Patent ID: 6596247
Filing Date: 2003-07-22
Classification: B01D,B01J

Abstract:
A method for purifying exhaust from an engine, comprising:operating said engine under lean burn conditions; and reducing nitrogen oxides in an exhaust gas passage with a catalyst consisting of: a porous supporter of inorganic oxides; and supporting components consisting of compounds of: 2.5-27 wt. % of at least one alkali metal, 1-8 wt. % titanium, at least one noble metal selected from the group consisting of 0.05-0.3 wt. % rhodium, 0.5-15 wt. % palladium, and 0.5-3 wt. % platinum, and optionally magnesium of 1-40% as a weight ratio of magnesium to said at least one alkali metal and magnesium on a surface of said porous supporter, wherein the weight percent of the supporting components is based upon 100 weight percent of the porous supporter.