Functional organosilicon-coupled polyionic liquid heterostructure materials and their applications and methods in catalytic conversion of low-concentration carbon dioxide.

Abstract

This invention relates to a functional organosilicon coupled polyionic liquid heterostructure material and its applications and methods. This material has the advantages of novel structure, excellent catalytic performance, and recyclability. As a catalyst, it enables the synthesis of cyclic carbonates from epoxides and low-concentration carbon dioxide through a cycloaddition reaction. It can achieve highly selective catalytic conversion of low-concentration CO2 into cyclic carbonates under conditions without co-catalysts or solvents. Moreover, the catalyst and product can be separated simply by filtration after the reaction. It also has excellent versatility and recyclability, and has great application prospects.

Description

Technical Field

[0001] This invention belongs to the field of materials synthesis and catalysis technology. Specifically, it relates to a functional organosilicon coupled polyionic liquid porous heterostructure and its application and method in catalyzing the conversion of low-concentration carbon dioxide. Background Technology

[0002] Carbon dioxide (CO2) is a major greenhouse gas in the atmosphere. Human activities have led to a year-on-year increase in atmospheric CO2 levels, causing numerous ecological and environmental problems such as air pollution, global warming, and ocean acidification. At the same time, CO2 is also a naturally abundant, inexpensive, non-toxic, and renewable C1 resource. If CO2 could be directly converted into fuels or high-value-added chemicals, it would not only help achieve CO2 emission reduction goals but also reduce dependence on traditional resources such as coal, oil, and natural gas, which is of great significance from the perspective of environmental protection and sustainable chemistry. However, due to CO2's thermodynamic stability and kinetic inertness, the resource utilization of CO2 requires the development of effective catalytic technologies. Current literature reports the use of electrocatalysis, photocatalysis, or thermocatalysis to convert CO2 into various chemicals. Given the limitations of these technologies, only a small number of CO2 conversion processes have been industrialized, and statistics show that the amount of CO2 consumed accounts for only 0.36% of global emissions. Therefore, there is still considerable room for the utilization of this renewable resource.

[0003] The synthesis of cyclic carbonates from the reaction of CO2 with epoxides is one of the promising industrial-scale methods for the resource utilization of CO2, and has attracted widespread research. On the one hand, this reaction route is atom-economical and can effectively replace the traditional phosgene process, meeting the requirements of green chemistry development. On the other hand, cyclic carbonate products have excellent physicochemical properties (such as high boiling point, high polarity, and low volatility) and good biodegradability, and have wide applications in chemical, pharmaceutical, and polymer fields.

[0004] A series of catalytic systems have been reported in this field. Based on the different activation methods for epoxides, catalysts are mainly divided into two categories: transition metal catalysts and hydrogen bond donor (HBD) catalysts. Transition metal catalysts mainly include metal oxides, Salen metal complexes, metalloporphyrins, and metal-organic framework compounds, exhibiting excellent catalytic activity. However, homogeneous catalysts are difficult to separate from products, requiring vacuum distillation or extraction methods, which result in high energy consumption and the use of large amounts of volatile organic solvents. To overcome the challenge of catalyst separation, a series of inorganic-organic hybrid metal-organic framework (MOF) materials have been prepared using a solvothermal method. However, MOF materials suffer from drawbacks such as long synthesis cycles, high costs, and poor structural stability, limiting their large-scale industrial application. The HBD activation strategy can effectively replace the use of transition metals. A series of catalytic materials modified with HBD active centers have been reported, such as functionalized ionic liquids, porous organic polymers, nitrogen-doped carbon, supported / polymerized ionic liquids, and functionalized mesoporous organosilicones. Currently reported heterogeneous HBD-type catalysts mostly suffer from low catalytic activity and demanding reaction conditions when catalyzing CO2 cycloaddition reactions. Furthermore, from an economic and practical production perspective, designing and constructing novel heterogeneous catalytic materials that are easy to separate, highly active, and stable for the direct conversion and utilization of low-concentration CO2 in industrial waste gas is of greater significance.

