| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce the amount of sulfate emitted into the atmosphere while maintaining the amount of a reducing agent required to reduce the amount of stored sulfur by reducing the sulfur stored in an NOX catalyst, to a small amount. <P>SOLUTION: When SOX in the NOX catalyst 81 is to be reduced to decrease the accumulated amount of SOX, a selector valve 61 is held into a weak forward flow position where a greater part of exhaust gas exhausted from an internal combustion engine flows out of an inflow port 62 into an exhaust gas exhaust pipe 64 directly through an outflow port 63, that is, makes a detour around the NOX catalyst 81, and a slight fixed quantity of remaining exhaust gas flows into an annular exhaust pipe 67 and flows through inside the NOX catalyst 81. A catalyst 76 with oxidation capacity is arranged in the exhaust gas exhaust pipe 64, and the oxidation capacity of the catalyst 76 is set lower than that of the NOX catalyst 81. As a result, SO<SB>2</SB>, H<SB>2</SB>S exhausted from the NOX catalyst 81 is hardly oxidized by the sulfate SO<SB>3</SB>in the catalyst 76. <P>COPYRIGHT: (C)2004,JPO</p> |
