Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF INTERCALATED CLAY COMPOSITES USEFUL AS SOLID ACID CATALYSTS"
Abstract	An improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) the present invention provides, an improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) useful as solid acid catalysts , by treating aqueous suspension said expandable Montmorillonite clay dispersed under ultrasonic vibration with metal salt (MX) where M = Zn, Cu, Ni, X = halide for a period of about 24 hours followed by dialysis to obtain a pure electrolyte free solid composite (Mn+ - Montmorillonite ) , dispersing in aqueous medium to make slurry and then treated with concentrated aqueous solution of 0.5 - 2.5 Molar metal salt (MX) where M = Zn, Cu, Ni, etc. X = halide; under ultrasonic vibration and subsequently dried at about 80°C to obtain a homogeneous metal-metal salt-Montmorilonite composites which are finally activated in the temperature range 100° - 300°C .

Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF INTERCALATED CLAY COMPOSITES USEFUL AS SOLID ACID CATALYSTS"

Abstract

An improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) the present invention provides, an improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) useful as solid acid catalysts , by treating aqueous suspension said expandable Montmorillonite clay dispersed under ultrasonic vibration with metal salt (MX) where M = Zn, Cu, Ni, X = halide for a period of about 24 hours followed by dialysis to obtain a pure electrolyte free solid composite (Mn+ - Montmorillonite ) , dispersing in aqueous medium to make slurry and then treated with concentrated aqueous solution of 0.5 - 2.5 Molar metal salt (MX) where M = Zn, Cu, Ni, etc. X = halide; under ultrasonic vibration and subsequently dried at about 80°C to obtain a homogeneous metal-metal salt-Montmorilonite composites which are finally activated in the temperature range 100° - 300°C .

