Abstract: A catalyst for the purification of an exhaust gas emitting from a lean burn engine using gasoline as a fuel thereof and a method for the purification are provided. The catalyst has deposited on an inert carrier a mixture of a catalytically active component comprising palladium, an oxide of at least one alkali metal selected from the group consisting of potassium, sodium, rubidium, and cesium, and an oxide of at least one iron family metal selected from the group consisting of cobalt, nickel, and iron with a refractory inorganic oxide. This catalyst is used either alone or in combination with an oxidizing catalyst or a three-way catalyst for the purification of the exhaust gas from the lean burn engine using gasoline as a fuel thereof.

Abstract: The removal of nitrogen oxides from an exhaust gas is accomplished by a method which comprises causing the exhaust gas in an oxidizing atmosphere to contact a catalyst comprising a refractory inorganic oxide and catalytically active components, the components comprising 0.1 to 30 g per liter of the catalyst of at least one noble metal selected from the group consisting of Pt, Pd, Rh, and Ru or a compound of the noble metal and 1 to 80 g per liter of the catalyst of at least one metal selected from the group consisting of Li, K, Na, Rb, Ce, Be, Mg, Ca, St, and Ba or a compound of the metal, thereby inducing the catalyst to adsorb thereon the nitrogen oxides in the exhaust gas and, subsequently introducing a reducing substance intermittently into the exhaust gas thereby purifying the exhaust gas by reducing the nitrogen oxides adsorbed on the catalyst.

Abstract: An exhaust gas purifying catalyst suppressing the generation of hydrogen sulfide obtained by coating and supporting on a honeycomb carrier of a monolithic structure a catalyst composition containing (a) activated alumina supporting platinum and/or palladium in the range of 5 to 30 weight % and rhodium in the range of 1 to 20 weight %, (b) a cerium oxide and (c) activated alumina, and optionally (d) an alkali metal and/or (e) a nickel oxide.

Abstract: An exhaust gas purifying catalyst for simultaneous removal of carbon monoxide, hydrocarbons and nitrogen oxides from an exhaust gas from an internal-combustion engine, having carried on a monolithic carrier a mixture comprising a catalytically active component comprising 0.5 to 30 g of palladium, 0.1 to 50 l g of an alkaine earth metal oxide, 10 go 150 g of cerium oxide, and 0.1 to 50 g of zirconium oxide and 10 to 300 g of an activated alumina.

Abstract: A catalyst for purifying exhaust gas produced by coating honeycomb carriers of monolithic structure with a catalyst composition comprising cerium oxide particles stabilized with (a) zirconia or (b) zirconia and at least one member selected from the group consisting of yttria and calcia, refractory inorganic oxide particles, 0.02 to 2% by weight of rhodium based on said catalyst composition, and 0 to 10% by weight of at least one platinum-family metal selected from the group consisting of platinum and palladium based on said catalyst composition.

Abstract: A catalyst for purifying exhaust gas comprises a honeycomb carrier of monolithic structure and a coating layer deposited on the honeycomb carrier and formed with a catalyst composition containing a refractory inorganic oxide in the form of particles possessing and average particle diameter in the range of 0.5 to 20 microns, which refractory inorganic oxide has platinum and/or palladium and rhodium deposited thereon in high concentrations. This catalyst is produced by coating the honeycomb carrier with an aqueous slurry containing the catalyst composition and calcining the coated carrier.

Abstract: A coating method comprising coating a metal having a metal oxide film with a refractory metal oxide using an aqueous slurry containing said refractory metal oxide, which is characterized in that said refractory metal oxide has an average particle diameter ranging from 0.7-3 microns.

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.