Method for improving diphenol recovery during phenol hydroxylation product separating and refining process

Abstract

The invention discloses a method of using physical means to improve the fluidity of tar and separate and recover diphenol. During production process of using phenol hydroxylation to prepare catechol / hydroquinone, certain amount of tar are byproducts, so more diphenol product needs to be reserved to improve the fluidity of the tar due to demanding to keep the conveyability of the tar in distillation separation system. The method is characterized in that: inherent composition with high fluidity is recovered from the tar and is re-added into phenol hydroxylation reaction products solution, thereby greatly improving the content of the composition with high fluidity in the tar and meeting the purpose of improving the fluidity of the tar. Because the fluidity of the tar is improved substantively, more diphenol product does not need to be reserved, thereby improving the recovery rate of the diphenol product. The method of using physical means to improve the fluidity of tar and separate and recover diphenol has the advantages of no need to increase special equipment, simple operation process and obvious effect in lowering the content of the diphenol product in the tar and improving the recovery rate of the diphenol product.

Description

technical field [0001] The invention relates to a method for improving the recovery rate of hydroquinone in the separation and purification process of phenol hydroxylation to produce ortho / hydroquinone products. Background technique [0002] In the process of producing catechol and hydroquinone by phenol hydroxylation, while obtaining ortho / hydroquinone products, the generation of by-product tar is unavoidable. Tar is a mixture, mainly composed of hydroquinone, polyhydroxy diphenyl ether compounds and polyphenyl ether macromolecular compounds. In actual industrial production, due to the requirements of pipeline transmission, it is necessary to make the separated tar have a certain fluidity. The fluidity of tar is related to its composition. As the content of hydroquinone and polyhydroxydiphenyl ethers in tar decreases, its freezing point increases gradually, and finally loses fluidity and forms a coke-like solid. Therefore, in the process of separating the tar, in order to...

AI Technical Summary

Problems solved by technology

This method can distill the hydroquinone in the tar as much as possible, but the disadvantage is that the third component is introduced in the rectification system, which may affect the product purity of hydroquinone; in addition, the third component in the tar discharge needs to be considered The loss of components, and the cost increase factors caused by the process of adding separation equipment to recover the third component

[0005] Hydroquinone is a high value-added chemical intermediate, and too much residue of hydroquinone products in tar will lead to a decline in the economics of the production process