Tungsten promoted HZSM-5 in the SCR of NO by acetylene

The performance of 6% W/HZSM-5 catalyst in the SCR of NO by C2H2, C3H6 and CH4 was compared. Contrary to the low selectivity of C3H6 in NO reduction and the high temperature required by CH4 for activation, high and steady NO conversion to N2 (89%) was achieved at 350 °C when C2H2 was used as reductant with a feed of 1600 ppm of NO, 800 ppm of C2H2, 10% of O2 in He. It was found that tungsten dispersed on HZSM-5 has a synergistic effect with protons in the C2H2-SCR of NO. Tungsten incorporation into HZSM-5 significantly accelerated the NO oxidation to NO2 and enlarged strong adsorption of NOx on the catalyst surface, and thus considerably enhanced the aimed reaction. For the C2H2-SCR of NO carried out over the 6% W/HZSM-5 catalyst, carbonous species containing a carbonyl group were active species responsible for the aimed reaction, which involves the reduction of bidentate and bridging nitrate species formed on the catalyst under the reaction conditions.