Title of Invention	A PROCESS FOR THE ACTIVATION OF A METALLIC PALLADIUM BASED CATALYST, USEFUL FOR THE DIRECT OXIDATION OF HYDROGEN BY OXYGEN TO HYDROGEN PEROXIDE
Abstract	A process for the activation of a metallic palladium based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide by treating the palladium metal containing catalyst with an oxidizing agent to oxidize the metallic palladium to palladium (II) oxide (PdO) and optionally calcining the treated catalyst at a temperature in the range from 50°C to 500°C to obtain the desired activated palladium containing catalyst.

Title of Invention

A PROCESS FOR THE ACTIVATION OF A METALLIC PALLADIUM BASED CATALYST, USEFUL FOR THE DIRECT OXIDATION OF HYDROGEN BY OXYGEN TO HYDROGEN PEROXIDE

Abstract

A process for the activation of a metallic palladium based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide by treating the palladium metal containing catalyst with an oxidizing agent to oxidize the metallic palladium to palladium (II) oxide (PdO) and optionally calcining the treated catalyst at a temperature in the range from 50°C to 500°C to obtain the desired activated palladium containing catalyst.

Full Text	This invention relates to a process for the activation of a metallic palladium based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide. This invention particularly relates to a process for the activation by bulk oxidation of metallic palladium of a catalyst comprising metallic palladium for drastically increasing its selectivity and yield in the direct oxidation of hydrogen by oxygen to hydrogen peroxide and also for drastically decreasing its hydrogen peroxide decomposition activity, and thereby making the catalyst much more useful for the direct oxidation of hydrogen to hydrogen peroxide. The activated catalyst of the process of this invention can be used in chemical industries for the direct oxidation of hydrogen to hydrogen peroxide. At present, hydrogen peroxide is produced mostly by the anthraquinone process. However, this process is not environmentally clean and also it has a number of limitations (Ref. Goor et.el." Hydrogen peroxide" In Ullaman's Encyclopedia of Industrial Chemistry, Eds. Elver et.al, p. 443 - 466 , Vol. A13 year 1989, Publisher, VCH Verlangsgeselschft mBH, Weinheim.) . Demand for hydrogen peroxide has been increasing day-by-day for oxidizing organic compounds to value added products, waste-water treatment and water disinfection. Hence, there is a great practical need for replacing the anthraquinone process by an environmentally clean and more economic process such as a direct partial oxidation of hydrogen by oxygen to hydrogen peroxide with high conversion and selectivity. Since the disclosure in U.S. patent 1,108,752 by Henkel et al. that palladium is a catalyst promoting the formation of hydrogen peroxide and water from a mixture of hydrogen and oxygen, a number of palladium containing catalysts, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide, have been disclosed by many inventors. A U.S. patent 4,832,938 by Gosser et al. disclosed a Pt-Pd.bimetallic catalyst supponed on a carbon, silica or alumina support for making hydrogen peroxide from direct combination of hydrogen and oxygen in an aqueous reaction medium. Later, a German patent Ger. Offen. DE 4.127,918 Al by Lueckoff et al. disclosed a supported palladium gold catalyst for the manufacture of hydrogen peroxide from hydrogen and oxygen in aqueous medium; the catalyst contains 5 - 95 wt % Au and is supported on carbon. A number of platinum Group metal containing catalysts: (1) Pt-Group metal on high surface area support, such as carbon, silica or alumina (Ref. U.S. patent 5,169,618); (2) Pt-Group catalyst on solid acid carrier (Ref. Eur. Pat. Appl, EP 504.741. Al); (3) Pt-Group element supported on Mb- or Ta oxide (Ref. PCT Int. Appl. WO 9,412,428 Al), (4) Sn- modified Pt-Group metals supported on catalysts carriers (Ref. Eur. Pat. Appl. EP 621,235 Al); (5) Pt-Group metal catalyst supported on hydrophilic support (Ref. U.S. patent 5.399,334), for the oxidation of hydrogen to hydrogen peroxide are known in the prior art. A Japanese patent Jpn, Kokai Tokkyo Koho JP 01133909 A2 by Kyora disclosed a Pt-Group metal catalyst carried on a hydrophobic support such as porous and hydrophobic Teflon support. Chuang in an European patent EP 3660419 Al disclosed a Group VIII metal catalyst deposited on a hydrophobic support for the manufacture of hydrogen peroxide by reacting hydrogen with oxygen in an aqueous medium. Later , Chuang has disclosed a Group V1I1 metal on a partially hydrophobic and partially hydrophilic support, such as Pd on fluorinated carbon, as a catalyst for the oxidation of hydrogen to hydrogen peroxide, in PCT Int. Appl. WO 93 14025 Al. Inspite of the extensive earlier work disclosed in the prior art. the direct oxidation of hydrogen to hydrogen peroxide has not yet been practiced for the production of hydrogen peroxide. One of the reasons for this is the poor selectivity observed in this process. Fu et.al reported the maximum selectivity of 8.7% for hydrogen peroxide in the oxidation of hydrogen by oxygen over palladium metal supported on fluorided carbon They have also reported that the catalyst having higher hydrogen peroxide decomposition activity shows lower selectivity in the direct oxidation of hydrogen to hydrogen peroxide (Ref. Fu et.al. Stud.Surf. Sci .Catal. Vol. 72, p. 33 - 41, Year 1992). Hence, it is of great practical importance to develop a better catalyst comprising palladium, which has higher selectivity for hydrogen peroxide in the oxidation of hydrogen by oxygen to hydrogen peroxide but has lower activity for the decomposition of hydrogen peroxide under the similar conditions. The main object of the present invention is to provide a process for the activation of a catalyst comprising palladium so that the hydrogen peroxide selectivity in the oxidation of hydrogen by oxygen over the catalyst is increased drastically. An other object of this invention is to provide a process for the activation of a catalyst comprising palladium so that the yield for hydrogen peroxide in the