Insights into the superior resistance of In-Co3O4-Ga2O3/H-Beta to SO2 and H2O in the selective catalytic reduction of NOx by CH4

The existence of sulfur dioxide and water vapor in the flue gas generated from waste-to-energy stations could lead to catalyst deactivation , which has adverse effects on NO x removal. It is thus particularly important to study the reaction mechanism of catalyst resistance to poisoning. Herein, we report the mechanism of In-Co 3 O 4 -Ga 2 O 3 /H-Beta catalyst to SO 2 and H 2 O resistance in the selective catalytic reduction (SCR) of NO x by CH 4 . The catalyst could achieve 74.6% NO x removal efficiency in the presence of 100 ppm SO 2 and 5% H 2 O. In this catalyst, Co 3 O 4 is attributed to enhancing the reversible poisoning of SO 2 and CH 4 activation and increasing the number of Brønsted acid sites by decomposing H 2 O. However, the InO + active center was still eroded by a small amount of water vapor, leading to a reduction in NO x removal efficiency. The addition of Ga 2 O 3 primarily provided an important intermediate NO 2 for CH 4 -SCR reaction and reduced the aggregates of Co 3 O 4 to increase the exposure of indium sites, and could reduce a part of SO 2 to S 2− . This study provides a good candidate for preparing catalysts with superior resistance towards SO 2 and H 2 O for CH 4 -SCR.