CN113845409B - Method for absorbing and refining methacrolein - Google Patents
Method for absorbing and refining methacrolein Download PDFInfo
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- CN113845409B CN113845409B CN202111207403.XA CN202111207403A CN113845409B CN 113845409 B CN113845409 B CN 113845409B CN 202111207403 A CN202111207403 A CN 202111207403A CN 113845409 B CN113845409 B CN 113845409B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/80—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
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- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C45/82—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
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Abstract
The invention belongs to the field of fine chemical industry, and relates to a method for absorbing and refining methacrolein. The invention adopts phenoxyethanol, diethylene glycol monophenyl ether or a mixture of the phenoxyethanol and the diethylene glycol monophenyl ether as an absorbent to absorb the methacrolein in the mixed gas in the oxidation step, and the methacrolein with the purity of more than 99 percent is obtained through standing, layering and rectifying. The process has the advantages of high absorption efficiency, high product purity, simple and nontoxic absorbent recycling, high safety of the whole process, simple operation, less absorbent loss, and suitability for industrial production.
Description
Technical Field
The invention belongs to the field of fine chemical industry, and particularly relates to an absorption and refining method of high-purity methacrolein.
Background
Methacrolein is an important chemical raw material, methacrylic acid can be obtained by further oxidation, and products such as methyl methacrylate, glycidyl methacrylate and the like are derived; the methylacrolein can be reduced to obtain methylallyl alcohol, which is an important raw material of a new generation of high-performance water reducer; in addition to this, methacrolein can also be used for copolymer and resin production.
At present, the method for producing the methacrolein is mainly an isobutene or tertiary butanol selective oxidation method, and the method is environment-friendly. However, the product obtained by the method is in a gas state, contains a large amount of diluent gas (such as nitrogen and the like), has low methacrolein content, and needs to be separated by an absorption method to obtain the methacrolein.
Patent CN 1817844a adopts water as an absorbent to absorb methacrolein, but because of poor miscibility of water and methacrolein, a large amount of water is required for absorption, the absorption efficiency is low, and the energy consumption is large.
The patent GP2110031 adopts methanol as an absorbent to improve the absorption efficiency, but the boiling point of the methanol is too low, and the methanol is easy to vaporize in the absorption process, so that a large amount of methanol is discharged along with tail gas, the methanol is lost more, and safety accidents are easy to cause.
Patent US3957880 uses ethanol and isopropanol as absorbents, which have a boiling point higher than that of methanol, but the presence of a large amount of diluent gas in the oxidation reaction brings away the absorbents to cause loss, and the intersolubility of the two alcohols with water is good, so that water in the reaction product is absorbed similarly to cause difficulty in separation.
The patent CN101844973a adopts alcohols with carbon number more than 4 as the absorbent, so that the loss of the absorbent is reduced to a certain extent, but the alcohols with larger carbon number basically have stronger pungent smell (such as butanol has pungent smell and can cause cough), so that the absorbed tail gas is discharged to seriously pollute the air, and the flash point of part of alcohols is lower, so that the use is unsafe.
CN103833537a uses alkanes having 6 to 8 carbon atoms as the absorbent, but these alkanes have a small difference in boiling point from methacrolein, are difficult to separate, and also cause a large amount of absorbent loss due to the low boiling point.
Patent CN101020625 adopts ionic liquid for absorption, but ionic liquid is expensive and difficult to use on a large scale.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for absorbing and refining high-purity methacrolein, so that the methacrolein has high absorptivity, is convenient to separate and is harmless.
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a method for absorbing and refining methacrolein, comprising the steps of:
s1, cooling mixed gas obtained after selective oxidation of isobutene or tertiary butanol, and then entering an absorption tower;
s2, using phenoxyethanol, diethylene glycol monophenyl ether or a mixture of the phenoxyethanol and the diethylene glycol monophenyl ether as an absorbent to carry out countercurrent absorption on the mixed gas;
s3, standing and layering an absorption liquid containing methacrolein, separating an upper water phase, and feeding heavy components into a rectifying tower;
s4, rectifying the heavy components to obtain high-purity methacrolein, and cooling the tower bottom material and returning the cooled tower bottom material to an absorption tower to be used as an absorbent for recycling.
As a preferred embodiment of the present invention, in S1, the gas obtained by selectively oxidizing isobutene or tert-butanol is cooled to 10 to 20℃and then fed into an absorption column. The gas temperature is too high, the absorption efficiency is reduced, the gas temperature is too low, and the energy consumption required for cooling is increased.