oxidation of hydrogen by-oxygen over the catalyst is increased drastically. Yet another object of this invention is to provide a process for the activation of a catalyst comprising palladium so that the hydrogen peroxide decomposition activity of the catalyst is reduced drastically. These and other objects are accomplished in this invention by providing a process for the activation of a catalyst comprising palladium metal useful for the direct oxidation of hydrogen to hydrogen peroxide. Accordingly the present invention provides a process for the activation of a catalyst comprising metallic palladium . useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide, which comprises oxidising the metallic palladium present in a catalyst with Accordingly the present invention provides a process for the activation of a metallic palladium based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide, which comprises treating the palladium metal containing catalyst with an oxidizing agent such as herein described to oxidize the metallic palladium to palladium (II) oxide (PdO) and optionally calcining the treated catalyst at a temperature in the range from 50°C to 500°C to obtain the desired activated palladium containing catalyst. In an embodiment of the present invention the oxidizing agent used is selected from the group consisting of perchloric acid (HC1O4) , hydrogen peroxide (H2O2), nitrous oxide (N2O), oxygen and air. In yet another embodiment the calcination temperature of the treated catalyst is in the range from 100°Cto 300°C. In still another embodiment a process is carries out not only a surface oxidation but also at least a partial bulk oxidation of the metallic palladium, present in the catalyst. In the process of this invention, the activation of a catalyst comprising metallic palladium by its treatment with an oxidizing agent involves at least a partial bulk oxidation of the metallic palladium to palladium oxide. Examples of the oxidizing agents are perchloric acid, perbromic acid, periodic acid, hydrogen peroxide, nitrous oxide, oxygen or air, potassium permagnate, potassium dichromate and the like. The oxidizing agent for the process of this invention is preferably selected from perchloric acid (HC104), hydrogen peroxide (H2O2), nitrous oxide (N2O), oxygen and air. The catalyst comprising palladium metal may contain a palladium metal, with or without one or more of other noble metals, such as platinum, ruthenium, rhodium, iridium and osmium and also with or without one or more promoter metals, such as tin, gold and other metal promoters, supported on catalyst carriers such as, carbon, alumina, silica-alumina, silica, zeolites, zirconia, thoria, ceria and other metal oxides or mixed metal oxides in form of powder, particles, pellets, extrudes or monolith and structured metallic catalyst supports. In the process of this invention, the activation of said catalyst by its treatment with an oxidizing agent may be carried out in a liquid phase or in a vapour phase, depending up on the state of the oxidizing agent. The catalyst activation by a liquid oxidizing agent, such as perchloric acid and hydrogen peroxide may be earned out in a liquid phase at a temperature below about 100°C. and after the activation, the treated catalyst may be dried and calcined under vacuum or under air or innert gas such as nitrogen, helium or argon, at a temperature below 500°C. preferably at a temperature in the range from 100°C to 500°C. Whereas the catalyst activation by a gaseous oxidizing agent, such as nitrous oxide and oxygen or air, may be carried out in a gas phase at temperature at or below about 500°C, and in this case, after the activation there is no need to dry or to calcine the treated catalyst. In the process of this invention, the role of the oxidizing agent is to oxidize the bulk palladium metal from said catalyst to palladium oxide, at least partially and the role of the calcination of the treated catalyst is to dry and/or to remove by decomposing the oxidizing agent remained in the treated catalyst. The product of the process of invention is an activated catalyst comprising palladium oxide, useful for the direct oxidation of hydrogen to hydrogen peroxide By the process of this invention a catalyst comprising metallic palladium is activated by the bulk oxidation of its metallic palladium at least partially to palladium(II) oxide, and thereby the hydrogen peroxide decomposition activity of the catalyst is decreased drastically, and consequently the selectivity and yield for hydrogen peroxide in the direct oxidation of hydrogen by oxygen to hydrogen peroxide over the catalyst are increased by several folds. The present invention is described with respect to the following examples illustrating the process of this invention for the activation of a catalyst comprising palladium metal, useful for direct oxidation of hydrogen by oxygen to hydrogen peroxide. These examples are provided for illustrative purposes only and therefore should not be construed to limit the scope of the present invention Definition of terms used in the examples Conversion of H2 (%) = mole % of the hydrogen converted to all products Selectivity for H202 (%) - [(conversion of H2 to H202 (%)}/'{conversion of H2 to all products (%)}]x 100 Yield of H20: (%) = mole % of H2 converted to H2O: = [ {conversion of H2 (%),' x {selectivity for H202 (%)}]/ 100 Conversion of H2O2 = mole % of the hydrogen peroxide decomposed to water and oxygen The flow rate of gases is measured at 0UC and 1 atm. pressure. Gas hourly space velocity (GHSY) is a volume of gas. measured at 0"C and 1 atm. pressure, passed or bubbled through unit volume of liquid reaction medium containing catalyst per hour. EXAMPLE-1 This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with 0.1 M perchloric acid and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by 02 to H:O2 over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drasticalh' by the activation of the catalyst. The activation of Pd(5 wt%) / Carbon in powder form, obtained from Lancaster Chemicals. England, was carried out by treating 5 g. of the catalyst with 9 ml of 0 