DeNOx performance of Ag/Al(2)O(3) catalyst using simulated diesel fuel-ethanol mixture as reductant

초록

The NOx reduction activity of Ag/Al(2)O(3) catalyst has been investigated systematically, using a mixture of simulated diesel fuel (SD) and ethanol (E) as the reductant with special interest in the low temperature deNOx performance below 350 degrees C. The Ag loading and catalyst operating conditions such as C(1)/NOx and ethanol/simulated diesel fuel (E/SD) ratios have been optimized in order to achieve the maximum deNOx performance of the Ag/Al(2)O(3) catalyst. Ammonia has been identified as the most abundant reaction intermediate over the Ag/Al(2)O(3) catalyst under the optimized operating conditions. To further enhance the deNOx performance by utilizing the NH(3) formed over the Ag/Al(2)O(3) catalyst, a dual-bed reactor system has been employed with CuZSM5 catalyst in the rear bed consecutively following the front bed containing the Ag/Al(2)O(3). The NOx-to-N(2) conversion in this dual-bed system increased up to 85% from 275 to 450 degrees C, mainly due to the NH(3) oxidation to N(2) by the CuZSM5 in the rear bed. Physicochemical characterization of the Ag/Al(2)O(3) catalysts by UV-vis, TEM and EELS has indicated that both ionic and metallic Ag formed on the catalyst surface play important roles for the high deNOx performance of the present catalytic system; the ionic Ag including Ag. and Ag(delta+) is the ac