers

Fig. 3 Dendritic powders such as this form a mat structure on screen printing leading to strong, coherent fired layers. However, a t endency f o r s c reen blockage to occur during printing makes powders such as these of limited practical use

Fig. 4 This powder is composed of large, semi- nodular, uneven spheres. The high level of agglomeration does not promote satisfactory sintering characteristics, and can lead to porosity in the fired films


Fig. 5 This powder consists of spherical particles with l o w e r agglomeration than the powder shown in Figure 4, but it has a considerable degree of surface roughness. Although an improvement viously illustrated material, it remains unsatisfactory for MLCC applications

Over 9'"-

Fig. 6 Composed of 0.5 to 2 microns diameter smooth spheres of low agglomera- t i o n , t h i s m a t e r i a l approaches that currently p r e f e r r e d f o r MLCC applications. The variations in par t ic le size and agglomeration achieved by subtle changes in precipitation parameters can be seen by comparing Figures 6, 7 and 8

Fig. 7 This material which is made up of smaller spheres 0.2 to 0.5 microns in diameter has lower agglomeration and exhibits the desirable sintering and s h r i n k a g e p r o p e r t i e s required for MLCC manufacture

Fig. 8 Powder composed of very small spheres approximately 0.1 microns in diameter and exhibiting minimal agglomeration not only retains an acceptably low surface area to form high quality screen printing pastes but a150 allows the fabrication of extremely thin internal electrode layrrs, thus offering substantial savings in metal rosts


near future as it offers economic advantages. The assessment of a metal powder for a

particular application requires further characterisation in addition to measurements of surface area, tap density and particle size distribution. The determination of oxide layers or the presence of surface contaminants which may interact harmfully with any dielectric material requires the use of X-ray Photo- electron Spectroscopy. Transmission Electron Microscopy and X-ray Diffraction are used for the determination of fundamental crystallite size, which incidentally provides information on the particle growth mechanism. The presence of bulk impurities which can drastically alter MLCC performance is determined by X- ray Fluorescence Spectroscopy, in addition to the traditional methods of chemical analysis. Finally, Simultaneous Thermal Analysis and Dilatometry are used to examine sintering and shrinkage behaviour.

The investigations carried out at the Johnson Matthey Technology Centre have involved mainly palladium and silver-palladium, reflect- ing the importance of the platinum group metals in the manufacture of MLCC electrodes. This work has provided a better understanding of the fundamental aspects of precipitation of

Oxygen Probe for Heat-’ In earlier times steel was heat-treated by

craftsmen who depended largely upon their accumulated knowledge to ensure that the properties of the metal matched the application. Present day requirements demand more exact control, not only of temperatures but also of furnace atmospheres, for if the latter is chemically unsuitable the composition and hence the physical properties of the steel will be adversely affected.

To provide a reliable and accurate indication of available carbon in furnace gases Corning Glass Works, of Corning, New York, U.S.A., have now developed a solid state oxygen measuring probe. Somewhat similar probes find application in chemical process technology, and can assist in vehicle emission control

The Corning Glass probe includes a yttria stabilised zirconia solid electrolyte and a platinum electrode which is exposed to the

these metal powders, which can also be utilised for other applications such as improved MLCC end terminations and hybrid interconnect metallisations. The electronics industry requires and demands high purity powders of advanced formulation for existing and predicted future applications; it is knowledge gained from investigations such as these recorded here that will enable the constantly changing needs of this important industry to be satisfied.

References I J. R. Larry, R. M. Rosenberg and R. 0. Uhler,

IEEE Trans., Components, Hybrids Manuf. Technol., I 980,3, (z), 2 I I

z B. Walton, Radio Electron. Eng., 1975, 45, (3), I39 3 T. H. Lemon, Platinum Metals Rev., 1975, 19, (4),

4 G. Fisher, Ceram. Ind., April 1983, 110, (4), SO 5 K. E. G. Pitt, “An Introduction to Thick Film

Component Technology”, Mackintosh Publica- tions, Luton, I 98 I

6 N. M. Davey and R. J. Seymour, Platinum Metals

7 A. G. Walton, “Principles of Precipitation of Fine Particles”, Chapter 5 in “Dispersions of Powders in Liquids”, ed. G. D. Parfitt, Applied Science Publishers, London, 1973

146

Rm.7 1985, 29, 2

8 J. Garside, Chem. Ind. (London), I 983, ( I 3), 509 9 J. Heicklen, “Colloid Formation and Growth”,

Academic Press, New York, I 976

Treatment Furnaces furnace atmosphere. Oxygen molecules in the furnace are turned into ions by the catalytic effect of the platinum and are then conducted through the zirconia where they recombine into molecules, the electrical potential generated depending upon the difference in the amounts of oxygen inside and outside the furnace. The oxygen produced in the furnace is directly related to the concentration of carbon monoxide and carbon dioxide, and thus to the amount of carbon available for hardening steel by carburising and carbonitriding treatments.

Operating in the range 760 to I IOOOC, the probe can be used with furnace atmospheres generated from natural gas, nitrogen+methanol mixtures and propane-derived gases.

In the U.K. the Corning Glass probe is marketed by Land Pyrometers, Dronfield, Sheffield S I 8 6DJ, from whom additional information is available.

Plat inum Metals Rev., 1985,29, (4) 179

The First Experiments on Platinum CHARLES WOOD'S SAMPLES FROM SPANISH AMERICA

By L. B. Hunt The Johnson Matthey Group

The distinction of being the first man to bring samples of platinum to Europe and to carry out a few preliminary experiments on its nature and properties belongs to Charles Wood, a son of the famous William Wood, an ironmaster and the producer of the copper coinage known everafter as Wood's Halfpence.

How this important step came to be taken, and how it led to the first scientific examination of platinum and its identification as a new element involves a most curious chapter in the history of metallurgy and links two quite separate activities taking place some thousands of miles apart, the Spanish conquerors of South America and their thirst for gold with the introduction in England of the smelting of iron ore with coal or coke instead of charcoal.

The story of the Conquistadore's intensive search for gold and their insensitive melting down of huge quantities of gold objects in the sixteenth century is well known, but their penetration into the inhospitable region of the Choco, the long narrow strip of country between the main Cordillera of the Andes and the Pacific Ocean in what is now Colombia, did not occur for very many years. When finally, in about 1690, the extraction of gold from the river beds in this area began to be organised it was found that, mixed with the gold, was another whitish metal that was given the name of Platina, a derogatory diminutive of plata, their word for silver. This was considered to be worthless and was used by unscrupulous miners to adulterate the gold to such an extent that in

Charles Wood 1702-1774

Born in Wolverhampton, the sixth son of the famous William Wocid, ironmaster and the producer of the copper coinage known as Wood's Halfpence, Charles moved to Jamaica in 1736 after the failure of a scheme promoted by his rather for smelting iron with coal in Curn- berland. Here for some years he superintended a lead mine and on his return to England he brought with him the first specimens or native platinum to reach Europe and to be submitted to scientific examination rhotograph from a ponrrit m the posewon of the family by councny of M i s s Margaret Wood

PIarinum Metals Rev., 1985,29, (4), 180-184 180

1707 a governmental decree was issued prohibiting this practice. None the less small amounts were put to use and there is a record of a gift made in about 1730 to the Viceroy of New Granada of a rapier guard and a set of buckles (I). Much of this new metal however, was shipped illegally down river to Cartagena and thence to Jamaica and it is here that Charles Wood comes into the story.

William Wood, the “Irish Patentee”

To explain the career of Charles Wood we have first to give some account of the activities of his father William Wood (1671-1730). Born in Wolverhampton, he progressed to become the owner of a number of copper and iron mines in the west of England as well as rolling mills and forges. In 1722, with the support of the Prime Minister Robert Walpole and through the influence of the German mistress of George I, the Countess von Schulenberg (created Duchess of Kendal in 1719) he obtained a patent for the production of copper coinage for Ireland in return for a payment to her of E I o,ooo. The coins, halfpence and farth- ings; were struck in tGo locations, at Seven Dials in London and at Bristol, and assays carried out by Sir Isaac Newton, at that time Master of the Mint, showed that the copper “was of the same goodness and value with that which was coined for England” (2). Wood also secured a patent to produce coins for the North American colonies, these being in brass described in a contemporary journal as “a beautiful compound metal” (3).

Although there was a great deal of complaint from Ireland about the introduction of coinage from England-including the famous Drapier letters of Dean Swift who quite unjustifiably “set down gossip as gospel with figments of his own” ( 4 h t h e r e is no doubt that Wood, known afterwards as the Irish Patentee, was a thoroughly honest citizen as well as a man of considerable energy and enterprise. Unfortunately for almost a hundred and fifty years he has been confused in the literature with a quite different William Wood and thus

often labelled as a rogue. This other William in I 720 became the manager of a company called the Mines Royal1 of Jamaica, formed to operate the (non-existent) gold and silver mines in that island. This was of course a disastrous and expensive failure, associated financially with the South Sea Bubble and was not in any way con- nected with our William Wood. The confusion of the two goes back to an article in The Gentleman’s Magazine of I 852 ( 5 ) in which the anonymous author merely assumed them to be one and the same person, but there is written evidence that the “notorious” Wood was still alive and involved in litigation over his ill- founded scheme in I 746, sixteen years after his namesake’s death (6).

In 1728 William Wood turned his mind to a method of smelting iron with coal or coke instead of charcoal, a process that had already been introduced by Abraham Darby in 1709, but employing a reverberatory furnace instead of the blast furnace relied upon by Darby. With two of his sons, Francis and Charles, and one Kingsmill Eyre he petitioned the crown for a charter as Governor and Company of Iron- masters of Great Britain with a capital of one million pounds and erected a plant at Friz- ington near Whitehaven in Cumberland but his death at only fifty-nine in I 730 left the two sons in charge. Trials of his smelting process were unsuccessful and by 1733 the whole enterprise had collapsed . and in consequence Charles was gazetted bankrupt.

Charles Wood’s Appointment in Jamaica

This was the turning point in Charles Wood’s career and after a short period spent in Carolina he returned to Cumberland where, in 1735, he married Anne Piele of Buttermere. Early in the following year his fortunes improved when he was appointed to superintend some lead mines situated in Liguanea in Jamaica and “to give directions for the erecting proper furnaces to smelt the ore from the said mines and to instruct negroes in the working of the said mines and furnaces” (7). This post, carrying a salary of two hundred


pounds a year, was offered to him by a William Poyntz ( I 682-1 748) a member of a family that had for many years been associated with the West Indies, but unfortunately the life of the mine was to prove short indeed. One account of the history of Jamaica, written in I 756, records that

“lead ore likewise abounds here . . . but it is not found in any regular bodied veins which, among other reasons, obliged the gentlemen who had been engaged in the lead works of Liguanea to drop the undertaking after they had been at a great expence in building a very compleat set of works and carried on the manufacture for some time” (8).

Family records compiled by one of the great- great-grandsons of Charles, Mr. M. H. Wood, (9), show that the first child of his marriage was born in Jamaica in May 1739 while a second child arrived in March 1742 in Whitehaven, showing that somewhere between these dates he returned with his wife to England. It was during his period on the lead mines that there came into his possession some specimens of platinum, no doubt smuggled from Cartagena, and after carrying out a few preliminary experiments with them he carried them back to

William Brownrigg 171 1-1800

A native of Cumberland, Brownrigg combined a distinguished scientific career with a modest and retiring nature. After taking his M.D. in Leyden he settled down to practice medicine in Whitehaven and was elected a Fellow of the Royal Society in 1742. He became friendly with Charles Wood, who passed to him the specimens of platinum, but although Brownrigg later carried out one or two experiments on them he passed them on to the Royal Society with a letter describing their source and giving details of Charles Wood’s preliminary experiments. This communication quickly led to more extensive investigations on the properties of platinum From a ponrait painted in about 1790 lormcrly in the Board Room of the Whitehaven Hospital

England and presented them to William Brownrigg, a distinguished scientist who preferred to engage in general practice as a medical man in Whitehaven. Brownrigg was to play a vital part in disseminating the news of Wood’s findings, but not for some time to come.

Nothing is known of Charles Wood’s activities between 1741 and 1747 when he was appointed Assay Master to the Governor of Jamaica. His description as Assay Master during his earlier period in the island, so often stated in the literature, is erroneous, as the post was not created until a law was passed at Westminster stating among other things that:

“from and after the first day of September in the year of Our Lord one thousand seven hundred and forty seven it shall be lawful for the governor to nominate and appoint one or more assay masters” ( I 0).

Recent research by Mr. Robert Barker has confirmed that Wood accepted this post, while he has found a number of pieces of silverware made in Jamaica between 1747 and 1749 bearing Wood’s initials as assayer ( I I). In the latter year Wood relinquished the post, however, and again came home to England, now returning to his iron working by setting up a forge at Low Mill near Whitehaven. In this enterprise he had as his associates several


Part of the letter from William Brownrigg read by William Watson to the Royal Society on December 13th 1750. In this he refers to Charles Wood as “a skilful and inquisitive metallurgist”, going on to say that he “was not ambitious of appearing in print”

members of a family named Spedding, one of sent to Watson, William Brownrigg wrote: their sisters having married Brownrigg in I 741. It can be well imagined that Wood now prompted Brownrigg to take an interest in the specimens of platinum that he had been given some nine years earlier and this was indeed what happened. In 1742 Brownrigg had been elected a Fellow of the Royal Society after carrying out researches on “fire damp” at a time when the dangerous exhalation of methane in coal mines was unknown.

The Smuggled Platinum Samples The specimens brought home by Charles

Wood included some platinum grains mixed with black sand, some native platinum grains separated from the sand, some platinum that had been melted after alloying with other metals, and a piece of platinum that had formed part of the pommel of a sword. Now Brownrigg’s papers to the Royal Society had been read for him by his friend William Watson

“The experiments which I have related were several of them made by a friend whose Exactness in performing them and Veracity in relating them I can rely upon”.

An extract from the main communication is illustrated here, and the paper goes on to detail the preliminary tests that Wood had carried

“When exposed by itself to the Fire, either in Grains, or in larger Pieces, it is of extreme difficult Fusion; and hath been kept for two Hours in an Air Furnace, in a Heat that would run down cast Iron in fifteen Minutes: Which great Heat it endur’d without being melted or wasted; neither could it be brought to fuse in this Heat, by adding to it Borax, and other saline Fluxes. . . .

When exposed to a proper Degree of Fire, with Lead, Silver, Gold, Copper or Tin, it readily melts and incorporates with these Metals; rendering the Mixture, like itself, extremely hard and brittle.

Having been melted in an Assay Furnace, on a Test with Lead, and therewith exposed to a great Fire for three Hours,\ till all the Lead was wrought

out:

(1715-1782) and it was to Watson that he Off, the Platina was afterwards found remaining

fered any Alteration or Diminution by this finally an account of these specimens and at the Bottom Of the Test, without having

of Wood’s initial experiments upon them, . omration. - c - - - - - - - -

asking him to communicate this to the Royal Society. Watson was quick to comply with this request and On December 13th 1750 he read the letter to the Society and presented them with the specimens (12). In the covering letter

A Piece of Platina was put into strong and pure Aqua Fortis, and therewith placed in a Sand-heat for twelve Hours: The Platina, when taken out of the Aqua Fortis, was found of the same Weight as when put into it; being in no-wise dissolved Or corroded by that Menstruum.”


Thus it may be claimed that it was the enterprise of Wood in conducting preliminary experiments on smuggled platinum which he brought to England from Jamaica and the dissemination of his findings in the Philoso- phical Transactions of the Royal Society that established him as the first scientific investigator of the properties of this remarkable metal. The involvement of Watson undoubtedly hastened publication and discussion of Wood’s work throughout Europe, leading to further investigations and published papers by German, Swedish, French and Spanish scientists ( I 3).

Wil l iam Watson 17 15-1 787

Well known for his researches on electrical phenomena, Watson was elected to the Royal Society in 1741. He was a most active Fellow and i t was to him that Brownrigg passed the samples of platinum with a request that he should read the accompanying letter to the Society. Almost immediately he wrote to his friend Professor Bose of Wittenberg convey- ing to him the news of this “newly discovered metal in South America” and Bose published the account in German, so alerting scientists throughout Europe to Wood’s discovery. In the last year of his life Watson was knighted for his services to science

However the key link was provided by Brownrigg, the modest English country doctor who had the foresight to perceive that:

“Upon the whole this Senii-metal seems a very singular Body that merits an exacter Inquiry into its Nature than hath hitherto been made, since i t is not

altogether improbable that, like the Magnet, Iron, Antimony, Mercury nntl other metallic substances, it may be endowed with some peculinr Qucilities that may render i t oJ singular Use nnrl Iniportance t o Mankind”.

