MONTMORJLLONITE CLAY" The following specifications particularly describe and ascertain the nature of the invention and the manner in which it is to be performed.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a process for reducing chloronitrobenzene catalyzed by platinum-nanoparticles stabilized on modified montmorillonite clay. The present invention more particularly relates to the preparation of Pt°-nanoparticles supported on modified montmorillonite clay, where the modification of the clay was carried out by activating with mineral acids such as HC1 under controlled conditions in order to generate nanopores in the range 0 to 8 nm for in-situ synthesis of Pt° nanoparticle. The invention still more particularly relates to an improved process for the selective reduction of chloronitrobenzenes to the corresponding chloroanilines catalysed by the environmentally benign and recyclable Pt°-nanoparticles supported on modified montmorillonite clay BACKGROUND AND PRIOR ART OF THE INVENTION

Aromatic haloamines are important class of industrial intermediate for the synthesis of organic fine chemicals, such as dyes, drugs, herbicides and pesticides. The main routes of synthesis of the haloamines involved reduction of corresponding nitrocompounds catalysed by either metal-acid systems or with noble metal. Processes involving later route are favored now a days due to environmental issues associated with the use of hydrochloric acid in the former route.

Control of selectivity is the critical problem while carrying out hydrogenation of halonitroaromatics with noble metal. Apart from the formation of halogenated aromatic amines, extensive dehalogention by cleaving the carbon-halogen bond also occurs. In addition, by-products such as azo and azoxyhalobenzenes are also formed. Furthermore, hydrogen chloride which is produced by the dehalogenation reaction greatly contributes to the corrosion of the reactor. Attempts were done to minimize the side reaction by the addition of selectivity promoters or dehalogenated inhibitor such as bases or other electron donating compounds along with noble metal catalyst. Numerous efforts (Greenfield et.al. J. Organic Chem., 1967, Vol. 32, Page 3670-3671) are being done to suppress the dehalogenation reaction and to minimize other by-products, including a method of using sulfides of noble metal as a catalyst and a method of adding dehalogenation inhibitor. Disadvantage of using noble metal sulphides is due to low catalytic activity and complicated preparation processes of these catalysts. In the US patent No. 4070401, Hirai and Miyata described a method for the preparation of a halogenated aromatic amine, wherein, a halogenated aromatic nitro compound is hydrogenated in liquid phase in the presence of a platinum-base catalyst to obtain a corresponding halogenated aromatic amine and the hydrogenation was carried out in the presence of an alkylmonoamine, an alicylic amine or a polyalkylenepolyamine. The main draw back of the process is that it takes longer reaction time i.e. 40 to 210 minutes depending upon the substrates and a pressure of about 50 kg/cm ² , although the conversion was 88.7 to 98.5%.

Reference may be made to the US patent No. 4375550, wherein the hydrogenation of halogen-substituted aromatic nitro compounds to corresponding amino compounds were carried out at elevated temperature (50 - 200°C) and pressure (1 - 70 atm) using catalysts consisted of platinum, palladium, rhodium, iridium, ruthenium and osmium supported on carbon material. The main draw back of the process is that it involves precious metals as well as the drastic process parameters.

In the US patent No. 4760187, Kosak disclosed a process of reducing chloro- nitrobenzenes to corresponding chloroanilines catalysed by metallic ruthenium- platinum at a pressure of 200 to 800 psi and temperature 70 to 160 °C. The products generated were contaminated with by-products and also prolonged reaction time was required for economical degree of conversion.

Reference may be made to the US patent No. 5068436, wherein, a process of reducing fluorinated or chloro-nitrobenzenes to corresponding haloanilines in presence of noble metals (such as rhodium, palladium, iridium, and platinum) supported on carbon / Raney nickel or cobalt catalyst in acidic catalytic medium. The process was associated with oressure 50 ta 7000 nsi t ^p m eratnr ^p tn 1 00 °C, time of reaction 1 to 2 h to yield greater than 99 %. The isolated yield was 80 to 90 %. The main draw back of the process was that it involved precious metals, complicated process parameters, higher reaction time and lower isolated yields.

