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Structures
Proce
sses
Properties
Performance
Metals
CeramicsPolymers
Composites
ZrO2
synthesis
characterizationPoornaprajna institute
of scientific Research ,
Bangalore
Vijaykumar Marakatti
Sulfated Zirconia as a strong solid acid catalyst for selected organic
transformations
Outline of the talk
Introduction. Synthesis of zirconia supported catalyst. Characterization. Structure. Acidity and super acidic properties of SZ. Application of SZ catalyst for organic
transformations. Conclusions.
Introduction
Most of the industrially catalyzed process are based on acid catalyst.
Different types of acid catalysts 1. Heteropolyacids. 2.Amberlyst 3.Nafion-H 4.Clays and Zeolites. 5.Metal oxides. 6. Anion modified metal oxide.(1980) ex:Sulfated zirconia, tungated zirconia
Metal oxide – ZrO2,TiO2,SnO2,Al2O3 etc
Anion - MoO4-2 ,SO4
-2,WO4-2 .
Modification of metal oxide with anion generate new active acid sites.
Which are different then their individual acid sites.
Combination of different metal oxide with different anion gives a large no of catalyst with different distribution of acid sites.
Advantages of Anion Modified metal oxide
Active over wide range of Temperature. Resistant to thermal extrusion. Low reaction temperature. Easy preparation and low cost.
Disadvantages of Anion Modified metal oxide Sensitive to Reducing atmosphere. Forms acid if Water is present at high temperature
SynthesisSulfated zirconia
a. Sol-Gel
H2SO4
Zirconium n- Propoxide propanol
Drying 120 C
Calcination 650 C
b. Decomposition
Zr(SO4)2
SO4-2/ZrO2
Journal of catalysis 150, 18-33(1994)
C. Precipitation and impregnation method
ZrOCl2 NH4OH
PH - 8
Zr(OH)4
Zr(OH)4
120 C
H2SO4
SO4-2/ Zr(OH)4
650 C
SO4-2/ZrO2
Acidity of catalyst depends Activation temperature. Precursor zirconium sulufur sulfur content 1N,2N. PH
Synthesis
Chemical review 109, 2185-2206(2009)
SynthesisTungstated zirconia
a. Impregnation method( dry , wet ,incipient)Ammonium tungatate + H2O
ZrO2 or Zr(OH)4
80 C 2hr
Stir for 4 hr
110 C 6hr
Calcined at 600C
WOX/ZrO2
Evaporation
Co-precipitation Calcinations temperature. Preparation method.
Catalysis letters 131, 122-128(2009)
Characterization a. X-Ray Diffractometer
10 20 30 40 50 60 70
ZrO2
SZ 1N
SZ 1.5N
SZ 2N
WO3/ZrO
2
Inte
nsit
y(a
.u)
tt
Present Work
WOX/ZrO2
SZ-2N
SZ-1.5N
SZ-1N
ZrO2
b. FT-IR SpectraCharacterization
900 1000 1100 1200 1300 1400
995
1044
1138
1212% T
ran
sm
itan
ce
Wavenumber(cm-1)
SZ 2N
PRESENT WORK
C. TG-DTACharacterization
575 C
600 C
650 C
B.M Ready .etal Chemical review 109, 2185-2206(2009)
d. Textural properties
Characterization
material Surface area M2/g
Crystalline size(nm)
Sulfur / Wloading
ZrO2 42 11.2 --
SO4-2/ZrO2 100 7.3 2.3
WO3/ZrO2 35 11.9 6
Journal of molecular catalysis A. Chemical 109, 2185-2206(2009)
Structure
B.M Ready .etal Chemical review 109, 2185-2206(2009)
ACIDITY
material NH3 desorbed(Ml/gram)
ZrO2 5
SO4-2/ZrO2 16
WO3/ZrO2 9
(TPD)
ACIDITY(FTIR- Pyridine)
Catalyst B/L ratio
SO42/ZrO2(1N) 1.6
SO42/ZrO2(1.5 N) 1.03
SO42/ZrO2(2 N) 0.92
B/L Ratio : SZ 2N<SZ 1.5N< SZ1N.
