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Method for replacing phosgene synthetic tower catalyst

一种合成塔、催化剂的技术，应用在光气合成塔催化剂更换领域，能够解决安全风险大、消耗大氮气、吹扫速度慢等问题，达到操作安全、提高工艺安全性、缩短光气脱除时间的效果

Active Publication Date: 2016-08-03
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] In the prior art, pure nitrogen is used to directly purge phosgene for synthesis. In the case of low phosgene concentration in the later stage of purging, a large amount of nitrogen needs to be consumed, and the purge speed is very slow, and some phosgene remains in the synthesis tower. Replace the synthesis tower catalyst high security risk

Method used

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  • Method for replacing phosgene synthetic tower catalyst
  • Method for replacing phosgene synthetic tower catalyst

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] After the phosgene synthesis tower stops feeding, feed 100Nm from the bottom of the synthesis tower 3 The nitrogen of / h, nitrogen temperature is 100 ℃, and moisture content in nitrogen is 100ppm, and nitrogen pressure is 0.15MPa, and nitrogen continues to pass into 2 days, and the phosgene concentration of outlet of phosgene synthesis tower after measuring purging is 0.45% (v / v ). Then pass through the ammonia gas for purging, first pass through the ammonia gas to suppress the pressure, hold the pressure of the phosgene synthesis tower to 1MPa, hold the pressure for 2 hours, then open the outlet of the phosgene synthesis tower, and repeat the pressure suppression 8 times. Then continue to feed ammonia gas, the flow rate of ammonia gas is 80Nm 3 / h, the ammonia temperature is 40°C, the moisture content in the ammonia is 50ppm, the ammonia is purged for 5 days, and the phosgene concentration at the outlet of the phosgene synthesis tower is measured to be 0.5ppm. After ...

Embodiment 2

[0044] After the phosgene synthesis tower stops feeding, feed 200Nm from the bottom of the synthesis tower 3 The nitrogen of / h, the nitrogen temperature is 120 ℃, and the moisture content in the nitrogen is 300ppm, and the nitrogen pressure is 0.2MPa, and the nitrogen continues to feed for 3 days, and the phosgene concentration at the outlet of the phosgene synthesis tower after measuring and purging is 0.3% (v / v ). Ammonia gas is introduced first to suppress the pressure, the pressure of the phosgene synthesis tower is suppressed to 2 MPa, and the pressure is suppressed for 4 hours, then the outlet of the phosgene synthesis tower is opened, and the pressure is repeatedly suppressed 4 times. Then continue to pass into the ammonia purging, the ammonia flow rate is 100Nm 3 / h, the ammonia temperature was 60°C, and the ammonia gas was purged for 3 days, and the phosgene concentration at the outlet of the phosgene synthesis tower was measured to be 0.4ppm. After purging, the ph...

Embodiment 3

[0046] After the phosgene synthesis tower stops feeding, feed 400Nm from the bottom of the synthesis tower 3 The nitrogen of / h, the nitrogen temperature is 150 ℃, and the moisture content in the nitrogen is 200ppm, and the nitrogen pressure is 0.25MPa, and the nitrogen continues to feed for 6 days, and the phosgene concentration at the outlet of the phosgene synthesis tower after measuring and purging is 0.1% (v / v ). Then feed ammonia gas for purging, first feed ammonia gas to suppress the pressure, suppress the pressure of the phosgene synthesis tower to 3Mpa, hold the pressure for 5h, then open the outlet of the phosgene synthesis tower, and repeatedly suppress the pressure 5 times. Then continue to pass into the ammonia purging, the ammonia flow rate is 150Nm 3 / h, the ammonia temperature is 80°C, the ammonia gas is purged for 1 day, and the phosgene concentration at the outlet of the phosgene synthesis tower is measured to be 0.2ppm. After purging, the phosgene enters t...

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Abstract

The invention discloses a method for rapidly removing phosgene in a catalyst when a phosgene synthetic tower catalyst is replaced. The method is characterized in that a nitrogen purging method is employed for purging phosgene which is absorbed in phosgene synthetic tower catalyst active carbon and is easily desorbed, ammonia gas is used for purging, then ammonia gas and phosgene which is difficultly desorbed in the phosgene synthetic tower catalyst are subjected to a reaction for removal, a water gun is used for flushing a phosgene synthetic tower, and then the phosgene synthetic tower is dried by hot gas. The phosgene content at an outlet of the phosgene synthetic tower after purging is carried out is lower than 0.5 ppm, phosgene purging time by the phosgene synthetic tower is obviously reduced, nitrogen consumption amount is greatly reduced, and operation security is increased.

Description

technical field [0001] The invention relates to a method for replacing a catalyst in a phosgene synthesis tower, in particular to a method for rapidly removing phosgene in a catalyst when the catalyst of a phosgene synthesis tower is replaced. technical background [0002] Phosgene is an important organic intermediate, which has many uses in pesticides, medicine, engineering plastics, polyurethane materials and military affairs. There are many ways to prepare phosgene. At present, the main method for industrialized production of phosgene is to use carbon monoxide and chlorine as raw materials, and use activated carbon as a catalyst to synthesize phosgene. The commonly used activated carbon is coconut shell carbon and coal-based carbon. At present, 80% of the phosgene produced in industry is used for the production of isocyanate, mainly for the production of MDI (diphenylmethane diisocyanate), TDI (toluene diisocyanate) and polycarbonate. The production of isocyanate has ver...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J8/06B01J19/14C01B31/28
CPCB01J8/0278B01J8/0292C07C273/02B01J8/06C01B32/80B01J8/008B01J27/20B01J2208/06
Inventor 张宏科姚雨赵东科曹官义刘小高曹友念李翀马亚波
Owner WANHUA CHEM GRP CO LTD
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