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Method for recovering TDA (Toluene Diamine) from residues and wastes formed in preparation process of TDI (Toluene Diisocyanate)

A technology of toluene diisocyanate and preparation process, which is applied in the field of recycling chemical raw materials, can solve problems such as environmental pollution, waste of resources, etc., and achieves the effects of significant economic benefits, reduced viscosity and mild reaction.

Inactive Publication Date: 2014-05-14
UNIV OF JINAN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Not only wasting the resources in the residue, but also causing some pollution to the environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Weigh 12 g of crushed TDI distillation residue and 100 g of ethylene glycol into a reactor with a capacity of 200 mL equipped with a stirrer, a reflux condenser and a thermometer, and heat it. When the temperature rises to 100 ° C, add 8 g TDI residue and heated to about 190°C until the system boiled, and kept at reflux for 1.5 h.

[0034]Maintain the temperature at 190°C, add 5 g of triethylenetetramine to the reactor at a rate of 10 mL / h, and then, after cooling down to 100°C, add 10 g of 50% triethylenetetramine at a flow rate of 5 mL / h NaOH aqueous solution. During the dropwise addition, the system temperature was kept at 100°C. The reaction was timed for 5 h from the time NaOH was added. Finally, 40 mL of water was added at a flow rate of 20 mL / h, and gel was formed in the system. After the dropwise addition, the heating was stopped, and the material was cooled and discharged. The resulting product was filtered to remove the residue to obtain a dark brown filtra...

Embodiment 2

[0036] Weigh 12 g of crushed TDI distillation residue and 80 g of ethylene glycol and add them to a reactor equipped with a stirrer, reflux condenser and thermometer and heat them. When the temperature rises to 100°C, add 8 g of TDI residue and Heat to about 190°C until the system boils, and keep refluxing for 1.5 h. All the other steps are the same as in Example 1. The TDA yield that obtains is 55% that adds TDI solid residue quality.

Embodiment 3

[0038] Weigh 12 g of crushed TDI distillation residue and 100 g of ethylene glycol and add them to a reactor equipped with a stirrer, reflux condenser and thermometer and heat them. When the temperature rises to 100°C, add 8 g of TDI residue and Heat to about 190°C until the system boils, and keep refluxing for 1.5 h.

[0039] Maintain the temperature at 190°C, add 10 g of triethylenetetramine to the reactor at a rate of 20 mL / h, and then, after cooling down to 100°C, add 10 g of 50% triethylenetetramine at a flow rate of 5 mL / h NaOH aqueous solution. All the other steps are the same as in Example 1. The TDA yield that obtains is 57% that adds TDI solid residue mass.

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Abstract

The invention relates to a method for preparing an important chemical raw material TDA (Toluene Diamine) by carrying out chemical treatment at ordinary pressure on residues and wastes formed in the preparation process of TDI (Toluene Diisocyanate). The method comprises the steps of heating a mixture of crushed TDI residues and ethylene glycol at ordinary pressure till boiling reflux; then adding triethylenetetramine and a NaOH water solution, continuously reacting at 100 DEG C, and finally adding water to a system for cooling to obtain a primary hydrolysis product; carrying out salting-out on the hydrolysis product through a saturated sodium chloride solution, carrying out fractional extraction on the hydrolysis product through dichloromethane, and then carrying out reduced pressure distillation on an extract to prepare the TDA. According to the invention, the yield of the TDA accounts for 60% of the weight of added TDI solid residues, and the purity of the TDA is 95%. The method disclosed by the invention carries out hydrolysis on the TDI residues at ordinary pressure without needing a high-pressure reaction kettle, thereby greatly reducing the cost of production equipment; the method disclosed by the invention is outstanding in economic benefit.

Description

technical field [0001] The present invention relates to a method for recovering chemical raw materials from chemical residues, in particular to a method for recovering toluene diamine (TDA) from residue waste produced during the preparation of toluene diisocyanate (TDI), to solve the problem of TDI residues The issue of recycling involves improving economic benefits and solving the problem of environmental pollution caused by residues. [0002] Background technique [0003] TDI is an important chemical raw material, which is widely used in the production of polyurethane and can be used in many fields such as foam plastics, elastomers, coatings and adhesives. At present, the method of industrially synthesizing TDI is mainly the phosgene method using TDA as raw material. The obtained TDI will be purified through a distillation tower, and high-boiling residues will be formed at the bottom of the tower. These residues are in the tar state containing a small amount of TDI and b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C211/51C07C209/00C07C209/86
Inventor 孔祥正姜绪宝张春光朱晓丽
Owner UNIV OF JINAN
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