CTL Technology Research Center, National Institute of Clean-and-Low-Carbon Energy, CHN Energy, Beijing, People's Republic of China.
Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands.
Nature. 2024 Nov;635(8037):102-107. doi: 10.1038/s41586-024-08078-5. Epub 2024 Oct 16.
Oil has long been the dominant feedstock for producing fuels and chemicals, but coal, natural gas and biomass are increasingly explored alternatives. Their conversion first generates syngas, a mixture of CO and H, which is then processed further using Fischer-Tropsch (FT) chemistry. However, although commercial FT technology for fuel production is established, using it to access valuable chemicals remains challenging. A case in point is linear α-olefins (LAOs), which are important chemical intermediates obtained by ethylene oligomerization at present. The commercial high-temperature FT process and the FT-to-olefin process under development at present both convert syngas directly to LAOs, but also generate much CO waste that leads to a low carbon utilization efficiency. The efficiency is further compromised by substantially fewer of the converted carbon atoms ending up as valuable C-C LAOs than are found in the C-C olefins that dominate the product mixtures. Here we show that the use of the original phase-pure χ-iron carbide can minimize these syngas conversion problems: tailored and optimized for the process of FT to LAOs, this catalyst exhibits an activity at 290 °C that is 1-2 orders higher than dedicated FT-to-olefin catalysts can achieve above 320 °C (refs. ), is stable for 200 h, and produces desired C-C LAOs and unwanted CO with carbon-based selectivities of 51% and 9% under industrially relevant conditions. This higher catalytic performance, persisting over a wide temperature range (250-320 °C), demonstrates the potential of the system for developing a practically relevant technology.
石油长期以来一直是生产燃料和化学品的主要原料，但煤、天然气和生物质正越来越多地被探索作为替代品。它们的转化首先生成合成气，即 CO 和 H 的混合物，然后再使用费托（FT）化学进一步加工。然而，尽管用于燃料生产的商业 FT 技术已经确立，但利用它来获取有价值的化学品仍然具有挑战性。一个典型的例子是线性α-烯烃（LAO），它是目前通过乙烯齐聚获得的重要化学中间体。目前商业的高温 FT 工艺和正在开发的 FT 制烯烃工艺都直接将合成气转化为 LAO，但也会产生大量的 CO 废物，导致碳利用率低。由于转化后的碳原子中很少有作为有价值的 C-C LAO 存在，而在占主导地位的产品混合物中的 C-C 烯烃中则存在大量的 C-C LAO，因此效率进一步受到影响。在这里，我们表明使用原始相纯的 χ-碳化铁可以最小化这些合成气转化问题：针对 FT 到 LAO 的过程进行了定制和优化，这种催化剂在 290°C 下的活性比专门用于 FT 到烯烃的催化剂在 320°C 以上所能达到的活性高 1-2 个数量级（参考文献），稳定 200 小时，在工业相关条件下产生所需的 C-C LAO 和不需要的 CO，碳基选择性分别为 51%和 9%。这种更高的催化性能在较宽的温度范围内（250-320°C）持续存在，表明该体系在开发实际相关技术方面具有潜力。
