Sulfated zirconia[1]

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