摘要
A series of oxideized CO-K-Mo/γ-Al2O3 catalyst samples,prepared by impregnating oxidized K-Mo/γ-Al2O3 samples with an aqueous solution of calculated Co(NO3)2 and then calcining in air at temperatures of 350℃，500℃65℃ and 800℃ respectively,were sulfided and then investigated for the activity in the synthesis of mixed alcohols from CO hydrogenation under conditions of p=5.0MPa,T=350℃ and GHSV=4800h^-1 .The results demonstrate that the addition of cobalt promoter is favorable to the formation of higher alcohols and the opimum calcination temperatures after impregnating with Co^2+ are about 500-650℃.The structure of Co and Mo species on the oxidized and sulfided samples was determined by X-ray diffraction(XRD),laser Raman spectrum (LRS) and extended X-ray absorption fine structure (EXAFS).For oxidized sample calcined at 350℃ ,cobalt exists as Co3O4 specties and covers the surface of K-Mo-O species,the structure of K-Mo-O species is the same as that in K-Mo/Al2O3 sample.The interaction between cobalt and K-Mo-O species is relatively weak.After sulfidation.Cobalt exists as sulfide crystallites with an octahedral coordinated structure,and molybdenum as MoS2 crystallites.For oxidized samples calcined at 500-650℃,Co component interacts with the K-Mo-O species and destroys the long-range order of the K-Mo-O spectes gradually,After sulfidation.Co tends to exist as a sulfide with tetrahedral coordinated structure and Mo still as MoS2 crystallites.For oxidized sample calcined at 800℃,Co component exists mainly as CoAl2O4 species,most of which cannot be sultided during sulfidation.