Full Text	The present invention relates to an improved process for the preparation of intercalated clay composites useful as solid acid catalysts. The process of the present invention particularly relates to the preparation of intercalated clay composites by exchanging suitable metal cations with the exchangeable cations in the interlamellar spacing of expandable layered aluminosilicates (like smectite group clays). This invention is more particularly related to preparing efficient metal(cation)-metal salts - expandable clays (smectite, or the likes) composites useful as solid Bronsted and Lewis acid catalysts for alkylation reactions or the like organic reactions. Supported inorganic reagents are rapidly emerging as a new and environmentally accepted materials for improving process efficiency or to replace environmentally unacceptable reagents and catalysts. Attempts are being made to replace highly corrosive HF in olefin alkylation, anhydrous A1C13 in Friedel Crafts alkylation etc. by supported solid acid catalyst. All the solid acids are characterized by the presence of protons or coordinatively unsaturated cationic centers on the surface leading to Bronsted and Lewis acidity. Bronsted acidity comes from exchangeable cations which polarize interlayer water molecules. Partial dehydration increases the acidity. Replacement of the exchangeable interlayer Na by high charge density cations such as Al , Zn etc. leads to acidity as high as 10 mol dm . These highly acidic forms of Montmorillonite clays have been described as broad spectrum catalysts for organic synthesis. It is also important to note that at high temperatures clays are generally reduced to Lewis acidity only through the loss of interlayer water. Swelling clays with layered structures offer the potential for shape selectivity although the interlayer gap in natural Montmorillonite can remain quite small. The replacement of interlayer Na by cations as Fe , Al etc. leads to clay layers of high acidity and are described (J. A. Ballantine, J. H. Purnell and J. M. Thomes, J. Mol. Cat., 27 (1984) 157) as broad spectrum catalysts for organic synthesis. Replacement of environmental unacceptable anhydrous A1C13 , an established catalyst for Friedel Crafts alkylation, by supported A1C13 on K-10 montmorillonite has been claimed (J. H. Clark, K. M. Andrew, A. J. Teasdale and S. J. Barlow, J. Chem. Soc. Chem. Com. (1995) 2037) to be an efficient catalyst. Anchoring of A1C13 on the hydroxy groups of the supporting materials may occur (R. S. Drago and E. E. Getty, J. Am. Chem. Soc. 110 (1988) 3311) through the active group -O-A1C12. Smectite clays have been shown to be very effective supports for a number of transitional metal salts. One such example is supported ZnCL -K-10-Montmorillonite clay which is prepared by digesting methanoic solution of ZnCL with acid treated Montmorillonite(K-l0). When the loading is very high, the catalytic activity is low and this may be attributed to the aggregation of ZnCl2 on the support. The metal salt is believed to stay as intact molecule residing within the pores of the support. Therefore, leaching of the metal salt from the support is very much likely and the catalytic activity is expected to be reduced accordingly. In order to overcome the narrow interlayer distance, a new class of pillared materials have been developed (D. E. W. Vaughan, R. T. Lussier and J. Magee (1979), US Patent No. 4176090) by exchanging Na-montmorillonite with inorganic polyoxo metal ions like (Al13) of larger size and charge and then calcining at about 450 °C for 4 hours. Metal ion exchanged catalysts were prepared (M. P. Atkins, Pillared layered structures, Current trend and application, Ed. I. V. Mitchell, Elsevier, Appl. Sc. (1990, 159) by treating the pillared clay with desired cations. The actual location of the cation exchange site in pillared clays is still not known. Such materials are also called "Pillared Clay" show higher interlayer spacing (about 10-12 A). Despite their high thermal stability (> 5000 C) and high surface area (> 200 m2 /g), pillared clays are less efficient catalysts compared to cations (like Al ) exchanged clays. The present invention is distinguished from the prior art in that it does not involve any acid treatment for modifying the solid matrix support of the Montmorillonite clay as used for generating Montmorillonite(K-l0). The present invention also does not involve high temperature for modifying the clay-support as required for developing "Pillared Clay" composites. The present process consists of simple two stage reaction steps; in the first step - the interlayer sodium (Na+) ions of the layered clay (Montmorillonite) are replaced by ion exchange with suitable metal ions (Mn+) like Ni, Cu, Zn etc. to produce homoionic intercalated Mn+- Montmorillonite layered composites followed by dialysis to purify the composite. In the second step - the pure Mn+- Montmorillonite is well dispersed into aqueous medium under ultrasonic vibration followed by treatment with calculated amount of metal salt (MX) where X = halide; to deposite as salt into interlayer spacing as well as on the surface of the layered Mn+-Montmorillonite to produce layered Mn+-MX-Montmorillonite composites which are activated in the temperature range 100 -300°C for 1-12 hours to generate a novel metal ion-metal salt active sites bearing layered clay composite for using as solid acid catalysts in organic synthesis. These composites can behave as novel solid acid catalyst because they contain two different functional active metal sites i.e. one in the interlayer spacing of the clay and the other on the surface of the clay layers leading to simultaneous generation of two different acidic properties i.e. BrOnsted and Lewis acidity. The main object of the present invention is to provide a process for preparing metal(cation)-metal salt-clay(expandable) composites useful as solid acid catalysts which obviates the draw back as described above. Still another object of the present invention is to provide a simple process of preparing solid acids with BrOnsted and Lewis acid sites for catalysing organic reactions. Accordingly the present invention provides, an improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) useful as solid acid catalysts , characterized in that intercalation of metal cations into the interlamellar spacing of Montmorillonite clay layer by the treatment of