Title of Invention

"AN EFFICIENT CATALYST FOR THE CONTINUOUS REMOVAL OF CARBON MONOXIDE GAS AND THE PROCESS THEREOF"

Abstract

This disclosure provides the development of an excellent catalyst (palladium impregnated carbon system) to achieve continuous protection against carbon monoxide gas. The material was prepared by impregnating oxidized active carbon with palladium chloride using incipient wetness technique followed by liquid phase reduction to palladium. The developed material (6.5% Pd on carbon) was found to be working as a real turn over catalyst in oxidizing carbon monoxide to carbon dioxide and provided excellent protection against it. Increase in atmospheric moisture content (RH of air) enhanced the protection offered by the material. The shelf life of the material was also evaluated and found to be more than five years. This material/catalyst can be used in filtration systems such as CO canisters and filters to remove carbon monoxide gas.

Full Text

FIELD OF INVENTION The field of the invention is the area related to filtration of air to make it breathable. Air is the prime need of living beings on this planet and its purity is equally important as its availability. Various types of filtration systems are available in the market to get filtered air in toxic gases contaminated area. Toxic gases include organic/inorganic gases such as chemical warfare agents, vapors of organic solvents, sulfur dioxide, nitrogen oxides, carbon monoxide, etc. Carbon monoxide (CO), a hemo-toxic chemical hazard is produced due to incomplete combustion of articles. Fires in enclosed spaces (a ship hold), gunfire (generally with high explosives), products from flamethrower and engine exhaust (particularly when rich mixtures are employed), etc. may give rise to dangerous concentrations of CO gas. Therefore, there is a great concern among the scientists to have protection against deadly toxic CO gas. Protection against CO gas is the field of invention and it relates to the development of adsorbent/catalyst, i .e., Palladium impregnated carbon catalyst (Pd/C) for the reactive removal of carbon monoxide gas. This system works as a real turn over catalyst and provides endless protection against deadly toxic carbon monoxide gas under ambient conditions by oxidizing it. Shelf life of Pd/C was found to be more than five years. This material (Pd/C) can effectively be used in filtration systems such as submarine filters and canisters for individual protection against CO gas in enclosed areas such as coal mines and during firing accidents. PRIOR ART During World War I the subject of protection against CO gas was investigated very widely. As CO gas is very light than air, direct adsorption is apparently out of question. Permanent bonding of CO with hemoglobin indicates that synthetic analogue of hemoglobin may be a suitable material, if it could be prepared. Direct blood is of no use. Summary and Technical report of the National Defence Research Committee, Division 10, 1(1) 1946,Washington DC, entitled as, Military problems with aerosols and non-persistent gases, by Noyes WA Jr. indicated the use of several compounds (hoolamite (I2O5 + fuming H2SO4), silver permaganate, Hopcalite, etc.) as a catalyst for oxidizing carbon monoxide into carbon dioxide at ambient temperature. Hopcalite which predominantly comprised of copper oxide and manganese oxide was the most successful catalyst and still is in use as a universal and standard material for CO canister. Patents in which the use of hopcalite has been highlighted for the removal of CO gas are U.S. Pat. No. 5,038,768 entitled as carbon monoxide conversion device and U. S. Pat. No. 4,925,631 entitled as method of casting a hopcalite filter and cast ceramic fiber-hopcalite. The hopcalite is a moisture sensitive catalyst and its catalytic activity is greatly reduced due to the presence of moisture in air. To save hopcalite from moisture the CO canister contains the desiccant layer/bed, which absorbs the moisture of the inlet CO contaminated air. Bigger CO filtration systems other than canister utilize the parallel air-drying systems. U.S. Patent No 4,054,428 entitled as method and apparatus for removing carbon monoxide from compressed air utilizes the cyclic parallel desiccant air drying system installed upstream of the catalyst bed (hopcalite) to reduce the moisture content of the air. The efficiency and service life of hopcalite based CO canister mainly depends on the desiccant layer, i. e ., as soon as the desiccant is saturated with moisture, it allows the moisture to come in contact with hopcalite layer and deactivates it. Therefore, the main disadvantage associated with hopcalite is it's poisoning due to water, which makes it to be unsuitable for longer durations or under humid conditions. Yet another disadvantage of hopcalite is its lesser shelf life and limited protection against CO gas. In last few years various catalysts based on Cu(I) acetylacetone complexes (U.S. Pat. No. 4,279,874), gold, palladium [J. Catal . 