Abstract: A reaction comprising the oxidation of carbon monoxide to carbon dioxide, eg in vehicle exhausts, employs a catalyst composed of metal oxide, eg. ceria, particles among which are uniformly incorporated noble metal particles, the particles having such a high interaction that, without hydrogen reduction pre-treatment, the catalyst exhibits the formation of anionic vacancies on the metal oxide surface at a temperature lower than does the corresponding catalyst prepared by impregnation. The catalyst employed is preferably prepared by co-precipitation.

Abstract: A catalyst comprising catalytic material on a support, the catalytic material comprising platinum, and the support consisting essentially of at least one of zirconia, tin oxide and titania, which catalyst contains less than 400 ppm of chlorine atoms based on the weight of catalytic material plus support, is useful for reducing the content of nitrogen oxides in a flue gas containing them, oxygen and 5-3000 ppm by volume of sulphur dioxide by admixing ammonia with the flue gas and passing the mixture over the catalyst.

Abstract: A reaction comprising the oxidation of carbon monoxide to carbon dioxide, eg in vehicle exhausts, employs a catalyst composed of metal oxide, eg ceria, particles among which are uniformly incorporated noble metal particles, the particles having such a high interaction that, without hydrogen reduction pre-treatment, the catalyst exhibits the formation of anionic vacancies on the metal oxide surface at a temperature lower than does the corresponding catalyst prepared by impregnation. The catalyst employed is preferably prepared by co-precipitation.