References

I R. C. West, “Colonial Placer Mining in Colom- bia”, Baton Rouge, 1952, pp. 63-64; W: F. Sharp, “Slavery on the Spanish Frontier”, Norman, Oklahoma, 1976, pp. 37-55

2 R. Ruding, “Annals of the Coinage of Great Britain and its Dependencies”, London, I 840, 11, P. 454

3 TheLondon Post, 1723, January 14 4 Sir John Craig, “Newton at the Mint”, Cam-

5 Anon, The Gentleman’s Magazine, I 852, I 37 6 British Museum Add. MSS 43499 and 22639

bridge, I 946, p. I I 6

7 Memorandum of Agreement, 1736, kindly lent by Air Commodore F. J. P. Wood

8 P. Browne, “The Civil and Natural History of Jamaica”, London, 1756, p. 243

9 M. H. Wood, “An Interim Report on the Wood Family Genealogy”, Privately published, I 963

10 Act of Parliament 20 George 11, xvi, I 747 I I Mr. Robert Barker, private communication 12 Phil. Trans. Roy. SOC., 1749-50,46,584-586 13 D. McDonald and L. B. Hunt, “A History of

Platinum and its Allied Metals”, Johnson Matthey, London, 1982


ABSTRACTS of current literature on the platinum metals and their alloys PROPERTIES A Scanning Auger Microscopy Study of the Influence of Platinum on the High- Temperature Oxidation of a Nickel- Silicon-Magnesium Alloy G. R. JOHNSTON, J. L. COCKING and W. C. JOHNSON, Oxid. Met., 1985, 23, (5/6)7 237-249 The oxide scale on Ni-4.4Si-o.1Mg alloy samples heated in air at I I OOOC were analysed by high resolution scanning Auger microscopy. Concentration profiles through the oxide were taken. The presence of Pt, either in contact with the alloy or in the hot zone of the furnace increased the oxidation rate by an order of magnitude in comparison with the Pt-free rate. In the absence of Pt the multi-layered oxide scale was an outer layer of Mgdoped Ni oxide, over- lying a silicate layer (Mg,Ni)2SiO4, on top of a thin interfacial layer of Si02. With Pt present the concentration of Mg in the oxide scale was below the detection limit.

Compositional Variations in the Near Surface Layers, an Atom-Probe Study of Cosegregation of Sulfur in Pt-Rh and Pt- Ir Alloys M. AHMAD and T. T. TSONG,J. Chem. Phys., 1985, 83, (119388-396 Equilibrium composition depth profiles with true single atomic layer depth resolution were obtained for the (001) plane of a Pt-Ir and five Pt-Rh alloys using the atom-probe field ion microscope. Pt segregates to the top two layers in Pt-Ir, and Rh segregates to the top layer in Pt-Rh alloys after annealing for 5 minutes at 700°C. An S overlayer segregates to the surface of these alloys, even though the bulk impurity content < I ooppm. The coverage of S overlayers for Pt-Rh alloys varies between 0.22 and 0.52 of a monolayer, and increases with increasing surface Rh.

lon-Induced Phase Formation in Metal- Silicon Systems L. S. HUNG and I. W. MAYER, Thin Solid Films, 1985, 1.233 (4, 135-144 4He ion backscattering techniques and TEM were used to investigate the interaction of ion beams with thin film structures in a number of silicide forming systems. The mixed layer was an equilibrium compound for Pd and Pt metals and an amorphous phase for refractory metals. For Pd, the Pd2Si phase grew with ion dose and remained crystalline up to high dose. Pd-Si and Pt-Si were the only systems where silicides formed and remained crystalline during ion irradiation at room temperature. Differences at liquid N2 temperatures with doses were observed.

Study on the Electrical Conductivity of Pt/ZnO Catalysts H. ZU-PEI, G. XIU-YING and L. WEN-ZHAO, J. caral. (Dalian, China), 1985,6, (I), 87-90 An in situ examination of the electrical conductivity of Pt/ZnO catalysts during or after H treatment at room temperature and >3oo0C has been performed. The electrical conductivity increased instantaneously by six orders of magnitude when PdZnO catalyst pellets were exposed to H at room temperature. But it returned to its original value if the pellet was purged with N2 or evacuated at room temperature to remove H2.

Perpendicular Magnetic Anisotropy in Pd/Co Thin Film Layered Structures P. F. CARCIA, A. D. MEINHALDT and A. SUNA, Appl. Phys. Left., 1985~47, (z), 178-180 Magnetic studies have been made of thin film periodic PdCo layered structures with ultrathin Co (4-1 3A). Films with Co of thicknesses <8A were easy to magnetise along a direction normal to the film surface. The best films had saturation magnetisation of -500emu/cm3 and a coercivity of 55oOe, and could be used for vertical magnetic recording.

The Mg-Pd (Magnesium-Palladium) System A. A. NAYEB-HASHEMI and 1. B. CLARK, Bull. Alloy Phase Diagrams, 1985,6, (2), 164-167 An assessed Mg-Pd phase diagram from o-1600°C based on several cited references is reported. A discussion of intermediate phases, crystal structure data and lattice parameter data is also presented.

The HrOz Reaction on Palladium Studied over a Large Pressure Range: Independence of the Microscopic Sticking Coefficients on Surface Condition H. M. DANNETUN, D. SODERBERG, 1. LUNDSTROM and L. H. G. PETERSSON, Surf. Sci., 1985, 152/153, (I), 559-568 The H2-02 reaction was studied on the Pd gate of a I'd-MOS structure over a large pressure range. By measuring shifts in the C vs. V curve the changes in free H atom concentrations can be monitored. These results and others indicate a critical PH2:Po2 ratio of 0.4 where the surface turns from being 0 dominated to being H dominated. The critical ratio is independent of the absolute pressures and of surface conditions and shows no temperature dependence from 5c-2oo0C. This implies H and 0 have similar sticking coefficients -at the Pd surface. This device can be used as an H sensor in a catalytic reaction over a large pressure range.


XPS Studies on t h e Surface of Amorphous Pdw,Si2, Alloys Y. 'IAKAGI, C.-H. HWANG, H. SEKIZAW'A and K. KAWAMURA, Jpn. '3. Appl. Phys., 1985, 14, (4), 390-396 The depth profiles of the chemical states and composition of Pd and Si near the surface region of amorphous Pd&20 alloys have been studied by XPS. The depth profile can be divided into three characteristic regions: bulk, transient and skin. On passing through the transient region from the bulk to the skin, the amount of Si02 increases while that of Pd decreases. In the skin, amorphous SiO coexists with metallic Pd. The chemical state of Si in this region depends on the preparation conditions.

Hydrogen Adsorption States at the Exter- nal and lnternal Palladium Surfaces of a Palladium-Silicon Dioxide-Silicon Structure L.-G. PETERSSON, H . M. DANNETUN, J. FOGELBERG and I. LUNDSTROMJ. Appl. Phys., I 985,58, (I) , 494-4 I 3 The H2 adsorption states at the external and internal Pd surfaces of a H sensitive Pd-Si02-Si (Pd-MOS) structure have been studied in high and ultra high vacuum. The steady state response of the Pd-MOS shows a logarithmic dependence on H 2 pressure. The heat of adsorption of the internal surface is coverage dependent. There are always H adsorption states available at the internal surface, independent of the applied pressure, which explains how the Pd-MOS structure acts as an H sensor over wide pressures.

Electrical Conductivity of (Bi,Pb)*MO (M=Pd,Pt) Linear Chain Compounds

and D. THOMAS,J. Phys. Chem. Solids, 1985, 46, (3), 297-299 Partial oxidation of Pd in Bi2Pd04 was achieved by substituting Pb2+ for Bi3+ up to Bil.91Pbp.P9Pd0.+. Partial oxidation is necessary to stabilrse the isostructural Pt compound Bil-,Pb,PtO, in the range 0.33 < x < 0.52. Pt compounds had relatively high conductivities (u u IolQcm) and low activation energies (-0.02eV) with small variations in x. Pd compounds had lower conductivities which increased linearly with mean oxidation degree.

Oxygen Potential and the Chemical State of the Fission Products Ruthenium, Rhodium and Palladium in Irradiated Oxide Fuels M. S. CHANDRASEKHARIAH,~. Nucl. Maim., 1985,130, 366-374 Thermodynamic properties of intermetallic compounds of the type M3U and M,Pu where M = Pd, Rh or Ru are examined. These intermetallics have unusual thermodynamic stability. The presence of these intermetallics in nuclear fuel urania-plutonia is unexplained. The critical 0 potential of the oxide fuel matrix for their formation is suggested.

N. BETTAHAR, P. CONFLANT, J. C. BOIVIN, F. ABRAHAM

CHEMICAL COMPOUNDS Redox, Ligand-Exchange, Oligomeriza- tion, and Hydrosilation Chemistry of trans-Dichloro( ethylene) ( phenazine) platinum A. R. SIEDLE, K. R. MA", D. A. BOHLING, G. FILIPOVICH, P. E. TOREN, F. J . PALENSKY, R. A. NEWMARK, R. W'. DUERST, W. L. STEBBINGS, H. E. MISHMASH and K. MELANCON,Inorg. Chem., 1985,14, (14), 2216-2223 A series of compounds of the type trans- [ami1ie)l'tC1~[C~H,) [where amine = phenazine, quinoxaline, pyrazine, phenazine N-oxide, 2,6- dimethylpyrazine, tetramethylpyrazine, acridine) was prepared by displacement of chloride from IJtC13(C211 ,).- [phenazine)PtClz(C~HJ) is an effective hydrosilation catalyst and is the source of a series of novel bimetallic Pt-phenazine complexes and of polymetallic reduction products which are accessible by a number of routes.

~~-Allylpalladium Compounds P W. JOLLY, Angew. Chem., Int . Ed. Engl., 1985, 14, (4)> 283-295 An in-depth study of the chemistry of the P d C bond is presented concentrating on ~3-allylpalladium complexes. Their preparations, structures and reactions are examined. These complexes are frequently involved as intermediates in the Pd catalysed transformations of dienes. (76 Refs.)

A Novel Giant Palladium Cluster M. N. VARGAFTIK, V. P. ZAGORODNIKOV, 1. P. STOL- YAROV, 1. 1. MOISEEV, V. A. LIKHOLOBOV, D. I . KOCHUBEY, A. L. CHUVILIN, V. 1. ZAIKOVSKY, K. 1. ZAMARAEV and G. I. TIMOFEEVA.3. Chem. SOC., Chem. Commun., 1985, (14,937-939 Various analytical techniques have been used to examine a new catalytically active cluster prepared by reduction of Pd(OAc)2 by H 2 in the presence of L = I , I o-phenanthroline, or 2,2'-bipyridine, followed by O2 treatment. The cluster produced contains a closely packed metal nucleus (570+30Pd atoms), bearing 60+3 coordinated L and 18o+1o OAc- in the outer sphere of the cluster. It is soluble in H20 and polar organic solvents, and catalytically active in the oxidative acetoxylation of ethylene by 0 2 to form vinyl acetate.

Synthesis of Novel Chiral Ruthenium Complexes of 2,2l-Bis (diphenyl- phosphino)-l,l I-binaphthyl and Their Use as Asymmetric Catalysts T. IKARIYA, Y. ISHII, H. KAWANO, T. ARAI, M. SABURI, S. YOSHIKAWA and S. AKUTAGAWA,J. Chem. soc., Chem. Commun., I 985, ( I 3), 922-924 Reactions of [RuC12(COD)],, (COD = cycl-ta-r ,5- diene) with the chiral bidentate phosphine ligands give new chiral Ru(I1) complexes Ru2C14(BINAP)2(NEt3) and Ru2C14(ptolyl- BINAP)2(NEt ,). These act as excellent catalysts.


PHOTOCONVERSION The Au/GaPc-CVFerri, Ferrocyanidel GaPc-CVPt Photoelectrochemical Cell

Am. Chem. SOC., 1985,107, (IZ), 3738-3739 A photoelectrochemical cell has been constructed based upon vacuumdeposited (chlorogllium phthalocyanine, GaPc-Cl) thin films in contact with a Au/GaPcCl anode and a PdGaPc-CI cathode, and a ferdferrocyanide redox electrolyte which acts as contacting phase between photoanode and photocathode. The work function difference between the two metals gives the driving force for the photoelectrochemical response. The resulting cell gave a photopotential response -20% of the theoretical maximum dictated by the sum of the apparent band gaps.

Energy- and Electron-Transfer Processes for the Lowest Triplet Excited State of Tetrakis( diphosphito)diplatinate( I1 )

Chem., 1 9 8 5 8 9 , (IZ), 2486-2492 Efficient transfer of excitation energy from JPt,(POP):-' was found to occur to various acceptors including naphthalene and Ru(bpy){+. Efficient formation of redox products occurs both in reductive and oxidative quenching. Intense room temperature phosphorescence, high solubility in aqueous and non- aqueous media and long triplet lifetimes make Pt2(POP):- useful as an energv sensitiser.

Hydrogen Photoproduction in a Con- tinuous Flow System with u.v.-Light and Aqueous Suspensions of RuO,/Pt/TiO,

J. Hydrogen Energy, 1985,10, (4), 221-226 H2 generation rates of up to I Io,umol/h have been obtained in a continuous gas flow apparatus for the liquid phase photolysis of water using neutral aqueous suspensions of RuOJPfli02.

W. J. BUlTNER, P. C. RIEKE and N. R. ARMSTRONG, J.

J. R. PETERSON and K. KALYANASUNDARAM,J. Phys.

R. SIMARRO, S. CERVERA-MARCH and S. ESPLUGAS, Inr.

Radiation Reduced Ir Sols: A Study of Their Catalytic Efficiency for Reduction of H 2 0 to H2 by MV+.Compared with Pt Catalysts M.4. DELCOURT and N. KEGHOUCHE, Nouv. 3. Chim.,

Ir colloids were prepared and used as catalysts to convert H20 to H2 via electron transfer from MV'.. Kinetic parameters using pulse radiolysis indicated that a fast process involves the fresh metal particles, while a slow one corresponds to a H-covered surface state. H2 production with Pt or Ir was investigated and a catalytic mechanism is proposed. The Pt and Ir metal surfaces are almost totally covered by adsorbed H atoms, the desorption of which controls the overall process. H2 desorption competes with MV2+ hydrogenation, the latter being favoured at high metal concentrations.

19853 91 (4)1 235-240

An Iridium-Bipyridine Complex as a Photosensitizer for the Bromide Oxida- tion to Bromine by Oxygen

and D. MEYERSTEIN,J. Phys. chem., 1985, 89, (12), 2460-2464 An Ir(III>bipyridine complex, [Ir(C3-N l- bpyXbpy)2]2+, was used as a photosensitiser in aqueous bromide solutions. Steady-state photolysis of oxygenated solutions by near-u.v. and visible light produces equal concentrations of B r j and H202. The quantum yield of B r j equivalents depends on pH, illumination dose and bromide concentration.

Hydrogen from Hydrogen Sulfide Cleavage. Improved Efficiencies via Modif icat ion of S e m i c o n d u c t o r Particulates

SERPONE, M. GRATZEL, L. BALDUCCI and M. VISCA, Int. J. Hydrogen E n m y , 1985,10, (4), 249-253 Visible light irradiation of CdS dispersions containing HIS in alkaline aqueous media gives efficient H2 evolution; however, an improvement is observed when the CdS particles are loaded with Ru02. A combination of Ti02 and CdS both loaded with Ru02 gives increased efficiency. The H2 evolution rate depends on the preparation conditions of CdS and TiOa For the best catalyst combination and under direct sunlight irradiation the overall conversion efficiency of solar energy is 2%.

The Effect of the Substitution of Ru for T i o n t h e E l e c t r o - a n d Photoelectrochemical Properties of Ti02 Crystals c. GUTIBRREZ and P. SALVADOR,J. Electroanal. Chem. Interfacial Electrochem., 1985,187, (I), 139-150 The photoelectrochemical behaviour of a Ru doped T i02 crystal electrode of composition Ti0.97Ru0.0302 in contact with aqueous electrolyte was investigated. The substitution of Ru4+ for Ti4+ in the T i02 has two main effects, namely sensitisation to visible light and reduction of the overpotential for 0 2 evolution.

A. SLAMA-SCHWOK, S . GERSHUNI, J. RABANI, H. COHEN

M. BARBEN, E. PELIZZETII, G. BORGARELLO, N.

ELECTRODEPOSITION AND SURFACE COATINGS Experience with Platinum Aluminide Coatings in Land-Based Gas Turbines

Temp. Technol., 1 9 8 5 3 , (2), 59-64 Two Pt aluminide coatings were applied by a two- stage process to industrial gas turbines. Hot- corrosion crucible tests with salt mixtures to simulate actual blade deposits were then performed. Sig- nificant improvement to resistance against hot corm- sion at intermediate temperatures 750450°C and against high temperature oxidising conditions of -950°C were found. Coating life exceeded that of conventional NiCrSi coatings.

