Hexamethylene diamine is an important chemical intermediate, mainly used in the preparation of nylon 66, nylon 610, can also be used in the preparation of HDI, polyurethane resin, curing agent. Nylon 66 is an important downstream product of hexamethylenediamine, which is prepared by polycondensation of hexamethylenediamine and adipic acid. It is widely used in chemical fiber industry, clothing textile industry, electronic equipment and aerospace industry. Especially with the rapid development of the new energy automobile industry, nylon 66 consumption will continue to grow in the future, and it is a high boom track in the field of new materials in China.
1. Adiponitrile method
At present, the methods for large-scale production of Hexamethylene diamine are adiponitrile process. The reaction mechanism is that under the action of a certain temperature, pressure and catalyst, adiponitrile and hydrogen gas undergo addition reaction to produce adiponediamine.
The reaction equation is:
The process is divided into two kinds: high pressure method and low pressure method. Depending on the catalyst, the high-pressure method is divided into two types. One is an iron-based catalyst with a reaction pressure of 30 ~ 35Mpa and a reaction temperature of 100 ~ 180℃. The other is a cobalt-copper catalyst, which has a higher reaction pressure requirement of 60 ~ 65Mpa and a reaction temperature of 100 ~ 135℃. The high pressure method uses three-phase fluidized bed as the reactor type, liquid ammonia and toluene as the solvent, and the selectivity is as high as 90% ~ 95%.
The low pressure law uses nickel-based catalyst, the reaction pressure is 1.8 ~ 3.0Mpa, and the reaction temperature is 60 ~ 100℃. The low pressure method uses ethanol as solvent and strong base compound as cocatalyst to improve the activity of catalyst. Hexamethylenediamine with 99% purity can be obtained by low pressure purification.
2. Adipic acid method
The core of this method is to take adipic acid and ammonia gas as raw materials, ammoniate to produce ammonium adipate and water, ammonium adipate to dehydrate at high temperature to produce adipdinitrile, and adipdinitrile to react with hydrogen gas to produce adipdiamine.
Adipic acid method mainly includes gas phase method and liquid phase method. Compared with the gas phase method, the liquid phase method has lower reaction temperature, less damage to the catalyst, less by-products and higher yield, so the liquid phase method is mainly used for adipate ammonification.
3. Caprolactam method
The method uses caprolactam as raw material and phosphate as catalyst. The reaction mechanism is that caprolactam reacts with ammonia gas to dehydrate into aminocapronitrile, and aminocapronitrile reacts with hydrogen gas at high temperature to produce Hexamediamine. The yield of this method is very high, the raw material caprolactam can be obtained from the defective nylon 6, which is an environmentally friendly process.
4. Hexanediol method
Hexamethylenediamine (Hexamethylenediamine) was synthesized from 1, 6-hexamethylene glycol (Hexamethylene glycol) as raw material and nickel as catalyst under high temperature and pressure.
There are many side reactions in this method, and alkaline compounds are usually used as cocatalysts to inhibit the side reactions, and the by-products are recycled into the ammonification process to improve the yield.
5. Butadiene method
At a certain temperature and pressure, 1, 3-butadiene reacts with hydrocyanic acid to form pentenitrile, which then reacts with hydrocyanic acid to form adipic dinitrile, which reacts with hydrogen gas to produce adipic diamine. The method was developed on the basis of 1, 3-butadiene preparation of adiponitrile.
In recent years, the state has introduced various policies to encourage the overcoming of "jam neck" technical problems, and more and more domestic independent research and development of Hexamethylene diamine production processes have been developed, and hexamethylene diamine projects under construction have also sprung up. Shandong Desen Lai will take the "domestic hexamethylene diamine" ride, lead the release of adipic acid production capacity, and promote the high-quality development of nylon 66 new material industry.
In recent years, the state has introduced various policies to encourage the overcoming of "jam neck" technical problems, and more and more domestic independent research and development of Hexamethylene diamine production processes have been developed, and hexamethylene diamine projects under construction have also sprung up. Shandong Desen Lai will take the "domestic hexamethylene diamine" ride, lead the release of adipic acid production capacity, and promote the high-quality development of nylon 66 new material industry.