An amido-imidazole ionic liquid membrane and a preparation method and application thereof

Abstract

The application relates to an amido-imidazole ionic liquid membrane and a preparation method and application thereof. First, ionic liquid [Aemim][Lys] and polymeric ionic liquid P[Aevim][Lys] are synthesized, then the two or the polymeric ionic liquid is mixed with porous materials such as mesoporous aluminum oxide, MCM-41 molecular sieve, SBA-15 molecular sieve, NaY zeolite molecular sieve, graphene oxide and organic solvents to prepare a casting solution, and finally, a membrane material with a required thickness is prepared by using the casting solution. The method has the advantages of simple process, large-scale industrial production and the like, the prepared membrane material is uniform in thickness and good in surface morphology, and has a good application prospect in CO2 adsorption and separation.

Description

Technical Field

[0001] This invention relates to the field of functional materials and gas separation technology, specifically to an aminoimidazolium ionic liquid membrane, its preparation method, and its application. Background Technology

[0002] There are many technologies used for CO2 separation and recovery in chemical production, mainly including chemical absorption, pressure swing adsorption (PSA), and membrane separation. Each of these methods has certain limitations. Chemical absorption involves reacting a specific absorbent with CO2 at a certain temperature, followed by heating the absorbent to desorb CO2, thus obtaining high-purity CO2. Currently, amine-based chemical absorption is the most widely used in the CO2 capture industry. While this type of solvent has good absorption efficiency and easily desorbs and releases high concentrations of CO2, amine absorbents also have disadvantages such as severe equipment corrosion, volatility, and high energy consumption. Adsorption methods utilize adsorbents with selective adsorption properties to physically separate CO2. This method has advantages such as simple operation, easy control, and low cost, but it also has disadvantages such as poor adsorption capacity and weak selectivity, thus limiting its industrial application.

[0003] Membrane separation is a method of separating CO2 and other components in a gas mixture based on their different permeation rates through a membrane material. This method offers advantages such as simple equipment, low fixed investment, high operational flexibility, and environmental friendliness. Membrane separation is a rapidly developing technology in the field of gas separation; however, the permeate flux and selectivity of ordinary membranes for CO2 separation cannot exceed the "Robeson upper limit," meaning it is difficult to obtain membrane materials that simultaneously possess high selectivity and high permeability. Faced with various problems in CO2 separation technology, there is an urgent need to improve existing membranes and adsorption materials. Numerous research institutions and enterprises are dedicated to developing high-performance CO2 separation membranes and similar membrane materials to improve CO2 separation efficiency and promote the widespread industrial application of CO2 separation membranes.

[0004] The inventors' team previously developed an imidazole glycinate polymeric ionic liquid and applied it to adsorption separation and other fields (see CN113861321A for details). In subsequent research, the inventors discovered that while ionic liquids exhibit excellent CO2 absorption performance, single ionic liquids generally suffer from high cost and viscosity, failing to meet the demands of industrial production. If ionic liquids could be loaded onto solid materials, or if polymeric ionic liquids could be directly used as membrane materials to construct gas separation membranes, the advantages of both ionic liquids and membrane technologies could be leveraged while overcoming their shortcomings. Such materials and technologies undoubtedly have broad development prospects.

[0005] A search revealed very few reports on functional ionic liquid membranes. Only studies have documented the use of ionic liquids containing a single amine group for membrane preparation and the functionalization of molecular sieves, with related research showing a significant increase in CO2 separation performance after the addition of ionic liquids. Currently, there are few reports on functional ionic liquids containing two or more amine groups in their molecular structure, and no reports have been found on the direct use of polymeric ionic liquids to replace organic polymer membrane materials for CO2 separation. Summary of the Invention

[0006] One objective of this invention is to provide an aminoimidazolium ionic liquid membrane, comprising an ionic liquid [Aemim][Lys], a polymeric ionic liquid P[Aevim][Lys], and a porous material, or a polymeric ionic liquid P[Aevim][Lys] and a porous material, wherein [Aemim][Lys], P[Aevim][Lys], and the porous material are uniformly dispersed in a membrane matrix.

[0007] Furthermore, the porous material is selected from at least one of the following materials: mesoporous alumina molecular sieve, MCM-41 molecular sieve, SBA-15 molecular sieve, NaY zeolite molecular sieve, and graphene oxide.

[0008] Furthermore, the mass ratio of [Aemim][Lys], P[Aevim][Lys], and porous material in the aminoimidazolium ionic liquid membrane is 1-3:6-10:1, or the mass ratio of P[Aevim][Lys] and porous material is 6-10:1.

[0009] The second objective of this invention is to provide a method for preparing the above-mentioned aminoimidazolium ionic liquid membrane, comprising the following steps: first, preparing the ionic liquid [Aemim][Lys] and the polymeric ionic liquid P[Aevim][Lys]; then, mixing [Aemim][Lys], P[Aevim][Lys], and a porous material, or mixing P[Aevim][Lys] and a porous material to form a casting solution; and finally, forming and drying the membrane.

[0010] Furthermore, the specific method for preparing the casting solution is as follows: Mix P[Aevim][Lys] and solvent in proportion, heat the resulting mixture to 110-180℃ and stir for more than 10 hours, then add [Aemim][Lys] and porous material and cool down to 70-90℃, and continue to stir magnetically for 12-24 hours.

[0011] Furthermore, the solvent used to prepare the casting solution is specifically N,N-dimethylformamide (DMF), and the film-forming method is at least one of coating film-forming, casting film-forming, and lifting film-forming.

