A separation method and a separation system for separating a methyl methacrylate and methanol azeotrope

Abstract

This invention relates to the field of chemical substance separation and purification technology, and discloses a separation method and system for separating an azeotropic system of methyl methacrylate and methanol. The method includes: using quaternary ammonium acetate and / or quaternary ammonium phenolate ionic liquid as an extractant, adding it to a mixture of methyl methacrylate and methanol for separation and purification. The ionic liquid, when used as an extractant to separate methyl methacrylate and methanol, has the following advantages: it does not form an azeotropic mixture with either component; it has a high boiling point, is not easily volatile, has good thermal stability, is easy to recover, and requires minimal replenishment; and in the separation of methyl methacrylate, only extractive distillation at atmospheric pressure is needed. Only one distillation column and two flash tanks are required to achieve the separation of methyl methacrylate and methanol, resulting in low equipment costs and low energy consumption. This separation method offers high product yield and quality, easy ionic liquid circulation, minimal replenishment, good polymerization inhibition effect, no introduction of new impurities, simple operation, and is suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of chemical substance separation and purification technology, and more specifically, to a separation method and system for separating a methyl methacrylate and methanol azeotropic system. Background Technology

[0002] Methyl methacrylate (MMA) is both an important organic chemical raw material and a significant organic chemical product directly applicable across various fields. As an organic chemical raw material, MMA is primarily used in the production of polymethyl methacrylate (PMMA). PMMA is a transparent organic material with excellent comprehensive properties, widely used in automotive, medical, communications, and construction industries. Furthermore, MMA can be used to manufacture acrylate copolymers for polyvinyl chloride (PVC) auxiliaries and terpolymers of MMA-butadiene-styrene, as well as as a second monomer in acrylonitrile fiber production, demonstrating a very broad application market and promising development prospects. In the C3 process of synthesizing MMA via acetone cyanohydrin, the product MMA forms an azeotrope with the raw material methanol at 64.4°C. The miscibility of MMA and methanol makes separation difficult using traditional methods. Moreover, MMA is an unsaturated compound that readily polymerizes at high temperatures, further increasing the difficulty of separation. Extractive distillation is a special distillation separation technique that separates components by adding an extractant to the distillation column. The extractant interacts differently with one or more substances in the azeotropic composition, altering the relative volatility of the original components. Polymerization inhibitors, through their electrophilic or nucleophilic abilities, can attract (or be attracted by) free radicals, inhibiting their activity and thus achieving polymerization inhibition.

[0003] The patent (CN201410637876) relates to a method for separating methyl methacrylate and methanol azeotropes using methyl acetate as an azeotropic agent. It employs an azeotropic distillation column, and in the application examples, the purity of the methyl methacrylate product can reach 99.8%.

[0004] The patent (CN202211316173) relates to a method and apparatus for separating methyl methacrylate and recovering the extractant using a dual extractant extraction and distillation process of n-hexane and water. The main components used are a formaldehyde separation tower, an MMA purification tower, an extractant recovery tower, and a methanol recovery tower. In the application examples, the purity of the methyl methacrylate product can reach 99.9%.

[0005] The literature (Gao Xiaoxin, Wang Tianyu, Chen Mengyuan, et al. Simulation and optimization of pressure swing distillation separation process of methyl methacrylate / methanol / water azeotropic system [J]. Natural Gas Chemical Industry (C1 Chemistry and Chemical Engineering), 2021, 46(02):122-127.) reported a method for separating methyl methacrylate and methanol using a pressure swing distillation tower and a high-pressure tower, wherein the purity of methyl methacrylate product was 99.99 wt% and the purity of methanol was 99.9 wt%.

[0006] The literature (GAO X, CHEN M, WANG T. Design and optimization for theseparation of a ternary methyl methacrylate-methanol-water mixture to save energy [J]. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020, 1-10.) provides a method for separating a methyl methacrylate / methanol / water azeotropic system using hexane and water dual-solvent extraction and distillation, which has high selectivity.

[0007] Patent (200410008736.X) relates to an ionic liquid polymerization inhibition method for preventing the polymerization of unsaturated compounds, which mentions an example of using [Bmim][PF6] to inhibit methyl methacrylate. In comparison with a blank control group and other polymerization inhibitors, methyl methacrylate using [Bmim][PF6] had a longer polymerization time and required a smaller amount.

