Method for separating methyl acetate-methanol from thermo-sensitive polyion liquid

Abstract

The invention relates to a method for separating methyl acetate-methanol by using a thermo-sensitive polyion liquid, which is characterized in that the thermo-sensitive polyion liquid is used as an extraction agent, and the separation of a binary azeotropic mixture of methyl acetate and methanol by using the thermo-sensitive biimidazole polyion liquid P ([BIM-4C] Br) as the extraction agent is realized. P ([BIM-4C] Br) has excellent separation performance, has stronger acting force with methanol, and can bind methanol in a tower kettle, so that PILs (polyion liquid) has a better extraction effect compared with ILs. The influence of factors such as different temperatures, contents and O / A on the separation effect is researched, vapor-liquid phase equilibrium data of P ([BIM-4C] Br) is analyzed, the optimal separation condition is determined, and economic feasibility is achieved.

Description

[Technical field]

[0001] The invention belongs to the field of chemical separation and purification, and relates to a method for separating methyl acetate-methanol by using temperature-sensitive polyionic liquid. [Background technology]

[0002] Methyl acetate and methanol are both important basic chemical raw materials. Methyl acetate is miscible with most organic solvents and has a wide range of solubility. It can dissolve acrylic acid, vinyl, nitrocellulose, epoxy, polyurethane, polyester, phenolic resin, etc. It has a higher flash point and higher anti-whitening performance than acetone, and can better meet the coating, paint process formula and user requirements. Methanol is one of the basic organic raw materials and is mainly used to manufacture a variety of organic products such as methyl chloride, methylamine and dimethyl sulfate. It is also a raw material for pesticides (insecticides, acaricides) and medicines (sulfonamides, synmycin, etc.), and one of the raw materials for the synthesis of dimethyl terephthalate, methyl methacrylate and methyl acrylate. Azeotropes are produced during the production and use of methyl acetate and methanol, and cannot be separated by ordinary methods.

[0003] The efficient separation of azeotropes is an important research direction in the world's chemical industry, and high-end chemicals usually have very high purity requirements. How to achieve efficient separation and high purity is crucial to the development of my country's chemical industry. Chinese patent CN104478712B discloses a two-step extraction and distillation method for separating methyl acetate-methanol, using 1-hexyl-3-methylimidazole chloride with strong separation performance for coarse separation, and then using 1-ethyl-3-methylimidazole bromide with good solubility for fine division to obtain high-purity methyl acetate. The separation method reduces the pollution caused by the volatilization of the extractant, and can also be recycled and save costs.

[0004] Chinese patent CN106928027B discloses a method for extracting methanol from an acetaldehyde-methyl acetate-methanol-butanol-water mixture, which uses a continuous side-line distillation and extractive distillation integrated process to separate the acetaldehyde-methyl acetate-methanol-butanol-water mixture, thereby solving the problems of low methanol purity and yield. By simplifying the process and improving the separation efficiency, methanol with a content of 99.6% and a yield of more than 98.8% is obtained.

[0005] In order to further reduce costs and environmental risks, more economical and environmentally friendly extractants should be explored. Thermosensitive polyionic liquids are a type of temperature-responsive ionic liquid material that combines the properties of ionic liquids and thermosensitive polymers. They can regulate molecular structure and properties according to temperature changes, and are therefore used to separate and purify various compounds. Compared with ionic liquids, thermosensitive polyionic liquids have many advantages, including improved mechanical stability, chemical durability, temperature controllability, and processability. The development of thermosensitive polyionic liquid extractant construction strategies is of great significance for the separation of methyl acetate-methanol azeotropes and the low-cost recovery of extractants, and has broad prospects in the field of separation.

[0006] Therefore, providing a method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid has become an urgent problem to be solved in the art. [Summary of the invention]

[0007] [Technical issues to be solved]

[0008] The purpose of the present invention is to provide a method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid, to achieve separation of a binary azeotropic mixture of methyl acetate and methanol using a temperature-sensitive biimidazole polyionic liquid P([BIM-4C]Br) as an extractant, and to determine the feasibility of the extractant.

[0009] [Technical solution]

[0010] The present invention provides a method for separating a binary azeotropic mixture of methyl acetate and methanol using a temperature-sensitive polyionic liquid as an extractant, which mainly comprises the following steps:

[0011] (1) Synthesis of thermosensitive phosphate ionic liquid copolymers. Using RAFT polymerization, deoxygenated alcohol was used as solvent, AIBN was used as chain initiator, (((ethoxy)carbonyl)thio)acetic acid was used as chain transfer agent, and ionic liquid monomers were mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:2 to 10 to form phosphate ionic liquid copolymers.

[0012] (2) Prepare the solutions required for the experiment. The concentrations of [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol are both 10-15 wt%. The solution content is consistent with that in the phase equilibrium kettle, and the volume is about 50 mL. The gas-liquid phase equilibrium experiment is carried out.

