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Method for removing formaldehyde and methanol from carboxylic ester containing material and application

A carboxylate and logistics technology, applied in the field of separation technology, can solve the problems of difficult separation, easy polymerization, high energy consumption for formaldehyde recycling and utilization, and achieve the effects of high economy, simple process and high industrial application value.

Active Publication Date: 2018-06-08
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Formaldehyde is easy to polymerize, causing pipeline blockage and loss of raw materials
Methanol has a strong ability to dissolve water and organic matter. When the methanol content in the reaction solution is high, the conventional extraction method is prone to emulsification and separation is difficult.
[0004] CN1111151C takes water and methyl propionate as extraction agent, formsaldehyde is removed in the reaction liquid that produces MMA by aldol condensation, but the energy consumption of unreacted formaldehyde recovery in the water phase is higher, and does not relate to how to formaldehyde from reaction liquid Simultaneous separation of high concentration formaldehyde and methanol
[0005] CN106699560A uses glycerin aqueous solution as extractant to separate and purify MMA in the aldol condensation reaction solution, but the methanol content in the reaction solution composition is low (below 10%), and the formaldehyde content is not given in the reaction solution
In addition, glycerin has a high boiling point and high viscosity, which is not conducive to the recovery and utilization of extractants.
[0006] CN103833551A has introduced a kind of purification separation method that produces MMA by the oxidation of tert-butanol / isobutylene, adopts n-hexane and water to extract and purify MMA, but the composition of reaction solution of this process and the composition of reaction solution of aldol condensation reaction produce MMA are very different, this The patent also does not mention whether the extraction process is suitable for the separation of the latter
[0007] CN1023799C adopts the method of azeotropic distillation to separate the methanol in the MMA stream, when the methanol content is high, the energy consumption is high and uneconomical
In the current published patents and related documents, there is no report on the effective removal of high-concentration formaldehyde and methanol in the MMA-containing stream

Method used

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  • Method for removing formaldehyde and methanol from carboxylic ester containing material and application
  • Method for removing formaldehyde and methanol from carboxylic ester containing material and application
  • Method for removing formaldehyde and methanol from carboxylic ester containing material and application

Examples

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Embodiment 1

[0061] In this embodiment, the extractant A is dimethyl sulfoxide, and the extractant B is cyclohexane, ε A = 48.9, ε B = 2.02.

[0062] Through the aldol condensation reaction of methyl propionate and formaldehyde, stream 1 containing carboxylic acid esters was obtained. After testing, the composition of stream 1 containing carboxylic acid esters was: 8.66 wt% formaldehyde, 38.80 wt% methanol, and 45.73 methyl propionate. wt%, methyl methacrylate (abbreviated as MMA) 5.77 wt%, water 1.04 wt%.

[0063] (1) The stream 1 containing carboxylic acid ester is subjected to pre-rectification treatment to remove part of methanol as an azeotrope of methanol and methyl propionate. The operating conditions of the rectification tower are atmospheric pressure, 25°C operating temperature, 20 theoretical plates, stream 1 containing carboxylic acid ester is fed into the eighth plate, and the top temperature of the rectification tower is 62.5°C. The temperature is 75°C, the reflux ratio is 1, the ...

Embodiment 2

[0067] In this embodiment, the extractant A is dimethyl sulfoxide, and the extractant B is cyclohexane, ε A = 48.9, ε B = 2.02.

[0068] Through the aldol condensation reaction of methyl propionate and formaldehyde, stream 2 containing carboxylic acid ester is obtained. After testing, the composition of stream 2 containing carboxylic acid ester is: formaldehyde 5.07% by weight, methanol 22.1% by weight, and methyl propionate 52% by weight %, methyl methacrylate 17.65wt%, water 3.18wt%.

[0069] (1) The stream 2 containing carboxylic acid esters is subjected to pre-rectification treatment, and part of the methanol is removed in the form of an azeotrope of methanol and methyl propionate. The operating conditions of the rectification column are normal pressure and 25 ℃, the number of theoretical plates is 20 plates, the feed position of stream 1 is at the tenth plate, the top temperature is 62.5℃, the bottom temperature is 75℃, the reflux ratio is 0.7, the feed flow rate is 1.51kg / h, ...

Embodiment 3

[0073] The pre-rectified stream 2 containing carboxylic acid esters in Example 2 was input from the middle of the extraction tower at a mass flow rate of 1 kg / h; at the same time, dimethyl sulfoxide was discharged from the top of the extraction tower at a mass flow rate of 0.5 kg / h. Into the tower, the cyclohexane is fed into the tower internal stream from the bottom of the extraction tower at a mass flow of 0.5kg / h. The cyclohexane and dimethyl sulfoxide are in countercurrent contact in the tower and are extracted step by step. Finally, 1.2 kg / h of light components were obtained from the upper section of the extraction tower, and 0.38 kg / h of heavy components were obtained from the lower section of the extraction tower. The operating pressure of the extraction tower is normal pressure, the operating temperature is 25°C, and the theoretical number of stages is 5.

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Abstract

The invention provides a method for removing formaldehyde and methanol from a carboxylic ester containing material. The method comprises the following steps: a) subjecting the carboxylic ester containing material to pre-distillation treatment so as to remove a part of an azeotrope; and b) subjecting the pre-distilled carboxylic ester containing material, an extractant A and an extractant B to reverse contacting in an extraction device so as to obtain a light component through extraction of the extractant A and obtain a heavy component through extraction of the extractant B; wherein reverse contacting in the step a) is performed as follows: dissolving the carboxylic ester containing material in the extractant B and carrying out contacting with the extractant A during flowing in a reverse direction, or adding the carboxylic ester containing material in the contacting process of the extractant B and the extractant A during flowing in the reverse direction. The extraction separation process provided by the invention breaks an azeotropic system, and high-purity carboxylic ester can be obtained through simple distillation of an organic phase obtained by separation.

Description

Technical field [0001] The invention relates to a method for simultaneously removing high-concentration formaldehyde and methanol, in particular to the application of the method in the separation process of a reaction solution for producing methyl methacrylate by aldol condensation, and belongs to the technical field of separation processes. Background technique [0002] Compared with the traditional acetone cyanohydrin method and isobutylene oxidative esterification method, the two-step method for producing methyl methacrylate (MMA) with ethylene as the raw material (hereinafter referred to as the α-MMA process) has a shorter process flow and less equipment investment. And other advantages, the most competitive in environmental protection and economy. [0003] In the α-MMA process, ethylene undergoes an oxo reaction to produce methyl propionate, which undergoes aldol condensation with formaldehyde to produce MMA. Among them, the separation of the aldol condensation reaction produ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C69/003C07C69/54C07C67/54C07C67/58
CPCC07C67/54C07C67/58C07C69/003C07C69/54
Inventor 于海彬胡进姜庆梅万毅李庆志韩红宇初乃波黎源华卫琦
Owner WANHUA CHEM GRP CO LTD
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