Ammonia deposition precipitation process for producing a copper-nickel/gamma-alumina catalyst, said catalyst and its use in the conversion of exhaust gases

Abstract

A process for the production of a catalyst comprising the steps of: dissolving the requisite quantities of copper nitrate and nickel nitrate in de-ionised water to provide a sub-0.30 molar aqueous solution of copper nitrate and nickel nitrate together in the ratio required; providing an ammoniacal solution by adding concentrated aqueous solution of ammonia in a quantity equal to between six and ten times the quantity required to realise both a 1:6 molar ratio for Cuto ammonia and a 1:6 molar ratio for Nito ammonia; loading gamma alumina with 1 to 30% w/w of copper and nickel in a weight ratio of nickel to copper of 1:5 to 2:1 by suspending the requisite quantity of gamma alumina in said ammoniacal solution to achieve the required loading of copper and nickel; stirring the resulting gamma alumina suspension for at least 4 h at room temperature; then the volatile components evaporate under ambient conditions leaving dry loaded gamma alumina, which is calcined at a temperature of at least 260° C. for at least 30 min with a constant heating up rate; a catalyst or catalyst mixture, the catalyst or each catalyst in the catalyst mixture being obtainable by the above-mentioned process; and the use of the catalyst or catalyst mixture for the conversion of exhaust gases from an internal combustion engine into carbon dioxide, water and nitrogen.