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The Study On Meso-porous Carbon Supported Co-based Catalyst For Fischer-Tropsch Synthesis

Posted on:2018-09-21Degree:MasterType:Thesis
Country:ChinaCandidate:C H ChenFull Text:PDF
GTID:2321330518473601Subject:Industrial Catalysis
Abstract/Summary:PDF Full Text Request
With the gradual depletion of oil resources,whether it is the raw material of gasoline,diesel and other liquid fuels can be sustained and stable supplied has become a major consumer market worries.Coal,natural gas and biomass production of liquid fuel technology has attracted more and more attention,and Fischer-Tropsch(F-T)synthesis is one of the important ways to achieve this transformation.Cobalt(Co)-based catalysts with higher CO hydrogenation activity and F-T reaction chain growth ability,with higher production capacity of high conversion rate,applicable to the higher ratio of hydrogen to carbon reaction system,reaction process is more stable and is not easy to carbon deposition and poisoning,products of oxygen containing compounds,not sensitive to water gas shift reaction.Therefore,Co-based catalyst is regarded as the first choice for the F-T reaction at low temperature long chain hydrocarbon,and has a good application prospect.In this paper,We focus on the influence of the preparation method of mesoporous carbon carrier and the structural properties of mesoporous carbon carriers to F-T synthesis reaction activity and product selectivity of Co-based catalysts.The effect of modification on the reactivity and theselectivity of the catalyst for the SBA-15 supported Co-based catalyst were discussed.The selectivity of the different catalysts for gasoline(C5-C10)and diesel(C10-C20)products is quite different.The following results were obtained by X-ray diffraction(XRD),N2 physical adsorption-desorption,TPR and scanning electron microscopy(SEM).(1)A series of ordered mesoporous carbon with tunable pore size,surface area were prepared using sucrose as carbon source,SBA-15 as template at different temperatures.As demonstrated by N2 adsorption tests,the pore size increases from 3.42 to 5.14 nm,specific surface area increases from 410.50 to 1141.00m2·g-1.Catalyst performance test shows that the F-T synthesis catalytic activity and product selectivity depended strongly both on the pore size and surface area of the catalysts.The catalyst with a pore size of 5.14 nm and specific surface area of 1003.68m2·g-1 showed the best F-T synthesis activity and the highest selectivity to C5+,including the selectivity of C10-C20 reached 56.19%.(2)The effect of carbon-modified SBA-15 carrier on the activity of Co-based catalyst and the selectivity of the product was investigated by filling the SBA-15 with different mass ratios of carbon.The addition of sucrose at different mass ratios resulted in a decrease in the reactivity of the Co-based catalyst,but at the same time the distribution of the F-T reaction product of the catalyst shifted significantly.In the catalyst Co/SBA-15 C,the CO conversion of the catalyst and the C5+ selectivity of thecatalyst showed a tendency to decrease first and then decrease again with the increase of sucrose content.Co/SBA-15C3 has the highest C5+selectivity,where C5-C10 selectivity is as high as 55.85%.(3)Breath figure method was used to prepare porous films from polystyrene(PS,PG-22).The morphology of the porous film was observed by scanning electron microscopy(SEM).The results show that the optimal parameters to prepare ordered porous polystyrene films are 25mg/mL(polymer concentration),0.8 mL(the dosage of PS solution)and85% RH(environmental humidity)under 25 ? C static atmosphere and toluene as solvent.The thickness of ordered porous films can be increased by multi-coating.On the basis of this,the SBA-15 was modified by PS ordered porous films.It was found that the catalytic activity of the catalyst was lower due to the clogging of the catalyst and the decrease of the reduction degree,The CO and CH4 selectivity of the catalyst increased,C5+ selectivity decreased.
Keywords/Search Tags:ordered mesoporous carbon, Fischer-Tropsch synthesis, SBA-15, carbon modification, breathing figure method
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