expandable Montmorillonite clay dispersed under ultrasonic vibration with metal salts (MX) where M = Zn, Cu, Ni, X = halide , which comprises treating 1% aqueous suspension said expandable Montmorillonite clay dispersed under ultrasonic vibration with 1 molar said metal salt for a period of about 24 hours followed by dialysis to obtain a pure electrolyte free solid composite (Mn+ -Montmorillonite ) which is again dispersed in aqueous medium to make slurry and then treated with concentrated aqueous solution of 0.5 - 2.5 Molar metal salt (MX) where M = Zn, Cu, Ni, etc. X = halide; under ultrasonic vibration for a period of 1 hour and subsequently dried at about 80°C in air oven to obtain a homogeneous metal-metal salt-Montmorilonite composites which are finally activated in the temperature range 100° - 300°C for a period 1-24 hours before using as solid acid catalysts. In an embodiment of the present invention, the oxidic compositions of the montmorillonite clays of M/S Neelkanth Soda Clays & Pulveriser, Jodhpur, India and Na-montmorillonite, SWY-2, Wyoming, USA, after purification are shown (Table 1). Tablet. Chemical composition of clays: (Table Removed) The different process steps of the present invention are given below : Purification of the clays (Montmorillonite): The Bentonite powder (M/S Neelkanth) and Na-montmorillonite (Wyoming) were purified by standard gravity settling technique and the -2 (a. m fraction was collected in order to obtain the montmorillonite fraction. About 50 g of Bentonite powder or Na-montmorillonite clay was suspended in 1000 ml distilled water by stirring for half an hour and was set aside for about 24 hrs. The suspension upto 10 cm height from the top of the surface of the suspending liquid was collected for -2µ, m particle size. The mass was then dried above 50 ± 5° C in air oven. This fraction of the clay was rich in montmorillonite. Conversion into Na-montmorillonite : About 2 g of dry purified clay was suspended into 100 ml of distilled water and to it 100 ml of 2 M NaCl solution was added and kept stirring for about 12 hrs. The mass was allowed to settle and the supernatant liquid was decanted off. The slurry was again treated with NaCl solution and stirred. This step was repeated for about 4 times. The excess NaCl was removed by washing with distilled water and finally dialysed till the conductivity of water is Oriented film was prepared from the dialysed Na-montmorillonite on glass slide by allowing about 1 ml suspension to dry at room temperature. The basal spacing (d001) as determined by XRD technique was found to be about 12 A for the room temperature dried sample. The slide was then kept in a desiccator over ethylene glycol for about 12 hrs. The d001 value obtained at 16.5 A indicated the identification of montmorillonite clay. Cation Exchange Capacity (CEC) : About 0.5 g of the clay was treated with alcoholic solution of CaC12 containing 4 Eqv. CEC (considering 100 meq. / 100 g clay) and kept overnight under stirring condition. ++ The difference in the concentration of CaCl2 gave the amount of Ca exchanged. Then about 0.5 g clay was treated with ammonium acetate solution containing about 4 Eqv. CEC. of the clay under stirring condition and the liberated CaCl2 was determined. From these exchanged data, the total CEC was determined. The CEC determined for the M/S Neelkanth and Wyoming clays were 114 and 90 meq. /100 g of clay respectively. Montmorillonite is composed of layered lattice structure and each sheet is composed of octahedral alumina sandwiched by two tetrahedral sheets of silica. The negative charge on the surface of these layers are, in general, developed by the isomorphous substitution of alumina in octahedral layer by lower valent cations like magnesium or iron. These negative charges are then counter balanced by exchangeable cations like Na , Ca , Mg residing mostly in the interlayer space. These layered structures enable intercalation of other compounds of different characteristics between the sheets of the clay. Adsorption of water expands the interlayer distance to a great extent (> 40 A). Upon heating at about 150° C, most of the interlayer water is lost and the layers of the clay approach closer to each other and leave very narrow interlayer space. The basal spacing i.e. the distance from the top of a layer to the top of the immediate layer, of Na-exchanged montmorillonite dried at 110° C for 2 hrs., show a value of about 12 A . The basal spacing for a fully collapsed matrix is about 9. 6 A i.e. the layer thickness. Such composite materials are very much potent in respect of developing BrOnsted and Lewis acids. Bronsted acidity is generated by the polarizing power of the exchanged cations i.e. Al , Zn ions. Such cations produce Bronsted acid strength by promoting a reaction with water to release H ions - [M(H20)x]+ H20 → [M(H20)x-l(OH)] As the clay surface loses moisture, the reaction is driven further to the right and the protons are concentrated in a smaller volume of water. Air dried smectite with Al exchange ions are equivalent in acidities to concentrated aqueous solutions of strong acids. When the interlayer water is lost due to heating at higher temperature, the metal ion exchanged montmorillonite behaves as Lewis acids. Therefore, depending upon the water content of the composites, the nature as well as the strength of acidity depends. These types of acidity of the composites are useful as solid acid catalysts in organic synthesis. The following examples are given by way of illustrations of the present invention and should not be construed to limit the scope of the invention. Example 1 : . 3.0 g of dried Na-montmorillonite clay (Wyoming) or Neelkantha Bentonite having size fraction of -2 µ m fraction was dispersed in about 300 ml of distilled water under constant stirring and then mixed thoroughly under ultrasonic vibration for about 10 min. To this homogeneous suspension. 