Method for concentrating at low temperature and pretreating concentrated solution

A pretreatment, low temperature technology, applied in chemical instruments and methods, preparation of organic compounds, preparation of hydroxyl compounds, etc., can solve the problems of difficult separation of trimethylolpropane, affecting product purity and color, etc.

Active Publication Date: 2009-12-02
NANTONG BAICHUAN NEW MATERIAL CO LTD +2
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Problems solved by technology

And because the relative volatility of MDF and trimethylolpropane is close to 1, it is difficult to realize separation (seeing Chinese patent ZL 99126564.5) from trimethylolpropane by means such as distillation, thus the purity and color of the product will be affected. Spend

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  • Method for concentrating at low temperature and pretreating concentrated solution
  • Method for concentrating at low temperature and pretreating concentrated solution
  • Method for concentrating at low temperature and pretreating concentrated solution

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[0040] Pump 1250kg of formaldehyde solution with a mass fraction of 37% into the batching kettle, add 2050kg of remixed water obtained from the dealdehyde / dealcoholization process for dilution, and make up the rest with deionized water to obtain 6000kg of dilute formaldehyde solution with a mass fraction of 8% ;

[0041] Turn on the freezer, turn on the stirring, freeze the formaldehyde solution used in the above reaction to 10°C, and then add the frozen dilute formaldehyde solution to the condensation kettle;

[0042] 339kg of n-butyraldehyde and 723kg of mass fraction of 32% liquid caustic soda are divided into two parts, the first part of n-butyraldehyde is 3 / 4 of the calculated mass of n-butyraldehyde, i.e. 254kg, and the remainder is the second part, liquid caustic soda The first part is 1 / 3 of the calculated mass of liquid caustic soda, i.e. 241kg, and the remainder is the second part. Add the first part of n-butyraldehyde and liquid caustic soda at a uniform speed of 25...

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Abstract

The invention relates to a method for concentrating at low temperature and pretreating concentrated solution. The method mainly comprises the following steps: 1, preparing mass percentage of formaldehyde solution for reacting to be between 3 and 15 percent; 2, adding frozen diluted formaldehyde solution into a concentration autoclave; 3, adding n-butyl aldehyde and alkali metal hydroxide solution into the autoclave by two parts for two times; 4, dripping methanoic acid into concentrated solution; 5, pumping the acidified concentrated solution into a formaldehyde stripping tower to remove formaldehyde, methanol and partial water; and 6, pumping distillate into a dealcoholizing tower if the mass percentage of the methanol in the distillate obtained in the step five exceeds 2 percent, and distilling the methanol thereinto under normal pressure condition. The concentrated solution obtained through low temperature concentration, step feed and pressurized formaldehyde stripping / dealcoholizing pretreatment has high selectivity, can effectively prevent the formaldehyde, the methanol and the like from reacting with trimethylolpropane in subsequent separating and refining processes and generating unexpected byproducts, thereby improving the quality and the yield of the trimethylolpropane.

Description

(1) Technical field [0001] The invention relates to a method for controlling the condensation reaction of n-butyraldehyde and formaldehyde solution and pretreating the condensation liquid so as to improve the selectivity of the target product—trimethylolpropane and reduce the color number of the condensation liquid. It belongs to the technical field of organic chemical products. (2) Background technology [0002] Trimethylolpropane is a chain extender commonly used in the resin industry. It has a low melting point and has 3 methylol groups on the α position of the molecule. It can react with organic acids to form monoesters or polyesters, react with aldehydes and ketones to form acetals and ketals, and react with diisocyanates to form carbamates. Wait. It can improve the firmness, corrosion resistance and sealing of the resin, and has good stability for hydrolysis, pyrolysis and oxidation processes. [0003] At present, the production method of trimethylolpropane at home ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C31/22C07C29/38
Inventor 郑铁江吴晓明薛建军
Owner NANTONG BAICHUAN NEW MATERIAL CO LTD
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