| abstract |
In an internal combustion engine, a hydrocarbon supply valve (15) and an exhaust gas purification catalyst (13) are disposed in an engine exhaust gas passage. On the exhaust gas purification catalyst (13), platinum Pt (51) is supported, and a basic layer (53) is formed. The concentration of hydrocarbon that flows into the exhaust gas purification catalyst (13) is oscillated with an amplitude within a predetermined range and with a period within a predetermined range to thereby reduce NO X contained in exhaust gas by the exhaust gas purification catalyst (13). At this time, as the oxidation power of the exhaust gas purification catalyst (13) increases, the injection pressure of hydrocarbon from the hydrocarbon supply valve (15) is increased. |