Insight into copper-cerium catalysts with different Cu valence states for CO-SCR and in-situ DRIFTS study on reaction mechanism

Abstract

Copper-cerium catalysts have received extensive attention for their excellent catalytic performance in the field of NO reduction with CO. In this work, Cu+-Ce and Cu2+-Ce systems were designed to examine the catalytic potential of Cu+ and Cu2+. A series of catalysts were characterized by XRD, BET, HRTEM, EDS, H2-TPR, Raman, XPS and in-situ DRIFTS in different NO + CO atmospheres. Cu+-Ce catalyst possesses a large amount of Cu+ that can promote the synergy between Cu+ and Ce4+ and adsorb CO to form Cu+-CO species consuming more active oxygen, thus generating more oxygen vacancies than Cu2+-Ce, which improve the catalytic performance of Cu+-Ce catalyst at low temperatures. In different NO + CO atmospheres, Cu+-Ce catalyst always maintains better catalytic performance to make an excellent universal applicability. In-situ DRIFTS in different NO + CO atmospheres provided evidence to confirm that oxygen vacancy is indeed active site for decomposing NO. And it also demonstrated that the CuCe/CuCe-S (Cu2+-Ce system) and CuCe/Ce-S (Cu+-Ce system) catalysts are dominated by L-H mechanism with different CO adsorption behavior at low temperatures.