An active and selective production of gasoline-range hydrocarbons over bifunctional Co-based catalysts

Catalytic performance of several bifunctional cobalt-based catalysts in slurry-phase Fischer–Tropsch synthesis has been investigated at 1 MPa and 230 °C. The catalysts were prepared according to the conventional impregnation method using SiO2, Al2O3, montmorillonite (K10®), and various zeolites (USY, ZSM-5 and MCM-22) as a support. When an acidic support was applied, the formation of heavier hydrocarbons was retarded and the carbon number distribution was shifted to gasoline range (C4–C12). Montmorillonite loaded with Co (Co/MONT) was a good catalyst, showing higher the CO conversion than Co/SiO2 and Co/Al2O3. MCM-22 exhibited a superior performance to other zeolitic supports. With decreasing aluminum content, the activity of Co/MCM-22 catalysts was remarkably enhanced and the selectivity to methane and isoparaffins decreased. Besides the high CO conversion (55–60%), C4+ isoparaffins were produced more selectively over Co/MCM-22 (43–53%) than Co/USY (43.5%) and Co/ZSM-5 (36%). Compared to the results under supercritical conditions, the slurry-phase conditions are more suitable for an active and selective production of gasoline-range hydrocarbons through the Fischer–Tropsch synthesis over MCM-22 supported Co catalysts.