[0008] The defects and shortcomings of the existing separation technologies mentioned above are as follows: First, methyl acetate and methanol are miscible and form a new azeotrope. Although this method can separate high-purity methyl methacrylate, the subsequent separation of the methyl acetate and methanol azeotropic system is difficult. The dual-solvent extraction and distillation method can obtain methyl methacrylate with a purity of 99.99%, but the purity of methanol cannot meet the requirements due to the close boiling points of n-hexane and methanol, and the large amount of n-hexane replenishment leads to high costs. In pressure swing distillation, the high-pressure tower pressure is 300 kPa, while methyl methacrylate, as a heat-sensitive material, is prone to polymerization at high temperatures, which can easily lead to low yield and equipment damage in actual production. Although [Bmim][PF6] can inhibit polymerization, it is difficult to implement in the process due to its immiscibility with methyl methacrylate.

[0009] Based on the above problems, how to disclose a separation method for the azeotropic system of methyl methacrylate and methanol that has good separation effect and can obtain both high-purity methyl methacrylate and high-purity methanol? Summary of the Invention

[0010] In view of this, the present invention proposes a separation method and separation system for separating methyl methacrylate and methanol azeotropic systems, aiming to solve the problems in the current technology of separating methyl methacrylate and methanol, such as the presence of methyl acetate and methanol in the extractant which are miscible and form new azeotropes, the large amount of n-hexane required for replenishment leading to high costs, and the problem that excessively high separation temperatures can easily cause methyl methacrylate to polymerize.

[0011] This invention proposes a separation method for an azeotropic system of methyl methacrylate and methanol, comprising the following steps:

[0012] A mixture of methyl methacrylate and methanol, along with an ionic liquid, is fed into a distillation column for separation. Methanol is collected from the top of the distillation column, while the mixture of ionic liquid and methyl methacrylate is collected from the bottom and enters a first flash tank. After separation in the first flash tank, methyl methacrylate is collected from the top of the first flash tank, and the ionic liquid is collected from the bottom of the first flash tank and enters a second flash tank. After separation in the second flash tank, the ionic liquid is recycled back to the distillation column from the bottom of the second flash tank for reuse. The mixture at the top of the second flash tank is reintroduced into the first flash tank for further separation.

[0013] The ionic liquid includes one or more of quaternary ammonium acetate and quaternary ammonium phenolate.

[0014] The ionic liquid includes one or more of methyltrioctyl acetate ammonium, tetrabutylphenol ammonium salt, and tetrabutylsalicylate ammonium.

[0015] Preferably, the ratio of the circulation rate of the ionic liquid to the mass flow rate of the mixture of methyl methacrylate and methanol is 1 to 1.5.

[0016] Preferably, the distillation column has 30 to 40 theoretical plates;

[0017] The feed location for the mixture of methyl methacrylate and methanol is the 25th to 35th tray.

[0018] Preferably, the feed temperature of the mixture of methyl methacrylate and methanol is 20~30°C.

[0019] Preferably, the pressure of the distillation column is 101.3 kPa;

[0020] The bottom temperature of the distillation column is 398.61 K, and the top temperature is 337.25 K.

[0021] Preferably, the operating pressure of the first flash tank is 10 kPa;

[0022] The temperature at the bottom of the first flash evaporator is 363.15 K, and the temperature at the top is 307.54 K.

[0023] Preferably, the operating pressure of the second flash tank is 10 kPa;

[0024] The bottom temperature of the second flash evaporator is 435.25 K, and the top temperature is 363.25 K.

[0025] Preferably, the amount of the ionic liquid added is 0.1 to 5 wt% of the mixture of methyl methacrylate and methanol.

[0026] The present invention also provides a separation system for separating a methyl methacrylate and methanol azeotropic system, comprising a distillation column, a first flash tank, and a second flash tank;

[0027] The bottom outlet of the distillation column is connected to the inlet of the first flash tank via a liquid pipeline. The bottom outlet of the first flash tank is connected to the inlet of the second flash tank via a conveying pipeline. The top outlet of the second flash tank is connected to the inlet of the first flash tank via a conveying pipeline. The bottom outlet of the second flash tank is connected to the top inlet of the distillation column.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The ionic liquid used in this invention has the following advantages when used as an extractant to separate methyl methacrylate and methanol: it does not form an azeotropic mixture with any of the components; it has a high boiling point, is not easily volatile, has good thermal stability, is easy to recover, and requires only a small amount of replenishment; and when separating methyl methacrylate, only extraction and distillation under normal pressure are needed.