41(1976) 397-404,1 Am. Chem. Soc. 123(2001)1166, etc] were also prepared and their activity has been determined against CO gas. A noble metal catalyst such as platinum and palladium exhibits improved catalytic activity in the oxidation of carbon monoxide provided that the catalyst is supported by a carrier having a relatively large specific surface area such as alumina, silica, silica-alumina or diatomaceous earth. However, the level of catalytic activity is not sufficient at an ambient temperature, although it increases substantially at 50 to 70°C or higher. Palladium impregnated kaolin based adsorbent system is also available but suffers from the fact of less protection against CO gas under humid conditions. Above discussed system also suffer from the fact that they cannot be regenerated for further use. By considering the above-discussed factors we have already developed the palladium impregnated carbon catalyst for the removal of CO gas, which was proven to be the best material for CO removal. This work has already been filed for Indian Patent Application no. 2409/DEL/2006. But in the present invention we have further improved the catalyst manufacturing process. Accordingly, the objectives of the present invention are to eliminate the above-mentioned disadvantages of the prior arts and to provide an improved catalytic material, which is capable of converting carbon monoxide to carbon dioxide continuously for longer durations under ambient conditions of temperature & relative humidity and can be regenerated. NEED FOR THE PRESENT INVENTION Imported filters are currently in use for the removal of CO gas. These filters are very costly and provide limited protection against CO gas. These filters also do not work properly under humid conditions. Therefore, it was the need of hour to develop the indigenous adsorbent material, which can be used in CO filters to remove CO gas catalytically and continuously under ambient conditions of temperature and humidity. OBJECTIVE OF PRESENT INVENTION. The primary objective of the present invention was to prepare a Pd impregnated carbon catalyst to remove CO gas. Another objective was to modify the earlier catalyst manufacturing process [Indian Patent Application no 2409/DEL/2006], which can provide more catalytic efficiency(at least three fold increase). Still another objective was to develop the catalyst based on coconut shell carbon. Yet another objective was to develop a process to prepare the catalyst, based on incipient wetness technique followed by liquid phase reduction. Further objective was to develop the adsorbent material ,which remains effective under humid conditions. Still another objective was to develop adsorbent, which can work in a catalytic manner to remove CO gas. Still another objective was to develop the cheaper adsorbent material. Further objective was to develop the adsorbent material having high shelf life. Yet another objective was to develop the adsorbent material, which can be regenerated at very low cost if its efficiency is over. BRIEF DESCRIPTION OF FIGURES Figure 1 shows the test rig used for the evaluation of prepared systems (Pd/C) against carbon monoxide gas. Figure 2 shows the probable mechanism of conversion of carbon monoxide to carbon dioxide in presence of atmospheric moisture over Pd/C. It also indicates the regeneration of the material. SUMMARY OF INVENTION Palladium impregnated carbon system, as a catalyst/filtration material is the solution for the above-mentioned problem, i. e., protection against deadly toxic CO gas. It provides excellent protection against hemotoxic CO gas under ambient conditions and works as a real turn over catalyst. DETAILED DESCRIPTION OF THE INVENTION Pd/C catalyst system is an excellent system for removal of CO gas. Besides being efficient in selectively removing the CO gas from air,it is also advantageous as it gets regenerated. The palladium impregnated carbon catalyst for the removal of CO gas has already been developed by us. This work has already been filed for Indian Patent Application no. 2409/DEL/2006. But in the present invention efforts have been made to further improve the catalyst manufacturing process. So produced catalyst has been compared with the earlier developed catalyst and found to be much better. Preparation of Pd/C catalyst In general, for the synthesis