Selective hydrogen production from methanol oxidative steam reforming over Zn–Cr catalysts with or without Cu loading

Production of H2H2 from methanol oxidative steam reforming (OSRM) over Zn–Cr, high or low Cu-loading Zn–Cr–Cu catalysts was studied. The catalysts were prepared by urea–nitrate combustion approach and characterized by BET, X-ray diffraction (XRD), and temperature-programmed reduction (TPR). The influence of reaction temperature and catalyst formulation on activity, selectivity and stability were investigated. Distinct differences between the processes were observed with respect to catalyst behavior. The ZnCr catalyst without Cu has the highest stability. Zn–Cr–Cu oxide solid solution is formed by adding small amount of Cu to the ZnCr catalyst, and significantly improves the activity and suppresses CO formation. The quick deactivation of the high Cu-loading catalyst is due to Cu sintering. CO is produced via methanol decomposition on ZnCr or ZnCrCu with low Cu-content, and it may be from two pathways of methanol decomposition and reverse water gas shift on the high Cu-contained catalysts. Low Cu-containing catalysts, especially ZnCrCu2.5ZnCrCu2.5, exhibit the best performance of complete methanol conversion, less than 1% CO at the production gas and excellent stability at middle temperature of 350 °C in OSRM, and display great potential in fuel cell applications.