1M perchloric acid (HC104), while forming a paste, and then drying the paste at 80°C for 2 h. The dried mass was then calcined in static air at 300°C for 2h to provide the activated Pd/Carbon catalyst. The crystalline phases of Pd-compounds present in the catalyst before and after the activation were determined from the Powder X-ray diffraction of the catalyst, using a Holland. Philips. PW 1730 X-ray generator with Cu K-α radiation's. The direct oxidation of H2 by 0: to H2O2 over the catalyst was carried out at atmospheric pressure in a magnetically stirred glass reactor (capacity = 250 cm-3) containing 0.5 g catalyst and 150 cm-3 of 0.02M sulfuric acid, as a reaction medium, by bubbling a mixture of H2 and 0: containing 2.0 moi% H: at a flow rate of 12 cm-1 min"1 . through the reaction medium at 22 or 35"C for 3h. The concentration of hydrogen in the reactor effluent gases was measured by an on-line hydrogen gas analyzer. The H^O? formed in the oxidation reaction was determined quantitatively by measuring the concentration of hydrogen peroxide in the reaction medium, after the reaction, by the idometric titration method The decomposition of hydrogen peroxide over the catalyst was carried out at atmospheric pressure in the same reactor, described above, containing 0.2 g catalyst. 105 cm" of 0.02 M sulfuric acid and 0.3 g of hydrogen peroxide at 22 or 35"C as a function of time The amount of oxygen evolved in the H2O2 decomposition according to the reaction : H2O2 → H20 + 0.5 O2 , was measured quantitatively as a function of time, by collecting it over water using a constant pressure gas collector described earlier (Choudhary et.al. Ind.Eng.Chem Fundamental. Vol. 21. p. 472, year 1982). Results on the catalyst with and without the activation are presented in Table Table 1 : Results on the Pd/ carbon with and without the activation by the O.I M perchloric acid treatment (Table Removed) EXAMPLE - 2 This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with 1.0 M perchloric acid and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by O2 to H2O2 over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst. The activation of the catalyst was carried out by the procedure same as that described in Example-1 except that 1 M HCl04 was used instead of 0.1 M HC1O4. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 02 to H202; and also in the H2O decomposition were determined using the same methods and experimental procedures described in Example-1 The results on the catalyst with or without the activation are presented in Table-2. Table 2 : Results on the Pd/ carbon with and without the activation by the 1.0 M perchloric acid treatment (Table Removed) EXAMPLE-3 This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with hydrogen peroxide and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by O: to H:0: over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The activation of the catalyst same as that described in Example-1, was carried out by treating 1.0 g catalyst with 40 cm-3 of 30% H202 solution at 30°C for 2h and after the treatment, the catalyst was filtered and dried at 100°C for 2h. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 0: to H2O2 and also in then H202 decomposition were determined using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table-3. Table-3 : Results on the Pd/ carbon with and without the activation by the hydrogen peroxide treatment (Table Removed) EXAMPLE-4 This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with nitrous oxide and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by 02 to H:0; over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalvst The activation of the catalyst, same as that described in Example-1. was carried out by contacting it with N20 gas at a space velocity of 300 cm-3.g-1h-1 at 250°C in a tubular quartz reactor (i.d = 10 mm ) for a period of 2h. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 0; to H2O: and also in the H202 decomposition were studied using the same methods and experimental procedures described in Example-!. The results on the catalyst with or without the activation are presented in Table-4. Table 4 : Results on the Pd/carbon with and without the activation by the N2O treatment (Table Removed) EXAMPLE - 5 This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with air and also shows that the hydrouen peroxide selectivity and yield in the direct oxidation of H2 by O: to H2O: over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The activation of the catalyst was carried out by heating Pd (5 wt%)/alumina catalyst, obtained from Lancaster Chemicals, England, under static air in muffle furnace at 500°C for 2h. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0; to H2O2 and also in the H2O2 decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table-5. Table 5 : Results on the Pd/alumina with and without the activation by the air treatment (Table Removed) EXAMPLE - 6 This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with N20 and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by O2 to H:02 over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The activation of the catalyst, same as that described in Example-5. was carried out bv the same procedure as that described in Example-4 The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 0: to H202 and also in the H2O: decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 6. Table 6 : Results on the Pd/alumina with and without the activation by the N2O treatment (Table Removed) EXAMPLE-7 This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with H:02 and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by 0: to H:02 over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The activation of the catalyst,' same as that described in Example - 5. was carried out by the procedure same as that described in Example - 3. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0; to H202 and also in the H202 decomposition was studied using the same methods and experimental procedures described in Example-1. The results on the activated catalyst with that of without the activation are presented in Table - 7. Table 7 : Results on the Pd alumina with or without the activation by the hydrogen peroxide treatment (Table Removed) EXAMPLE - 8 This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with HC104 and also shows that the hydrogen peroxide selectivity and yield in trie-direct oxidation of H2 by 02 to H2O2 over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The activation of the catalyst, same as that described in Example - 5. was carried out by the procedure same as that described in Example - 1. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 02 to H2O2 and also in the H202 decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 8. Table 8 : Results on the Pd/alumina with and without the activation by the perchloric acid treatment (Table Removed) EXAMPLE-9 This example illustrates the process of this invention for the activation of Pd, CeO2 catalyst by its treatment with oxygen and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by O: to H:0: over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The Pd (2.5 wt%)/CeO2 catalyst was prepared by impregnating palladium chloride on CeO: and then by reducing the impregnated catalyst mass with ammoniacal solution of hydrazine. After the reduction the catalyst was washed with pure water and then dried on water bath. The activation of the Pd/CeO2 catalyst was carried out by contacting it with pure oxygen at 500°C in a quartz tubular reactor at a space velocity of 500 cm-3g-1h-1 for 2h. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0: to H20: and also in the H:02 decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table -9 Table 9 : Results on the Pd/ CeO2 with and without the activation by the oxygen treatment (Table Removed) EXAMPLE- 10 This example illustrates the process of this invention for the activation of Pd/ ThO2 catalyst by its treatment with air and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by 0: to H:O2 over the catalvst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The Pd (2.5 wt%)/ThO2 catalyst was prepared by impregnating palladium chloride on ThO2 and then by reducing the impregnated catalyst mass with ammoniacal solution of hydrazine. After the reaction the catalvst was washed with pure water and then dried on water bath. The activation of the Pd/ThO2 catalyst was earned out by the procedure same as that described in Example - 5. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H; by 0: to H2O2 and also in the H2O decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 10 Table 10 : Results on the Pd/ ThO2 with and without the activation by the air treatment (Table Removed) EXAMPLE- 11 This example illustrates the process of this invention for the activation of Pd- Pt/ Ga203 catalyst by its treatment with air and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by 0: to H:O: over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst The Pd (2.5 wt%) - Pt (0.13 wt%)/ Ga203 catalyst was prepared by impregnating requisite amount of palladium chloride and chloroplatinic acid on Ga2O3 and then by reducing the impregnated catalyst mass with ammoniacal solution of hydrazine. After the reaction, the catalyst was washed with pure water and then dried on water bath The activation of the Pd - Pt/ Ga2O3 catalyst was carried out by the procedure same as that described in Example - 10. The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0: to H2O2 and also in the H:0: decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 11. Table 11 : Results on the Pd - Pt / Ga2O3 with and without the activation by the air treatment (Table Removed) From the results in all the above 1 1 examples, following important observations or conclusions can be made: 1 After the activation by the process of this invention, the metallic palladium present in the different catalysts is partially oxidized to PdO 2. Because of the catalyst activation by the process of this invention, the selectivity and yield for H2O2 in the direct oxidation of H2 to H2O: are increased bv several folds and also in most cases the H2 conversion is also increased 3. Because of the catalvst activation bv the process of this invention, the hydrogen peroxide decomposition activity of the catalvst is reduced drastically Important Novel Features and Advantages of the process of this invention are as follows: 1. By the process of this invention, the catalysts comprising palladium metal are activated by treating them with an oxidizing agent and thereby the hydrogen peroxide selectivity and yield of the catalysts in the direct oxidation of H: to H202are increased by several folds. 2. In the activation of catalysts by the process of this invention . there is a bulk oxidation of at least a part of palladium, present in the catalyst, to palladium oxide. 3. Because of the activation of the catalysts comprising palladium by the process of this invention, the hydrogen peroxide decomposition activity of the catalysts is reduced drastically, and thereby the selectivity for the formation of hydrogen peroxide in the direct oxidation of H; to H^O: is increased. We Claim: 1. A process for the activation of a metallic palladium based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide, which comprises treating the palladium metal containing catalyst with an oxidizing agent such as herein described to oxidize the metallic palladium to palladium (II) oxide (PdO) and optionally calcining the treated catalyst at a temperature in the range from 50°C to 500°C to obtain the desired activated palladium containing catalyst. 2. A process as claimed in claim 1 wherein the oxidizing agent is selected from the group consisting of perchloric acid, perbronic acid, periodic acid, hydrogen peroxide nitrous oxide, potassium permanganate potassium dichromatic & mixtures thereof 3. A process as claimed in claims 1-2, wherein the calcination temperature of the treated catalyst is in the range from 100°C to 300°C preferably. 4. A process for the activation of a catalyst comprising metallic palladium , useful for the direct oxidation of hydrogen to hydrogen peroxide, substantially as herein described with reference to the examples.

