CN110372476B - Rectification process of 2, 2-dimethyl-1, 3-propylene glycol - Google Patents
Rectification process of 2, 2-dimethyl-1, 3-propylene glycol Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/88—Separation; Purification; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification of at least one compound
Abstract
The invention provides a rectification process of 2, 2-dimethyl-1, 3-propylene glycol, which comprises the following steps: 2, 2-dimethyl-1, 3-propanediol containing ester impurities is rectified and water is introduced during the rectification. The invention provides a rectification process of 2, 2-dimethyl-1, 3-propylene glycol, by introducing water into the 2, 2-dimethyl-1, 3-propylene glycol containing ester impurities in the rectification process, the ester impurities in the 2, 2-dimethyl-1, 3-propylene glycol are promoted to generate hydrolysis reaction, so that alkaline hydrolysis and extraction with an extracting agent are not required, the equipment investment of a device is reduced, the running cost of the device is reduced, but also has low pressure and high safety, can effectively reduce the content of ester impurities in the 2, 2-dimethyl-1, 3-propanediol, and the acid value of the final product can be reduced, the product quality is improved, and the mass percentage of the 2, 2-dimethyl-1, 3-propylene glycol in the final product is more than 99.2 percent, so that the improvement of the downstream product performance is facilitated.
Description
Technical Field
The invention relates to the field of chemical production, and particularly relates to a rectification process of 2, 2-dimethyl-1, 3-propylene glycol.
Background
2, 2-dimethyl-1, 3-propylene glycol is an important polyol organic chemical product, and is mainly used for producing unsaturated polyester resin, oil-free alkyd resin, polyester polyol, esters used for synthesizing lubricants, polyurethane foam plastics and elastomer plasticizers, additives of high-grade lubricating oil and other fine chemicals.
The production process of 2, 2-dimethyl-1, 3-propanediol is generally: organic tertiary amine such as trimethylamine, triethylamine and the like is used as a catalyst, formaldehyde and isobutyl aldehyde are used as raw materials to obtain hydroxyl tert-valeraldehyde through condensation, and the hydroxyl tert-valeraldehyde is hydrogenated to obtain the 2, 2-dimethyl-1, 3-propanediol. During the condensation reaction of formaldehyde and isobutyl aldehyde, a small amount of aldehyde raw materials are subjected to disproportionation reaction to generate a byproduct organic acid and alcohol, and the organic acid and the alcohol are further subjected to esterification reaction to generate ester substances and water, such as methyl formate, isobutyl isobutyrate, 2-dimethyl-1, 3-propanediol mono (di) formate, 2-dimethyl-1, 3-propanediol isobutyrate, 3-hydroxy-2, 2-dimethyl-3-hydroxy-2, 2-dimethylpropyl propionate and other ester impurities. The above ester impurities enter the refining unit along with the material. Some esters have boiling points which have large difference with the boiling point of the target product 2, 2-dimethyl-1, 3-propanediol or are azeotropic with water and can be easily separated and removed from a crude product system of the 2, 2-dimethyl-1, 3-propanediol, such as methyl formate, isobutyl isobutyrate, 3-hydroxy-2, 2-dimethyl-3-hydroxy-2, 2-dimethylpropyl propionate; however, some ester impurities have low relative volatility with the target 2, 2-dimethyl-1, 3-propanediol, such as 2, 2-dimethyl-1, 3-propanediol formate, 2-dimethyl-1, 3-propanediol isobutyrate, 2-dimethyl-1, 3-propanediol ester, which has a boiling point close to that of 2, 2-dimethyl-1, 3-propanediol, and the ester is difficult to separate from the crude 2, 2-dimethyl-1, 3-propanediol. Although some esters can be converted by hydrogenolysis to more easily separable alcohols, such as 2, 2-dimethyl-1, 3-propanediol mono (di) formate, by the action of a hydrogenation catalyst, hydrogenolysis does not ensure complete and complete performance and a small amount may remain. The existence of ester impurities not only affects the purity and yield of the final product, but also causes the consumption of raw materials for producing 2, 2-dimethyl-1, 3-propanediol to be increased and even affects the performance of downstream products due to the generation of the ester impurities.
