Patent ID: 7572422

Claim:
An exhaust gas purifying method for a vehicle, comprising: providing an exhaust gas purifying system for the vehicle, the exhaust gas purifying system including a methane removal catalyst for accelerating oxidation of methane into hydrogen and carbon monoxide by an oxidizing agent comprising oxygen, the methane removal catalyst, comprising: a first catalytic ingredient including at least one of rhodium, platinum and palladium, wherein an oxygen excessive rate ζ of exhaust gas introduced to a region where the methane removal catalyst is disposed is set in a range from 50% to 98%, the oxygen excessive rate ζ being defined by a following formula (1): ζ = C O ⁢ ⁢ 2 C CH ⁢ ⁢ 4 × 2 + C H ⁢ ⁢ 2 × 0.5 × 100 ( 1 ) where C O2 is a concentration of oxygen, C CH4 is a concentration of methane, and C H2 is a concentration of hydrogen, and wherein a temperature of the exhaust gas introduced to the methane removal catalyst is controlled in a range from 200° C. to 600° C.