Abstract: A catalyst composition suitable for three-way conversion of internal combustion engine, e.g., automobile gasoline engine, exhaust gases includes a catalytic material disposed in on a carrier. The catalytic material contains a co-formed (e.g., co-precipitated) rare earth oxide-zirconia support on which a first rhodium catalytic component is dispersed, and an alumina support having a platinum catalytic component dispersed thereon. The catalytic material may also include a second rhodium catalytic component dispersed on the alumina support bearing the platinum or a second alumina support. The catalytic material may be disposed as a catalytic coating directly on the carrier or upon an optional undercoat which is disposed on the carrier and which includes alumina and optionally, ceria and/or, iron oxide.

Abstract: A catalyst composition includes a zirconia support on which is dispersed a limited amount of ceria to provide a zirconia/dispersed ceria support, and a rhodium catalytic component. The ceria content of the zirconia support does not exceed about fifteen percent by weight based on the combined weight of ceria plus zirconia. The resultant catalyst composition enhances the efficiency of three-way conversion catalyst systems in which it is employed, possibly by promoting the water gas shift reaction and the steam reforming of hydrocarbon. The rhodium on zirconia/dispersed ceria support may be combined with a catalytically effective amount of a platinum catalytic component to provide an effective three-way conversion catalyst.

Abstract: Molecular sieve catalysts, such as alumino-silicate zeolites, used in hydrocarbon conversion and separation processes, are restored after their recommended use-cycle service, by novel methods of regeneration and metal redispersion, or rejuvenation.An additive compound is injected into the catalyst during regeneration, or coke removal. The additive is of a molecular diameter large enough to prevent the additive from being captured by a cell of the catalyst, and is preferably of a pH which promotes adsorption of the additive onto the zeolite material.Metal-coated zeolite catalysts are rejuvenated, preferably after regeneration, by injecting a halogen compound followed by the above additive compound, and then heating the catalyst to a high temperature. This procedure is effective in re-dispersing metal agglomerates uniformly throughout the catalyst to restore the original metal coating.