Treatment method of residues from nitrotoluene rectification kettle

Abstract

The invention discloses a treatment method of residues from a nitrotoluene rectification kettle. The method comprises the following steps: performing a hydrogenation reduction reaction on the residues from the rectification kettle and hydrogen in the presence of a catalyst, thereby generating methylaniline comprising three isomers, namely, o-toluidine, m-toluidine and p-toluidine, from the mononitrotoluene in the kettle residues and generating diaminotoluene comprising two isomerides, namely, 2,4-diaminotoluene and 2,6-diaminotoluene, from the dinitrotoluene in the kettle residues; and then performing rectification separation, thereby obtaining a methylaniline finished-product and a diaminotoluene finished-product. The method is simple in process, short in procedure, clean and environment-friendly, and realizes the rational utilization of waste resources, i.e., the products with high additional values are produced by utilizing low-value resources, thereby bringing economic benefits to enterprises. As a result, the recycling of waste materials, the energy conservation and the emission reduction are realized.

Description

technical field [0001] The invention belongs to the technical field of solid waste treatment produced in the chemical production process, and in particular relates to a treatment method for mononitrotoluene (MNT) rectification still residue. Background technique [0002] Mononitrotoluene is an important fine chemical raw material and intermediate. Its three isomers, ortho, meta, and para, are widely used in the production of dyes, medicines, pesticides, and plastic additives. [0003] Mononitrotoluene is mainly produced by nitrating toluene with mixed acid. The nitration reaction of toluene is affected by many factors. A certain amount of nitrophenols and dinitrotoluene (DNT) will be generated during the nitration reaction. Phenols are discharged with waste water in the neutralization and dephenolization process, and dinitrotoluene is discharged with the still residue in the rectification process. Based on the consideration of safety and product quality, when the mass fract...

AI Technical Summary

Problems solved by technology

The disadvantages of this treatment method are: (1) The steam distillation process will generate waste water, which will increase the treatment and discharge of waste water, which is not environmentally friendly; (2) The treatment process is long and complicated, requiring many equipment and high energy consumption. Increase production cost; (3) use methanol to purify dinitrotoluene, only get 2,4-dinitrotoluene finished product, 2,6-dinitrotoluene is not recovered, waste of resources

[0006] Since the main component of the distillation residue of mononitrotoluene is nitro substances, it is difficult to degrade. Therefore, at present, the residue is generally incinerated as solid waste in China, and the cost of incineration per ton of residue is as high as 3000- 4,000 yuan, not only increases the burden on mononitrotoluene production enterprises, but also causes secondary pollution to the environment, which is not conducive to environmental protection