WO2012056290A1

WO2012056290A1 - Ethyl oligo-silicates with strong acid heterogenous polymeric catalysts

Info

Publication number: WO2012056290A1
Application number: PCT/IB2011/002531
Authority: WO
Inventors: Mayank Dwivedi; Hari Sarvothama Rao Locanindi; Reddy Krishna Mohan Srinivasulu; Dhanasekharan Janakiraman; Madhusudana Rao Bevara; Rajesh Kumar Sriperambudur; Ponrathnam Surendra; Raman Rajan Chelanattukizhakkemadath; Kumar Tayal Rajiv; Mohammed Shadbar Qureshi; Nayaku Nivrati Chavan; Sarika Babasaheb Deokar; Khudbudin Baban Mulani; Ravindra Vasant Ghorpade; Sunil Sitaram Bhongale; Archana Chetan Nalawade; Kalpana Vishwanathrao Sontakke; Sonali Madhavrao Bhosle; Smita Atmaram Mule; Deepa Arun Dhoble
Original assignee: Director General, Defence Research & Development Organisation
Priority date: 2010-10-25
Filing date: 2011-10-24
Publication date: 2012-05-03
Also published as: IL225723A0; AU2011322203B2; KR20130102086A; BR112013010055A2; CN103180368A; KR101512580B1; CN103180368B; AU2011322203A1

Abstract

The present invention provides a process for the synthesis of ethyl silicate with varying silica concentration, by hydrolysing ethyl silicate in varying water concentration in the presence of sulfonated catalysts having a styrene-divinyl benzene backbone. The present invention further relates to the preparation of beaded crosslinked polymers containing sulfonic acid moieties having an interconnected pore structure and surface area up to 400 m² /g.

Description

ETHYL OLIGO-SILICATES WITH STRONG ACID

HETEROGENOUS POLYMERIC CATALYSTS

FIELD OF INVENTION

The present invention relates to the hydrolysis of ethyl silicate using sulfonated polymeric bead catalysts synthesized using high internal phase emulsion methodology. The present invention further relates to the preparation of beaded crosslinked polymer having aromatic rings present in the polymer backbone and is synthesized using water-in oil-in water emulsion technique which is further modified so as to introduce sulfonic acid groups on the polymer backbone.

BACKGROUND OF THE INVENTION

The tetraethyl ortho silicate (EtO)₄Si possess excellent thermal stability and liquid behavior over a broad temperature range. Ethylsilicate-32 is used as binders in paints and coatings. It is also used as room temperature silicone for vulcanizing cross linking agents. Ethyl silicate- 40 has a stable and long shelf life. It is primarily used as binders in paints, coatings, ceramic and precision casting and is also used as silicone room temperature vulcanizing agents. Ethyl silicate-28 is used as binders in paints, coatings, precision casting and ceramics. The number indicates the silica content present in the sample. Intermediate ethoxy derivatives of silicic acid and polysilicates are formed during the hydrolysis of ethyl silicate before the formation of silicon dioxide. The hydrolysis can be acid or base catalyzed. The rate of acid catalyzed hydrolysis is faster as compared to base catalyzed reactions and gives rise to more linear polymers due to sol gel transformation. Depending on the applications the catalysts can be chosen. For binder preparation dilute hydrochloric acid or sulphuric acid is used as it facilitates stable silanol condensation products. Basic catalysts like ammonia, ammonium carbonate are preferred when more complete condensation or gelation is preferred.

Hydrolysis of ethyl silicate in the presence of acidic and alkaline catalysts have been elaborated to produce ethyl silicate hydrolysates of the desired degree of hydrolysis by varying the reaction parameters such as catalyst concentration, water concentration, reaction temperature and time.

US4393230 describes the process for having a controlled process for predetermined silica content. Tetraethyl orthosilicate is prepared by reacting silicon tetrachloride and ethanol. If water is present in ethanol it forms ethyl polysilicate and if excess of ethyl silicate is present it forms polymeric products. By predetermined amounts of silicon dioxide (Si0₂) is meant within the range of the reaction wherein water is one of the reactants, which produces a product which contains about 28.8% Si0₂ , up to that amount where Si0₂ is precipitated out of solution (about 53% Si0₂ content). Therefore the stoichiometry involved in the complete hydrolysis of (EtO)₄Si and complete condensation of the hydrolysate can be represented as : (EtO)₄Si + 4HOH ► 4EtOH + Si(OH)₄

