Reaction and deactivation mechanisms of a CeIn/HBEA catalyst with dual active sites for selective catalytic reduction of NOx by CH4

Methane selective catalytic reduction (CH 4 -SCR) technology has shown promise for controlling NO x emissions from natural gas generator sets. This study presents a highly efficient Ce 30 In 15 /HBEA catalyst featuring dual active sites, Al-O – (InO + )-Si site for CH 4 activation and ceria oxygen vacancy (Ce 3+ -□) site for NO x activation. However, the CH 4 -SCR activity of this catalyst decreased in the presence of H 2 O, SO 2 , C 3 H 6 , and CO 2 . The inhibitory effects on CH 4 -SCR activity followed by the sequence: H 2 O > SO 2 > C 3 H 6 > CO 2 . In particular, H 2 O combined with Al-O – (InO + )-Si to form inactive In(OH) 3-z z+ species and occupied Ce 3+ -□, preventing Ce 4+ -NO 3 – /NO 2 – formation. In/Ce sulfate formation via the reaction between SO 2 and In/Ce active sites hindered CH 4 and NO x adsorption and activation. The formed carbon deposits covered the active sites on the catalyst surface due to incomplete C 3 H 6 oxidation . In comparison, the dual active sites were almost unaffected by CO 2 . Overall, this study provides a basis for the rational design of novel catalysts for CH 4 -SCR.