25 ml solution containing 0.54g of NiCl2.6H20 was added slowly and stirred for, 24 hours and then dialysed till the solution was free from chloride. The mass was collected and dried at about 80 °C . About 1 gm of the Ni-Montmorillonite composite was dispersed in 100 ml of distilled water and stirred for about 2 hours and to this slurry 1.54 ml of 1(M) NiC12 solution was added drop wise and subjected to ultrasonic vibration for about 1 hour. The whole mass was then dried in an air oven at about 80 °C to obtain Ni-NiC12-Montmorillonite composite. The dried mass was then activated in the temperature range 100 to 300 °C for 1 to 24 hours before using as solid acid catalyst in organic synthesis like Friedel Crafts Reaction for alkylation of benzene. Example 2 : 3.0 g of dried Na-montmorillonite clay (Wyoming) or Neelkantha Bentonite having size fraction of -2 µ m fraction was dispersed in about 300 ml of distilled water under constant stirring and then mixed thoroughly under ultrasonic vibration for about 10 min. To this homogeneous suspension. 25 ml solution containing 0.398g of CuC12.H2O was added slowly and stirred for . 24 hours and then dialysed till the solution was free from chloride. The mass was collected and dried at about 80 °C . About 1 gm of the Cu-Montmorillonite composite was dispersed in 100 ml of distilled water and stirred for about 2 hours and to this slurry 1.52 ml of 1 (M) CuC12 solution was added drop wise and subjected to ultrasonic vibration for about 1 hour. The whole mass was then dried in an air oven at about 80 °C to obtain Cu-CuC12-Montmorillonite composite. The dried mass. was then activated in the temperature range 100 to 300 °C for 1 to 24 hours before using as solid acid catalyst in organic synthesis like Friedel Crafts Reaction for alkvlation of benzene. Example 3 : 3.0 g of dried Na-montmorillonite clay (Wyoming) or Neelkantha Bentonite having size fraction of-2 µ m fraction was dispersed in about 300 ml of distilled water under constant stirring and then mixed thoroughly under ultrasonic vibration for about 10 min. To this homogeneous suspension, 25 ml solution containing 0.348g of ZnC12.2H2O was added slowly and stirred for about 24 hours and then dialyzed till the solution was free from chloride. The mass was collected and dried at about 80 °C . About 1 gm of the Zn-Montmorillonite composite was dispersed in 100 ml of distilled water stirred for about 2 hours and to this slurry 1.53 ml of 1(M) ZnC12 solution was added dropwise and stirred for about 24 hours. The whole mass was then dried in an air oven at about 80 °C to obtain Zn-ZnC12-Montmorillonite composite. The dried mass was then activated in the temperature range 100 to 300 °C for 1 to 24 hours before using as solid acid catalyst in organic synthesis like Friedel Crafts Reaction for alkvlation. Example 4: 1.70 g (1.5 mmol) Zn-Montmorillonite composite heated at 150°C in an air oven for about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube and stirring arrangement. The reaction was allowed to continue at room temperature for a period of 24 hours. About 99.5 % benzyl chloride was converted to the major product like diphenyl methane as analysed by Gas Liquid Chromatography and MASS spectra. Example 5: 0.62 g (1.5 mmol) Zn-ZnC12-Montmorillonite composite heated at 150°C in an air oven lor about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube and stirring arrangement. The reaction was allowed to continue at room temperature for a period of 24 hours. About 98 % benzyl chloride was converted to the major product like diphenyl methane as analysed by Gas Liquid Chromatography and MASS spectra. Example 6: 0.49 g (1.5 mmol) Cu-CuC12-Montmorillonite composite heated at 150°C in an air oven for about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube. The reaction was allowed to continue at room temperature for a period of 24 hours. About 25 % benzyl chloride was converted to the major product like diphenyl methane as analysed by Gas Liquid Chromatography and MASS spectra. Example 7: 0.45g (1.5 mmol) Ni-NiC12-Montmorillonite composite heated at 150°C in an air oven for about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube. The reaction was allowed to continue at room temperature for a period of 24 hours. About 10 % benzyl chloride was converted to the major product like diphenyl methane as analyzed by Gas Liquid Chromatography and MASS spectra. The main advantages of the present invention are : 1. The metal(ion)-clay composites can be prepared in a very pure state by a simple method and the composites after activation could be used as solid acid catalyst for organic synthesis. 2. Such products could maintain interlayer spacing in the range 2 to 4 A and thus may act size / shape selective catalysts. 3. The activity / efficacy can be enhanced further by well dispersing the metal salt under ultrasonic vibration over the surface of the metal(ion)-clay composites for generating intercalated as well as surface adsorbed active metal sites for using them as solid acid catalysts. 4. The products are stable up to about 350 ° C We Claim: 1. An improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) useful as solid acid catalysts , characterized in that intercalation of metal cations into the interlamellar spacing of Montmorillonite clay layer by the treatment of expandable Montmorillonite clay dispersed under ultrasonic vibration with metal salts (MX) where M = Zn, Cu, Ni, X = halide , which comprises treating 1% aqueous suspension of said expandable Montmorillonite clay dispersed under ultrasonic vibration with 1 molar, said metal salt for a period of 24 hours followed by dialysis to obtain a pure electrolyte free solid composite (Mn+ - Montmorillonite ), which is again dispersed in aqueous medium to make slurry and then treated with concentrated aqueous solution of 0.5 - 2.5 Molar metal salt (MX) where M = Zn, Cu, Ni, etc. X = halide; under ultrasonic vibration for a period of 1 hour and subsequently dried at about 80°C in air oven to obtain a homogeneous metal-metal salt-Montmorilonite composites which are finally activated in the temperature range 100° -300°C for a period 1 - 24 hours before using as solid acid catalysts. 2. An improved process as claimed in claim 1 wherein the metal ions in the metal-Montmorillonite composites is from any active metal ions from transition metal groups from the periodic table of elements. 3. An improved process as claimed in claims 1-2, wherein the metal ions in the metal-metal salt-Montmorillonite composites is same or different. 4. An improved process as claimed in claims 1-3, wherein the anion of the metal salt in the metal-metal salt-Montomorillonite composites is halide or any suitable anion. 5. An improved process for the preparation of intercalated clay composites useful as solid acid catalysts substantially as herein described with reference to the examples.

