Insights into the precursor effect on the surface structure of γ-Al2O3 and NO + CO catalytic performance of CO-pretreated CuO/MnOx/γ-Al2O3 catalysts

NO reduction by CO was investigated over CO-pretreated CuO/MnOx/gamma-Al2O3 catalysts with different metal precursors (nitrate and acetate). It was found that the catalyst prepared from acetate salts (Cu/Mn/Al-A) exhibited significantly higher activity than counterpart catalyst from nitrate precursors (Cu/Mn/Al-N). XRD, XPS and in situ DRIFT were carried out to approach the nature for the different catalytic performance. For both catalysts, copper mainly existed as CuO, but the status of manganese oxide was markedly different. Mn(IV) was predominant in Cu/Mn/Al-N and Mn(III) was enriched in Cu/Mn/Al-A. As a result, different dispersion behaviors of manganese oxide on gamma-Al2O3 were displayed, which induced inconsistent Cu-Mn contact. The catalyst obtained from acetate precursor exhibited enriched Cu-Mn contact and thus more Cu+-square-Mn3+/2+ entities would be produced after CO pretreatment, leading to promoted NO dissociation and favorable performance in NO reduction by CO. The present study sheds light on the effective tuning of Cu-O-Mn interfacial sites in CuO/MnOx/gamma-Al2O3 via modulating the dispersion behaviors of surface components. (C) 2019 Elsevier Inc. All rights reserved.