CATALYST LAYER FOR CLEANING EXHAUST GAS, CATALYST-COATED STRUCTURE FOR CLEANING EXHAUST GAS AND METHOD FOR CLEANING EXHAUST GAS BY USING BOTH

摘要

PROBLEM TO BE SOLVED: To provide a catalyst layer for cleaning exhaust gas which can efficiently remove NOx in the exhaust gas from a lean combustion type internal combustion engine where natural gas is used as fuel and to provide a catalyst- coated structure for cleaning exhaust gas and a method for cleaning exhaust gas by using both of the catalyst layer and catalyst-coated structure. SOLUTION: The catalyst layer consists of a mixture of the first catalyst containing an acidic carrier and a platinum metal and the second catalyst containing palladium and zeolite. The first catalyst is obtained by depositing at least one platinum metal selected from the group consisting of Pt, Rh and Ru on at least one acidic carrier selected from the group consisting of alumina, silica-alumina, titania, zirconia, sulfuric acid-treated titania, sulfuric acid-treated zirconia and zeolite.