Reference may be made to the US patent No. 5105011, wherein, a process was described for hydrogenation of halogenonitroaromatic compounds in the presence of a nickel-, cobalt- or iron-based catalyst preferably by Raney nickel and hydrogen in the presence of iodine at a temperature from 50 to 150°C and preferable pressure 1 to 100 bar. The main drawback of the process is that it involved some cumbersome steps, high pressure and a mixture of products were obtained.

Reference may be made to the US patent No. 5126485, wherein, a process was described for hydrogenation of halogenonitroaromatic compounds in the presence of a nickel-, cobalt- or iron-based catalyst preferably by Raney nickel and hydrogen in the presence of a sulfur-containing compound like sulfoxide or sulfone, at a temperature from 50 to 150 °C and preferable pressure 1 to 100 bar. The main drawback of the process is that it associated with some cumbersome steps, high pressure and a mixture of products were obtained.

In the US patent No. 7288500 B2, Liu et al., described a process wherein, hydrogenation of halonitroaromatic compounds was carried out in the presence of supported (carbon black, activated carbon, silica, alumina etc.) metals (palladium, platinum, ruthenium and rhodium) complexes of acetylacetone backbone ligands followed by reduction at temperature less than 160°C. The catalytic reduction was carried out at temperature 0 to 160°C, pressure 1 to 100 bar and reaction time 10.25 to 13.5 h to yield mixtures of compounds (selectivity 76 to 97 %). The main draw back of the process is that the process involved several complex steps of catalysts preparation and yields were impure products.

Reference may be made to the US patent No. 7381844, wherein, a process was described for hydrogenation of chlorinatednitrobenzene at temperature 40 to 150°C and pressure 5 to 40 atm in the presence of nanosized boron-containing nickel catalyst within a reaction time 10 to 80 minutes to give conversion 20 to 100 % and selectivity higher than 99 %. The main draw back of the process is that the process involved several complex steps of catalysts preparation and higher reaction time to yield higher selectivity. The Chinese patent CN101745382, discloses a catalyst for synthesizing parachloroaniline from parachloronitrobenzene by hydrogenation and a preparation method thereof. The active component of the catalyst is Pt, the carrier is attapulgite, and the content of the Pt is 0.1-5wt%. The catalyst not only has high activity, but also effectively inhibits the generation of a dechlorination reaction. Under the condition that the parachloronitrobenzene is completely transformed, the selectivity of 100% for the parachloroaniline is realized. The attapulgite clay with a mineral acid acidified (sulfuric acid or hydrochloric acid) to a concentration of 2 -10 wt%. Polyvinyl pyrrolidone and chloroplatinic acid-treated attapulgite was obtained after the acid solution was stirred at room temperature and dried to obtain a catalyst precursor. Finally, the catalyst precursor in a stream of hydrogen at 200 ~ 500 °C reduction of 2 to 10 h was used to obtain a catalyst by filtration, washing and drying procedure. The invention does not disclose about the particle size of the Pt catalyst nor disclose the surface area of the modified attapulgite matrix after acid modification. The overall process of the invention is cumbersome and lengthy.

Reference may be made to F. Wang et. al. Chem. Commun, (2008) 2040-2042, wherein, liquid phase hydrogenation of p-chloronitrobenzene in methanol was carried out at 40°C, ¾ pressure in the range 20 - 40 bar and time of reaction from 20 to 275 minutes in presence of polyvinylpyrrolidone protected platinum nanoparticles supported on layered zirconium phosphate in order to obtain conversion 74 to 100 % and selectivity 94 to 100 %. The main drawback of the above process is that it involves higher pressure and longer reaction time.

