The effect of accessible oxygen over Co3O4–CeO2 catalysts on the steam reforming of ethanol

Abstract

The effect of accessible oxygen on the steam reforming of ethanol (SRE) over Co3O4–CeO2 catalysts was investigated. Both equal molar ratio of Co3O4–CeO2 catalysts were prepared by hydrothermal co-precipitation (H), and hydrothermal ultrasonic-assisted co-precipitation (UH) methods and characterized through X-ray diffraction (XRD), in situ temperature programmed reduction/temperature programmed oxidation (TPR/TPO), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and elemental analysis (EA) techniques at various stages of the catalyst. The results indicated that the incorporation of cobalt ion into the ceria lattice could increase the dispersion of catalyst, oxygen vacancies and promote the oxygen-storing and releasing capability of ceria, especially over the catalyst prepared by ultrasonic-assisted method. The accessible oxygen played an important role on the SRE reaction and resistant to carbon deposition. The Co–Ce (UH) catalyst was more active and selective in the SRE reaction, where ethanol was fully converted and hydrogen selectivity (SH2) was about 70% at 400 °C under H2O/EtOH molar ratio of 13.0 and gas hourly space velocity (GHSV) of 22,000 h−1. The high oxygen storage capacity (OSC) and high accessible oxygen for the Co–Ce (UH) catalyst allowed oxidation/gasification of deposited carbon as soon as it formed, and less coke was detected.