CN115806473B - Method for removing macromolecular impurities of pentaerythritol formal - Google Patents
Method for removing macromolecular impurities of pentaerythritol formal Download PDFInfo
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- CN115806473B CN115806473B CN202211570540.4A CN202211570540A CN115806473B CN 115806473 B CN115806473 B CN 115806473B CN 202211570540 A CN202211570540 A CN 202211570540A CN 115806473 B CN115806473 B CN 115806473B
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Abstract
The invention discloses a method for removing macromolecular impurities of pentaerythritol formal, which sequentially comprises three steps of condensation reaction, adsorption and catalytic decomposition, wherein pentaerythritol is produced intermittently by a sodium method, formaldehyde and acetaldehyde are used as raw materials for condensation reaction under the catalysis of liquid alkali, the condensation reaction stops neutralizing the liquid alkali with formic acid to stop the reaction, then the PH of the reaction is regulated to about 6 by using formic acid, and then 99-grade pentaerythritol finished products are obtained through the procedures of rectification, evaporation, crystallization, separation, washing and drying. The control of condensation reaction is adopted, and the physical adsorption is utilized to reduce the pentaerythritol formal content in the condensation liquid from 3.5% to 2%; the content of pentaerythritol formal and macromolecules is reduced to 1% by cation exchange resin, and the content of the obtained 98-grade pentaerythritol is increased to 99%.
Description
Technical Field
The invention belongs to the technical field of chemical production methods, and particularly relates to a method for removing macromolecular impurities of pentaerythritol formal.
Background
The formaldehyde and the acetaldehyde are subjected to condensation reaction under alkaline condition to produce pentaerythritol, the process taking sodium hydroxide as raw material is sodium method process, other side reactions are generated to produce impurities during intermittent condensation reaction, and except for by-products in double seasons, the maximum amount of pentaerythritol formal and other macromolecular impurities are used. These impurities are organic matters, the separation difficulty is high, and the product quality can be influenced by incomplete separation. The pentaerythritol formal content in the 90-level pentaerythritol reaches 8 percent, and the pentaerythritol formal content in the 98-level pentaerythritol reaches 1 percent. The produced impurities seriously affect the quality of the product, and the conventional production adopts a hydrolysis method under an acidic condition, but the hydrolysis method under the acidic condition has the problems of high acid concentration requirement, high hydrolysis temperature, long hydrolysis time, incomplete hydrolysis, easy equipment corrosion and the like.
According to the principle of physical adsorption and chemical adsorption, partial impurities are removed by physical adsorption and physical adsorbents such as cellulose, activated carbon, molecular sieves, silicon oxide, aluminum oxide and the like. And then, a cation exchange resin is used for providing free H+, and the principle of chemical adsorption is utilized for decomposing macromolecular impurities such as residual pentaerythritol formal and the like. By adopting the two modes, the hydrolysis condition is reduced, and equipment is not corroded. The cation exchange resin is regenerated by acid and can be recycled, but the method has the problems of high resin price, easy pollution, relatively short service life and the like.
Disclosure of Invention
The invention provides a method for removing macromolecular impurities of pentaerythritol formal in order to overcome the defects in the prior art.
The invention is realized by the following technical scheme: the invention discloses a method for removing macromolecular impurities of pentaerythritol formal, which sequentially comprises three steps of condensation reaction, adsorption and catalytic decomposition, wherein pentaerythritol is intermittently produced by adopting a sodium method, formaldehyde and acetaldehyde are used as raw materials for condensation reaction under the catalysis of liquid alkali, the condensation reaction stops neutralizing the liquid alkali with formic acid to stop the reaction, then the PH of the reaction is regulated to 5.8-6.2 with formic acid, and then 99-grade pentaerythritol finished product is obtained through rectification, evaporation, crystallization, separation, washing and drying procedures, so that the macromolecular impurities of the pentaerythritol formal in the product are greatly reduced;
step 1, condensation reaction: the pentaerythritol is subjected to condensation reaction by taking formaldehyde and acetaldehyde as raw materials under the catalysis of liquid alkali, and is subjected to high-proportion feeding reaction, and the reaction termination temperature is controlled to be lower than 42-45 ℃, so that the generation of pentaerythritol formal is effectively reduced;
step 2, adsorption: the condensation liquid after the reaction passes through an adsorption device at the temperature of 60-90 ℃, and the adsorbent is a physical adsorbent and is used for removing part of pentaerythritol formal;
step 3, catalytic decomposition: the condensed liquid after adsorption is subjected to heat exchange to 90-130 ℃ and the retention time is 2-4 h, and a small amount of formal is decomposed by cation exchange resin.
