Supercritical fluids Fischer-Tropsch synthesis

K Yokota, Y Hanakata, K Fujimoto. Supercritical phase Fischer-Tropsch synthesis reaction. 3. Extraction capability of supercritical fluids. Fuel 70 989-994, 1991. 

Supercritical fluids (SCFs) offer several advantages as reaction media for catalytic reactions. These advantages include the ability to manipulate the reaction environment through simple changes in pressure to enhance solubility of reactants and products, to eliminate interphase transport limitations, and to integrate reaction and separation unit operations. Benefits derived from the SCF phase Fischer-Tropsch synthesis (SCF-FTS) involve the gas-like diffusivities and liquid-like solubilities, which together combine the desirable features of the gas- and liquid-phase FT synthesis routes. 

When a fluid is compressed and heated above the critical conditions (or to supercritical conditions, sc), the differences between gas and liquid disappear. For carbon dioxide, this occurs for temperatures above 31 °C and pressures above 7.3 MPa. For reactions (such as alkylations, aminations, hydroformylations, hydrogenations and Fischer Tropsch synthesis) occurring in supercritical fluids, the reaction rate is often increased dramatically because of improved desorption of heavy molecules minimizing the oxygen and hydrogen solubility limitations, improved heat transfer, and improved selectivity by a catalyst by minimizing pore diffusion limitations. 

Fan L, Fujimoto K. Fischer-Tropsch synthesis in supercritical fluid characteristics and application. Appl. Catal. A Gen. 1999 186 343-354. 

Elbashir NO, Bukur DB, Durham E, Roberts CB. Advancement of Fischer-Tropsch synthesis via utilization of supercritical fluid reaction media. AIChE J. 2010 56 997-1015. 

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