【Frontiers in HaiChuan Chemical Technology】Trace halogens enable “zero-carbon emission” olefin production via Fischer-Tropsch synthesis

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Trace halogens enable “zero-carbon emission” olefin production via Fischer-Tropsch synthesis – Source: [Peking University] 1. Research background: The Fischer-Tropsch synthesis can convert syngas (carbon monoxide and hydrogen) into liquid fuels or high-value chemicals such as olefins, and it plays a key role in the production of oils and high-value chemicals from carbon sources such as coal, natural gas, and biomass. Due to their advantages such as low cost and high space-time yield of oil products, iron-based catalysts currently account for over two-thirds of the global FTO synthesis capacity. In China, all Fischer-Tropsch synthesis industrial processes use iron-based catalysts. However, the \"inherent weaknesses\" of the iron-based Fischer-Tropsch synthesis process are also very prominent: during the reaction, water-gas shift (WGS) and the Boudouard reaction occur easily, resulting in CO2 with a selectivity of 18-35%. This not only leads to significant carbon dioxide emissions but also wastes valuable carbon resources. In industrial processes, even with recycle gas engineering measures, the CO2 selectivity generally remains above 16%. 2 Research Content A groundbreaking research finding was recently published in the journal Science: a research team led by Professor Martin from the School of Chemistry and Molecular Engineering at Peking University and Researcher Wen Xiaodong from the Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences has developed a simple-to-use yet highly effective catalytic control strategy. This strategy enables the near-complete elimination of carbon dioxide as a by-product during Fischer–Tropsch synthesis (FTS), while significantly improving the selectivity for oils or olefins. It offers a new approach for the green conversion of syngas and the production of low-carbon chemicals. By introducing bromomethane (CH3Br) at a concentration of one part per million (ppm) into the syngas, the research team achieved precise control over the reaction pathways on the surface of the iron-based catalyst. Experimental results show that bromomethane at the ppm level is sufficient to shut down the reaction pathway leading to CO2 formation; the selectivity for CO2 production drops from around 30% in traditional cases to less than 1%, achieving almost \"zero emissions\"” ； At the same time, the selectivity for the target product—olefins—increased significantly to around 85%, while the olefin/alkane ratio reached about 13. This strategy not only resolves the issue of high CO2 by-product formation, which has long plagued iron-based FTS, but also overcomes the technical barrier that makes it difficult to achieve high space-time yields of olefins alongside low carbon emissions. https://p3-sign.toutiaoimg.com/tos-cn-i-axegupay5k/fce002b3914f4d6ba3273c6671b75ae2~tplv-tt-origin-web:gif.jpeg?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1765166799&x-signature=aLHeQ5YaZn5wrgHPvg4z0aueyGY%3DFigure 1| Effect of halogen co-feed on the performance of Fischer-Tropsch synthesis. Researcher Wen Xiaodong said, “Our work demonstrates that it is possible to achieve selective suppression of certain reaction pathways within complex catalytic networks by using trace amounts of ‘poisons’ for regulation.” This strategy does not involve reengineering new materials, but rather introducing lightweight yet efficient dynamic tuning factors onto the surface of existing catalysts. It is this ‘plug-and-play’ type of regulation that enables us to efficiently ‘turn off’ the side reaction pathways, thereby greatly improving the efficiency of carbon atom utilization in the reaction. ”“The Fischer-Tropsch synthesis has always been a key pillar of China’s coal chemical and syngas-based industries, but the issue of CO2 by-product generation is one of the biggest challenges to its green transformation. ”Professor Martin explained, “Our work provides a simple and effective technical solution for achieving the production of green, low-carbon olefins or petroleum products.” If combined with the use of green hydrogen and coal gasification processes with low CO2 emissions, this technology can offer new opportunities for decarbonizing coal chemical processes that are crucial to China’s energy security. This research was published in the journal Science under the title “Trace-level halogen blocks CO₂ emission in Fischer–Tropsch synthesis for olefins production”. This achievement quickly attracted significant attention and positive evaluations from the international academic community. A perspective article titled “Two diverging paths for clean fuel” published in the same issue of Science covered this topic. Meanwhile, Science featured a special report on this research in its news section under the title “Chemical additive slashes carbon emissions when creating synthetic fuels: Advance in Fischer-Tropsch process could make coal-to-liquid plants cleaner”. Chemical & Engineering News of the American Chemical Society also covered this work, stating that it is “a surprising, important finding” and “a breakthrough achievement!” ”(This is a breakthrough work). Chemistry World of the Royal Society of Chemistry reported that \"the formation of carbon dioxide is nearly completely suppressed, coupled with a selectivity of up to 85% for the olefin products, making it an extremely exciting breakthrough.\" “It’s conceptually innovative and exciting” (The near total suppression of carbon dioxide production, coupled with the impressive 85% selectivity for olefin products, represents an extremely encouraging advancement. This is conceptually new and exciting). 3 Author information: The corresponding authors of the paper include Professor Martin from Peking University, Researcher Wen Xiaodong and Dr. Liu Xingwu from the Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences. Professor Liu Xi from Ningxia University, Cai Yi, a doctoral student at the Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences, Wang Maolin, a former doctoral student from Peking University, Xie Junzhong, a doctoral student, and Zhao Shu from Beijing University of Technology are the co-first authors. This research was funded by projects such as the **Key Research and Development Program**, the National Natural Science Foundation, the **Outstanding Young Scientist Fund**, the New Foundation Researcher Program, and the Beijing Molecular Science **Research Center**. Layout | Guo Yulin