[Coal Chemical Industry] It's time to restart the process of adipic acid ammoniation to adiponitrile

At present, the market price of adipic acid has dropped by 12,000 yuan (ton price, the same below) compared to the highest price in more than ten years, which highlights the competitiveness of the adiponitrile production plant that has been suspended for many years.

Ammonia reaction is mainly liquid phase

The reaction of adipic acid and ammonia first produces ammonium adipate, which is dehydrated and converted to amide, and the amide is continuously dehydrated to form adiponitrile.

The production process of adipic acid ammoniation is mainly divided into gas phase method and liquid phase method.

In the gas phase method, adipic acid is heated and gasified first, and then reacted with ammonia gas.

The liquid phase method is to melt adipic acid under the condition of 200℃~300℃, react with ammonia gas in the presence of a catalyst, and then dehydration, deweight, chemical treatment and vacuum distillation to obtain higher purity The yield of adiponitrile is 90%~94%.

Overcapacity prices cut in half

The production process of adiponitrile produced by adipic acid amination method was successfully developed by the French Rhone Planck in the late 1960s.

At that time, the domestic production capacity of adipic acid was only about 150,000 tons.

At the same time, the market price of adipic acid has gradually declined from the highest level of 21,000 yuan in April 2011, reaching the highest price of 13,000~13,500 yuan in the past six years at the beginning of 2018, and then fell to 8,600~8,700 yuan in late March this year.

Optimized design for technology elimination

The raw materials account for more than 80% of the production cost of adiponitrile, which plays a decisive role in the economics of the adipic acid amination process.

After years of production optimization, Liaoyang Petrochemical’s adiponitrile plant has accumulated long-term stable operation technology and operating experience.

Restarting the research and development of the adipic acid ammoniation process requires elimination, optimization and redesign.

The reaction of adipic acid amination is complicated, the temperature of the pipe section is high, and the side reactions are many, which leads to a lot of impurities in the product and the quality of the product is reduced, and the coking and corrosion of the reactor are serious.

It can be explored to improve the design by connecting a bubbling pre-reactor in series in front of the reactor, increasing the volume of the neutralization section and the reaction time of adipic acid through the bubbling tower of the pre-reactor in series, and setting a sieve in the pre-reactor to disperse the bubbles.

The liquid acid catalyst can be dissolved in the reaction solution to achieve a better catalytic effect.

In addition, coking and corrosion in the dehydration section of the reactor are largely due to the use of liquid phosphoric acid catalysts in the adipic acid amination process.

The process of adipic acid amination reaction can explore the use of solid phosphoric acid catalyst.

(Keyword: Restart of nitrile process)