Full Text

The present invention relates to an improved process for the preparation of intercalated clay composites useful as solid acid catalysts.
The process of the present invention particularly relates to the preparation of intercalated clay composites by exchanging suitable metal cations with the exchangeable cations in the interlamellar spacing of expandable layered aluminosilicates (like smectite group clays). This invention is more particularly related to preparing efficient metal(cation)-metal salts - expandable clays (smectite, or the likes) composites useful as solid Bronsted and Lewis acid catalysts for alkylation reactions or the like organic reactions.
Supported inorganic reagents are rapidly emerging as a new and environmentally accepted materials for improving process efficiency or to replace environmentally unacceptable reagents and catalysts. Attempts are being made to replace highly corrosive HF in olefin alkylation, anhydrous A1C13 in Friedel Crafts alkylation etc. by supported
solid acid catalyst. All the solid acids are characterized by the presence of protons or coordinatively unsaturated cationic centers on the surface leading to Bronsted and Lewis acidity. Bronsted acidity comes from exchangeable cations which polarize interlayer water molecules. Partial dehydration increases the acidity. Replacement of the

exchangeable interlayer Na by high charge density cations such as Al , Zn etc. leads
to acidity as high as 10 mol dm . These highly acidic forms of Montmorillonite clays have been described as broad spectrum catalysts for organic synthesis. It is also important to note that at high temperatures clays are generally reduced to Lewis acidity only through the loss of interlayer water.

Swelling clays with layered structures offer the potential for shape selectivity although the interlayer gap in natural Montmorillonite can remain quite small.
The replacement of interlayer Na by cations as Fe , Al etc. leads to clay layers of high acidity and are described (J. A. Ballantine, J. H. Purnell and J. M. Thomes, J. Mol.
Cat., 27 (1984) 157) as broad spectrum catalysts for organic synthesis. Replacement of environmental unacceptable anhydrous A1C13 , an established catalyst for Friedel Crafts
alkylation, by supported A1C13 on K-10 montmorillonite has been claimed (J. H. Clark,
K. M. Andrew, A. J. Teasdale and S. J. Barlow, J. Chem. Soc. Chem. Com. (1995) 2037) to be an efficient catalyst. Anchoring of A1C13 on the hydroxy groups of the supporting
materials may occur (R. S. Drago and E. E. Getty, J. Am. Chem. Soc. 110 (1988) 3311) through the active group -O-A1C12. Smectite clays have been shown to be very effective
supports for a number of transitional metal salts. One such example is supported ZnCL -K-10-Montmorillonite clay which is prepared by digesting methanoic solution of ZnCL
with acid treated Montmorillonite(K-l0). When the loading is very high, the catalytic activity is low and this may be attributed to the aggregation of ZnCl2 on the support. The
metal salt is believed to stay as intact molecule residing within the pores of the support. Therefore, leaching of the metal salt from the support is very much likely and the catalytic activity is expected to be reduced accordingly. In order to overcome the narrow interlayer distance, a new class of pillared materials have been developed (D. E. W. Vaughan, R. T. Lussier and J. Magee (1979), US Patent No. 4176090) by exchanging

Na-montmorillonite with inorganic polyoxo metal ions like (Al13) of larger size and
charge and then calcining at about 450 °C for 4 hours. Metal ion exchanged catalysts were prepared (M. P. Atkins, Pillared layered structures, Current trend and application, Ed. I. V. Mitchell, Elsevier, Appl. Sc. (1990, 159) by treating the pillared clay with desired cations. The actual location of the cation exchange site in pillared clays is still not known. Such materials are also called "Pillared Clay" show higher interlayer spacing