Full Text

This invention relates to a process for the activation of a metallic palladium based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide. This invention particularly relates to a process for the activation by bulk oxidation of metallic palladium of a catalyst comprising metallic palladium for drastically increasing its selectivity and yield in the direct oxidation of hydrogen by oxygen to hydrogen peroxide and also for drastically decreasing its hydrogen peroxide decomposition activity, and thereby making the catalyst much more useful for the direct oxidation of hydrogen to hydrogen peroxide.
The activated catalyst of the process of this invention can be used in chemical industries for the direct oxidation of hydrogen to hydrogen peroxide. At present, hydrogen peroxide is produced mostly by the anthraquinone process. However, this process is not environmentally clean and also it has a number of limitations (Ref. Goor et.el." Hydrogen peroxide" In Ullaman's Encyclopedia of Industrial Chemistry, Eds. Elver et.al, p. 443 - 466 , Vol. A13 year 1989, Publisher, VCH Verlangsgeselschft mBH, Weinheim.) . Demand for hydrogen peroxide has been increasing day-by-day for oxidizing organic compounds to value added products, waste-water treatment and water disinfection. Hence, there is a great practical need for replacing the anthraquinone process by an environmentally clean and more economic process such as a direct partial oxidation of hydrogen by oxygen to hydrogen peroxide with high conversion and selectivity.
Since the disclosure in U.S. patent 1,108,752 by Henkel et al. that palladium is a catalyst promoting the formation of hydrogen peroxide and water from a mixture of hydrogen and oxygen, a number of palladium containing catalysts, useful for the

direct oxidation of hydrogen by oxygen to hydrogen peroxide, have been disclosed by many inventors.
A U.S. patent 4,832,938 by Gosser et al. disclosed a Pt-Pd.bimetallic catalyst supponed on a carbon, silica or alumina support for making hydrogen peroxide from direct combination of hydrogen and oxygen in an aqueous reaction medium. Later, a German patent Ger. Offen. DE 4.127,918 Al by Lueckoff et al. disclosed a supported palladium gold catalyst for the manufacture of hydrogen peroxide from hydrogen and oxygen in aqueous medium; the catalyst contains 5 - 95 wt % Au and is supported on carbon. A number of platinum Group metal containing catalysts: (1) Pt-Group metal on high surface area support, such as carbon, silica or alumina (Ref. U.S. patent 5,169,618); (2) Pt-Group catalyst on solid acid carrier (Ref. Eur. Pat. Appl, EP 504.741. Al); (3) Pt-Group element supported on Mb- or Ta oxide (Ref. PCT Int. Appl. WO 9,412,428 Al), (4) Sn- modified Pt-Group metals supported on catalysts carriers (Ref. Eur. Pat. Appl. EP 621,235 Al); (5) Pt-Group metal catalyst supported on hydrophilic support (Ref. U.S. patent 5.399,334), for the oxidation of hydrogen to hydrogen peroxide are known in the prior art.
A Japanese patent Jpn, Kokai Tokkyo Koho JP 01133909 A2 by Kyora disclosed a Pt-Group metal catalyst carried on a hydrophobic support such as porous and hydrophobic Teflon support. Chuang in an European patent EP 3660419 Al disclosed a Group VIII metal catalyst deposited on a hydrophobic support for the manufacture of hydrogen peroxide by reacting hydrogen with oxygen in an aqueous medium. Later , Chuang has disclosed a Group V1I1 metal on a partially hydrophobic and partially hydrophilic support, such as Pd on fluorinated carbon, as a catalyst for the oxidation of hydrogen to hydrogen peroxide, in PCT Int. Appl. WO 93 14025 Al.

Inspite of the extensive earlier work disclosed in the prior art. the direct oxidation of hydrogen to hydrogen peroxide has not yet been practiced for the production of hydrogen peroxide. One of the reasons for this is the poor selectivity observed in this process. Fu et.al reported the maximum selectivity of 8.7% for hydrogen peroxide in the oxidation of hydrogen by oxygen over palladium metal supported on fluorided carbon They have also reported that the catalyst having higher hydrogen peroxide decomposition activity shows lower selectivity in the direct oxidation of hydrogen to hydrogen peroxide (Ref. Fu et.al. Stud.Surf. Sci .Catal. Vol. 72, p. 33 - 41, Year 1992). Hence, it is of great practical importance to develop a better catalyst comprising palladium, which has higher selectivity for hydrogen peroxide in the oxidation of hydrogen by oxygen to hydrogen peroxide but has lower activity for the decomposition of hydrogen peroxide under the similar conditions.
The main object of the present invention is to provide a process for the activation of a catalyst comprising palladium so that the hydrogen peroxide selectivity in the oxidation of hydrogen by oxygen over the catalyst is increased drastically.
An other object of this invention is to provide a process for the activation of a catalyst comprising palladium so that the yield for hydrogen peroxide in the oxidation of hydrogen by-oxygen over the catalyst is increased drastically.
Yet another object of this invention is to provide a process for the activation of a catalyst comprising palladium so that the hydrogen peroxide decomposition activity of the catalyst is reduced drastically.
These and other objects are accomplished in this invention by providing a process for the activation of a catalyst comprising palladium metal useful for the direct oxidation of hydrogen to hydrogen peroxide.
Accordingly the present invention provides a process for the activation of a catalyst comprising metallic palladium . useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide, which comprises oxidising the metallic palladium present in a catalyst with