Zhang et. al. reported (J. Catalysis, 229, 2005, 1 14-1 18) that use of Pt/y-Fe ₂ 0 ₃ catalyst resulted about 100 % conversion of o-chloronitrobenzene to o-chloroaniline within 10 to 392 min with conversion 49 to 100 % and selectivity 45 to 99.9 %. The reaction was carried out in methanol at a temperature 60°C and pressure 10 to 40 bar. The main drawback of the process is that it involves considerably high pressure.

Reference may be made to Chang et. al., J. Colloid & In. Sc. 336 (2009) 675-678, wherein it was reported that platinum nanoparticles, immobilized in PEGs, catalyze hydrogenation of o-chloronitrobenzene with conversion 31 to 100 %, selectivity 84 to 99.7 %, within a reaction time from 30 to 600 min, Temperature 40 to 80°C and pressure 10 to 50 bar. The conversion and selectivity were lowered by the aggregation of Pt particles because the amount of PEG is not enough to protect platinum nanoparticles. Another drawback of the process is that the separation of catalyst from the reaction mixture is not simple.

Xiao et. al. reported (J. Catalysis, 250, 2007, 25-32) that use of platinum nanoparticles stabilized by ionic liquid like copolymer catalyst resulted in 77.5 to 95.9 % conversion of o-chloronitrobenzene to o-choloroaniline and 95.1 to 99.9 % selectivity within a period from 0.83 to 1 h. The reaction was carried out at a temperature of 60°C and 40 bar H ₂ pressure. The main drawback of the process is that it involves high pressure.

Reference may be made to Corma ^' . et. al. (J. Am. Chem. Soc. 130, 2008, 8748-8753), wherein hydrogenation of substituted nitroaromatics were carried by using platinum nanoparticles supported by Ti0 ₂ in tetrahydrofuran (THF) with 95 % selectivity within a period of 0.35 to 6.5 h. The reaction was carried out at temperature 45°C and 3 to 6 bar H ₂ pressure. Trie main drawback of the process is that it takes high time for the complete conversion.

Reference may be made to Liu et. al. (Synlett, 2009, 595-598) wherein, hydrogenation of o-chloronitrobenzene was carried out by using platinum nanoparticles supported carbon catalyst in ethanol with 100 % conversion and 66.5 to 99.4 % selectivity. The reaction was carried out at 25°C and 10 bar H ₂ pressure within 4.5 to 10 h. The main drawback is that the process is time consuming and selectivity is low.

Reference may be made to Motoyama et. al. (Organic Lett., 11, 2009, 1345-1348), wherein, the hydrogenation of m-chloronitrobenzene and o-chloronitrobenzene were carried out by polysiloxane gel encapsulated platinum nanoparticles in ethyl acetate with conversion in the range 63 to 99 %. The reaction was carried out at 25°C, 10 atm H ₂ pressure and for 24 h. The main drawback of the process is that it requires long time for the reaction.

Reference may be made to Dutta et al. (Synthesis and catalytic activity of Ni°-acid activated montmorillonite nanoparticles, Applied Clay Science 53, 2011, 650-656), wherein, the montmorillonite clay was modified by acid activation with mineral acid under controlled condition for generating nanoporous materials for using as support for Ni°-nanoparticles. The supported Ni°-nanoparticles showed efficient activity in transfer hydrogenation of acetophenone to 1 -phenyl ethanol with high very efficiency. OBJECTIVE OF THE INVENTION

The main objective of the present invention is to provide a process for reducing chloronitrobenzene catalyzed by platinum-nanoparticles stabilized on modified montmorillonite clay which obviates the drawbacks of the hitherto known prior arts. Another objective of the invention is to provide a process for preparation of chloroanilines from respective chloronitrobenzenes without cleaving of C-Cl bond giving about 100 % selectivity and leading to 100 % conversion within a minimum reaction time.

Another objective of the invention is the generation of Pt°-nanoparticles into the nanopores of the modified montmorillonite support by loading of H ₂ PtCl ₆ .6H ₂ 0 metal precursor followed by reduction with different reducing agents such as NaBH ₄ , ethylene glycol, hydrazine etc. under standard technique.

