| 摘要 |
PROBLEM TO BE SOLVED: To avoid as much as possible that a selection reduction type catalyst is fallen into a sulfur-poisoned state, and NOx purification performance is lowered, in an exhaust system of an internal combustion engine having the selection reduction type NOx catalyst in an exhaust passage, and a front stage catalyst having a characteristic for occluding or adsorbing a sulfur component at its upstream side.SOLUTION: In the case that an ammonia amount which is estimated to be adsorbed to a selection reduction type NOx catalyst is smaller than a prescribed amount when it is determined that an execution condition of restoration processing for eliminating a sulfur oxide which is occluded or adsorbed to a front stage catalyst by raising a temperature of the front stage catalyst is established, an exhaust system of an internal combustion engine increases an ammonia adsorption amount to at least a prescribed amount by supplying ammonia to the selection reduction type NOx catalyst, and after that, executes the restoration processing.SELECTED DRAWING: Figure 3 |