Accordingly the present invention provides a process for the activation of a metallic palladium
based catalyst, useful for the direct oxidation of hydrogen by oxygen to hydrogen peroxide, which
comprises treating the palladium metal containing catalyst with an oxidizing agent such as herein
described to oxidize the metallic palladium to palladium (II) oxide (PdO) and optionally calcining
the treated catalyst at a temperature in the range from 50°C to 500°C to obtain the desired
activated palladium containing catalyst.
In an embodiment of the present invention the oxidizing agent used is selected from the group
consisting of perchloric acid (HC1O4) , hydrogen peroxide (H2O2), nitrous oxide (N2O), oxygen
and air.
In yet another embodiment the calcination temperature of the treated catalyst is in the range from
100°Cto 300°C.
In still another embodiment a process is carries out not only a surface oxidation but also at least a
partial bulk oxidation of the metallic palladium, present in the catalyst.
In the process of this invention, the activation of a catalyst comprising metallic palladium by its
treatment with an oxidizing agent involves at least a partial bulk oxidation of the metallic
palladium to palladium oxide. Examples of the oxidizing agents are perchloric acid, perbromic
acid, periodic acid, hydrogen peroxide, nitrous oxide, oxygen or air, potassium permagnate,
potassium dichromate and the like. The oxidizing agent for the process of this invention is
preferably selected from perchloric acid (HC104), hydrogen peroxide (H2O2), nitrous oxide (N2O),
oxygen and air.
The catalyst comprising palladium metal may contain a palladium metal, with or without one or
more of other noble metals, such as platinum, ruthenium, rhodium, iridium and osmium and also
with or without one or more promoter metals, such as tin, gold and other metal promoters,
supported on catalyst carriers such as, carbon, alumina, silica-alumina, silica, zeolites, zirconia,
thoria, ceria and other metal oxides or mixed metal oxides in form of powder, particles, pellets,
extrudes or monolith and structured metallic catalyst supports.
In the process of this invention, the activation of said catalyst by its treatment with an oxidizing
agent may be carried out in a liquid phase or in a vapour phase, depending up on the state
of the oxidizing agent. The catalyst activation by a liquid

oxidizing agent, such as perchloric acid and hydrogen peroxide may be earned out in a liquid phase at a temperature below about 100°C. and after the activation, the treated catalyst may be dried and calcined under vacuum or under air or innert gas such as nitrogen, helium or argon, at a temperature below 500°C. preferably at a temperature in the range from 100°C to 500°C. Whereas the catalyst activation by a gaseous oxidizing agent, such as nitrous oxide and oxygen or air, may be carried out in a gas phase at temperature at or below about 500°C, and in this case, after the activation there is no need to dry or to calcine the treated catalyst.
In the process of this invention, the role of the oxidizing agent is to oxidize the bulk palladium metal from said catalyst to palladium oxide, at least partially and the role of the calcination of the treated catalyst is to dry and/or to remove by decomposing the oxidizing agent remained in the treated catalyst.
The product of the process of invention is an activated catalyst comprising palladium oxide, useful for the direct oxidation of hydrogen to hydrogen peroxide
By the process of this invention a catalyst comprising metallic palladium is activated by the bulk oxidation of its metallic palladium at least partially to palladium(II) oxide, and thereby the hydrogen peroxide decomposition activity of the catalyst is decreased drastically, and consequently the selectivity and yield for hydrogen peroxide in the direct oxidation of hydrogen by oxygen to hydrogen peroxide over the catalyst are increased by several folds.
The present invention is described with respect to the following examples illustrating the process of this invention for the activation of a catalyst comprising palladium metal, useful for direct oxidation of hydrogen by oxygen to hydrogen peroxide. These examples are provided for illustrative purposes only and therefore should not be construed to limit the scope of the present invention

Definition of terms used in the examples
Conversion of H2 (%) = mole % of the hydrogen converted to all products Selectivity for H202 (%) - [(conversion of H2 to H202 (%)}/'{conversion of
H2 to all products (%)}]x 100
Yield of H20: (%) = mole % of H2 converted to H2O:
= [ {conversion of H2 (%),' x {selectivity for H202 (%)}]/ 100
Conversion of H2O2 = mole % of the hydrogen peroxide decomposed to
water and oxygen
The flow rate of gases is measured at 0UC and 1 atm. pressure. Gas hourly space velocity (GHSY) is a volume of gas. measured at 0"C and 1 atm. pressure, passed or bubbled through unit volume of liquid reaction medium containing catalyst per hour. EXAMPLE-1
This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with 0.1 M perchloric acid and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by 02 to H:O2 over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drasticalh' by the activation of the catalyst.
The activation of Pd(5 wt%) / Carbon in powder form, obtained from Lancaster Chemicals. England, was carried out by treating 5 g. of the catalyst with 9 ml of 0 1M perchloric acid (HC104), while forming a paste, and then drying the paste

at 80°C for 2 h. The dried mass was then calcined in static air at 300°C for 2h to provide the activated Pd/Carbon catalyst.
The crystalline phases of Pd-compounds present in the catalyst before and after the activation were determined from the Powder X-ray diffraction of the catalyst, using a Holland. Philips. PW 1730 X-ray generator with Cu K-α radiation's.
The direct oxidation of H2 by 0: to H2O2 over the catalyst was carried out at atmospheric pressure in a magnetically stirred glass reactor (capacity = 250 cm-3) containing 0.5 g catalyst and 150 cm-3 of 0.02M sulfuric acid, as a reaction medium, by bubbling a mixture of H2 and 0: containing 2.0 moi% H: at a flow rate of 12 cm-1 min"1 . through the reaction medium at 22 or 35"C for 3h. The concentration of hydrogen in the reactor effluent gases was measured by an on-line hydrogen gas analyzer. The H^O? formed in the oxidation reaction was determined quantitatively by measuring the concentration of hydrogen peroxide in the reaction medium, after the reaction, by the idometric titration method
The decomposition of hydrogen peroxide over the catalyst was carried out at atmospheric pressure in the same reactor, described above, containing 0.2 g catalyst. 105 cm" of 0.02 M sulfuric acid and 0.3 g of hydrogen peroxide at 22 or 35"C as a function of time The amount of oxygen evolved in the H2O2 decomposition
according to the reaction : H2O2 → H20 + 0.5 O2 , was measured
quantitatively as a function of time, by collecting it over water using a constant pressure gas collector described earlier (Choudhary et.al. Ind.Eng.Chem Fundamental. Vol. 21. p. 472, year 1982).
Results on the catalyst with and without the activation are presented in Table

