Enhanced Fischer-Tropsch synthesis performance on MOFs-derived Fe-based catalysts constrained by SiO2

Fischer-Tropsch synthesis (FTS) is an essential technology to produce clean fuel, and catalyst will affect syngas conversion efficiency and product distribution. For traditional oxides-supported catalysts, the mutual constraint between active metal loading and dispersion at high metal loading is hard to overcome, which will hinder the synthesis of high-performance FTS catalysts. Herein, we report an efficient method for synthesizing iron-based catalysts with not only high loading but also high dispersion. By using metal-organic frameworks Fe-MIL-88B as the precursor, we synthesized a series of Fe@C@SiO2 catalysts by tuning the amount of tetraethyl orthosilicate (TEOS) through a one-step method; TEOS was in situ introduced and followed by high-temperature carbonization. The prepared catalyst possesses a Fe@C core-shell structure with carbon layer encapsulation. Meanwhile, the SiO2 in the catalyst can effectively confine iron particles and avoid the agglomeration of iron species during high-temperature carbonization. Among these catalysts, the Fe@C@SiO2-0.005 showed the greatest FTS performance because high iron dispersion was achieved at high iron loading. Further increase SiO2 content enhanced the confinement effect of SiO2 but generated inert Fe2SiO4 species, which decreased the adsorption and activation of reactants and FTS activity.