A Comparison of Oxygen-vacancy Effect on Activity Behaviors of Carbon Dioxide and Steam Reforming of Methane over Supported Nickel Catalysts

Partial oxidative steaming reforming of methanol (POSRM) to produce hydrogen selectively for polymer electrolyte membrane fuel cell (PEMFC) powering vehicles was studied over Cu–ZnO/samaria-doped ceria (SDC) catalyst. Compared with Cu–ZnO/α-Al₂O₃ and Cu–ZnO/γ-Al₂O₃ catalysts, the Cu–ZnO/SDC catalyst exhibited higher activity for CH₃OH conversion and higher selectivity for H₂ production in the POSRM reaction. The higher catalytic performance of Cu–ZnO/SDC appears attributable to the support effect of SDC. Effects of reaction temperature, O₂/CH₃OH and H₂O/CH₃OH molar ratios on the catalytic performance of Cu–ZnO/SDC were investigated. It has been found that the partial-oxidation nature of the POSRM reaction is increased when O₂/CH₃OH ratio is increased, and the combustion of methanol and H₂ would occur insignificantly in the POSRM over the Cu–ZnO/SDC catalyst. A higher concentration of steam is beneficial to suppress CO formation over the Cu–ZnO/SDC catalyst. Under the experimental conditions of the present work, the O₂/CH₃OH and H₂O/CH₃OH molar ratios should be about 0.02 and 1.0–2.0, respectively, in order for Cu–ZnO/SDC to achieve an optimum catalytic performance.