Preparation of ZrO₂ modified Al₂O₃ nano-sheets supported cobalt catalyst and its performance in Fischer-Tropsch synthesis

Al₂O₃ nano-sheet (Al₂O₃-CN) was synthesized under hydrothermal condition. The cobalt-based catalyst of 20% (mass fraction) was prepared by impregnation method and applied to Fischer-Tropsch synthesis. The Al₂O₃-CN (226 m²/g) and commercial alumina (Al₂O₃-C, 249 m²/g) have similar specific surface area, but Al₂O₃-CN has more narrow pore size distribution. Compared with Co/Al₂O₃-C catalyst, Co/Al₂O₃-CN catalyst showed higher reduction degree and more uniform cobalt particle size distribution after impregnation. Thus, Co/Al₂O₃-CN catalyst exhibited higher CO conversion and lower methane selectivity. In order to further improve the catalytic performance of Co/Al₂O₃-CN, Al₂O₃-CN was modified with ZrO₂. The characterization results showed that with the increase of ZrO₂, the specific surface of Al₂O₃-CN did not change significantly, and the pore volume and pore diameter increased. The cobalt particle size decreased and the number of active sites increased. Under the same reaction conditions, the CO conversion rate of catalysts modifield by ZrO₂ was farther improved and selectivity of methane was decreased.