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Method for dehydrating and concentrating formaldehyde solution

A formaldehyde solution and solution technology, which is applied in chemical instruments and methods, preparation of organic compounds, separation/purification of carboxylic acid compounds, etc., can solve the problems of difficult recycling of formaldehyde and difficult conversion of formaldehyde.

Pending Publication Date: 2022-01-18
SOUTHWEST RES & DESIGN INST OF CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In addition, in the aldol condensation reaction, the raw material formaldehyde is usually difficult to completely convert, and the remaining formaldehyde and the water brought in by the raw material, the water generated by the reaction, or the water introduced by other methods form a mixed solution containing formaldehyde with a lower concentration, which is used for the recycling of formaldehyde bring great difficulty

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Experimental device: φ100×3800mm silver-plated rectification tower, filled with glass packing, the composition of formaldehyde-containing mixture solution is: 39wt% formaldehyde, 47wt% water, 13wt% acetic acid and other components, with methyl propionate as water The entrainer uses the azeotropy of methyl propionate and water to take out the water in the mixture to realize the concentration of formaldehyde. The mass ratio of the feed amount of the formaldehyde solution to the methyl propionate refluxed at the top of the rectification column is 1:6, the temperature at the top of the tower is 70°C, and the temperature at the bottom of the tower is 105°C.

[0020] The mixture of methyl propionate and water is extracted from the top of the tower, the tower bottom liquid contains 63wt% formaldehyde, 14wt% water, 20wt% acetic acid, 1.7wt% methyl propionate, and the mass ratio of formaldehyde to water in the bottom of the bottom is 4.5:1. The concentration of formaldehyde rela...

Embodiment 2

[0022] Experimental device: φ100×3800mm silver-plated rectification tower, filled with glass packing, the composition of formaldehyde-containing mixture solution is 50wt% formaldehyde, 43wt% water, 6wt% acetic acid and other components, with methyl propionate as water Boiling agent, using the azeotropy of methyl propionate and water to take out the water in the mixture to realize the concentration of formaldehyde. The mass ratio of the mixture solution to the reflux methyl propionate is 1:4, the temperature at the top of the tower is 68°C, and the temperature at the bottom of the tower is 104°C.

[0023] The mixture of methyl propionate and water is extracted from the top of the tower, the mass ratio of formaldehyde and water in the tower still liquid is 1.70:1, the concentration of formaldehyde relative to water is 62.96wt%, and the mass ratio of formaldehyde and water in the raw material mixture solution is 1.16:1, the concentration of formaldehyde relative to water is 53.70...

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PUM

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Abstract

The invention provides a method for concentrating a formaldehyde solution, belonging to the technical field of formaldehyde separation. The solution contains formaldehyde, water and carboxylic acid; the formaldehyde solution and a water entrainer are rectified; and the carboxylic acid in the solution enters the concentrated formaldehyde, and the formaldehyde solution and the water entrainer are returned together to serve as reaction raw materials to be recycled. The method for dehydrating and concentrating a formaldehyde solution provided by the inventions is particularly suitable for treating an unreacted formaldehyde solution produced in a synthesis process of unsaturated carboxylic acid or esters thereof through an aldol condensation method; and the formaldehyde-containing solution generally contains carboxylic acid, and by adopting the method, the carboxylic acid can be retained in the concentrated formaldehyde solution while the formaldehyde is concentrated, and the carboxylic acid is recycled as a reaction raw material.

Description

technical field [0001] The invention belongs to the technical field of methane recovery, in particular to a method for dehydrating and concentrating formaldehyde solution. Background technique [0002] Formaldehyde is a bulk chemical, and common specifications include 37wt.% and 55wt.% formaldehyde aqueous solutions, usually containing a small amount of methanol. Formaldehyde mainly forms complexes with water or methanol, and exists in the form of formaldehyde hydrate or hemiformal. [0003] Formaldehyde is used in the process of producing unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate by the aldol condensation method, and the industrial formaldehyde solution (concentration is 37wt.% and 55wt.%) that is easy to get is used as formaldehyde source. The introduction of water in the reaction will have an adverse effect on the catalyst, and may aggravate the hydrolysis reactions of ester reactants such as methyl acetate and methyl propionate a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C27/32C07C45/84C07C47/058C07C51/46C07C53/08
CPCC07C45/84C07C51/46C07C47/04C07C53/08
Inventor 王光永贾绘如李军谌晓玲王莉周拥华陈晓华应理李南锌
Owner SOUTHWEST RES & DESIGN INST OF CHEM IND