A method for capturing methyl ethyl ketone by using imidazole ionic liquid in N2 environment

Abstract

The present application relates to a kind of methods for capturing ketone volatile organic compounds in N2 environment using imidazole ionic liquid.The method uses COSMO-RS model to screen ionic liquid absorbent, initially selects 1-octyl-3-methyl imidazole hexafluorophosphate as absorbent in solubility, selectivity, cost advantage, and then through absorption experiment, it is proved that the mass fraction of two kinds of ketone volatile organic compounds after absorption is less than 0.02%, and the purity of recycled ionic liquid absorbent is greater than 99.9%.Absorption-regeneration cycle experiment shows that the ionic liquid has good cycle stability and repeatable performance.The present application has high absorption efficiency, good regeneration performance, green and environmentally friendly operation process, can realize the efficient capture and resource recovery of ketone volatile organic compounds, and has good industrial application.

Description

Technical Field

[0001] This invention belongs to the field of gas absorption and chemical separation technology, specifically relating to a method for capturing methyl ethyl ketone using imidazole ionic liquids in an N2 environment. Background Technology

[0002] With the rapid development of industries such as coatings, inks, adhesives, electronic cleaning, and fine chemicals, the emission of volatile organic compounds (VOCs) continues to increase. Methyl ethyl ketone (MEK), a common organic solvent in coating production and use, is characterized by high volatility, large emissions, and a wide diffusion range. It is not only a significant precursor to photochemical smog and ozone pollution, but long-term exposure may also have adverse effects on the human respiratory and nervous systems. With the continuous advancement of my country's "dual-carbon" strategy and the requirements for comprehensive VOC management, developing efficient, green, and recyclable MEK capture and recovery technologies has become an important research direction in the fields of environmental governance and resource recycling.

[0003] Currently, volatile organic compound (VOC) treatment technologies mainly include combustion, adsorption, condensation, membrane separation, and absorption. Combustion can completely remove VOCs, but it suffers from high energy consumption, high operating costs, and large carbon dioxide emissions. Adsorption is mature and simple to operate, but the adsorbent is prone to saturation, resulting in high regeneration costs. Condensation is suitable for recovering high-concentration VOCs, but its effectiveness in treating low-concentration waste gas is limited. Membrane separation features compact equipment and low energy consumption, but the membrane material is easily fouled and separation selectivity is limited. In contrast, absorption offers advantages such as simple equipment, mild operating conditions, suitability for continuous operation, and the ability to achieve resource recovery of VOCs, making it a promising area for industrial waste gas treatment.

[0004] Existing absorption processes mostly use organic solvents as the absorption medium. However, while traditional organic absorbents have high solubility, they generally suffer from high volatility, flammability, explosiveness, high risk of secondary pollution, and poor recyclability. CN101062900B reports a method for absorbing the products of the ammonia oxidation reaction of m-xylene using the organic absorbent aniline. This method has the advantage of low production cost, and the resulting isophthalonitrile can significantly reduce the rate of condensation polymerization during hydrogenation, thereby extending the service life of the hydrogenation catalyst. However, the absorbent aniline used in the above method has certain toxicity and environmental risks, and as a traditional organic absorbent, it may still suffer from volatilization losses and secondary pollution. CN110152453B reports a method for capturing acidic gases in a gas mixture using solvent absorption, with the absorbent being chemical absorption solvents such as organic amines and inorganic salts. However, absorbents typically suffer from volatilization losses, corrosivity, high regeneration energy consumption, and the generation of degradation byproducts, which may increase subsequent treatment costs and environmental risks. Currently, commonly used absorbents are traditional organic absorbents, which generally suffer from problems such as high volatilization losses, flammability and explosiveness, high risk of secondary pollution, and poor recyclability. Furthermore, their selectivity for different volatile organic solvent components is limited, making it difficult to simultaneously achieve high absorption capacity and high separation efficiency. Therefore, developing an ionic liquid absorption system suitable for capturing methyl ethyl ketone, and systematically studying its absorption performance, molecular interaction mechanism, mass transfer enhancement strategies, and recycling characteristics, is of significant theoretical and practical value for improving the treatment efficiency of methyl ethyl ketone, reducing operating costs, and promoting the development of green and low-carbon waste gas treatment technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a method for capturing methyl ethyl ketone in an N2 environment using imidazole ionic liquids. By using imidazole ionic liquids with high absorption efficiency and good thermal stability as absorbents, selective absorption of methyl ethyl ketone in an N2 environment is achieved, thereby improving the problems of insufficient separation performance, absorbent loss and environmental risks in existing absorption systems.