Si(OH)₄ ► 2 HOH + Si0₂

(EtO)₄Si + 2 HOH ► 4EtOH + Si0₂

The equations indicate that 2 moles of water would be required for the complete hydrolysis of 1 mole of (EtO)₄Si. The hydrolysis reaction is random so that an amount of water equivalent to partial hydrolysis would yield initially a distribution of (EtO)₄Si, (EtO)₃SiOH, (EtO)₂Si(OH)₂, (EtO)Si(OH)₃ and Si(OH)₄

The reaction can be monitored with the disappearance of water and appearance of ethanol. US4290811 describe a process for hydrolysis of ethyl silicate in presence of strong acid ion exchange resin instead of conventional acid catalyst. The conventional acids used are sulphuric acid and hydrochloric acid but the residual acidity can create problems of instability of ethyl silicate and pot life stability. The use of heterogeneous catalyst minimizes the work up procedure and problems related to removal of acid traces left behind in the reaction mixture. Conventional ion exchange resins like Amberlyst 15 (trade mark of Rohm and Hass Company) have been reported for the hydrolysis of ethylsilicate. The chief disadvantage of the reactions done using homogeneous catalysts is contamination of product due to presence of catalyst such as sulfuric acid and the necessity of an additional difficult and expensive unit operation for the removal of catalysts by treating with salts that may be critical during processing and applications of the resin, disposal of the waste generated by treatments. This can be circumvented using heterogeneous catalysts which may be removed easily by filtration after the reaction and reused many times without loss in catalyst activity. The present invention relates to hydrolysis of tetraethyl orthosilicate using a highly porous polymeric catalyst, very much higher than Amberlyst-15 having styrene divinyl benzene backbone. The cross-linked polymer is synthesized in beaded form using high internal phase emulsion methodology. The polymers have interconnected pore structure, variable surface area in the range of 100-400 m /g depending on the synthesis strategy while the surface area of commercially available macroreticular resin Amberlyst-15 is 42.5 m /g as reported by R. Kunin, E. A. Meitzner, J. A. Oline, S. A. Fischer, N. Frish (Ind. Eng. Chem. Prod. Res. Dev., 1962, 1 (2), pp 140-144). The aromatic ring on the polymer backbone is postmodified to adhere the sulfonic acid moieties onto it. The surface accessible sulfonic acid groups determine the catalytic efficiency of the heterogeneous catalyst. The problems like charring of the reaction mixture by direct use of the strong acid are circumvented by the use of heterogeneous acid catalyst. The present inventors have surprisingly found that use of catalysts such as beaded polymers containing sulfonic acid moieties prepared by High internal phase emulsion polymer technique provides for efficient hydrolysis of ethyl silicate so as to provide catalysts with silica content in the range 32-40%.

Beaded polymers containing sulfonic acid moieties can be synthesised using suspension polymerization methodology to be used in chromatographic applications. The bead size, particle size distribution, surface accessible functional groups, pore structure and porosity play an important role in the efficiency of the polymer application. The properties of the polymers are dependent on the reaction parameters like protective colloid type and nature, stirring speed, reactivity ratio of monomer and crosslinker. The beads can be post modified to introduce functional groups like sulphonic acid, amine, hydroxyl, t-butyl so as to make the polymer support hydrophobic or hydrophilic to be used in chromatographic applications such as ion exchange, gel filtration, adsorption and affinity chromatography. US 5863957 describes a process for synthesis of porous crosslinked polymeric microbeads having cavities joined by interconnecting pores wherein at least some of the cavities are connected to the outer surface. OBJECT OF INVENTION

It is the primary object of the invention to provide a process for the synthesis of ethyl silicate with varying silica concentration.

It is an object of the invention to provide a process for the hydrolysis of ethyl silicate in the presence of sulfonated catalyst synthesized using high internal phase emulsion methodology.

It is an object of the invention to provide a process for the hydrolysis of ethyl silicate in the presence of beaded crosslinked polymers containing sulfonic acid moieties and synthesized using high internal phase emulsion methodology and having an interconnected pore structure

It is yet another object of the invention to provide a process for the synthesis of beaded crosslinked polymers having an interconnected pore structure and surface area up to 400 m²/g. It is yet another object of the invention to prepare beaded crosslinked polymers which is post modified to provide sulfonic acid groups in the polymer backbone. SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a process for the hydrolysis of ethyl silicate comprising the steps of:

a) Adding tetraethyl orthosilicate and water in the range of 0.5 to 5 wt% of tetraethylorthosilicate to a container;

b) Adding sulfonated polymeric beads having surface area in the range of 100 m2/g to 400 m /g to the reaction mixture;

c) Heating the reaction mixture to upto 60°C and maintaining it for up to 10 hours;

d) Analysing the reaction mixture for tetraethyl orthosilicate and ethanol;

e) Determining the amount of silica content;

f) Removing the sulfonated polymeric beads after the reaction is complete;

g) Optionally reusing the sulfonated polymeric beads for the hydrolysis process.

