Promotion effect of tungsten on the activity of Pt/HZSM-5 for H2-SCR

Pt/HZSM-5 modified by W was studied in the selective catalytic reduction of NOx by hydrogen (H-2-SCR). A maximum NOx conversion of 91.1% with N-2 selectivity of 74.2% was achieved over 0.1 wt.%Pt-1 wt.%W/HZSM-5 at 110 degrees C for the feed gas mixture 910 ppm NO, 90 ppm NO2, 5000 ppm H-2, 10% O-2 in N-2 at gas hourly space velocity 36,000 h(-1). It was found that the interaction between Pt and W is favorable for Pt presenting metallic state in the catalyst. Due to the strong interaction, the dissociation of NO and H-2 on Pt was significantly accelerated and the formation of unfavorable nitrate species was effectively suppressed. As a consequence, the H-2-SCR activity and N-2 selectivity were greatly promoted by W doping the Pt/HZSM-5 catalysts. (C) 2014 Elsevier B.V. All rights reserved.