Title of Invention

A PROCESS FOR PREPARATION OF OPTIMIZED SURFACE SUPPORTED SULPHATED ZIRCONIUM SILICATE CATALYST

Abstract Surface Supported Sulphated Zirconium Silicate Catalyst prepared by the process characterized in that the said process comprises of i. preparing silica gel with pore volume of 0.9 ml/g and particle size of 2 to 5 mm by leaching of the surface with potassium hydroxide solution ii. dissolving calculated quantity of zirconium oxy chloride on the basis of weight of silica, in water, the volume of water being equivalent to the pore volume of silica taken in 1 (i) iii. loading dry silica gel with zirconium oxide expressed as zirconium oxy chloride with various loading levels from 1 to 4% from its aqueous solution as in 1 (ii) iv. soaking weighed quantity of silica in zirconium oxy chloride solution for 20 to40 minutes more particularly for 30 minutes v. precipitating the Loaded zirconium as zirconium hydroxide by exposing to ammonia vapors for 2 to 3 hours in a closed vessels vi. drying the filtered precipitate in an oven at 120°C for 12 hours vii. sulfating the dried product by using lN sulfuric acid viii. calcining at 450°C for 4 hours ix. washing the catalyst so obtained with water to remove traces of sulfuric acid and x. calcining again at 450°C for 2 hours and xi. cooling and crushing into powder of 40 mesh size, for experimental and industrial use xii. recycling the catalyst after reaction for further reactions as described in examples
Full Text FORM 2 THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
[See section 10; rule 13] -

"A PROCESS FOR PREPARATION OF OPTIMIZED SURFACE SUPPORTED SULPHATED ZIRCONIUM SILICATE CATALYST"
(a) MALSHE VINOD CHINTAMANI
(b) 1, Staff Quarters, UDCT Campus, Matunga Mumbai - 400 019. Maharashtra, India
(c) Indian National
The following specification describes the nature of this invention and the manner in which it is to be performed:
30-12-2004

TECHNICAL FIELD
This invention relates to a process for preparation of surface supported sulfated zirconium silicate catalyst. This invention further relates to optimization of surface supported sulphated zirconium silicate catalysts.
BACKGROUND AND PRIOR ART
Use of Sulphated Zirconia as a catalyst has been reported by Yadav and Nair in "Microporous and Mesoporous Materials (1999)33, 1-48. Sulphated Zirconia has been described as the most promising and emerging catalyst for the times to come. In that paper the zirconia or zirconium oxide catalyst was prepared with modified anion such as sulfate ions form highly acidic catalyst depending upon the method of treatment. The characterization and various parameters affecting catalyst preparation were also studied. These prepared catalysts were examined for their reactivity and reusability for various model reactions such as hydrocarbon isomerisation, alkylation, acylation, esterification, etherification, condensation, nitration, cyclisation, cracking, and various other reactions where acidic catalysts are used. The results obtained from these catalysts were compared with conventional catalyst and comparative conclusions were derived confirming the better activity of Sulfated Zirconia catalysts.
Until 1999 only Sulfated Zirconia was extensively studied. The concept of supported Sulfated Zirconia has emerged only in the new millennium. In the last three years, Sulfated Zirconia was supported on various supports which were not reported earlier. Various methods of preparations were reported since then. In one of the methods alumina promoted Sulfated Zirconia was supported on mesoporous molecular sieves of pure silica MCM-41 and SB A -15. The catalyst was prepared by direct impregnation of metal oxide
2,

