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Production method for methylacrolein

A technology of methacrolein and production method, which is applied in chemical instruments and methods, separation/purification of carbonyl compounds, preparation of carbonyl compounds, etc., can solve problems such as material consumption, increased energy consumption, burden and the like

Inactive Publication Date: 2015-01-28
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

CN101074192A, CN102659542A etc. set forth that the used formaldehyde of the method for preparing MAL is its aqueous solution (formalin), but the water content of formalin is as high as 62%, even if the yield of MAL is calculated by 100%, the MAL of producing 1t It will also produce at least 700kg of waste water introduced by formalin, which accounts for at least 72% of the total waste water produced in the production process. This part of water will enter the ionic liquid catalyst with the reaction, which will give the separation of the subsequent ionic liquid catalyst , Recycling brings a heavy burden, and the material consumption and energy consumption in the production process will inevitably increase greatly

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0010] Add 600 g of methanol and 0.4 g of potassium hydroxide (the pH value after dissolution is about 10) to the 5L jacketed glass reactor equipped with a stirring controller, condenser, thermometer and constant pressure dropping funnel, adjust and control the The water temperature of the circulating water in the jacket, after the temperature of the feed liquid is stabilized at 50°C, 372g of paraformaldehyde is added, and a clear and transparent solution is obtained after depolymerization for 4 hours. The depolymerization liquid was lowered to normal temperature, and the formaldehyde content in the obtained paraformaldehyde depolymerization liquid was measured to be 38.2%.

[0011] Continue to add 1200g diethylamine hydrochloride ionic liquid (water content 14.2%) and hydroquinone 0.5g in the kettle, adjust and control the temperature of the circulating water in the jacket, after the temperature of the reaction feed liquid is stabilized at 45°C, the 580g The propionaldehyde w...

Embodiment 2

[0015] Add isopropanol 600g, diethylamine 0.7g (the pH value after dissolving is about 11) successively in the 5L jacketed glass reaction kettle that is equipped with stirring controller, condensing tube, thermometer and constant pressure dropping funnel, adjusts and Control the temperature of the circulating water in the jacket, and add 391 g of paraformaldehyde after the temperature of the feed liquid is stabilized at 60° C., and obtain a clear and transparent solution after depolymerization for 6 hours. The depolymerization liquid was lowered to normal temperature, and the formaldehyde content in the obtained paraformaldehyde depolymerization liquid was measured to be 39.4%.

[0016] Continue to add 1300g diethanolamine sulfate ionic liquid (water content 17.6%) and o-benzoquinone 0.1g in the above-mentioned kettle, adjust and control the temperature of the circulating water in the jacket, after the temperature of the reaction feed liquid is stabilized at 30°C, add 580g of a...

Embodiment 3

[0018] Examples of repeated use of ionic liquid catalysts.

[0019] The depolymerization experiment was the same as in Example 2, and the formaldehyde content of the formaldehyde organic solution was measured to be 39.3%.

[0020] Continue to add the ionic liquid catalyst recovered in Example 2 to the kettle, adjust and control the temperature of the circulating water in the jacket, and after the temperature of the reaction feed liquid is stabilized at 30°C, drop 580 g of propionaldehyde into the kettle through a constant pressure dropping funnel , the dropping time is 90min. After dropping the propionaldehyde and continuing to react for 40 minutes, sampling and analysis showed that the conversion rate of propionaldehyde was 99.3%, and the selectivity of methacrolein was 99.8%. The resulting feed liquid was separated by a rectification tower, and the fraction at 67-69°C was collected. The mass of the obtained MAL was 687g, and the catalyst could be reused after removing 178g ...

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Abstract

The invention relates to a production method for methylacrolein. The production method comprises the steps of depolymerizing paraformaldehyde in an organic solvent so as to produce a methanal organic solution, and carrying out aldol condensation reaction on the methanal organic solution and propyl aldehyde under the catalysis of ionic liquid so as to produce methylacrolein. According to the production method, the methanal organic solution obtained through depolymerization of paraformaldehyde substitutes for methanal water solution, so that a lot of waste water is prevented from the source, the output of the waste water is greatly reduced in production, and the burden of recycling of ionic liquid is relieved; furthermore, due to the organic solvent used in the depolymerization, the oil-water separation in aldol condensation reaction is changed into homogeneous reaction, so that the mass transfer rate is accelerated, and the conversion rate and selectivity of the reaction are further improved.

Description

technical field [0001] The invention relates to a production method for preparing methacrolein through aldol condensation of paraformaldehyde depolymerization liquid and propionaldehyde. In particular, it relates to an improved method for improving the conversion rate of propionaldehyde, the selectivity of methacrolein and reducing the discharge of waste water, which belongs to the field of green chemical industry. Background technique [0002] Methacrolein (MAL) is an important α, β-unsaturated aldehyde, which has the characteristics of both olefins and aldehydes, and can be used to synthesize methacrylic acid, methallyl alcohol, methyl methacrylate (MMA) And various chemical products such as isopropyl methacrylate. Among them, MMA is an important plexiglass monomer, and MMA can also be used in the textile size and coating industries, with a wide range of uses and a large amount. Therefore, MAL, as an important intermediate required in the synthesis and production process...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C47/22C07C45/75
CPCC07C45/75C07C45/00C07C45/82C07C47/22C07C47/04
Inventor 孟晓山刁琰琰冯鹏飞杨普王玲张锁江
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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