Mn或K修饰ε-Fe2C催化剂的制备及其费托合成性能研究OA

Iron-based catalysts play a crucial role in Fischer-Tropsch Synthesis(FTS).However,their complex phase structures and high by-product selectivities limit further development.It is urgent to establish single-phase iron catalysts,explore the reaction processes and increase target product selectivities with promoters.Highly stable ε-Fe2C catalysts were successfully prepared by pyrolysis of Prussian Blue Analogues,and the effects of Mn and K promoters on the catalyst structures and catalytic performances were investigated.The results show that under reaction conditions of 270 ℃,3 MPa,n(H2):n(CO)=2:1,and gas hourly space velocity(GHSV)of 30000 mL/(g·h),with the Mn-modified ε-Fe2C catalyst,CO2 selectivity decreases to 7.5%,and with the K-modified ε-Fe2C catalyst,C5+hydrocarbon selectivity reaches 71.5%after 25 h reaction.The catalysts modified by the two promoters maintain ε-Fe2C structure before and after the reaction,and their activities and product selectivities remain stable during 80 h reaction.The Mn-modified ε-Fe2C catalyst exhibits better catalytic performance due to low by-product selectivity.By characterization methods such as XRD,TEM and XPS,the microstructural changes and their effects on FTS catalytic performances of the catalysts were revealed.It is found that the size effect produced by promoters results in a decrease in CO conversion rate with catalysts.Mn and K,as electronic promoters,provide electrons to the catalysts,ensuring the stability of the surface structures and regulating product distributions.The introduction of promoters into ε-Fe2C catalysts can effectively regulate catalytic activities and product distributions,providing a novel strategy for the development of FTS catalysts with high product selectivities.