onto the silica surface, followed by solid state dispersion and thermal decomposition. Chen et al, Catalysis Letters(2001),78(l-4),223-229 reported the supported Sulfated Zirconia by direct exchange of metal containing precursor for the surfactants in the synthesized MCM-41 material).Wang S., Guin J. A. (Microporous and Mesoporous Materials) (2001),50(2-3),(201-208) reported the preparation of supported Sulfated Zirconia catalyst by precipitation of with ammonia at pH 10 and further
calcination at 600°C. The reactivity was enhanced by 30 - 50 % compared with acid resin Amberlyst 15 in etherification reaction (Chemical Communication (2000),(24),2499-2500). Lei, T; Xu et.al. prepared catalyst supported on AI2O3 or
SiC>2 by impregnation method. This catalyst was used for isomerisation reaction of n -butane (Lei ,et al,*Applied Catalysis A(2000), 181-188 ). Huan, yin- yan et al. reported Silica or alumina supported Sulfated Zirconia prepared by dispersion followed by calcinations at 750°C (Haun, et al, Applied Catalysis (1998), 173, (1), 27-35). Another supported catalyst was modified by Grau, Javier Mario et al by the addition of Pt over various pure and heterogeneous supported Sulfated Zirconia like (i) pure (ii) Mechanically mixed with and (iii)
supported over AI2O3 or Si02 and comparative studies of their reactivity was done where it was seen that supported over
was the most stable and reactive catalyst (Grau et al, Applied Catalysis, A (1998),172(2),311-326). In another study the supported Sulfated Zirconia catalyst had been prepared by Anderson et. al (Can.J.Phy.Chem(1995),99(3),1444-1449)for the oxidation of SO2 or by impregnation with sulfuric acid and its surface properties and acidity have been characterized by IR spectroscopy. Another eco-friendly catalyst having sulfated metal oxide and mesoporous zeolites was prepared by Yadav, G. D. et al in GB 2332155(1999) who used it for producing oligomers from a-olefins, Fridel - Craft's alkylation and acylation reaction. In another by work by Yadav, G. D. et al. the reported in Green Chem (1999) Dec, (269-274) the catalyst was prepared by precipitating zirconia on calcined HMS and further treated with ammonia and was calcined at 550°C. This catalyst was used for alkylation of p-cresol with MTBE where major product was obtained with highest yield and conversion when compared to other conventional catalysts.
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The reactivity of this catalyst has been studied for isobutene alkylation by butane by Paukshtis, E. A. et al. as reported in Studies in surface science and catalysis 2002, 130c. It was seen that it has better catalytic activity and shape selectivity when compared to conventional acidic catalyst like AICI3 and BF3 .The performance of Pt catalyst supported on sulfated zirconia - silica with different stoichiometrics was investigated by Salmones, J. in n- pentane hydromerization reaction with enhancement in catalytic activity (Catal; Lett;(1996) 36, (135-138). In another study by Inada, K. et. al. in Chem. Lett;(l993), 10,(1795-1798) silica supported sulfated zirconia catalyst was used for reduction of aldehydes and ketones with 2- propanol, corresponding alcohols were obtained in high yields. In the catalyst silica supported sulfated zirconia the results obtained agreed with the models proposed by De Jong et al.in Surface Interface Anal (1992),(10),1795-1798) for sulfated zirconia catalyst on porous silica supports.
Sulfated Zirconia is known for high surface acidity. In spite of these products being known for about 20 years and their extensive capability to substitute homogeneous acid catalyst, no commercial product seems to have emerged. In a lecture delivered at UDCT in 1999 on Sulfated Zirconia catalyst, Dr. Francis Figueres commented that the problem of reproducibility in preparation of Sulfated Zirconia is so great that every time one made a catalyst, it was a new catalyst. This comment led us to the thinking and the development of surface sulfated zirconium silicate catalyst being reported here. Most of the synthesis starts from zirconium oxychloride precipitation as hydroxide followed by calcinations, sulfation with sulfuric acid or ammonium sulfate, then calcination to fix the acid sites and surface area. The attempt to fix surface area and acid sites simultaneously causes problem of variation in surface area, pore volume and pore size distribution, which is a well-known phenomenon in hydrous oxides. Secondly if a bulk of zirconium oxide is used up in preparing the massive matrix, it cannot contribute to the activity of the catalyst.
Wang et al in Chem. Commun. (2000), 2499-2500 have reported preparation of silica supported Sulfated Zirconia and studied the conversion of methanol and isobutylene to
4

