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Method for absorbing and utilizing phosgene tail gas

A tail gas absorption and phosgene technology, applied in chemical instruments and methods, preparation of organic compounds, carboxylate preparation, etc., can solve the problems of unrealized industrial utilization value, environmental pollution, large liquid alkali, etc., and achieve easy operation, The effect of less investment and low energy consumption

Active Publication Date: 2013-01-02
JIANGSU KUAIDA AGROCHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above absorption methods not only produce a large amount of waste acid, but also consume a large amount of liquid caustic soda, causing a lot of environmental pollution
[0003] According to the data, there are also individual enterprises that use the cryogenic method to recover phosgene tail gas, but because the recovered phosgene contains a large amount of hydrogen chloride and other gas impurities, the industrial utilization value cannot be realized.

Method used

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  • Method for absorbing and utilizing phosgene tail gas
  • Method for absorbing and utilizing phosgene tail gas
  • Method for absorbing and utilizing phosgene tail gas

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Take a 500ml four-neck flask and add 250g of dichloroethane, plug the bottle stopper, weigh 548g, cool the material to -5°C to 0°C, and feed the phosgene tail gas in the production process of Diuron (the phosgene content is about 37% (V / V), hydrogen chloride 43%, carbon monoxide 20%), 400~500mg / min per minute, and the unabsorbed tail gas is absorbed and treated with 5% alkali. After 3 hours, the absorption was stopped, and 735g of the material bottle was weighed, and the weight of the solution increased by 187g, wherein the phosgene content was 29.5%, and the hydrogen chloride was 15.3%.

Embodiment 2

[0029] Take a 500ml four-neck flask and add 250g of chlorobenzene, stopper the bottle, weigh 539g, cool the material to -5°C to 0°C, and feed the phosgene tail gas in the production process of chloromelon, (the phosgene content is about 38 % (V / V), hydrogen chloride 42%, carbon monoxide 20%), 400-500 mg / min is introduced per minute, and the unabsorbed tail gas is absorbed and treated with 5% alkali. Absorption was stopped after 3 hours, 728g of the material bottle was weighed, and the weight of the solution increased by 189g, wherein the content of phosgene was 30.2%, and the content of hydrogen chloride was 11.3%.

Embodiment 3

[0031] In the four-necked flask of 500ml, add dichloroethane 100ml, promotor M 50g, composite catalyst 2g (bipyridine 1.8g, Yb(OTf) 3 and 0.2g, the sodium trifluoromethanesulfonate of ytterbium), be warming up to 70 ℃~75 ℃, add dropwise the phosgene dichloroethane solution 110g that absorbs in example 1, keep reaction temperature 70 ℃~75 ℃, tail gas water After absorption, use alkali to absorb, add dropwise for 5 hours, and keep warm for 1 hour to remove the dichloroethane solvent. The crude product is vacuum (0.7mmHg) distilled to obtain 2-chlorobenzene Thiazole 48.2g, content 99.1%, yield 95%.

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Abstract

The invention discloses a method for absorbing and utilizing phosgene tail gas. The method comprises the following steps: the phosgene tail gas generated in a phosgenation process (especially the phosgene tail gas generated in the phosgenation process with content of between 10 and 50 percent (V / V), such as the phosgene tail gas generated in the phosgenation process of diuron, chlortoluron and other products) is directly cooled and absorbed through a halohydrocarbon solvent, phosgene and partial hydrogen chloride in the phosgene tail gas are recovered to obtain a phosgene tail gas solution; the phosgene tail gas solution is used as a phosgene raw material for synthesizing pesticide intermediate or acyl chloride chemical products in the action of a composite catalyst; and the composite catalyst contains at least one pyridine or bipyridyl and Lewis acid salt of at least one rare-earth metal. Compared with other methods, the solvent cooling direct absorption method has the advantages of less investment, low energy consumption, convenience in operation and the like.

Description

technical field [0001] The invention relates to a method for absorbing and utilizing phosgene tail gas. Background technique [0002] Phosgene is an important raw material for chemical production, with a domestic production capacity of 1.5 million tons (the statistical production capacity in 2008 was 1.16 million tons). It is widely used in industrial production such as pesticides, medicines, fuels, and polyurethane. attention. In the chemical production process using phosgene as raw material, phosgene tail gas containing phosgene will be produced. Due to the different requirements of process control in the production process, the content of phosgene tail gas produced is also different, generally between 10% and 50% (V / V). At present, in terms of absorption and utilization of phosgene tail gas in China, except for the production of TDI and MDI polyurethane industries, which have invested heavily in toluene absorption and thermal desorption method to recover phosgene, othe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D53/14C01B31/28C07D277/68C07C53/42C07C51/60C01B32/80
Inventor 韩邦友施永平钱圣利
Owner JIANGSU KUAIDA AGROCHEM
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