(about 10-12 A). Despite their high thermal stability (> 5000 C) and high surface area (> 200 m2 /g), pillared clays are less efficient catalysts compared to cations (like Al ) exchanged clays.
The present invention is distinguished from the prior art in that it does not involve any acid treatment for modifying the solid matrix support of the Montmorillonite clay as used for generating Montmorillonite(K-l0). The present invention also does not involve high temperature for modifying the clay-support as required for developing "Pillared Clay" composites. The present process consists of simple two stage reaction steps; in the first step - the interlayer sodium (Na+) ions of the layered clay (Montmorillonite) are replaced by ion exchange with suitable metal ions (Mn+) like Ni, Cu, Zn etc. to produce homoionic intercalated Mn+- Montmorillonite layered composites followed by dialysis to purify the composite. In the second step - the pure Mn+- Montmorillonite is well dispersed into aqueous medium under ultrasonic vibration followed by treatment with calculated amount of metal salt (MX) where X = halide; to deposite as salt into interlayer spacing as well as on the surface of the layered Mn+-Montmorillonite to produce layered Mn+-MX-Montmorillonite composites which are activated in the temperature range 100 -300°C for 1-12 hours to generate a novel metal ion-metal salt active sites bearing layered clay composite for using as solid acid catalysts in organic synthesis.
These composites can behave as novel solid acid catalyst because they contain two different functional active metal sites i.e. one in the interlayer spacing of the clay and the other on the surface of the clay layers leading to simultaneous generation of two different acidic properties i.e. BrOnsted and Lewis acidity.
The main object of the present invention is to provide a process for preparing metal(cation)-metal salt-clay(expandable) composites useful as solid acid catalysts which obviates the draw back as described above.
Still another object of the present invention is to provide a simple process of preparing solid acids with BrOnsted and Lewis acid sites for catalysing organic reactions.

