Cu-Cr, Cu-Mn, and Cu-Fe Spinel-Oxide-Type Catalysts for Reforming of Oxygenated Hydrocarbons

Effective hydrogen production is achieved via steam reforming of the oxygenated hydrocarbons, including methanol and dimethyl ether, over Cu-based spinel-oxide catalysts. CuFe2O4, CuMn2O4, and CuCr2O4 were well-crystallized in spinel structures and were provided with low specific surface areas below 2 m(2) g(-1). Upon reduction, the spinels possessed Cu+-rich surfaces when compared with a commercial Cu/ZnO/Al2O3, which resulted in better catalytic performance in methanol steam reforming (MSR). The composite catalysts of the Cu spinel and gamma-Al2O3 were promising for dimethyl ether steam reforming (DMESR) in terms of activity, selectivity, and stability. The descending order of the DMESR activity over the composite catalysts was as follows: CuFe2O4-gamma-Al2O3 > CuMn2O4-gamma-Al2O3 > CuCr2O4-gamma-Al2O3, which was in line with the MSR activity over Cu-spinel catalysts. This revealed that the MSR activity strongly contributed to the high DMESR activity using the composite Cu-spinel catalysts and gamma-Al2O3. The theoretical calculations demonstrated that the observed MSR reactivity trend follows the reactivity of the MSR rate-limiting step of methoxy dehydrogenation. The required active sites are shown to be both Cu and metal oxide in the facilitation of methoxy dehydrogenation.