Study On Performance Of Fischer-Tropsch Synthesis On Carbon Nanotube Supported Co-based Catalyst

Fischer-Tropsch synthesis （FTS） attracts growing interest due to the oil crisis.Co-based catalyst appears to provide the best compromise between performance andcost for the synthesis of hydrocarbon from syngas and is considered one of the mostpromising catalytic systems. Conventionally, cobalt precursors are dispersed onporous carriers such as SiO₂and Al₂O₃. The drawback of these support materials isthe formation of hard-reducible compounds due to the strong interaction betweencobalt and support. During conventional catalyst preparation, calcination is used totreat the catalyst, which leads to the sintering and aggregation of cobalt oxides. Inorder to prevent these phenomena, SiO₂and CNTs were used to support Co-basedcatalyst. After impregnation and drying, calcination or dielectric barrier discharge（DBD） plasma were introduced to treat the catalysts. To study the effect of CNTs assupport material and DBD plasma as catalyst treatment method on the FTSperformance of catalysts, the catalysts were characterized by N2-physisorption,temperature programed reduction （TPR）, transmission electron microscope （TEM）and X-ray diffraction （XRD）. The FTS performance was evaluated in a fixed bedreactor. The results show that using CNTs as support and DBD plasma treatment allincrease the cobalt oxide dispersion, reduction degree and FTS performance.On Co/CNT catalyst, a fraction of the cobalt particles was distributed inside thetubes and the rest on the outer side. Using CNTs as the support material leads toshorter induction period and enhanced FTS activity due to the smaller particlediameter, narrower particle size distribution and lower reduction temperaturecompared with Co/SiO₂catalyst. The temperature of FTS on Co/SiO₂catalystfluctuated greatly in the induction period while it was stable on Co/CNT catalyst.Compared with conventional calcination method, the DBD plasma treatedCo-based catalysts showed bigger specific surface area, smaller cobalt particles,higher cobalt dispersion and shorter induction period for FTS reaction. DBD plasmatreated Co/SiO₂catalyst has a better CO conversion and C5+selectivity. Also, the FTSreaction was stable compared with that on calcined Co/SiO₂catalyst.