Adjusting Hydrocarbon Distribution on the Stabilized Al-Modified Mesoporous Co₃O₄-Fe₂O₃ Bimetal Oxides for CO Hydrogenation

A higher selectivity to C₂−C₄ hydrocarbons and clean fuels without significant deactivation during CO hydrogenation by a typical Fischer-Tropsch synthesis (FTS) was observed on the ordered mesoporous 5wt %Al-modified Co₃O₄-Fe₂O₃ bimetal oxides (m-CoFe) at a Co/Fe molar ratio of ∼1, which was prepared by a hard templating and co-infiltration method. The active sites were related with the partially oxidized Co nanoparticles as well as iron carbides. The structurally stable and strongly interacted ordered Co₃O₄-Fe₂O₃ mesoporous structures were preferentially transformed to more brittle iron carbides with a simultaneous reduction of Co₃O₄ to metallic Co under a reductive FTS reaction condition. The m-CoFe(1) itself without using any solid acid component revealed a higher C₂−C₄ selectivity of 21.1 % and C₅₊ selectivity of 67.9 % at CO conversion of 88.5 % with the corresponding rate of 2.77 mmol/(g_cat⋅s) by enhancing its structural stability due to the partial formations of thermally stable spinel-type CoFe₂O₄. The enhanced structural stability of the m-CoFe(1) was attributed to the preferential formations of the strongly interacted and partially oxidized Co nanoparticles with the formation of active iron carbides as well.