REMOVAL OF NITROGEN OXIDES FROM DIESEL ENGINE EXHAUST GASES BY USING TEMPERATURE CONTROL PRE-CATALYSTS FOR FEEDING NO2 ACCORDING TO REQUIREMENTS

摘要

PROBLEM TO BE SOLVED: To provide a removal of nitrogen oxides from diesel engine exhaust gases by using temperature control pre-catalysts for feeding NOaccording to requirements.SOLUTION: According to the exhaust gas restriction value according to the future legal requirements for diesel vehicles in Europe, North America and Japan, it is required not only to remove particles but also to remove (deNOx) nitrogen oxides effectively from exhaust gases. An "active SCR process" is a preferable method for that requirements. The nitrogen oxide conversion to be achieved by that process is enhanced especially in the case where the optimum ratio NO/NOof preferably 0.5 is set upstream of the SCR catalyst. Here is proposed a process for solving the problem at the time when the NOis fed according to the requirements, by the temperature control of a pre-catalyst to be separated from the operational state of the engine.