Auto-Reduction Behavior of Cobalt on Graphitic Carbon Nitride Coated Alumina Supports for Fischer-Tropsch Synthesis

Abstract

Graphitic carbon nitride (g-C3N4)-coated alumina (CN-Al) is investigated as a support material for a cobalt-based Fischer-Tropsch synthesis (FTS) catalyst. The g-C3N4 blocks the interaction between cobalt and alumina to hinder the formation of irreducible cobalt oxide species, and improves the dispersion of metallic cobalt species on the CN-Al support. Furthermore, the coated g-C3N4 is decomposed during the pre-annealing process even under inert conditions to evolve reductive carbon monoxide gas that directly reduces the cobalt oxide species to metallic cobalt. Hence, the catalyst can be activated without typical hydrogen pretreatment. Moreover, reduction promotion by expensive noble metals such as Pt is not needed either. Because of the improved dispersion and reducibility of the cobalt species on the CN-Al support, the catalytic FTS activity of Co/CN-Al is higher compared with the conventional Co/Al2O3 catalyst.