[0006] Technical solution

[0007] This invention addresses the problem of difficult recovery of methyl ethyl ketone in the coatings industry by proposing a method for selectively separating methyl ethyl ketone from an N2 environment. This method is mild, environmentally friendly, and achieves an absorption efficiency of up to 80% for methyl ethyl ketone.

[0008] The present invention is achieved through the following technical solution.

[0009] A method for capturing methyl ethyl ketone in an N2 environment using imidazole ionic liquids includes the following steps: (1) Remove moisture from 1-octyl-3-methylimidazolium hexafluorophosphate; the absorbent is mainly an imidazolium ionic liquid; wherein the imidazolium ionic liquid is dried in a vacuum drying oven at 333.15 K for 6 h; (2) Change the absorption conditions; wherein the specific conditions are the inlet flow rate of 1-octyl-3-methylimidazolium hexafluorophosphate; (3) 1-octyl-3-methylimidazolium hexafluorophosphate enters from the top of the tower, and methyl ethyl ketone enters from the bottom of the tower, with the two in countercurrent contact conditions; (4) Absorption-circulation experiment; 1-octyl-3-methylimidazolium hexafluorophosphate is released from the bottom of the tower and then placed in a vacuum drying oven for drying, and the dried ionic liquid is used to capture methyl ethyl ketone again to verify its absorption performance.

[0010] As a further optimization of the method for capturing methyl ethyl ketone in an N2 environment using imidazole ionic liquids of the present invention, it is considered to reduce the initial water content of the ionic liquid to 500 ppm.

[0011] As a further optimization of the method of capturing methyl ethyl ketone in an N2 environment using an imidazole ionic liquid, considering the influence of the ionic liquid inlet flow rate on the absorption efficiency, the inlet flow rate of the ionic liquid was determined to be 1000 mL / h.

[0012] As a further optimization of the method of capturing methyl ethyl ketone in an N2 environment using an imidazole ionic liquid, considering the cyclic regeneration performance of the absorbent, the temperature of the vacuum drying oven was determined to be 333.15 K and the time to be 6 h.

[0013] Beneficial effects

[0014] This invention utilizes imidazole ionic liquids as absorbents to achieve selective absorption of methyl ethyl ketone in an N2 environment. This method enables methyl ethyl ketone to preferentially dissolve in imidazole ionic liquids, achieving an absorption efficiency of up to 80%. It offers advantages such as high absorption efficiency, good phase separation performance, mild operating conditions, and a simple process flow. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the method for capturing methyl ethyl ketone in an N2 environment using an imidazole ionic liquid according to the present invention. Detailed Implementation Example 1

[0016] A method for capturing methyl ethyl ketone in an N2 environment using imidazole ionic liquids includes the following steps: 1-Octyl-3-methylimidazolium hexafluorophosphate was placed in a vacuum drying oven and dried at 333.15 K for 6 h to remove moisture from the ionic liquid. The 1-octyl-3-methylimidazolium hexafluorophosphate was then sprayed from the top of the absorption tower at a rate of 200 mL / h and countercurrently contacted with methyl ethyl ketone entering from the bottom of the tower. Absorption experiments were conducted at ambient temperature and pressure. Online analysis of the absorbed components was performed using gas chromatography-mass spectrometry, showing an absorption efficiency of 30.07% for methyl ethyl ketone, demonstrating high absorption efficiency. After the absorption experiment, the ionic liquid was discharged from the bottom of the tower and placed in a vacuum drying oven, dried at 333.15 K for 6 h. After 5 absorption cycles, the absorption efficiency of 1-octyl-3-methylimidazolium hexafluorophosphate for methyl ethyl ketone fluctuated by less than 2%, indicating good regeneration performance. Example 2

