CN-117402070-B - Separation method of front-end distillation column in production process of RT pessary

CN117402070BCN 117402070 BCN117402070 BCN 117402070BCN-117402070-B

Abstract

The invention relates to the technical field of production of rubber antioxidant intermediates-RT pessaries, and particularly discloses a high-efficiency separation method of a front fraction tower in the production process of RT pessaries. According to the invention, the unique physical properties of the phenazine are utilized, aniline originally contained in a material system is adopted as a carry-out solvent, the phenazine doped in the RT sauce is carried out in an auxiliary manner by continuously introducing the phenazine into a heavy component system of a front-end distillation tower kettle, so that the sufficient separation of the RT sauce and the phenazine at the bottom of the tower is realized, and the RT sauce does not have sublimation characteristics, so that the content of the RT sauce at the top of the tower can be effectively reduced when the phenazine in the tower kettle material is removed, and the yield of a finished product of the RT sauce is improved.

Inventors

DING JUNWEI
YU WENLONG
LI LI

Assignees

青岛科技大学
青岛利伟科技服务有限公司

Dates

Publication Date: 20260505
Application Date: 20230908

Claims (4)

1. A separation method of a front-end distillation column in the production process of RT pessary takes materials entering the front-end distillation column in the production process of RT pessary as treatment objects, and is characterized by comprising the following steps: (1) The materials are preheated and continuously conveyed into a front fraction tower from the middle part of the front fraction tower, rectification and separation are carried out under the condition of reduced pressure, wherein the materials comprise, by mass, 10-30% of aniline, 0.5-2% of phenazine, 0.1-1% of azobenzene, 0.2-1% of tar and the balance of RT pessary; (2) Continuously introducing a preheated aniline material from a reboiler of a tower kettle of the front-end distillation tower or from the lower part of the tower, carrying out auxiliary stripping on phenazine at the lower part of the tower, wherein the introduced aniline material accounts for 5-30% of the mass of the material in the front-end distillation tower, and the aniline preheating temperature is 100-180 ℃; (3) Continuously separating feed by controlling the temperature of the top of a front-end distillation column, the temperature of a column bottom and the reflux ratio, extracting aniline, azobenzene and phenazine as light components from the top of the column, conveying the light components to an aniline column for recycling aniline, conveying column bottom liquid to a subsequent RT sauce finished product column for continuous separation and purification, controlling the temperature of the top of the front-end distillation column to be 110-160 ℃, controlling the temperature of the column bottom to be 270-295 ℃, controlling the reflux ratio to be 1-15, wherein the mass fraction of RT sauce in extracted liquid at the top of the front-end distillation column is less than 0.2%, the mass ratio of phenazine in extracted liquid at the column bottom is less than 0.1%, and the mass content of aniline is 0.1-0.2%.
2. The method for separating a front-end distillation column in a production process of RT base according to claim 1, wherein in the step (1), the overhead pressure is controlled to be 2-15KPa.
3. The method for separating a front-end distillation column in a production process of RT base according to claim 1, wherein the aniline is fresh aniline or aniline recovered from an aniline column.
4. The method for separating a front-end distillation column in the production process of RT pessaries according to claim 1, wherein after the liquid extracted from the bottom of the front-end distillation column enters a finished product column of RT pessaries, the RT pessaries and aniline are separated by a mode of side line extraction of RT pessaries or serial connection of simple distillation columns at the top of the finished product column, so that the finished product RT pessaries with high purity are obtained.

Description

Separation method of front-end distillation column in production process of RT pessary Technical Field The invention relates to the technical field of production of a rubber antioxidant intermediate 4-aminodiphenylamine (RT-pemetrexed), in particular to a separation method of a front-end distillation column in the production process of RT-pemetrexed. Background 4-Aminodiphenylamine is commonly called RT-pessary, and is a key intermediate for synthesizing p-phenylenediamine rubber antioxidant. The nitrobenzene method is a main industrial production method of the current RT-sauce, the reaction path of the method is to take aniline and nitrobenzene as raw materials, carry out condensation reaction in the presence of an alkaline condensation catalyst to generate condensation liquid containing p-nitrodiphenylamine and p-nitrosodiphenylamine, and then prepare hydrogenation feed liquid containing the product RT-sauce through catalytic hydrogenation reaction. During the condensation reaction, aniline is added in excess, and a series of byproducts such as phenazine, azobenzene, tar and the like are inevitably generated during the reaction, wherein the phenazine is used in a majority. Therefore, the feed liquid after hydrogenation reaction contains excessive aniline, phenazine, azobenzene, tar and other byproducts besides the product RT-sauce, and after separation and recovery of the condensation catalyst, the feed liquid needs to be purified by a subsequent refining process to obtain a high-purity RT-sauce finished product. The rectification separation is a main refining method in the industrial production of the RT-pemetrexed. At present, a continuous rectification operation mode with two or three towers connected in series is generally adopted. The raw material liquid of RT-sauce containing impurities such as aniline, phenazine, azobenzene, tar and the like firstly enters a first tower, also called a front-end distillation tower or a light component tower or a phenazine tower, after rectifying and separating in the tower, aniline, azobenzene and most of phenazine are extracted from the tower top, and heavy component impurities such as RT-sauce, a small amount of phenazine, tar and the like enter a second tower (also called a finished product tower) for continuous separating and refining. And (3) extracting RT-sauce from the top of the finished product tower, and enriching heavy components such as tar and the like in the tower bottom. The phenazine is used as a main byproduct in the production process of the RT-pemetrexed, the production amount is large, the boiling point of the phenazine is close to that of the RT-pemetrexed, and the separation difficulty of the conventional rectification method is large, so that in the prior art method, the produced liquid at the top of the front-end distillation tower often contains more RT-pemetrexed, and the tower bottom liquid is also doped with more phenazine. The method not only reduces the finished product yield of the finished product tower RT-sauce, but also greatly increases the separation difficulty of the finished product tower. Not only increases the separation energy consumption, but also reduces the final yield of the product. In addition, because of the difficulty in separation, the phenazine carried into the final product tower tends to be mixed in the final product RT-sauce, directly affecting the product quality of the downstream p-phenylenediamine rubber antioxidant. Therefore, the simple, convenient, efficient and advanced separation technology of the front-end distillation column is developed to realize the efficient separation of the RT-pemetrexed and the phenazine, and has important significance for the high-quality and efficient production of the RT-pemetrexed. Disclosure of Invention The invention provides a separation method of a front-end distillation column in the production process of RT pessaries, which is efficient, convenient and low in treatment cost, in order to make up the defects of the prior art. The invention is realized by the following technical scheme: a separation method of a front-end distillation column in the production process of RT pessary takes materials entering the front-end distillation column in the production process of RT pessary as treatment objects, and specifically comprises the following steps: (1) The material is preheated and then continuously conveyed into the front fraction tower from the middle part of the front fraction tower, and is subjected to rectification separation under the condition of reduced pressure; (2) Continuously introducing a preheated aniline material from a reboiler of a tower bottom or the lower part of the front-end distillation tower, and carrying out auxiliary stripping and taking out phenazine at the lower part of the tower; (3) And controlling the temperature and reflux ratio of the top and the bottom of the front fraction tower, continuously separating the feed, extracting aniline, azobenzen