R. BAUER, K. SCHNEIDER and H. W. GRUNLING, High


E l e c t r o p l a t e d P a l l a d i u m - S i l v e r (60/40wt%) Alloy as a Contact Material F. I. NOBEL, IEEE Trans. Components, Hybnb Manuf. Technol., 1985, CHMT-8, (I), 163-172 The use of electroplated 6oPd-4oAg in electronic and electrical applications is discussed. The properties of the deposits, including wearability, contact resistance, hardness and density of deposits, corrosion resistance, corrosion and preparations before use are examined. Comparisons with 80:20 Pd-Ni, Ag, Pd and hard Au are made. It is concluded the Pd-Ag electrodeposit is comparable to hard Au.

LABORATORYAPPARATUS AND TECHNIQUE New High Temperature Palladium Detectors for Oxygen Determination. Part 1. Principles and General Signal Formula of a Semi-Continuous Detector E. KOZdzOWSKI, M. BOWNIK and T. G6RECK1, Fresenius’ Z. Anal. Chem., 1985, 320, (7), 757-761 A new high temperature O2 detector which operates in repeatable cycles is described. The detector has a 1.5g thin Pd foil bed in a stainless steel chamber in which, during the first part of the cycle, H2 is made to dissolve. In the second part the sample gas flows through the bed. An instantaneous temperature rise due to the heat evolved in the reaction of the O2 contained in the sample gas with H 2 dissolved in the bed gives a measure of the O2 content. An equation for the output signal has been theoretically derived and experimentally confirmed in the range 205-45Ooc.

HETEROGENEOUS CATALYSIS On the Chemical Oscillations in Differen- tial Reactors: A Case Study of Ammonia Oxidation on Platinum P. NOWOBILSKI and C. G. TAKOUDIS, Chem. Eng. Commun., 1985,33,(1-4), 2 1 1-217 A review of the theories of the isothermal reaction mechanisms of NH3 oxidation on a heterogeneous Pt catalyst is presented. It is shown that even in a differential catalytic reactor with conversions much less than 5%, the changes of the bulk concentrations of the reacting species may drastically affect the dynamic behaviour of the reaction system; it is suggested that they may drive the oscillations.

Mathematical Modeling of Catalytic Converter Lightoff. Part 11: Model Verification by Engine-Dynamometer Experiments; Part 111: Predictions of Vehicle Exhaust Emissions and Para- metric Analysis S. H. OH and J.C. CAVENDISH,AIChEJ., 1985,31, (61, 935-942; 943-949 A transient mathematical model was developed to describe the behaviour of packed-bed catalytic converters during warmup. The predictions of the model agree very well with the results of engine dynamometer experiments for three Pt/A1203 catalysts of widely different properties. Two catalysts were surface impregnated with o.o9wt.% and o.56wt.%Pt and one was subsurface-impregnated. The model was also used to simulate the performance of a packed-bed converter during the cold-start period of vehicle emission tests. Effects of poisons on catalysts, and converter designs are examined.

Production of Hydroxylamine from Nitrogen Oxide: A Short Review G. R. TAUSZlK and P. CROCETA, Appl. Catal., 1985,

The industrial production of hydroxylamine by hydrogenation of NO in dilute H2S04 using a PdC catalyst was studied. Various aspects of this process, including catalyst composition, reaction kinetics and mechanisms, role of mass transport phenomena and the electrochemical reduction of NO, are discussed. It is concluded that more experimental work is needed to clarify the reaction mechanism and that attention to catalyst poisoning is needed. (40 Refs.)

Dynamic Behavior of Automotive Catalysts. 111. Transient Enhancement of Water-Gas Shift over Rhodium

17, (I), 1-21

R. K. HER2 and J . A. SELL, 3. Catal., 1985, 94, (I), 166-174 The responses of catalysts Rh/PdCe/A1203, PdCe/A1203 and Pt/Rh/A1203 were examined for the water-gas shift reaction in engine exhaust gases. A transient reduction in CO emission was observed over all three catalysts when they were stabilised under rich exhaust and then given a IS exposure to lean exhaust. Explanations of part of the responses were made, but lean-to-rich step response experiments gave evidence for the water-gas shift reaction.

Free Radical Formation in the Catalytic Oxidation of NH, over a Polycrystalline Pt Surface at High Temperatures G. S. SELWYN and M. C. LIN, Langmuir, 1985, I, (z), 212-2 19 The catalytic oxidation of NH3 over a polycrystalline Pt surface at 80c-1400K was investigated. Free radicals and transient species produced included NH, NH2, OH, HNO, NO2 and diatomic NH and OH. NH produced was diminished drastically by 0 2 and yielded a desorption energy of 66kcaVmol.

Characteristics and Surface Morphology Change of Modified PtRhlO Gauze of HCN Synthesis T. BACZYNSKA, M. SEWERYNIAK and J. WRZYSZCZ, React. Kinet. Catal. Lett., 1985, 17,(1), 21-25

The modification of Pt-Rhio gauze catalysts, used for HCN synthesis, by coating their surfaces with a thin film of Pt-Rh/Alz03 is reported. Comparisons in activity, selectivity and morphological changes in the catalyst surface for standard gauzes and those covered with a thin film are reported.


The Deuterium-Exchange Heaction between Water and Hydrogen with the Thin-Film Hydrophobic Catalyst H. YAMASHITA, M. MIZOMOTO and S. MATSUDA, Nippon Kagaku Kaishi, I 985, (4), 669-673 The D2 exchange reaction between H 2 0 and H2 with a hydrophobic Pt/porous PTFE catalyst as support was studied. Catalyst reactivity was measured in a trickle bed reactor at atmospheric pressure and temperature 20-70°C. Pt particles on thin film PTFE work efficiently as catalysts because the reactants were easily diffused to the active sites. The isotopic exchange rate with the thin film catalyst increased with the increase in the liquid : gas ratio and with the rise of the reaction temperature.

Colloidal Noble M e t a l Catalysts Supported on Ion-Exchange Resins

Y. NAKAO and K. KAERIYAMA, Kobunshi Ronbunshu, 1985,429 (4), 223-229 Hydrosols of Pt, Rh, Pd and Ru were prepared from aqueous solutions of the corresponding noble metal salts by NaBH4 reduction. Anion exchange resins adsorbed the colloidal particle to give noble metal catalysts for hydrogenation, while for cation exchange resins only a H-form resin adsorbed colloidal Rh and Ru to give supported catalysts. Elec- tron micrographs indicate that Rh on the cation exchange resins has more "coagulated" states than

Palladium/Polyethylenimine Catalysts G. P. ROYER, w.-s. CHOW and K. s. HATCON, J. Mol. Catal., 1985,31,(1), 1-13 The preparation and evaluation of Pd catalysts made from polyethylenimine(PEI)/Si02 composites are discussed. PEI was adsorbed on either porous SiO, beads or Si02 gel. After crosslinking, the material was loaded with base to increase surface area and availability of the polymer. PdPEI/SiO2 beads are used effectively in suspension with HCOOH acid as the H donor; deprotonation of carbobenzoxy- Glycine-0-t-butyl is very rapid compared to PdC.

Preparations of Ti02-Attached Rh Catalysts and Their Catalysis Y. IWASAWA and H. SATO, Chem. Lett. Jpn., 1985, (4), 507-5'0 The preparation of new TiO2-attached Rh catalysts is described. The catalysts were prepared by the reaction between R ~ ( v ~ - C , H J ) ~ and surface OH groups on T i 0 2 followed by chemical treatment with H2. The catalysts had higher activities for ethane hydrogenolysis and etheix hydrogenation than a conventional impregnated Rh catalyst. The most active catalyst was the mononuclear Rh hydride species. The surface structures of these catalysts have no analogues with homogeneous and conventional heterogeneous catalysts, and may be typical examples of a new class of catalysts.

on the -anion exchange resins. Two mechanisms for the adsorption are presented. Catalytic activity is higher for cation exchange resin. Ammonia Synthes i s of Severa l

Preparation and Catalytic Act iv i ty

Ruthenium Supported Catalysts

and Khodium Supported Catalysts Anorg. Allg. Chem., 1985,522,235-240 G. A. DEL ANGEL, B. COQ, G. FERRAT, F. FIGUERAS and s. Supported Ru catalysts were prepared from FUENTES,SU?$ SCi., 1985, 156, (2), 943-95 1 RuCI3.3H20 and K4[Ru(CN)6].3H20 solutions, upon Some reactions involving C-H, c-c, cCI and c-o several acidbase pretreated ~A1203 samples, using bonds were investigated on Rh and Pd supported water and acetone as solvents. An increasing Ru

content of the catalysts with increasing acid site catalysts in relation to the metallic structure. Generally there is a structure insensitivity for Pd, content Of the is Observed, when

active than large particles when Si02is the support. prepared from K4[Ru(CN)61.3H20 were about ' O fold more active than those prepared from

Some (:atalytic Properties of Palladium P. RAMIREZ DE LA PISCINA, N. HOUS and I. E. SUEIRAS,Z.

but not for Rh. For Rh, small particles are K4[Ru(CN)61.3H20 is as a precursor- Catalysts

Synthesis Gas Conversion Utilizing Mixed Catalyst Composed of CO Reducing Catalyst and Solid Acid. IV. Selective Synthesis of C,, C,, and C, Paraffins from Synthesis Gas

K. FUJIMOI'O, H. SAlMA and H. TOMINAGA, 3. Catal., 19853 94, ( I ) , 16-23 Synthesis gas could be converted selectively to C2-C4 paraffins with hybrid catalysts of Pd/SiO2 (methanol synthesis catalyst) and Y-type zeolite. Best conditions were 300-35o"C and i.o-5.rMPa. A hybrid catalyst containing a steam-treated high SiOt Y-zeolite gave C2C4 paraffins with a selectivity >85%, with almost no aromatic hydrocarbons and coke with CH4 selectivity of 2% or less, while CHjOH conversion on the zeolite gave aromatic hydrocarbons and coke with selectivities of 30% and I 170, respectively.

RuCI3.3H20. The more active cataljst was sensitive to acid pretreatment of y-AI2O3, while those prepared from RuC13.3H20 were not.

HOMOGENEOUS CATALYSIS Carbonylative Cross-Coupling Heaction of Aryl Iodides with Alkylaluminums by Palladium Complex Catalysis Y. WAKITA, T. YASUNAGA and M. K O J I M A , ~ . Organomet. Chem., 1985,288, (3), 261-268 Secondary and/or tertiary alcohols and unsym- metrical ketones have been obtained in moderate to good yields by Pd catalysed carbonylative coupling of aryl iodides with alkylaluminium compounds under very mild conditions. The type of reaction product depended on the kind of Al reagent used.


Homogeneous Catalytic Hydrogenation of S o y b e a n Oi l : P a l l a d i u m Acety lacetonate S. KORITALA, J. Am. oil Chem. soc., 1985, 63, (3), 517-520 Soybean oil was hydrogenated with Pd acetylacetonate at 6c-170°C, 15opsi H2 pressure and I-6oppm Pd. The best linolenate selectivity was found at 8c-12ooC. At 12ooC Pd acetylacetonate hydrogenated faster than the P d C catalyst. Trans isomerisation with the homogeneous catalyst was much higher than with PdC.

Homogeneous Catalysis of the Water Gas Shift Reaction by (Polypyridine) Rhodium Complexes D. MAHAJAN, C. CREUTZ and N. S lh IN, Inorg. Chem.,

Homogeneous catalysis in the water gas shift reaction under mild conditions (<roo0C and Iatm CO) was achieved with several @olypyridine)Rh(I) complexes as catalyst precursors in alcohol-water mixtures. Complex Rh(bpy)l was the most active catalyst precursor (-3 turnover& at 9ooC).

Rhodium Complexes as Catalysts for Hydrosilylation Crosslinking of Silicone Rubber M. HEIDINGSFELDOVA, J. Appl. Polym. Sci., 1985, 30, ( 9 7 1837-1846 The vulcanisation of a Si rubber compound, based on polysiloxane-containing vinyl and Si-H groups catalysed by [RhCI(C0)2]2, [RhCI(C2H4)212,

and Rh(acac), (1,5COD =~,~-cyclooctadiene, NBD = nornbornadiene, acac = acetylacetonate) was studied. Effect of solvent, the cross-linking density of the rubber, sol content, vulcanisation times and catalysts were examined.

I 9857 24, (1 3), 2063-2067

[ R ~ C I ( I , ~ C O D ) I ~ , [RhCI(NBD)l2, RhCI[P(C6Hd3]3,

FUEL CELLS Electrode Designs and Concepts for Bipolar Alkaline Fuel Cells K. KORDESCH, J. GSELLMANN and R. D. FINDLAY, Int. J .

The construction and production of mass produced alkaline fuel cells are described. The multiple layer electrodes used in alkaline electrolytes, and alkaline and acidic electrolytes are discussed. All use PdC with various amounts of Pt in their construction.

A Chemically Regenerative Redox Fuel Cell. I1 J. T. KUMMER and D.G. OEI, J. Appl. Electrochem.,

Redox fuel cells with V2+/V3+ and Mo3+/Mo4+ redox couples as the anolyte and a NO-JNO catalyst system for V02+ oxidation were examined. Highly acidic (-3M H2S04) molybdate solutions were readily reduced by H2 using Pt or Pd as catalyst.

Hrdrogen Energy7 19853 10, ( 5 ) s 317-324

1985, IS,(4), 6 1 9 4 2 9

ELECTRICAL AND ELECTRONIC ENGINEERING Tungsten-Platinum Alloy Schottky Barriers on n-Type Cads T. OKUMURA and K. N. TU, Appl. Phys. Lett., 1985,47, (11942-44 Alloys of W and Pt were studied as Schottky contact materials in n-type GaAs. Schottky barrier heights for W5oPt~o and W8J'tzo were measured, and were found to be 0.90 & 0.02eV by C-V and photoresponse techniques, and did not change with annealing at 35Ooc for 20h. However the value from the I-V technique changed from -0.6 to 0.7 eV upon annealing. WjoPt~o was the more stable on GaAs.

Platinum Intermetallic Resistors for CaAs-Based Circuits S. TIWARI and W. H. PRICE, Electron. Lett., 1985, 31,

(1013 429-430 A simple technique for making GaAdPt intermetallic resistors of sheet resistance -25ra/a is described. The resistors were made by reacting a 3ooA Pt film with GaAs and then sintering. X-ray diffraction identified PtGa and PtAs2 in all samples, and PtGa2 in samples annealed at 45oOC. The TCR was -9.2 x 104/OC at 25OC, and the resistors were stable up to current densities of ro'iVcm2.

Properties of Electroplated Noble Metal Layers as Contact Materials for Switching Contacts H. GROSSMA", M. HUCK, G. SCHAUDT and F. J. WAGNER,Merall, 1985, 39, (7), 619-623 Various electrodeposits of 5pm and I opm thicknesses on non-precious metals were tested on a model device as materials in switching contacts in relays and keys. The resistance of the electroplated contact layers was related to their hardness. Electrodeposits were tested at various electric load conditions: 28-55omA DC at I 2V and 24V. For loads of I 2V/12mA and on a layer thickness of 5pm the following number of operations were possible: AuCo 5 x 104, AuPd6Cuz 5 x I O ~ , Pd, PdNi20 - 107, Rh> 10'.

Electron Emission and Surface Composition of Osmium and Osmium- Tungsten Coated Dispenser Cathodes

Sci., 1985,20, (4), 429-456 D. BRION, J.C. TONNERRE and A. SHROFF, Appl. surf.

The surface composition of impre ated cathodes with coatings of pure 0 s 5c-30,ooo~thick or mixed 0s-W coatings (10-70% 0s) were measured by AES, during activation and short duration ageing at I OOO'CB (degrees Celsius brightness). During activation of cathodes with pure 0 s coatings (>3oooA) the W diffuses into the 0 s until saturation of the 0 phase occurs throughout the coating depth. Electron emission from cathodes coated with pure 0 s is three times greater than that of "type S" cathodes, whatever the coating thickness. Electron emission from mixed- coated cathodes is slightly less than that of pure 0s.


NEW PA TENTS METALS AND ALLOYS Blanks for Coins and Medals DEGUSSA A.G. European Appl. I 39,902 Pt, Pd, Au, Ag and alloy blanks have better flow properties during shaping, such as striking, when the blanks have a porosity of 8-35 vol%, preferably 10-25 ~01%. This may be achieved by creating the blanks from metal powders.

Single Crystal Alloys ROLLS-ROYCE LTD. US. Patent 4,488,915 Single crystal castings are made from specified Ni alloys containing I-4% Mo and/or Ru.