According to another aspect of the invention, there is provided a process for the preparation of polymeric beads bearing sulfonic acid moieties on the polymer backbone with an interconnected pore structure and comprising the steps of:

a) Preparing water in oil phase emulsion by the following steps:

i) combining an oil phase containing styrene as monomer, crosslinker, surfactant, porogen and initiator;

ii) Adding aqueous discontinuous phase to the oil phase to form a water in oil emulsion under constant stirring;

b) Adding the water in oil emulsion to an aqueous phase containing a protective colloid under constant stirring at a rate of 250-500 rotations per minute;

c) Polymerizing the emulsion droplets under constant stirring at higher temperature for a period of upto 12 hours to obtain polymeric beads having a surface area of up to 400 m²/g ;

d) Adding sulfuric acid to the polymeric beads and heating at 110°C for a period of 24 hours to obtain sulfonated polymeric beads. DETAILED DESCRIPTION OF INVENTION

The present invention provides a process for having a controlled silica concentration in ethyl silicate i.e. Si0₂ content. This can be achieved by hydrolysis of ethyl silicate using requisite quantity of water in presence of a sulfonated polymeric bead catalyst such as beaded crosslinked polymers containing sulfonic acid moieties.

The hydrolysis of ethyl silicate comprises the steps of:

c) Heating the reaction mixture to 60°C and maintaining it for up to 10 hours;

d) Analysing the reaction mixture for tetraethyl orthosilicate and ethanol;

e) Determining the amount of silica content;

f) Removing the sulfonated polymeric beads after the reaction is complete;

In an embodiment of the invention, hydrolysis of tetraethyl ortho silicate is done by varying the concentration of water depending on the quantity of Si0₂ required in the product.

In yet another embodiment, the hydrolysis is carried out with variation in concentration of water and sulfonated polymeric bead catalyst. In yet another embodiment the hydrolysis is carried out in the presence of used sulfonated polymeric bead catalyst.

The molar ratio of tetraethyl ortho silicate and water is in the range 1 :0.0065 upto 1 :0.64. The molar ratio of tetraethyl ortho silicate and sulfonated polymeric bead catalyst is 1:0.1.

The molar ratio of water and sulfonated polymeric bead catalyst is in the range 1:0.15 upto 1 :1.54.

The surface area of the catalyst used is in the range 100- 400 m /g and is preferably in the range of 100- 350 m²/g.

The percentage of hydrolysis and the silica content of the hydrolysed product depend on the quantity of water used which is preferably in the range of 0.5 to 5% of tetraethyl orthosilicate.

The present invention further relates to the synthesis of beaded crosslinked porous polymers having interconnected pore structure. The process deals with polymerization of oil in water type emulsion by suspension polymerization technique to generate polymers in beaded form.

The process consists of two steps. It is a water-in-oil-in-water emulsion i.e. the innermost water phase is surrounded by oil phase which in turn is surrounded by external phase. In first step, water in oil emulsion is prepared and in the second phase oil in water emulsion is formed by suspending the water in oil emulsion in the form of droplets in a reactor containing protective colloid which is stirred at constant rpm. So the second phase forms oil in water emulsion and hence the polymerization is water in oil in water type of system.

The process for the preparation of polymeric beads having an interconnected pore structure and having sulfonic acid moieties on the polymer backbone comprising the steps of:

a) Preparing water in oil phase emulsion by the following steps:

i) combining an oil phase containing styrene monomer, crosslinker, surfactant, porogen and initiator; ii) Adding aqueous discontinuous phase to the oil phase to form a water in oil emulsion under constant stirring at a rate of 350-1400 rotations per minute;

b) Adding the water in oil emulsion to an outer aqueous phase containing a protective colloid under constant stirring at a rate of 300 rotations per minute;

d) Adding sulfuric acid to the polymeric beads and heating at 110°C for a period of 24 hours to obtain sulfonated polymeric beads.

The monomer used in the present invention is styrene. The concentration of monomer in oil phase is 80% with respect to surfactant and initiator.