As a preferred embodiment of the present invention, the condensation reaction is terminated by neutralizing the liquid alkali with formic acid, then adjusting the pH to about 5 with formic acid, and in the condensation reaction of step 1, the reaction termination temperature is controlled to be lower than 45 ℃.
As a preferred embodiment of the present invention, in the adsorption of step 2, the acetal content in the condensed liquid is reduced from 3.5% to 2% by physical adsorption by controlling the condensation reaction, and adsorbing the condensed liquid at a temperature of 70 to 80 ℃ for 0.5 to 1 hour. The physical adsorbent is one or more of cellulose, activated carbon, molecular sieve, silicon oxide or aluminum oxide.
As a preferred embodiment of the invention, in the step 3 catalytic decomposition, the condensed liquid after adsorption is subjected to heat exchange to 100-120 ℃ for 3 hours, so that the formal and macromolecular content is reduced to 1%
The beneficial effects of the invention are as follows: the invention discloses a method for removing macromolecular impurities such as pentaerythritol formal from pentaerythritol, which adopts a sodium method to intermittently produce pentaerythritol, takes formaldehyde and acetaldehyde as raw materials to carry out condensation reaction under the catalysis of liquid alkali, the reaction is stopped, formic acid is used for neutralizing the liquid alkali to stop the reaction, then formic acid is used for regulating the PH to about 5, and the 99-grade pentaerythritol finished product is obtained through the procedures of rectification, evaporation, crystallization, separation, washing, drying and the like. The invention can greatly reduce the pentaerythritol formal content in the product through the measures. The invention can realize the reliable separation of pentaerythritol and impurities and improve the content of pentaerythritol. The method of the invention needs an adsorption device capable of removing macromolecular impurities such as pentaerythritol formal and the like, and also can use a catalytic decomposition device for carrying out fixed catalytic decomposition on the residual formal.
The invention generates pentaerythritol formal in the industrial production of pentaerythritol, and adopts adsorption materials such as cellulose, activated carbon, molecular sieve, silicon oxide, aluminum oxide, cation exchange resin and the like by utilizing the principles of physical adsorption and chemical adsorption. The condensation reaction is controlled, the condensation liquid is adsorbed for 1h at the temperature of 60-90 ℃, and the acetal content in the condensation liquid is reduced from 3.5% to 2% by physical adsorption. Through cation exchange resin, the retention time is 2-4 h at 90-120 ℃, the formal and macromolecular content is reduced to 1%, the obtained 98-grade pentaerythritol content is increased to 99%, and the sodium formate content is increased to 99%.
Drawings
FIG. 1 is a flow chart of the method for removing macromolecular impurities such as pentaerythritol formal from pentaerythritol according to the invention.
Detailed Description
The invention is described in detail below with reference to the drawings and the specific embodiments.
Example 1: as shown in figure 1, in the method for removing macromolecular impurities such as pentaerythritol formal from pentaerythritol, formaldehyde and acetaldehyde undergo condensation reaction under the condition of liquid alkali, the termination temperature is controlled to be lower than 45 ℃, and the acetal content is controlled to be about 3.5%. The condensation liquid after reaction is subjected to physical adsorption at 75-90 ℃ to ensure the retention time to be 0.5h, and the acetal content of the condensation liquid after adsorption is reduced to 1.5% through adsorption layers such as cellulose, activated carbon, molecular sieve, silicon oxide, alumina and the like. The condensed liquid after adsorption is continuously heated, enters a chemical adsorption device, stays for 3 hours at the temperature of 100-120 ℃, and the residual aldehyde content in the condensed liquid is reduced to 0.5%.
Example 2: as shown in FIG. 1, in the method for removing macromolecular impurities such as pentaerythritol formal from pentaerythritol, formaldehyde and acetaldehyde undergo condensation reaction under the condition of liquid alkali, the termination temperature is controlled to be more than 45 ℃, and the acetal content is controlled to be about 4.2%. The condensation liquid after reaction passes through a physical adsorption tower at 50-75 ℃ to ensure the residence time to be 0.5h, the condensation liquid passes through adsorption layers such as cellulose, activated carbon, molecular sieve, silicon oxide, aluminum oxide and the like, and the pentaerythritol formal content of the condensation liquid after adsorption is reduced to 2.3 percent. Heating the adsorbed condensed liquid, entering a chemical adsorption device, and keeping the condensed liquid at 90-100 ℃ for 3 hours, wherein the content of pentaerythritol formal in the condensed liquid is reduced to 1%.
Finally, it should be noted that the above description is only for illustrating the technical solution of the present invention, and not for limiting the scope of the present invention, and that the simple modification and equivalent substitution of the technical solution of the present invention can be made by those skilled in the art without departing from the spirit and scope of the technical solution of the present invention.