Still another object of the present invention is to provide a clean, consistently recyclable and robust catalyst for selective reduction of chloronitrobenzenes to the corresponding chloroanilines at comparatively lower pressure and lesser time.

SUMMARY OF THE INVENTION

The present invention provides a process for reducing chloronitrobenzene catalyzed by platinum-nanoparticles stabilized on modified montmorillonite clay wherein the said process comprises the steps of :

a) dissolving chloronitrobenzene in ethyl acetate in the mole ratio of 1 :50 to obtain a solution.

b) adding Pt°-nanoparticles stabilized on modified montmorillonite as catalyst such as herein described in the mole ratio of. 1 :82 with respect to chloronitrobenzene to the above said solution obtained in step a,

c) purging H ₂ gas for 5 min in the solution obtained in step b and then pressurizing with H ₂ gas in the range of 5-20 bar at room temperature;

d) heating the reaction mixture as obtained in step c to a temperature in the range of 40 to 50 °C for a period of 5-240 minutes at 500 rpm to obtain chloroaniline.

In another embodiment of the invention, modifying of the Na- montmorillonite was carried out with mineral acid (such as HC1 ) treatment and activating at about 80°C for 1 h in order to achieve desired pore size in the range 0-8 nm with an average pore diameter of about 4 nm and high surface area 578.5 m ² /g.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a process for reducing chloronitrobenzene catalyzed by Platinum-nanoparticles stabilized on modified montmorillonite clay which comprises contacting gaseous hydrogen with liquid reaction composition containing chloronitrobenzene and ethylacetate at a temperature around 45°C and at a pressure of 5-20 bar for a periods of 5-240 min in the presence of Pt°-nanoparticles catalyst prepared by successful loading of H ₂ PtCl ₆ .6H ₂ 0 metal precursor into the nanopores of modified montmorillonite clay by incipient wetness impregnation technique followed by reduction using different reducing agents.

In another embodiment of the invention, the selectivity to chloroanilines are higher than 99 % and conversion upto 100%.

In another embodiment of the invention, modifying of the Na- montmorillonite was carried out with mineral acid (such as HC1 ) treatment and activating at about 80°C for 1 h in order to achieve desired pore size in the range 0-8 nm with an average pore diameter of about 4 nm and high surface area 578.5 m ² /g.

In another embodiment of the invention, the platinum nanoparticles were prepared by impregnation of Η ₂ ΡίΟ ₆ .6Η ₂ 0 metal salt into the nanopores of modified montmorillonite clay by incipient wetness impregnation technique under vigorous stirring condition. The stirring was continued for 6h followed by evaporation to dryness in a rotary evaporator. The dry clay-H ₂ PtCl ₆ composite was dispersed in 50 ml ethylene glycol in a round bottom flask and was refluxed at 196°C for 6h under stirring condition. The products were recovered, washed with methanol until free from ethylene glycol and then dried at about 40°C for 12h.

In yet another embodiment of the invention, Pt°-nanoparticles stabilized on modified montmorillonite as catalyst is added in the mole ratio of 1 :82 with respect to chloronitrobenzene.

In another embodiment of the invention, hydrogenation reaction was carried out at a pressure in the range of 5-20 bar.

In another embodiment of present invention, wherein organic solvent used in hydrogenation reaction was ethyl acetate. In the present invention, the catalytic reaction was carried out in 50 ml autoclave equipped with temperature and pressure control. A typical hydrogenation reaction was carried out by dissolving 1 mmol. (157.5 mg) of chloronitrobenzene in ethyl acetate (5 ml) together with 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay and the reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with ¾ gas up to 5 - 20 bar at room temperature (25°C). The temperature of the reactor was raised to 45 ± 5°C. The reaction was allowed for 5 - 240 min. and the reaction mixtures were collected, the insoluble catalysts were recovered by simple filtration technique and the product was determined by gas chromatography.

