Study on the steam reforming of ethanol over cobalt oxides

A high valence cobalt oxide, CoOx, was prepared from a cobalt nitrate aqueous solution through precipitation with sodium hydroxide and oxidation by hydrogen peroxide. Furthermore, pure nanocrystalline cobaltic oxide (Co3O4) particles were obtained from the CoOx by calcination at 300, 500 and 700 °C (labeled as C300, C500 and C700, respectively). All samples were characterized by X-ray diffraction (XRD), Raman spectroscopy and temperature-programmed reduction (TPR). Their catalytic activities toward steam reforming of ethanol (SRE) were tested in a fixed-bed reactor. The results showed that the phase components were transferred upon the treatment temperature, i.e., the CoOx exhibited mainly CoO(OH), C300, C500 and the C700 exhibited Co3O4. The as-prepared CoOx catalyst under low temperature possessed high activity. The best yield of hydrogen (YH2)(YH2) approached the theoretical value around 375 °C. Under H2O/EtOH molar ratio of 13 and 22,000 h−1 gas hourly space velocity (GHSV) for the as-prepared CoOx catalyst, the YH2YH2 arrived 5.72 and only minor CO (<2%) and CH4 (<0.8%) were detected.