Hydrogen Storage Material

A Hz storage material consists of a substrate such as Mylar film coated with an amorphous binary alloy of (a) Fey Co or Ni and (b) a lanthanide metal and then with a film of Pd.

Diffusion Membrane

U.S. SECRETARY OF THE NAVY U.S. Patent 4,489,049

KERNFORSCHUNGSANLAGE JULICH G.m.b.H. U.S. Patent 4,496,373

A diffusion membrane for separating HZ from gas mixtures consists of (a) a foil of Ta, Nb, Ti, V and/or Ni saturated with Cu, Ag or Y as in (b), and coated on the gas-access side with (b) an alloy of Pd with at least 45 at.% Cu or 50 at.% Ag or 7 at.% Y.

Brazing Alloys G.T.E. PRODUCTS CORP. US. Patent 4,497,772 Improved ductile brazing foils are made from Cu-Ni with 0.05-5% Ti, V and/or Zr and 5-3056 Pd.

ELECTROCHEMISTRY Amorphous Alloys for Electrodes DAIKI ENGINEERING CO. LID. AND K. HASHIMOTO

British Appl. 2,146,660A A surface activated amorphous alloy for use as an electrode in electrolysis consists of: 10-30 at.% of P and/or Si of which up to 7 at.% may be substituted with B and/or C, and 90-70 at.% of a metallic component comprising at least 20 at.% Pd and 20-50 at.% Ru, Rh, Ir and/or Pt. The electrodes may be surface activated by diffusing Zn into the surface and then leaching the Zn from the surface.

Reference Electrodes U.K. ATOMIC ENERGY AUTHORITY

Erinih Appl. 2,148~51 IA A Pt wire is used in a reference electrode suitable for measuring electrochemical potential in a pressurised and/or heated system. Short-comings of known Ag/AgCI and Pd alloy thimble H reference electrodes are discussed.

Light-Assisted Electrolysis TEXAS A. & M. UNIVERSITY U.S. Patent 4,501,804 In an apparatus for water electrolysis with the assistance of solar radiation, the photocathode is a p-type Si body coated on at least one side with a catalyst chosen from Pt, Ni, Ag, Au, CoMoO4 and NiMo04, and the photoanode is an n S i body coated on at least one side with a film of SiOz doped with Pt, Pd, Rh, Ru, Te, Coy Ni or Au.

Electrode for Electrolysis IMI KYNOCH LTD. US. Patent 4,502,936 An anode of improved durability, especially in the low temperature electrolysis of brines consists of a Ti substrate coated with a sub-stoichiometric oxide of a metal such as Ti or Ta and then with platinum group metal(s) or oxide($.

Oxygen Ionisation B. WERTZ German Offen. 3,401,378 The offensive odour produced by ionisation of gaseous O2 is reduced when at least one of the electrodes is made from or coated with Pt or Au.

ELECTRODEPOSITION AND SURFACE COATINGS Catalyst System, Especially for Electroless Metal Deposition ROHM & HAAS CO. European Appl. 141,528 A reaction on a surface is catalysed by applying to the surface a monolayer of a positively charged polymer whose particles are less than p m in size. The polymer contains, in finely dispersed form, an active agent able to participate in or catalyse the reaction on the surface. The active agent may be a platinum group metal, Au or Ag, among others.

Transfer Metallisation of Dielectrics INI'ERNATIONAL BUSINESS MACHINES COW.

European Appl. I 44,046 An appropriate layer of a metal such as Pt, Pd, Rh or Ni is applied in a pattern to a polyvinyl butyral resin layer on a polyester film support. The butyral layer is placed next to an unsintered dielectric substrate provided with a pattern of M o or W. The polyester film is stripped off and the metal sintered on to the substrate, destroying the butyral resin.

Solderable Palladium-Nickel Coatings E. I. DU PONT DE NEMOURS & CO.

European Appl. I 46, I 52 A permanently solderable electroplated coating is formed on conductive surfaces by depositing a first layer of 46-82 at.% Pd and 18-54 at.% Ni. This is covered by a continuous second layer of 96-100 at.% Pd and 0-4, at.% Ni having a thickness of up to 2 nm. Metal ammine salts are used in the electrolyte.


Palladium Electroplating OM1 INTERNATIONAL CORP. U.S. Patenr 4,487,665 A bath for the electrodeposition of white Pd preferably contains, per litre, 0.1-209 Pd as Pd(NH3)z- C12, 25-12og ammonium sulphate, o.g-sg benzaldehyde-o-sodium sulphate, 0.1-1 g Ni sulphate or Ni ammonium sulphate and 2.5-15g CI ions as KCI.

Palladium Electroplating Bath W. C. hERAEUS G.m.b.H. U.S. Patent 4,491,507 Bright Pd coatings free from pores and fissures and having a low internal stress are produced by electrodeposition from a bath containing, per litre, 5-10g Pd as Pd(NH3).,Br2, rc-ISogNH4Br, 10-15og sulphamic acid andor ammonium sulphamate and 1-209 nicotinic acid andor 0.1mg4.5g niacinamide and operating at pH 6.5-10.

Electroless Plating BAYER A.G. German Offen. 3,326,508

Oxygen-Pumping Device FORD MOTOR CO. US. Parent 4,487,680 An 0 sensor for use in the exhaust system of I.C. engines consists essentially of a Z r 0 2 solid electrolyte stabilised with Y or Ce oxide and provided with catalytic electrodes of Pt, Rh or Pd.

Chlorine Detector UOI' INC. US. Patent 4,492,614 A solid-electrolyte concentration cell for detecting CI2 in gas samples incorporates Au wire leads and a catalyst for the ionisation of C12 which is Pt, Pd 01' one of their alloys.

Gas Sensor GC ININJS'I'KIES U.S. Patenr 4,498,970 In a specified electrochemical gas sensor the sensing element which consists of Pt powder compressed on to a film of Teflon is attached to a Pt connecting wire by means of a Au-filled epoxy resin adhesive.

Non-conductive substrates are activated for partial electroless metal plating by selectively spraying the HETEROGENEOUS CATALYSIS

~ - . area to be coated with an organic complex of Pt, Au, Ag or Cu but preferably Pd. Dissolved Oxygen Removal

WESIINGHOUSE ELECI'KIC CORP.

LABORATORY APPARATUS AND TECHNIQUE Electrochemical Gas Sensor ALLIED CORP. European Appl. 138,161 A sensor particularly intended for detecting H2S has an electrochemical cell with a Pt reference electrode, a Pt or Au sensing electrode and a C counter electrode.

Silane Gas Sensor NOHMl BOSAI KOGYO CO. LTD. European Appl. I 39, I 39 A silane-sensitive element in a sensor for detecting low concentrations of silane gas in air consists of an electrode-equipped alumina porcelain tube coated with a mixture of Pt, SbOCl and Sn02, which is then calcined and exposed to a silane atmosphere to stabilise its properties.

Engine Intake Air Flow Measurement NIPPONDENSO CO. LTD. European Appl. I 44,027 A Pt wire resistor is placed in the path of the intake air of an engine to sense the change in temperature caused by the air flow and thus measure the flow rate.

Milk Coagulation Detection SNOW BRAN[) MILK PRODUCTS CO. LTD.

European A P P ~ . 144,443 The state of coagulation of milk is detected by insert- ing a fine metallic wire preferably of Pt into the milk and passing a current continuously or intermittently. The change in temperature of the wire is a measure of the coagulation.

European Appl. 140,587 An aqueous medium containing dissolved 0 is mixed with hydrazine and contacted with a bed of Pd or Pt metal catalyst deposited on a solid carrier. The reaction with hydrazine reduces the 0 to below 10 ppb.

Hydrocarbon Processing Catalyst MOBILE OIL CORP. European Appl. 140,608 Heavy oils are simultaneously hydrocracked and dewaxed in the presence of a zeolite beta-zeolite X or Y mixture, optionally lanthanide-exchanged, supporting Pt, Pd, Ir, Rh or another catalyst.

Hydrogen Isotope Exchange Catalyst AI'OMIC ENERGY OF CANADA LTD.

European Appl. 141,596 A catalyst structure consists of Pt or another Group VIII metal deposited in crystallite form on a hydre phobic, high surface area, crystalline SiOz lattice and the whole provided with an outer, porous membrane coating of organic polymer, such as PTFE. The preferred support is silicalite.

Partial Catalytic Combustion in a Gas Turbine TOSIIIBA K.K. European Appl. I 44,094 A reduced NO, content in a fuel gas combustion product is achieved by partial catalytic combustion. Fuel and air are mixed and passed over a packed catalyst such as Pd at a temperature below the ignition temperature of the mixture. The product is mixed with fresh fuel and burnt in the absence of a catalyst. The catalyst may be an A 1 2 0 3 honeycomb impregnated with a La salt solution and then with a Pd salt solution.


Synthesis Gas Production Catalyst Hydroformylation Catalysts SUDCHEMIE A.G. European Appl. 144,506 MOBIL OIL Co. U S . Patent 4,487,972 A catalyst for the production of synthesis gas or Hz Aldehydes and alcohols are formed by the reaction of from aqueous methanol is equally good for cracking olefins with synthesis gas in the presence of a or steam reforming and consists of a platinum POUP polymer-bonded complex of Ru, Co but preferably metal or metals supported on either (a) T i02 or Ce02 Rh. mixed with other refractory oxides andor hydraulic binders or (b) Ti oxide applied to an A1203 or other Fuel Production Catalyst support. Pt, Pd and Rh are the preferred catalysts. GULF RESEARCH & DEVELOPMENT co.

Exhaust Gas Treatment Catalyst SIX. PRANCAISE DES PRODUITS POUR CATALYSE PRO- CAI’ALYSE European Appl. 145,584 The catalysts are particularly intended for I.C. engine exhaust gases and have a conventional composition but the major part of the active platinum metal-transition metal mixture is introduced into the inert material forming the catalyst carrier and only the residual active metal is added at the final impreg- nation stage. In an example A1203 is mixed with Pd, Ce and Fe salts, fired to give spheres and the spheres are then impregnated with Fe and Ce salt solutions.

Removing Carbon Particles from Exhaust Gases .I’OKYO ROKI CO. LTD. European Appl. 146,287 Black fumes from a diesel engine are trapped in a filter and the C particles are removed by oxidation in the presence of an injected catalyst, preferably a Pd, Pt, Cu or Ni compound.

Palladium-Rhenium Hydrogenation Catalyst E. I. DU i’ow DE NEMOURS & co.

European Appl. 147,219 A new catalyst consists of 0.5-10% Pd and I-10% Re on a C support where the active metals are present in the form of very small crystallites. It can be used in the hydrogenation of maleic acid to tetrahydrofuran and butyrolactone.

Noble Metal Catalyst Production VEG-GASINSTITUUT N.V. European Appl. I 47,839 A catalyst containing metallic Pt, I’d, Au, Ag or Cu in finely divided form as “basis metal” and at least one Group VIII active metal on a refractory support

U.S. Patent 4,493,905 A catalyst for the conversion of synthesis gas to diesel fuel consists of finely divided A1203 impregnated with Ru, Co and T h or La and is prepared by a specified procedure.

Synthesis Catalyst STANDARD OIL CO. U.S. Patent 4,496,666 A catalyst for the production of CH4 and methanol from synthesis gas consists of an A1203 andor SiO2 carrier supporting a mixed oxide of general formula M,M’bRuOx, where M is Na, K or Rb, M’ is Pt andor Pd, a is 0.002-2 and b is 0. I- I 0.

I.C. Engine FORD MOTOR CO. US. Patent 4,499,863 In a process for running an I.C. engine on methanol fuel, at least part of the methanol is decomposed to CO and H2 over a catalyst which is Pd, Pd-Pt or Pd- Rh.

W-Containing Three-Way Catalyst JOHNSON MAITHEY P.L.C. U.S. Patent 4,500,650 A catalyst for the purification of exhaust gases from I.C. engines consists of (a) a monolithic flow-through carrier, (b) a refractory oxide coating such as a washcoat of Al2O3 and Ce oxide, (c) Pt, Pd and/or Rh and (d) W or W oxide. This catalyst gives improved oxidation of hydrocarbons and reduced NH3 formation.

Hydrogenation of SBR Copolymers JOHNSON MAITHEY P.L.C. U.S. Patent 4,501,685 A catalyst for the selective hydrogenation of aliphatic unsaturation in copolymers also containing aromatic groups consists of a non-porous C black carrier supporting 0.1-5% Pd and treated with a poison such as an amine, mercaptan or P oxyacid.

is produced by contacting the catalyst containing the basis metal with one or more carbonyls of different Group VIII metals at above IOOOC to pro- U.S. Patent 4,501,824 ELTECHSYSTEMSCORP.

duce an alloyed metal on the catalyst support. Catalysts for the production of C102 from Na The catalysts can be used for methanation and chlorate and H g 0 4 acid consist of (a) a valve metal the Fischer-Tropsch reaction. oxide, such as Ti02, and (b) mixed oxides of

platinum group metals, preferably Ru oxide with Rh Fuel Activation in I.C. Engines oxide andor Pd oxide or Rh oxide and Pd oxide or Ir OlTrlMIZER LTD. European Appl. 149,688 oxide and Rh oxide or Pt oxide. The consumption of fuel in an engine is reduced by “activating” it, before it reaches the engine, in a Rhodium heated chamber filled with pellets coated with a S~rANDARDolLCo. U.S. Patent 4,504,684 noble metal catalyst, preferably in two different con- Catalysts for the hydroformylation of olefins to centrations. Typically A1203 pellets supporting Pt at aldehydes consist of a SiO2 carrier and a polymeric a concentration ranging from 0.1-1 % are used. Rh complex such as [RhCI(CO)Ph2PC6H4PPh21m


Treatment of Effluent Gases from Nitric Acid Production HOECHSI' A.G. German Offen. 3,326,639 The NO2 content of off-gases from HNO3 acid plants is reduced by reacting the gases with ethylene at comparatively low temperature (30-230'c) in the presence of a Pt/AI2O catalyst.

HOMOGENEOUS CATALYSIS Silicone Release Compositions GENERAL ELEC'I'RIC CO. British Appl. 2, I 5 I ,243A Complexes of Ru, Rh, Pd, Os, Ir and Pt are used as hydrosilation catalysts during the production of organopolysiloxanes having acrylic functionality for use in U.V. radiation-curable release coatings.

Hydrogen Production from Water COMMON\Y'liAL'I'H SCIENI'IFIC & INDUSTRIAL RESEARCH ORGANISAI'ION European Appl. I 38,627 H2 is produced in the solar radiation of water by the interaction of an electron transfer agent with hydronium ions and a Pt catalyst in the presence of a sensitiser, such as the tris (2,2'dipyridine) Ru (11) dication, which captures solar radiation.

Methyl Formate Production BPCHEMICALS I ~ m . European Appl. 149,564 Methanol is reacted with a H acceptor in the presence of a platinum group metal catalyst to yield methyl formate. The acceptor may be an aldehyde, ketone or olefin. The catalyst may be an inorganic, organic or organornetallic derivative of the metal which is preferably Ru. In the examples the catalyst is a Ru chloride-phosphine adduct or pentamethylcyclopentadienyl ruthenium chloride.

Rhodium Acetate in a Catalyst System L>AVY McKEE (LONDON) LrD. US. Patent 4,496,769 An olefin-hydroformylation catalyst consists of [Rh(OAc)2H20]2 and a tertiary phosphine such as PPh3, which is continually replenished.

Catalyst System EXXON RESEARCH & ENGINEERING CO.

U S . Patents 4,496,778179 The formation of diols from olefins, 0 2 and water is catalysed by a system consisting of OsO,, CuBr2 and an aromatic or cycloaliphatic amine such as pyridine or I ,4diazabicyclooctane.

FUEL CELLS Fuel Cell ELECTROCHEMISCHE ENERGIECONVERSIE N.V.

European Appl. 149,479 Unlike known fuel cells, this new cell is deliberately designed to have an internal leakage current. Its cathodes and anodes contain platinised C particles.

Fuel Cell Catalyst INI'EKNAI'IONAL BLISINESS MACHINES CORP.

US. Parent 4,490,~ I 9 A catalyst for use in a fuel cell consists of a substrate, such as C, coated with a "twodimensional" thin film formed of flat, isolated crystallites of Pt, Pd or Ag.

Gas-Diffusion Electrode l<l~' l~ECli SYSI'EMS CORP. US. Parent 4,501,803 A porous gasdiffusion electrode suitable for use in fuel cells, for example, and having Ru as its pre- dominant electrocatalyst, is conditioned for operation as a H-consuming anode by connecting it as cathode in a suitable electrolyte until it drops below the reversible H potential and evolves HI.

