CATALYST FOR PURIFICATION OF EXHAUST GAS, STRUCTURAL BODY COATED WITH THE CATALYST AND METHOD FOR PURIFYING EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To provide a catalyst and purifying method to efficiently remove NOx in lean burn exhaust gas. SOLUTION: This catalyst for purification of exhaust gas is obtd. by incorporating silver and 0.01 to 1.5wt.% alkali metal on an alumina carrier having a porous structure with the relation of pore radius and pore volume described below. The sum pore volume X of pores having <=300Å pore radius, the sum pore volume Y of pores having the pore radius between >=25Å and <100Å, and the sum volume Z of pores having the pore radius between >=100Å and <=300Å satisfy that Y is >=70% of X, Z is <=20% of X. The structural body coated with a catalyst for purification of exhaust gas is obtd. by applying the catalyst on a monolithic supporting body comprising a refractory material having lots of through-holes in such a manner that at least the inner surfaces of through-holes are coated with the catalyst.