Method for absorbing nitrogen oxide tail gas and generating by-product p-phenylenediamine by using aniline

Abstract

The invention discloses a method for absorbing nitrogen oxide tail gas and generating by-product p-phenylenediamine by using aniline. The method comprises the following steps of: reacting part aniline with NOx to obtain diazonium salt; reacting the diazonium salt with the non-reacted aniline to obtain 1,3-diphenyltriazene, wherein the reaction products contain less p-nitroaniline and o-nitroaniline; making the 1,3-diphenyltriazene in a rearrangement reactor generate the rearrangement reaction at 30 DEG C-120 DEG C to convert into p-aminoazobenzene, wherein 90% of the 1,3-diphenyltriazene is converted into the p-aminoazobenzene and the remaining 1,3-diphenyltriazene is converted into o-aminoazobenzene and few impurities after the rearrangement reaction; separating the low distillates from the rearranged materials; and carrying out the hydrogenation reaction: using Raney nickel as a catalyst, continuously inputting hydrogen gas and controlling the pressure and the temperature to be 0.2MPa-4MPa and 25 DEG C-150 DEG C respectively to synthesize the p-phenylenediamine. The method provided by the invention reduces the production cost of the p-phenylenediamine and also reduces environmental pollution. A DCS (distributed control system) computer control system is used so that the automation of the whole system is realized and meanwhile the production efficiency is high.

Description

technical field [0001] The invention is a chemical clean production technology, which belongs to the technical field of chemical industry. Background technique [0002] The raw materials in the existing production process of p-phenylenediamine are relatively expensive, resulting in high production cost of p-phenylenediamine. For nitric acid production enterprises, the tail gas emissions contain a large amount of nitrogen oxide gas, which pollutes the environment; enterprises need to invest a lot of financial resources to solve the problem of nitrogen oxide gas emissions. Contents of the invention [0003] The present invention aims at the deficiencies in the prior art and provides a method for using aniline to absorb nitrogen oxide tail gas by-product p-phenylenediamine. This method uses new raw materials aniline and nitrogen oxide gas to prepare p-phenylenediamine; The production cost of p-phenylenediamine; nitrogen oxide gas is the tail gas of nitric acid produced by th...

AI Technical Summary

Problems solved by technology

[0002] Raw materials are relatively expensive in the existing production process of p-phenylenediamine, resulting in higher production cost of p-phenylenediamine

For nitric acid production enterprises, the tail gas emissions contain a large amount of nitrogen oxide gas, which pollutes the environment; enterprises need to invest a lot of financial resources to solve the problem of nitrogen oxide gas emissions