In an embodiment of the invention, a process of purification of the mononmorillonite clay has been described as: about 60 g of montmorillonite clay (M/S Gujarat Mines Bentonite, Gujarat) exhibiting cation exchange capacity (CEC) 126 meq/100 g of clay determined by standard technique and evaluated by XRD as: Oriented Aims for the study were prepared from Na-montmorillonite on glass slides by allowing a few drops of suspension of the clay in water and then dried at room temperature. The basal spacings (d ₀₀₁ ) at room temperature as determined by XRD technique were found to around 12.5 A. The slide was kept over ethylene glycol in closed desiccator for about 24 h and the basal spacing (d ₀₀ i) was found to be 16.5 A characteristics for montmorillonite clay mineral was added under constant stirring to about 3000 ml distilled water in 5000 ml beaker and allowed to settle for about 20 h and the slurry collected from 18 cm from the top of the surface in order to collect less than 2 μιη fraction particle size. The collected clay was dried at 50 ± 5°C in air oven to get solid mass.

In another embodiment of the present invention, a process for conversion into Na- montmorillonite has been described as: about 2 g of dry purified montmorillonite clay was suspended in 100 ml of distilled water and to it 100 ml of 2M NaCl solution was added and kept stirring for about 2 h. The mass was allowed to settle and supernatant liquid was decanted off. The slurry was again treated with 2M NaCl solution and stirred. This step was repeated for about four times. The excess NaCl was removed by dialyzing the residue against distilled water till the conductivity of dialyzed approached that of distilled water and showed negative test for chloride ion with silver nitrate. The mass was then dried at 50 ± 5 ⁰ C in air oven. In another embodiment of the present invention, a process for preparation of acid activated montmorillonite has been described in order to prepare micro- (< 2 run) and mesoporous (2-50 run) aluminosilicates from montmorillonite clay minerals containing mainly octahedral and tetrahedral aluminium in the framework. The process comprises mixing the clay mineral with desired acid to leach substantially the octrahedral aluminium while leaving preferably the tetrahedral aluminium. The process has been described as: In a round bottom flask 5 g of montmorillonite clay was taken and to it 100 ml of 4M HC1 was added. The resulting dispersion was refluxed at about 100°C for a period of 1 h. After cooling down the mixture to room temperature, the slurry was filtered through Whatman 41 filter paper and the residue was washed with distilled water till it becomes acid free. The clay was then dried in air oven at 50 ± 5 °C over night to obtain the solid product. Yield 90.2 %

In still another embodiment of the present invention, a process has been described for preparation of porous materials with high surface area (BET) up to 578.5 m ² /g, pore volume 0.5965 cc/g and a pore diameter in the range 0-8 nm with an average pore diameter of 4.12 nm from montmorillonite clay by acid activation in order to use as solid support for generation of Pt°-nanoparticles.

The present invention also provides a method of generation of Pt°-nanoparticles as follows: 0.5 g of acid treated clay were taken in 100 ml round bottom flask to which 32 ml (0.02 M) aqueous solution of H ₂ PtCl ₆ .6H ₂ 0 were added slowly under vigorous stirring condition. The stirring was continued for another 10-12 h followed by evaporation to dryness in rotary evaporator. The dry clay-H ₂ PtCl6 composite were reduced with NaBH or Ethylene glycol or Sodium Citrate or Hydrazine or molecular Hydrogen by adopting standard methods. The products were recovered, washed and then dried at about 40°C for 12 h.

The size and morphology of Pt°-nanoparticles were characterized by TEM. It is evident from the TEM images that the average size distributions of Pt°-nanoparticles are in the range 0 - 10 nm. The micrographs clearly indicate that the particles have a spherical morphology and well dispersed on the support. Selected Area Electron Diffraction (SAED) pattern revealed the formation of hexagonal symmetry diffraction spot pattern indicating Pt°-nanoparticles were single crystalline in nature. The crystalline natures of the Pt°-nanoparticles were confirmed by the corresponding powder XRD pattern. The four sharp peaks of 20 value 39.9, 46.5, 68.3 and 81.5 degrees can be assigned to the (1 1 1), (200), (220) and (311) indices of face centered cubic (fee) lattice of Platinum. Average Particle size of the Pt°-nanoparticles prepared by using different reducing agents were calculated by using Scherfer equation and are given in Table 1. In order to ascertain the oxidation state, the samples were characterized by XPS analysis. The XPS spectra of Pt°-nanoparticles with two peak of binding energy 71.3 and 74.6 ev corresponding to Pt 4f _7/2 and 4f _5/2 levels confirm the presence of platinum in metallic state (zero oxidation state).