of palladium impregnated carbon system, firstly the base carbon was acidified with nitric acid to generate acidic functional groups over carbon surface. Then a known weight of so produced acidic groups functionalised carbon was then impregnated with acidic solution of palladium chloride, followed by neutralization with the impregnation of sodium hydroxide. So produced palladium chloride impregnated carbon was then subjected to liquid phase reduction to highly dispersed palladium on carbon surface. Reduction was performed using formaldehyde and sodium hydroxide with constant stirring. Finally the Pd/C material was filtered, washed with distilled water, dried in stainless steel (SS) tray dried at 110°C for over night and stored thus dried Pd/C in airtight bottles till use. Using the same preparation method palladium impregnated carbon system (Pd/C) with various palladium percentages (1.0-10. 0% Pd w/W) was prepared. In order to prepare 1.0-10. 0% palladium containing Pd/C catalyst system, coconut shell based granular activated carbon, grade 60 to 90 carbon tetrachloride (CTC) (preferably 90 CTC), particle size 18 X 40 British Sieve Size (BSS) (preferably 12 X 30 BSS) and BET surface area 1000 to 1500 m2/g (preferably 1350 m2/g) was taken. General Preparation of Pd/C containing 1.0-10.0% palladium Initially 100 g of granular activated carbon was allowed to react with 8-14%( preferably 10%) nitric acid such that the ratio of C : HNO3 = 1:4 to 1:6 (w/v) i . e. 400 to 600 ml (preferably 500 ml), at 50 to 80°C (preferably 60°C) for 5 to 10 hours, preferably 8 hrs to generate acidic surface functional groups. After acid treatment the carbon was washed with deionized water till it became neutral (pH~7). Finally it was dried in an SS tray at 100 to 120°C (preferably at 110°C) for 3 to 6 hrs (preferably 4 hrs), cooled in a desiccator and kept in airtight bottles for further processing. Thus produced 100.0 g of acidic group functionalised carbon was impregnated with a solution of 1.078 to 18.522g of palladium chloride(as per required percentage of impregnation) in 1.71 to 18.52 ml of concentrated hydrochloric acid with a total volume of 80 mL made by pouring distilled water i. e., 1000 ml of acidic solution of palladium chloride comprises of 21.35 to 231.5 g of palladium chloride and 21.3 to 231.5 ml of hydrochloric acid. Incipient wetness technique was used for the impregnation of palladium chloride on carbon. The carbon was impregnated with palladium chloride using the solution of palladium chloride followed by drying in SS tray driers at 100 to 120°C preferably 110°C for 6 hrs. The volume of the acidic solution of palladium chloride is just sufficient to wet the adsorbent particles so as to avoid aggregation of particles preferably from 50 to 80 ml for each 100 g of carbon. Thus produced palladium chloride impregnated carbon was neutralized with 2.1 to 32.5 g of sodium hydroxide in 105 ml of distilled water i.e., 20 to 310 g of sodium hydroxide per liter of solution, using incipient wetness technique .For neutralization of carbon, it was impregnated with sodium hydroxide solution followed by drying in SS tray driers at 100 to 120°C preferably 110°C for 6 hours. The volume of the sodium hydroxide solution is just sufficient to wet the adsorbent particles so as to avoid aggregation of particles preferably from 50 to 80 ml for each 100 g of carbon. For the synthesis of palladium impregnated carbon system with more palladium percentage (>7.0%) two stage impregnation of palladium chloride or sodium hydroxide can be adopted using the impregnation volume from 50 to 80ml for 100 g of activated carbon each for palladium chloride and sodium hydroxide impregnations respectively, in first stage and remaining solution in second stage i.e., the ratio of activated carbon to acidic solution of palladium chloride or sodium hydroxide solution is 10:7 to 10:8 for first stage and for second stage the said ratio is from 10:5 to 10:6. Thus produced neutralized palladium impregnated carbon is subjected to liquid phase reduction by pouring it into sodium hydroxide solution prepared by diluting 20-40% preferably 30% aqueous sodium hydroxide with distilled water and adding formaldehyde into the reaction mixture followed by filtering washing and drying to obtain palladium impregnated carbon catalyst. The neutralized palladium chloride impregnated carbon obtained from 100 g of activated carbon was poured to the beaker/reactor having 1500 ml distilled water with 2 to 20 ml of 30% sodium hydroxide solution heated to a temperature of 70-90°C preferably 80°C. This was continuously stirred and 20 to 160 ml of 37% formaldehyde solution was added to it. The