[0030] The separation of methyl methacrylate and methanol requires only one distillation column and two flash tanks, resulting in low equipment costs and energy consumption. The ionic liquid used in this invention possesses excellent polymerization inhibition capabilities, eliminating the need for additional polymerization inhibitors or reducing their dosage, thus lowering costs. Furthermore, the separation method employed in this invention offers high product yield and quality, facilitates easy ionic liquid circulation with minimal replenishment, provides excellent polymerization inhibition, introduces no new impurities, is simple to operate, and is suitable for industrial application. Attached Figure Description

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0032] Figure 1 A structural diagram of a separation system for separating the azeotropic system of methyl methacrylate and methanol. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0034] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0037] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0038] This invention proposes a separation method for an azeotropic system of methyl methacrylate and methanol, comprising the following steps:

[0039] A mixture of methyl methacrylate and methanol, along with an ionic liquid, is fed into a distillation column for separation. Methanol is collected from the top of the distillation column, while the mixture of ionic liquid and methyl methacrylate is collected from the bottom and enters a first flash tank. After separation in the first flash tank, methyl methacrylate is collected from the top of the first flash tank, and the ionic liquid is collected from the bottom of the first flash tank and enters a second flash tank. After separation in the second flash tank, the ionic liquid is recycled back to the distillation column from the bottom of the second flash tank for reuse. The mixture at the top of the second flash tank is reintroduced into the first flash tank for further separation.

[0040] The ionic liquid includes one or more of quaternary ammonium acetate and quaternary ammonium phenolate.

[0041] The structural formula of the above-mentioned ionic liquid is shown in Formula I:

[0042] Formula I

[0043] R1, R2, R3, and R4 are selected from butyl, octyl, or hydrogen atoms. - H represents an anionic structure, such as carboxylate, phenol, and salicylate.

[0044] The ionic liquid includes ammonium methyltrioctyl acetate ([N... 8,8,8,1 [Ac]), Tetrabutylphenol ammonium salt ([N 4,4,4,4 [Ph]) and tetrabutylammonium salicylate ([N 4,4,4,4 One or more of [SA]).

[0045] Quaternary ammonium salt ionic liquids exhibit high solubility in alcohol-ester systems; anions are generally selected based on their separating and polymerization-inhibiting effects. Acetate ions are highly effective at breaking the azeotropic reaction in alcohol-ester systems, while anions with benzene ring structures, such as phenolic hydroxyl groups, have good polymerization-inhibiting effects.

[0046] The ionic liquids described in this invention were all purchased from Shanghai Moni Ionic Liquids Co., Ltd., and the relevant information is as follows:

[0047] Methyltrioctylacetic acid ammonium salt, product abbreviation: [O3MN]Ac, purity ≥ 98%, water content ≤ 1%;

[0048] Tetrabutylphenol ammonium salt, product abbreviation: [B4N]Ph, purity ≥ 98%, water content ≤ 1%;

[0049] Tetrabutylammonium salicylate, CAS No.: 22307-72-8, purity ≥ 98%, water content ≤ 1%.

[0050] Preferably, the ratio of the circulation rate of the ionic liquid to the mass flow rate of the mixture of methyl methacrylate and methanol is 1 to 1.5.

[0051] Preferably, the distillation column has 30 to 40 theoretical plates;

[0052] The feed location for the mixture of methyl methacrylate and methanol is the 25th to 35th tray.

[0053] Preferably, the feed temperature of the mixture of methyl methacrylate and methanol is 20~30°C.

[0054] Preferably, the pressure of the distillation column is 101.3 kPa;

[0055] The bottom temperature of the distillation column is 398.61 K, and the top temperature is 337.25 K.

[0056] Preferably, the operating pressure of the first flash tank is 10 kPa;

[0057] The temperature at the bottom of the first flash evaporator is 363.15 K, and the temperature at the top is 307.54 K.

[0058] Preferably, the operating pressure of the second flash tank is 10 kPa;

[0059] The bottom temperature of the second flash evaporator is 435.25 K, and the top temperature is 363.25 K.

[0060] Preferably, the amount of the ionic liquid added is 0.1 to 5 wt% of the mixture of methyl methacrylate and methanol.

[0061] The present invention also provides a separation system for separating a methyl methacrylate and methanol azeotropic system, comprising a distillation column, a first flash tank, and a second flash tank;

[0062] The bottom outlet of the distillation column is connected to the inlet of the first flash tank via a liquid pipeline. The bottom outlet of the first flash tank is connected to the inlet of the second flash tank via a conveying pipeline. The top outlet of the second flash tank is connected to the inlet of the first flash tank via a conveying pipeline. The bottom outlet of the second flash tank is connected to the top inlet of the distillation column. Example 1

[0063] Adopting such Figure 1 The separation system shown separates the azeotropic system of methyl methacrylate and methanol.

