Study on the steam reforming of ethanol over cobalt oxides

Abstract

A high valence cobalt oxide, CoO x , was prepared from a cobalt nitrate aqueous solution through precipitation with sodium hydroxide and oxidation by hydrogen peroxide. Furthermore, pure nanocrystalline cobaltic oxide (Co 3O 4) particles were obtained from the CoO x 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 CoO x exhibited mainly CoO(OH), C300, C500 and the C700 exhibited Co 3O 4. The as-prepared CoO x catalyst under low temperature possessed high activity. The best yield of hydrogen ( Y H 2 ) approached the theoretical value around 375 °C. Under H 2O/EtOH molar ratio of 13 and 22,000 h −1 gas hourly space velocity (GHSV) for the as-prepared CoO x catalyst, the Y H 2 arrived 5.72 and only minor CO (<2%) and CH 4 (<0.8%) were detected.