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Method for recovering toluene diamine from high boiling tar residue discharged from toluene diisocyanate preparation process

A technology for toluene diisocyanate and toluene diamine, which is applied in the field of recovering toluene diamine from high-boiling tar residues discharged from the preparation process of toluene diisocyanate, can solve problems such as high operating costs, large processing facilities, and prolonged process time.

Active Publication Date: 2006-07-12
HANWHA CHEMICAL CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the disadvantages of the incineration method in terms of economy are: the incinerator usually operates at a temperature of 1000 ° C or higher, which requires high operating costs. In addition, due to the high-temperature combustion process, secondary pollutants, including nitrogen oxides (NO x ), sulfur oxides (SO x ), dioxins, etc., and other equipment is required to remove them
However, the problem with this method is that the solid waste is in the hydrolysis medium under low or medium pressure conditions, because it is limited by mass transfer characteristics such as permeation, diffusion speed, etc., so not only the process time is prolonged, but also requires more large processing facility
[0013] As mentioned above, the conventional methods for recovering toluene diamine from the tar generated during the production of toluene diisocyanate have problems including: poor reactivity due to mass transfer resistance at 250°C or lower; Catalysts to generate salts; Excessive water usage; Nitrogen content in waste water or discarded materials causing secondary pollution; Prolonged reaction time; Toluenediamine pyrolyzes at 400°C or higher
The cost of the traditional method is also high. The reason is that the tar residue is hydrolyzed because the free toluene diisocyanate contained in the tar residue is not sufficiently extracted to maintain the flow state of the residue, and a part of the toluene diisocyanate prepared in the process can be converted Toluenediamine

Method used

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  • Method for recovering toluene diamine from high boiling tar residue discharged from toluene diisocyanate preparation process
  • Method for recovering toluene diamine from high boiling tar residue discharged from toluene diisocyanate preparation process

Examples

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Effect test

Embodiment approach 1

[0048] and figure 1 As in the illustrated embodiment, the slurry is pressurized with a high pressure pump 121 and then heat exchanged in a heat exchanger 122 with the hydrolyzed slurry from the previous hydrolysis process in a reactor 124, followed by a heat exchange in a heater 123. Additional heating is applied followed by hydrolysis treatment in reactor 124. Hydrolysis reactor 124 adopts with figure 1 The same operating conditions as in reactor 24.

[0049] figure 2 The illustrated embodiment features oxidative removal of contaminants from the first overhead fraction while recycling spent catalyst and waste water discharged from the toluenediamine recovery process.

[0050] like figure 2 As shown, the hydrolyzed slurry flows through the heat exchanger 122 and the pressure reducing valve 125, and then enters the distillation column 131, during which the slurry cools down in the heat exchanger 122, and the pressure is reduced through the pressure reducing valve 125. In...

Embodiment 1

[0069] The same equipment and high-boiling tar residue as in Comparative Example 1 were used. 200 g of the solid residue was dispersed in 600 g of a 5% by weight aqueous solution of sodium carbonate, and then a hydrolysis reaction was performed at 300° C. and 100 atmospheres for 1 minute. The analytical data and reaction conditions of the reaction product are shown in Table 2 below. The hydrolyzate was found to contain 5 ppm of chromium and 7 ppm of molybdenum when measured with the same analyzer as in Comparative Example 4.

Embodiment 2

[0071] The same procedure as in Example 1 was carried out, except that a 3% by weight aqueous sodium carbonate solution was used instead of a 5% by weight aqueous sodium carbonate solution. The analytical data and reaction conditions of the reaction product are shown in Table 2 below.

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Abstract

Disclosed is a method for recovering toluene diamine from a fluid, high-boiling tar residue discharged from TDI preparation processes. After free TDI is separated and recovered from the tar residue, the remaining solid residue is pulverized, slurried and hydrolysis-treated in the presence of a catalyst under the condition of the liquid phase region near a critical point of water to produce toluene diamine, and then the resulting toluene diamine is effectively recovered.

Description

technical field [0001] The present invention relates to the recovery of toluene diamine from the high-boiling tar residue discharged from the toluene diisocyanate preparation process, more specifically, the present invention relates to a method for recovering toluene diamine from the high-boiling tar residue discharged from the bottom of the distillation tower during the toluene diisocyanate preparation process. A process for recovering toluene diamine, wherein, after separating and recovering free toluene diisocyanate contained in high-boiling tar residue, in the presence of a catalyst, at a high temperature close to the critical point of water, at a vapor pressure higher than the temperature Under the pressure (that is, the liquid region of water), the obtained solid residue is hydrolyzed to prepare toluenediamine, and then the obtained toluenediamine is recovered with high yield. The present invention also relates to economic efficiency and environmental friendliness by rec...

Claims

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Application Information

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IPC IPC(8): C07C209/86C07C211/51
CPCC07C209/86C07C211/51A61F2007/0045A61F2007/0098F25B29/00
Inventor 韩基道韩柱熙郑畅模申暎浩都承会韩基雨
Owner HANWHA CHEMICAL CORPORATION
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