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Efficient absorption method for 2-cyanopyridine

A technology of cyanopyridine and picoline ammonia, which is applied in the field of 2-cyanopyridine synthesis, can solve the problems of small contact area and insufficient contact of reaction gas, and achieve uniform spatial distribution, small particle diameter and dense spatial distribution Effect

Inactive Publication Date: 2015-02-18
HIGH & NEW TECH RES CENT OF HENAN ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In the relevant literature and industrial production of picoline ammoxidation to produce cyanopyridine, after the completion of ammoxidation, in order to obtain cyanopyridine in the reaction gas, the absorption Most of the solvents are water or organic solvents, and the absorption equipment used is a packed tower or a plate tower, but the contact area between the reaction gas and the absorbent in the device is small, and the contact with the reaction gas is not sufficient. In order to control the amount of absorbent (water), it contains Absorbents for cyanopyridine and ammonia need to be in contact with high-temperature gas for a long time to ensure complete absorption and make the cyanopyridine in the absorption liquid reach a certain content, which will result in partial hydrolysis of cyanopyridine

Method used

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  • Efficient absorption method for 2-cyanopyridine

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Comparison scheme
Effect test

Embodiment 1

[0023] like figure 1 As shown, the reaction mixture gas produced by the ammonia oxidation in the ammonia oxidation reactor 1 is initially cooled to 200-230 °C by the heat exchanger 2, and then enters the absorption tower 3, and is sprayed with the high-pressure fine water mist nozzle 3-1. The high-pressure fine water mist out is subjected to heat exchange and material exchange, and the condensed product sinks into the bottom of the absorption tower 3, is sent to the follow-up 2-cyanopyridine separation and purification system after being cooled by the cooler 3-2; The condensed gas enters the tubular cooler 4 from the top of the absorption tower 3 for cooling, and the cooled liquid phase enters the storage tank 5, and after being merged with the water inlet pipeline 7, it is pressurized by the high-pressure water mist pump 6 and sent to the high-pressure fine mist pump. Water mist nozzle 3-1; non-condensable gas is discharged from the top of the storage tank 5 and enters the t...

Embodiment 2

[0027] A 2-cyanopyridine high-efficiency absorption method: in the process of preparing 2-cyanopyridine by ammoxidation of 2-picoline, high-pressure fine water mist is used as an absorbent, and the temperature obtained after the ammoxidation reaction and preliminary cooling is The mixed gas at 205-210°C is cooled and absorbed; the particle size of the high-pressure fine water mist is less than 50 μm. The high-pressure fine water mist is sprayed from the high-pressure fine water mist nozzle located at the top of the absorption tower, and the 2-cyanopyridine aqueous solution obtained at the bottom of the tower stays in the absorption tower for no more than 0.5 h. Then, it is pumped to Subsequent separation and purification are carried out in the rectification tower. The water used in the high-pressure water mist is pure water, which is used once and does not circulate directly. details as follows:

[0028] The preheated 2-picoline (flow rate 10.0 kg / h), ammonia, air and other ...

Embodiment 3

[0030] A 2-cyanopyridine high-efficiency absorption method: in the process of preparing 2-cyanopyridine by ammoxidation of 2-picoline, high-pressure fine water mist is used as an absorbent, and the temperature obtained after the ammoxidation reaction and preliminary cooling is The mixed gas at 218-225°C is cooled and absorbed; the particle size of the high-pressure fine water mist is less than 50 μm. The high-pressure fine water mist is sprayed from the high-pressure fine water mist nozzle located at the top of the absorption tower, and the 2-cyanopyridine aqueous solution obtained at the bottom of the tower stays in the absorption tower for no more than 0.5 h. Then, it is pumped to Subsequent separation and purification are carried out in the rectification tower. The water used in the high-pressure water mist is pure water, which is used once and does not circulate directly. details as follows:

[0031] The preheated 2-picoline (flow rate: 9.5 kg / h) and air mixed gas enters...

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Abstract

The invention relates to an efficient absorption method for 2-cyanopyridine. The method comprises the following concrete steps: in a process of preparing 2-cyanopyridine by ammoxidation of 2-methylpyridine, cooling and absorbing mixed gas with the temperature of 200-230 DEG C, obtained through primary cooling after ammoxidation reaction by taking high-pressure fine water mist as an absorbent, wherein the particle size of the high-pressure fine water mist is not more than 100 microns (preferably less than 50 microns). According to the method, the mixed gas generated by ammoxidation during production of 2-methylpyridine is quickly cooled and absorbed by the high-pressure fine water mist with the particle size of not more than 100 microns, so that the hydrolysis of 2-cyanopyridine is inhibited and the absorption efficiency is improved.

Description

[0001] technical field [0002] The invention belongs to the technical field of 2-cyanopyridine synthesis, and in particular relates to a high-efficiency absorption method for 2-cyanopyridine, which is suitable for the ammoxidation reaction in the process of preparing 2-cyanopyridine from 2-picoline through ammoxidation. Absorption of 2-cyanopyridine in the mixed gas after the end. Background technique [0003] Cyanopyridines include 2-cyanopyridine, 3-cyanopyridine, and 4-cyanopyridine, which are important pesticide and pharmaceutical intermediates. Regarding the synthesis of cyanopyridine, the catalytic ammoxidation method of picoline is mainly used at present. The mixed gas after the ammoxidation reaction includes cyanopyridine, ammonia, carbon dioxide, picoline, pyridine, pyridine amide, etc., and its temperature is at 300-450°C. Usually, the reaction gas after the ammoxidation is completed is cooled and absorbed by an organic solvent or water, and then further separate...

Claims

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Application Information

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IPC IPC(8): C07D213/84
CPCC07D213/84
Inventor 王利敏程森祥陈彤王强李玉江
Owner HIGH & NEW TECH RES CENT OF HENAN ACAD OF SCI
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