Accordingly the present invention provides, an improved process for the preparation of intercalated clay composites (metal-metal salt-Montmorilonite composites ) useful as solid acid catalysts , characterized in that intercalation of metal cations into the interlamellar spacing of Montmorillonite clay layer by the treatment of expandable Montmorillonite clay dispersed under ultrasonic vibration with metal salts (MX) where M = Zn, Cu, Ni, X = halide , which comprises treating 1% aqueous suspension said expandable Montmorillonite clay dispersed under ultrasonic vibration with 1 molar said metal salt for a period of about 24 hours followed by dialysis to obtain a pure electrolyte free solid composite (Mn+ -Montmorillonite ) which is again dispersed in aqueous medium to make slurry and then treated with concentrated aqueous solution of 0.5 - 2.5 Molar metal salt (MX) where M = Zn, Cu, Ni, etc. X = halide; under ultrasonic vibration for a period of 1 hour and subsequently dried at about 80°C in air oven to obtain a homogeneous metal-metal salt-Montmorilonite composites which are finally activated in the temperature range 100° - 300°C for a period 1-24 hours before using as solid acid catalysts.
In an embodiment of the present invention, the oxidic compositions of the montmorillonite clays of M/S Neelkanth Soda Clays & Pulveriser, Jodhpur, India and Na-montmorillonite, SWY-2, Wyoming, USA, after purification are shown (Table 1). Tablet. Chemical composition of clays:
(Table Removed)
The different process steps of the present invention are given below :
Purification of the clays (Montmorillonite):
The Bentonite powder (M/S Neelkanth) and Na-montmorillonite (Wyoming) were purified by standard gravity settling technique and the -2 (a. m fraction was collected in order to obtain the montmorillonite fraction. About 50 g of Bentonite powder or Na-montmorillonite clay was suspended in 1000 ml distilled water by stirring for half an hour and was set aside for about 24 hrs. The suspension upto 10 cm height from the top of the surface of the suspending liquid was collected for -2µ, m particle size. The mass was then dried above 50 ± 5° C in air oven. This fraction of the clay was rich in montmorillonite.
Conversion into Na-montmorillonite :
About 2 g of dry purified clay was suspended into 100 ml of distilled water and to it 100 ml of 2 M NaCl solution was added and kept stirring for about 12 hrs. The mass was allowed to settle and the supernatant liquid was decanted off. The slurry was again treated with NaCl solution and stirred. This step was repeated for about 4 times. The
excess NaCl was removed by washing with distilled water and finally dialysed till the conductivity of water is Oriented film was prepared from the dialysed Na-montmorillonite on glass slide by allowing about 1 ml suspension to dry at room temperature. The basal spacing (d001) as determined by XRD technique was found to be about 12 A for the room temperature dried sample. The slide was then kept in a desiccator over ethylene glycol for about 12 hrs. The d001 value obtained at 16.5 A indicated the identification of montmorillonite clay.
Cation Exchange Capacity (CEC) :
About 0.5 g of the clay was treated with alcoholic solution of CaC12 containing 4 Eqv.
CEC (considering 100 meq. / 100 g clay) and kept overnight under stirring condition.
++ The difference in the concentration of CaCl2 gave the amount of Ca exchanged. Then
about 0.5 g clay was treated with ammonium acetate solution containing about 4 Eqv. CEC. of the clay under stirring condition and the liberated CaCl2 was determined. From
these exchanged data, the total CEC was determined. The CEC determined for the M/S Neelkanth and Wyoming clays were 114 and 90 meq. /100 g of clay respectively.
Montmorillonite is composed of layered lattice structure and each sheet is composed of octahedral alumina sandwiched by two tetrahedral sheets of silica. The negative charge on the surface of these layers are, in general, developed by the isomorphous substitution
of alumina in octahedral layer by lower valent cations like magnesium or iron. These
negative charges are then counter balanced by exchangeable cations like Na , Ca , Mg
residing mostly in the interlayer space. These layered structures enable intercalation of other compounds of different characteristics between the sheets of the clay.
Adsorption of water expands the interlayer distance to a great extent (> 40 A). Upon heating at about 150° C, most of the interlayer water is lost and the layers of the clay approach closer to each other and leave very narrow interlayer space. The basal spacing i.e. the distance from the top of a layer to the top of the immediate layer, of
Na-exchanged montmorillonite dried at 110° C for 2 hrs., show a value of about 12 A . The basal spacing for a fully collapsed matrix is about 9. 6 A i.e. the layer thickness. Such composite materials are very much potent in respect of developing BrOnsted and Lewis acids. Bronsted acidity is generated by the polarizing power of the exchanged
cations i.e. Al , Zn ions. Such cations produce Bronsted acid strength by promoting a
reaction with water to release H ions -
[M(H20)x]+ H20 → [M(H20)x-l(OH)] As the clay surface loses moisture, the reaction is driven further to the right and the
protons are concentrated in a smaller volume of water. Air dried smectite with Al exchange ions are equivalent in acidities to concentrated aqueous solutions of strong acids. When the interlayer water is lost due to heating at higher temperature, the metal ion exchanged montmorillonite behaves as Lewis acids. Therefore, depending upon the water content of the composites, the nature as well as the strength of acidity depends. These types of acidity of the composites are useful as solid acid catalysts in organic synthesis.
The following examples are given by way of illustrations of the present invention and should not be construed to limit the scope of the invention.
Example 1 :
. 3.0 g of dried Na-montmorillonite clay (Wyoming) or Neelkantha Bentonite having size fraction of -2 µ m fraction was dispersed in about 300 ml of distilled water under constant stirring and then mixed thoroughly under ultrasonic vibration for about 10 min. To this homogeneous suspension. 25 ml solution containing 0.54g of NiCl2.6H20 was added slowly and stirred for, 24 hours and then dialysed till the solution was free from chloride. The mass was collected and dried at about 80 °C . About 1 gm of the Ni-Montmorillonite composite was dispersed in 100 ml of distilled water and stirred for about 2 hours and to this slurry 1.54 ml of 1(M) NiC12 solution was added drop wise and subjected to ultrasonic vibration for about 1 hour. The whole mass was then dried in an air oven at about 80 °C to obtain Ni-NiC12-Montmorillonite composite. The dried mass was then activated in the temperature range 100 to 300 °C for 1 to 24 hours before using as solid acid catalyst in organic synthesis like Friedel Crafts Reaction for alkylation of benzene.
Example 2 :
3.0 g of dried Na-montmorillonite clay (Wyoming) or Neelkantha Bentonite having size fraction of -2 µ m fraction was dispersed in about 300 ml of distilled water under constant stirring and then mixed thoroughly under ultrasonic vibration for about 10 min. To this homogeneous suspension. 25 ml solution containing 0.398g of CuC12.H2O was added slowly and stirred for . 24 hours and then dialysed till the solution was free from chloride. The mass was collected and dried at about 80 °C . About 1 gm of the Cu-Montmorillonite composite was dispersed in 100 ml of distilled water and stirred for about 2 hours and to this slurry 1.52 ml of 1 (M) CuC12 solution was added drop wise and subjected to ultrasonic vibration for about 1 hour. The whole mass was then dried in an air oven at about 80 °C to obtain Cu-CuC12-Montmorillonite composite. The dried mass.
was then activated in the temperature range 100 to 300 °C for 1 to 24 hours before using as solid acid catalyst in organic synthesis like Friedel Crafts Reaction for alkvlation of benzene.
Example 3 :
3.0 g of dried Na-montmorillonite clay (Wyoming) or Neelkantha Bentonite having size fraction of-2 µ m fraction was dispersed in about 300 ml of distilled water under constant stirring and then mixed thoroughly under ultrasonic vibration for about 10 min. To this homogeneous suspension, 25 ml solution containing 0.348g of ZnC12.2H2O was added slowly and stirred for about 24 hours and then dialyzed till the solution was free from chloride. The mass was collected and dried at about 80 °C . About 1 gm of the Zn-Montmorillonite composite was dispersed in 100 ml of distilled water stirred for about 2 hours and to this slurry 1.53 ml of 1(M) ZnC12 solution was added dropwise and stirred for about 24 hours. The whole mass was then dried in an air oven at about 80 °C to obtain Zn-ZnC12-Montmorillonite composite. The dried mass was then activated in the temperature range 100 to 300 °C for 1 to 24 hours before using as solid acid catalyst in organic synthesis like Friedel Crafts Reaction for alkvlation.
Example 4:
1.70 g (1.5 mmol) Zn-Montmorillonite composite heated at 150°C in an air oven for about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube and stirring arrangement. The reaction was allowed to continue at room temperature for a period of 24 hours. About 99.5 % benzyl chloride was converted to the major product like diphenyl methane as analysed by Gas Liquid Chromatography and MASS spectra.

