Decolorizing method of (meth)acrylic acid

A technology of methacrylic acid mother and acrylic acid is applied in the field of decolorizing chemical raw materials in the process of refining and purification, which can solve the problem of high operating costs and achieve the effects of low energy consumption and high efficiency

Active Publication Date: 2014-06-04
SHANGHAI HUAYI NEW MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Moreover, by-products such as heavy components, waste water, and waste gas separated by rectification and purification need to be purified before they can be discharged, and the total operating cost is relatively high.

Method used

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  • Decolorizing method of (meth)acrylic acid
  • Decolorizing method of (meth)acrylic acid
  • Decolorizing method of (meth)acrylic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] (1) Get the acrylic acid mother liquor and carry out crystallization

[0037] Get a certain amount of rough rectification, acrylic acid mother liquor (1 ton-100 tons, can be adjusted according to the needs of production capacity) that purity is 90-95% by weight, pump it to crystallizer with certain rate (crystallizer size is 1m 3 -100m 3 , can be adjusted according to production capacity requirements), and at the same time, the refrigerator is turned on for refrigeration. Methanol or ethanol as the heat exchange medium enters from the shell of the crystallizer, and the temperature of the crystallization tube is slowly cooled from normal temperature to -17°C. The cooling rate is 1°C / min. The crystallization time is controlled to be 30-40 minutes, the crystallization pressure is controlled to be 40-60 kPaG, and the temperature of the acrylic acid is lowered from normal temperature to -15--20° C., so that all acrylic acid crystals are attached to the wall of the crystall...

Embodiment 2

[0050] (1) Get methacrylic acid mother liquor and carry out crystallization

[0051] Same as Example 1, get a certain amount of crude distillation, methacrylic acid mother liquor (1 ton-100 tons, can be adjusted according to production capacity needs) with a purity of 90-95% by weight, and pump it to Crystallizer (the crystallizer size is 1m 3 -100m 3 , can be adjusted according to production capacity requirements), and at the same time, the refrigerator is turned on for refrigeration. Methanol or ethanol as the heat exchange medium enters from the shell of the crystallizer, and the temperature of the crystallization tube is slowly cooled from normal temperature to -18°C. The cooling rate is 1.5°C / min. The crystallization time is controlled to be 30-40 minutes, the crystallization pressure is controlled to be 20-50 kpaG, the temperature of the methacrylic acid is lowered from normal temperature to -15--20° C., so that all methacrylic acid crystals are attached to the crystal...

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Abstract

The invention discloses a decolorizing method of (meth)acrylic acid. The decolorizing method is characterized by employing a falling film crystallization technology. The used technology comprises the following steps: a) adding 90-95wt% of acrylic acid or methacrylic acid mother liquor into a crystallizer in accordance with the capacity of the crystallizer; b) starting a freezer, and then operating the crystallizer under required temperature and pressure conditions; c) circulating the acrylic acid or methacrylic acid mother liquor at a certain rate, and cooling for crystallization; d) melting the crystallized part, and cutting the residual liquid in a certain ratio; e) adding 75wt% of polymerization inhibitor (150+ / -20 ppm) when the melting of the crystallized part is soon finished; f) completely melting the crystal, cutting the residual liquid in a certain ratio, adding the remaining 25wt% of polymerization inhibitor (50+ / -20 ppm), and returning the obtained product to a raw material tank; and g) repeating the above steps from a) to f) for secondary crystallization, and conveying the obtained product into a finished product tank. The decolorizing method has the advantages of high efficiency, low energy consumption, no byproduct generation, no pollution and the like.

Description

technical field [0001] The invention relates to a method for decolorizing chemical raw materials in the process of refining and purifying, in particular to a method for decolorizing acrylic acid or methacrylic acid with a crystallization purity of 90-95% by weight . Background technique [0002] Acrylic acid and methacrylic acid are important chemical raw materials. The unsaturated double bonds (active vinyl groups) contained in them have high polymerization activity, so they can be widely used as polymerization monomers to prepare various polymers. [0003] Chemically synthesized or isolated acrylic or methacrylic compounds usually contain various impurities. This impurity usually affects the chroma of acrylic acid or methacrylic acid, and then adversely affects the production of downstream products. Therefore, it is necessary to remove this part of impurities through purification to make the chroma of acrylic acid or methacrylic acid reach the standard. At present, there...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C57/07C07C51/43
Inventor 仇佳葵罗明陨钱志刚马建学褚小东邵敬铭谢佳
Owner SHANGHAI HUAYI NEW MATERIAL
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