Promoted O2 resistant performance of CO selective catalytic reduction via carbon-coated CuCoAl mixed metal oxides

Abstract

Selective removal of nitrogen oxides (CO-SCR) by CO as a reducing agent has attracted wide attention. However, it has been found that the presence of O2 in the CO+NO system can poison the catalyst, which affected the application of CO-SCR technology. In this paper, CuCoAl composite metal oxide catalysts without carbon source and carbon coating were prepared by coprecipitation method, and the denitrification activity and oxidation resistance of CO-SCR catalyst were studied. It was found that CuCoAlOx@C catalyst prepared by glucose doping had excellent antioxidant properties. When 5 vol% O2 was introduced into the reaction system, the NO conversion rate of CuCoAlOx catalyst dropped sharply, while the NO conversion rate of CuCoAlOx@C catalyst remained above 85%. First of all, glucose can not only provide carbon coating, bringing a high specific surface area (121.8 m2/g), which in turn allows the exposure of active sites and enhances the catalytic activity of the catalyst. Secondly, carbon cladding can activate O2 to O* (Oxygen Free Radical), followed by partial oxidation of CO to CO2 through the MvK mechanism, thus avoiding the direct reaction of CO with O2 to form CO2 in the presence of catalyst, and to a certain extent promoting the regeneration of oxygen vacancies and the reaction of NO+CO to enhance the antioxidant performance. Thirdly, this study found that carbon-coated composite metal oxides provide a new way to improve the anti-O2 poisoning performance of CO-SCR catalysts.