CORROSION PROTECTION Corrosion and Fouling Prevention MI 1 SllBlSIll JLJKOtiUO K.K. European Appl. 145,802 In a process for preventing fouling and corrosion of an underwater structure, a DC voltage is applied to a Pt-plated T i electrode or an anode such as a Pb-Ag alloy to make the structure anti-corrosive.

Cathodic Protection Anode OKONZIO IIE NORA S.A. European Appl. 147,505 Ti, Nb or 'Ia plated with Pt may form the basis of a new form of flexible ground anode.

Cathodic Protection Anodes KAUCHEtM C O K P . European APPl. '47,977 A I't or Pt-coated wire is used to form anodes for the protection of reinforcing rods in concrete.

CHEMICAL TECHNOLOGY Lubricant Additives I'IINN\Y;'AI. I' CUHI'. US. Parenr 4,497,7 I 9 Additives for maintaining the antiwear properties of lubricants at extremely high pressures are complexes of 3,j-dimercapto- I ,2,.+-thiadiazoles with Pt, Pd, Cu, Zn, Sn, Mo, Co, Ni, Ag or Au.

ELECTRICAL AND ELECTRONIC ENGINEERING

Gas Sensor Construction NGK SI'AKK I'LUti CO. 1.I'll. European Appl. I 40,340 The bonding of metal films to the surface of a ceramic substrate in a gas sensor is enhanced by forcing particles of ceramic into the substrate surface bef'ore the metal is applied. The adherence achieved is better than with an electrolytically roughened surface. 'Ihe ceramic may be zirconia and the film may consist of Pt, Au, etc., applied in a comb or spiral electrode pattern. The sensor is especially an 1.C. engine exhaust gas sensor.


Radio Wave Shielding Material BKII)GI<SI'ONE COKP. European Appl. 140,664 A shielding material consists of a foamed plastic body having a three-dimensional skeleton chemically plated with Pt, Au, Ag, etc.

Gyroscope of Reduced Sensitivity BKI 1 ISH AEKOSI'ACE P.L.C. European Appl. 142,937 Pt-Co or Sm-Co permanent magnet torquers may be used in gyroscopes having a means for correcting its temperature sensitivity.

Optical Fibre Cable 'I El.EI'ImNE CABLES [:ID. European Appl. 142,961 Transfer losses on ageing occur in optical fibres by the gradual absorption of Ha This is now avoided by introducing into the cable a H trapping material selected from Pd, Zr, Ti and/or MnOb

Programmable Thick Film Networks CEN'I KALAB INC. European Appl. 143,493 Attenuators, voltage dividers and the like are made from a substrate screen printed with a dielectric glaze and a thick film conductor in the form of a fusible link straddling the glaze and coated with a further layer of glaze. If high energy is released to the fusible link the second glass layer will rupture releasing the conductive material and resulting in a high post fusing resistance. The preferred fuse element consists of Pd-Au optionally combined with Pd-Ag.

Ferromagnetic Material for a Magnetic Head H I I'ACHI Ll.1). European Appl. 144,150 A marked increase in recording density is achieved with a head made from an alloy containing Fe, 2-1 2% Si and 5-25% of at least one of Pt, Pd, Ir, Rh, Ru, Au and Ag, such as an alloy of Fe with 6.5% Si and 10% Ru.

Getter Pumps for High Vacuum Pumps 5IEMBNS A.G. European Appls. I 44,522123124 Pt, Pd, Ce and their alloys are among the metals which may form the getters in a new design of getter pump.

Fusible Link in an Integrated Circuit MONOLI'I'HIC MEMOKIES INC. European Appl 146,688 Consistency in operation and lower fusing temperatures are obtained in circuits having a fusible link structure made from a Pt-Si alloy, preferably containing 23&2.3% Si.

Solar Insulating Window Film OI'I'ICAL COAI'ING LABORATORY INC.

European Appl. 149,105 A multilayer film composite has a plastic base coated with Pd, Ni and/or their oxides, Pd, Cu and Ni, Cr and/or their oxides and/or sulphides.

Sparking Plug NII'I'ONI)ENSO CO. L I'D. US. Patenr 4,488,081 Crack formation on the centre electrode of a sparking plug is reduced by joining a Pt-Ir alloy containing 15-30% Ir to the sparkdischarge portion of the centre electrode and a Pt-Ni alloy containing 15-30% Ni to the sparkdischarge portion of the ground electrode.

Electric Contacts G. RAU Gm.b.H. & CO. German Offen. 3,335,274 In a specified procedure for making electric contacts, shaped mixtures of metal powders or filaments are heat treated to form homogeneous alloys. Mixtures of Pd and Ag are preferred.

Electric Switch Contacts German Offen. 3,335,597

An electric switch for use at low current densities consists of Mo leads, one terminal of which is coated with a Pt alloy containing I - 1 0 % W, and the other with a Ag alloy containing I - I O % Cu.

SIEMENS A.G.

MEDICAL USES Surgical Clip W'. M. KIKSCH, YONG HUA ZHU, K. B. CUSHMAN

Britzih Appl. 2, I 50,440A A surgical microclip, particularly adapted for microvascular anastanoses, is preferably made of a noble metal such as Pt, Au or Ag.

Temperature Monitoring Catheter AMEKICAN HOSI'II'AL SUPPLY European AppL I 44, I 25

A helically wound, bifilar electric wire coil is embedded in the thermistor of a catheter used to monitor body temperature. The wire may be made of Pt, Au, Ag or Cu.

Treatment of Meningitis \Y'BI.I.COME FOUNDATION LID.

European A M . 145,359 Cerebrospinal meningitis may be treated with a Ru of Al complex of a bacterial capsuler polysaccharide containing sialic acid.

Implantable Electrode SIEMENS A.G. European Appl. I 47,7 I o The medical electrode is produced by sputtering Pt or Pt-Ir on a glass carbon target.

Oral Anticancer Compositions JOHNSON MAI"1IiEY P.L.C. European Appl. I 47)926 New agents for oral administration have the structure ABPtXYZ2, where A and B are ammine or the same or different alkylamine, X and Y are the same or different and represent halide, pseudohalide or, together, cycloalkane dicarboxylate (with certain exclusions) and Z is halide or hydroxy (if present). A typical compound is cis-(PtCI;(NH 3XPrNH 211.


AUTHOR INDEX TO VOLUME 29 Page

Abraham, F. 186 Abruna, H. D. 133 Adzii, R. R. 88 Ahmad, 1. 87 Ahmad, M. 185 Akpolat, H. 36 Akutagawa, S. 186 Albers, M. 0. 138 Alcacer, 1. 86 Alimova, L. YA. 36 AIDer. H. 42, 137 . . Amundsen, A. R. Anastasuevif, N. A. Andrieu, J. Anson, F. C. Apple, D. C. Arai, T. Armstrong, N. R. Arvia, A. J. Ashraf, C. Aspnes, D. E. Aubke, F. Austin, D. S. Azuma, H.

Baba, R. Baczynska, T. Baeshov, A. Bagotzky, V. S. Balducci, L. Bandyopadhyay, D. Bandyopadhyay, P Barben, M. Bard, A. J. Barkova, A. P. Barton, J. K. Basset, J. M. Bauer, R. Baumgartner, M. Bazela. W. Beden, B. Bilanga, G. Bell, A. T. Berzins, A. R. Besley, L. M. Bettahar, N. Bhaduri, S. Bi z.-c. Bidan, S. Bird, A. 1. Bless, P. Bohling, D. A. Boitiaux, J.-P. Boivin, J. C. Bomback, 1. L. Bond, G. C. Borgarello, G. Borsub, N. Bottger, D. Bottomley, F. Bownik, M. Brace, G. Brady, K. A.

1

87 88 41 88 91

186 187 87 87 86 38

132 131

133 188 38

133 187 42 42

187 88 40 87 90

187 155 37

132 16

I l , 136 175

11, 138 186 87 39 39

162 91

186 114 186 136

18, 162 187 39

106 87

188 42 91

Braga, D. Brion, D. Brunschwig, B. S. Buckingham, J. Buell, S. L. Burgan, C. E. Buttner, W. J.

Cabelka, T. D. Cameron, D. S. Campion, A. Carcia, P. F. Cavendish, J. C. Cervera-March, S. Cervino, R. M. Chakravorty, A. Chance, J. M. Chandrasekharaiah,

Page 132 190 I34 I30 134

1 1 187

132 107 88

185 I88 187 87 42 91

M. S. Chatt, 1. Chauvin, Y. Chevalier, B. Cho. P. Chou, P. Chow, W.:S. Chuvilin, A. L. Ciardelli, F. Clark, J. B. Claudel, 8. Cleare, M. J. Clegg. W. Cocking, J. L. Cohen, H. Colis, E. Collas, N. Commaeuc, D. Compie, C. Conflant, P. Coq, B. Cosyns, J.

131,186 I26 90 37

134 86

189 186 137 185 41 72 87

17, 185 187 87

132 90 37

I86 I89 I14

Cottington, 1. E. 11, 16.27, 29, 56,80, 106, 167, 179

Coughlin, R. W. 40 Cox, D. M. 90 Cresto, P. 43 Creutz, C. 134, 190 Crocetta, P. 188 Cross, R. J. 130 Crowell, J. E. I3 1 Cunningham, 1. 41

Damiani, D. E. 134 D’Amico. A. 89. 134 Dannetun, H. M. Datye, A. Davey, N. M. Degani, Y. Del Angel, G. A. Delcourt, M.-0. Demmin, R. A. Deronzicr, A. Demen, M. Desilvestro, J.

185; 186 135

2, 175 40, 133

189 187 135 39

I14 I34

Despic, A. R. Dettmcier, U. De Visser, A. Diaz Guerrero, G. Dickson, R. S. Dimaggio, C. L. Dimitruevic, S. M. Dimitrov, KH. Dimitrova, R. Diwell, A. F. Dobrovolszky, M. Dodgson, 1. L. Doi, Y. Dolphin, D. Dorbon, M. Douple, E. B. Duerst, R. W. Duh& F.

Egi, Y. Einstein, F. W. B. El-Boragy, M. Elissev, N. A. Ellner. M. Enomoto, T. Enos, R. Erdohelyi, A. Ernst, S. Esplugas, S. Etourneau, J. Evers, J.

Feller, H. G. Fendler, J. H. Fergusson, S. B. Ferrat, G. Ferrier, G. G. Figueras, F. Filipek, S. M. Filipovich, G. Findlay, R. D. Finocchiaro, R. S. Fogelberg, J. Fortunato, G. Fox, M. A. Franse, J. J. M. Frese, K. W. Friedrich, F. Fripiat, J. J. Froment, G. F. Frumar, M. Fuentes, S. Fujimoto, K. Fujinami, T. Fujishima, A. Fujitani, Y. Fukumoto, Y. Fukuzawa, S.-J. Furuya, N.

Galwey, A. K. Gandhi, H. S. Gamier, F.

Page 38 89 86 36

I54 131 88 41 41 50

135 162 43 38 41

118 186 36

39 38 37 40 37 90 26

136 40

187 37 37

36 89, 137

42 189 175 I89 36

186 190 131 I86 89 88 86

133 I34 89 41

37,38 189 189 137

133, 134 135 40

137 91

60 136 90

Page Gentry, S . 1. 41 Geoffroy, G. L. 137 Gershuni, S. 187 Getoff, N. 88 Gilbert, M. L. 91 Godakrishnan. 1. K. 36 Goiecki, T. Gorte, R. J. Gratzel, M. Gray, P. Grcer, A. L. Griffiths, J. F. Griggs, C. G. Grisnik, S. P. Grossmann, H. Grove, D. E. Griinling, H. W. Gsellmann, 1. Gualnal, G. Gutierrez, C.

Hagenmuller, P. Hakuta, T. Haller, G. L. Hamada, H. Hanabusa, K. Haradome, M. Haraya, K. Harrison, B. Hasan, A. Hashimoto, K. Hasko, S. M. Hatton, K. S. Hawecker, J. Hayashi, Y. Heard, N. E. Hecker, W. C. Hegedus, L. S.

188 135

134, 187 60 37 60 39

167 190 98

187 190 42

187

37 40 90 90 43 38 40 50 40 87 60

189 88 40 91

41, 136 42

Heidingsfeldova, M. 190 Heiner, H. 40 Heller, A. 86 Henderson, M. A. 136 Hennig, H. 133 Henriques, R. T. 86 Herz, R. K. 135, 188 Heywood, A. E. 113 Hilaire, L. 36 Hirabaru, 0. 43 Hiramoto, M. 39 Hirjak, M. 37 Hodeau, J. L. 37 Hojo, N. 43 Hollis, L. S. 87 Honda, K. 133, 134 Horcic, K. 38 Hous, N. 189 Hrushesky, W. J. M. 138 Huang, C. 91 Huang, C.-B. 88 Huck, M. 190 Hung, L. S. 185 Hunt, L. B. 30, 112,

130, 180


Hurd, T. J. Hwang, C.-H.

Ido, T. lijima, H. Ikariya, T. Imanaka, T. Inokuma, T. Inoue, A. Inoue, M. Inui, T. Isagulyants, G. V. Ise, T. Ishii, Y. Ishizuka, Y. lto, N. Ito, T. Iwahara, H. Iwasawa, Y. lyer, R. M.

JakSii., M. James, B. R. Januszkiewicz, K. Jegorov, A. Jellinek, H. H. G. Jerome, D. Joh, T. Johnson, B. F. G. Johnson, D. C. Johnson, W. C. Johnston, G. R. Jolly, P. W. Jones, R. A.

Kachi, H. Kaeriyama, K. Kakuta. N.

Page 56

186

42 90

186 136 38 87 42

42,89 40 90

186 88 40 90 91

189 36

88 38

137 42 38 86

136 154 132 185

17, 185 186 132

38 189 88

Kaldor,' A. 90 Kalvanasundaram. K. 187 Kaminsky, M. Kamiya, M. Kaneda, K. Kaneko, M. Karge, H. G. Kato, H. Kavan, L. Kawakami, K. Kawamura, K. Kawano, H. Kawashima, A. Kawashima, Y. Keen, R. Keghouche, N. Kimura, S. King, F. King, K. A. Kintaichi, Y. Kita, H. Kitamura, T. Kleykamp, H. Klvana, D. Knitton, J. F. Knox, G. R. KO, C. S. Kobayashi, M.

137 137 136

88, 133 40 89

134 40

186 186 87 40 81

187 86

146 131 90

39,135 136 131

16 63

130 135 136

Page Kobayashi. T. 137 Menovsky, A. Kochubey, D. 1. 186 Meyer,H. Kojima, M. 189 Meyerstein, D. Kolb, D. M. 39 Mills, A. Kolotvrkin, YA. M. 87 Minami. 1. Kordisch, K. Koritala, S. Kotz, R. Koudelka, L Kozlowski, E. Krill, G. Krishnan, C. V. Krstajii., N. Kriiger, M. M. Kui. H. W. Kummer, J. T. Kutal, C. Kuvinova, 1.1. Kuwahara, Y.

Lamy, C. Lawrence, C. Leach, S. Lee, K. C. Ligare, P. Lcger, G. Leger, J. M. Lehn, J.-M. Leung, T. W. Leupold. E. 1. Lietz, G. Likholobov, V. A. Lin. M. C.

190 190

39, 132 37,38

188 36

134 88 36 37

190 39 87 90

132 26

133 38 36

114 132 88 38 89

135 186 188

I~

Mmbu, H. Miraglia, S. Mishmash, H. E. Misono, M. Miura, N. Miyake, H. Miyake, T. Miyama, H. Mizomoto, M. Moiseev, 1. 1. Molle, W. Morita, H. Moro-Oka, Y. Moser. J. Motoo, S. Moutet, J.-C. Mukaitla, M. Murahashi, S . 4 Muraki, H.

Nagumanov, D. N. Nakabayashi, S. Nakao, Y. Nakase, T. Nakato, Y. Naota, T. Nash, A. Nash. P.

Lundstrom, 1. 185, 186 Nayak, S. D.

Page 86 31

187 26 42 42 37

186 90 89 43 42 88

189 186 86

135 138 134 91 39 87

137 135

38 133 189 43 39

137 86 86

136 Nayeb-Hashemi, A. A. 185

McCabe, A. R. McCabe, R. W. McGill, 1. R. McHatton, R. C. McKee, R. C. McKervey, M. A. McKinney, R. J. Macho, V. Madix, R. J. Mague, J. T. Mahadevan, V. Mahajan, D. Mahapatra, A. K. Maire, G. Manda, K. Mandler, D. Mann, K. R. Marezio, M. Marko, L. Masai, M. Maslova, L. K. Masumoto, H. Masumoto, T. Masumoto, Y. Matsuda, S. Matsumoto, K. Matsuura, S.A. Mau, A. W.-H. Mayer, J. W. Meinhaldt, A. D. Melancon, K.

