Abstract:

The Fischer-Tropsch (FT) synthesis is a key technology for producing high quality ultra-clean fuels from syngas produced from coal, natural gas, and biomass. Cobalt is one of the most effective and industrially important catalysts for the FT synthesis due to its high activity, high resistance to deactivation, and low water-gas shift activity. Although the cobalt-based catalysts for the industrial application have been developed, the large-scale and wide application of Co-based catalysts is still in need of developing a more efficient catalyst with a higher activity, improved stability, and higher selectivity to desired products such as α-olefins. In this work, the recent advances on the study of Co-based catalysts for FT synthesis, i.e., the structure sensitivity, breaking the dependence between the dispersion and extent of reduction of cobalt, deactivation mechanism, and tuning the product selectivity, are reviewed. The effects of Co particle size, crystal structure, and the interactions between Co and support on the FT activity are analyzed . Besides increasing the Co dispersion and extent of reduction through adjusting the interactions between Co and the support, the controlled synthesis of Co-based catalysts with a hexagonal close packed (hcp) phase, of which a higher intrinsic activity for FT synthesis has been revealed, is an effective strategy to improve the mass-specific activity of Co catalysts. The resistance to the sintering of Co and coke deposition is revealed as the key factor for improving the lifetime of Co-based catalysts for FT synthesis. Finally, recent developments of bifunctional FT catalysts for one-step synthesis of clean liquid fuels from syngas are highlighted, and the further developing trends are to improve the stability of bifunctional catalysts and to solve the engineering problems for large-scale manufacture of the catalyst.

Key words: Fischer-Tropsch synthesis, syngas, catalyst, deactivation, sintering, particle-size effect, Co-support interactions

摘要：

尽管Co基费-托（Fischer-Tropsch，FT）合成催化剂相对较为成熟，但高活性、高稳定性以及高α-烯烃等特定产物选择性Co基催化剂的研发，依然是FT合成过程更大规模工业化应用面临的重大挑战。本文总结分析了Co基FT合成催化剂的结构敏感性、分散度与还原度矛盾、催化剂失活以及产物选择性调控等方面的最新进展和动向。根据Co的尺寸、晶相结构及Co与载体间相互作用影响催化剂活性的规律，认为除通过调变金属载体间相互作用以提高Co的分散度和还原度外，设计制备具有更高本征活性的hcp相Co是提高其质量比活性的有效策略；而进一步提高工业Co基催化剂寿命的关键是抑制Co的烧结和积炭。最后，总结了合成气一步高选择性合成液体燃料的新进展，认为提高双功能催化剂的稳定性以及解决工程化制备问题是实现该过程工业化应用的关键。

关键词: 费-托合成, 合成气, 催化剂, 失活, 烧结, 尺寸效应, 钴-载体相互作用