Patent ID: 8501133

Claim:
A method of treating exhaust gases containing nitrogen monoxide, carbon, and carbon compounds comprising: preparing a catalyst by the steps of: forming a lower coat layer having a thickness of 20 to 100 μm by coating the surface of a substrate with a slurry of a porous inorganic compound, followed by drying; preparing a colloidal solution of one or more precious metals; allowing the one or more precious metals to be supported on a porous inorganic compound by using the colloidal solution; preparing a slurry of the porous inorganic compound having the one or more precious metals supported thereon; and forming an upper coat layer having a thickness of 4 to 30 μm, which is to be the top surface of the catalyst, by coating the surface of the lower coat layer with the slurry, followed by drying, wherein a population of particles that have a multi-peak particle size distribution is used as the porous inorganic compound; and exposing the exhaust gases to a catalyst in a manner sufficient to catalyze reduction of the exhaust gases.