MTBE. They have studied loading from 15 to 50 % and found a loading of 50% to give best performance. The authors have not considered the atom efficiency of the catalyst. (Zirconium is not a noble metal; it is still expensive" compared to elementary acidic materials like silica and alumina). Silica supported surfaced zirconia catalyst has following advantages.
1. It is possible to tailor physical properties such as surface area, pore volume, bulk density and particle size conveniently.
2. It is resistant to acids such as sulfuric acid, which ar£ involved in next step of preparation.
3. It forms covalent bond with group IV elements such as Ti, Zr, and Hf, hydroxides through the surface silanol groups that might be helpful in retaining the catalytic activity.
4. It is the most abundant element and is very inexpensive, has no disposal or toxicity problem.
5. In pure state, it is colorless.
Not many other industrial supports such as activated carbon, activated alumina or activated clay could offer these benefits.
SUMMARY OF INVENTION
A process for preparation of recyclable Optimized Surface Supported Sulphated Zirconium Silicate Catalyst wherein, the said process comprises:
i) preparing silica gel with^pore volume of 0.9 ml/g and
particle size of 2 to 5 mm by leaching of the surface with
potassium hydroxide solution; ii) drying the silica gel; iii) dissolving zirconium oxide as zirconium oxy chloride content
1 to 4 % on the basis of weight of silica in the water; iv) soaking the dry silica gel in the said zirconium oxychloride
aqueous solution for 20 to 30 minutes, more particularly for
5

30 minutes, to load / deposit the said zirconium oxy chloride
on dry silica gel; v) precipitating said loaded / deposited zirconium oxy cMoride
as zirconium hydroxide on silica gel by exposing to ammonia
vapors for 2 to 3 hours in closed vessels; vi) drying the said filtered precipitated zirconium hydroxide on
silica gel in an oven at 120°C for 12 hours; vii) sulfating the said dried the zirconium hydroxide on silica gel
by using IN sulfuric acid to sulfated zirconium on silica gel; viii) calcining the said sulfated zirconium at 450°C for 4 hours to
obtain sulfated zirconium silicate; ix) washing the said calcined sulfated zirconium silicate with
water to remove traces of sulfuric acid and x) calcining again the said washed sulfated zirconium silicate at
650°C for 2 hours; and
xi) cooling and crushing into powder of 40 mesh size for experimental and industrial use.
The surface supported sulfated zirconium silicate is a catalyst for an esterification reaction. The surface supported sulfated silicate catalyst used in one batch is used as a catalyst in the next batch of the said reaction without further treatment.
DETAILED DESCRIPTION
The process for preparation of surface supported sulphated zirconium silicate catalyst is disclosed in this invention. Optimization of the catalyst^ also disclosed.
Optimization of the catalyst
In most of the reported studies the loading of the sulfated zirconia on silica is in the higher range of 25-50 %. This high loading level could be advantageous in getting higher rate in simple ammoxidation, esterification, etherification, oxidation etc. In these cases the reaction proceeds in the surface layer as well as in the interiors i.e. bulk phase, of the solid acid catalysts. But as far as other reactions being carried out at higher temperatures,

it is observed that the reactions catalyzed by solid acids proceed mainly on the surface, at least in the surface layers.
Example 1
Esterification of butanol
1:1 mole ratio of butanol to acetic acid was taken in a three-neck flask fitted with a thermometer pocket with thermometer, a Dean-stark apparatus filled with butanol, a water condenser. The amount of catalyst with 1% zirconia was 5% by weight of the reactant, added in the first batch. The whole assembly was kept in a heating mantel with controller. Temperature was maintained in the range of 100-120°C. The reaction was monitored by measuring the amount of water collected in the Dean-Stark apparatus. The same procedure was repeated for the remaining catalysts with different loading levels, care was taken in maintaining the amount of Zirconia in each batch constant i.e. for 2% loading exactly half quantity of catalyst was added to the first batch, for 3% one-third of the catalyst in the first batch was added and for 4% one- fourth of catalyst in the first batch was added.
Simple esterification of butanol and acetic acid was carried out using 1-4% loading of sulfated zirconia on silica. Concentration of zirconia was maintained constant in all the five batches. In the first batch, 5% catalyst was used by weight of the reactant and the percentage of zirconia was maintained constant for the remaining batches with varying loading levels of zirconia in the catalyst. The results are shown in Table 1. Product Butyl acetate was used as an entrainer for the co product water. The reaction was monitored by measurement of product water, which is the direct evidence of extent of reaction. This method of analysis was followed to avoid the disturbance in the reaction while sampling if analyses were to be carried out by determining acid value. On the basis of this data, the loading level of 1% was selected for the cracking reaction since atom efficiency was unaffected up to this level.
7

