NO reduction by CO over copper catalyst supported on mixed CeO2 and Fe2O3: Catalyst design and activity test

Copper catalysts supported on co-synthesised Fe2O3 and CeO2 mixed metal oxide support (Cu/CeO2-Fe2O3, Cu/CF for short, CF as the support) were prepared for NO reduction by CO. Cu/CF catalysts showed better catalytic performance at 100-200 degrees C than samples of Cu/CeO2 and Cu/Fe2O3 which were supported on single metal oxide. The interaction of Fe and Ce could enhance the catalytic activity. The catalysts were characterized by N-2 adsorption, TEM, XRD, Raman, XPS, H-2-TPR, EPR, and in situ DRIFT. Cubic CeO2 was found to serve as the lattice framework in the support of mixed oxides. Fe2O3 phase are mainly formed on the surface of CeO2 lattice in the CF involved samples, and the 'topped' Fe2O3 phase on the CeO2 crystals may facilitate the incorporation of iron atoms into CeO2 lattice. The high fraction of oxygen vacancy in catalyst Cu/CF may also facilitate the redox cycle of oxygen during catalytic reactions. The interaction of Cu oxide with CF support favourably promotes the reduction of Cu oxide and diffusion of surface oxygen species at low temperatures. During the NO + CO catalytic reactions, CeO2 serves as the storing sites of carbonate and enhances CO oxidation, Fe2O3 serves as the storing sites of nitrites and nitrates and facilitates NO,, adsorption, and impregnated copper helps to convert inactive nitrites into active intermediates for NO + CO reaction. The promoted adsorption and conversion of both carbonates and nitrite/nitrates over catalyst Cu/CF could be the reason of its excellent catalytic activity for NO + CO reaction.