Claims (2)
1. A method for removing macromolecular impurities of pentaerythritol formal is characterized by comprising the following steps: the method sequentially comprises three steps of condensation reaction, adsorption and catalytic decomposition, wherein a sodium method is adopted to intermittently produce pentaerythritol, formaldehyde and acetaldehyde are used as raw materials to carry out condensation reaction under the catalysis of liquid alkali, the condensation reaction is stopped, formic acid is used for neutralizing the liquid alkali to stop the reaction, then formic acid is used for regulating the PH to 5, and then the 99-grade pentaerythritol finished product is obtained through the working procedures of rectification, evaporation, crystallization, separation, washing and drying, so that macromolecular impurities of pentaerythritol formal in the product are greatly reduced;
step 1, condensation reaction:
the pentaerythritol is subjected to condensation reaction by taking formaldehyde and acetaldehyde as raw materials under the catalysis of liquid alkali, and is subjected to high-proportion feeding reaction, and the reaction termination temperature is controlled to be lower than 45 ℃, so that the generation of pentaerythritol formal is effectively reduced;
step 2, adsorption:
adsorbing the condensation liquid after the reaction for 0.5 to 1 hour by an adsorption device at the temperature of between 70 and 80 ℃, and reducing the acetal content in the condensation liquid from 3.5 percent to 2 percent by physical adsorption, wherein the adsorbent is a physical adsorbent and is used for removing part of pentaerythritol formal;
step 3, catalytic decomposition:
the condensed liquid after adsorption is subjected to heat exchange to 90-150 ℃ and the retention time is 2-4 h, and a small amount of formal is decomposed by cation exchange resin;
in the step 2 adsorption, the physical adsorbent is one or more of cellulose, activated carbon, molecular sieve, silicon oxide or aluminum oxide.
2. The method for removing macromolecular impurities from pentaerythritol formal according to claim 1, wherein the steps of: in the step 3 catalytic decomposition, the condensed liquid after adsorption is subjected to heat exchange to 100-120 ℃ and stays for 3 hours, so that the content of formal and macromolecules is reduced to 1%.
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| CN115806473B true CN115806473B (en) | 2023-09-12 |
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB799182A (en) * | 1956-04-23 | 1958-08-06 | Hercules Powder Co Ltd | Improvements in or relating to purification of pentaerythritol |
| US3066171A (en) * | 1958-11-10 | 1962-11-27 | Canadian Chemical Company Ltd | Purification of crude pentaerythritol |
| GB936083A (en) * | 1958-11-10 | 1963-09-04 | Canadian Chemical Company Ltd | Purification of pentaerythritol |
| US4329519A (en) * | 1979-07-26 | 1982-05-11 | Degussa Aktiengesellschaft | Process for the purification of pentaerythritol |
| CN105111047A (en) * | 2015-08-28 | 2015-12-02 | 安徽金禾实业股份有限公司 | Production method of Grade-99 pentaerythritol |
| CN109503325A (en) * | 2018-12-10 | 2019-03-22 | 安徽金禾实业股份有限公司 | A kind of method that pentaerythrite reduces coloration |
| CN114315517A (en) * | 2021-12-31 | 2022-04-12 | 赤峰瑞阳化工有限公司 | Production method of low-energy-consumption 98-grade pentaerythritol |
| CN115231990A (en) * | 2022-08-01 | 2022-10-25 | 重庆云天化天聚新材料有限公司 | Preparation method of high-purity dipentaerythritol |
-
2022
- 2022-12-08 CN CN202211570540.4A patent/CN115806473B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB799182A (en) * | 1956-04-23 | 1958-08-06 | Hercules Powder Co Ltd | Improvements in or relating to purification of pentaerythritol |
| US3066171A (en) * | 1958-11-10 | 1962-11-27 | Canadian Chemical Company Ltd | Purification of crude pentaerythritol |
| GB936083A (en) * | 1958-11-10 | 1963-09-04 | Canadian Chemical Company Ltd | Purification of pentaerythritol |
| US4329519A (en) * | 1979-07-26 | 1982-05-11 | Degussa Aktiengesellschaft | Process for the purification of pentaerythritol |
| CN105111047A (en) * | 2015-08-28 | 2015-12-02 | 安徽金禾实业股份有限公司 | Production method of Grade-99 pentaerythritol |
| CN109503325A (en) * | 2018-12-10 | 2019-03-22 | 安徽金禾实业股份有限公司 | A kind of method that pentaerythrite reduces coloration |
| CN114315517A (en) * | 2021-12-31 | 2022-04-12 | 赤峰瑞阳化工有限公司 | Production method of low-energy-consumption 98-grade pentaerythritol |
| CN115231990A (en) * | 2022-08-01 | 2022-10-25 | 重庆云天化天聚新材料有限公司 | Preparation method of high-purity dipentaerythritol |
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