Investigation of Co-ZSM-5 catalyst in Fischer-Tropsch Synthesis for fuel production

Due to high activity of cobalt metal in syngas conversion to higher hydrocarbons, supported cobalt catalysts have been widely used for Fischer-Tropsch synthesis (FTS) reaction. Cobalt catalyst is very active to produce long chain normal paraffin and also it shows high resistance to deactivation[1,2]. The present of strong acid sites in Co/H-ZSM-5 influence mainly the selectivity to the C5-C12 hydrocarbons. The application of CoZSM-5 having in its structure weak acid sites exhibited greater selectivity to C5-C8 hydrocarbons [3,4]. Co-ZSM-5 catalyst was prepared by a wet impregnation method. The Co loading was 15 wt.% on the catalyst. After evaporating to eliminate water, the samples were dried at 120 oC for 20 h and calcined at 400 oC for 3 h. The catalyst was pressed into pellet, crushed and sieved 16-30 mesh . The catalysts were characterized using XRD, H2-TPR,SEMand BET techniques.The effect of ZSM-5 on catalytic performance of Co catalyst was studied in a fixed bed reactor at the following conditions: 220°C, 25 atm, H2/CO of 2 and gas space velocities of 1.8 nl/(g cat.h). The catalyst was activated in situ with hydrogen at 400 °C for 16 h. CO conversion and product distribution was calculated by results of gas chromatography. Selectivities of light hydrocarbon products increased with adding of ZSM-5 zeolite into the catalyst, whereas selectivity of heavy hydrocarbons decreased.

Keywords:

Fischer-Tropsch Synthesis , Co-ZSM-5 catalyst , product distribution