Table 1 : Results on the Pd/ carbon with and without the activation by the O.I M perchloric acid treatment
(Table Removed)
EXAMPLE - 2
This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with 1.0 M perchloric acid and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by O2 to H2O2 over the catalyst are increased by many folds and also the hydrogen peroxide

decomposition activity of the catalyst is decreased drastically by the activation of the catalyst.
The activation of the catalyst was carried out by the procedure same as that described in Example-1 except that 1 M HCl04 was used instead of 0.1 M HC1O4.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 02 to H202; and also in the H2O decomposition were determined using the same methods and experimental procedures described in Example-1 The results on the catalyst with or without the activation are presented in Table-2.
Table 2 : Results on the Pd/ carbon with and without the activation by the 1.0 M perchloric acid treatment
(Table Removed)
EXAMPLE-3
This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with hydrogen peroxide and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by O: to H:0: over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The activation of the catalyst same as that described in Example-1, was carried out by treating 1.0 g catalyst with 40 cm-3 of 30% H202 solution at 30°C for 2h and after the treatment, the catalyst was filtered and dried at 100°C for 2h.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 0: to H2O2 and also in then H202 decomposition were determined using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table-3.

Table-3 : Results on the Pd/ carbon with and without the activation by the hydrogen peroxide treatment
(Table Removed)
EXAMPLE-4
This example illustrates the process of this invention for the activation of Pd/carbon catalyst, by its treatment with nitrous oxide and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by 02 to H:0; over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalvst

The activation of the catalyst, same as that described in Example-1. was carried out by contacting it with N20 gas at a space velocity of 300 cm-3.g-1h-1 at 250°C in a tubular quartz reactor (i.d = 10 mm ) for a period of 2h.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 0; to H2O: and also in the H202 decomposition were studied using the same methods and experimental procedures described in Example-!. The results on the catalyst with or without the activation are presented in Table-4.
Table 4 : Results on the Pd/carbon with and without the activation by the N2O treatment

(Table Removed)
EXAMPLE - 5
This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with air and also shows that the hydrouen peroxide selectivity and yield in the direct oxidation of H2 by O: to H2O: over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The activation of the catalyst was carried out by heating Pd (5 wt%)/alumina catalyst, obtained from Lancaster Chemicals, England, under static air in muffle furnace at 500°C for 2h.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0; to H2O2 and also in the H2O2 decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table-5.
Table 5 : Results on the Pd/alumina with and without the activation by the air treatment

(Table Removed)
EXAMPLE - 6
This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with N20 and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by O2 to H:02 over the catalyst are increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The activation of the catalyst, same as that described in Example-5. was carried out bv the same procedure as that described in Example-4

The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 0: to H202 and also in the H2O: decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 6.
Table 6 : Results on the Pd/alumina with and without the activation by the N2O treatment
(Table Removed)
EXAMPLE-7
This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with H:02 and also shows that the hydrogen

peroxide selectivity and yield in the direct oxidation of H: by 0: to H:02 over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The activation of the catalyst,' same as that described in Example - 5. was carried out by the procedure same as that described in Example - 3.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0; to H202 and also in the H202 decomposition was studied using the same methods and experimental procedures described in Example-1. The results on the activated catalyst with that of without the activation are presented in Table - 7.
Table 7 : Results on the Pd alumina with or without the activation by the hydrogen peroxide treatment

(Table Removed)
EXAMPLE - 8
This example illustrates the process of this invention for the activation of Pd/alumina catalyst, by its treatment with HC104 and also shows that the hydrogen peroxide selectivity and yield in trie-direct oxidation of H2 by 02 to H2O2 over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The activation of the catalyst, same as that described in Example - 5. was carried out by the procedure same as that described in Example - 1.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H2 by 02 to H2O2 and also in the H202 decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 8.

Table 8 : Results on the Pd/alumina with and without the activation by the
perchloric acid treatment

(Table Removed)
EXAMPLE-9
This example illustrates the process of this invention for the activation of Pd, CeO2 catalyst by its treatment with oxygen and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by O: to H:0: over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The Pd (2.5 wt%)/CeO2 catalyst was prepared by impregnating palladium chloride on CeO: and then by reducing the impregnated catalyst mass with

ammoniacal solution of hydrazine. After the reduction the catalyst was washed with pure water and then dried on water bath.
The activation of the Pd/CeO2 catalyst was carried out by contacting it with pure oxygen at 500°C in a quartz tubular reactor at a space velocity of 500 cm-3g-1h-1 for 2h.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0: to H20: and also in the H:02 decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table -9
Table 9 : Results on the Pd/ CeO2 with and without the activation by the oxygen treatment

(Table Removed)
EXAMPLE- 10
This example illustrates the process of this invention for the activation of Pd/ ThO2 catalyst by its treatment with air and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H: by 0: to H:O2 over the catalvst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The Pd (2.5 wt%)/ThO2 catalyst was prepared by impregnating palladium chloride on ThO2 and then by reducing the impregnated catalyst mass with ammoniacal solution of hydrazine. After the reaction the catalvst was washed with pure water and then dried on water bath.

