Application of NMP in petrochemical processes

NMP is a nitrogen-containing 5-membered ring compound. It has the following excellent characteristics:

—Highly polar, miscible with most organic solvents.

—It is mixed with water in various proportions.

—Compared with similar solvents, its flash point is high.

—High boiling point, low freezing point, easy to handle.

—Chemically and thermally stable, and non-corrosive.

Application: Due to its affinity for unsaturated hydrocarbons and aromatic hydrocarbons, NMP is used as an extraction medium in many industrial processes, especially in applications in petrochemical processes, such as butadiene recovery, BTX extraction, and lubricant oil purification.

1.Butadiene recovery:
As early as half a century ago, West Germany used N-methylpyrrolidone (NMP) as a solvent to crack, extract and distill butadiene. Later, it was gradually adopted and improved all over the world. The NMP extraction and distillation process of butadiene has high solvent selectivity, non-toxicity, non-corrosion, high hydrolytic and thermal stability, high boiling point, low main vapor pressure at normal temperature, high butadiene yield and high purity. And the overall technical and economic effects of the entire process are superior.

Using a mixed solvent of NMP and salt solution, the main operating parameters can be much smaller than those of the existing technology, greatly reducing equipment costs and operating costs. And the purity of butadiene in the product can reach more than 99.5%, and the recovery rate can reach more than 98.5%.

2.BTX extraction:
BTX has a wide range of uses. It is a basic organic chemical raw material in the petrochemical industry. It can be used to produce a variety of chemical products such as synthetic rubber, synthetic fibers and synthetic resins. It can also be used to produce a variety of fine chemical products. It can also be used as high-octane gasoline. The blending ingredient accounts for about 21% of the gasoline composition.

Traditional BTX production uses catalytic reformed oil and pyrolysis gasoline as the main raw materials. However, due to the lack of petroleum resources, the prices of these chemicals remain high. Some new process routes have been developed, such as when used as aromatic hydrocarbon extraction agent due to NMP. It has high solubility and low vapor pressure for aromatic hydrocarbons, low extraction agent loss rate and high aromatic hydrocarbon recovery rate during the process.

3.Lubricating oil purification:
In order to realize the lubricating oil refining process, the solvent should have appropriate selectivity and – certain solvency capacity, different selectivity solvent, because of its own molecular structure is different, solvency capacity and selectivity is also different.

NMP its own molecular structure is different, solubility and selectivity are different, excellent selectivity, toxicity is very small solvent, and the solvent refining process has excellent selectivity, toxicity is very small solvent, and the solvent refining process has good product quality, high yield and so on, in the lubricant solvent refining in the greater superiority. At present, the proportion of NMP refining process in lubricant solvent refining in the world has been more than 50%, which shows that NMP refining process has great development potential.