Enhanced formation of α-olefins by the pulse process between Fischer-Tropsch synthesis and N₂ purging

The Fischer-Tropsch synthesis has offered an alternative way to convert coal and biomass into chemicals such as α-olefins via sygas comprised of H₂ and CO. A pulse process switching between Fischer-Tropsch synthesis and N₂ purging was carried out when the Fischer-Tropsch synthesis became stable in the fixed bed reactor. The activity and selectivity over Fe-Co catalyst for α-olefins in Fischer-Tropsch synthesis reaction were measured under the normal conditions of 2.0 MPa, 497 K, 2 000 h^-1 and H₂/CO volume ratio of 2.0. It was found that the olefin to paraffin ratio of C₃ for Fe-Co catalyst purged at 517 K and 0.2 MPa was almost nine times higher than that of the fresh one without purging under the same reaction conditions, and the CH₄ selectivity and CO conversion decreased after purging. Two possible reasons were proposed to explain these phenomena. Moreover, a batch experiment by the pulse process in fixed bed reactor was performed. Notably, a high olefins yield was obtained via the pulse process during the Fischer-Tropsch synthesis.