Investigation of Surface Structures of Supported ZnO/SiO2 and ZnO-SiO2 Sol-gel Catalysts

ZnO/SiO2 and ZnO-SiO2 catalysts were prepared by the impregnation and sol-gel method, respectively. The characterization of the catalysts by XPS and FTIR indicated that much free zinc oxide and unreacted Si-OH existed on the surface of ZnO/SiO2 sample. As for ZnO-SiO2 sol-gel catalyst, the corresponding phenomena were not observed. The prepared samples were also used as the catalysts for decomposition of 2-butanol. A high selectivity for dehydrogenation was observed over the supported catalyst. However, a high selectivity for dehydration was shown over the ZnO-SiO2 sol-gel catalyst. The opposite selectivity for dehydration or dehydrogenation observed over the two kinds of catalysts may be just because of the different surface structures of the catalysts.