[0017] A method for capturing methyl ethyl ketone in an N2 environment using imidazole ionic liquids includes the following steps: 1-Octyl-3-methylimidazolium hexafluorophosphate was placed in a vacuum drying oven and dried at 333.15 K for 6 h to remove moisture from the ionic liquid. The 1-octyl-3-methylimidazolium hexafluorophosphate was then sprayed from the top of the absorption tower at a rate of 500 mL / h and countercurrently contacted with methyl ethyl ketone entering from the bottom of the tower. Absorption experiments were conducted at ambient temperature and pressure. Online analysis of the absorbed components using gas chromatography-mass spectrometry showed an absorption efficiency of 60.24% for methyl ethyl ketone, demonstrating high efficiency. After the absorption experiment, the ionic liquid was discharged from the bottom of the tower and placed in a vacuum drying oven, dried at 333.15 K for 6 h. After 5 absorption cycles, the absorption efficiency of 1-octyl-3-methylimidazolium hexafluorophosphate for methyl ethyl ketone fluctuated by less than 2%, indicating good regeneration performance. Example 3

[0018] A method for capturing methyl ethyl ketone in an N2 environment using imidazole ionic liquids includes the following steps: 1-Octyl-3-methylimidazolium hexafluorophosphate was placed in a vacuum drying oven and dried at 333.15 K for 6 h to remove moisture from the ionic liquid. The 1-octyl-3-methylimidazolium hexafluorophosphate was then sprayed from the top of the absorption tower at a rate of 500 mL / h and countercurrently contacted with methyl ethyl ketone entering from the bottom of the tower. Absorption experiments were conducted at ambient temperature and pressure. Online analysis of the absorbed components using gas chromatography-mass spectrometry showed an absorption efficiency of 79.75% for methyl ethyl ketone, demonstrating high efficiency. After the absorption experiment, the ionic liquid was discharged from the bottom of the tower and placed in a vacuum drying oven, dried at 333.15 K for 6 h. After 5 absorption cycles, the absorption efficiency of 1-octyl-3-methylimidazolium hexafluorophosphate for methyl ethyl ketone fluctuated by less than 2%, indicating good regeneration performance.

Claims

1. A method for capturing methyl ethyl ketone using imidazole ionic liquids under N2 environment, characterized in that, Including the following steps: (1) Place the ionic liquid in a vacuum drying oven and dry it for 6 hours at 333.15K and -0.1MPa to ensure that the water content in the ionic liquid is reduced to below 500ppm; (2) A custom-designed absorber packed tower is used, with 1-octyl-3-methylimidazolium hexafluorophosphate entering from the top of the tower and acetone and methyl ethyl ketone entering from the bottom of the tower in countercurrent contact; (3) Adjust the inlet flow rate of 1-octyl-3-methylimidazolium hexafluorophosphate, wherein the inlet flow rates are 200 mL / h, 500 mL / h, 800 mL / h, and 1000 mL / h respectively; (4) Use gas chromatography to monitor the absorption efficiency of acetone and methyl ethyl ketone online.

2. The method for efficiently capturing ketone volatile organic compounds according to claim 1, characterized in that, The absorbent is an imidazole ionic liquid and has been vacuum dried to remove moisture.

3. The method for efficiently capturing ketone volatile organic compounds according to claim 1, characterized in that, The ionic liquid can selectively absorb acetone and methyl ethyl ketone and suppress the absorption of carrier gas N2.

4. The method for efficiently capturing ketone volatile organic compounds according to claim 1, characterized in that, The absorption conditions are normal temperature and pressure.

5. The method for efficiently capturing ketone volatile organic compounds according to claim 1, characterized in that, The inlet flow rates of the ionic liquid are 200 mL / h, 500 mL / h, 800 mL / h, and 1000 mL / h.

6. The method for efficiently capturing ketone volatile organic compounds according to claim 1, characterized in that, The analytical conditions were vacuum drying at 313.15 K for 6 hours.

7. The method for efficiently capturing ketone volatile organic compounds according to claim 1, characterized in that, The absorption-desorption cycle is repeated 5 times.

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