Balancing redox and acidic properties for optimizing catalytic performance of SCR catalysts: A case study of nanopolyhedron CeOx-supported WOx

For the selective catalytic reduction of NOx with NH3 (NH3-SCR) reaction, how to precisely adjust the reducibility and surface acidity over SCR catalysts remains a fundamental challenge. Here, a very facile and effective way, the addition of WOx species using an incipient wetness impregnation method, to balance the redox and acidic properties of CeOx for optimizing its SCR performance was proposed. Especially, nanopolyhedron CeOx with predominately exposed (111) facet was prepared as the support of WyCe catalysts. As an effective surface modifier, the WOx species could not only suppress the over-oxidation of NH3 over CeOx by partially covering oxygen vacancies, but also supply abundant Bronsted and Lewis acid sites, which stemmed from W-O, W-O-W, Ce-O-W bonds and electronically deficient unsaturated Cen(+), Wn(+) cations, respectively. As a result, the SCR activity and N-2 selectivity of WyCe catalysts were significantly improved at the same time, through the balance between the redox and acidic properties. The above results might open a new avenue for the design and preparation of more efficient SCR catalysts.