Various loading levels of Zirconia in catalyst to study butanol and acetic acid esterification is described in FIG 1.
TABLE 1 : Various loading levels of zirconia in catalyst to study butanol and acetic acid esterification

Catalyst 1% 2% 3% 4%
Loading
Time (hr) Catalyst Catalyst Catalyst Catalyst
Quantity Quantity Quantity Quantity
6.7g 3.35g 2.23g 1.17g
% Conversion
0.5 2.22 3.88 4.44 5.55
1 18.88 23.88 17.22 25
1.5 30.5 41.66 34.44 37.22
2 33.88 51.11 47.77 43.88
2.5 37.22 57.77 56.66 47.22
3 39.44 61.11 60.55 49.55
Example 2 Catalyst preparation
Silica gel with pore volume of 0.9 ml/g was prepared by potassium hydroxide leaching of the surface and used as a support for the catalyst preparation. The particle size of the silica gel was 2-5 mm. Dry silica gel was loaded with zirconium oxide as zirconium oxychloride with various loading levels from 1 to 4% from its aqueous solution. Calculated quantity of zirconium oxychloride on the basis of weight of silica was dissolved in water (volume of water equivalent to the pore volume of silica was taken). Weighed quantity of silica was soaked in zirconium oxychloride solution for 30 min .The loaded zirconium oxychloride was precipitated as zirconium hydroxide by exposing to ammonia vapours for 2-3 hrs. in a closed vessel, dried in an oven at 120°C for 12 hrs,
8

sulfated by using IN sulfuric acid followed by calcining at 450 C for 4hrs.This catalyst was then washed with water to remove traces of sulfuric acid and again calcined at 650°C for 2 hrs, cooled, crushed into powder of 40 mesh size and used for the experimental part.
Studies were made to optimize the catalyst composition for the performance and then established its reusability. Various loading levels of Zirconia incatalyst were studied for butanol and acetic acid esterification for optimization of the catalytic activity.
Example 3 Reusability Study:
After optimization of the catalyst the reusability of the catalyst was checked with esterification of butanol-acetic using a 2% Zirconia loaded catalyst. After the reaction was completed, the catalyst was separated by filtration. The catalyst was recycled to the next batch without further treatment. Additional fresh raw materials were added and further reactions were continued. The results of this reaction are given in TABLE No. 2, From the TABLE No. 2 and graphical representation of this data in FIG 2 it is observed that, there is no much difference in the results obtained, which implies the catalyst activity is consistent throughout the 5 batches, thus proving the reusability of the catalyst.
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TABLE 2: Catalyst Reusability study in Esterification of butanol with acetic acid

Time % Conversion
(hr)
BATCH BATCH BATCH BATCH
I II III IV
0.5 3.88 3.33 3.33 3.33
1.5 23.88 22.22 22.77 21.66
2.5 41.66 40 39.44 38.88
3.5 51.11 50.55 49.44 47.77
4.5 57.77 56.11 55.55 53.88
5.0 61.11 60.55 58.88 56.66
Results of Reusability study of the catalyst for butanol esterification is shown in FIG.2
Description of drawings
Various loading levels of Zirconia in catalyst to study butanol and acetic acid esterification are described in FIG.l.X axis (1) denotes time in hours and Y axis denotes conversion. Graphs 3, 4, 5 and 6 denote % conversion of the esterification reaction using 1,2, 3 and 4% catalyst respectively.
Results of Reusability study of the catalyst for Butanol Esterification is shown in FIG 2. X axis (7) denotes time in hours and Y-axis (8) denotes % conversion of esterification. Graphs 9, 10, 11 and 12 denote % conversion of esterification obtained by recycling catalyst in 4 batches.
While the present invention is described above in connection with preferred or illustrative embodiments, these embodiments are not intended to be exhaustive or limiting of the invention. Rather, the invention is intended to cover all alternatives, modifications and equivalents included within its spirit and scope, as defined by appended claims.
10