[0005] Periodic mesoporous organosilicon (PMO) is a novel type of organic-inorganic hybrid ordered mesoporous nanocomposite material. It possesses a mesoporous structure of 2-30 nm and well-ordered pore walls. Bridging organic groups are widely and uniformly distributed on the pore walls; by altering these bridging groups, the surface properties of PMO can be changed, thereby altering its overall properties. The morphology of PMO can also be controlled through different synthetic methods; dodecahedral, spherical, membrane, three-dimensional, rotational, and rod-shaped PMOs have been synthesized. Due to its advantages such as tunable pore size, ordered pore structure, uniform distribution of organic groups, and good hydrothermal stability, it has attracted widespread attention from researchers both domestically and internationally. In recent years, PMO materials have been widely applied in various fields such as drug delivery, gene delivery, gas adsorption, water pollution treatment, chromatographic analysis, and catalysis. Li Gang et al. (Fuel, 2019, 244, 196-206) synthesized amorphous mesoporous titanium-silicon-based materials using polydiallyl dimethylammonium chloride (PDDA) as a mesoporous template and applied them to catalyze the reaction of CO2 with epoxides. The organic component (PDDA) can act as a Lewis base and titanium ions (Ti... 4+ ( ) acts as a Lewis acid, greatly improving the catalytic activity of the catalyst. However, most PMO catalysts require the addition of a co-catalyst, which increases the difficulty of separation. Therefore, developing a highly active catalytic system that avoids the introduction of a co-catalyst is particularly important.

[0006] Based on the above reports, providing a novel, recyclable, periodic mesoporous organosilicon and its coupled polyionic liquid preparation method, and enabling it to achieve efficient catalytic synthesis of cyclic carbonates from low-concentration CO2 under mild conditions, remains a significant challenge. Therefore, we propose this invention. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects in the prior art and provide a functional organosilicon coupled polyionic liquid heterostructure material that is easy to synthesize, highly active, easy to recycle and reusable, and provides its application as a catalyst for the cycloaddition reaction of low-concentration carbon dioxide with epoxides, and at the same time provides a method for catalyzing the reaction of low-concentration CO2 with epoxides to synthesize cyclic carbonates.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a functional organosilicon-coupled polyionic liquid heterostructure material, characterized in that it is prepared by a method comprising the following steps:

[0010] S1: Preparation of metalloporphyrin-based silicon source precursor

[0011] In anhydrous acetone, Zn-5,10,15,20-tetra(4-aminophenyl)porphyrin was reacted with propyltriethoxysilane isocyanate in a certain proportion. After the reaction was completed, the solvent was removed to obtain a metalloporphyrin-based silicon source precursor.

[0012] S2: Preparation of metalloporphyrin-based periodic mesoporous organosilicon

[0013] The metal porphyrin-based silicon source precursor obtained in step S1 is blended with tetraethyl silicate in the presence of a surfactant and then subjected to hydrolysis and copolymerization to generate metal porphyrin-based periodic mesoporous organosilicon.

[0014] S3: Synthesis of divinylimidazolium salt

[0015] 1-Vinylimidazole was reacted with 1,6-dibromohexane, 1,4-dibromobutane or 1,2-dibromoethane in tetrahydrofuran solvent under static hydrothermal conditions to obtain divinylimidazole salts with different carbon numbers.

[0016] S4: Synthesis of metalloporphyrin-functionalized organosilicon-coupled polyionic liquid porous heterostructure

[0017] The bisvinylimidazolium salt obtained in step S3 was subjected to in-situ polymerization on the metal porphyrin-based periodic mesoporous organosilicon framework obtained in step S2 under the action of the initiator 2,2'-azobisisobutyronitrile, to obtain a functional organosilicon coupled polyionic liquid heterostructure material.

