EXHAUST GAS PURIFICATION THREE-WAY CATALYST

PROBLEM TO BE SOLVED: To provide an exhaust gas purification three-way catalyst having an excellent three-way purification performance in a wide temperature window range from a low temperature region to a high temperature region without using an expensive noble metal which is a rare metal compared with a conventional three way catalyst, which is brought into contact with combustion exhaust gas containing carbon monoxide, hydrocarbons, and a nitrogen oxide generated by combustion of a fuel near the stoichiometric mixing ratio of air and a fuel to catalytically purify the three components.SOLUTION: There is provided a first catalyst which comprises (A) 1 to 20 wt.% of copper, (B) 0.1 to 10 wt.% of at least one element selected from zirconium, tin, silicon, yttrium, lanthanum, praseodymium and gadolinium and (C) γ-alumina, based on the total weight of catalyst components. There is provided a second catalyst which comprises 1 to 20 wt.% of copper and iron (provided that the atomic ratio Fe/Cu is in the range of 0.1 to 1) instead of 1 to 20 wt.% of the copper.SELECTED DRAWING: None 【課題】空気と燃料の量論混合比近傍において、燃料の燃焼によって生成する一酸化炭素、炭化水素類及び窒素酸化物を含有する燃焼排ガスを接触させて、上記３成分を接触的に浄化するための三元触媒であって、これまでの三元触媒に比べて、希少金属である高価な貴金属を用いることなく、それでいて、低温域から高温域にわたって広い温度ウィンドウ範囲ですぐれた三元浄化性能を有する排ガス浄化三元触媒を提供する。【解決手段】本発明による第１の触媒は、触媒成分の全重量に基づいて、（Ａ）銅１〜２０重量％、（Ｂ）ジルコニウム、スズ、ケイ素、イットリウム、ランタン、プラセオジム及びガドリニウムから選ばれる少なくとも１種の元素０．１〜１０重量％及び（Ｃ）γ−アルミナを含む。第２の触媒は、上記銅１〜２０重量％に代えて、銅１〜２０重量％と鉄（但し、Ｆｅ／Ｃｕ原子比は０．１〜１の範囲である。）を含む。【選択図】なし