Influence of CeO2 morphology on WO3/CeO2 catalyzed NO selective catalytic reduction by NH3

Abstract

WO3/CeO2 catalysts with different support morphologies were fabricated by incipient wetness technique and applied to selective catalytic reduction of NO by NH3 (NH3-SCR). WO3/CeO2 rod (WCR) displayed higher catalytic activity and resistance to SO2 and H2O compared with WO3/CeO2 polyhedron (WCP) and WO3/CeO2 cube (WCC). N2-BET, XRD, Raman, H2-TPR, TEM, HRTEM, NH3-TPD, XPS and in situ DRIFTS were conducted to investigate the physicochemical properties of the catalysts and the adsorption of NH3 and NOx species on the catalytic surface. These characterization results demonstrated that the larger BET surface area, the smaller CeO2 particle size, the higher surface acidity, the more oxygen defects, the better redox performance, and the higher Ce3+ and Oα ratios of the catalysts played critical functions in obtaining more outstanding NH3-SCR catalytic performance. All of these characterization results were also closely related to the CeO2 morphology. The results of the in situ DRIFTS showed that the WCR had the highest intensities of the adsorbed NOx and NH3 species among these three catalysts. The reactions between adsorbed species attributed to NOx and NH3 on the catalyst surface can also be a key factor in the NH3-SCR catalytic performance enhancement.