Abstract
A highly effective Ag-AlO catalyst was prepared using the 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 conversion could only reach 40% at 450?C. When an external reductant, ethanol was added, the average NO conversion was greater than 60%. At exhaust gas temperature range of 350 500?C, the maximum NO conversion reached about 90%. CO and HC could be efficiently oxidized with Pt-AO oxidation catalyst placed at the end of SCR converter. However, NO conversion drastically decreased because of the oxidation of some intermediates to NO again. The possible reaction mechanism was proposed as two typical processes, nitration, and reduction in HC-SCR over Ag-AlO.
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