EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine which is configured so as to assure a high removal ratio of NOx based on the principle found that oxygen poisoning on surface of a platinum, i.e. surface of precious metals governs the removal ratio of NOx.

SOLUTION: The device employs alumina of which basic point exists on surface of a carrier as a catalyst carrier of an exhaust gas cleaning catalyst 11 for removing NOx under lean air fuel ratio. It suspends and holds on the surface of the alumina by dispersing the platinum without forming a layer of an NOx absorbing agent capable of absorbing the NOx. It temporarily switches from lean condition to rich condition the air fuel ratio of exhaust gas which flows into the exhaust gas cleaning catalyst 11 prior to the entire surface of the platinum is subjected to the oxygen poisoning.

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