Method for recovering phosgene in continuous production process of toluene di-isocyanate

A technology of toluene diisocyanate and production process, which is applied in the field of phosgene recovery in the continuous preparation process of toluene diisocyanate, can solve the problems of high risk, high cost of phosgene recovery process, poor operation stability, etc., and achieve low cost and reduced Operation and maintenance costs, the effect of reducing investment

Active Publication Date: 2010-03-17
SEDIN ENG +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to the high excess rate of phosgene, resulting in a large flow of gas rich in phosgene, coupled with the complexity of the phosgenation reaction system and the high toxicity of phosgene itself, the

Method used

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  • Method for recovering phosgene in continuous production process of toluene di-isocyanate
  • Method for recovering phosgene in continuous production process of toluene di-isocyanate
  • Method for recovering phosgene in continuous production process of toluene di-isocyanate

Examples

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Embodiment 1

[0030] This example relates to the recovery of phosgene during the continuous preparation of toluene diisocyanate (TDI) by liquid-phase phosgenation of toluene diamine in o-dichlorobenzene (ODCB). The percentage composition in each stream refers to the mass percentage.

[0031] The first phosgene absorption tower is a packed tower with 10 theoretical plates. Gas stream a rich in phosgene, hydrogen chloride and a small amount of impurities (from the degassing tower and the hydrogen chloride stripping tower in the production process of toluene diisocyanate, the temperature is 5 ℃, the absolute pressure is 120kPa, and its mass flow rate is 5000kg / hr, Containing 81.9% phosgene, 17.4% hydrogen chloride, 0.6% carbon tetrachloride and a small amount of ODCB and carbon dioxide) enter from the bottom of the first phosgene absorption tower; -10 ℃, ODCB with an absolute pressure of 110kPa enters from the top of the tower at 20000kg / hr Enter;

[0032] The first phosgene absorption tower...

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Abstract

The invention discloses a method for recovering phosgene in continuous production process of toluene di-isocyanate, comprising the following steps: importing a gas stream with an absolute pressure of0.08-0.2 MPa, which is generated in a preparation process of the toluene di-isocyanate, into the bottom of a first phosgene absorption tower and leading inert organic solvent into the first phosgene absorption tower to absorb; leading part of tower bottom absorption liquid in the first phosgene absorption tower into a second phosgene absorption tower after being boosted by a tower bottom liquid pump; importing another gas stream with the absolute pressure of 0.5-0.8 MPa, which is generated in the preparation process of the toluene di-isocyanate, into the second phosgene absorption tower, and continuing absorbing through adding the inert organic solvent from the top of the second phosgene absorption tower; and reusing the phosgene inert solvent solution acquired from the bottom of the second phosgene absorption tower in the continuous production process of the toluene di-isocyanate. The method avoids using large-sized compressors, reduces the cost on operation and maintenance and achieves the purpose for recovering the phosgene at lower cost.

Description

technical field [0001] The invention relates to a method for recovering phosgene in the continuous preparation process of toluene diisocyanate. Background technique [0002] Polyurethane materials have the characteristics of convenient modification, easy processing and molding, and simple construction. They are widely used in various fields such as heat insulation, shockproof, sound insulation, cushion materials, packaging and light structures. Isocyanate is an important monomer raw material in the polyurethane industry. The method of preparing isocyanate by phosgenation of primary amine has been reported many times in patents, and has been applied on a large scale in industry, especially aromatic isocyanate TDI (toluene diisocyanate), The reactions that may occur during its preparation are as follows: [0003] [0004] [0005] TDI+urea→TDI biuret (7) [0006] TDI+TDI biuret → polyurea (8) [0007] Reaction (1), (2) is the main reaction to generate isocyanate, and ...

Claims

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Application Information

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IPC IPC(8): C07C265/14C07C263/10C01B7/01
Inventor 闫少伟李韡潘国平张金利杨在建徐双庆郭可宇辛峰韩优杨锦
Owner SEDIN ENG
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