In order to solve the problems, various refining processes of 2, 2-dimethyl-1, 3-propanediol are provided in the prior art. Chinese patent document CN101993351A discloses a method of hydrolyzing esters in the product by adding alkali after hydrogenation reaction, and then purifying by rectification under reduced pressure, but the process is complicated, and a large amount of water is introduced in the hydrolysis process by adding alkali, which results in increased energy consumption and increased cost in the rectification process, and also results in a large burden of sewage treatment; chinese patent document CN107311840A discloses a method of hydrogenation followed by extraction and then vacuum distillation purification, but because petroleum ether extraction is needed, the solvent consumption in the extraction process is large, the extraction efficiency is low, the production benefit is reduced, and secondary pollution is easily generated; chinese patent document CN103449970A discloses that esters can be decomposed into alcohols by hydrogenation, but the difficulty of hydrogenation reaction of the substances is different due to the difference of the transmission and diffusion properties of the substances in the catalyst channels, for example, the formate products can be hydrogenated and decomposed relatively more thoroughly, but the separation effect of hydrogenation and decomposition of esters such as isobutyric acid 2, 2-dimethyl-1, 3-propanediol ester, 3-hydroxy-2, 2-dimethyl-3-hydroxy-2, 2-dimethylpropyl propionate ester is limited, and the finished products also contain more ester impurities, which affects the quality and performance of the products.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defects of complex operation, high cost, low efficiency and high content of ester impurities of the 2, 2-dimethyl-1, 3-propanediol refining process in the prior art, thereby providing the 2, 2-dimethyl-1, 3-propanediol rectification process.
A rectification process of 2, 2-dimethyl-1, 3-propanediol comprises the following steps: 2, 2-dimethyl-1, 3-propanediol containing ester impurities is rectified and water is introduced during the rectification.
Further, the mass ratio of the water to the ester impurities is (0.2-3): 1.
Further, the rectification process is carried out in a rectification column.
Further, the water is introduced at the bottom or stripping section of the rectifying tower.
Further, the distance between the water introduction position and the feeding plate is 3-12 theoretical plates.
Furthermore, the distance between the water introduction position and the tower kettle is 0-12 theoretical plates.
Further, the water is liquid water and/or water vapor.
Further, the temperature of the water is 40-215 ℃.
Further, the rectification process is carried out for 1.0-4.0 hours under the conditions that the temperature of the tower kettle is 139-185 ℃ and the pressure is-0.1-0.06 MPa.
Further, the ester impurities comprise at least one of formate, isobutyrate, 2-dimethyl-3-hydroxypropionate.
Further comprises a step of removing heavy components in the 2, 2-dimethyl-1, 3-propylene glycol containing ester impurities by secondary rectification.
In the present invention, the equipment of the rectification process unit includes, but is not limited to, a rectification column, and all the rectification processes of 2, 2-dimethyl-1, 3-propanediol by using the equipment capable of realizing the rectification process are within the protection scope of the present application. For example, the structure can be one or a combination of more of the structure forms of a tank, a tower and the like. The equipment is made of a corrosion-resistant stainless steel material. Internals such as packing, distributors and heating tubes may be used in the apparatus. The filler can be regular filler or metal or nonmetal random filler.
The rectification feed is continuously fed to and discharged from the rectification process unit. The operation treatment is carried out by using a rectifying tower, the rectifying raw material is sent into the rectifying tower by using a pump or by using pressure difference, and the distribution of liquid in the packing in the tower can be enhanced by using internal parts such as a distributor or a spray head. After the gas-phase material at the top of the rectifying tower is condensed by the condenser, one part of the gas-phase material flows back to the inside of the rectifying tower, and the other part of the gas-phase material is sent out of the rectifying tower. One part of the liquid material in the tower bottom of the rectifying tower is heated by the heater and is partially vaporized, and then the liquid material returns to the tower bottom of the rectifying tower, and the other part of the liquid material is sent out of the rectifying tower. The temperature of a rectification process unit system is maintained by using a heater, a condenser and a heat preservation method, mass transfer and heat transfer of each component in the material occur in the rectification tower according to the gas-liquid equilibrium principle, and chemical reaction occurs in the rectification tower according to the chemical reaction equilibrium principle. In the packing of the rectifying tower, the hydrolysis reaction products of the ester impurities are separated according to the difference of relative volatility of each product.