As a preferred embodiment of the invention, the absorbent selected in S2 is a mixed solvent of phenoxyethanol and diethylene glycol monophenyl ether with the mass ratio of 10:1-5:1. The freezing point of the phenoxyethanol is higher than that of the diethylene glycol monophenyl ether, but the water solubility of the phenoxyethanol is poorer than that of the diethylene glycol monophenyl ether, and the two are mixed for use, so that the problems of the freezing point and the water solubility can be well solved.
As a preferred embodiment of the present invention, the conditions for absorption in S2 are that the temperature of the bottom of the absorption column is 12 to 20℃and the temperature of the absorbent is 12 to 25 ℃. The temperature of the absorbent and the bottom of the absorption tower is too high, and the absorption efficiency is reduced; the temperature is too low, and the energy consumption is increased.
As a preferred embodiment of the invention, the mass ratio of gas to liquid in the S2 absorption process is selected to be 1:1-1:10, and more preferably 1:1.5-1:5. The larger the amount of the absorbent is, the better the absorption effect is, but the larger the energy consumption required by the subsequent rectification process is; the dosage of the absorbent is too small, and the absorption effect can not meet the requirement.
As a preferred embodiment of the present invention, the time for standing and delamination of the absorbent in S3 is 1 to 2 hours. The absorption liquid is subjected to standing delamination, part of water can be separated from the absorption liquid, and the layered water can be removed through liquid separation, so that the energy consumption required by the subsequent rectification is reduced, and the purity of the product is improved.
As a preferred embodiment of the present invention, the temperature of the bottom of the rectification column in S4 is 70 to 85℃and more preferably 75 to 78 ℃. The reflux ratio in the rectification process is 0.5-5, and more preferably, the reflux ratio is 0.5-1.5. Because the impurity content in the absorption liquid is low and the boiling point difference between the methacrolein and the absorbent is large, a smaller reflux ratio can be selected, and the production efficiency is improved; however, the reflux ratio is too small, and the purity of the product cannot meet the requirement.
The tail gas after absorption comprises 0.1-0.3 v/v% of methacrolein, 0.15-0.25 v/v% of isobutene, 89-90 v/v% of nitrogen, 0.1-0.2 v/v% of oxygen, 0.3-0.5 v/v% of carbon monoxide and carbon dioxide, 0.01-0.08 v/v% of methacrylic acid, trace acetone and the like.
Compared with the prior art, the invention has the beneficial effects that:
the method for absorbing and refining high-purity methacrolein provided by the invention takes a gas phase product obtained by selectively oxidizing isobutene or tertiary butanol as a raw material, and the methacrolein with the purity of more than 99% is obtained after absorption, standing delamination and rectification. The process has the advantages of good absorption effect, simple operation, less absorbent loss, low energy consumption, high product purity and high safety, and is suitable for industrial production.
In particular, the present invention has the following outstanding advantages over the prior art:
(1) Green safety: the absorbent used in the invention is one or a mixture of two of phenoxyethanol and diethylene glycol monophenyl ether, wherein the phenoxyethanol is commonly used in cosmetics, and has high safety level, so that the injury to operators in the whole operation process is small and the safety is high;
(2) The absorption effect is good: phenoxyethanol and diethylene glycol monophenyl ether are solvents with low viscosity, have good intersolubility with methacrolein, are used for absorbing the methacrolein, and have high absorption efficiency;
(3) The absorbent has small loss and convenient separation: the boiling points of phenoxyethanol and diethylene glycol phenyl ether are all over 240 ℃, and are not easy to volatilize, so that the loss is extremely small under the condition of higher gas flow rate; and because the boiling points (69 ℃) of the two are very different from that of the methacrolein, the rectification is convenient, the production efficiency is high, and the method is suitable for industrial production.
Detailed Description
The following further illustrates the aspects and effects of the present invention by way of specific examples.
Example 1
And cooling the gas-phase product after the oxidation of isobutene to 15 ℃, and then, entering a packed absorption tower. The absorption was carried out with phenoxyethanol (15 ℃) in an amount of 5 times the mass of the gas. The volume content of the gas before and after absorption is shown in table 1 (the data in the table are volume percent content).