pH of the solution was continuously checked and was maintained between 8 to 10 gradually adding more 30% aqueous sodium hydroxide solution, if required. The suspension was continuously stirred for 1 to 2 hrs and maintained between 70 to 90°C preferably 80°C. The material was then filtered and washed at least 6 preferably 6 to 10 times with 2000 to 5000 ml portions of hot distilled water. The material was dried in SS tray driers at 100-120°C preferably 110°C and finally stored in air tight bottles. Using the above given procedure the Pd/C material with 1.0 to 10.0 % Pd can be prepared, however, the procedure for the preparation of 4.0, 6.5 and 8.0% palladium impregnated Pd/C catalyst is given under examples. The shelf life of the catalyst material (6.5% Pd/C), already discussed in our earlier Indian patent application No. 2409/DEL/2006 was found to be 5 years. As Pd/C is a costly material, therefore, the suitability of the material for its regeneration capability has already been explored and declared that the catalyst can suitably be regenerated. Figure 2 describes the probable mechanism for the catalytic conversion of CO to CO2over the surface of palladium impregnated carbon system and regeneration of the catalyst material by atmospheric water. Pd/C system initially adsorbs CO gas than it converts CO to CO2in the presence of oxygen gas. So produced carbon dioxide gas remains on the surface of Pd/C and poisons the catalytic efficiency of the material via getting adsorbed at palladium active sites. This does not allow the material to adsorb CO gas and CO breaks through very fast. If atmospheric air is used with CO gas then atmospheric water molecules regenerate the catalyst by removing the adsorbed CO2 gas molecules. In that fashion the catalyst (Pd/C) provides endless protection against CO gas. This quality of regeneration of the catalyst makes Pd/C system to be the best one for CO gas removal at ambient conditions of temperature and humidity. Therefore, it can be concluded that the 6.5% palladium impregnated carbon based catalytic system is sufficient enough to provide protection against CO gas for longer duration under the set of given conditions, however, the material provided three fold more protection than the catalyst made by old method as in Indian Patent Application no. 2409/DEL/2006 . The developed material can potentially be used in submarine filters for protection against CO gas. This catalyst material can also be used in canisters for individual protection against CO gas in enclosed areas such as coal mines and during firing accidents. Examples The process for the preparation of palladium impregnated carbon has been described as above will be further understood with reference to the following non-limiting examples. Example 1: Preparation of 4.0% Pd/C:- In order to prepare 4.0% Pd/C system, 100.0 g of acidic group functionalised carbon was impregnated with a solution of 6.95g of palladium chloride(as per required percentage of impregnation) in 7.0 ml of concentrated hydrochloric acid with a total volume of 80 ml made by pouring distilled water. Incipient wetness technique was used for the impregnation of palladium chloride on carbon. 80 ml of acidic palladium chloride solution was taken for the impregnation of the carbon. This was followed by the drying of the material in SS tray driers at 110°C for 6 hrs. Thus produced material was neutralized with 8.5 g of sodium hydroxide in 105 ml of distilled water using incipient wetness technique 105ml of solution was taken for the impregnation of the carbon. This was followed by the drying of the material in SS tray driers at 110°C for 6 hrs. Thus produced material was poured to the beaker having 80°C heated 1500 ml distilled water with 8.0 ml of 30% sodium hydroxide solution. This was continuously stirred and 70 ml of 37% formaldehyde solution was added to it. The solution was continuously checked for its alkalinity (8-10 pH) and maintained at the same pH by adding a few drops of 30% aqueous sodium hydroxide solution, if required. The suspension was continuously stirred for 1 hrs and maintained at 80°C. The material was then filtered and washed hot at least 10 times using 3000 ml portions of distilled water. The material was dried in SS tray driers at 110°C for 6 hrs and finally stored in airtight bottles. Example 2 : Preparation of 6.5% Pd/C :- In order to prepare 6.5% Pd/C system, 100.0 g of acidic group functionalised carbon was impregnated with a solution of 11.6 g of palladium chloride (as per required percentage of impregnation) in 11.6 ml of concentrated hydrochloric acid with a total volume of 80 ml made by pouring distilled water. Incipient wetness