The technical scheme of the invention has the following advantages:
1. the invention provides a rectification process of 2, 2-dimethyl-1, 3-propylene glycol, by introducing water into the 2, 2-dimethyl-1, 3-propylene glycol containing ester impurities in the rectification process, the ester impurities in the 2, 2-dimethyl-1, 3-propylene glycol are promoted to generate hydrolysis reaction, so that alkaline hydrolysis and extraction with an extracting agent are not required, the equipment investment of a device is reduced, the running cost of the device is reduced, but also has low pressure and high safety, can effectively reduce the content of ester impurities in the 2, 2-dimethyl-1, 3-propanediol, and the acid value of the final product can be reduced, the product quality is improved, and the mass percentage of the 2, 2-dimethyl-1, 3-propylene glycol in the final product is more than 99.2 percent, so that the improvement of the downstream product performance is facilitated.
2. The 2, 2-dimethyl-1, 3-propylene glycol rectification process further controls the introduction position of water in a tower kettle or a stripping section of a rectification tower, the 2, 2-dimethyl-1, 3-propanediol crude product before rectification contains water, and after entering a rectifying tower, water is directly evaporated and rises to the rectifying section to promote the hydrolysis of ester impurities in the rectifying section, while the stripping section and the tower kettle below the feeding plate almost have no water, therefore, extra water is introduced into the tower kettle or the stripping section, ester impurities below the feeding plate are directly contacted with the water to be hydrolyzed, the hydrolysis of the ester impurities in the 2, 2-dimethyl-1, 3-propylene glycol is more efficient and thorough, and the yield of the 2, 2-dimethyl-1, 3-propylene glycol is higher.
3. The 2, 2-dimethyl-1, 3-propylene glycol rectification process provided by the invention has the advantages that the crude 2, 2-dimethyl-1, 3-propylene glycol containing ester impurities is introduced into the rectification tower, water is introduced into the rectification tower in the rectification process to promote the hydrolysis reaction of the ester impurities in the crude 2, 2-dimethyl-1, 3-propylene glycol, light components with lower relative volatility than 2, 2-dimethyl-1, 3-propylene glycol in the crude 2, 2-dimethyl-1, 3-propylene glycol are separated firstly, then a tower bottom product is sent into the next rectification tower, heavy components in the crude 2, 2-dimethyl-1, 3-propylene glycol are removed through secondary rectification, the 2, 2-dimethyl-1 in the final product is further improved, 3-propylene glycol, and improves the product quality.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The rectification process of the following embodiment of the application is carried out in a rectification tower under a reduced pressure condition, a heater is used at the lower part of the rectification tower to heat a liquid-phase material to partially vaporize the liquid-phase material, a condenser is used at the top of the rectification tower to condense a gas-phase material, part of the condensed material at the top of the rectification tower is returned to the rectification tower as reflux, and part of the condensed material is sent out of the rectification tower as a product to be collected. The rectifying tower is provided with a tower plate or a filler, a distributor and other devices.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
The 2, 2-dimethyl-1, 3-propanediol crude product in the embodiment of the invention is obtained by taking formaldehyde and isobutyl aldehyde as raw materials, carrying out aldol condensation reaction to obtain a condensation product, evaporating the condensation product to recover unreacted raw materials, and then carrying out hydrogenation reaction, wherein the 2, 2-dimethyl-1, 3-propanediol crude product contains ester impurities. The 2, 2-dimethyl-1, 3-propanediol containing ester impurities of the invention includes but is not limited to the crude 2, 2-dimethyl-1, 3-propanediol, and can also be a 2, 2-dimethyl-1, 3-propanediol product still containing ester impurities after further concentrating or refining the crude 2, 2-dimethyl-1, 3-propanediol.