89 131 62 88 43

137 90 42

13 1 87

136 190 42 36 40 40

186 37

135 135 40 36 87 87

189 132 135 88

37,185 185 186

Nestler, K. G. Newmark, R. A. Nijs, H. Nile, T. A. Nishiyama, S. Nobel, F. 1. Nome, F. Norimatsu, K. Nosaka, Y. Noufi, R. N. Nowobilski, P. Nueilati, M. Nugent, W. A.

Oehlinger, G. Oei, D.-G. Oh, S. H. Ohokoshi, S. Ohta, T. Okano, M. Okazumi, F. Okuhara, T. Okumura, T. Olszyna, A. On, H. R. Oyama, N. Ozawa, Y.

Pail, 2. Palensky, F. J. Palstra, T. T. M.

41 186 89 91

135 188

89,137 88 88

133 188 41 90

37 190 188 41 42

134 89 90

190 89 37 88 89

135 186 86

Panfilova, M. A. Paschoal, J. 0. Paul, R. L. Pavese, F. Pejsa, R. Pelizzetti, E. Perry, J. Pertici, P. Peters, A. Peterson, J. R. Petersson, L.-G. Peuckert, M. Phillips, J. Philpott, J. E. Pilloni, G. Pitts, T. G. Pjescid, M. Polievka, M. Poll, H. Polyakova, V. P. Popova, Z. Porter, J. D. Pouget, J. P. Predel, B. Prentice, G. Pretorius, R. Price, W. H.

Page 40

131 36 43

131 187 136 137 41

187 185, 186

132 138 12 39 91 38 42 89

112 41 86 86 37 91 37

190

Rabani, J. 187 Radjabov, T. D. 36 Raevskayi, M. V. 86 Rafaeloff, R. 89, 137 Rahmel, A. 62 RGeshwar, K. 133 Ramirez De La Piscina, P.

189 Ramstad, T. 132 Rard, J. A. 117 Raspolli, A. M. 42 Raub, C. J. 61, 134, 155 h h a k , B. Rehorex, D. Reid, F. H. Remeika, J. P. Renner, H. Resasco, D. E. Richards, P. G. Rieke, P. C. Rodionov, V. 1. Rombough, C. T. Ros, R. Roulet, R. Royer, G. P. Rudakov, E. S. Rudakova, R. 1. Russell, D. N.

Saburi, M. Saha, N. C. Saima, H. Saito, T. Sakai, S. Sakakura, T. Salvador, P. Sam, K.4. Sato, H.

37.38 133 61 37 37 90 17

187 86 91

132 132 189 38 38

137

186 89

189 90

137 137 187 90

189


Sato, T. Savitskii, E. M. Sayyed, G. H. A. Sbrana, G. Scarbrough, J. D. Schaudt, G. Schierson, D. Schmidt, H.-J. Schneider, K. Schorr, M. Schutz, J. Schwank, J. Schwarz, K. Searles, R. A. Seiyama, T. Sekizawa, H. Sell, J. A. Selwyn, G. S. Semina, 0. 1. Sermon, P. A. Seropegin, YU. D. Serpone, N. Seweryniak, M. Seymour, R. 1. Sharma, K. R. Sharudo, A. V. Shchainberg, K.-G. Sheldrick, G. M. Shenvood, P. M. A. Shida, J. Shimazu, K. Shimizu, 1. Shindo, Y. Shidoh, H. Shinovskis, E. J. Shinriki, N. Shirai, H. Shroff. A. Shutt, E Siedle, A. R. Simarro, R. Singleton, E. Skinner, P. E. Skundin, A. M. Slama-Schwok, A. SUukiC1, M.

Page 41 112 41 42 1 1 190 39 89 187 62 89 135 86 163 89 186 188 188 38 115 86 187 188 2 87 36 41 87 133 42 135 42 40 135 135 41 43 190 146 186 187 138 113 133 187 38

Smith, D. J. M. 39, 137 Smith, G. D. W. 89

Sobczynska, D. 89 Smyrk, P. G. 73

Page Sobukawa, M. 135 Siiderberg, D. 185

Sokolovskaya, E. M. 86 Solymosi, F. 136 Somorjai, G. A. 131 Sovey, J. S. 167

Spellane, P. 1. 131 Srinivasan, M. 136 Stalke, D. 87 Stebbings, W. L. 186 Stein, S. J. 91 Sterligov, 0. D. 40 Stem, E W. 87 Stolyarov, I. P. 186 Stucki, S. 39, 132 Sueiras, J. E. 189 Suna, A. 185 Sutin, N. 134, 190 Suzuki, H. 138 Suzuki, T. 137 Suzuki, Y. 86 Szafranski, A. W. 36

Soga, K. 43

Spasojevi6, M. 88

Takagi, Y. Takahashi, T. Takegami, Y. Takemoto, K. Taketa, Y. Takeuchi, R. Taki, H. Takoudis, C. G. Tamura, H. Tanaka, M. Tanaka, S. Tani, K. Tatlock, G. J. Tatsuno, Y. Tauszik, G. R. Taylor, J. R. 74, Teranishi, S. Theolier, A. Thomas, D. Thompson, D. T. Thomson, A. I. Thornton, J. A. Thummler, F. Timofeeva, G. 1. Ti Tien, H.

186 41 42 43 38 42 137 188

90, 131 137 91 90 56 90 188

117,131 136 90 186

26, 114 146 57 131 186 39

SUBJECT INDEX a=abstract page Absorption, solar on cermet coatings 57 Acetaldehyde, adsorption and reactions on Pt, a 131 Acetic Acid, production from syngas,

by Ru melt catalysis 63

Acetone, hydrogenation over Pt/TiO,, a 41 Acetylene, photosensitised cleavage to CH,, a 133 Acid Rain, pollution control 50

90 Adsorption, acetaldehyde on Pt(S) surfaces, a 131

heats of, for H,, CO, on SMSI Pd/TiO,, a 86 H, on Pd-SO,-Si, a 186

over Rhhppor t , a 89

Acrylates, dimerisation by Pd and Rh catalysts, a

Tiwari, S. TombPcz, 1. Tominaga, H. Tonnerre, J.-C. Torbicz, W. Toren, P. E. Tourillon, G. Touzani, A. Trevor, D. J. Triaca, W. E. Tricot, Y.-M. Trobs, U. Tsong, T. T. Tsubomura, H. Tsqji, J. Tsqji, Y. Tsuruya, S. Tu, K. N. Tundo, P. Tumbull, D. Twohig, M. F. Tysoe, W. T.

Uchida, H. Ugorets, M. Z. Uhlar, L. Uosaki, K.

' Updegraff, S. W.

Valentini, G. Van Damme, H. Vannice, A. Vannice, M. A. Vargaftik, M. N. Veile, P. Viney, M. M. Visca, M. Volter, J. Voronova, L. 1.

Wagner, F. J. Wakabayashi, K. Wakita, Y. Walsh, P. T. Walz, D. Warren, H. D. Watanabe, K. Watanabe, Y. Watts, R. J. Webber, S. E. Weitkamp, J.

Page 190 136 I89 190 89 186 90 16 90 87

89, 137 37 185 39 42 42 135 190 137 37 137 131

91 38 42 39 40

42 89 86 137 186 36 138 187 135 112

190 90 189 41

61, 134 91 36 42 131 88 40

Wells, P. B. Wen-Zhao, L. Whalen, M. V. Whetton, R. L. White, C. White, J. M. Whittlesey, B. R. Williamson, W. B. Willis, A. C. Willner, 1. Woell, 1. B. Wolf, E. E. Wood, E. P. Woollins, J. D. Worley, S. D. Wrzyszcz, J. Wyatt, M. Wu, N. L. Wu, W. T.

Page 162,168

185 167 90 130 88 132 136 38

40, 133 42 89 60 132 136 188 50 138 62

Xiu-Ying, G. 185

Yakhmi, Y. V. Yakovlev, 1. P. Yakovleva, A. A. Yamada, A. Yamamoto, Y. Yamashita, H. Yamazoe, N. Yano, N. Yaroshenko, A. P. Yasunaga, T. Yokota, A. Yokota, K. Yoneyama, H. Yoon, K. J. Yoshikawa, S. Yoshitome, H.

36 40 87

88, 133 138 189 89 87 38 189 43 135 131 137 186 40

Zagorodnikov, Zaikovsky, V. 1. Zamaraev, K. 1. Zamashchikov, V. V. Zecchin, S. Zejnilovic, R. Zemel, J. N. Zhmurko, G. P. Ziessel, R. Zingu, E. C. Zotti, G. Zu-Pei, H.

TO VOLUME 29

Alcohols, allyl, oxidation, a benzyl, electrooxidation, a isopropanol, from acetone hydrogenation, a oxidation by RuCI,(PPh,), + t-BuOOH, a primary, synthesis from syngas on Ru

production from syngas, by Ru melt catalysis propan-2-01, photocatalytic dehydrogenation

by Rh complexes, a secondary, oxidation to ketones, a

tertiary production from aryliodides and alkylaluminiums by Pd complexes, a

alloy/support, a

186 186 186 38 39 38 134 86 88 37 39 185

Page 87 88 41 42

42 63

39 138

189

Plarinum Merals Rev., 1985, 29, (4) 198

Alkanes, n-butane, isomerisation, hydrogenation hydrogenolysis on novel Rh/TiO,, Ir/TiO,, a

n-decane, dehydrogenation over Pt/AI,O,, a ethane, hydrogenolysis on Rh-TiO,, a n-hexane, isomerisation over Pt/zeolite, a

transformations, a methane, effect on Pd +Tho, gas sensing

photoproduction from C,H,, a production via CO, electrolysis, a synthesis from syngas over Rh/TiO,,

elements. a

Rh-Pt/TiO,, a propane, conversion to aromatics, a

-decenes, formed during n-decane de-

ethene, hydrogenation by novel Rh-TiO,

hydrogenation by Pd(I1) polymer complexes, a propene, hydroformylation, a

carbonylation by Pd melt catalysis hydrogenation by Pd(I1) polymer complexes, a

selective, by cationic Ru(I1) complexes. a Amines, primary-secondary transformation, a Ammonia, oxidation on Pt, a

photoproduction from azide ions, a synthesis, over Ru compledy -Al 0 catalyst, a

Arsenic, electrooxidation on Pt rotatin; d s c

Azides, photoconversion to NH,, a

Alkenes, carbonylation by Pd melt catalysis

hydrogenation, a

attached catalyst, a

Alkylation, benzene, by Rh(II)trifluoroacetate, a Akynes, I-, hydrosilylation by Ir complexes, u

electrode, a

Benzene, alkylation by Rh(II)triRuoroacetate, a

Benelius, history Book Reviews, Dictionary of Organometallic

Communds

chemisorption on Pt clusters, a

Page

90 40

189 d l

135

41 133 133

136 90 63

40

189 136

42 137 91 63

136 138 42

188 88

189

132 88

137 90 81

130 154

Brine, industrial electrolysis 88,98 12

Bromine, photoproduction via Ir complexes, a 187 Brownrigg, William, first experiments on platinum 180 1,fButadiene Monoxide, reaction with CO,, a 137 Butane, ignition and burning over Pt wire, a 134

OGanometallic Chemistry of Rh and Ir

British Antarctic Survey, H, generators for

Cancer, antitumour drug, a 87 chemotherapy 28,118

circadian timing, a 138 conference 72

Pd powders in 175 thick film dielectrics, a 91

Carbon Oxides, CO, adsorption on Pt electrode, a 132 chemisorption 131, 168 heat of adsorption on SMSI Pd/TiO,, a 86 hydrogenation, a 42,89 ignition and burning over Pt wire, a 134 oxidation. cvcled. a 135

Capacitors, multilayer ceramic 2

poisoning oi ~t/support catalysts, a syngas, chemical production from

conversions to parattins, a direct synthesis of acetic acid, a reduction of NO over Rh/SiO,, a reactions on Pt/TiO,, a

+H,O, CH, formation, a

methanation on Rh/support, a reaction with butadiene monoxide, a reduction to formate, a

Carbonylation, alkyl borates-benzylic bromide

CO,, electrochemical reduction on Ru electrodes, a

to esters, a carboxylic acid esters by Ru carbonyl iodide, a catalysts

134 63

189 89 41

135 136

133 136 137 88

42 42 63

Carbonylation (contd.) Page

pyridine, a 136 137

Carboplatin 72,118 Carboxylic Acid, acetic acid, synthesis from

syngas 63,89 Catalysis, catalytic converters, properties, a 188

Eighth International Congress 28 fine chemical manufacture, symposium 162 heter0geneous.a 40,41,42,89,90, 140, 141, 142,

188, 189 homogeneous, a 42,43,90,91, 142, 143,189, 190 industrial nitrogen oxides pollution control 50 kinetic analysis of complex reactions, a 41 metal clusters in, a 41

Catalysts, automotive, European legislation 163

warmup predictions, a 188 water-gas shift reaction in exhaust gases, a 188

bifunctional, naphthenes’ conversion, a 40 comprehensive review of refining 29 EUROPT-I, Pt/SiO,, characterisation 168 metal clusters, a 41 three-way. deactivation by P, Zn contaminants, a 136 Iridium colloids. H, photoproduction, a 187

thermal decomposition of H,O, a 38 Iridium Complexes, hydrosilylation of

1,3-dienes, I-alkynes, a 91 IIr(C3-N1-bpyXbpy),lz+, photosensitiser

olefins by Rh carbonyl complex aminel

terminal acetylenes of organic halides, a

used, analysis, a 135

for bromide solutions, a 187 135 I d a -Al 0,, CO-0, cycling, a

Ir-Ru/Sb,, syngas conversion to 0-C, compoinds, a

Ir/TiO,, alkane isomerisation, dehydrogenation, hydrogenolysis, a

Palladium, automotive, a Pd chloride, alcohol oxidation, a

hydroxy ester production, a oxidation of terminal, internal

olefins, a formic acid oxidation, a in redox fuel cells, a polycrystalline, in H,-D, exchange, a Pd+ThO,, in gas sensing elements, a

Palladium Complexes, alcohol and ketone production by carbonylative coupling, a

organic halide with terminal acetylenes’ carbonylation, a

Pd acetylacetonate, soybean oil hydrogenation, a

a-alkylpalladium (11). olefin reactions, a PdCI,( q4-norbornadiene), isomerisatior

of quadricyclene, a PdCI,(NCPh), + Lewis acid, acrylate

dimerisation, a tetrakis(triphenylph0sphine)-Pd, CO,

butadiene monoxide reaction, a Pd tributylphosphine, olefin syntheses, a

Pd/AI,O,, buta-1,3diene hydrogenation, a Pd/AI,O,, cyclohexane dehydrogenation Pd/,r-Al,O,, CO oxidation, a Pd(lI)/polymer, hydrogenation, a colloidal PVexcbange resin, preparation, a Pd/polyethylenimindSiO, beads, preparation,

Pd/SiO,, and Y-zeolite, hybrid, syngas

Pd/SiO,, zeolites, CO hydrogenation, Pd/support, C-bond reactions on, a

Pd- X/support, hydrotreating hydrocarbons Pd/Ti, electrocatalytic properties, 0,

properties, a

conversions. a

formic acid oxidation, a

90

90 135 87 42

137 41

190 135 41

189

137

190 42

39

90

127 42

135 16

135 136 189

189

189 89

189 41

114

evolution, a 38 86 40

Pd/TiO,, heats of adsorption, in SMSI state, a Pd/LaY zeolite, naphthene reactions, a


Catalysts (contd.) Platinum, automotive, after 34,800 km, a

in cycled feedstream, a clusters, gas phase reactions, a H, photoproduction from H 0 a polycrystdine, for NH, oxidailon, a

in H,-D, exchange, a redox fuel cells, a thermal decomposition of H,O, a wire, fuel/air ignition and burning, a

restructuring

gauze, changes during HNO, manu-

F’tRh10 gauze, with R-Rh/Al,O, coating,

Platinum Alloys, platinum-rhodium, automotive, effect of P,Zn poisons, a

facture, a

for HCN synthesis, a Platinum Complexes, acridme yellow/EDTA/

(phenazine)PtCI,(C,H,), hydrosilation, a [poly(3-methylthiophene)-Ag-Ptl, for

proton electrochemical reduction, a Pt-SnCl,.ZH,O for amine transformation, a

Pt/AI,O,, for buta-I,3diene hydrogenation, a ndecane dehydrogenation, a engine warmup tests, a methylcyclohexane dehydrogenation,

naphtha reforming, a WAI,O , PvTiO,, poisoning, a Pt-(Pb)-(Sn)/Al,O,, transformations, a FVa-AI,O,, c(3 oxidation, a Wy-AI,O,, HI decomposition, a

water/gas shift reaction in engine exhaust, a PtRe/Al,O,, methylcyclohexane

dehydrogenation, S effects, a Pt-Rh/Al,O,, coatings on PtRhlO gauze,

for HCN synthesis, a Pt/CdS/Ndion, H, photoproduction, a Pt/C, hydroxylamine production, a Pt/porous PTFE, H,-D, reaction, a Pt colloidal/anion exchange resin, a PVSIO,, standard European catalyst Pt/Si0,-AI20,, naphthene reactions, a Wstyrcae-divinyl benzene copolymer, for

