Efficient production of hydrogen over supported cobalt catalysts from ethanol steam reforming

The reaction between ethanol and water was studied in the temperature range 573-723 K at atmospheric pressure over supported cobalt catalysts. Cobalt-loaded catalysts (1%) were prepared by impregnation Of Co-2(CO)(8) on MgO, gamma-Al2O3, SiO2, TiO2, V2O5, ZnO, La2O3, CeO2, and Sm2O3. Ethanol steam reforming occurred to a large degree over ZnO-, La2O3-, Sm2O3-, and CeO2-supported catalysts; CO-free hydrogen was produced. Samples were characterized after catalytic tests by high-resolution transmission electron microscopy, electron diffraction, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed hydrogen reaction. Depending on the support, different cobalt-based phases were identified: metallic cobalt particles, Co2C, CoO, and La2CoO4. The extent and nature of carbon deposition depended on the sample and on the reaction temperature. ZnO-supported samples showed the best catalytic performances. Under 100% ethanol conversion, selectivity up to 73.8% to H-2 and 24.2% to CO2 was obtained. (C) 2002 Elsevier Science (USA).