technique was used for the impregnation of palladium chloride on carbon. This was followed by the drying of the material in SS tray driers at 110°C for 6 hrs. Thus produced material was poured to the beaker having 80°C heated 1500 ml distilled water with 13.0 ml of 30% sodium hydroxide solution. This was continuously stirred and 105 ml of 37% formaldehyde solution was added to it. The solution was continuously checked for its alkalinity(8-10 pH) and maintained at the same pH by adding a few drops of 30% aqueous sodium hydroxide solution, if required. The suspension was continuously stirred for 2 hrs and maintained at 80°C. The material was then filtered and washed hot at least 10 times using 4000 ml portions of distilled water. The material was dried in SS tray driers at 110°C and finally stored in airtight bottles. Example no.3 : Preparation of 8.0% Pd/C :- In order to prepare 8.0% Pd/C system, 100.0 g of acidic group functionalized carbon was impregnated in two stages with a solution of 14.6 g of palladium chloride (as per required percentage of impregnation) in 14.6 ml of concentrated hydrochloric acid with a total volume of 130 ml made by pouring distilled water. Incipient wetness technique was used for the impregnation of palladium chloride on carbon. In first stage 70 ml of acidic palladium chloride solution was taken for the impregnation of the carbon. This was followed by the drying of the material in SS tray driers at 110°C for 4 hrs. After that the carbon was impregnated for second stage impregnation with the remaining solution of palladium chloride followed by again drying in SS tray driers at 110°C for 4 hrs. Thus produced material was neutralized in two stages with 17.5 g of sodium hydroxide in 125 ml of distilled water using incipient wetness technique. In the first stage 70mL of solution was taken for the impregnation of the carbon. This was followed by the drying of the material in SS tray driers at 110°C for 6 hrs. After that the carbon was impregnated for second stage impregnation with the remaining solution followed by again drying in SS tray driers at 110°C for 6 hrs. Thus produced material was poured to the beaker having 80°C heated 1500 ml distilled water with 16.0 ml of 30% sodium hydroxide solution. This was continuously stirred and 130 ml of 37% formaldehyde solution was added to it. The solution was continuously checked for its alkalinity(8-10 pH) and maintained at the same pH by adding a few drops of 30% aqueous sodium hydroxide solution, if required. The suspension was continuously stirred for 40 minutes and maintained at 80°C. The material was then filtered and washed hot at least 10 times using 3000 ml portions of water. The material was dried in SS tray driers at 100°C and finally stored in airtight bottles. Example no 4 : A test-rig is used to generate CO- air mixture of different concentrations and to determine the efficiency of prepared Pd/C system against CO gas Test - rig for the catalytic removal of CO gas over Pd/C material/Catalyst: Figure 1 shows the test-rig used to generate CO- air mixture of different concentrations and to determine the efficiency of prepared Pd/C system against CO gas. For this, CO from CO cylinder (l),air using ambient air pump (3) and flow meters (2) was mixed in mixing chamber (4). The concentration of CO- air mixture was determined by passing it to CO detector (8). CO-air mixture was then passed through the Pd/C column (6) using two-way control valve (5) and the breakthrough time was monitored by passing the filtered air from column out-let to the CO detector. Carbon column diameter, bed height and CO air mixture flow rate was same as mentioned in Indian Patent Application no. 2409/DEL/2006, however, the catalyst was also tested at higher flow rates and higher concentrations of CO gas. Following were the experimental conditions :- carbon column bed height : 5.0 cm carbon column diameter : 2.0 cm CO-ambient air mixture flow rate : 4.5 1pm CO inlet concentration : 131 ppm (150mg/M3) breakthrough time(btt) observation at : 13 ppm (15mg/M3) Temperature/Relative humidity : Ambient, i. e., temperature 30 ± 1 c and Rh 50 ± 5% In our earlier filed Indian patent application no 2409/DEL/2006, it was concluded that Pd/C system containing Pd > 6.0 % is efficient for CO gas removal. However , on safer side it was declared that 6.5 % palladium impregnated carbon catalyst is the optimized one for continuously removing CO gas under the set of given conditions. The catalyst (6.5 % Pd/C) made by old method also provided the required protection even if the concentration is increased to three times, i. e., 393 ppm,however, it could not provide desired protection at 