A Process Flow Diagram is given (below) to show the different major steps that are involved in the present invention.

Table 1: Surface Characterization of samples & Average Particle size calculated from Scherrer equation:

A Process Flow Diagram

(for the preparation of the Pt ⁰ -Nanoparticles-montmorillonite clay composites and their catalytic application in hydrogenation of chloronitrobenzene to chloroaniline)

Raw Bentonite Clay

(collected from Gujarat Mines, India)

Converted to Homoionic Sodium form

Acid (hydrocholoric / sulphuric acid) activation to

generate nanopores

Metal salt (chloroplatinic acid) impregnation on the acid activated

clay by Incipient Wetness technique

Reduction by any one of the agents: (i) Ethylene glycol, (ii) Sodium citrate, (iii) Hydrogen, (iv) Sodium tetraborohydrate and (v) Hydrazine) to generate Platinum Nanoparticles supported montmorilionite catalyst

Hydrogenation of chloronitrobenzene to chloroaniline in the presence of the EXAMPLES

The following examples are given by the way of illustration of the working of the invention in actual practice and therefore should not be constructed to limit the scope of the present invention.

Example 1:

0.5 g of acid activated montmorillonite were taken in 100 ml round bottom flask and 32 ml (0.02 M) aqueous solution of H ₂ PtCl ₆ .6H ₂ 0 were added slowly under vigorous stirring condition. The stirring was continued for another 10 h followed by evaporation to dryness in a rotary evaporator. The dry clay-H ₂ PtCl ₆ composite was dispersed in 50 ml ethylene glycol in a double necked round bottom flask and was refluxed at 196 °C for 6 h in nitrogen environment under stirring condition. The products were recovered, washed with methanol until free from ethylene glycol and then dried at about 40 °C for 12 h. yield about 90%. The resultant Pt°-nanoparticles exhibit surface area 262.86 m /g, specific pore volume 0.3277 cc/g and average pore diameter 4.98 nm.

Example 2:

0.5 g of acid activated montmorillonite were taken in 100 ml round bottom flask and 32 ml (0.02 M) aqueous solution of Η ₂ ΡίΟ ₆ .6Η ₂ 0 were added slowly under vigorous stirring condition. The stirring was continued for another 10 h followed by evaporation to dryness in a rotary evaporator. The dry clay-H ₂ PtCl ₆ composite was dispersed in 10 ml water and 0.38 mg NaBH (1 M) in 10 ml distilled water was added slowly over 15 min under constant stirring and the color was changed immediately from yellow to black. The mass was allowed to settle and washed with distilled water several times until the content was free of chloride ions and then dried at about 40 °C for 12 h. yield about 92 %. The resultant Pt°-nanoparticles exhibit surface area 159.95 m /g, specific pore volume 0.2279 cc/g and average pore diameter 5.70 nm. . Example 3:

0.5 g of acid activated montmorillonite were taken in 100 ml round bottom flask and 32 ml (0.02 M) aqueous solution of H ₂ PtCl ₆ .6H ₂ 0 were added slowly under vigorous stirring condition. The stirring was continued for another 10 h followed by evaporation to dryness in a rotary evaporator. The dry clay-H ₂ PtCl ₆ composite was dispersed in 10 ml water and 2.58 mg sodium citrate (1 M) in TO ml distilled water was added and refluxed at 80°C for 2 h under constant stirring. The resultant mass was allowed to settle and washed with distilled water several times and then dried at about 40°C for 12 h. yield about 95 %. The resultant Pt°-nanoparticles exhibit surface area 325.33 m ² /g, specific pore volume 0.41 10 cc/g and average pore diameter 5.05 nm.

