Overview of Adipic Acid Diamine (HMD) Products

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Overview of Hexamethylenediamine (HMD) Products I. Overview Hexamethylenediamine (HMD), with the molecular formula C₆H₁₆N₂ and a molecular weight of 116.20, is a straight-chain aliphatic diamine that contains two amino functional groups. Appearance: At room temperature, it appears as colorless crystals or a transparent liquid, with a strong ammonia odor. Melting point: 42–45°C, boiling point: 204–205°C, density: 0.89 g/mL. Soluble in water and alcohol, slightly soluble in benzene and ether. It is an important organic chemical intermediate, widely used in fields such as nylon, epoxy resins, and fuel additives. II. Production Process: The production processes in the latter half are basically similar, both involving the hydrogenation of adiponitrile to produce adipamide. The process for producing adiponitrile in the first half varies, giving rise to the following methods: 1. The mainstream process (accounting for 95% globally) (1) Adiponitrile hydrogenation method (accounting for 90% in China): The direct hydrocyanation of butadiene was developed by the American company DuPont in the early 1970s; it replaced the previous method of chlorination of butadiene with hydrogen chloride, and offers advantages such as lower costs, reduced energy consumption, and less corrosion to equipment. The direct cyanation of butadiene uses transition metal (nickel, ruthenium, rhodium, etc.) complexes as catalysts, and proceeds in three steps at certain temperatures and pressures: ① primary cyanation, ② isomerization, ③ secondary cyanation. Process: Butadiene + Hydrocyanic acid → Pentenonitrile → Adiponitrile → Hydrogenation → Adipamide. Advantages: low raw material costs, short processing time, low energy consumption, and high product purity (99.9%+) ； Disadvantages: Hydrogen cyanide is highly toxic, and the catalyst is complex. Representatives: Nvidia (60% globally), Tianchen Qixiang (China’s first plant with a capacity of 200,000 tons per year, put into operation in 2022). (2) Acrylonitrile electrolytic dimerization method: This method was first developed and successfully applied by the American company Monsanto in the 1960s; later, the Japanese company Asahi Kasei also mastered this technology. Chernor Company (formerly part of Monsanto) sold this technology to the American company Oxide. Electrolytic hydrogenation dimerization is used to produce adiponitrile; initially, the diaphragm electrolysis method was employed, but it was gradually replaced by the membraneless electrolysis method. Diaphragm electrolysis is divided into the solution method and the emulsion method. Monsanto was the first to use the solution method in its development, while later, the Japanese company Asahi Kasei developed the emulsion method based on Monsanto’s work. The dimerization of acrylonitrile requires high energy consumption, leads to high equipment investment, and generates large amounts of carbon dioxide emissions, posing environmental challenges. This process involves numerous side reactions; during the electrolysis process, substances such as propionitrile, polymers, and 2-methylglutaronitrile are formed. Furthermore, the electrolytic method inevitably produces oxygen, posing certain safety risks to the process. The overall comprehensive production cost of hexanitrylene produced by the acrylonitrile method is higher than that of the butadiene method; the latter has already been manufactured domestically, with only a few companies using it. Production capacity is low. Process: Acrylonitrile → Electrolytic dimerization → Adiponitrile → Hydrogenation → Adipamide. Representatives: Oxyden, Asahi Kasei, Shanxi Runheng. 3) Ammonolysis of adipic acid: First developed by the French company Rhône-Poulenc; subsequently, companies such as Monsanto in the United States, Radici in Italy, and BASF in Germany also succeeded in developing this method and putting it into use. In the 1970s, the Liaoyang Petrochemical Branch in China introduced a complete set of adipic acid production facilities from the French company Rhodia. The adipic acid method is divided into the liquid-phase method and the gas-phase method. The liquid-phase method has been phased out due to poor product quality and low yields. The vapor phase method is divided into two types: the BASF method and the Monsanto method. The disadvantage of the adipic acid process is the presence of many by-products, and the product quality is generally poor; this method is highly influenced by the price of adipic acid. Process: Adipic acid → Amination and dehydration → Adiponitrile → Hydrogenation → Adipamide. Disadvantages: High temperature and pressure, high energy consumption, numerous by-products, and high costs (15%-20% higher than the butadiene method). Representative company: Huafeng Chemical (which operates the entire industrial chain from adipic acid to adipamide and adipamine). (4) Caprolactam amination method: An original Chinese innovation; companies such as Sinochem Yangnong, Tianchen, Shenma, and Xuyang have developed independent domestic technologies for this process. Process: Caprolactam → Amination → Aminocapronitrile → Hydrogenation → Adipic acid. Advantages: Avoids the use of capronitrile; raw materials are readily available (there is an overcapacity for caprolactam in China); less waste generation; high yield. Representatives: Sinochem Yangnong (the world’s first industrial facility with a capacity of 10,000 tons per year, producing 40,000 tons of nylon 66 and 25,000 tons of adipic acid); Pingmei Shenma (capacity of 100,000 tons per year, scheduled to come online in 2025)