Example 1
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding 2, 2-dimethyl-1, 3-propanediol crude products into a rectification tower at the speed of 1000 kg/h, continuously introducing water with the temperature of 40 ℃ into the rectification tower at the speed of 3.3 kg/h, wherein the mass ratio of the introduced water to ester impurities in the 2, 2-dimethyl-1, 3-propanediol crude products is 0.2:1, the introduction position of the water is in a stripping section of the rectification tower, the distance from a feed inlet is 3 theoretical plates, the distance from a tower bottom is 3 theoretical plates, carrying out reduced pressure distillation for 1 h under the conditions that the pressure is-0.08 MPa and the temperature of the tower bottom is 169 ℃, separating and removing light components and light components after hydrolysis of the ester impurities, feeding material effluents of the tower bottom into a next rectification tower to separate and remove heavy components to obtain the 2, 2-dimethyl-1, 3-propanediol end product.
Example 2
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing water with the temperature of 60 ℃ into the rectification tower at the speed of 20 kg/h, wherein the mass ratio of the introduced water to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 1.2:1, the water is introduced into a stripping section of the rectification tower at the position of 12 theoretical plates away from a feed inlet and 8 theoretical plates away from a tower bottom, carrying out reduced pressure distillation for 3 hours under the conditions of the pressure of-0.06 MPa and the temperature of the tower bottom of 185 ℃, separating and removing light components and light components after hydrolysis of the ester impurities, feeding the material effluent from the tower bottom into a next rectification tower to separate and remove heavy components to obtain the 2, 2-dimethyl-1, 3-propanediol end product.
Example 3
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing water with the temperature of 80 ℃ into the rectification tower at the speed of 41.8 kg/h, wherein the mass ratio of the introduced water to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 2.5:1, the water introduction position is at a stripping section of the rectification tower, the distance from a feed inlet is 12 theoretical plates, the distance from a tower bottom is 12 theoretical plates, carrying out reduced pressure distillation for 2 hours under the conditions that the pressure is-0.09 MPa and the temperature of the tower bottom is 157 ℃, separating and removing light components and light components after hydrolysis of the ester impurities, feeding the material effluent of the tower bottom into a next rectification tower, separating and removing heavy components, obtaining 2, 2-dimethyl-1, 3-propanediol end product.
Example 4
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing water with the temperature of 100 ℃ into the rectification tower at the speed of 8.4 kg/h, wherein the mass ratio of the introduced water to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 0.5:1, introducing the water into a stripping section of the rectification tower, introducing the water into a feed inlet, introducing 3 theoretical plates into a tower kettle, introducing 8 theoretical plates into the tower kettle, carrying out reduced pressure distillation at the pressure of-0.085 MPa and the temperature of the tower kettle of 164 ℃ for 4 h, separating and removing light components and light components after hydrolysis of the ester impurities, feeding the material effluent from the tower kettle into a next rectification tower to separate and remove heavy components to obtain 2, 2-dimethyl-1, 3-propanediol end product.
Example 5
A2, 2-dimethyl-1, 3-propylene glycol rectification process comprises the steps of continuously feeding a crude product of 2, 2-dimethyl-1, 3-propylene glycol into a rectification tower at a speed of 1000 kg/h, continuously introducing water with the temperature of 135 ℃ into the rectification tower at a speed of 33.4 kg/h, wherein the mass ratio of the introduced water to ester impurities in the crude product of 2, 2-dimethyl-1, 3-propylene glycol is 2:1, introducing the water into a tower kettle of the rectification tower, carrying out reduced pressure distillation for 2 hours at the pressure of-0.07 MPa and the temperature of the tower kettle of 178 ℃, separating and removing light components and light components after hydrolysis of the ester impurities, and feeding a material flow discharged from the tower kettle into a next rectification tower to separate and remove heavy components to obtain a final product of the 2, 2-dimethyl-1, 3-propylene glycol.
Example 6
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing a mixture of water and steam at the temperature of 150 ℃ into the rectification tower at the speed of 30.1 kg/h, wherein the mass ratio of the introduced mixture of water and steam to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 1.8:1, introducing the mixture into a stripping section of the rectification tower, separating and removing light components and hydrolyzed light components from a feed inlet and a tower bottom by 8 theoretical plates at the pressure of-0.1 MPa and the temperature of the tower bottom of 139 ℃ for 3 hours, feeding the effluent of the tower bottom into a next rectification tower to separate and remove heavy components, to obtain the final product of the 2, 2-dimethyl-1, 3-propanediol.