[0013] (3) Ensure the stability and safety of the equipment. Turn on the heating button, set the heating kettle to heat slowly at a low voltage, and slowly adjust the voltage after the instrument stabilizes. After the solution in the equilibrium kettle boils, the temperature does not change within 20 minutes. At this time, the phase equilibrium is reached at this temperature, and the liquid phase temperature value is recorded.

[0014] (4) Analyze the effect of the ratio on the separation effect. Add different ratios of the extractant and the methyl acetate-methanol mixture into the gas-liquid phase reactor, and conduct multiple experiments with an O / A ratio of 1:1.7 to 5, observe the experimental phenomena, and take samples for measurement.

[0015] (5) Analyze the effect of temperature on separation effect. Adjust the temperature to 25-50°C. Increase the temperature gradually, observe the experimental phenomenon, maintain the temperature for a period of time, and take samples for measurement.

[0016] Preferably, the synthesized temperature-sensitive phosphate ionic liquid copolymer described in step (1) is used as an extractant.

[0017] Preferably, the ionic liquid monomer described in step (1) is mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:2 to 10.

[0018] Preferably, the concentrations of the [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol in step (2) are both 10-15 wt%.

[0019] Preferably, in step (4), the ratio of the extractant to the methyl acetate-methanol mixture O / A is 1:1.7-5.

[0020] Preferably, the temperature control range of the separation process in step (5) is 25 to 50°C.

Brief Description of the Drawings

[0021] Figure 1 This is the improved vapor-liquid equilibrium kettle diagram. [Specific implementation method]

[0022] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description in conjunction with the accompanying drawings and embodiments.

[0023] Embodiment 1:

[0024] (1) Synthesis of thermosensitive phosphate ionic liquid copolymers. Using RAFT polymerization, deoxygenated alcohol was used as solvent, AIBN was used as chain initiator, ((ethoxy)carbothiol)thio)acetic acid was used as chain transfer agent, and ionic liquid monomers were mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:2 to form phosphate ionic liquid copolymers.

[0025] (2) Prepare the solutions required for the experiment. The concentrations of [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol were both 10 wt%. The solution content was consistent with that in the phase equilibrium kettle, and the volume was about 55 m, and the gas-liquid phase equilibrium experiment was carried out.

[0026] (3) Ensure the stability and safety of the equipment. Turn on the heating button, set the heating kettle to heat slowly at a low voltage, and slowly adjust the voltage after the instrument stabilizes. After the solution in the equilibrium kettle boils, the temperature does not change within 20 minutes. At this time, the phase equilibrium is reached at this temperature, and the liquid phase temperature value is recorded.

[0027] (4) A certain ratio of extractant and methyl acetate-methanol mixture was added into the gas-liquid phase reactor, and multiple experiments were carried out with an O / A ratio of 1:1.7. The experimental phenomena were observed and samples were taken for determination.

[0028] (5) Adjust the temperature to 25°C, maintain it for a period of time, observe the experimental phenomena, and take samples for measurement.

[0029] (6) The gas chromatograph used 99.99% high-purity hydrogen as the carrier gas, the column temperature of the chromatograph was set to 160°C, the injector temperature was 160°C, and the detector temperature was 170°C. The sample composition was tested. According to the vapor-liquid equilibrium data, P([BIM-4C]Br) had better separation performance and stronger interaction with methanol. The internal standard method was used to obtain the linear relationship between the gas chromatographic peak area and the substance content, and the correlation coefficient R 2 All of them are greater than 0.999. The data fitting degree is high, and the correlation between peak area and mass is high.

[0030] Embodiment 2:

[0031] (1) Synthesis of thermosensitive phosphate ionic liquid copolymers. Using RAFT polymerization, deoxygenated alcohol was used as solvent, AIBN was used as chain initiator, ((ethoxy)carbomercapto)thio)acetic acid was used as chain transfer agent, and ionic liquid monomers were mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:6 to form phosphate ionic liquid copolymers.

[0032] (2) Prepare the solutions required for the experiment. The concentrations of [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol were both 12 wt%. The solution content was consistent with that in the phase equilibrium kettle, and the volume was about 55 m, and the gas-liquid phase equilibrium experiment was carried out.

[0033] (3) Ensure the stability and safety of the equipment. Turn on the heating button, set the heating kettle to heat slowly at a low voltage, and slowly adjust the voltage after the instrument stabilizes. After the solution in the equilibrium kettle boils, the temperature does not change within 20 minutes. At this time, the phase equilibrium is reached at this temperature, and the liquid phase temperature value is recorded.

[0034] (4) A certain proportion of the extractant and the alcohol ester mixture was added into the gas-liquid phase reactor, and multiple experiments were carried out with an O / A ratio of 1:3. The experimental phenomena were observed and samples were taken for determination.

[0035] (5) Adjust the temperature to 35°C, maintain it for a period of time, observe the experimental phenomena, and take samples for measurement.

