Insights into the mechanism of carbon chain growth on zeolite-based Fischer–Tropsch Co/Y catalysts

Abstract

In a zeolite-based Fischer–Tropsch bifunctional catalyst, zeolites, as the support of the active metal, can interact with the metal cluster to affect the electronic properties and structural effect of the catalyst, thus affecting the Fischer–Tropsch synthesis reaction. In this work, the Fischer–Tropsch synthesis process using a Co catalyst supported by Y-zeolite was simulated by the DFT method from the microscopic point of view. The reaction network was designed to investigate the reaction mechanism in terms of four parts consisting of H-assisted CO dissociation, C₁ hydrogenation, CH_x–CH_x coupling, and C₂–C₄ growth. It was found that the introduction of Y-zeolite enhanced the adsorption capacity of the catalyst for most species. Moreover, the catalytic mechanism of the Co/Y catalyst was clarified, and we found that the introduction of the Y-zeolite mainly reduced the reaction energy barriers of the CH–CH coupling and C₂–C₄ carbon chain growth process, which also explained the high proportion of long carbon chain hydrocarbons in the Fischer–Tropsch synthesis products after Y-zeolite was introduced.