Superior catalytic performance of non-stoichiometric solid solution Ce1-xCuxO2-δ supported copper catalysts used for CO preferential oxidation

A series of Ce-1 - xCuxO2 (-) (delta) non-stoichiometric solid solutions and their supported copper catalysts CuO/Ce-1 - xCuxO2 (-) (delta) (X = 0, 0.005, 0.022, 0.043) were prepared by co-precipitation and deposition-precipitation, respectively. The CuO/Ce-1 - xCuxO2 (-) (delta) catalysts show high performance for CO preferential oxidation (CO PROX). Multiple techniques of N-2 sorption (BET), XRD, Laser Raman spectroscopy (LRS), HRTEM, H-2-TPR, O2- TPO, N2O chemisorption and in-situ DRIFTS were used for catalyst characterization. The results of XRD, LRS and H-2-TPR conformably indicate that a small amount of Cu2+ ions can be incorporated into the lattice of CeO2, forming non-stoichiometric solid solutions Ce-1 - xCuxO2 (-) (delta), which shows much better reducibility than pure CeO2. The supported Ce-1 - xCuxO2 (-) (delta) catalysts exhibit remarkably enhanced activity for CO PROX as compared with CuO/CeO2, especially the catalyst CuO/Ce0.978Cu0.022O2 (-) (delta) containing 15% Cu, which displays the best CO PROX performance, showing not only the lowest temperature (115 degrees C) for CO total conversion, but also the 100% selectivity of O-2 to CO2 at this temperature. Several aspects including the presence of more oxygen vacancies, the improved reducibility, and stronger capability for CO chemisorption of this catalyst account well for its superior performance for CO PROX Based upon the in-situ DRIFTS study, it is revealed that Cu+ is the main active site for CO oxidation, while Cu-0 is more active for H-2 activation and oxidation. (C) 2014 Elsevier B.V. All rights reserved.