H,-D, exchange, a Wsupport, NH, oxidation, a Pt/Ti, 0, evolution, a Pt-TiO,, acetone hydrogenation, a

CO, H, chemisorption, a photocatalysis to produce NH,, a

RuOx/Pt/I10,, water photolysis, a PdCaY zeolite, naphthene reactions, a Pt/H-ZSM-5, propane conversion, a Pt/zedite+Pr, Nd, La, isomerisation, dis-

Wultrsstable Y zeolite, naphthene reactions, a n - p a r a n reactions, a

Pt/ZnO, electrical conductivity, a Platinum Metals, review of 1983 work, a Rhodium, automotive, in cycled feedstrearns, a

Rh hydride - TiO, attached, novel, preparation, properties, a

Rhodium Moya, Rh-Pt gauze, changes during

Rhodium Complexes, asymmetric hydrogenation

H, photoproduction, a hydrosilylation crossliking of silicone

[(C,H,),RhC112, + Lewis acid, acrylate

RhCI,, H, photoproduction, a Rh(CO)CI(PPh,),, propene hydro-

K,PtCI, for H, photoevolution, a

S effects, a

p1/Ce/AI,O,, pt/Rh/Al,Op RWCe/Al,O, ,

proportionation, a

HNO, manufacture, a

of a-dicarbonyls, a

rubber, a

dimerisation, a

formylation, a

Page 135 135 90

187 188 135 190 38

134 60

136

89

188

39 186

90 42

135 40

I88

40 41

134 135 135 40

188

40

188 88

188 189 189 168 40

41 188 38 41

135 88

187 40 89

41 40 41

185 135 135

189

89

90 39

190

90 39

42

Catalysts (contd.) Page Rh,(CO) -ethylenediamine, a 136 1.5-hexaiene Rh chloride. a 42 Rh( 1)polypyridine complex, water gas shift

reaction,b RWAI 0,. buta-1,3-diene hydrogenation, a R d A I , O , , Rh/Pt/Ce/Al,O,, water gas shift

reaction in engine exhaust, a RWn-Al,O,, CO oxidation, a Rh,(COj,JtpAI,U,, water gas shift reaction, a ~Rh(CO),Cll,/~-~l,O,, zeolites, water gas shift

Rh/colloidal CdS, charge separation, H,

Rh,(CO),ddiaminated PS, a Rh carbonyl clusters resin beads, a,/-unsaturated

carbonyls, nitriles, hydrogenation, a colloidal Rh/H-form resin, preparation, a RWSiO,, NO reduction, a 41 RWsupport, C-bond reactions on, a

reaction, a

generation, a H, photoproduction, a

CO, methanation, a direct conversion of syngas to 0-C,

compounds, a formic acid decomposition, a

RWTiO,, alkane isomerisation, dehydrogenation, hydrogenolysis, a

CH; formation, a Rh-Pt/TiO,, CH, formation, a Ruthenium, melt for organic compounds

production RuO,.xH,O, for 0, evolution

Ruthenium Complexes, photocatalysis, in

[Ru(bpy),I’+, IRuL,(H,O)lz+, C,H, cleavage to CH,, a

Ru(bpy):+, photoreduction of dialkyl-4,4’-bipyridnium salts, a

Ru(bipy),CI,, formate production, a tris(2,2, bipyridyl-4,41-dicarboxylate)Ru(II)

smectites, a

dichloride sensitiser for light conversions, a

RuCI,(PPhJ,, oxidations of alcohols, a oxidations of secondary amines, a

Ru trichloride hydrate, oxidation of alcohols

Ru,CI,(BINAP),(NEt,), asymmetric

Ru carbonyl iodide, carbonylation,

to ketones, a

hydrogenations, a

homologation, a Ru(II)trifluoroacetate, benzene alkylation, a Ru(4,7-(CH,),phen).:+, photoreduction, a [RuL,(H,O)~~+, C,H, cleavage to CH,, a [RuHL,lPF,, selective hydrogenation of

alkynes, a RdAI,O , buta- 1,3-diene hydrogenation, a K.P+R$AI,O,. Fischer-Trousch. a R&w-AI,O,~ CO oxidation, a Ru comdedv -AI.O,. webaration. NH,

, > synthksis, a ” ’ ’

alcohols, a Ru-Mo-La/Al,O,, CO hydrogenation to

RuO,/CdS+RuO,/TiO,, H, photoproduction from H,S, a

characterisation, a Fe-Ru crystanites/amorphous C, preparation,

[Ru(bpy):+I/Nafio~~ap~te electrode, a Rdpoly- I-vinylnaphthalene, structure,

RdPS, structure, reactivity, a coUoidal Ru/H-form resin, preparation, a [Ru(bpy),12+/resin, photoreactions, a Ir-Ru/SiO,, syngas conversion to 0-C,

reactivity, a

compounds, a

(PPh,C,H,-SIL), water gas shift reaction, a Ru(CO),(PPh,C,H,-SIL), H,Ru+(CO),

190 135

188 135 90

90

89 137 136

136 189

. 136 189 136

89 136

90 136 136

63 26

89

133

40 88

134 42

137

138

186

42 137 134 133

138 135 90

135

189

42

187

137 88

137 137 189 134

90

43


Catalysts (conrd.) Page Rdsupport, Fischer-Tropsch reactions 146 Ru-Mo-Ndsupport, CO hydrogenation to

alcohols, a 42 RuOx/PfliO,, water photolysis, a 187

Catechols, oxidation by RuCI,PPh,),+t-BuOOH, a 42 Cells, chlorate, a 88

diaphragm, membrane, mercury, for CI, production 98 photoelectrochemical, Au/GaPc-CI/Ferri,

Ferrocyanide/GaPc-CI/Pt, u 187 Pt/n+/p-Si, Pt electrodes, HI, for solar energy

conversion, a 39 Cermets, platinum-alumina, stable coatings 57 Chatt, Joseph, reminiscences, history 126 Chemicals, fine, manufacture, symposium 162 Chemisorption, CO, H,, 0, on EUROPT-1 168

CO,H, on Pt/TiO,, a 135 hydrocarbons on Pt clusters, a 90

Chlordkd, industry 98 Chlorine, evolution, new Ru-Ti-Pd-Sn anode

coatings for, a 88 production, industrial 98

Chromatography, gas, by Pt/syrene-divinyl benzene copolymer, a 41

Cisplatin, chemotherapy, circadian timing, a 138 Coal, in Fischer-Tropsch syntheses 146 Coatings, Pt-AI,O, cermet, optical, selective absorber 57

Pt aluminide, gas turbines, u 187 hot corrosion environments 62

Pt-modified aluminide, in gas turbine blades 17 Pt-Rh/Al,O,, thin fdms on Pt-RhlO gauzes for

HCN synthesis, a 188 Pt/Ru, cathodes in chloroalkali production 98 RuO,/TiO,+PdSn,, on anodes for CI, evolution, a 88

Conference, Cancer Chemotherapy 72 Catalysis in Fine Chemical Manufacture 162 Eighth International Congress on Catalysis 28 Fuel Cells 107 Hydrogen in Metals 1 I5 Third International Chlorine Symposium 98

132 behaviour of Pt electroplated objects 155

17, 187 Pt aluminide coatings 62 steel in concrete 80

resistance, Pt-Ni superalloys 56

113 38

132 113 86 86

Cyclohexane, for storing H, 16

Dehydrogenations, over platinum metals 16,40, 90 Detectors, hydrogen 2, 89

i.r., a 43 methane, a 41 oxygen, high temperature, a 188

in steel furnaces 179 pressurised water reactor, a 91 pyroelectric gas, a 134

Deuteration, buta- 1,3-diene over platinum metals AW, , a 135

Deuterium, H,-D, exchange, a 41,135, 189 86

w-Dicarbonyls, asymmetric hydrogenation, a 90 Dielectrics, thick film, Pt/Au, Pd/Au. a 91

Corrosion, anodic of Ru-Ir alloys, a

protection, gas turbine blades

Ru in H,SO,, a 39 Crucibles, ZGS platinum for compound oxide growth Crystals, single, Bi,Ru,O,, electrical conductivity, a

electrodes of Ir, Pt, Rh, a growth, using ZGS Pt crucibles structure in Pd-Ni system, a UPt,, superconductivity and properties, a

isotope separation by Pd alloy membrane, a

Dlenes, hydrosilylation. a 91 Diesel Fuel, production from coal by Fischer-Tropsch 146 Diffusion. hvdrogen. ourhication 12 . I . . Dimedsation, acrylates, by Pd, Rh complexes, a 90 Diols, oxidative carbonylation, a 42 DNA, bound to bis(phenanthro1ine)

dichlororuthenium(II), a 87

Page

(Bi, Pb),PdO,, a I86 (perylene),M(mnt),, M=Pd, Pt, Au, a 86 Pt/ZnO catalysts, a 185 Bi,Ru,O, single crystals, a 38

Electrical Contacts, a 40,190 Electrical Resistivity, Pt,Fe,Mn,., alloys, a 36 Electrochemistry, a 38,39,87,88, 132, 133 Electrochromic Displays 2 Electrodeposition, a 40,41,42, 134, 187, 188

Pd, pulsed current, a 40 Pd-Ni 40,61 Pd-Ag, electronic, electrical applications, a 187

155 Pt on p-InP, photoelectrochemical properties, a 13 1 Pt on refractory metals, a 40 Pt metals, alloys, on nonprecious metals, a 190

Electrodes, anodes, lr, Pt, Pt-lr, Pt-Rh, Rh, activity for S,Oi- formation, a 87

platinised refractory metals, a 40 Pt, polypyrrole coated, a 134 Pt/Ti, Pt/Nb for corrosion protection 80 RuO,/TiO,+PdSn, coatings for CI,

evolution, a 88 cathodes, Os, 0s-W coated, electron emission, a 190

Pt/GaPc-CI in photoelectrochemical cell, a 187 graphite with Nafion+Ru(trpyXbpyXOH,)’+, a 88

with Nafion+lRu(bpy):+l, for

Pd, in pyroelectric gas analyser, a 134 photoanodes, RuO,/n-CdS, oxidation of

halide ions, u 133 39

Pt, CO adsorption on, a 132 Pt, fuel cells, a 43,91, 190 Pt, H, detectors, a 89 Pt, 0, probe in steel furnaces 179 Pt, preferred orientations, a 87

39 Pt, rotating disc, As(II1) oxldation, a 132 polycrystalline, sensitised, photoconversion, a 134 Ru, + Th, Pb, 0, reduction, a 88 Ru/C, Ru/teflon, CO, electrolysis, a 133

Electrical Conductivity, (Bi, Pb),PtO,,

RuGa,, a 37 RuO,, Bi,Ru,O, layers, a 37

Pt onto Cu, with intermediate layers

Pt/Ru, chloroalkali industry 98

photoconversion, a 88

photoelectrode, Pt/n+/p-Si, H, evolution, a

Pt, Rh(PPh,),, Rh(PPh ), generation, a

[Ru(bpy),L,12+/Pt photosensitive, a 39 RuC1,-coated GaAs, photoelectrodes, u 39 Tio,9,Ruo~~,0, crystal, photoelectrochemical

properues, a 187 single crystal, Ir, Pt, Rh, electrosorption of 0, a 132 surfaces, review, a 133

Electrolysis, brine 88,98 Electron Emission, a 190 Electronic Connectors 2 Electrodcs, compound oxides grown in ZGS Pt 113

Emission Control, European legislation 163 from industrial sources 50

Energy, solar conversion on Pt films/p-InP, a 86

Engines, catalytic converter properties during

devices, Pt metals in 2

Pt/n+/p-SiHI/Pt system, a 39 Pt-AI,O, cermet absorber coatings 57

warmup, a 188 exhaust gas conversions, a 188 lean-burn 163

Eaters, a 42 Etching, catalytic, Pt foils, C,H, oxidation, a 138 Ethylene, reactions over Pt metals, a 134, 138 Ethylene Glycol, via Ru melt catalysis 63

Fatty Acids, production via melt catalysis 63 Films, Pt/p-InP, solar energy conversion, a 86 Fischer-Tropsch, synthesis 41,90,146 Fonnate, photoproduction from CO,, a 88

Platinum Metals Rev., 1985, 29, (4) 20 1

Page

metals, a 41, 136, 189 36

Formic Acid, reactions over platinum

Friction, property of Pd alloys, a Fuel, H,, stored in cyclohexane

liquid, propane conversion to, u

methanol, gas diffusion electrode, Pt+Ru

phosphoric acid redox, using Pt, Pd as catalysts, a secondary, based on 0, reduction, a

Furnaces, steel, 0, detection in

Gas Turbines, blades, Pt aluminide coatings, a Pt-modified aluminide coatings

Gauze, PtRhlO, with Pt-Rh/Al,O, coating, HCN

Glass, industry, platinum in Glasses, metallic, Pd alloys, preparation, phase

Pd,,Ni,,P,,, preparation, a Pd-Si, H in, properties, a

Hexanes, chemisorption on Pt clusters, a n-,transformations over Pt, a

History, First experiments on Pt Friedrich Wohler Joseph Chatt, reminiscences Richard Knight & malleable platinum

Hydrocarbons, aromatic, propane conversion to, a hydrogenation over bimetallic Pd/support production from coal by Fischer-Tropsch

Fuel Cells, alkaline, electrodes in, a

electrocatalyst, (I

synthesis, a

diagrams, a

Hydrocracking, n-paraflins, a Hydroformylation, propene, a Hydrogen, adsorption at Pd-SO,-Si, a

chemisorption by EUROPT- 1 catalyst detectors diffusion membranes, technology evolution on Pd, Ru, Os, a heat of adsorution on SMSI PdRiO,, a

16 89

190

91 107 190 43

179

187 17

188 106

37 37

131

90 135 180 R1

126 30 89

114 146 41 42

186 168

2,89 12

133 86

H,-D, exchange reactions, a 41,135, 189 H,/CO reactions, a 28,41,42,63,89,90, 135, 189 H,-0, reaction, on Pd-MOS, a 185 ignition and burnhg over Pt wire, a 134 in electrolytic Pd precipitates, a 134 in metals, conferdnce 115 isotopes, separatm by Pd alloy membrane, a 86 NO reduction over Rh/SiO,, a 136 photoproduction, acidine

yeUow/EDTA/K,PtCl,, a 39 by Rh/coUoidal CdS, a 89,137 at RuC1,-coated electrodes, a 39 from Hfwith Pt coated electrodes, a 39

187 from HIS via RuO,/CdS, RuO,/TiO,, a propanr2-ol by Rhcomplexes, a 39 from water. active sites of Pt. Pd. Ru. Ni.

Sn/TiO,'suspensions, u Ir sols or Pt, a problems, a Ru(4,7-(CHJ2phen):+, a RuO /Pt/TiO,, a

plasma interaction with Pd surface, a oroduction from HI over Pth-Al.0,. a

from H,0?S2- with NaAon/CdS/Pt films

production from H,O, high temp&&re

solubility in Pd-Si metallic glasses, a storage in cyclohexane for fuel synthesis, using Pt-Rh/Al,O, coating on

Pt-Rh 10 gauze, a Hydrogenation, CO 28,41,42,63,89,90,

over Pt catalysts, a Pd catalysts 89, 114, 135, Rh catalysts, a 90, 135, Ru catalysts, a 135,

decomposition, a

135, 41.

136; 136, 138,

133 187 88

134 187 XX .. 36 40

38 131

16

188 189 188 190 189 186

Page Hydrogen Generator, industrial, methanoVwater,

Hydrogen iodide, H, production, u 39,40 Hydrogenolysis, over platinum metals, a 42,90, 134, 189 Hydrogen Sulphide, H, photoproduction, a 187 Hydroisomerisation, n-paraffins, a 41 Hydrosilylation, u 91, 190 Hydroxylamine, production from NO using Pt/C, a 188 Hydroxylation, aromatic, oxidation of C-Pd, a 42

with Pd-Ag membranes 12

Imines, production from secondary amines, a Inks, thick film, Pd powders in lproplatin iridium, cluster Ir,(CO),OI,-CO),~,-SO,), a

electrodes, a Iridium Alloys, corrosion, 0, evolution, a

Iridium- Aluminium-Thorium-Tungsten, in

Iridium-Platinum, electrodes, a nuclear generators

surface composition, S impurity, a Iridium Complexes, organometallic, book review

survey, a 11r(C3-N'-bpy)(bpy),lzt, photosensitiser, a fac-Ir(ppy),, photoreductants, a [Ptzlr,(CO),(PPh,)31, synthesis, properties, a

Iridium Silicides, TbIr,Si,, Tb,Ir,Si,, magnetic

Isomerisation, reactions, a 39, properties, a

137 175 118 132

87, 132 132

11 87

185 154 87

187 131 87

37 4 1, 89, 90

Johnson Matthey, production of EUROPT-1 catalyst 168

Ketones, t t , B-unsaturated ketones, hydrosilylation, a 9 1 production, a 137,138,189

Knight, Richard, history of malleable platinum 30

Lead, elimination from gasoline 27 Lewis Acid, promoter, of Pd, Rh complexes, a 90

perpendicular magnetic anisotropy in Pd/Co, a 185

Fe-Pt, additions effects, a 36

Medical, cancer chemotherapy 28,72, 118, 138 Methanation, CO, over Pd/zeolites, SiO,, a 89 Methane, effect on Pd+ThO, gas sensing elements, a 41

production, a 133, 136 Methylcyclohexane, dehydrogenation, S effects, a 40 Microelectronics, Pd powder for 175

Naphtha, reforming on Pt/AI,O,, u 41 Naphthenes, conversions over bifunctional catalysts, a 40 Nickel, alloy, high temperature oxidation by Pt, u 185 Nitrogen Oxide, hydroxylamine production, a 188

industrial emission control 50 NO, reduction over RWSiO,, a 41, 136

Nuclear Fuels, properties, a 131, 186

Olefins, reactions over platinum metals, a 42, 136, 137 syntheses, a 42,90

Organometallic Cornplexea, book reviews 130, 154 Organometallic Compounds, cancer chemotherapy 72

history 126 Osmium, coated cathodes, electron emissions, a 190

compound, OsSi,, semiconducting properties, a 37 microdeposits on Ti, electrocatalysis, a 133

Magnetism, Tb,Ir,Si,, Tblr,Si,, a 37

PdMnGe, PdMnSi, a 37

RhMnGe, RhMnSi, a 37

Osmium Alloys, Osmium-Platinum, properties 112 Osmium-Tungsten, coated cathodes, electron

emission from, a 190 Osmium Complexes, 0 s bipyridine, 0s phenanthroline,

electrochemiluminescence, a 133 Oxidation, alcohols, a 42,87,138

amines to imines by Ru(I1) complexes, a 137 NH,, a 188 C-Pd to C-OPd, u 42 co, a 135 C,H,, for Pt etching, a 138


Oxidation (contd.) formic acid by Pd catalysts, a Mg-Si-Ni alloy, high temperature, by Pt, a Pt in Pt-based alloys, a

Oxygen, chemisorption, by EUROPT-1 detectors, high temperature evolution from Pd, FY, Au coated Ti, a

Ru-H,SO,, a corroded Ru-Ir alloys, a

photoproduction via [Ru(bpy),12+/resin, a over hydrated RuO, from water, a

reaction with H, on Pd-MOS, a reduction on Ru+Th, Pb electrodes, a species, electrosorption, a

“Oxygone” H, diffusion units

Palladium. Pd-BN-SI,N,-SO,-Si FET for H, , - . detection, a

C-Pd bond, oxidation to C-OPd, a cluster, giant, with -570 Pd atoms, a coatings by pulsed current electrolysis, a compounds, (Bi, Pb),PdO,, electrical

at low temperatures, a

electrical switching contacts, a electrolytic precipitates, H effects in, a high-temperature 0, detector, a H,-0, reaction on Pd-MOS, a H, plasma interaction with Pd surface, a microdeposits on Nb, electrocatalysis, a mobility in Pd,Si, a Pd(I1) in H,SO, solutions, properties, a Pd/CO thin film layers, magnetism in, a Pd-SO,-Si, H, adsorption, a powders, production, in thick film inks precipitates from nuclear fuels, structure, a thin films on glass C and Ni, H, evolution, a

membranes, H isotopes separation, a Palladium-Magnesium, phase diagram, a Palladium-Maaganeae-Gmnanium,-Sillcon,

Palladium-Nickel, coatings, a

conductivity, a (perylene),Pd(mnt),, resistivity, transitions

Pd selenide in NaOH, electrochemistry, a Pd,U, Pd,Pu in nuclear fuels, a

Palladium Alloys, friction behaviour, a

magnetic properties, a

electroplating

Page 41

185 36

168 179. 188

38 39

132 134 26 88

185 88

132 12

89 42

186 40

186

86 38

186 190 134 188 185 36

133 37 38

185 186 175 131 133 36 86

185

37 40

40,61 phase diagram, a 86

190 37

PdNiZO, AuPd6Cu2, electrical contacts, a

Palladium-Nickel-Phosphorus, amorphous Pd4,,Ni40~4,,, metallic glasses, preparation, a

thermoelectric power;under H,, a metallic glass, H in, properties, a

Pd,,,Si ,,, amorphous, surface composition, a Palladfum-Sliver, electroplated, in electronic,

Palladium-Sliver, membrane, for H, diffusion Palladium-Sulphur, phases, thermodynamics, a

Palladium Complexes, q3-allyl palladium complexes,

Palladium Siiicides, effect of ion irradiation on

Pd,Si, mobilities of Pd and Si, a ParafUns, n-, hydroisomerisation, hydrocrackmg, a

synthesis by Fischer-Tropsch, a from syngas, a

Petroleum, lead free, European legislation Shell platformer

reforming, conference pH, control, with Pt electrodes, a

electrical applications, a

preparation, chemistry, a

phase formation, a

wire, a 87 Palladium-Nickel-SNcon, amorphous wire, a 87

thermoclectric power, under H,, a 36 Palladium-Sillcon. amorphous, electric resistance,

36 13 1 186

amorphous, electric resistance,

188 12

13 1

186

185 37 41 90

189 163 21 28

134

Page 185

metal-insulator, a 86 Phase Diagrams, binary, thermodynamics, computation 74

nuclear fuel precipitates, a 131 37

Pd-H-Si, metallic glasses, a 131 Pd-Mg, a 185 Pd-Ni. a 86

Phase Changes, in Pd-Si, Pt-Si, ion irradiation, a (perylene),Pd(mnt),, (perylene),Pt(mnt),,

Pd alloys, metallic glasses, a

Pd-S, a 131 Photocatalysis 26,39,40, 88.89, 133, 134, 137, 187 Platformins new Shell olant 27

I,

Platinum, cermet coatings 57 compound, benzoic acid blues, a 132

(Bi, Pb),PtO,, electrical conductivity, a 186 cis-diammineplatinum w-pyrrolidone violet. a 132 Pt(SO,F),, R(SO,)F,, H,“SO,F),I, a 38 (perylene),Pt(mnt),, resiiivity, transitions

at low temperatures, a 86 trans(amine)PtCI,(C,H,), preparation, a 186 trans-(phenazine)PtCI,(C,HJ,

preparation, a 186 UPt, crystals, superconductivity, a 86

crucibles, ZGS 113 drugs, anticancer 28,72,87, 118, 138 effect on high temperature oxidation of

Ni-Si-Mg, a 185 electrodes 39,80,87, 132, 134, 179 electroplated on copper, with intermediate layers 155 films, solar energy conversion, a 86

foil, etching during C,H, oxidation, a 138 grain stabilised by 0.6% yttria, tests with

propellants 167 in fuel cell, a 91,190 in glass industry 106 in Pt/GaAs resistors, a 190 malleable, Knight’s contribution, history 30 plating by melt electrolysis, a 40 platinised pInP, deposition,

photoelectrochemical properties, a 131 Pt(S), acetaldehyde reactions on, a 131 thin film resistor, temperature measurement, a 139 wires, restructuring 60

leaching tests, a 36 Platinum-Boron-Yttrium, properties, a 86 Platinum-Cobalt, in thermometers, a 43 Platinum-Copper, phase diagram 74 Platinum-Gold-Rhodium, physical properties, a 86 Platinum-Iridium, -Rhodium, anodes, a 87 Platinum-Iridium, oxidation, a 36 Platinum-Iridium, -Rhodium, surface composition,

S impurity, a 185 Platinum-Iron, permanent magnets, effects of

additions on, a 36 Pt,Fe,Mn,. , electrical resistivity, a 36 Platinum-Njckel, superalloy 56 Platinum-Osmium, high temperature properties 112 Platinum-Palladium, oxidation, a 36 Platinum-Ruthenhun, oxdation, a 36 W~,Pt,,,. W,,F‘t,, as Schottky contact materials

m n-GaAs, a 190 Piatinum Complexes, [PtlIr,(CO),(PPhJ,l, synthesis,

first experiments on, history 180

Platinum Alloyr, Platinum-Aluminium, Platinum-Iron,

properties, a 87 cis-[FY(RNH,),(ascorbate)l, antitumour

actiiity, a - 87 tetrakis(diphosphito)Pt,, energy, electron

transfer processes, a- 187

blades 62,187 17

185

reactions, a 133

Platinum Alumiatde, coatings for gas turbine

Platinum Sllicides, effect of ion irradiation, a Platinum Metali Complexeq review of photocatalytic

modified, coatings in gas turbine engines

Platinum Metals Rew., 1985, 29, (4) 203

Page 134, 136

legislation 163

90 175 91

134 134 90

Poimning, of catalysts, a PoOution Control, automotive exhaust, European

Polymers, Pt-Ag organic conducting, catalyst, a

Prsssuriscd Water Reactor, Rh detectors, a P~OPMC, ignition and burning over Pt wires, a Propykne, ignition and burning over Pt wires, a Protic Acid, promotor of Pd, Rh complexes, a

industrial nitrogen oxides emissions 50

Powders, Pd, production for microelectronic use

Quedricyclme, isomerisation, a 39

Radioactivity, encapsulated power sources 11 Reduction, reactions, a 90,136 Refining, catalyst survey 29 Resistance, electrical, Pd-Si, Pd-Ni-Si, under H,, a 36 RedStnnCC Thmnomcters, Pt sheathed, Rh-Fe 11

Rh-Fe, characteristics 32-273.15K. a 138 Reristojets, space station auxiliary propulsion 167 Resistors, GaAs/Pt, a 190

139 RuO,, Bi,Ru,O,, thick fdm 2

thick film, a 38

photocatalysis, a 89 electrode surfaces, a 133 Ir, Rh, Co survey for 1983, a 87 naphthenes, alkanes on bifunctional catalysts, a 40 organometallic chemistry of Rh and Ir, a 154 Pd(I1) complex catalysis, with monoolefms, a 42 photocatalytic reactions of co-ordination

compounds, a 133 reaction data for organic catalysis, a 41 refining catalysis 29 Ru, Ru inorganic compounds, chemistry

and thermodynamics 117 single crystal electrodes, electrosorption of 0, a 132

135

voltammetric behaviour, a 39 186

electrical switching contacts, a 190 electrodes, electrocatalytic activity, a 87,132

microdeposits on Au, electrocatalysis, a 133 precipitates from nuclear fuels, structure, a 131 Rh(II1) with K, CO chemisorption on, a 131

Rhodium AUoys. Rhodium-Copper, phase diagrams 74 Rhodium-Gold-Platinum, physical properties, a 86 (Sn,. Er,)Er,Rh,Sn,,, superconductivity, a 37 ~ h ~ d i t ~ ~ ~ - ~ . a g . a c w - ~ n ~ n , nopiurn-

MangmercSillcon, magnac propmbes, a 37 Rhodium-Platinum, electrodes, activity, a 87

185 Rhodium Complexeq organometallics, book review 154

organic, survey, a 87 Rh,(CO),OI-f-Bu,As),~-t-BuAs), structure, a 132

Ruthcalum, chemistry and thermodynamics 117 compounds, RuAI,, RuGa,, semiconducting, a 37

Pt thin film, for temperature measurement, a

Revlew, co-ordination compounds in

transition metals in organic syntheses, a Rhodium, compounds, Rh(PPh,),, Rh(PPh,),,

Rh,U, Rh,Pu, in nuclear fuels, a

geology. a 37

surface composition, S impurity, a

Bi,Ru,O, single crystals, a 28 Bi,Ru,O,, electrical conductivity, a 37

corrosion in H,SO,, a 39 Ru,U, Ru,Pu, in nuclear fuels, a 186

electrodes, 39,88,98, 133, 134, 187 microdeposits on Ti, electrocatalysis, a 133 precipitates from nuclear fuels, structure, a 131

Ruthenium AUoyh corrosion, 0, evolution, a 132 Ruthenium- Alumlnhun, Ruthdum-Iron,

leaching tests, a 36 Ruthenium Complexci, bis (1.10-phenanthroline)

dichlororuthenium(I1) - DNA, a 87 Ru(bpy)’+.photoconversion,a 40,88,89,133,134,187

[RuCl,(bipy),l+ synthesis, a 87 IRu(bpyf,L,lz+, in electrode, a 39

Ruthenium Complexes (contd.) Page

BINAP),(NEt,), preparation, use, a 186 R~(trpyXbpy)(OH,)~*, activity, u 88

37 26 38 39

Ru,Ci,(BINAP),(NEt,), Ru,C14(p-tolyl-

[(RuX(bipy),fiol:O)l~*, synthesis, a 87 Ru(II1) porphynns, a 38

RuO, thick film resistors, a RuO,, formed from Ru corrosion, a Bi,Ru,O, 2.37

Ruthenium Oxides, RuO,, electrical conductivity, a RuO, hydrated, for 0, evolution, a

Schottky Barriers, Pt-W alloys on n-GaAs, a 190 43

Shell, new platformer plant 27 Silicone Rubber, crossliiking by Rh complex

catalysts, a 190 SMSI, in catalysis 28,86 Sodium Hydroxide, industrial production, a 98

Pd dispersed in, polarisation studies, a 38 Soybean Oil, hydrogenation by Pd acetylacetonate, a 190 Space, station, auxiliary propulsion jets 167

cratt, Ir alloys in power source 11 Steel, corrosion protection, in concrete 80

furnaces, 0, detector in 179 Sulphur, impurity in Pt-Ir, Pt-Rh alloy surfaces, a 185 Sulphuric Acid, Pd(I1) in, a 38 Su~erallovs. Pt-enriched Ni 56

Schottky Diodes, Pd,Si/p-Si, i.r. emission, a

Superconbuctivity. (Sn,.,Er,)Er,Rh,Sn,,. single crvstals. a 37

.UR, crystals, growth, properties, a Synthesis Gas, conversions over Ir-Ru/SiO,, a

conversions, over hybrid PdSiO, and Y-zeolite, a

86 90

189 by Ru melt catalysis 63 Ru-Mo-Nalsupport, Ru-Mo-La/Al,O,, a 42

direct conversion to acetic acid over Rh/support, a

NO reduction over Rh/SiO,, a reactions, conference

Tanaka, K. K., centenary Temperature Measurement

Thennoclectric Power, amorphous Pd-Si, Pd-Ni-Si, under H,, a

Thermometers. Pt-Co, low magnetoresistance, a Thick Fh. conductors

inks, Pd powders in Pt/Au. Pd/Au diclectrics, a resistors RuO, resistors, a sensors

P d C o layers, ma etism in, a Pd on glass C and%, electrocatalysis, a Pt, resistor, for temperature measurement, a

Tltanlum, anodes, reactions, a Toluene, disproportionation, over modified Pt

Turbines, gas, Pt aluminide coatings

Vinylethylme Carbonate, production, a Vitamin C, Pt complexes of, antitumour

resistance thermometers

Thin Film, electrical equipment

zeolites, a

activity, a

89 41 28

73 43,138 11,138

36 43

2 175 91

2 38

2 2

185 133 138

38,88

41 17,187

137

87

Water, heavy, determination, by H,-D, exchange, a 4 1 38

H,-D, exchange over Wporous PTFE, a 189 in photochemical splitting, a 88,133,134,187

43,90,136,188,190 180

11 87

180

high temperature, catalytic decomposition, a

Water G u Sbw Ructionq a Watson, wtfliun, flrst experiments on Pt, history

Wl rw Ni-Pd-Si, Ni-Pd-P, production, properties, a

Waod, William, first experiments on Pt, history

Welding, Ir alloys in nuclear power sources

WWer, Friedrich, history 81


Documents

Con tents · UK ISSN 0032-1400 PLATINUM METALS REVIEW A quarterly survey of research on the platinum metals and of developments in their application in industry VOL. 20 OCTOBER 1985