Present work
1700 1650 1600 1550 1500 1450 1400
ZrO2
SZ-1N
SZ-1.5N
SZ-2N
LB+LB
Abs
orpt
ion
(a.u
))
wavenumber (cm-1)
Super acidity?
Bronstead & lewis acidity. Ho indicator method. Colour change. Different acid sites. TPD Decomposition of adsorbate molecule. adsorption on catalytically not active. CaO-NH3- at high T Skeletal isomerization at low T.
Commercial application in hydroisomerization process
n- Paraffins H2 iso-Paraffin
- Aromatics – high octane number and C/H ratio- Branched HC – High octane Number- Hydro cracking is competing reaction.- Low temperature.- Bi-functional catalyst.- Pt/Alumina /Cl-.- Pt / SiO2-Al2O3.
- Pt /Sulfated zirconia-HYSOPAR-100 ppm- WO3/ZrO2.
Applications in organic transformations
Selective hydrolysis of cellulose into glucose
Cellulose is the most abundant source of biomass. Enzyme catalyst – separation problems.
Reaction conditions: milled cellulose 45 mg, catalyst 50 mg, distilled water 5.0 mL, 24 h.
Prins Cyclization
O
H H
O
OH+
Condensation of olefin with aldehyde. C-C bond forming reaction.
Styrene Para formaldehyde 4-Phenyl 1,3-Dioxane
Industrially high boiling solvent. Plasticizer, curing agent , Pigment dispersant
Protecting group in organic synthesis. monomer and additives in polymer industry.U.S Patent -4,185 ,019 Jan.22(1980)
Catalyst Formaldehyde source Yield
Sulfuric acid Formaldehyde 75
Heteropolyacids Paraformaldehyde 99
Trifluromethane sulfonic acid Formaldehyde 92
MoO3/SiO2 paraformaldehyde 73
SO3H-SBA-15 Formaldehyde 100
Indium bromideIonic liquids
paraformaldehyde 91
Organic salt of heteropolyacids Formaldehyde 97
Zeolites paraformaldehyde 40
Sulfated zirconia paraformaldehyde 93
Literature survey
Reaction conditions; 20 mmol styrene, 60 mmol paraformaldehyde, solvent :dichloroethane =10ml ;Catalyst: SZ-2N. Temp =80°C. Reaction time: 6hr
Catalyst Time in hrs
ConversionWt%
Selectivity Wt%
TONmmol/gram
SO4-2/ZrO2 7 99.8 92 67.66
WO3/ZrO2
7 96 85 60.14
H-Beta(25) 7 22 88 14.14
H-ZSM-5(38) 7 1 30 o.22
H-Y(16) 7 1 50 o.36
H-Mordenite(16) 7 2 46 0.67
Cs2.5H0.5SiW12O40 1 97 68 49.33
Montomorlonite-K-10 2 100 67 49.36
Reaction conditions; 20 mmol styrene, 60 mmol paraformaldehyde, solvent :dichloroethane =10ml ;Catalyst : 7 wt % of reactant, Temp =80°C. Reaction time: 6hr
Screening of catalyst
Effect of solventsolvent Dielectric
constant
Acceptor
Number(A.N
)
Donor
Number
(D.N)
Yield for
4-Phenyl
1,3
dioxane
No solvent --- --- --- 56
Tri ethyl amine 2.4 0
Cyclohexane 2.6 47
Toluene 2.4 64
1,2dichloro
ethane
10.1 85
Nitrobenzene 34.8 22
Acetonitrile 36 0
Isopropyl
alcohol
18.3 33.8 21.1 0 Reaction condition: 10 mmol styrene; 30 mmol Paraformaldehyde; 10 wt% of catalyst (reactant); Temp =80°C; solvent =5ml; reaction time =7 hr. The acceptor number( Lewis acidic) is obtained from the 31PNMR chemical shift values related to that of the 1:1 adduct (C2H5)3PO-SbCl5 dissolved in 1,2 dichloroethane.The Donor number (Lewis base) defines the negative DH value for 1:1-adduct formation between sbCl5 and an electron pair donor solvent in diluted solution in non coordinating solvent 1, 2-dichloro ethane.