[0018] As some preferred embodiments of the present invention, in step S1, the molar ratio of Zn-5,10,15,20-tetra(4-aminophenyl)porphyrin isocyanate propyltriethoxysilane is 1:4~4.5; in step S2, the molar ratio of the metalloporphyrin-based silicon source precursor to tetraethyl silicate silicon is 1:10~20; in step S3, the molar ratio of 1-vinylimidazolium to 1,6-dibromohexane, 1,4-dibromobutane, or 1,2-dibromoethane is 2~2.5:1; and in step S4, the mass ratio of the bisvinylimidazolium salt to the metalloporphyrin-based periodic mesoporous organosilicon is 1:1~1.2.

[0019] As some preferred embodiments of the present invention, the reaction temperature of step S1 is 50-80°C and the reaction time is 40-50h;

[0020] The reaction conditions for step S2 are as follows: first, stir at 40~50℃ for 20~24 h to form a uniform emulsion system; then transfer it to a hydrothermal reactor and statically heat at 100~150℃ for 90~100 h.

[0021] The reaction conditions for step S3 are as follows: first, stir at room temperature for 1-2 h, then transfer the mixture to a hydrothermal reactor and statically heat at 80-100℃ for 20-24 h;

[0022] The reaction conditions for step S4 are as follows: first, half of the 2,2-azobisisobutyronitrile is added to the mixture, heated to 40~60℃ and stirred for 20~24 h, then the remaining 2,2-azobisisobutyronitrile is dissolved in methanol and added to the mixture, and the mixture continues to react for 40~48 h.

[0023] In another aspect, the present invention provides the application of the above-mentioned functional organosilicon-coupled polyionic liquid heterostructure material in the catalytic conversion of low-concentration carbon dioxide.

[0024] In another aspect, the present invention provides a method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using the aforementioned functional organosilicon-coupled polyionic liquid heterostructure material. The method uses the functional organosilicon-coupled polyionic liquid heterostructure material as a catalyst to synthesize cyclic carbonates by cycloaddition reaction of epoxides and low-concentration carbon dioxide.

[0025] As some preferred embodiments of the present invention, the epoxide has the following structural formula:

[0026] .

[0027] As some preferred embodiments of the present invention, the amount of the functional organosilicon coupled polyionic liquid heterostructure material catalyst is 2wt% to 10wt% of the mass of the reaction system.

[0028] As some preferred embodiments of the present invention, the cycloaddition reaction temperature is 80 ~ 120°C, the reaction pressure is 0.5 ~ 1.5 MPa, and the time is 3 ~ 7 h.

[0029] As some preferred embodiments of the present invention, the functional organosilicon-coupled polyionic liquid heterostructure material is Zn-TPMO. 20 @PIL-C6.

[0030] In some preferred embodiments of the present invention, the low concentration of carbon dioxide is 10-15%.

[0031] The beneficial effects of adopting the above technical solution are as follows:

[0032] The functional organosilicon-coupled polyionic liquid heterostructure material provided by this invention possesses advantages such as novel structure, excellent catalytic performance, good selectivity, and recyclability. The raw materials for this material are readily available, the conditions are mild, the synthesis is highly efficient, and it has industrial applicability, enabling the direct conversion and utilization of low-concentration carbon dioxide in industrial applications.

[0033] The catalyst of this invention has a unique structure containing Lewis acid (Zn). 2+ Hydrogen bond donors (HBD) and nucleophiles (Br) - It can efficiently activate epoxides and inert carbon dioxide molecules, enabling the catalytic process to selectively convert low-concentration carbon dioxide into cyclic carbonates under solvent-free and catalyst-free conditions. After the reaction, the catalyst and product can be separated by filtration. It overcomes the shortcomings of the currently reported catalytic systems, such as low activity, poor stability, poor cycle performance, and dependence on catalysts that are not easy to separate, and has good potential for industrial application. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly described below.

[0035] Figure 1 This is a reaction flow diagram of the present invention;

[0036] Figure 2 This invention is [VImC6]Br,Zn-TPMO 20 and Zn-TPMO 20 @PIL-C6 infrared spectrum;

[0037] Figure 3 This invention is Zn-TPMO 20 and Zn-TPMO 20 @PIL-C6 small-angle XRD pattern;

[0038] Figure 4 These are transmission electron microscope (TEM) images of the porous heterostructure material of this invention, wherein (a) is Zn-TPMO. 20 (b) is Zn-TPMO 20 @PIL-C6.