I Claim,
1. A process for preparation of recyclable Optimized Surface Supported Sulphated Zirconium Silicate Catalyst wherein, the said process comprises:
i) preparing silica gel with pore volume of 0.9 ml/g and
particle size of 2 to 5 mm by leaching of the surface with
potassium hydroxide solution; ii) drying the silica gel; iii) dissolving zirconium oxide as zirconium oxy chloride content
1 to 4 % on the basis of weight of silica in the water; iv) soaking the dry silica gel in the said zirconium oxychloride
aqueous solution for 20 to 30 minutes, more particularly for
30 minutes, to load / deposit the said zirconium oxy chloride
on dry silica gel; r*
v) precipitating said loaded / deposited zirconium oxy chloride
as zirconium hydroxide on silica gel by exposing to ammonia
vapors for 2 to 3 hours in closed vessels; vi) drying the said filtered precipitated zirconium hydroxide on
silica gel in an oven at 120°C for 12 hours; vii) sulfating the said dried the zirconium hydroxide on silica gel
by using IN sulfuric acid to sulfated zirconium on silica gel; viii) calcining the said sulfated zirconium at 450°C for 4 hours to
obtain sulfated zirconium silicate; ix) washing the said calcined sulfated zirconium silicate with
water to remove traces of sulfuric acid and x) calcining again the said washed sulfated zirconium silicate at
650°C for 2 hours; and
xi) cooling and crushing into powder of 40 mesh size for experimental and industrial use.

Documents:

1018-mum-2003- claims.doc

1018-mum-2003-cancelled pages(30-12-2004).pdf

1018-mum-2003-claims(granted)-(30-12-2004).doc

1018-mum-2003-claims(granted)-(30-12-2004).pdf

1018-mum-2003-claims.pdf

1018-mum-2003-correspondence(28-03-2006).pdf

1018-mum-2003-correspondence(ipo).pdf

1018-mum-2003-correspondence-(ipo)-(02-01-2003).pdf

1018-mum-2003-correspondence.pdf

1018-mum-2003-description(granted).doc

1018-mum-2003-description(granted).pdf

1018-mum-2003-drawing.pdf

1018-mum-2003-form 1(05-04-2004).pdf

1018-mum-2003-form 1(24-12-2004).pdf

1018-mum-2003-form 1(29-09-2003).pdf

1018-mum-2003-form 1(30-10-2003).pdf

1018-mum-2003-form 1.pdf

1018-mum-2003-form 19(30-10-2003).pdf

1018-mum-2003-form 2(granted)-(30-12-2004).doc

1018-mum-2003-form 2(granted)-(30-12-2004).pdf

1018-mum-2003-form 2(granted).doc

1018-mum-2003-form 2(granted).pdf

1018-mum-2003-form 2(title page).pdf

1018-mum-2003-form 26(30-10-2003).pdf

1018-mum-2003-form 3(29-09-2003).pdf

1018-mum-2003-form 3(31-12-2004).pdf

1018-mum-2003-form 3.pdf


Patent Number 207810
Indian Patent Application Number 1018/MUM/2003
PG Journal Number 30/2008
Publication Date 25-Jul-2008
Grant Date 28-Jun-2007
Date of Filing 29-Sep-2003
Name of Patentee MALSHE VINOD CHINTAMANI
Applicant Address 1, STAFF QUARTERS, UDCT CAMPUS, MATUNGA MUMBAI - 400 019.
Inventors:
# Inventor's Name Inventor's Address
1 MALSHE VINOD CHINTAMANI 1, STAFF QUARTERS, UDCT CAMPUS, MATUNGA MUMBAI - 400 019.
2 MAHESHWARI, KOMAL DIAMOND PPV Section, UICT, Matunga, Mumbai - 400 019.
PCT International Classification Number B01J 29/89
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA