【Ten Years of Rapid Development in Chemical Equipment】Pilot-scale testing completed for the process of producing succinic acid via the catalytic hydrogenation of maleic anhydride in aqueous medium from 2013 to 2023

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On November 27, 2023, the pilot-scale test lasting 8,000 hours was completed for the process of producing succinic acid via the catalytic hydrogenation of maleic anhydride in an aqueous medium, a method jointly developed by the Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences and Xinjiang Tianye (Group). Production methods of succinic acid: The main production methods for succinic acid include chemical synthesis, biological fermentation, and electrolysis. The electrolytic method uses maleic anhydride as a raw material for the electrolytic reduction to produce succinic acid. Through development, the electrolytic synthesis technology and processes have become quite mature; it features high electrolytic yields, current efficiencies, and conversion rates, enabling the production of high-purity succinic acid. The biological fermentation method involves using starch, cellulose, glucose, sucrose, milk, or other waste materials that can be utilized by microorganisms as raw materials, and employing bacteria or other microorganisms for fermentation in order to produce succinic acid and its derivatives. The maleic anhydride hydrogenation method involves dissolving maleic anhydride in a solvent, subjecting it to hydrogenation, and then obtaining maleic anhydride through distillation; this compound is subsequently hydrolyzed to yield succinic acid. Advantages and prospects of the aqueous-phase method: Compared with current methods such as electrolysis, biological fermentation, and maleic anhydride solvent hydrogenation, the aqueous-phase method for producing succinic acid features a shorter production process, lower energy consumption, and no generation of hazardous waste, thereby enabling a significant reduction in the production costs of succinic acid. During the operation of the 10-ton pilot plant, the conversion rate of maleic acid is ≥99.9%, the selectivity for succinic acid is ≥99.9%, the purity of the resulting succinic acid is ≥99.9%, and the amount of succinic acid produced per ton of catalyst is ≥10,000 tons; moreover, the solvent water can be recycled. This succinic acid pilot product was supplied to downstream manufacturers for testing, enabling the production of high-quality biodegradable material PBS. Polybutylene succinate (PBS), synthesized from succinic acid and 1,4-butanediol, is considered to have the best overall performance among various biodegradable plastics. Currently, the high production cost of succinic acid results in expensive PBS prices, which severely limits the widespread use of PBS. The aqueous-phase catalytic hydrogenation method using maleic acid is currently the most promising approach for the industrial synthesis of succinic acid. It offers advantages such as high conversion rates, simple separation, high product purity, and no significant side reactions, thus opening up a new route for the low-cost production of succinic acid. At present, Hunan Changlian New Materials Technology Co., Ltd. also has a pilot-scale plant for the production of succinic acid via aqueous hydrogenation. Xinjiang Tianye is building a project to produce 15,000 tons of succinic acid. Based on pilot-scale tests, Xinjiang Tianye Xiangtai New Materials Co., Ltd., a wholly-owned subsidiary of Xinjiang Tianye, plans to invest 275.5753 million yuan in order to establish a new facility for the green synthesis of succinic acid with an annual production capacity of 15,000 tons. The project received approval for environmental impact assessment in July 2023. Once all the project constructions are completed, an annual production capacity of 100,000 tons will be achieved; the investment required for this project is estimated to be 1 billion yuan. The designed annual consumption of succinic anhydride for this project is 12,456 tons per year, and the succinic anhydride is purchased from external suppliers. It mainly comes from Karamay Jinyuan Fine Chemicals Co., Ltd. (Karamay City, Xinjiang) and Xinjiang Kailianjie Petrochemical Company (Luntai County, Xinjiang). The designed annual hydrogen consumption for this project is 3,428,992 m3 per year. The hydrogen is supplied by Tianye Huihe New Materials Co., Ltd., whose 600,000-ton ethylene glycol production facility is located about 100 meters to the east of the project site. The catalyst used in the project was jointly developed and supplied by Xinjiang Tianye (Group) Co., Ltd. and the Shanxi Coal Chemistry Research Institute of the Chinese Academy of Sciences, with an annual consumption of 3 tons of hydrogenation catalyst. It is reported that this catalyst overcomes the limitations of existing catalyst preparation techniques, addresses the challenge of heat removal during reactions, and solves the problems associated with high costs, high pollution, and small production scales in current processes. This technology won the third prize in the startup category of the 12th China Innovation and Entrepreneurship Competition in 2023.