After decades of research and development, the Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences has pioneered internationally leading coal-to-liquid (CTL) technology, achieving large-scale industrial application with an annual capacity of 6.7 million tons. This has significantly contributed to national energy security and sustainable development. In the primary products of CTL technology, α-olefins account for more than 50%, with the annual production capacity of medium and long-chain α-olefins (C6+) reaching hundreds of thousands of tons. These are high-quality chemical raw materials that are difficult to obtain directly from petrochemicals. However, due to the similar properties of hydrocarbons with close carbon numbers, separating α-olefins directly is very challenging and costly. Currently, they can only be hydrogenated into oil products, leading to a massive waste of high-quality resources. The research team led by Prof. Cao Zhi at the Shanxi Institute of Coal Chemistry has proposed the directed transformation of medium and long-chain α-olefins from CTL crudes into high-carbon number aldehydes via hydroformylation. This not only achieves high-value utilization of primary CTL products but also reduces the difficulty of separating products with similar carbon numbers.

Prof. Cao Zhi’s team recently proposed a new strategy for achieving ultra-high regioselectivity in olefin hydroformylation. The related research was published in the Nature (https://www.nature.com/articles/s41586-024-07342-y). More recently, in collaboration with Tsinghua University and Synfuels China Technology Co., Ltd., the team extended this system to the hydroformylation of medium and long-chain α-olefins. By precisely encapsulating sub-nanometer rhodium clusters within the sinusoidal channels of pure silica MFI zeolite, they developed a new type of supported Rh catalyst, which achieved over 99.7% regioselectivity for the desired linear aldehyde products in the hydroformylation of C6-C12 α-olefins, surpassing all previously reported heterogeneous catalysts and most homogeneous catalysts developed thus far. Utilizing advanced characterization techniques such as aberration-corrected transmission electron microscopy, in situ X-ray absorption spectroscopy, and infrared spectroscopy, the team elucidated the distribution and local fine structure of rhodium clusters within the zeolite pores. First-principles calculations were employed to revealed the synergistic effect between Rh clusters and the zeolite framework and clarified the intrinsic mechanism for the directed formation of linear aldehyde products. This research not only provides an innovative approach for designing efficient, high-selectivity catalysts for hydroformylation of long-chain α-olefin but also offers new insights for the targeted synthesis and catalytic application of porous materials encapsulated metal clusters.

The related research findings were published in Nature Catalysis on May 15th. This work was supported by the National Key R&D Program, the National Natural Science Foundation of China, and research funds from Synfuels China Technology Co., Ltd.

Link to the paper：https://doi.org/10.1038/s41929-024-01155-y