The Preparation And Characterization Of Nano-carbon Supported Cobalt Based Fischer-tropsch Synthesis Catalysts

Due to the energy resource structure of abundancy in coal and deficiency in oil and gas,efficient utilization of coal and development of Fischer-Tropsch synthesis technology are vital for reducing the dependence on foreign oil and ensuring national energy security.Development of high efficient catalyst is the key to Fischer-Tropsch synthesis technology.Compared to the iron-based catalyst,cobalt catalyst possesses several advantages such as the simple preparation process,high selectivity to heavy hydrocarbons,long service time and easy to regenerate.In this paper,a series of supported cobalt catalysts were prepared by selecting inert carbon nanotubes and graphene as research object.The effect of physicochemical property and preparation conditions of nanotubes and graphene on catalyst dispersion,reducibility and catalyst performance in Fischer-Tropsch reaction were investigated in comparison with the traditional alumina support.The calcination temperature and preparation method of carbon nanotubes supported cobalt catalyst was investigated in this study.The result shows that the catalyst calcined at 350? produces the largest pores,lowest reduction temperature and highest CO conversion.Among the three preparation methods,the co-impregnation preparation method shows the best results and its CO conversion reached the highest value,heavy hydrocarbons selectivity reached the highest value.The effect of different solvents and hydrothermal temperature used in catalyst preparation on catalyst structure and catalystic performance of the graphene supported cobalt catalyst were also investigated.And the results show that the catalyst prepared with ethanol not only produces a better thermostability,a better Co3O4 dispersion,but also higher CO conversion and higher heavy hydrocarbons than deionized water prepared catalyst.The hydrothermal treatment at 200? yields the highest reducibility and the best catalytic activity.After studying different alcohol types and calcinaton temperature on the aluminum oxide supported cobalt catalyst,it is found that ethylene glycol prepared catalyst got the highest CO conversion,375? calcined catalyst got the highest CO conversion and heavy hydrocarbon selectivity.In the comparative studies of different support materials,nano-carbon supported cobalt catalyst shows obvious advantage over other catalyst support materials in product selectivity,i.e.,lower methane selectivity and higher C5+ selectivity.