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

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%.