Effects Of Noble Metal Promoter And Tungsten Promoter On Fe@C Catalyst For Fischer-tropsch Synthesis

With the depletion of crude oil resources,every country is trying to find substitute for crude oil.For converting syngas into a various of oil products and high value-added chemicals,Fischer-Tropsch synthesis(FTS)has received increasing attention.Based on the energy structure of our country with more coal and less oil,converting coal to liquid fuels with FTS as the core is in line with the strategic demand of national sustainable development.In previous studies,our research developed a kind of special melting method to prepare FTS iron-based catalyst.Compared with the traditional supported iron catalyst and precipitated iron catalyst,the Fe@C catalyst prepared by melting method has advantages of highly dispersed active phase,rich pore structure and special encapsulation structure,so it has better catalytic performance.The catalytic performance of Fe-based catalysts can usually be improved by adding promoters.In this thesis,we systematically investigated the effects of noble promoters and W promoter on the performance of catalyst.We prepared 35Fe@C+0.2M(M=Ru,Rh,Pt,Ag)and 35Fex W@C(x=2,6,10)catalysts by one-step melting method.The effect of these promoters on the performance of 35Fe@C are discussed.The results are as follows:(1)Small amount of noble promoter have little effect on the physical properties of 35Fe@C catalyst.The addition of noble promoter is beneficial to the reduction of catalyst while the carburization process was delayed by which.Carbonization degree of35Fe@C+0.2Ag catalyst might be higher than 35Fe@C,which could be responsible for the higher FTY value.Pt promoter could improve the C₅₊selectivity and suppress light hydrocarbons selectivity simultaneously.The catalytic activity decreased with the addition of Ru,Rh and Pt promoter,which could be attributed to the decreased of dispersion and the supression of carburization of Fe species.(2)As a structural promoter,W could improve the dispersion of 35Fe@C.However,the interaction between W and Fe inhibited the reduction and carburization of35Fex W@C significantly.Compared with the 35@Fe catalyst,W promoted catalysts exhibited lower CO₂ selectivity and higher C₅₊selectivity.