Study On Fischer-tropsch Performance Of Zirconium Modified Cobalt-basesd Catalyst

Currently, under the situation of shortage of oil resources and environmentalpollution becoming more serious, the synthesis of liquid fuel based onFischer-Tropsch (F-T) synthesis through the coal, natural gas and biomass is of greatimportance in energy and environment protection. The development of catalysts is thekey of F-T synthesis techology. Cobalt-based catalyst is one of most promisingcatalysts due to its excellent performance for F-T synthesis reaction.In this paper, SiO2supported cobalt-based catalysts were prepared by incipientwetness impregnation and characterized by N2-physisorption, H2-temperatureprogramed reduction (H2-TPR), H2-temperature-programmed desorption (H2-TPD),X-ray diffraction (XRD), scanning electron microscope (SEM) and transmissionelectron microscope (TEM). The F-T synthesis performance of catalyst was evaluatedin a fixed bed reactor. The influences of the pore size of supports, promoters like ceria,lanthanum and zirconium on the F-T performance of silica supported cobalt catalystswere investigated. The resulted show that the Co/Zr/SiO2B catalyst exhibited highercobalt dispersion and reducibility, which contributed to an enhanced F-T activity andhydrocarbon chain growth ability.The influences of zirconium loading, reaction temperature, reaction pressure,space velocity and H2/CO ratio on the catalytic activity and product selectivity on theCo/Zr/SiO2catalyst were studied. The suitable conditions are determined as follows:zirconium loading as5wt%, reaction temperature as230oC, pressure as2MPa,GHSV as3600h-1and n(H2)/n(CO) as2.Compared with conventional calcination method, DBD plasma treated Co/SiO2catalyst resulted smaller cobalt particles, better cobalt dispersion and higher F-Tactivity. However, cobalt reducibility was hindered to some extent for Co/SiO2catalyst prepared by DBD plasma due to the stronger interaction between Co andsupport. The DBD plasma treatment for zirconium modified SiO2support andCo/Zr/SiO2catalyst can significantly weaken the interaction between Co and supportand further increase cobalt dispersion. The catalyst prepared by this two-step DBDplasma showed an excellent F-T synthesis performance.