Abstract: The effect of using polar liquid as the reaction medium for Fischer-Tropsch synthesis on the product distribution was studied. The experiments were performed with an industrial iron-based catalyst in a batch autoclave reactor with different liquid phases (polyethylene glycol 400, polyethylene glycol 600, 1,4-butanediol, and glycol). The reaction conditions were temperature of 200–240 °C, initial H₂/CO molar ratios of 1.00–2.03, catalyst particle sizes of 20–40 mesh and > 150 mesh, and reaction time of 24–144 h. The α-olefin selectivity was significantly increased to more than 70% and was almost independent of carbon number with all the polar liquids. Most of the hydrocarbon distribution were not of the ideal Anderson-Schulz-Flory pattern and could not be explained by the mechanism of olefin readsorption and secondary reactions. The chain growth probability α was larger than 0.85 for all conditions, and it was slightly influenced by changes of reaction conditions, liquid, and reaction time. There was product separation during reaction in this catalytic system, which meant that it did not have the problem of separating the catalyst from the wax product that traditional slurry reactors have. The result suggested new opportunities for the selective production of linear α-olefins and for mechanistic investigations of Fischer-Tropsch synthesis.

Key words: Fischer-Tropsch synthesis, α-olefin selectivity, reaction medium, polar liquid, polyethylene glycol, product distribution, secondary reaction