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Method and Application of Melting Crystallization to Separation of Dimethyl Carbonate Methanol Azeotrope

A dimethyl carbonate, melting and crystallization technology, applied in the chemical industry, to achieve low operating costs, high product purity, and safe operation

Active Publication Date: 2020-12-11
天津乐科节能科技有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For the solid-liquid phase equilibrium relationship of the DMC methanol azeotropic system and the separation of the DMC methanol azeotropic system by melting crystallization, there are no relevant reports for obtaining high-purity DMC products.

Method used

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  • Method and Application of Melting Crystallization to Separation of Dimethyl Carbonate Methanol Azeotrope
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  • Method and Application of Melting Crystallization to Separation of Dimethyl Carbonate Methanol Azeotrope

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] DMC methanol azeotropic composition, in which the DMC content is 33wt%, and the methanol content is 67wt%. It is passed into a continuous melting crystallizer, and the operating temperature in the crystallizer is controlled at -55 to -60°C. DMC is precipitated in the form of crystals, and in the crystallization system Suspension growth, where the continuous melting crystallizer can use a scraper type or a conventional kettle type cooling crystallizer, such as MSMPR type or DTB type crystallizer, in order to keep the crystallizer wall clean, a scraper can be set between the stirring blade and the crystallizer wall plate or brush. The crystal slurry mixture obtained through continuous crystallization enters the solid-liquid separator for solid-liquid separation to obtain DMC crude crystals and crystallization mother liquor. After this step of separation, the purity of DMC crude crystals can generally reach 97%-99%. The DMC content in the crystallization mother liquor is ...

Embodiment 2

[0030]DMC methanol azeotropic composition, in which DMC content is 35wt%, methanol content is 63wt%, and other organic impurities are 2%. It is passed into a continuous melting crystallizer, and the operating temperature in the crystallizer is controlled at -50 to -55°C. DMC is precipitated in the form of crystals. And it grows in suspension in the crystallization system. Here, the continuous melting crystallizer can adopt a scraper type or a conventional tank type cooling crystallizer, such as the MSMPR type or DTB type crystallizer. In order to keep the crystallizer wall clean, the stirring blade and the Scrapers or brushes are arranged between the walls of the crystallizer. The crystalline slurry mixture obtained through continuous crystallization directly enters the continuous liquid phase sweating section, where the sweating device can use a gravity washing tower, a mechanical washing tower or a hydraulic washing tower, and the corresponding solid phase DMC crystals are ma...

Embodiment 3

[0032] DMC methanol azeotropic composition, in which the DMC content is 30wt%, and the methanol content is 70wt%, which is passed into the intermittent melting crystallizer. Downward flow reduces boundary layer thickness and optimizes heat and mass transfer efficiency. Pass in cooling medium, first reduce the temperature of the feed liquid to -20°C, then control the cooling rate to 2-4°C / h, continue to cool the crystallization system to -50 to -55°C, and maintain a constant temperature for 2-3h. During this process, DMC is precipitated from the feed liquid in the form of layered crystals, and a DMC crystal layer is formed on the heat exchange wall. Drain the crystallization mother liquor to the mother liquor tank, switch the heat exchange medium, control the temperature of the heat exchange wall to 2-4°C, make the DMC crystal layer partially melt for sweating and purification, control the sweating liquid ratio to 4-6% of the crystal layer mass, put The sweating liquid is disc...

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Abstract

The invention relates to a method for separating dimethyl carbonate methanol azeotrope through melt crystallization and application thereof. The method specifically comprises the following steps: introducing a dimethyl carbonate methanol azeotrope with the dimethyl carbonate content of 25-35% into a melt crystallization device, separating out dimethyl carbonate in a crystal form through cooling, then partially melting dimethyl carbonate crystals through heating sweating, removing impurities contained in the crystallization process, further purifying dimethyl carbonate, and finally obtaining ahigh-purity dimethyl carbonate product and a low-concentration crystallization mother solution. The crystallization temperature of dimethyl carbonate in a self-azeotropic system is -20 to -40 DEG C, and the operation equilibrium temperature of a crystallization section is -50 to -60 DEG C, the purity of the dimethyl carbonate product is 99.9%-99.999%, and the concentration of the crystallization mother solution is 5%-15%. The method can be used for separation and purification of dimethyl carbonate methanol azeotropic composition in the process of producing dimethyl carbonate by a synthesis method or producing dimethyl carbonate as a byproduct in the coal-to-ethylene glycol process, and has the advantages of low energy consumption, high product purity and the like compared with traditionalseparation modes such as pressurized distillation, extractive distillation or azeotropic distillation.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a method for melting and crystallizing a dimethyl carbonate methanol azeotrope and an application thereof. Background technique [0002] Dimethyl Carbonate (DMC) is known as the "new cornerstone" of organic synthesis in the 21st century. In 1992, DMC passed the registration of non-toxic chemicals in Europe. Because its molecular structure contains various active functional groups such as carbonyl, methyl, methoxy, carbonylmethoxy, etc., it can carry out various organic Synthetic reaction, its excellent chemical properties enable it to replace some highly polluting and highly toxic chemicals, it is an environmentally friendly chemical raw material that meets the requirements of modern cleaning processes, and has broad application prospects. [0003] The synthesis process of DMC mainly includes phosgene methanol method, methanol oxidative carbonylation metho...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C68/08C07C69/96
CPCC07C68/08C07C69/96
Inventor 夏君君于会满尹海蛟全晓宇刘莉谢源圩
Owner 天津乐科节能科技有限公司
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