Method for preparing thiophene through variable pressure azeotropic distillation

Abstract

The invention discloses a method for preparing thiophene through variable pressure azeotropic distillation. The method is carried out in a first distilling tower and a second distilling tower which are serially connected with each other, and comprises the following steps of (1) mixing crude thiophene extracted from coked crude benzene and an entrainer according to a weight ratio of 60-65: 35-40 to obtain an azeotrope; entering the first distilling tower firstly; distilling at a pressure of 0.08-0.12Mpa, obtaining a first azeotrope on the top of the tower at the temperature 65 to 75 DEC G according to the weight ratio of the thiophene to the entrainer of 65-68 : 32-35; and (2) sending the first azeotrope into the second distilling tower, distilling at a pressure of 0.4-0.5Mpa, and obtaining the finished product of thiophene at the bottom of the distilling tower at the temperature of 130 to 140 DEC G. The crude thiophene extracted from the coked crude benzene is effectively utilized; the economic benefit is good; the process flow is simple; pollution to environment is low; and a product with high purity can be obtained.

Description

technical field [0001] The invention relates to the technical field of distillation and purification, in particular to a method for preparing high-purity thiophene by using low-content thiophene extracted from coking crude benzene as a raw material by pressure swing azeotropic distillation. Background technique [0002] Thiophene is a colorless, foul-smelling, tear-inducing liquid. Thiophene is naturally present in petroleum, and its content is as high as several percent. It is mainly used in the denaturation of ethyl alcohols in industry and can also be used as a solvent. Thiophene can replace benzene as a raw material for producing dyes and plastics in many occasions, but because thiophene is relatively active, it is generally not as good as products made from benzene. New uses of thiophene heterocyclic compounds are constantly being developed. Bell Labs found that thiophene can be polymerized into a plastic with superconducting properties, and the cost is low. It is expe...

AI Technical Summary

Problems solved by technology

At present, the rectification and extraction methods in the world are mainly hydrorefining and sulfuric acid refining. The hydrorefining method can obtain high-quality benzene, but the process technology is complicated, the operating conditions are harsh, the equipment investment is large, and the processing cost is high, so it is difficult to obtain small-scale Popularization and application; the sulfuric acid method has serious pollution, low yield, and difficult post-treatment. Although the process is relatively mature, the purification depth is not enough. This method has been banned in many developed countries; in addition, there are solvent extraction and freeze crystallization methods , but it is difficult to obtain high-purity products

In many chemical syntheses using benzene as a solvent, the product quality is seriously affected due to the presence of trace amounts of thiophene, and even scrapped

[0004] Therefore, the refining of coking benzene and the recovery of thiophene have always been a technical problem. In the hydrofining method and sulfuric acid refining method, thiophene is decomposed and destroyed during the refining process, and finally discharged into the environment. This not only wastes limited resources, but also also caused serious pollution to the environment

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