Example 4:

0.5 g of acid activated montmorillonite were taken in 100 ml round bottom flask and 32 ml (0.02 M) aqueous solution of H ₂ PtCl ₆ .6H ₂ 0 were added slowly under vigorous stirring condition. The stirring was continued for another 10 h followed by evaporation to dryness in a rotary evaporator. The dry clay-H ₂ PtCl ₆ composite was dispersed in 10 ml water and 0.32 ml hydrazine (1 M) in 10 ml distilled water was added and stirred for 1 h under room temperature. The resultant mass was allowed to settle and washed with distilled water several times and then dried at about 40°C for 12 h. yield about 92 %. The resultant Pt°-nanoparticles exhibit surface area 160.77 m /g, specific pore volume 0.2006 cc/g and average pore diameter 4.99 nm.

Example 5:

0.5 g of acid activated montmorillonite were taken in 100 ml round bottom flask and 32 ml (0 .02 M) aqueous solution of H ₂ PtCl ₆ .6H ₂ 0 were added slowly under vigorous stirring condition. The stirring was continued for another 10 h followed by evaporation to dryness in a rotary evaporator. The dry clay-H ₂ PtCl ₆ composite was dispersed in 20 ml water in a 50 ml round bottom flask and H ₂ gas was introduced into the mixture through a balloon and the reaction mixture was kept under constant stirring. The resultant mass was allowed to settle and washed with distilled water several times and then dried at about 40°C for 12 h. yield about 96 %. The resultant Pt°-nanoparticles exhibit surface area 224.24 m ² /g, specific pore volume 0.2438 cc/g and average pore diameter 4.34 nm.

Example 6:

1 mmol (157.5 mg) of p-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by NaBH ₄ in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 5 bar at room temperature (25 °C). The reaction was carried out at temperature 50 °C for a period of 240 min at 500 rpm. After the catalytic reaction, the reaction mixtures were collected, the insoluble catalysts were recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 43 % and selectivity of the p-chloroaniline was 100%.

Example 7:

1 mmol (157.5 mg) of p-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by NaBH ₄ in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 45 °C for a period of 5 min at 500 rpm. After the catalytic reaction, the reaction mixtures were collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 74.6 % and selectivity of the p-chloroaniline was 97.7 %.

Example 8:

1 mmol (157.5 mg) of p-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by NaBH ₄ in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 40 °C for a period of 10 min at 500 rpm. After the catalytic reaction, the reaction mixtures were collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 94.3 % and selectivity of the p-chloroaniline was 97.1 %.

Example 9:

1 mmol (157.5 mg) of chloronitrobenzene (ortho and para) was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by NaBH ₄ in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25°C). The reaction was carried out at temperature 45°C for a period of 15 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion of o- chlorobenzene about 99.8 % and selectivity of the o-chloroaniline was 99.6 % and conversion of p-chlorobenzene about 98.3 % and selectivity of the p-chloroaniline was 99.0 %.

Example 10:

1 mmol (157.5 mg) of m-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by NaBH ₄ in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25°C). The reaction was carried out at temperature 45°C for a period of 30 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 99.3 % and selectivity of the m-chloroaniline was 99.9 %. Example 11:

1 mmol (157.5 mg) of p-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by NaBH ₄ in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with ¾ gas up to 20 bar at room temperature (25 °C). The reaction was carried out at temperature 45°C for a period of 15 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 97.8 % and selectivity of the p-chloroaniline was 97.5 %.

Example 12:

1 mmol (157.5 mg) of chloronitrobenzene (ortho and para) was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by hydrazine in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25°C). The reaction was carried out at temperature 45°C for a period of 15 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion of o- chlorobenzene about 100 % and selectivity of the o-chloroaniline was 99.6 % and conversion of p-chlorobenzene about 99.6 % and selectivity of the p-chloroaniline was 98.3 %.

