摘要
A highly effective Ag-A_(2)O_(3) catalyst was pre-pared using the in-situ sol-gel method,and characterized by surface area using nitrogen adsorption,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)techniques.The catalyst performance was tested on a real lean-burn gasoline engine.Only unburned hydrocarbons and carbon monoxide in the exhaust were directly used as reductant(without any external reductant),the maximum NO_(x) conversion could only reach 40% at 450°C.When an external reductant,ethanol was added,the average NO_(x) con-version was greater than 60%.At exhaust gas temperature range of 350-500°C,the maximum NO_(x) conversion reached about 90%.CO and HC could be efficiently oxidized with Pt-_(2)O_(3) oxidation catalyst placed at the end of SCR converter.However,NOx conversion drastically decreased because of the oxidation of some intermediates to NOx again.The possible reaction mechanism was proposed as two typical processes,nitration,and reduction in HC-SCR over Ag-Al_(2)O_(3).
基金
This work was financially supported by the National Natural Science foundation of China(Grant Nos.20507012 and 20437010)
the National High-Tech Research and Development(863)Program of China(Grant No.2003AA642030)。
