Advances in iron-based Fischer-Tropsch synthesis with high carbon efficiency

Fischer-Tropsch synthesis (FTS) is an important technology for converting carbon-rich resources such as coal, natural gas, and biomass into clean fuels and high-value chemicals through synthesis gas. Iron-based catalysts are widely used in industrial applications due to their low cost and strong adaptability, especially for syngas derived from coal or biomass with low H₂/CO ratios. However, the catalytic process is complicated by frequent phase transformations among metallic iron, iron oxides, and iron carbides, which hinder mechanistic understanding and stability. Additionally, side reactions, such as CO disproportionation and the water-gas shift reactions, lead to excessive CO₂ formation, significantly reducing carbon utilization efficiency.

Iron-based catalysts exhibit complex and dynamic phase behavior during FTS, with iron carbides generally recognized as the primary active phases. Different iron carbide phases (e.g., ε-Fe₂C, χ-Fe₅C₂, and θ-Fe₃C) demonstrate distinct catalytic performances and readily interconvert under reaction conditions, critically influencing activity and product selectivity. In situ characterization has revealed the coexistence and transformation of multiple phases during operation, underscoring the importance of precise regulation to stabilize the most catalytically favorable phase.

To address high CO₂ selectivity and improve carbon efficiency, three key strategies have emerged:

ⅰ. Stabilization of phase-pure iron carbides, which prevents their oxidation into less active species like Fe₃O₄ and mitigates primary CO₂ formation; ⅱ. Hydrophobic surface modification, which reduces H₂O adsorption and thereby suppresses secondary CO₂ formation from the WGS reaction; ⅲ. Graphene confinement and 2D material encapsulation, which enhances the thermal and structural stability of active phases, tunes the electronic environment, and further inhibits CO₂-generating pathways. Together, these approaches offer a comprehensive framework for enhancing the stability and catalytic performance of iron-based FTS catalysts, enabling more efficient and sustainable FTS processes with reduced CO₂ emissions.

This review summarizes recent advances aimed at enhancing carbon efficiency in iron-based FTS catalysts. It highlights the critical role of constructing and stabilizing iron carbide active phases which critically influence catalytic activity, product selectivity, and phase dynamics under reaction conditions. Various strategies to suppress CO₂ formation including promoter addition, hydrophobic surface modification, and active phase stabilization, are critically examined for their effectiveness in improving carbon utilization. Particular attention is given to the application of two-dimensional materials, such as graphene, which enhance the thermal stability, sintering resistance, and electronic structure of iron carbides, thereby reducing CO₂ emissions and promoting selective formation of desired hydrocarbon products. This innovative approach offers new opportunities for developing catalysts with high activity, low CO₂ selectivity, and enhanced stability, which are key factors for enhancing both the efficiency and sustainability for FTS. Such advancements are crucial for advancing more efficient and sustainable FTS technologies, supporting the global push for net-zero emissions goals, and contributing to carbon reduction efforts worldwide.

The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(25)64738-3)

About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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