The content of methacrolein in the heavy phase obtained by layering the absorption liquid obtained at the bottom of the absorption column after standing for 1 hour was 6.4%. In the rectification operation, under the condition that the bottom temperature is 75 ℃ and the reflux ratio is 0.5, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 2 (the data in the table are mass percent).
| Methacrolein (METAL) | Methacrylic acid | Acetic acid | Water and its preparation method | Others |
| 99.3 | 0.23 | 0.1 | 0.21 | 0.16 |
Example 2
And cooling the gas-phase product after the oxidation of isobutene to 15 ℃, and then, entering a packed absorption tower. The absorption was carried out with 5 times the mass of diethylene glycol monophenyl ether (15 ℃ C.). The volume content of the gas before and after absorption is shown in table 3 (the data in the table are volume percent content).
The absorption liquid obtained at the bottom of the absorption tower is kept stand for 2 hours, the content of methacrolein in the heavy phase obtained by layering is 6.1 percent, and the heavy phase is distilled. In the rectification operation, under the condition that the bottom temperature is 80 ℃ and the reflux ratio is 1.0, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 4 (the data in the table are mass percent).
| Methacrolein (METAL) | Methacrylic acid | Acetic acid | Water and its preparation method | Others |
| 99.43 | 0.14 | 0.06 | 0.20 | 0.18 |
Example 3
And cooling the gas-phase product after the oxidation of isobutene to 15 ℃, and then, entering a packed absorption tower. The mixture of phenoxyethanol and diethylene glycol monophenyl ether with the mass of 5 times of that of the gas is adopted for absorption, wherein the mass percentage content of the phenoxyethanol is 90 percent, and the temperature is 15 ℃. The volume content of the gas before and after absorption is shown in table 5 (the data in the table are volume percent content).
The content of methacrolein in the absorption liquid obtained at the bottom of the absorption tower is 6.3%, and the heavy phase is obtained by layering after standing for 1.5 hours and is removed for rectification. In the rectification operation, under the condition that the bottom temperature is 80 ℃ and the reflux ratio is 0.5, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 6 (the data in the table are mass percent).
| Methacrolein (METAL) | Methacrylic acid | Acetic acid | Water and its preparation method | Others |
| 99.23 | 0.22 | 0.09 | 0.23 | 0.30 |
Example 4
And cooling the gas-phase product after the oxidation of isobutene to 15 ℃, and then, entering a packed absorption tower. The absorption was carried out with phenoxyethanol (15 ℃) in an amount of 2 times the mass of the gas. The volume content of the gas before and after absorption is shown in table 7 (the data in the table are volume percent content).
The content of methacrolein in the heavy phase obtained by layering the absorption liquid obtained at the bottom of the absorption column after standing for 1 hour was 12.2%. In the rectification operation, under the condition that the bottom temperature is 75 ℃ and the reflux ratio is 1.5, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 8 (the data in the table are mass percent).
In this example, the amount of the absorbent was reduced, the absorption efficiency was lowered, and the concentration of methacrolein in the absorption liquid was increased.
Example 5
And cooling the gas-phase product after the oxidation of isobutene to 15 ℃, and then, entering a packed absorption tower. The absorption was carried out with phenoxyethanol (15 ℃) in an amount of 8 times the mass of the gas. The volume content of the gas before and after absorption is shown in table 9 (the data in the table are volume percent content).
The content of methacrolein in the heavy phase obtained by layering the absorption liquid obtained at the bottom of the absorption column after standing for 1.5 hours was 3.5%. In the rectification operation, under the condition that the bottom temperature is 75 ℃ and the reflux ratio is 1.0, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 10 (the data in the table are mass percent).
| Methacrolein (METAL) | Methacrylic acid | Acetic acid | Water and its preparation method | Others |
| 99.43 | 0.16 | 0.08 | 0.17 | 0.16 |
In this example, the absorption efficiency was improved by adding the absorbent, and the concentration of methacrolein in the absorption liquid was decreased.
Example 6
And cooling the gas-phase product after the oxidation of isobutene to 10 ℃, and then, entering a packed absorption tower. The absorption was carried out with 5 times the mass of diethylene glycol monophenyl ether (10 ℃ C.). The volume content of the gas before and after absorption is shown in table 11 (the data in the table are volume percent content).
The absorption liquid obtained at the bottom of the absorption tower is kept stand for 2 hours, the content of methacrolein in the heavy phase obtained by layering is 6.8%, and the heavy phase is distilled. In the rectification operation, under the condition that the bottom temperature is 80 ℃ and the reflux ratio is 1.0, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 12 (the data in the table are mass percent).
| Methacrolein (METAL) | Methacrylic acid | Acetic acid | Water and its preparation method | Others |
| 99.47 | 0.14 | 0.05 | 0.19 | 0.18 |
In this example, the absorption temperature was lowered, the absorption efficiency was improved, and the methacrolein content in the absorption liquid was increased.
