Catalytic Roles of Co0 and Co2+ during Steam Reforming of Ethanol on Co/MgO Catalysts

The catalytic roles of Co-0 and Co2+ during steam reforming of ethanol Were investigated over Co/MgO catalysts. Catalysts with different Co-0/(Co-0 + Co2+) fraction were prepared through calcination and/or reduction at different temperatures, and the Co-0 fraction was quantified by temperature programmed reduction (TPR) and in situ X-ray photoelectron spectroscopy (XPS). Higher temperature calcination of Co/MgO allowed us to prepare catalysts with more nonreducible Co2+ incorporated in the MgO lattice, while lower calcination tempratures allowed for the preparation of catalysts with higher Co-0/(Co-0 + Co2+) fractions. The catalytic tests on Co-0, nonreducible Co2+, and reducible Co2+ indicated that Co-0 is much more active than either reducible or nonreducible Co2+ for C-C cleavage and water gas shift reaction. In addition, catalysts with a higher Co-0 surface fraction exhibited a lower selectivity to CH4.