PURIFICATION OF WASTE GAS

摘要

PROBLEM TO BE SOLVED: To provide a method for purifying waste gas by which NOx of a low conc. in waste combustion gas after burning can be removed with high efficiency and high reliability and superior durability is ensured. SOLUTION: Waste combustion gas from an internal combustion engine operated in a lean air-fuel ratio is brought into contact with a catalyst-contg. layer and NOx is removed with kerosene or gasoline as a reducing agent. The catalyst contained in the catalyst-contg. layer is a catalyst layer consisting of alumina and silver or a catalyst coated structure obtd. by coating the inner surfaces of at least through holes in a substrate having a monolithic structure made of a refractory material having many through holes with a catalyst consisting of alumina and silver. The alumina has a porous structure in which the relation between pore radius and pore diameter measured by a gaseous nitrogen adsorption method represents a specified value.