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Cu/SiO_2 catalysts prepared by different methods have been investigated focusing on the influence of Cu~+on the catalytic performance.The composition,structure and copper valence state were characterized by means of BET,XRD,XPS,FTIR,N_2O-titration.It was found that the Cu/SiO_2 prepared by ammoniaevaporation(AE) method had much higher TOF value than that prepared by wetness-impregnation(WI)with the same THF selectivity.The higher TOF value was attributed to the coexistence of Cu~+ and Cu~0species in the activated AE-Cu/SiO_2.while only Cu° species existing in the activated Wl-Cu/SiO_2.Researches suggest that Cu~+ can adsorb and polarize the C=0 bond of DMM.It is concluded that Cu°could be the main active site and the synergistic effect between Cu~0 and Cu~+ could contribute to hydrogenation of DMM to THF.
Cu / SiO 2 catalysts prepared by different methods have been investigated focusing on the influence of Cu ~ + on the catalytic performance. The composition, structure and copper valence state were characterized by means of BET, XRD, XPS, FTIR, N_2O-titration.It was found that the Cu / SiO 2 prepared by ammoniaevaporation (AE) method had much higher TOF value than that prepared by wetness-impregnation (WI) with the same THF selectivity. the higher TOF value was attributed to the coexistence of Cu ~ + and Cu ~ 0species in the activated AE-Cu / SiO 2. While only Cu ° species existing in the activated Wl-Cu / SiO 2. Researches suggest that Cu ~ + can adsorb and polarize the C = 0 bond of DMM. It is said that Cu ° could be the main active site and the synergistic effect between Cu ~ 0 and Cu ~ + could contribute to hydrogenation of DMM to THF.