[0012] The third objective of this invention is to utilize the above-mentioned aminoimidazolium ionic liquid membrane for adsorption and separation of CO2 from gases.

[0013] This invention combines the excellent CO2 transport and absorption properties of polyamine-functionalized ionic liquids. Based on low-toxicity imidazole-based ionic liquids, multiple amine functional groups are introduced to synthesize monomolecular and polymeric ionic liquids. Then, high-performance ionic liquid membranes are directly prepared using these two ionic liquids and porous materials as raw materials. Compared with existing similar technologies, the method of this invention has advantages such as simple process, high CO2 conversion efficiency, and the obtained membrane material has uniform thickness and good surface morphology, showing good application prospects in CO2 adsorption and separation. Attached Figure Description

[0014] Figure 1 This is a synthetic route diagram for the ionic liquid [Aemim][Lys] of the present invention;

[0015] Figure 2 This is a synthetic route diagram for the polymeric ionic liquid P[Aemim][Lys] of the present invention;

[0016] Figure 3 This is a comparison image of the ionic liquid composite membrane (a) of the present invention before drying (left image) and after drying (right image);

[0017] Figure 4 This is a comparison image of the ionic liquid composite membrane (b) of the present invention before drying (left image) and after drying (right image). Detailed Implementation

[0018] To enable those skilled in the art to fully understand the technical solution and beneficial effects of the present invention, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0019] The synthetic routes of the raw material ionic liquid [Aemim][Gly] and the polymeric ionic liquid P[Aevim][Lys] in this invention are as follows: Figure 1-2 As shown, similar Chinese invention patent CN113861321A can also be referenced.

[0020] Example 1

[0021] Weigh 5g of polymeric ionic liquid P[Aemim][Lys] into a 100mL round-bottom flask, add 20mL of DMF, and heat to 120℃ with stirring for 11h to completely dissolve. Add ionic liquid [Aemim][Gly] and NaY molecular sieve according to a specific ratio ([Aemim][Lys]:P[Aemim][Lys]:NaY molecular sieve mass ratio = 2:8:1). Cool the resulting mixture to 80℃ and continue magnetic stirring for 12h to obtain the casting solution. Take a small amount of the casting solution onto a film scraper, coat it into a film, and then vacuum dry to remove water, obtaining the following... Figure 3 The ionic liquid composite membrane shown is a.

[0022] Using an ionic liquid composite membrane (a) as raw material, CO2 in a mixture of Ar and CO2 gases was separated by differential pressure osmosis. The results showed that the membrane achieved a CO2 permeability of 80.55% and a selectivity of 90.27%.

[0023] Example 2

[0024] Weigh 4g of polymeric ionic liquid P[Aemim][Lys] into a 100mL round-bottom flask, add 15mL of DMF, and heat to 130℃ and stir for 12h to completely dissolve. Add MCM-41 molecular sieve according to a specific ratio (P[Aemim][Lys]:MCM-41 molecular sieve mass ratio = 8:1). Cool the resulting mixture to 80℃ and continue magnetic stirring for 24h to obtain the casting solution. Take a small amount of the casting solution onto a film scraper, coat it into a film, and vacuum dry for 24h to remove moisture, obtaining the desired film. Figure 4 The ionic liquid composite membrane b is shown.

[0025] The performance of the ionic liquid composite membrane b in separating CO2 from a N2 / CO2 mixture was evaluated using differential pressure osmosis. The results showed that the membrane material remained relatively stable when the pressure difference across the membrane reached 0.11 MPa, exhibiting neither rupture nor detachment. Furthermore, the test results indicated that the membrane achieved a CO2 permeability of 90.81% and a selectivity of 95.23%.

Claims

1. An amine-based imidazolium ionic liquid membrane capable of adsorptive separation of CO2, characterized in that: The composition of the ionic liquid membrane comprises ionic liquid [Aemim][Lys], polymeric ionic liquid P[Aevim][Lys] and porous material in a mass ratio of 1-3:6-10:1, or polymeric ionic liquid P[Aevim][Lys] and porous material in a mass ratio of 6-10:1, wherein the ionic liquid [Aemim][Lys], the polymeric ionic liquid P[Aevim][Lys] and the porous material are uniformly dispersed in the membrane matrix, and the porous material is selected from at least one of mesoporous alumina, MCM-41 molecular sieve, SBA-15 molecular sieve, NaY zeolite molecular sieve and graphene oxide.

2. The method of claim 1, wherein the amine-based imidazolium ionic liquid membrane is prepared by the steps of: The method comprises the following steps: first, preparing ionic liquid [Aemim][Lys] and polymeric ionic liquid P[Aevim][Lys], then mixing [Aemim][Lys], P[Aevim][Lys] and porous material or P[Aevim][Lys] and porous material to prepare a casting solution, and finally forming a film and drying.

3. The production method according to claim 2, characterized by The preparation method of the casting solution is as follows: mixing P[Aevim][Lys] and a solvent in a certain proportion, heating the obtained mixture to 110-180°C and stirring for more than 10h, then adding [Aemim][Lys] and porous material and cooling to 70-90°C for further magnetic stirring for 12-24h.

4. The production method according to claim 3, characterized by: The solvent used for preparing the casting solution is specifically N,N-dimethylformamide, and the film forming method is at least one of coating, casting and pulling.

5. Use of the amine-based imidazole ionic liquid membrane of claim 1 in adsorbing and separating CO2 from gas.

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