Abstract: An NO.sub.x absorbent (19) which absorbs NO.sub.x when an air-fuel ratio of an inflowing exhaust gas is lean, while releases the absorbed NO.sub.x when lowering an oxygen concentration in the inflowing exhaust gas, is arranged in an exhaust passage of an internal combustion engine. An SO.sub.x absorbent (18) which absorbs SO.sub.x when the air-fuel ratio of the inflowing exhaust gas is lean, while releases the absorbed SO.sub.x when the air-fuel ratio of the inflowing exhaust gas is made rich is arranged in the exhaust passage on the upstream side of the NO.sub.x absorbent (19). When the lean air-fuel mixture is burned, the SO.sub.x is absorbed into the SO.sub.x absorbent (18) and, at the same time, the NO.sub.x is absorbed into the NO.sub.x absorbent (19), and when the air-fuel ratio of the air-fuel mixture is switched from lean to rich, SO.sub.x is released from the SO.sub.x absorbent (18), and NO.sub.x is released from the SO.sub.x absorbent (19 ).

Abstract: An engine comprising an exhaust passage having therein a NO.sub.x absorbent which absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent becomes the stoichiometric air-fuel ratio or rich. A catalyst having an O.sub.2 storage function is arranged in the exhaust passage downstream of the NO.sub.x absorbent. When NO.sub.x is to be released from the NO.sub.x absorbent, the air-fuel ratio of the exhaust gas is made rich to an extent such that the amount of unburned HC and CO is excessive beyond an amount necessary to reduce the whole NO.sub.x.

Abstract: In an exhaust purification apparatus of an internal combustion engine having an NOx absorption and release material in an exhaust conduit, a heater is provided close to the NOx absorption and release material. When an NOx absorption operation continues for a predetermined period, the heater is switched on to raise the temperature of the NOx absorption and release material above a predetermined temperature, for example, 500.degree. C. When the temperature of the NOx absorption and release material is high, the NOx absorption and release material releases absorbed NOx and is regenerated.