[0036] (6) The gas chromatograph used 99.99% high-purity hydrogen as the carrier gas, the column temperature of the chromatograph was set to 160°C, the injector temperature was 160°C, and the detector temperature was 170°C. The sample composition was tested. According to the vapor-liquid equilibrium data, P([BIM-4C]Br) had better separation performance and stronger interaction with methanol. The internal standard method was used to obtain the linear relationship between the gas chromatographic peak area and the substance content, and the correlation coefficient R 2 All of them are greater than 0.999. The data fitting degree is high, and the correlation between peak area and mass is high.

[0037] Embodiment 3:

[0038] (1) Synthesis of thermosensitive phosphate ionic liquid copolymers. Using RAFT polymerization, deoxygenated alcohol was used as solvent, AIBN was used as chain initiator, ((ethoxy)carbothiol)thio)acetic acid was used as chain transfer agent, and ionic liquid monomers were mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:10 to form phosphate ionic liquid copolymers.

[0039] (2) Prepare the solutions required for the experiment. The concentrations of [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol were both 15 wt%. The solution content was consistent with that in the phase equilibrium kettle, and the volume was about 55 m, and the gas-liquid phase equilibrium experiment was carried out.

[0040] (3) Ensure the stability and safety of the equipment. Turn on the heating button, set the heating kettle to heat slowly at a low voltage, and slowly adjust the voltage after the instrument stabilizes. After the solution in the equilibrium kettle boils, the temperature does not change within 20 minutes. At this time, the phase equilibrium is reached at this temperature, and the liquid phase temperature value is recorded.

[0041] (4) A certain proportion of the extractant and the alcohol ester mixture was added into the gas-liquid phase reactor, and multiple experiments were carried out with an O / A ratio of 1:5. The experimental phenomena were observed and samples were taken for determination.

[0042] (5) Adjust the temperature to 50°C, maintain it for a period of time, observe the experimental phenomena, and take samples for measurement.

[0043] (6) The gas chromatograph used 99.99% high-purity hydrogen as the carrier gas, the column temperature of the chromatograph was set to 160°C, the injector temperature was 160°C, and the detector temperature was 170°C. The sample composition was tested. According to the vapor-liquid equilibrium data, P([BIM-4C]Br) had better separation performance and stronger interaction with methanol. The internal standard method was used to obtain the linear relationship between the gas chromatographic peak area and the substance content, and the correlation coefficient R 2 All of them are greater than 0.999. The data fitting degree is high, and the correlation between peak area and mass is high.

Claims

1. A method for separating methyl acetate and methanol using a temperature-sensitive polyionic liquid. Thermosensitive polyionic liquid was selected as the extractant to separate the methyl acetate-methanol azeotropic system at 101.3 kPa, and the effects of different temperatures, contents and O / A on the separation effect were studied. The following steps were included: (1) Synthesis of thermosensitive phosphate ionic liquid copolymers. Using RAFT polymerization, deoxygenated alcohol was used as solvent, AIBN was used as chain initiator, ((ethoxy)carbomercapto)thio)acetic acid was used as chain transfer agent, and ionic liquid monomers were mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:2 to 10 to form phosphate ionic liquid copolymers. (2) Prepare the solutions required for the experiment. The concentrations of [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol are both 10-15 wt%. The solution content is consistent with that in the phase equilibrium kettle, and the volume is about 50 mL. The gas-liquid phase equilibrium experiment is carried out. (3) Ensure the stability and safety of the equipment. Turn on the heating button, set the heating kettle to heat slowly at a low voltage, and slowly adjust the voltage after the instrument stabilizes. After the solution in the equilibrium kettle boils, the temperature does not change within 20 minutes. At this time, the phase equilibrium is reached at this temperature, and the liquid phase temperature value is recorded. (4) Analyze the effect of the ratio on the separation effect. Add different ratios of extractant and alcohol ester mixture into the gas-liquid phase reactor, conduct multiple experiments with an O / A ratio of 1:1.7 to 5, observe the experimental phenomena, and take samples for measurement. (5) Analyze the effect of temperature on separation effect. Adjust the temperature to 25-50°C. Increase the temperature gradually, observe the experimental phenomenon, maintain the temperature for a period of time, and take samples for measurement.

2. The method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid according to claim 1, characterized in that: The synthesized thermosensitive phosphate ionic liquid copolymer was used as the extractant.

3. The method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid according to claim 1, characterized in that: The ionic liquid monomer is mixed with N-isopropylacrylamide or acrylamide in a molar ratio of 1:2-10.

4. The method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid according to claim 1, characterized in that: The concentrations of [BIM-4C]Br monomer and P([BIM-4C]Br) in methyl acetate and methanol were both 10-15 wt%.

5. The method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid according to claim 1, characterized in that: The extractant and methyl acetate-methanol mixture O / A are selected to be 1:1.7-5.

6. The method for separating methyl acetate-methanol using a temperature-sensitive polyionic liquid according to claim 1, characterized in that: The temperature control range of the separation process is 25~50℃.

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