The crosslinker used in the present invention is selected from divinyl benzene, ethylene dimethacrylate.

The concentration of the crosslinker to be used in the present invention varies from 0.05 to 2.0 times of the monomer concentration.

The concentration of monomer in oil phase is 15 wt % with respect to surfactant and initiator. The initiator used is 2,2'-azobisisobutyronitrile and is 3 mole % of monomer phase.

The surfactant to be used in the present invention is Span in the range of Span 20 to Span 80.

The porogen to be used in the present invention is selected from chlorobenzene, toluene and heptane. The ratio of the monomer to porogen in the present invention varies from 1 : 0.5 to 1 : 2.

The porogen concentration comprises of 50 % upto 200 % of the monomer.

The pore volume range depends on the porogen used and is preferably in the range of 0.2 cm /g to 0.6 cm /g.

The surface accessible functional groups are in the range of 2.8-3.9 milli equivalents per gram.

In formation of water in oil phase the water can be 5:1 upto 30:1 with respect to monomer and during suspension polymerization is 10 times to 20 times of the oil phase.

The stirring speed during the preparation of water in oil phase emulsion can be varied from 350 rotations per minute to 1400 rotations per minute.

The protective colloid prevents the coalescence of the polymeric beads during the sticky period of polymerization and polymer is obtained in the form of beads at the end of the reaction. The basic function of protective colloid is to increase the viscosity of the aqueous phase. The protective colloid to be used in the present invention is selected from poly vinyl (pyrrolidone), poly (vinyl alcohol), sodium chloride or calcium chloride.

The concentration of protective colloid to be used in the present invention varies from 0.5 wt % up to 2 wt % of the aqueous phase. The stirring speed of the suspended particles in the present invention can be varied from 250 rotations per minute up to 500 rotations per minute.

EXAMPLES

The process of the present invention is described herein below with reference to the following examples, which are only illustrative in nature and should not be construed to limit the scope of the invention in any manner.

Example 1

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate with 28% silica content and 0.05 g (0.0028 mol) of water are taken. To the reaction mixture 1.032 g of sulfonated (poly (styrene-divinyl benzene) catalyst having surface area of 330 m²/g and synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of ten hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas Chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. 33.3% of hydrolysis was achieved with respect to ethyl silicate and silica content was determined by gravimetric method and was found to be about 30 %. Example 2

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.100 g (0.0056 mol) of water are taken. To the reaction mixture 1.032 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of ten hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. 46% of hydrolysis was achieved with respect to ethylsilicate and silica content was determined by gravimetric method and was found to be about 32 %. Example 3

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.201 g (0.0112 mol) of water are taken. To the reaction mixture 1.032 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of ten hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. 50% of hydrolysis was achieved with respect to ethylsilicate and silica content was determined by gravimetric method and was found to be about 34 %.

Example 4

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.502 g (0.0279 mol) of water are taken. To the reaction mixture 1.032 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of ten hours.

The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. 87% of hydrolysis was achieved with respect to ethylsilicate and silica content was determined by gravimetric method and was found to be about 37 %.

Example 5

The reaction as illustrated in Example 2 was repeated to check the reusability of the catalyst. The concentration of ethanol and tetra ethyl orthosilicate in the reaction mixture was analyzed using gas chromatography and silica content by gravimetric analysis, is as follows: Cycle % Ethanol % tetraethyl % Silica content

orthosilicate

1 60.4 12.8 42

2 13.1 52.2 33

3 12.2 69.7 30

The silica content in the starting tertaethylorthosilicate is 28%. The amount of water used is 0.1 g (0.0056 mol). Example 6

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.05 g (0.028 mol) of water are taken. To the reaction mixture 0.516 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of ten hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. The silica content was determined by gravimetric method and was found to be about 30 %. Example 7

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.05 g (0.028 mol) of water are taken. To the reaction mixture 1.548 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of ten hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. The silica content was determined by gravimetric method and was found to be about 34 %. Example 8

The reaction as illustrated in Example 2 was repeated with varying reaction time and reaction temperature keeping the other parameters same. The silica content was analyzed by gravimetric analysis:

When the reaction was run for two and half hours, the silica content obtained was 30% and when the reaction was run for five hours, the silica content obtained was 36%.

When the reaction was run for ten hours at 40°C, the silica content obtained was 38% and when the reaction was run for ten hours at 80°C, the silica content obtained was 45%.

