Ethanol Steam Reforming on Co/CeO2: The Effect of ZnO Promoter
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A series of ZnO promoted Co/CeO2 catalysts were synthesized and characterized using XRD, TEM, H2-TPR, CO chemisorption, O2-TPO, IR-Py, and CO2-TPD. The effects of ZnO on the catalytic performances of Co/CeO2 were studied in ethanol steam reforming. It was found that the addition of ZnO facilitated the oxidation of Co0 via enhanced oxygen mobility of the CeO2 support which decreased the activity of Co/CeO2 in C–C bond cleavage of ethanol. 3 wt% ZnO promoted Co/CeO2 exhibited minimum CO and CH4 selectivity and maximum CO2 selectivity. This resulted from the combined effects of the following factors with increasing ZnO loading: (1) enhanced oxygen mobility of CeO2 facilitated the oxidation of CH x and CO to form CO2; (2) increased ZnO coverage on CeO2 surface reduced the interaction between CH x /CO and Co/CeO2; and (3) suppressed CO adsorption on Co0 reduced CO oxidation rate to form CO2. In addition, the addition of ZnO also modified the surface acidity and basicity of CeO2, which consequently affected the C2–C4 product distributions.
KeywordsEthanol steam reforming Hydrogen Cobalt CeO2 ZnO promoter
We acknowledge the financial support from the US Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, the WSU Franceschi Microscopy Center and Dr. Knoblauch for use of the TEM, and the WSU GeoAnalytical Lab and Dr. Rowe for use of the XRD. S.D. thanks Feng Gao and Yilin Wang for many helpful discussions in the early stage of this work.
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