DENITRIFICATION CATALYST AND METHOD FOR DENITRIFYING EXHAUST GAS

摘要

PURPOSE:To provide the catalyst capable of efficiently removing NOx in the exhaust gas of an internal combustion engine operated in a lean fuel/air ratio in a short contact time by depositing silver on activated alumina having a specific pore structure. CONSTITUTION:In this method, the pore radius and pore volume values of the activated alumina are measured by the gaseous nitrogen adsorption method, and at this time, the total pore volume of the pores having <=300Angstrom pore radii (A), the total volume of pores having 30 to 100Angstrom pore radii (B) and the total pore volume of pores having 100 to 300Angstrom pore radii (C) are controlled so as to satisfy B>=0.72A; C<=0.2A. The obtained denitrification catalyst can be used for reducing the NOx to gaseous nitrogen in a high conversion ratio and also in a short contact time even at the time of removing NOx generated by the combustion of various kinds of HC under the excess oxygen atmosphere coexisting steam.