Example 9

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.05 g (0.0028 mol) of water are taken. To the reaction mixture 0.516 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 60°C for a period of five hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas Chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. The silica content was determined by gravimetric method and was found to be about 32 %.

Example 10

In a stoppered plastic container 9.020 g (0.0433 mol) tetraethyl orthosilicate and 0.05 g (0.0028 mol) of water are taken. To the reaction mixture 0.516 g of sulfonated (poly (styrene- divinyl benzene) synthesized using high internal phase emulsion polymerization methodology was added. The reaction mixture was heated at 40°C for a period of five hours. The reaction mixture was then analysed for tetraethyl orthosilicate and ethanol by gas Chromatography (GC). The reaction mixture is then filtered to remove the heterogeneous catalyst followed by distillation to remove ethanol. The silica content was determined by gravimetric method and was found to be about 32 %. Example 11

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 80 surfactant and 0.15 g (9.34x1ο^"4 mole) of azobisisobutyronitrilej 4.5 mL chlorobenzene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 298 m7g.

Sulphonation of beads: All the polymers synthesized as illustrated in Examples 1 to 5 are subjected to post modification reaction to introduce sulphonic acid groups on the polymer backbone.

For 8.96 g (100 % CLD) poly(styrene-di vinyl benzene) beads, 45 mL (98 %) sulphuric acid (0.449 mol) is added. The reaction mixture is heated at 110°C for a period of 24 hours. After the reaction is completed the reaction mixture is poured in water. The beads are filtered and washed several times with water. The beads are dried overnight in a vacuum oven at 80°C. Example 12

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 80 surfactant, 0.15 g (9.34X10^"4 mole) of azobisisobutyronitrile and 4.5 mL toluene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of293 m7g.

The sulfonation step is carried out in the same manner as described in example 11. Example 13

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 80 surfactant, 0.15 g (9.34x1ο^-4 mole) of azobisisobutyronitrile and 4.5 mL heptane as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of357 m²/g.

The sulfonation step is carried out in the same manner as described in example 11.

Example 14

Preparation of water in oil phase (ΗΓΡΕ): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 1.116 g Span 80 surfactant, 0.15 g (9.34x1ο^-4 mole) of azobisisobutyronitrile and 4.5 mL chlorobenzene as porogen (continuous phase) is taken. 98.16 mL of deionised water (discontinuous phase) are added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 333 m²/g. Example 15

Preparation of water in oil phase (ΉΙΡΕ): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 1.116 g Span 80 surfactant, , 0.15 g (9.34x1ο^"4 mole) of azobisisobutyronitrile and 4.5 mL toluene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring, rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled;, filtered, washed several times with water and then dried. The beads obtained had a surface area of274 m²/g.

Example 16

Preparation of water in oil phase (HIPE : In a container 1.54 g (0.0148 mol) styrene monomer, 2.94 g (0.0148 mol) crosslinker ethylene glycol dimethacrylate, 0.982 g Span 80 surfactant, 0.15 g (9.34x1ο^-4 mole) of azobisisobutyronitrile and 5.4 mL toluene as porogen (continuous phase) are taken. 116.3 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 114 m /g.

Example 17

Preparation of water in oil phase (HIPE): In a container 1.54 g (0.0148 mol) styrene monomer, 2.94 g (0.0148 mol) crosslinker ethylene glycol dimethacrylate, 0.982 g Span 80 surfactant, 0.15 g (9.34x1ο^"4 mole) of azobisisobutyronitrile and 5.4 mL chlorobenzene as porogen (continuous phase) are taken. 116.3 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 108 m²/g.

Example 18

Preparation of water in oil phase (HIPE): In a container 1.54 g (0.0148 mol) styrene monomer, 2.94 g (0.0148 mol) crosslinker ethylene glycol dimethacrylate, 1.346 g Span 80 surfactant, 0.15 g (9.34x1ο^"4 mole) of azobisisobutyronitrile and 5.4 mL chlorobenzene as porogen (continuous phase) are taken. 116.3 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 133 m²/g.

Example 19

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 20 surfactant, 0.15 g (9.34x10^"4 mole) of azobisisobutyronitrile and 4.5 mL chlorobenzene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 275 m /g. Example 20

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 20 surfactant, 0.15 g (9.34x1ο^"4 mole) of azobisisobutyronitrile and 4.5 mL toluene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 1 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 250 m g.

