Exhaust gas purification catalyst, exhaust gas purification apparatus using the same and exhaust gas purification method

Abstract

An exhaust gas purification catalyst, which is suitable as a three way catalyst for efficiently purifying carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in exhaust gas discharged from a gasoline automobile and exhaust gas purification apparatus using the same and an exhaust gas purification method. <The upper layer> A catalyst composition having an activated metal (A), a heat resistant inorganic oxide (B) and a cerium-zirconium-type composite oxide (C) containing a pyrochlore phase in a crystal structure, wherein the activated metal (A) is rhodium. <The lower layer> A catalyst composition having an activated metal (A), a heat resistant inorganic oxide (B) and a cerium-containing oxide (C′) having a cubic crystal and/or tetragonal crystal structure as a major crystal structure, wherein the activated metal (A) is palladium, or palladium and platinum.

Dependencies are inferred from the claim text.