Acidified SiO₂ Supported Fe-based Bimetal Oxide Catalyst with Resistance to High-Level Alkali Poisoning for CO Selective Catalytic Reduction of NO Removal of NO_x

Catalyst deactivation deduced by alkali metals remains an austere challenge for CO selective catalytic reduction of NO (CO-SCR). Herein, the acidified SiO₂ supported Fe-based bimetal oxide catalyst was synthesized after active component screening and carrier acidification. The obtained FeCu-H catalyst exhibited excellent resistance to high-level alkali poisoning, even at low temperatures, with 78% NO conversion and 83% CO conversion achieved under 150 °C and a 1:1 molar ratio of Na to active metals. Characterizations and density functional theory (DFT) simulations revealed that the deactivation mechanism of CO-SCR catalysts by alkali metals can be ascribed to the deteriorated physicochemical properties, including crystallinity, specific surface area and pore structure, proportion of high-valence metals, NO adsorption and activation capacity, formation of oxygen vacancies, quantity of acid sites, and reducibility. Notably, the acidified carrier exhibited remarkable mitigation of these undesirable effects, thereby enhancing the CO-SCR activity. Our findings provide an inspirational strategy for developing reliable alkali-resistant SCR catalysts.