Example 7
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing water with the temperature of 175 ℃ into the rectification tower at the speed of 13.4 kg/h, wherein the mass ratio of the introduced water to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 0.8:1, introducing the water into a stripping section of the rectification tower at the position of 8 theoretical plates from a feed inlet, introducing the water into a tower kettle at the position of 3 theoretical plates from the tower kettle, carrying out reduced pressure distillation at the pressure of-0.095 MPa and the temperature of the tower kettle of 149 ℃ for 1 h, separating and removing light components and light components after hydrolysis of the ester impurities, feeding the material effluent from the tower kettle into a next rectification tower to separate and remove heavy components to obtain 2, 2-dimethyl-1, 3-propanediol end product.
Example 8
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing a mixture of water and steam at the temperature of 185 ℃ into the rectification tower at the speed of 50.1 kg/h, wherein the mass ratio of the introduced mixture of water and steam to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 3:1, introducing the mixture into a stripping section of the rectification tower at the position of 3 theoretical plates from a feed inlet and 12 theoretical plates from a tower bottom, carrying out reduced pressure distillation at the pressure of-0.065 MPa and the temperature of the tower bottom of 182 ℃ for 4 hours, separating and removing light components after hydrolysis of the light components and the ester impurities, feeding the effluent of the tower bottom into a next rectification tower to separate and remove heavy components, to obtain the final product of the 2, 2-dimethyl-1, 3-propanediol.
Example 9
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing steam with the temperature of 200 ℃ into the rectification tower at the speed of 16.7 kg/h, wherein the mass ratio of the introduced steam to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 1:1, the introduction position is at a stripping section of the rectification tower, the distance from a feed inlet is 8 theoretical plates, the distance from a tower bottom is 12 theoretical plates, carrying out reduced pressure distillation for 2 hours under the conditions that the pressure is-0.075 MPa and the temperature of the tower bottom is 174 ℃, separating and removing light components and light components after hydrolysis of the ester impurities, feeding the material flow discharged from the tower bottom into a next rectification tower, separating and removing heavy components, obtaining 2, 2-dimethyl-1, 3-propanediol end product.
Example 10
A2, 2-dimethyl-1, 3-propanediol rectification process comprises feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification column at a speed of 1000 kg/hr, continuously introducing steam with the temperature of 210 ℃ into the rectifying tower at the speed of 36.7 kg/h, wherein the mass ratio of the introduced steam to ester impurities in the crude product of the 2, 2-dimethyl-1, 3-propanediol is 2.2:1, the introducing position is at the tower bottom of the rectifying tower, distilling under reduced pressure at-0.098 MPa and tower bottom temperature of 143 deg.C for 3 hr, separating to remove light components and the light components after ester impurities are hydrolyzed, and sending the material effluent from the tower bottom into the next rectifying tower to separate and remove heavy components to obtain the final product of the 2, 2-dimethyl-1, 3-propylene glycol.
Example 11
A2, 2-dimethyl-1, 3-propanediol rectification process comprises the steps of continuously feeding crude 2, 2-dimethyl-1, 3-propanediol into a rectification tower at the speed of 1000 kg/h, continuously introducing water vapor with the temperature of 215 ℃ into the rectification tower at the speed of 25.1 kg/h, wherein the mass ratio of the introduced water vapor to ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol is 1.5:1, the introduction position is at a stripping section of the rectification tower, the distance from a feed inlet is 12 theoretical plates, the distance from a tower bottom is 3 theoretical plates, carrying out reduced pressure distillation under the conditions that the pressure is-0.092 MPa and the temperature of the tower bottom is 154 ℃ for 1 h, separating and removing light components and light components after hydrolysis of the ester impurities, feeding the material effluent of the tower bottom into a next rectification tower to separate and remove heavy components to obtain 2, 2-dimethyl-1, 3-propanediol end product.
Comparative example 1
The specific operation of the 2, 2-dimethyl-1, 3-propanediol rectification process is the same as that in example 1, except that no water is introduced into the rectification column during the rectification process.
Examples of the experiments
The content of 2, 2-dimethyl-1, 3-propanediol and ester impurities in the crude 2, 2-dimethyl-1, 3-propanediol and the final 2, 2-dimethyl-1, 3-propanediol obtained in examples 1 to 11 and comparative example 1 were measured by gas chromatography, and the acid value was measured by the method for measuring acid value described in chemical industry standard HG/T2309-2017, and the measurement results are shown in Table 1.
