Preparation method of glyoxalic acid monohydrate crystals

A glyoxylic acid monohydrate and crystallization technology, which is applied in the field of glyoxylic acid, can solve the problems of low purity of glyoxylic acid crystals, lack of production and application value, and low yield of glyoxylic acid products, reaching a strong market Competitiveness, convenient operation and control, good effect of herbicidal effect

Active Publication Date: 2016-06-15

WUHAN UNIV OF SCI & TECH +1

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AI-Extracted Technical Summary

Problems solved by technology

The purity of glyoxylic acid crystals obtained by crystallization is not high, and the color is difficult to reach white. Only one crystall...

Method used

This specific embodiment adopts novel precipitating agent to kill oxalic acid, has better herbicidal effect than calcifying agent generally used, has solved the difficult problem that the glyoxylic acid solution after the calcifying agent precipitation is placed to have precipitation again for a long time. Activated carbon is used to decolorize the glyoxylic acid solution, so that the color of the glyoxylic acid aqueous solution is significantly reduced, and the glyoxylic acid crystals are whiter. Low-boiling impurities present in the crude glyoxylic acid were removed by concentration under reduced pressure. By adding seed crystals and then cooling down to crystallize, glyoxylic acid can be better precipitated in the...

Abstract

The invention relates to a preparation method of glyoxalic acid monohydrate crystals. The technical scheme is as follows: the method comprises the following steps: heating a glyoxalic acid crude product, adding a precipitant, stirring, cooling, and carrying out vacuum filtration to obtain a filtrate I; adding activated carbon into the filtrate I, cooling, and carrying out vacuum filtration to obtain a filtrate II; concentrating the filtrate II under reduced pressure until the glyoxalic acid concentration is 55-67 wt%, thereby obtaining a crystallizing mother solution; transferring the crystallizing mother solution into a jacket crystallizing kettle, cooling, adding glyoxalic acid monohydrate crystals, keeping the temperature, cooling to -5 to 10 DEG C, and keeping the temperature to obtain a crystalline liquid; filtering the crystalline liquid to obtain a filtrate III and a filter cake; carrying out vacuum drying on the filter cake to obtain the glyoxalic acid monohydrate crystal crystals; treating the filtrate III by the process for treating the filtrate II to obtain a filtrate IV and glyoxalic acid monohydrate crystals; and treating the filtrate IV by the process for treating the filtrate II, thereby obtaining a filtrate V and the glyoxalic acid monohydrate crystals. The method is simple in technique, convenient to operate and suitable for industrial production. The prepared glyoxalic acid monohydrate crystals have the advantages of high purity and high yield.

Application Domain

Carboxylic compound separation/purification

Technology Topic

ChemistryActivated carbon +7

Examples

Experimental program(9)

Example Embodiment

[0022] Example 1

[0023] A method for preparing glyoxylic acid monohydrate crystals. The specific steps of the preparation method are:

[0024] Step 1. Heat the crude glyoxylic acid to 50-60°C, put in a precipitant, the molar ratio of the precipitant to the oxalic acid in the crude glyoxylic acid is 1-2:1, stir for 1-2 hours, and naturally cool to Filtrate I was obtained by suction filtration at room temperature. At 50-60°C, add activated carbon to the filtrate I, the activated carbon being 1 to 3 wt% of the filtrate I, stir for 2 to 3 hours, naturally cool to room temperature, and filter with suction to obtain filtrate II.

[0025] Step 2: At 50-55° C., the filtrate II is concentrated under reduced pressure to a glyoxylic acid concentration of 55-59 wt% to obtain a crystallization mother liquor.

[0026] Step 3. Transfer the crystallization mother liquor into a jacket crystallization kettle, and under stirring conditions, reduce the crystallization mother liquor in the jacket crystallization kettle to -1~3°C at a cooling rate of 2-10°C/hour , Then add glyoxylic acid monohydrate crystals as seed crystals, add 0.001 to 0.01wt% of the crystallization mother liquor, keep it for 1 to 2 hours; then add the seed crystals to the crystallization mother liquor at a cooling rate of 2-10°C/hour The temperature is lowered to -5~-7℃ and kept for 1~3 hours to obtain a crystalline liquid.

[0027] Step 4. Filter the crystal liquid under the protection of a dry atmosphere to obtain filtrate III and a filter cake; then vacuum dry the filter cake at 20-25°C for 10-15 hours to obtain glyoxylic acid monohydrate crystals Things.

[0028] Step 5: According to the method described in step 2 to step 4, treat the filtrate III with the method of treating the filtrate II, and obtain the filtrate IV and the glyoxylic acid monohydrate crystals successively.

[0029] Step 6. According to the method described in Step 2 to Step 4, treat the filtrate IV with the method of treating the filtrate II to obtain the filtrate V and the glyoxylic acid monohydrate crystals successively. The filtrate V can be used as the raw material for other products.

[0030] In this embodiment: the crude glyoxylic acid is a glyoxylic acid aqueous solution with a concentration of 40 to 45% by weight; the precipitating agent is zirconium dioxide; and the drying atmosphere is a dry air atmosphere.

[0031] The total yield of this example is 87.55 to 87.61%, the purity is 98.15 to 99.76%, and the appearance is white: the yield, purity and appearance of the glyoxylic acid monohydrate crystals obtained by three crystallizations are shown in Table 1. Narrate

[0032] Table 1

[0033] Product name

Example Embodiment

[0034] Example 2

[0035] A method for preparing glyoxylic acid monohydrate crystals. Except for the following parameters, the rest are the same as in Example 1:

[0036] In this embodiment: the precipitation agent is zirconium carbonate; the dry atmosphere is a nitrogen atmosphere.

[0037] The total yield of this example is 85.81-86.9%, the purity is 98.25-99.55%, and the appearance is white: the yield, purity and appearance of the glyoxylic acid monohydrate crystals obtained by three crystallizations are shown in Table 2. Narrate

[0038] Table 2

[0039] Product name

Example Embodiment

[0040] Example 3

[0041] A method for preparing glyoxylic acid monohydrate crystals. Except for the following parameters, the rest are the same as in Example 1:

[0042] In this embodiment: the precipitation agent is zinc oxide; the dry atmosphere is an oxygen atmosphere.

[0043] The total yield of this example is 85.21 to 87.01%, the purity is 98.19 to 99.65%, and the appearance is white: the yield, purity and appearance of the glyoxylic acid monohydrate crystals obtained by three crystallizations are shown in Table 3. Narrate

[0044] table 3

[0045] Product name

PUM

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Simple process

Preparation method of glyoxalic acid monohydrate crystals

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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