METHOD FOR CATALYTIC REDUCTION OF NITROGEN OXIDES

PROBLEM TO BE SOLVED: To stably, efficiently and catalytically reduce nitrogen oxides even in the coexistence of oxygen, sulfur oxides or moisture without using a large quantity of a reducing agent and generating a nitrogen-containing compd. such as ammonia, amine or hydrogen cyanide as a byproduct in the catalytic reduction of nitrogen oxides using hydrocarbon as a reducing agent. SOLUTION: In a method for catalytically reducing nitrogen oxides contained in exhaust gas by using hydrocarbon as a reducing agent in the presence of a catalyst, in a first stage, exhaust gas containing hydrocarbon along with nitrogen oxides is brought into contact with a catalyst selected from silver, silver oxide and silver aluminate and, in a second stage, the exhaust gas is brought into contact with a catalyst selected from alumina, silica/alumina, zirconia, and titania.