Patent ID: 6047542
Filing Date: 2000-04-11
Classification: B01D,F01N,F02B,F02D,Y02T

Abstract:
A method for purifying an exhaust gas of an engine having a plurality of cylinders divided into first and second cylinder groups, the method comprising:making an exhaust gas air-fuel ratio of the exhaust gas of the first cylinder group rich, and introducing the exhaust gas to an NH.sub.3 synthesizing catalyst to synthesize NH.sub.3, the NH.sub.3 synthesizing catalyst synthesizing NH.sub.3 from NO.sub.x in the NH.sub.3 synthesizing catalyst when the exhaust gas air-fuel ratio of the inflowing exhaust gas is rich;introducing the exhaust gas of the first cylinder group including NH.sub.3 and the exhaust gas of the second cylinder group including NO.sub.x, together, to an exhaust gas purifying catalyst; andcontrolling an amount of NO.sub.x included in the exhaust gas of the second cylinder group and to be introduced to the exhaust gas purifying catalyst to prevent the NO.sub.x amount from being larger than a NO.sub.x amount which can be reduced by the NH.sub.3 included in the exhaust gas of the first cylinder group and to be introduced to the exhaust gas purifying catalyst,wherein, on the exhaust gas purifying catalyst, the inflowing NO.sub.x is reduced by the inflowing NH.sub.3.