Title of Invention

A PROCESS FOR THE PREPARATION OF SUPPORTED COPPER CATALYST

Abstract

A process for the preparation of supported copper catalyst. This invention provides to a process for the preparation of supported copper catalyst useful for production of imino dicarboxylic acid. Particularly it relates to preparation of copper catalyst supported on an alkali resistant transition metal oxide such as copper oxide, nickel oxide or thorium dioxide wherein source of copper may be copper aluminum alloy or devardes alloy comprising copper, aluminium and zinc.

Full Text

This invention relates to a process for the preparation of supported copper catalyst. More particularly it relates to a process for the preparation of the said catalyst useful for production of imino dicarboxylic acid. Still more particuiariy it relates to preparation of copper catalyst supported on an alkali resistant transition metal oxide such as copper oxide, nickel oxide or thorium dioxide. In the prior art described in text books, the supported copper catalysts are prepared by following methods: (a) by impregnating a porous material such as silica gel, pumice stone, metal oxides such as zirconia with a solution of cupric nitrate, drying the mass and reducing it in a current of hydrogen at high temperature (b) by impregnating above porous material supports with a solution of cupric formate followed by drying the solution and decomposing the salt thermally in an inert atmosphere and (c) by depositing the metal chemically from a solution upon the porous support material. The catalysts prepared by the above mentioned processes are suitable for variety of applications such as reduction of nitro to amino compounds, hydrogenation of oiefinic organic molecules and vegetable oils, but are unsuitable for the dehydrogenation of aminoaicohols such as ethanoiatoines to carboxylic acids. The use of copper catalysts for the above conversion has been reported in the prior art [ US Pat. Nos. 4,782,183, 5,292,936 and 5,367,112]. In this case the main drawbacks are (a) shorter life of the catalyst (b) longer reaction time and (c) larger quantity of catalyst requirement. The use of the novel catalysts of the present invention to convert an aminoalcohol to the corresponding acid salt results in reducing (a) the quantity of catalyst and (b) the reaction period considerably compared to those required for other copper catalysts including Raney copper catalysts. This also results in significant savings of raw material and operational costs when such reactions are practiced on commercial scale. It has been found that upon repeated usage of the Raney copper catalyst, the catalyst tends to agglomerate, suffers loss in surface area and subsequently the activity of the catalyst decreases. The activity of the catalyst described in the present invention can be extended to a significant degree, permitting more economic utilization of the catalyst. The object of the present invention therefore is to provide a process for the preparation of supported copper catalysts, supported on transition metal oxides. Accordingly the present invention provides a process for the preparation of supported copper catalyst which comprises of impregnating copper from a source of copper selected from copper aluminium alloy or devardes alloy comprising copper, aluminium and zinc, on a transition metal oxide support such as herein described, under constant stirring for a period of 2 to 6 hrs at a temperature in the range of 50-90°C wherein percentage of copper to the transition metal support material is 10-80%, adding to this mixture 10% excess of an alkali solution such as described herein, washing with de-ionized water to get the desired supported copper catalyst. In one of the embodiments of the present invention the source of copper may be copper aluminium alloy and Devardas alloy, comprising of an alloy of copper, aluminium and zinc. In another embodiment, the copper is prepared from a copper salt solution such as copper-sulphate, chloride, nitrate and acetate by chemical reduction with hydrazine hydrate. In yet another embodiment of the invention, the transition metal oxide supported used may be copper oxide, nickel oxide or thorium dioxide. Hydroxides of alkali metals which are usable for leaching the copper containing alloys mentioned in this invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide, preferably sodium hydroxide and potassium hydroxide. In still another embodiment the weight % of alkali resistant oxide support to the catalyst may be in the range of 10 to 80%. In another embodiment of the present invention the supported copper catalyst can be prepared either by the in situ deposition of copper by leaching Cu-Al alloy in presence of a support material (CuO, Cu2O, NiO, ThO2) in alkaline medium or by physical mixing of support with Raney copper in aqueous medium. The active copper can also be deposited on the support by in situ reduction of copper salt with hydrazine hydrate. The process of the present invention is by no means restricted by the specific examples given below: Example-i Into a 500 ml beaker was placed copper oxide (CuO; support) (8 g), Cu-AI alloy 50/50 wt%; 6 g ) and water (200 ml), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aluminate. bxampie -2 Into a 500 ml beaker was placed cuprous oxide (Cu2O; support) (8 g), Cu-Al alloy 50/50 wt%; 6 g) and water (200 ml), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aluminate. Example -3 Into a 500 ml beaker was placed nickel oxide (NiO; support) (8 g), Cu-Al alloy 50/50 wt%; 6 g) and water (200 ml), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aiuminate. Exampie-4 Into a 500 ml beaker was placed thorium dioxide (ThO2. support) (8 g), Cu-Ai alloy 50/50 wt%; 6 g) and water (200 ml), and the mixture was stirred using a magnetic bar. 10 the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aluminate. Example-5 Into a 500 mi beaker was placed copper oxide (CuO; support) (8 g), Devardas alloy, 6 g (wt% composition of the alloy : Cu 50, Al 45, Zn 5) and water (200 mi), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aiuminate. Exampie-6 Into a 500 mi beaker was placed cuprous oxide (Cu2O; support) (8 g), Devardas alloy, 6 g (wt% composition of the alloy : Cu 50, Al 45, Zn 5) and water (200 mi), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aiuminate. Exampie-7 Into a 500 mi beaker was placed nickel oxide (NiO; support) (8 g), Devardas alloy, 6 g (wt% composition of the alloy : Cu 50, Al 45, Zn 5) and water (200 mi), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to complete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aiuminate. Exampie-8 Into a 500 mi beaker was placed thorium dioxide (ThO2; support) (8 g), Devardas alloy, 6 g (wt% composition of the alloy : Cu 50, Al 45, Zn 5) and water (200 mi), and the mixture was stirred using a magnetic bar. To the stirred solution was added a 50% aqueous solution containing KOH (24 g) drop by drop at 60°C. When the addition was over, the slurry was allowed to stand for a further 4 h. period to compiete the leaching. The catalyst was then washed with de-ionised water repeatedly to remove potassium aluminate. The details of the application of supported copper catalysts in the preparation of aminocarboxylic acid salts are given in our co-pending patent application no. 100/DEL/1999. Claim: 1 . A process for the preparation of supported copper catalyst which comprises of impregnating copper from a source of copper selected from copper aluminium alloy or devardas alloy comprising copper, aluminium and zinc, on a transition metal oxide support such as herein described, under constant stirring for a period of 2 to 6 hrs, at a temperature in the range of 50-90°C wherein percentage of copper to the transition metal support material is 10-80%, adding to this mixture 10% excess of an alkali solution such as described herein, washing with de-ionized water to get the desired supported copper catalyst. 2. A process as claimed in claim 1 in which the transition metal oxide support used is copper oxide, nickel oxide or thorium dioxide. 3. A process as claimed in claims 1 & 2 in which the alkali used is potassium hydroxide, sodium hydroxide, rubidium hydroxide or cesium hydroxide, preferably potassium hydroxide or sodium hydroxide. 4. A process for the preparation of supported copper catalyst as substantially described hereinbefore with reference to the examples contained therein.

Documents:

534-del-1999-abstract.pdf

534-del-1999-claims.pdf

534-del-1999-correspondence-others.pdf

534-del-1999-correspondence-po.pdf

534-del-1999-description (complete).pdf

534-del-1999-form-1.pdf

534-del-1999-form-19.pdf

534-del-1999-form-2.pdf