Promotional effect of Partial substitution of Zn by Ce in CuZnAlO catalysts used for hydrogen production via steam reforming of dimethyl ether

A series of CuZnAlCeO catalysts with Zn partially substituted by Ce were prepared by co-precipitation, and employed for hydrogen production via dimethyl ether steam reforming (DME SR). The catalytic activity of these catalysts largely depends on CeO2 content. The catalyst containing 10 wt% CeO2 exhibits the best catalytic performance. The techniques of X-ray diffraction (XRD), N2O chemisorption, X-ray absorption fine structure (XAFS, including XANES and EXAFS), temperature-programmed reduction (H-2-TPR) and CO desorption (CO-TPD) were used for catalyst characterization. The results of XRD, H-2-TPR and N2O chemisorption conformably indicate that partial substitution of Zn by Ce can remarkably improve the dispersion of Cu species. The presence of Ce could not only inhibit the sintering of Cu species, but also improve the reducibility of copper oxides. The CO-TPD results clearly indicate that the two catalysts with 5 and 10 wt% CeO2 possess higher CO-chemisorption capability than others, which is consistent with the results of Cu dispersion. The linear fitting results of XANES spectra reveal that these two catalysts also contain higher amount of Cu+ species, which determines their better catalytic performance for DME SR. (C) 2013 Elsevier B.V. All rights reserved.