Study On Preparation And Process Of Fischer-tropsch Synthesis Catalyst

Coal-to-liquid technology(CTL)is one of the known processes for the production of liquid synthetic hydrocarbons from the syngas(CO and H2).This technology includes three steps:syngas production from coal gasification,syngas converts to hydrocarbon products via the catalytic Fischer-Tropsch Synthesis,and upgrading of hydrocarbons process(hydrocracking and hydroisomerization).The composition of Fischer-Tropsch synthesis products depends on the catalyst features and reaction conditions.It is known that cobalt-based catalysts are the most efficient for the production of linear hydrocarbons with the C5+ chain length at low temperature and pressure of the synthesis,with low selectivity for the formation of methane,and low activity in WGSR.Co-B-C/?-Al2O3 catalyst was prepared with cobalt as active component and different sources of alumina as support,adding B and C as promoters via three-step equal volume impregnation method.The effects of additives, supports and activation conditions on the F-T synthesis were investigated.The results showed that the Co-3B-C/?-Al2O3 catalyst prepared by self-made support had good catalytic activity and product selectivity.In a continuous flow fixed bed reactor,the effects of reaction conditions on Co-3B-C/?-Al2O3 were tested in temperature range of 230-242.5 ?,pressure range of 1.5-3 MPa,GHSV range of 1000-2500 h'1,H2/CO range of 1.5-3 molar ratios,reduction time range of 12-48 h and oxidation-reduction times range of 0-3 times.The results showed that best selectivity to CH4 was 7.8%and C5+ was 82.1%,with 40.6%CO conversion under the condition of 235 0C,2.5 MPa,H2/CO=2,GHSV=1500h-1,the reduction time was 24 h and oxidation-reduction was zero.The stability of cobalt-based catalysts for F-T synthesis was investigated.In the long-term experiments with continuous operation of 1200 hours,the conversion of CO can always be maintained around 30%which was always used in industry,and the C5+ selectivity was above 68.9%,all of these indicated the catalyst that we prepared had high activity and stability,it was an ideal catalyst for F-T synthesis.