1.4 61
0 0
8.2 0
16.7 0
14.8 4.4
18.9 14.1
Catalyst Acidity B/L
ratio
Time in (hr) conversion Selectivity
Blank ---- 7hr 1.6 70
Zr(OH)4 --- 7hr 1.7 72
ZrO2 --- 7hr 2.3 74
SZ-1N 1.6 3hr 87.8 74.6
SZ-1.5N 1.04 3hr 76.3 78
SZ-2N 0.92 3hr 73 88
7hr 99.8 92
Sz-2Na --- 7hr -- --
Sz-2Nb -- 7hr -- --Reaction conditions; 20 mmol styrene, 60 mmol paraformaldehyde, solvent :dichloroethane =10ml ;Catalyst: SZ-2N. Temp =80°C. Reaction time: 6hr.a- Aqueous Formaldehyde instead of paraformaldehyde.b – Aqueous Formaldehyde instead of paraformaldehyde, reaction temperature = 100°C
Sulfated zirconia catalyst
60 80 10040
50
60
70
80
90
100
Reaction Temperature
conv
ersi
on o
f sty
rene
60
70
80
90
100
selectivity of dioxane
Optimization of reaction conditions.
a. Temperature
Reaction conditions; 20 mmol styrene, 60 mmol paraformaldehyde, solvent :dichloroethane =10ml ;Catalyst: SZ-2N. Temp =80°C. Reaction time: 7hr , catalyst weight -7 wt%.Reaction time -100C – 4hr
3 5 7 960
65
70
75
80
85
90
95
100
Perc
en
tag
e (
%)
catalyst (wt%)
conversion of styrene selectivity for 4 phenyl 1,3 dioxane
b. Catalyst weight
Reaction conditions; 20 mmol styrene, 60 mmol paraformaldehyde, solvent :dichloroethane =10ml ;Catalyst: SZ-2N. Temp =80°C. Reaction time: 7hr
1:1 1:2 1:3 1:40
20
40
60
80
100
Per
cen
tag
e(%
)
Styrene:Paraformaldehyde mole ratio
conversion of styrene selectivity for 4-Phenyl 1,3-dioxane selectivity for cinnamyl alcohol
C. Mole ratio of styrene :paraformaldehyde
Reaction conditions; solvent :dichloroethane =10ml ;Catalyst: SZ-2N. Temp =80°C. Reaction time: 7hr , catalyst weight -7 wt%.
Leaching test
0 1 2 3 4 5 6 7 8 9 100
10
20
30
40
50
60
70
80
90P
erc
en
tag
e(%
)
Time (hr)
conversion of styrene selectivity for 4-Phenyl1,3-dioxane
Reaction condition: 20 mmol styrene: 60 mmol Paraformaldehyde; 7 wt% of catalyst (reactant); Temp =80°C; solvent: Dichloro ethane =10ml.
Recycling test
Catalyst Yield
cycle 1 92
cycle 2 91.4
cycle 3 90
cycle 4 89.8
10 20 30 40 50 60 70
Cycle 4
Cycle 3
Cycle 2
Cycle 1
Inte
nsit
y (a
.u)
2 Theta
S
O
O
Mechanism of reaction
C
O
H H
H
OH
H
C
O
H
Zr
O
O
O
O
OH
O
O
CH2OH
O
O
OH
H
S L
B
ZrO2
conclusion Sulfated and tungstated zirconia catalyst were
synthesized by the precipitation and impregnation method.
Characterization of sulfated zirconia by various methods were discussed.
Prins reaction of styrene with Paraformaldehyde is carried out using Sulfated zirconia catalyst.
Optimization study , effect of solvent and comparison of other acid catalyst is done.
SZ-2N showed good activity and selectivity for the prins reaction.
Thank You