[0064] The initial azeotropic system contained 56.7 wt% methyl methacrylate and 43.3 wt% methanol.

[0065] The azeotropic system was introduced from the 25th tray of the distillation column. The ratio of the circulating flow rate of the ionic liquid (ammonium methyltrioctyl acetate) to the mass flow rate of the azeotropic system was 5.6. The theoretical number of trays in the distillation column was 30. The feed temperature of the azeotropic system was 25℃, the column pressure was 101.3 kPa, the bottom temperature of the distillation column was 398.61 K, and the top temperature was 337.25 K. After distillation, the methanol at the top of the distillation column has a mass fraction of 99.9 wt%. The mixture of methyl methacrylate and ionic liquid is collected from the bottom of the main column and enters the first flash tank. The pressure of the first flash tank is 10 kPa, the bottom temperature is 363.15 K, and the top temperature is 307.54 K. The methyl methacrylate at the top of the first flash tank has a mass fraction of 99.99 wt%. The liquid at the bottom of the first flash tank enters the second flash tank. The operating pressure of the second flash tank is 10 kPa, the bottom temperature is 435.25 K, and the top temperature is 363.25 K. After further separation in the second flash tank, the ionic liquid with a purity of 99.85 wt% is collected from the bottom of the second flash tank and recycled back to the main column for reuse. The mixture at the top containing methyl methacrylate and ionic liquid is returned to the first flash tank for further separation and purification.

[0066] 1. Further determination of the polymerization inhibition ability of the ionic liquid (methyltrioctyl acetate ammonium):

[0067] Methyl methacrylate was divided into three groups. Two groups were given 5 wt% ionic liquid and hydroquinone, respectively, while the other group was given no polymerization inhibitor as a blank control group.

[0068] The three groups of samples were incubated at 358.15 K for 6.5 hours, and the degree of polymerization of the three samples was determined. The degree of polymerization of the sample with added ionic liquid was 0.372 wt%, the degree of polymerization of the sample with added hydroquinone was 3.261 wt%, and the degree of polymerization of the blank group was 20.800 wt%.

[0069] 2. The effect of the amount of ionic liquid (methyltrioctyl acetate ammonium) added on the polymerization inhibition effect at a temperature of 423.15 K was determined:

[0070] Methyl methacrylate was divided into four groups, and 1 wt%, 5 wt%, 10 wt%, and 15 wt% ionic liquid were added to each group respectively.

[0071] The four groups of samples were incubated at 423.15K for 3 hours, and the degree of polymerization of the four samples was determined. The degree of polymerization of the four groups of samples were 0.59wt% (addition amount of 1wt%), 0.034wt% (addition amount of 5wt%), 0.032wt% (addition amount of 10wt%), and 0.028wt% (addition amount of 15wt%), respectively.

[0072] 3. The effect of the amount of ionic liquid (ammonium methyltrioctyl acetate) added on the polymerization inhibition effect was determined at 373.15 K:

[0073] Methyl methacrylate was divided into four groups, and 1 wt%, 5 wt%, 10 wt%, and 15 wt% ionic liquid were added to each group respectively.

[0074] The four groups of samples were incubated at 373.15 K for 3 hours, and the degree of polymerization of the four samples was determined. The degree of polymerization of the four groups of samples were 0.16 wt% (addition amount of 1 wt%), 0.02 wt% (addition amount of 5 wt%), 0.025 wt% (addition amount of 10 wt%), and 0.022 wt% (addition amount of 15 wt%), respectively. Example 2

[0075] Adopting such Figure 1 The separation system shown separates the azeotropic system of methyl methacrylate and methanol.

[0076] The initial azeotropic system contained 56.7 wt% methyl methacrylate and 43.3 wt% methanol.

