Oxygen-vacancy mediated acidity and redox properties on WOx/Cu-doped CeO2for the removal of NOx

Acidity and redox properties of the catalyst are two crucial factors affecting the performance of NH3-SCR. Herein, we design a novel WOx/Cu-CeO2oxide catalyst in which the WOxspecies are highly dispersed on the {111}/{100}-terminated surface of Cu-doped CeO2nanospheres, which exhibits great deNOxactivity advantage and wide operating temperature window (200–400 °C, over 85% NOxconversion with a gas hourly space velocity (GHSV) of 60,000 h−1), as well as good sulfur resistance and N2selectivity. The relationship among the composition, acidity and redox properties of the WOx/Cu-CeO2catalyst is established in the NH3-SCR reaction. The combined experimental studies and spectroscopic characterization reveal that the introduction of Cu into the lattice of CeO2not only increases the surface Ce3+and oxygen vacancy concentration but also provides more sites for capture and dispersion of WOxspecies, thus mediating and improving the Lewis and Brønsted acid sites and reducibility of catalyst. XPS and DFT calculations further demonstrate that electronic interaction between WOxand Cu-doped CeO2is enhanced duo to the existence of interactions of short-range Ce-O-Cu and Ce-O-W. Moreover, the NH3-SCR reaction over WOx/Cu-CeO2may follow both Langmuir-Hinshelwood and Eley-Rideal reaction pathway according to the in situDRIFTS.