Enhancement of the catalytic performance of CrOx-WO3 catalyst through FeOx modification for selective catalytic reduction of NOx with NH3

In this study, the influence of FeOx modification on the deNO(x) performances and physicochemical properties of the CrOx-WO3 composites was investigated. The individual FeOx-WO3 and CrOx-WO3 catalysts exhibited poor catalytic activity, achieving a NOx conversion of similar to 91 % solely at 300 degrees C. At a fixed Cr/Fe molar ratio of 1/1, the optimized catalyst exhibited superior SCR activity, achieving over 90 % NOx conversion at a temperature range of 250-450 degrees C. This satisfactory catalytic activity was attributed to an increase in the surface acid sites of the catalyst caused by interactions between the added FeOx and CrOx-WO3. The increased acid sites facilitated the adsorption of NH3 and provided a sufficient supply of reductant for the subsequent activation stage. Furthermore, compared with FeW, the moderate oxidative ability of the FeOx-modified CrOx-WO3 composite enabled the efficient activation of reactants, thereby endowing it with a wide operational temperature range. During the SCR reactions, both CrOx and WO3 provided acid sites for the adsorption of NH3. The Eley-Rideal mechanism dominated the process, and the dehydrogenation of the adsorbed ammonia species was identified as the critical step. Finally, the FeOx-CrOx-WO3 composite exhibited a relatively high sensitivity to SO2, highlighting the need for further modification to enhance its practical applicability.