Surface Structure and Catalytic Properties of Cu/SiO2 Catalysts Prepared by Different Methods

摘要

The silica supported copper catalysts were prepared via impregnation (IM), sol-gel (SG) and deposition precipitation (DP) methods. The catalysts were characterized by XRD, H2-TPR, NH3-TPD, H2-N2O titration, XPS, BET and EPR techniques. The results indicated that two copper species, Cu~(2+) and Cu~0 exist on the surface of SG catalyst; however, only Cu~0 species could be found on the surface of reduced IM and DP catalysts, and the dispersion of Cu~0 on IM catalyst was better than that on DP catalyst. According to the reaction results, Cu~0 should be the active sites for dehydrogenation of cyclohexanol. Cu~(2+) species on the surface of SG catalyst might be responsible for the dehydration of cyclohexanol. The residual Na was found on the surface of DP catalyst, which made the acidity decreasing, and the Cu crystallite growing up easily.