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Production process of dimethyl phthalate

A dimethyl phthalate and production process technology, applied in the field of dimethyl phthalate production process, can solve the problems of high product odor, unfavorable energy saving and emission reduction, high energy consumption, etc., and achieve the goal of reducing steam consumption Effect

Pending Publication Date: 2020-08-25
HANGZHOU QIANYANG TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because the raw material phthalic anhydride contains benzoic acid as a by-product, methyl benzoate will be generated during the reaction, and methyl benzoate has a strong smell, which will affect the use of high-end customers
At the same time, due to the presence of sodium ions in the production process, the by-product sodium monomethyl phthalate will be formed
The existence of these impurities affects the purity of the product and limits the field of use of customers
In order to solve these problems, some domestic manufacturers adopt rectification process for purification, but the energy consumption of rectification process is high, which is not conducive to energy saving and emission reduction
[0004] Methyl benzoate and sodium monomethyl phthalate were introduced into the raw materials or production process, which affected the purity of the product, and the product had a strong odor and the scope of application was limited
At present, some manufacturers use rectification process for purification, which consumes a lot of energy

Method used

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  • Production process of dimethyl phthalate
  • Production process of dimethyl phthalate
  • Production process of dimethyl phthalate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] see figure 1 , a production process of dimethyl phthalate, the production process comprising:

[0033] Step 1), esterification reaction:

[0034] Put phthalic anhydride and methanol into the esterification kettle with a molar ratio of 1:2, then add catalyst sulfuric acid with phthalic anhydride quality of 2‰, raise the temperature to 80°C for reflux reaction for 2 hours, raise the vacuum in the kettle to above 0.08MPa, and slowly exit the kettle Excess methanol in the tank and the water generated by the reaction until the temperature in the tank is 120°C, then add methanol to the tank while dehydrating at a temperature of 120°C under a vacuum degree of less than 0.01MPa, and carry out esterification until the acid value of the material is less than 4mgKOH / g, the esterification reaction time is 15 hours, and then the excess methanol is removed under a vacuum greater than 0.09MPa, and the dealcoholization temperature is 130°C to obtain a crude ester, which contains 98.5...

Embodiment 2

[0045] see figure 1 , a production process of dimethyl phthalate, the production process comprising:

[0046] Step 1), esterification reaction:

[0047] Put phthalic anhydride and methanol into the esterification kettle with a molar ratio of 1:2, then add catalyst sulfuric acid with phthalic anhydride quality of 2.5‰, raise the temperature to 95°C and reflux for 2.5 hours, raise the vacuum in the kettle to above 0.08MPa, and slowly exit the kettle Excess methanol in the tank and water generated by the reaction until the temperature in the tank is 128°C, and then add methanol to the tank while dehydrating at a temperature of 125°C under a vacuum degree of less than 0.01MPa, and carry out esterification reaction until the acid value of the material is less than 4mgKOH / g, the esterification reaction time is 13 hours, and then the excess methanol is removed under a vacuum greater than 0.09MPa, and the dealcoholization temperature is 136°C to obtain a crude ester, which contains ...

Embodiment 3

[0058] see figure 1 , a production process of dimethyl phthalate, the production process comprising:

[0059] Step 1), esterification reaction:

[0060] Put phthalic anhydride and methanol into the esterification kettle at a molar ratio of 1:2, then add catalyst sulfuric acid with phthalic anhydride quality of 3‰, heat up to 100°C and reflux for 3 hours, raise the vacuum in the kettle to above 0.08MPa, and slowly exit the kettle Excess methanol in the tank and water generated by the reaction until the temperature in the tank is 130°C, then dehydration is carried out while adding methanol to the tank at a temperature of 130°C under a vacuum degree of less than 0.01MPa, and the acid value of the material is less than 4mgKOH / g, the esterification reaction time is 12 hours, and then the excess methanol is removed under a vacuum greater than 0.09MPa, and the dealcoholization temperature is 140°C to obtain a crude ester, which contains 98.5-99% of dimethyl phthalate and benzoic ac...

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Abstract

The invention relates to a dimethyl phthalate production process for removing trace metal sodium ions in a product and reducing the content of methyl benzoate in the product. In the production process, after materials are neutralized and washed with water, the materials are treated, and an aqueous phosphoric acid or sulfuric acid solution with a concentration of 1-5% is mixed with the materials through sufficient stirring; and a steam stripping technology is adopted to bring a trace amount of methyl benzoate out of the product through steam stripping, so the content of methyl benzoate in the product is reduced. The production process is not limited by the quality of raw materials, and raw materials with higher benzoic acid impurity content in phthalic anhydride can also be used for producing high-purity dimethyl phthalate which is applied to essence and spice industries. Through ion exchange, metal ions in the product are removed, and the obtained product can be used in the industriesof electronics and the like. Through the above measures, high-quality dimethyl phthalate can be produced, and the high demand of high-end users is met.

Description

Technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a production process for dimethyl phthalate that removes trace metal sodium ions in a product and reduces the content of methyl benzoate in the product. Background technique [0002] Dimethyl phthalate (DMP) has strong solubility for a variety of resins and has good film-forming, adhesive and waterproof properties. It can be added to cellulose resin, acrylic resin and polyurethane resin in construction. It has a wide range of applications in materials, coatings, pesticides and cosmetics. In addition, it is often used in conjunction with diethyl phthalate in the production of cellulose acetate films, varnishes, translucent materials and molding powders. A small amount of it is used in the production of nitrocellulose. It can also be used as a plasticizer for nitrile rubber or as a raw material for the production of dicyclohexyl phthalate, high-carbon alcohol esters of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C67/08C07C67/48C07C67/60C07C69/80
CPCC07C67/08C07C67/48C07C67/60C07C69/80
Inventor 黄阳卫陈强兵丁翔陈勤勇边江
Owner HANGZHOU QIANYANG TECH
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