[0077] The azeotropic system was introduced from the 25th tray of the distillation column. The ratio of the circulating flow rate of the ionic liquid (tetrabutylphenol ammonium salt) to the mass flow rate of the azeotropic system was 5.6. The theoretical number of trays in the distillation column was 30. The feed temperature of the azeotropic system was 25℃, the column pressure was 101.3 kPa, the bottom temperature of the distillation column was 398.61 K, and the top temperature was 337.25 K. After distillation, the methanol at the top of the distillation column has a mass fraction of 99.9 wt%. The mixture of methyl methacrylate and ionic liquid is collected from the bottom of the main column and enters the first flash tank. The pressure of the first flash tank is 10 kPa, the bottom temperature is 363.15 K, and the top temperature is 307.54 K. The methyl methacrylate at the top of the first flash tank has a mass fraction of 99.99 wt%. The liquid at the bottom of the first flash tank enters the second flash tank. The operating pressure of the second flash tank is 10 kPa, the bottom temperature is 435.25 K, and the top temperature is 363.25 K. After further separation in the second flash tank, the ionic liquid with a purity of 99.75 wt% is collected from the bottom of the second flash tank and recycled back to the main column for reuse. The mixture at the top containing methyl methacrylate and ionic liquid is returned to the first flash tank for further separation and purification.

[0078] 1. Further determination of the polymerization inhibition ability of the ionic liquid (tetrabutylphenol ammonium salt):

[0079] Methyl methacrylate was divided into three groups. Two groups were given 5 wt% ionic liquid and hydroquinone, respectively, while the other group was given no polymerization inhibitor as a blank control group.

[0080] The three groups of samples were incubated at 358.15 K for 6.5 hours, and the degree of polymerization of the three samples was determined. The degree of polymerization of the sample with added ionic liquid was 0.225 wt%, the degree of polymerization of the sample with added hydroquinone was 3.26 wt%, and the degree of polymerization of the blank group was 20.8 wt%.

[0081] 2. The effect of the amount of ionic liquid (tetrabutylphenol ammonium salt) added on the polymerization inhibition effect at a temperature of 423.15 K was determined:

[0082] Methyl methacrylate was divided into four groups, and 1 wt%, 5 wt%, 10 wt%, and 15 wt% ionic liquid were added to each group respectively.

[0083] The four groups of samples were incubated at 423.15K for 3 hours, and the degree of polymerization of the four samples was determined. The degree of polymerization of the four groups of samples were 0.281wt% (addition amount of 1wt%), 0.125wt% (addition amount of 5wt%), 0.062wt% (addition amount of 10wt%), and 0.026wt% (addition amount of 15wt%), respectively.

[0084] 3. The effect of the amount of ionic liquid (tetrabutylphenol ammonium salt) added on the polymerization inhibition effect was determined at 373.15 K:

[0085] Methyl methacrylate was divided into four groups, and 1 wt%, 5 wt%, 10 wt%, and 15 wt% ionic liquid were added to each group respectively.

[0086] The four groups of samples were incubated at 373.15K for 3 hours, and the degree of polymerization of the four samples was determined. The degree of polymerization of the four groups of samples were 0.152wt% (addition amount of 1wt%), 0.0188wt% (addition amount of 5wt%), 0.0171wt% (addition amount of 10wt%), and 0.015wt% (addition amount of 15wt%), respectively. Example 3

[0087] Adopting such Figure 1 The separation system shown separates the azeotropic system of methyl methacrylate and methanol.

[0088] The initial azeotropic system contained 56.7 wt% methyl methacrylate and 43.3 wt% methanol.

[0089] The azeotropic system was introduced from the 25th tray of the distillation column. The ratio of the circulating flow rate of the ionic liquid (tetrabutylammonium salicylate) to the mass flow rate of the azeotropic system was 5.6. The theoretical number of trays in the distillation column was 30. The feed temperature of the azeotropic system was 25℃, the column pressure was 101.3 kPa, the bottom temperature of the distillation column was 398.61 K, and the top temperature was 337.25 K. After distillation, the methanol at the top of the distillation column has a mass fraction of 99.9 wt%. The mixture of methyl methacrylate and ionic liquid is collected from the bottom of the main column and enters the first flash tank. The pressure of the first flash tank is 10 kPa, the bottom temperature is 363.15 K, and the top temperature is 307.54 K. The methyl methacrylate at the top of the first flash tank has a mass fraction of 99.99 wt%. The liquid at the bottom of the first flash tank enters the second flash tank. The operating pressure of the second flash tank is 10 kPa, the bottom temperature is 435.25 K, and the top temperature is 363.25 K. After further separation in the second flash tank, the ionic liquid with a purity of 99.85 wt% is collected from the bottom of the second flash tank and recycled back to the main column for reuse. The mixture at the top containing methyl methacrylate and ionic liquid is returned to the first flash tank for further separation and purification.

