A new approach to the domestic production of adiponitrile has been developed: a two-step process using methanol and butadiene, which has been evaluated

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New progress has been made in the technology crucial for the development of China’s nylon 66 industry – the production process of adiponitrile. On April 30, the two-step process for producing adiponitrile using methanol and butadiene, developed by Beijing Daosike Mining Equipment Technology Co., Ltd., a wholly-owned subsidiary of Buzun Investment Group, passed the evaluation of scientific and technological achievements organized by the China Chemical Information Center. The evaluation panel, composed of Zhang Liqun, an academician of the Chinese Academy of Engineering and vice president of Beijing University of Chemical Technology, and Yue Guangxi, an academician of the Chinese Academy of Engineering and professor in the Department of Thermal Energy Engineering at Tsinghua University, believes that the new process features significant innovations, with its key technologies reaching international leading levels; they recommend accelerating its industrial application. 　　“The new two-step process for producing adiponitrile that we have developed uses methanol or calcium carbide off-gases, which are available in large quantities in China, as raw materials. Hydrogen cyanide is obtained sequentially through a formamide production unit and a hydrogen cyanide production unit; this hydrogen cyanide then reacts with butadiene via primary and secondary cyanation processes. 80%~90% of the product is adiponitrile, while 10%~15% is 2-methylglutaronitrile (MGN) as a by-product. We also have an excellent process for utilizing 2-methylglutaronitrile: it can be hydrogenated to produce 2-methylglutamic acid, which is then subjected to cyclization and dehydrogenation reactions to yield 3-methylpyridine of high added value, used in the production of vitamins and pharmaceutical intermediates. "Ying Guohai, the chief engineer of Platinum Elite Investment Group, introduced the technical approach of the new process as well as the research achievements obtained. 　　After reviewing the presentation, the expert group concluded that the new process has achieved three innovations in terms of the overall technological framework and key equipment: first, it develops process technologies for producing methyl formate from methanol, formamide from ammonia, and hydrocyanic acid through high-temperature pyrolysis, including a unique microheat exchanger technology, MnO/SiO₂ non-precious metal catalysts, as well as energy-efficient separation and purification techniques. The selectivity for hydrocyanic acid exceeds 94%, with a purity of 99.95%. This hydrocyanic acid production unit is the first of its kind in China. Second, a highly active and selective ligand catalyst system was developed independently, with a ligand concentration of 95%, thereby breaking through foreign patent restrictions. Thirdly, a new production process and a set of equipment for the two-step synthesis of adiponitrile were developed; the overall yield of adiponitrile and the by-product MGN in the pilot plant was over 95%, with the adiponitrile concentration reaching 99.6%. The expert group believes that the overall energy consumption of this set of technical equipment is lower than the industry average, which can effectively reduce construction costs and operating expenses, offering a new approach for the domestic production of adiponitrile. 　　“The methanol, which is used as the raw material in this new process, can be either methanol produced from coal or one manufactured from calcium carbide exhaust gases. This new process represents a good solution for addressing the surplus supply of methanol in the country, enabling the comprehensive utilization of calcium carbide exhaust gases, and facilitating the transition from coal chemical industry to the production of fine chemicals derived from coal. Previously, we completed the design and construction of a pilot plant for hexanitrocinene with a capacity of 500 tons per year. The plant operated stably for 168 hours, and both the process conditions and operational results met the design specifications. Currently, a 10,000-ton capacity facility for adiponitrile and related high-end new materials is set to be constructed at the Ningdong base; once completed, it will fill the gap in the nylon industry there. ” Geng Haitao, chairman of Platinum Elite Investment Group, said. 　　It is understood that hexanitronic acid is a key intermediate in the production of nylon 66, and it is primarily used to manufacture the nylon intermediate hexamethylenediamine. In recent years, despite the continuous growth in demand for nylon 66, the industry for this material operates on a global scale under an oligopolistic structure, and the key factor here is the availability of the raw material, hexanitronic acid. Due to the reliance on the key raw material adiponitrile, China’s dependence on imported nylon 66 amounts to nearly 30%, and the production of adiponitrile has become a critical bottleneck in the field of new materials in China. In 2019, the **National Development and Reform Commission classified 10,000-ton capacity adiponitrile production facilities as projects that deserve encouragement, in order to advance the localization of adiponitrile production technology. The new two-step process for producing adiponitrile developed by Daosike Company, along with the 10,000-ton industrial production facility planned to be built at the Ningdong site, have opened up a pathway for the transition from coal chemical industry to coal-based fine chemical industry, thereby creating an industrial chain that goes from coal chemicals to high-end fine chemicals and features complete independent intellectual property rights.