Example 21

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 80 surfactant, 0.15 g (9.34x1ο^-4 mole) of azobisisobutyronitrile and 4.5 mL toluene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes. Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 2 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of 275 m²/g.

Example 22

Preparation of water in oil phase (HIPE): In a container 1.65 g (0.0158 mol) styrene monomer, 2.07 g (0.0158 mol) crosslinker divinyl benzene, 0.818 g Span 80 surfactant, 0.15 g (9.34x1ο^"4 mole) of azobisisobutyronitrile and 4.5 mL chlorobenzene as porogen (continuous phase) are taken. 98.16 mL of deionised water (discontinuous phase) is added to the oil phase with constant stirring of 1400 rpm to obtain water in oil emulsion for a period of 10 minutes.

Suspension polymerization of the oil phase: The suspension polymerization is carried out in a double walled cylindrical glass reactor maintained at a constant temperature, equipped with a condenser, nitrogen inlet and overhead stirrer with constant stirring. The water in oil emulsion prepared as above is added to the suspension reactor comprising of a 200 mL aqueous phase with 0.5 wt % protective colloid at a constant stirring rate of 300 rotations per minute. After the complete addition of the water in oil phase to the outer aqueous phase the temperature of reactor is increased upto 70°C and maintained for a period of 12 hours. After the completion of the reaction time the product obtained in the form of beads is cooled, filtered, washed several times with water and then dried. The beads obtained had a surface area of290 m /g.

Claims

1) A process for the hydrolysis of ethyl silicate comprising the steps of:

a) Adding tetraethyl orthosilicate and water in the range of 0.5 to 5 wt% of tetraethyl orthosilicate to a container;

b) Adding sulfonated polymeric beads surface area in the range of 100 m2/g to 400 m /g.to the reaction mixture;

d) Analysing the reaction mixture for tetraethyl orthosilicate and ethanol;

e) Determining the amount of silica content;

f) Removing the sulfonated polymeric beads after the reaction is complete;

2) A process for the hydrolysis of ethyl silicate according to claim 1, wherein the molar ratio of tetraethyl ortho silicate and water is in the range 1 :0.0065 upto 1 :0.64.

3) A process for the hydrolysis of ethyl silicate according to claim 1, wherein the molar ratio of tetraethyl ortho silicate and sulfonated catalyst is 1:0.1

4) A process for the hydrolysis of ethyl silicate according to claim 1, wherein the molar ratio of water and sulfonated catalyst is in the range 1:0.15 upto 1:1.54.

5) A process for the preparation of polymeric beads bearing sulfonic acid moieties on the polymer backbone with an interconnected pore structure and comprising the steps of:

a) Preparing water in oil phase emulsion by the following steps:

b) Adding the water in oil emulsion to an aqueous phase containing a protective colloid under constant stirring at a rate of 250-500 rotations per minute; c) Polymerizing the emulsion droplets under constant stirring at higher temperature for a period of upto 12 hours to obtain polymeric beads having a surface area of upto 400 m²/g ;

6) A process for the preparation of polymeric beads according to claim 5, wherein the concentration of styrene monomer in oil phase is 80% with respect to surfactant and initiator.

7) A process for the preparation of polymeric beads according to claim 5, wherein the crosslinker is selected from divinyl benzene and ethylene dimethacrylate and is present in the range 0.05 to 2.0 times of the monomer concentration.

8) A process for the preparation of polymeric beads according to claim 5, wherein the initiator used is 2,2'-azobisisobutyronitrile and is 3 mole % of monomer phase.

9) A process for the preparation of polymeric beads according to claim 5, wherein the surfactant to be used in the present invention is Span 20 to Span 80.

10) A process for the preparation of polymeric beads according to claim 5, wherein the porogen is selected from chlorobenzene, toluene and heptane.

11) A process for the preparation of polymeric beads according to claim 5, wherein the ratio of the monomer to porogen in the present invention varies from 1 : 0.5 to 1 : 2.

12) A process for the preparation of polymeric beads according to claim 5, wherein the protective colloid to be used is selected from poly vinyl (pyrrolidone), poly (vinyl alcohol), sodium chloride or calcium chloride and is present in the range 0.5 wt % to 2 wt % of the aqueous phase.

13) A process for the preparation of polymeric beads according to claim 5, wherein the pore volume of the polymeric beads is in the range 0.2 cm /g to 0.6 cm /g.

14) A process for the preparation of polymeric beads according to claim 5, wherein the surface accessible functional groups on the polymeric beads are in the range of 2.8-3.9 milli equivalents per gram.