[0090] 1. Further determination of the polymerization inhibition ability of the ionic liquid (tetrabutylammonium salicylate):

[0091] Methyl methacrylate was divided into three groups. Two groups were given 5 wt% ionic liquid and hydroquinone, respectively, while the other group was given no polymerization inhibitor as a blank control group.

[0092] The three groups of samples were incubated at 358.15 K for 6.5 hours, and the degree of polymerization of the three samples was determined. The degree of polymerization of the sample with added ionic liquid was 0.292 wt%, the degree of polymerization of the sample with added hydroquinone was 3.26 wt%, and the degree of polymerization of the blank group was 20.8 wt%.

[0093] 2. The effect of the amount of ionic liquid (tetrabutylammonium salicylate) added on the polymerization inhibition effect at a temperature of 423.15 K was determined:

[0094] Methyl methacrylate was divided into four groups, and 1 wt%, 5 wt%, 10 wt%, and 15 wt% ionic liquid were added to each group respectively.

[0095] The four groups of samples were incubated at 423.15K for 3 hours, and the degree of polymerization of the four samples was determined. The degree of polymerization of the four groups of samples were 0.289wt% (addition amount of 1wt%), 0.135wt% (addition amount of 5wt%), 0.073wt% (addition amount of 10wt%), and 0.029wt% (addition amount of 15wt%), respectively.

[0096] 3. The effect of the amount of ionic liquid (tetrabutylammonium salicylate) added on the polymerization inhibition effect was determined at 373.15 K:

[0097] Methyl methacrylate was divided into four groups, and 1 wt%, 5 wt%, 10 wt%, and 15 wt% ionic liquid were added to each group respectively.

[0098] The four groups of samples were incubated at 373.15K for 3 hours, and the degree of polymerization of the four samples was determined. The degree of polymerization of the four groups of samples were 0.147wt% (addition amount of 1wt%), 0.019wt% (addition amount of 5wt%), 0.014wt% (addition amount of 10wt%), and 0.012wt% (addition amount of 15wt%), respectively.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for separating an azeotropic system of methyl methacrylate and methanol, characterized in that, Includes the following steps: A mixture of methyl methacrylate and methanol, along with an ionic liquid, is fed into a distillation column for separation. Methanol is collected from the top of the distillation column, while the mixture of ionic liquid and methyl methacrylate is collected from the bottom and enters a first flash tank. After separation in the first flash tank, methyl methacrylate is collected from the top of the first flash tank, and the ionic liquid is collected from the bottom of the first flash tank and enters a second flash tank. After separation in the second flash tank, the ionic liquid is recycled back to the distillation column from the bottom of the second flash tank for reuse. The mixture at the top of the second flash tank is reintroduced into the first flash tank for further separation. The ionic liquid includes one or more of quaternary ammonium acetate and quaternary ammonium phenolate.

2. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The ionic liquid includes one or more of methyltrioctyl acetate ammonium, tetrabutylphenol ammonium salt, and tetrabutylsalicylate ammonium.

3. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The circulation rate of the ionic liquid is 1 to 1.5 times the mass flow rate of the mixture of methyl methacrylate and methanol.

4. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The theoretical number of plates in the distillation column is 30 to 40. The feed location for the mixture of methyl methacrylate and methanol is the 25th to 35th tray.

5. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The feed temperature of the mixture of methyl methacrylate and methanol is 20~30℃.

6. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The pressure of the distillation column is 101.3 kPa; The bottom temperature of the distillation column is 398.61 K, and the top temperature is 337.25 K.

7. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The operating pressure of the first flash tank is 10 kPa; The temperature at the bottom of the first flash evaporator is 363.15 K, and the temperature at the top is 307.54 K.

8. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The operating pressure of the second flash tank is 10 kPa; The bottom temperature of the second flash evaporator is 435.25 K, and the top temperature is 363.25 K.

9. The separation method for separating the azeotropic system of methyl methacrylate and methanol according to claim 1, characterized in that, The amount of the ionic liquid added is 0.1 to 5 wt% of the mixture of methyl methacrylate and methanol.

10. A separation system for separating an azeotropic system of methyl methacrylate and methanol, characterized in that, Includes a distillation column, a first flash tank, and a second flash tank; The bottom outlet of the distillation column is connected to the inlet of the first flash tank via a liquid pipeline. The bottom outlet of the first flash tank is connected to the inlet of the second flash tank via a conveying pipeline. The top outlet of the second flash tank is connected to the inlet of the first flash tank via a conveying pipeline. The bottom outlet of the second flash tank is connected to the top inlet of the distillation column.

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