Method extracting high purity n-hexane by integrating rectification and extraction

Abstract

The invention relates to a method extracting high purity n-hexane by integrating rectification and extraction. The method utilizes aromatic hydrocarbon raffinate oil as a raw material and adopts a three-tower technological process which combines continuous rectification and extractive distillation. Firstly, distillate lighter than n-hexane is removed in a rectifying tower, and n-hexane distillate which is around 80% in content is obtained at the bottom of the tower. The distillate at the bottom of the tower is adopted as the raw material of an extractive distillation tower, N-methyl pyrrolidone is adopted as an extracting solvent to be delivered into the extractive distillation tower, and the proportion of the N-methyl pyrrolidone and raw oil is 8:1, after extractive distillation, high purity n-hexane is extracted at the top of the tower by integrating rectification and extraction, and heavy components which are rich in methylcyclopentane and the extracting solvent are at the bottom of the tower. Materials at the bottom of the tower are delivered into a solvent recovery tower, distillate oil which is rich in methylcyclopentane is separated at the top of the tower, and N-methyl pyrrolidone solvent is at the bottom of the tower and sent back to the extractive distillation tower to be recycled. By means of the method, n-hexane content can achieve 99%, no extracting solvent is contained in products, solvent consumption is smaller than 0.1%, one-off yield of n-hexane is larger than 95%, and compared with traditional rectification, energy consumption can be saved over 50%.

Description

technical field [0001] The invention relates to a chemical solvent preparation, more specifically, it is mainly used as a solvent for olefin polymerization catalysts, an extraction solvent for edible vegetable oil, a solvent for drug extraction, a solvent for rubber and paint, and a diluent for pigments. Background technique [0002] The application of hexane solvent in different industries has different requirements for the content of n-hexane. For example, the extraction solvent of edible vegetable oil can meet the requirements if the hexane content reaches more than 60%. However, the hexane solvent used in chemical process polymerization requires a hexane content of more than 99% (such as the hexane solvent used in chemical polymerization of China Sea Shell ethylene plant). At present, the n-hexane solvent with a purity of 99% used in China is imported from abroad, and the price is high. At present, the domestic import volume is about 10,000 tons, and the main market is...

AI Technical Summary

Problems solved by technology

Since the boiling points of n-hexane and methylcyclopentane are close, if the conventional rectification method is used, not only the energy consumption is large, but the separation accuracy cannot meet the requirements, and it is difficult to obtain more than 99% n-hexane

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