Example 5:
0.62 g (1.5 mmol) Zn-ZnC12-Montmorillonite composite heated at 150°C in an air oven lor about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube and stirring arrangement. The reaction was allowed to continue at room temperature for a period of 24 hours. About 98 % benzyl chloride was converted to the major product like diphenyl methane as analysed by Gas Liquid Chromatography and MASS spectra.
Example 6:
0.49 g (1.5 mmol) Cu-CuC12-Montmorillonite composite heated at 150°C in an air oven for about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube. The reaction was allowed to continue at room temperature for a period of 24 hours. About 25 % benzyl chloride was converted to the major product like diphenyl methane as analysed by Gas Liquid Chromatography and MASS spectra.
Example 7:
0.45g (1.5 mmol) Ni-NiC12-Montmorillonite composite heated at 150°C in an air oven for about 12 hours and cooled in a desiccator to room temperature and then added to a mixture of 15 ml benzene (dried) and 1 ml benzyl chloride (dry) in a round bottom flask fitted with moisture arresting guard tube. The reaction was allowed to

continue at room temperature for a period of 24 hours. About 10 % benzyl chloride was converted to the major product like diphenyl methane as analyzed by Gas Liquid Chromatography and MASS spectra.
The main advantages of the present invention are :
1. The metal(ion)-clay composites can be prepared in a very pure state by a simple
method and the composites after activation could be used as solid acid catalyst for
organic synthesis.
2. Such products could maintain interlayer spacing in the range 2 to 4 A and thus may
act size / shape selective catalysts.
3. The activity / efficacy can be enhanced further by well dispersing the metal salt
under ultrasonic vibration over the surface of the metal(ion)-clay composites for
generating intercalated as well as surface adsorbed active metal sites for using them
as solid acid catalysts.
4. The products are stable up to about 350 ° C

We Claim:
1. An improved process for the preparation of intercalated clay
composites (metal-metal salt-Montmorilonite composites ) useful
as solid acid catalysts , characterized in that intercalation of
metal cations into the interlamellar spacing of Montmorillonite
clay layer by the treatment of expandable Montmorillonite clay
dispersed under ultrasonic vibration with metal salts (MX) where
M = Zn, Cu, Ni, X = halide , which comprises treating 1% aqueous suspension of said expandable Montmorillonite clay
dispersed under ultrasonic vibration with 1 molar, said metal salt for a period of 24 hours followed by dialysis to obtain a pure electrolyte free solid composite (Mn+ - Montmorillonite ), which is again dispersed in aqueous medium to make slurry and then treated with concentrated aqueous solution of 0.5 - 2.5 Molar metal salt (MX) where M = Zn, Cu, Ni, etc. X = halide; under ultrasonic vibration for a period of 1 hour and subsequently dried at about 80°C in air oven to obtain a homogeneous metal-metal salt-Montmorilonite composites which are finally activated in the temperature range 100° -300°C for a period 1 - 24 hours before using as solid acid catalysts.
2. An improved process as claimed in claim 1 wherein the metal
ions in the metal-Montmorillonite composites is from any active
metal ions from transition metal groups from the periodic table of elements.
3. An improved process as claimed in claims 1-2, wherein the
metal ions in the metal-metal salt-Montmorillonite composites is
same or different.
4. An improved process as claimed in claims 1-3, wherein the
anion of the metal salt in the metal-metal salt-Montomorillonite
composites is halide or any suitable anion.
5. An improved process for the preparation of intercalated clay
composites useful as solid acid catalysts substantially as herein
described with reference to the examples.

Documents:

207-del-2001-abstract.pdf

207-del-2001-claims.pdf

207-del-2001-correspondence-others.pdf

207-del-2001-correspondence-po.pdf

207-del-2001-description (complete).pdf

207-del-2001-form-1.pdf

207-del-2001-form-19.pdf

207-del-2001-form-2.pdf

207-del-2001-form-3.pdf

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Patent Number

231042

Indian Patent Application Number

207/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

27-Feb-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	DIPAK KUMAR DUTTA	REGIONAL RESEARCH LABORATORY, JORHAT-785006, ASSAM, INDIA.
2	ANJALI PHUKAN	REGIONAL RESEARCH LABORATORY, JORHAT-785006, ASSAM, INDIA.

PCT International Classification Number

B01J 04/06

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA