Method for extracting thiophen from coking crude benzol

Abstract

The invention discloses a method for extracting thiophene from coking crude benzene, which comprises the following steps: (1) the coking crude benzene is taken as a raw material, an entrainer A is added into the coking crude benzene for azeotropic distillation to make the benzene and the entrainer A form an azeotropic mixture, the azeotropic mixture is condensed, kept stand and separated to obtain an organic phase containing the benzene and a saturated solution of the benzene, and the organic phase containing the benzene is rectified under normal pressure to obtain finished pure benzene; and (2) a rectification residual liquid remained after the coking crude benzene and the entrainer A are subjected to azeotropic distillation is added with an entrainer B for azeotropic rectification, formed zeotropic mixtures of the entrainer A and the entrainer B are separated from the thiophene, methylbenzene and homologous compounds, and the remaining rectification residual liquid taking the thiophene and the methylbenzene as main constituents is further rectified to obtain finished thiophene and methylbenzene respectively. The azeotropic mixtures of the entrainer A and the entrainer B are condensed, kept stand and separated to obtain the entrainer A and the entrainer B respectively for recycling. The method extracts a medicine intermediate, namely thiophene with higher value from the coking crude benzene, ensures that the obtained pure benzene achieves the nitration grade quality standard, can be used for basic organic synthesis, enlarge the application field of the coking crude benzene, and has good economic benefit and social benefit.

Description

technical field [0001] The invention relates to a method for extracting thiophene from coking crude benzene, belonging to the technical field of heterocyclic aromatic hydrocarbons and aromatic hydrocarbons. Background technique [0002] Thiophene is an important organic intermediate, mainly used in the production of medicines, dyes, and resins. Currently, there are two methods for preparing thiophene: extraction and chemical synthesis. Due to the complex process, harsh operating conditions, unstable catalyst activity and other reasons, the chemical synthesis method is very difficult to form a large-scale production, so it is inconvenient to be applied industrially. [0003] Thiophene mainly exists in coking crude benzene produced by coking, and is an impurity of coking crude benzene. Due to its existence, the application field of coking crude benzene is limited. Extracting thiophene from coking crude benzene not only obtains an important organic intermediate - thiophene, bu...

AI Technical Summary

Problems solved by technology

The rectification separation method requires a special and efficient rectification tower, and it is difficult for ordinary enterprises to meet this requirement; the sulfuric acid pickling method has a simple process and easy operation. Most domestic enterprises use this method to produce thiophene, but this method has serious pollution and low yield. Low, low product purity, difficult post-processing, difficult to popularize and apply; and solvent extraction method has less investment, high yield, high product purity, suitable for large-scale production, but how to choose a suitable solvent suitable for industrial production is still in the process of groping stage

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