摘要:
A method for purifying an oxygen excess exhaust gas by catalytically reducing nitrogen oxides contained in the exhaust gas, which comprises bringing a catalyst comprising at least one noble metal supported on a carrier composed mainly of an oxide or a complex oxide of at least one metal selected from rare earth metals and metals of the group IV A of the periodic table of elements into contact the exhaust gas.
摘要:
An NOx-absorbing and reducing catalyst device (7) is disposed in an exhaust passage of an engine (1). The NOx concentration in exhaust gas flowing out of the catalyst device is detected by an NOx sensor (33). Every time the NOx concentration detected by the NOx sensor increases to a predetermined value, an electronic control unit (ECU) (30) of the engine reactivates the NOx-absorbing and reducing catalyst device (7) by operating the engine (1) at a rich air fuel ratio for a short time. The ECU (30) also detects a deviation of the output of the NOx sensor (33) on the basis of a reference value (corresponding to zero NOx concentration) and an output of the NOx sensor (33) produced when the engine is being operated in a condition where the amount of NOx discharged from the engine is small, for example, a condition where the air-fuel ratio is on the lean side and the load is low (that is, in a condition where the NOx concentration in exhaust gas reaching the NOx sensor (33) becomes substantially zero). Based on the detected deviation, the ECU (30) corrects the output of the NOx sensor (33).
摘要:
In the exhaust gas purification device of the present invention, a NO x absorbent is disposed in the exhaust gas passage of a diesel engine. At the time when NO x should be released from the NO x absorbent, a control circuit of the engine reduces the excess air ratio of the engine, and switches the combustion mode of the engine from the normal diesel combustion, in which diffusive combustion is dominant in the combustion chamber of the engine, to the combustion mode in which pre-mixture fuel combustion is dominant. By doing this, it is possible, even in a diesel engine, to reduce the excess air ratio in combustion to thereby make the air-fuel ratio of the exhaust gas lower than or equal to the stoichiometric. Thus, the regeneration of the NO x absorbent can be performed even when it is applied to a diesel engine.
摘要:
In the exhaust gas purification device of the present invention, a NO x absorbent is disposed in the exhaust gas passage of a diesel engine. At the time when NO x should be released from the NO x absorbent, a control circuit of the engine reduces the excess air ratio of the engine, and switches the combustion mode of the engine from the normal diesel combustion, in which diffusive combustion is dominant in the combustion chamber of the engine, to the combustion mode in which pre-mixture fuel combustion is dominant. By doing this, it is possible, even in a diesel engine, to reduce the excess air ratio in combustion to thereby make the air-fuel ratio of the exhaust gas lower than or equal to the stoichiometric. Thus, the regeneration of the NO x absorbent can be performed even when it is applied to a diesel engine.
摘要:
A method for purifying an oxygen excess exhaust gas by catalytically reducing nitrogen oxides contained in the exhaust gas, which comprises bringing a catalyst comprising at least one noble metal supported on a carrier composed mainly of an oxide or a complex oxide of at least one metal selected from rare earth metals and metals of the group IV A of the periodic table of elements into contact the exhaust gas.