Construction of bimetallic InIr/H-Beta catalyst with enhanced activity and selectivity in selective catalytic reduction of nitrogen oxide with methane

H-Beta supported InO x -IrO x dual-function active sites with abundant acid sites are designed. • Synergy of InO x -IrO x regulates surface redox properties and InO⁺ species generation. • InO⁺ species and acid sites facilitates NO conversion while IrO x sites promote CH₄ activation. • IrIn/H-Beta demonstrates superior CH 4 -SCR performance. In the field of selective catalytic reduction of nitrogen oxides with methane (CH 4 -SCR), achieving a balance between high CH 4 -SCR selectivity and high CH 4 activation ability remains challenging. Herein, InO x -IrO x dual-function active sites anchored on the H-Beta zeolite with abundant acid sites are rationally designed. The InO x -IrO x bimetallic oxide structures and the confinement effect of the zeolite framework effectively suppress the migration and sintering of IrO x species, while the electron transfer between In and Ir facilitates the formation of Ir-O-In bond and the generation of InO⁺ species. The In sites, together with the acid sites of H-Beta, assist the conversion of NO into NO 3 - and NO⁺ species, while the CH 4 is predominantly dissociated on Ir sites to form In-CH 3 species via the Ir-O-In bond. These In-CH 3 species react with nitrate species on adjacent InO⁺ sites to form reactive intermediates such as CH 3 NO 2 , which further interact with NO⁺ to produce N 2 , CO 2 , and H 2 O. Owing to the dual functionality of InO x -IrO x active sites, the as-designed IrIn/H-Beta simultaneously achieves superior performance of 81% NO x conversion and 100% CH 4 conversion at 500°C under a gas velocity of 120,000 mL g -1 h -1 . Such proposed dual-function bimetallic catalyst design strategy demonstrates potential for developing a catalyst with high activity and high selectivity in CH 4 -SCR reactions. The as-proposed dual-function bimetallic IrIn/H-Beta catalyst demonstrates high activity and high selectivity in CH 4 -SCR reactions. Download: Download high-res image (193KB) Download: Download full-size image