665 ppm of CO gas inlet concentration. Therefore , a comparison of 6.5% Pd/C prepared with old method and new modified method and new modified method is being discussed over here. Table 1 describes the comparative breakthrough behavior for CO gas with respect to the materials prepared with old and new modified method. Table 1 indicates that 6.5 % Pd/C made by old method could provide 100 % protection against CO gas @ of 131 ppm of CO inlet concentration, however as per required protection limit, i. e. 13 ppm the catalyst also provided protection @ 262 and 393 ppm [as at 60 minutes the outlet concentration of CO gas is 12 ppm only,which is less than 13 ppm (allowed limit)] of CO inlet concentration. Catalyst manufactured by old method showed less protection at 665 ppm of CO inlet concentration and indicated 80 ppm as outlet concentration Table 2 describes the effect of CO concentration on breakthrough behavior with these systems. In order to increase the CO concentration and maintain the same flow rate of CO - air mixture the flow meters of CO cylinder and ambient air were adjusted accordingly. Table 2 indicates that 6.5% palladium impregnated carbon catalyst did not show any breakthrough of CO gas if the concentration is increased to 1310 ppm. But at 1500 ppm the btt value was even lesser than 5 minutes. Table 2 also indicates that the outlet concentration of CO gas was progressively increasing with an increase in inlet concentration. As the catalyst is providing 100 protection against 1310 ppm of CO gas, therefore, be on safer side, it can be declared that the new manufacturing method is an excellent method for the synthesis of palladium impregnated carbon catalyst and the prepared catalyst provides 100% protection against 1000 ppm of CO inlet concentration. Example no.5 The effect of humidity on 6.5 % Pd/C catalytic system was also explored for CO removal efficiency. For that air for the dilution of CO gas was taken from air cylinder having nil moisture content the protection behavior against CO gas was very interesting. The protection efficiency decreased . When the atmospheric air was taken for dilution the efficiency increased. However, the same was also found when the air was taken for dilution the efficiency increased. However, the same was also found when the air for dilution was passed through water column, which increased the RH to >90% and decreased the outlet CO concentration considerably. It high lightened the necessity of moisture for the effective removal of CO gas. Example no. 6 In order to confirm the necessity of moisture more experiments were conducted. At 1500 ppm of CO inlet concentration 6.5 % Pd/C indicated 102 ppm CO outlet concentration at 15 minutes. Then the air from ambient air pump was passed through water bubbler, which increased the RH to > 90 % . The CO outlet concentration of CO gas started coming down and within 10 minutes it reached to nil. This indicated the importance of moisture for the material to work excellently against CO gas removal. Table 1 comparative breakthrough behavior for CO gas with respect to the materials prepared with old and new modified method. (Table Removed) Table 2 CO breakthrough behavior of 6.5 % Pd/C prepared using new method at different CO inlet concenrations. (Table Removed) WE CLAIM: 1. A process for the preparation of palladium impregnated carbon catalyst for removal of carbon monoxide gas, the said process comprising the steps of: a. reacting activated carbon with nitric acid to generate acidic functional groups over carbon surface, followed by washing and drying to obtain acidic group functionalised carbon; b. impregnating so produced acidic group functionalised carbon of step a with acidic solution of palladium chloride through incipient wetness technique to obtain palladium chloride impregnated carbon; c. neutralizing the palladium chloride impregnated carbon as produced in step b with sodium hydroxide using incipient wetness technique to obtain neutralized palladium chloride impregnated carbon; and d. subjecting neutralized palladium chloride impregnated carbon as produced in step c to liquid phase reduction by pouring it into sodium hydroxide solution, adding formaldehyde into the reaction mixture, followed by filtering, washing and drying to get palladium impregnated carbon catalyst. 