Example 7
And cooling the gas-phase product after the oxidation of isobutene to 20 ℃, and then, entering a packed absorption tower. The absorption was carried out with 5 times the mass of diethylene glycol monophenyl ether (20 ℃ C.). The volume content of the gas before and after absorption is shown in table 13 (the data in the table are volume percent content).
The absorption liquid obtained at the bottom of the absorption tower is kept stand for 2 hours, the content of methacrolein in the heavy phase obtained by layering is 5.7%, and the heavy phase is distilled. In the rectification operation, under the condition that the bottom temperature is 80 ℃ and the reflux ratio is 1.0, the high-purity product methacrolein is obtained, and the composition of the methacrolein is shown in Table 14 (the data in the table are mass percent).
| Methacrolein (METAL) | Methacrylic acid | Acetic acid | Water and its preparation method | Others |
| 99.44 | 0.15 | 0.04 | 0.18 | 0.17 |
In this example, the temperature of the absorption liquid was increased, the absorption efficiency was decreased, and the concentration of methacrolein in the absorption liquid was decreased.
The invention adopts low-toxicity phenoxyethanol, diethylene glycol monophenyl ether or the mixture of the two as the absorbing agent of the methacrolein, and has high absorption efficiency; the two absorbents have high boiling points (the boiling point of phenoxyethanol is 247 ℃), and the loss in the absorption process is very small; the difference of boiling points with the methacrolein is large (the difference of boiling points with the methacrolein is more than 175 ℃), and the water is poor in intersolubility, so that the method is beneficial to rectification separation and is suitable for industrial production.
Claims (9)
1. A method for absorbing and refining methacrolein, comprising the steps of:
s1, cooling mixed gas obtained after selective oxidation of isobutene or tertiary butanol, and then entering an absorption tower;
s2, using phenoxyethanol, diethylene glycol monophenyl ether or a mixture of the phenoxyethanol and the diethylene glycol monophenyl ether as an absorbent to carry out countercurrent absorption on the mixed gas;
s3, standing and layering an absorption liquid containing methacrolein, separating an upper water phase, and feeding heavy components into a rectifying tower;
s4, rectifying the heavy components to obtain the methacrolein, and returning the tower bottom material to the absorption tower to be used as an absorbent for recycling.
2. The method for absorbing and purifying methacrolein according to claim 1, wherein: in S1, the content of methacrolein in the mixed gas after the selective oxidation of the isobutene or the tertiary butanol is 4-15 v/v%, and the mixed gas is cooled to 10-20 ℃ and then enters an absorption tower.
3. The method for absorbing and purifying methacrolein according to claim 1, wherein: the absorbent selected in the S2 is a mixed solvent of phenoxyethanol and diethylene glycol monophenyl ether with the mass ratio of 10:1-5:1.
4. The method for absorbing and purifying methacrolein according to claim 1, wherein: the absorption condition in S2 is that the temperature of the bottom of the absorption tower is 12-20 ℃, and the temperature of the absorbent is 12-25 ℃.
5. The method for absorbing and purifying methacrolein according to claim 4, wherein: the mass ratio of the gas to the liquid in the absorption process is 1:1.5-1:5.
6. The method for absorbing and purifying methacrolein according to claim 1, wherein: and S3, standing and layering for 1-2 h.
7. The method for absorbing and purifying methacrolein according to claim 1, wherein: the rectification condition in S4 is that the bottom temperature is 70-85 ℃.
8. The method for absorbing and purifying methacrolein according to claim 7, wherein: the reflux ratio in the rectification process is 0.5-5.
9. The method for absorbing and purifying methacrolein according to claim 1, wherein: the absorbent is recycled for at least 5 times, and then impurities such as methacrylic acid and the like are removed by distillation for continuous recycling.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101020625B (en) * | 2007-03-12 | 2010-05-19 | 中国科学院过程工程研究所 | Process of absorbing methyl acraldehyde with ionic liquid |
| CN101844973B (en) * | 2010-06-01 | 2013-07-03 | 上海华谊丙烯酸有限公司 | Method for absorbing and separating methacrolein |
| CN103833537B (en) * | 2014-02-28 | 2015-04-01 | 山东易达利化工有限公司 | Absorption and refining method for high-purity methylacrolein |
| CN110078603A (en) * | 2019-06-17 | 2019-08-02 | 淄博齐翔腾达化工股份有限公司 | The preparation method of purification and device of methacrolein |
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