Abstract: A catalyst composition comprises a carrier having a refractory metal oxide support coating thereon and a catalytic platinum group metal dispersed on the support coating. A major portion of the support coating is comprised of a conventional, first metal oxide such as stabilized gamma alumina and a minor portion is provided by a macroporous, second metal oxide such as cordierite. The second metal oxide is conveniently provided by comminuting finished catalyst production scrap. In the method of the invention particles of the first metal oxide are combined with particles of the second metal oxide to form the coating.

Abstract: Three-way catalysts containing rhodium, rare earth oxide and platinum and/or palladium of improved durability, when subjected to exhaust gases containing excess oxygen, are formed, when the rhodium is segregated from the rare earth oxide, thereby preventing undesirable interactions between the rhodium and are earth oxide. The efficiency of the catalyst is optimized when the rhodium has an initial average particle size ranging from about 35 to about 80 .ANG. in diameter.

Abstract: The invention relates to improved catalytic compositions for controlling gaseous contaminants from the combustion of carbonaceous fuels and, in particular, to three-way catalysts having improved ability to convert unburnt hydrocarbons, carbon monoxide and nitrogen oxides to less harmful forms in the presence of excess oxygen.