Enhanced Incorporation of α-Olefins in the Fischer−Tropsch Synthesis Chain-Growth Process over an Alumina-Supported Cobalt Catalyst in Near-Critical and Supercritical Hexane Media

Abstract

Operating Fischer−Tropsch synthesis (FTS) in supercritical fluid (SCF) media offers advantages over conventional gas-phase FTS operation including in situ extraction of heavy hydrocarbons from the catalyst pores coupled with enhanced incorporation of α-olefins in the chain growth process. In this study, hydrocarbon product distributions in near-critical and supercritical hexane phase FTS (SCH-FTS) was studied over a 15% Co/Al2O3 in a high-pressure fixed-bed reactor system. The critical point of the hexane−syngas−products reaction mixture as collected from the reactor outlet was measured using a variable-volume view cell apparatus. All reactions were carried out in near-critical and supercritical regimes by tuning either the reaction temperature (230−260 °C) or the reaction pressure (30−80 bar). Deviations from the standard Anderson−Schultz−Flory (ASF) chain growth model were observed in most cases; however, the degree of deviation depends on the reaction conditions within the near-critical and supercritic...