REDUCING COKING OVER AG/AL2O3 HC-SCR CATALYST

摘要

The present invention relates to a method of reducing coking over a AgZAl2O3 hydrocarbon selective catalytic reduction catalyst in an exhaust stream of a lean burn internal combustion engine, the exhaust stream comprising hydrocarbon and NOx. The method comprises controlling the hydrocarbon to molar NOx ratio of the exhaust stream so as to be within certain limits at certain temperatures. An exhaust system for a lean burn engine suited to the above method, and a lean burn internal combustion engine, or a vehicle or stationary power source comprising such an exhaust system are also disclosed.