Method for preparing purified acid from waste-acid after benzene refinery

Abstract

A process for preparing high-purity acid from the used acid generated by preparing refined benzene includes such steps as adding the salting-out agent to said used acid, heating while adding extractant, stirring at constant temp, laying aside for layering, taking the lower layer (high-purity acid), neutralizing upper layer by alkali, and distilling while adding organic solvent to obtain regenerated extractant.

Description

1. Technical field [0001] The invention belongs to the technology of refining and recovering crude benzene washed with sulfuric acid in a coking plant. In particular, it relates to a method for preparing purified acid from coking refined benzene waste acid. 2. Background technology [0002] In the process of producing refined benzene by pickling method, a large amount of waste acid will be produced, which contains tar-like sulfonic acid, glycolic acid, acetoformaldehyde resin, naphthalene, anthracene, phenol, styrene, indene, thiophene, etc. The substance is a black liquid containing 40-60% sulfuric acid. There is no effective recovery and utilization method at present. It often directly enters the external drainage system, which not only causes serious water pollution, but also wastes precious sulfuric acid resources, which has become an environmental protection problem for many coking plants. [0003] In recent years, coking plants at home and abroad have done a lot of ...

AI Technical Summary

Problems solved by technology

[0007] Although the above studies have all made progress to varying degrees, the cost of purifying waste acid from benzene increases due to the use of admixtures or ANPA; or the use of NaOH to neutralize and generate sodium phenolate, and then use 30% sulfuric acid to decompose the phenate to obtain crude phenol , the process is complicated, the cost is high, and the recovery rate of sulfuric acid is low;