Example 13:

1 mmol (157.5 mg) of m-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by hydrazine in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 45°C for a period of 30 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 98.9 % and selectivity of the m-chloroaniline was 99.7 %.

Example 14:

1 mmol (157.5 mg) of chloronitrobenzene (ortho and para) was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by ethylene glycol in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25°C). The reaction was carried out at temperature 45°C for a period of 15 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion of o-chlorobenzene about 99.7 % and selectivity of the o-chloroaniline was 99.9 % and conversion of p-chlorobenzene about 98.0 % and selectivity of the p-chloroaniline was 98.5 %.

Example 15:

1 mmol (157.5 mg) of m-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by ethylene glycol in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with ¾ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25°C). The reaction was carried out at temperature 45°C for a period of 30 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 99.9 % and selectivity of the m-chloroaniline was 95.3 %. Example 16:

lmmol (157.5 mg) of chloronitrobenzene (ortho and para) was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by hydrogen gas in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with ¾ gas up to 10 bar at room temperature (25°C). The reaction was carried out at temperature 45°C for a period of 15 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion of o-chlorobenzene about 99.7 % and selectivity of the o-chloroaniline was 99.7 % and conversion of p-chlorobenzene about 96.0 % and selectivity of the p-chloroaniline was 100 %.

Example 17:

1 mmol (157.5 mg) of m-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by hydrogen gas in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 45°C for a period of 30 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 100.0 % and selectivity of the m-chloroaniline was 99.6 %.

Example 18:

1 mmol (157.5 mg) of chloronitrobenzene (ortho and para) was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by sodium citrate in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 45 °C for a period of 60 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion of o-chlorobenzene about 99.9 % and selectivity of the o-chloroaniline was 99.5 % and conversion of p-chlorobenzene about 98.2 % and selectivity of the p-chloroaniline was 97.8 %.

Example 19:

1 mmol (157.5 mg) of m-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 16 mg of catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by sodium citrate in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with ¾ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 45 °C for a period of 90 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 99.9 % and selectivity of the m-chloroaniline was 99.7 %.

Example 20:

1 mmol (157.5 mg) of m-chloronitrobenzene was dissolved in ethyl acetate (5 ml) and added 1 1.2 mg of recycled catalyst containing Pt°-nanoparticles supported on modified montmorillonite clay reduced by hydrogen gas in a 50 ml hastelloy autoclave equipped with temperature and pressure control. The reaction vessel was purged with H ₂ gas for about 5 min and then pressurized with H ₂ gas up to 10 bar at room temperature (25 °C). The reaction was carried out at temperature 45 °C for a period of 15 min at 500 rpm. After the catalytic reaction, the reaction mixture was collected, the insoluble catalyst was recovered by simple filtration technique and the product was determined by gas chromatography. GC analysis showed conversion about 92.9 % and selectivity of the m-chloroaniline was 99.9 %. ADVANTAGES OF THE INVENTION

The main advantages of the present invention are:

1. A novel and eco-friendly prdcess for generation of Pt°-nanoparticles.

2. The montmorillonite was easily modified by activation with mineral acids under controlled condition for generating desired nanopores 0-8 ran.

3. The Pt°-nanoparticles (0-8 nm) generated into the nanopores of the modified montmorillonite clay were very stable and robust.

4. The hydrogenation reaction can be carried out at a temperature 45 °C and pressure 5 - 20 bar.

5. The present invention is distinguished from the prior art in that the process can yield high selectivity (>99 %) with conversion upto 100 % within a period of about 15 min.

6. The present invention utilizes a clean and inexpensive clay based solid support for generation of Pt°-nanoparticles in the size range 0-10 nm into the nanopores of the acid activated modified montmorillonite clay.

7. The present invention utilizes a reusable catalyst with good activity.

8. Separation of the catalyst from the reaction mixture is easy.