2. The process as claimed in claim 1, wherein the activated carbon used for preparation is coconut shell based of the grade 60 to 90 carbon tetrachloride having particle size 18 X 40 British Sieve Size and BET surface area 1000 to 1500m2/g. 3. The process as claimed in claim 1, wherein in step a said acidic group functionalised carbon is obtained by reacting activated carbon with 8-14 percent nitric acid in the ratio of 1:4 to 1:6 (w/v) for 5- 10 hours preferably 8 hours at the temperature in the range of 50 to 80 degree Celsius, preferably 60 degree Celsius to generate acidic functional groups over carbon surface, followed by washing with deionized water and drying at 100 to 120 degree Celsius preferably 110 degree Celsius for a period of 3 to 6 hours preferably 4 hours followed by cooling in a desiccator to obtain acidic group functionalised carbon. 4. The process as claimed in claim 1 wherein said acidic solution of palladium chloride is obtained by adding concentrated hydrochloric acid to palladium chloride and diluting with distilled water such that the acidic solution of palladium chloride comprises of 21.3 to 231.5 g of palladium chloride and 21.3 -231.5 ml of hydrochloric acid per liter of the solution. 5. The process as claimed in claim 1, wherein for said impregnation of carbon with palladium chloride through incipient wetness technique in step b, the volume of the acidic solution of palladium chloride is just sufficient to wet the adsorbent particles so as to avoid aggregation of particles, preferably from 50 - 80 ml for each 100 g of carbon followed by drying at the temperature in the range of 100 to 120 degree Celsius preferably 110 degree Celsius for 6 hrs before subjecting to step c. 6. The process as claimed in claim 1, wherein for said neutralization of palladium chloride impregnated carbon through incipient wetness technique in step c , the sodium hydroxide solution comprises of 20 - 310 g of sodium hydroxide per liter of the solution and its volume is just sufficient to wet the adsorbent particles so as to avoid aggregation of particles, preferably 50 to 80 ml for each 100 g of carbon. 7. The process as claimed in claim 1, wherein in step d, said sodium hydroxide used has a concentration of 20 to 40 % preferably 30% diluted by adding distilled water to make a total volume of 1500 ml for each 100 g of activated carbon, to the said solution 20 to 160 ml of 37% formaldehyde solution is added while maintaining the pH of the solution in the range of 8 to 10 and temperature at 70 to 90°C preferably 80°C and continuing the reaction for 1 to 2 hrs. 8. The process as claimed in claim 7, wherein after said liquid phase reduction in step d the palladium impregnated carbon so produced is washed at least 6 preferably 6 to 10 times with portions of hot distilled water in the ratio of 1:20 to l:50(w/v). 9. The process as claimed in claim 1, wherein for preparation of palladium impregnated carbon catalyst with more than 7% palladium the impregnation of activated carbon with palladium chloride in step b and neutralization of palladium chloride impregnated carbon in step c is done in two stages, where in the first stage the ratio of activated carbon to acidic solution of palladium chloride or activated carbon to sodium hydroxide solution is 10:7 to 10:8 (w/v) and in the second stage said ratio is from 10:5 to 10:6 (w/v). 10. Palladium impregnated carbon catalyst as produced by reacting activated carbon with nitric acid to generate acidic functional groups over carbon surface,followed by washing and drying to obtain acidic group functionalised carbon; impregnating so produced acidic group functionalised carbon with acidic solution of palladium chloride through incipient wetness technique to obtain palladium chloride impregnated carbon; neutralizing the palladium chloride impregnated carbon with sodium hydroxide using incipient wetness technique to obtain neutralized palladium chloride impregnated carbon; and subjecting neutralized palladium chloride impregnated carbon so produced to liquid phase reduction by pouring it into sodium hydroxide solution , adding formaldehyde into the reaction mixture , followed by filtering, washing and drying to get the palladium impregnated carbon. 11. A process for the preparation of palladium impregnated carbon catalyst, substantially as herein described with reference to the foregoing examples and accompanying drawings. 12. Palladium impregnated carbon catalyst, substantially as herein described with reference to the foregoing examples and accompanying drawings.

Documents:

2130-del-2007-abstract.pdf

2130-del-2007-Claims-(22-05-2013).pdf

2130-del-2007-claims.pdf

2130-del-2007-Correspondence Others-(04-09-2008).pdf

2130-del-2007-Correspondence Others-(22-05-2013).pdf

2130-del-2007-correspondence-others.pdf

2130-del-2007-description (complete).pdf

2130-del-2007-drawings.pdf

2130-del-2007-form-1.pdf

2130-del-2007-Form-18-(04-09-2008).pdf

2130-del-2007-form-2.pdf

2130-del-2007-form-3.pdf

2130-del-2007-form-5.pdf

abstract.jpg