TABLE 12 examination of crude and final 2-dimethyl-1, 3-propanediol
As can be seen from the detection results in table 1, the 2, 2-dimethyl-1, 3-propanediol rectification process provided in examples 1 to 11 of the present application can make the mass content of 2, 2-dimethyl-1, 3-propanediol in the final product reach more than 99.2%, and reduce the mass content of ester impurities to 0.35% or less; no water is added in the reduced pressure distillation process, so that the mass content of the 2, 2-dimethyl-1, 3-propylene glycol in the final product is 99.10%, and the mass content of ester impurities is 0.52%. In addition, the acid value of the product is determined by using 0.01mol/L sodium hydroxide standard solution according to the acid-base neutralization principle. The sodium hydroxide standard solution is inevitably excessive in the process of measuring the acid value, the 2, 2-dimethyl-1, 3-propylene glycol product contains a small amount of ester impurities, the ester impurities are easy to generate hydrolysis reaction under alkaline conditions to generate corresponding acid and alcohol, the corresponding acid consumes the sodium hydroxide standard solution to cause the measured final acid value of the 2, 2-dimethyl-1, 3-propylene glycol to be relatively high, and the acid value of the 2, 2-dimethyl-1, 3-propylene glycol product is relatively low by adopting the 2, 2-dimethyl-1, 3-propylene glycol rectification process provided by the embodiment of the invention.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (7)
1. A2, 2-dimethyl-1, 3-propanediol rectification process is characterized by comprising the following steps: rectifying 2, 2-dimethyl-1, 3-propylene glycol containing ester impurities and introducing water in the rectifying process;
the mass ratio of the water to the ester impurities is (0.2-3) to 1;
the rectification process is carried out in a rectification tower;
the water is introduced into the bottom or stripping section of the rectifying tower.
2. The rectification process of 2, 2-dimethyl-1, 3-propanediol according to claim 1, wherein the water is introduced at a distance of 3 to 12 theoretical plates from the feed plate.
3. The rectification process of 2, 2-dimethyl-1, 3-propanediol according to claim 1, characterized in that the distance between the water introduction position and the tower bottom is 0-12 theoretical plates.
4. The rectification process of 2, 2-dimethyl-1, 3-propanediol according to any one of claims 1-3, wherein the rectification process is carried out by vacuum distillation at a column bottom temperature of 139-185 ℃ and a pressure of-0.1-0.06 MPa for 1.0-4.0 hours.
5. The rectification process of 2, 2-dimethyl-1, 3-propanediol according to any of claims 1-4, wherein the water is liquid water and/or steam.
6. The rectification process of 2, 2-dimethyl-1, 3-propanediol according to any of claims 1-5, wherein the temperature of the water is 40-215 ℃.
7. The rectification process of 2, 2-dimethyl-1, 3-propanediol according to any of claims 1-6, further comprising a step of secondary rectification to remove heavy components from the 2, 2-dimethyl-1, 3-propanediol containing ester impurities.
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| JPS4896508A (en) * | 1972-03-01 | 1973-12-10 | ||
| DE3638496A1 (en) * | 1986-11-11 | 1988-05-26 | Huels Chemische Werke Ag | METHOD FOR OBTAINING PURE 2,2-DIMETHYL-1,3-PROPANDIOL (NPG) |
| CN101255104B (en) * | 2007-02-28 | 2012-01-04 | 中国科学院大连化学物理研究所 | Method and device for preparing carboxylic acids by hydrolysis of polybasic carboxylic acid ester |
| RU2530027C2 (en) * | 2008-12-09 | 2014-10-10 | Басф Се | Method of producing polymethylols |
| CN109180428B (en) * | 2018-08-06 | 2020-06-05 | 吉林市道特化工科技有限责任公司 | Production process of 2, 2-dimethyl-1, 3-propylene glycol |
| CN110372476B (en) * | 2019-08-06 | 2021-03-23 | 北京合宜集通科技有限公司 | Rectification process of 2, 2-dimethyl-1, 3-propylene glycol |
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2019
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| WO2021022831A1 (en) | 2021-02-11 |
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