The activation of the Pd/ThO2 catalyst was earned out by the procedure same as that described in Example - 5.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H; by 0: to H2O2 and also in the H2O decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 10
Table 10 : Results on the Pd/ ThO2 with and without the activation by the air treatment
(Table Removed)
EXAMPLE- 11
This example illustrates the process of this invention for the activation of Pd- Pt/ Ga203 catalyst by its treatment with air and also shows that the hydrogen peroxide selectivity and yield in the direct oxidation of H2 by 0: to H:O: over the catalyst is increased by many folds and also the hydrogen peroxide decomposition activity of the catalyst is decreased drastically by the activation of the catalyst
The Pd (2.5 wt%) - Pt (0.13 wt%)/ Ga203 catalyst was prepared by impregnating requisite amount of palladium chloride and chloroplatinic acid on Ga2O3 and then by reducing the impregnated catalyst mass with ammoniacal solution of hydrazine. After the reaction, the catalyst was washed with pure water and then dried on water bath
The activation of the Pd - Pt/ Ga2O3 catalyst was carried out by the procedure same as that described in Example - 10.
The crystalline phases of palladium compounds in the catalyst, before and after the treatment, and also the performance of the catalyst, before and after the treatment, in the direct oxidation of H: by 0: to H2O2 and also in the H:0: decomposition were studied using the same methods and experimental procedures described in Example-1. The results on the catalyst with or without the activation are presented in Table - 11.
Table 11 : Results on the Pd - Pt / Ga2O3 with and without the activation by the air treatment

(Table Removed)
From the results in all the above 1 1 examples, following important observations or conclusions can be made:
1 After the activation by the process of this invention, the metallic palladium present in the different catalysts is partially oxidized to PdO
2. Because of the catalyst activation by the process of this invention, the selectivity
and yield for H2O2 in the direct oxidation of H2 to H2O: are increased bv several
folds and also in most cases the H2 conversion is also increased
3. Because of the catalvst activation bv the process of this invention, the hydrogen
peroxide decomposition activity of the catalvst is reduced drastically

Important Novel Features and Advantages of the process of this invention are as follows:
1. By the process of this invention, the catalysts comprising palladium metal are activated by treating them with an oxidizing agent and thereby the hydrogen peroxide selectivity and yield of the catalysts in the direct oxidation of H: to H202are increased by several folds.
2. In the activation of catalysts by the process of this invention . there is a bulk
oxidation of at least a part of palladium, present in the catalyst, to palladium
oxide.
3. Because of the activation of the catalysts comprising palladium by the process
of this invention, the hydrogen peroxide decomposition activity of the
catalysts is reduced drastically, and thereby the selectivity for the formation of
hydrogen peroxide in the direct oxidation of H; to H^O: is increased.

We Claim:
1. A process for the activation of a metallic palladium based catalyst, useful for the
direct oxidation of hydrogen by oxygen to hydrogen peroxide, which comprises
treating the palladium metal containing catalyst with an oxidizing agent such as
herein described to oxidize the metallic palladium to palladium (II) oxide (PdO) and
optionally calcining the treated catalyst at a temperature in the range from 50°C to
500°C to obtain the desired activated palladium containing catalyst.
2. A process as claimed in claim 1 wherein the oxidizing agent is selected from the
group consisting of perchloric acid, perbronic acid, periodic acid, hydrogen
peroxide nitrous oxide, potassium permanganate potassium dichromatic & mixtures
thereof
3. A process as claimed in claims 1-2, wherein the calcination temperature of the
treated catalyst is in the range from 100°C to 300°C preferably.
4. A process for the activation of a catalyst comprising metallic palladium , useful for
the direct oxidation of hydrogen to hydrogen peroxide, substantially as herein
described with reference to the examples.

Documents:

1026-del-2000-abstract.pdf

1026-del-2000-claims.pdf

1026-del-2000-correspondence-others.pdf

1026-del-2000-correspondence-po.pdf

1026-del-2000-description (complete).pdf

1026-del-2000-form-1.pdf

1026-del-2000-form-19.pdf

1026-del-2000-form-2.pdf

1026-del-2000-petition-137.pdf

1026-del-2000-petition-138.pdf

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Patent Number

232145

Indian Patent Application Number

1026/DEL/2000

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

15-Mar-2009

Date of Filing

17-Nov-2000

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	VASANT RAMCHANDRA CHOUDHARY	CHEMICAL LABORATORY, PUNE-411 008, MAHARASTRA, INDIA.
2	ABAJI GOVIND GAIKWAD	CHEMICAL LABORATORY, PUNE-411008, MAHARASTRA, INDIA.
3	SUBHASH DWARKANATH SANSARE	CHEMICAL LABORATORY, PUNE-411008, MAHARASTRA, INDIA.

PCT International Classification Number

B01J 23/44

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA