Abstract: A process for preparing a catalyst for cleaning exhaust gases comprising a refractory carrier composed mainly of alumina and having deposited thereon, iron oxide, cerium oxide and at least one noble metal element, which comprises impregnating said carrier with(a) an aqueous solution A prepared by adding aqueous ammonia to an aqueous solution containing a water-soluble iron salt as a material for iron and a cerium salt of an organic acid as a material for cerium to adjust the pH of the aqueous solution to 6.0-9.0, and optionally adding an ammonium salt of an organic acid, and(b) an aqueous solution B containing a compound of the noble metal element.

Abstract: A process for producing an auto exhaust gas catalyst capable of simultaneously removing hydrocarbons, carbon monoxide and nitrogen oxides, which comprises depositing on a refractory inorganic support, 0.5 to 30 g of cerium, 0 to 20 g of iron, 0 to 10 g of lanthanum, 0.005 to 0.3 g of rhodium, 0.05 to 3.0 g of platinum, 0 to 1.2 g of palladium and 0 to 0.5 g of phosphorus as elements per liter of the finished catalyst in any desired sequence.

Abstract: The present invention relates to a catalyst for purifying exhaust and waste gases which is capable of simultaneously removing nitrogen oxide, carbon monoxide and hydrocarbons from the exhaust gases, comprising supporting phosphorus, barium, rhodium and at least one member selected from the group consisting of palladium and platinum, and optionally nickel on a carrier, and a method for preparation thereof.