MnyCo3−yOx bimetallic oxide prepared by ultrasonic technology for significantly improved catalytic performance in the reduction of NOx with NH3

Abstract

NOx emission is a major environmental issue. Selective catalytic reduction (SCR) is the most effective method for the conversion of NOx in flue gases to harmless N2 and H2O. In this work, a series of Mn-Co mixed metal oxides, MnyCo3−yOx, are intentionally prepared by an ultrasonic technology followed by a hydrothermal treatment, and their denitration (de-NOx) performances are evaluated by the SCR reaction in the presence of NH3. The results show that the SCR de-NOx performance of MnyCo3−yOx is significantly improved compared with single metal oxide (MnOx or CoOx). The reason can be ascribed to a strong interaction between MnOx and CoOx, which reduces the crystallinity of MnyCo3−yOx catalysts, increases the specific surface area, builds the redox cycle of Co3+ + Mn3+ ↔ Co2+ + Mn4+, improves the reducibility, enhances the surface acid sites, accelerates the reaction between the adsorbed NOx species and the coordinated NH3 bound to the Lewis acid site, resulting in a significant improvement in the SCR de-NOx performance. The work provides us with a thought to improve the de-NOx performance by building a strong interaction between catalyst components.