Atomic-level design of acid-base pairs in oxides for selective catalytic reduction of nitrogen oxides with ammonia.

Selective catalytic reduction of nitrogen oxides (NOx) with NH3 (NH3-SCR) poses considerable potential in the abatement of NOx emissions. However, the efficient adsorption and speedy reaction of reactants following the specific mechanism in a favorable way is still a challenge for enhancing catalysis. Herein, we propose the strategy aimed at adjusting electronic properties of Ce-Ov-W acid-base pairs through constructing oxygen vacancies on Ce/WOx, thereby fostering SCR activity. Experimental and theoretical results reveal that Ce-Ov-W acid-base pairs not only provide more Ce3+ sites for promoting the reactivity of adsorbed NO, but also accelerate the reaction between NH3 and gaseous NO owing to the generation of W5+ species with superior surface acidity, which enhance Langmuir-Hinshelwood and Eley-Rideal mechanisms, respectively. Consequently, the designed catalysts achieve over 90% NOx conversion above 250°C and exhibit higher activity than normal Ce/WO3 and V/W-TiO2 commercial catalysts, with anti-poisoning of SO2 and H2O under harsh working conditions, expecting to provide the guidance for promoting de-NOx industrial application.