Direct olefin production from coal gasification (the end of coal-to-methanol and methanol-to-olefins processes)

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　Recently, a team led by Academician Bao Xinhe and Researcher Pan Xiulian from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences (hereinafter referred to as the Dalian Institute), overturned the F-T route that has been used in coal chemical processing for over 90 years. By creatively utilizing syngas generated from coal gasification – a mixture of purified CO and H2 – and under the action of a novel composite catalyst, they achieved the production of low-carbon olefins through a single-step reaction with high selectivity. The research findings were published on March 4 in the American journal Science, and a Chinese invention patent as well as an international PCT patent have been filed for this reaction process. This achievement has been hailed by peers as a \"milestone breakthrough in the field of coal conversion.\" The research related to this achievement was funded by **the National Natural Science Foundation of China (21321002, 21425312, 21222305, 91545204) and other sources. 　　German scientists Fischer and Tropsch invented the F-T process in 1923, which uses coal and syngas to produce high-carbon chemicals and liquid fuels. Although this process is not perfect – for example, it produces large amounts of carbon dioxide, consumes a lot of water, has poor product selectivity, and requires significant energy for subsequent processing – the international energy and chemical industries continue to consider it irreplaceable. Today, this process has been overturned by researchers at the Dalian Institute of Chemical Physics—they abandoned the water-gas shift hydrogen production method, which is characterized by high water and energy consumption, and instead used the mixed gas produced by coal gasification (after purification) to obtain low-carbon olefins with high selectivity. When the one-way conversion of CO is 17%, the selectivity for low-carbon hydrocarbon products reaches 94%, with the selectivity for low-carbon olefins (ethylene, propylene, and butylene) exceeding 80%. It broke the limit of the traditional Fischer-Tropsch synthesis process, where the selectivity for low-carbon olefins was at most 58% (the Schulz-Flory limit). 　　The traditional F-T process uses metals (in reduced form) as catalysts. On the surface of metal catalysts, CO molecules are activated and dissociated into C atoms and O atoms. These C and O atoms react with hydrogen adsorbed on the catalyst surface to form methylene (CH2) intermediates, while water molecules are released. The methylene intermediates undergo free polymerization on the catalyst surface through a migration insertion reaction, yielding hydrocarbon products with different numbers of carbon atoms (ranging from one to thirty, and sometimes even up to hundreds of carbon atoms). The carbon atom number distribution of the hydrocarbon products in the entire reaction is wide, resulting in low selectivity for the target product. At the same time, this process requires a large amount of hydrogen to remove the O atoms generated by the dissociation of CO on the surface of the metal catalyst, and this valuable hydrogen is obtained through water-gas shift reaction (CO + H2O → H2 + CO2). The water-gas shift reaction is an energy-intensive process that also results in the release of large amounts of CO2. The process developed by researchers at the Dalian Institute of Chemical Physics uses partially reduced composite oxides as catalysts. CO molecules adsorb onto the oxygen-deficient sites of these catalysts and dissociate; gaseous hydrogen molecules then react selectively with the resulting C atoms to form methylene radicals. Meanwhile, the oxygen atoms generated from the dissociation of CO on the catalyst surface tend to react with another CO molecule, forming CO2. Unlike the traditional F-T process, the methylene radicals generated at oxygen-deficient sites do not remain on the catalyst surface or undergo surface polymerization reactions; instead, they quickly enter the pores of the molecular sieve, where they undergo selective coupling reactions in a confined pore environment to produce low-carbon olefins, thereby **increasing the selectivity of the products**. By regulating the pore structure and acid properties of molecular sieves, the product molecules can be controlled and modified. 　　This breakthrough eliminates the excess oxygen atoms in hydrocarbon formation by using CO instead of H2, thereby eliminating the energy- and water-intensive water-gas shift reaction. Without altering the total CO2 emissions, it opens up a new approach to coal conversion that requires low water consumption (with no water circulation in its structure). At the same time, by creatively combining oxide catalysts with molecular sieves, it was possible to effectively separate the two catalytic active centers responsible for CO activation and intermediate coupling. The \"free radicals\" that arise in traditional Fischer-Tropsch processes in a random and uncontrolled manner were confined within a \"cage\" (the molecular sieve); by restricting their behavior, they were transformed into the desired target products (low-carbon olefins). It overcomes the trade-off dilemma of activity and selectivity in traditional catalytic reactions, providing a guide for the design of efficient catalysts and catalytic processes. 　　The process of this new invention not only helps save water and reduce CO2 emissions in terms of manufacturing processes (by shortening procedures and lowering energy consumption), but it also offers significant economic benefits. According to the preliminary assessment by Sinopec Engineering Construction Co., Ltd. (SEI), under the current conditions, the internal rate of return (IRR) for this project can exceed 14%. Many chemical companies, both domestic and international, are very interested in the further application and promotion of this process. Following thorough evaluation and discussions, the Dalian Institute of Chemical Physics has now reached preliminary agreements with major domestic chemical enterprises as well as renowned foreign chemical companies to collaborate on areas such as catalyst preparation and process development, with the aim of achieving industrial demonstration and commercialization as soon as possible, and striving to turn this original achievement into real productive capacity. 　　For this single study alone, the team spent over nine years working in collaboration with various research institutions in China, including the Hefei Synchrotron Radiation Facility, and utilized a variety of high-end research devices developed by them own.