Fischer-Tropsch Synthesis Performance On Titanium Silica Molecular Sieve Supported Co-based Catalyst

With the development of world economy,the amount of crude oil consumption increased.Dependent on the rich coal resource in our country,the coal-to-syngas（hydrogen and carbon monoxide）technology and Fischer-Tropsch synthesis（FTS）process which convert syngas for production of ultraclean fuel oil is of great importance for slowing down the tense situation of petroleum,solving environmental problems and optimizing energy consumption structure.The key step of Fischer-Tropsch synthesis lies in the development of highly efficient catalysts.Titanium silica molecular sieve（TS）was used as support to prepare cobalt based catalysts.The acid treatment,base treatment and acid-base co-treatment of TS increased the FTS performance of Co/TS catalyst due to the more mesoporous structures.The increase of TS pore size increased dispersion of cobalt particles,improved diffusion rate of reactant and resultant and then enhanced catalytic activity.Further,it was found that base treatment increased crystallinity degree of TS by removing amorphous silicon and then improved the stability of Co/TS,while acid treatment has the opposite effect.In order to better understand the support pore size effect on Co-based catalysts,mixed-support was prepared by mixing TS and TiO₂.It was observed that catalytic performance has been improved by using mixed-support compared to the single supported catalysts,and CO conversion reached maximum in Co/Mixed-1.It was revealed that the superior catalytic performance could be attributed to the enhanced diffusion rate,high cobalt dispersion and large number of active sites,which result from an optimum ratio of TS/TiO₂.The effect of preparation methods on co-based catalysts was further investigated.Co-based catalysts were prepared by dielectric-barrier discharge DBD plasma in inert gases and hydrogen,the effect of discharge atmosphere on FTS catalytic activity was studied.It was found that DBD plasma in inert gases could replace the calcination process and reduce cobalt precursor at a lower temperature and in a shorter time.FTS catalytic activity is related to the inert gas discharge ability.The stronger the discharge ability,the higher the catalytic activity is.So the catalyst pretreated by He plasma has the highest CO conversion due to highest discharge ability of He.Meanwhile,H₂-DBD plasma can be an alternative way to replace the traditional calcination and reduction process,achieving equivalent catalytic FTS performance.