[0039] Figure 5 The present invention comprises [VImC2]Br, [VImC4]Br, [VImC6]Br, and Zn-TPMO. 20 and Zn-TPMO 20 Thermogravimetric analysis spectrum of @PIL-C6. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the invention will be described clearly and completely below in conjunction with specific embodiments.

[0041] In this embodiment, the synthesis route of the functional organosilicon-coupled polyionic liquid heterostructure material is described in [link to embodiment]. Figure 1 .

[0042] Example 1: Preparation of metalloporphyrin-based silicon source precursor

[0043] Zn-5,10,15,20-tetra(4-aminophenyl)porphyrin was dissolved in 30 mL of anhydrous acetone. Propyltriethoxysilane isocyanate (SCA) was added at a molar ratio of 1:4-4.5 under a nitrogen atmosphere. The mixture was stirred at 60 °C for 48 h. After the reaction was complete, the acetone solvent was removed by rotary evaporation, and the residue was washed three times with n-hexane and dried overnight under vacuum to obtain a metalloporphyrin-based silicon precursor in 95% yield.

[0044] Example 2: Preparation of metalloporphyrin-based periodic mesoporous organosilicon

[0045] Zn-TPMO with different compositions was prepared by adjusting the molar ratio of metalloporphyrin-based silicon precursor and tetraethyl orthosilicate (TEOS) using a surfactant-templated co-condensation method. x ( x = 10, 15, 20).

[0046] Template CTAB (3.5 g, 9.6 mmol) was suspended in a solution of NH3·H2O (12 mL) and deionized water (164 mL) and stirred at 40 °C for 0.5 h. During stirring, a premixed solution of metalloporphyrin-based silicon source precursor (1.73 g, 1.0 mmol) and TEOS (16.7 g, 80 mmol) in ethanol (55 mL) with a silicon molar ratio of 1:20 was added dropwise. The mixture was stirred at 40 °C for 24 h to form a homogeneous emulsion system. It was then transferred to a hydrothermal reactor and statically heated at 120 °C for 96 h. After separation by filtration, CTAB was removed by Soxhlet extraction with ethanol-hydrochloric acid solution at 60 °C for 6 h, repeated three times to remove CTAB. Finally, Zn-TPMO was obtained by filtration and vacuum drying. 20 The yield was 86%.

[0047] In this way, by changing Si (金属卟啉基硅源前驱体) Si (TEOS) Zn-TPMO was prepared at molar ratios of 1:10 and 1:15. 10 and Zn-TPMO 15 The yields were 80% and 83%, respectively.

[0048] Example 3: Synthesis of divinylimidazolium salt

[0049] 1-Vinylimidazole (2.5 g, 26.6 mmol) and 1,6-dibromohexane (3.25 g, 13.3 mmol) were dissolved in 5 mL of tetrahydrofuran. After stirring at room temperature for 1 h, the mixture was transferred to a hydrothermal reactor and statically heated at 100 °C for 24 h. The crude product was washed with ethyl acetate (2 x 50 mL) and dried under vacuum to give product [VImC6]Br in 89% yield.

[0050] Similarly, replacing the reactants with 1,4-dibromobutane and 1,2-dibromoethane yields [VImC4]Br and [VImC2]Br, respectively, with yields of 76% and 86%.

[0051] Example 4: Synthesis of Metalloporphyrin-based Periodic Mesoporous Organosilicon Coupled Polyionic Liquid

[0052] Zn-TPMO 20Zn-TPMO (0.45 g) and [VImC6]Br (0.43 g, 1 mmol) were added to 20 mL of anhydrous methanol solution and stirred for 24 h under a nitrogen atmosphere at room temperature. 2,2-Azobisisobutyronitrile (0.054 g) was dissolved in 10 mL of methanol and added to the mixture. The mixture was then heated to 60 °C and stirred for 24 h. Another 0.054 g of 2,2-azobisisobutyronitrile (0.054 g) was dissolved in 10 mL of methanol and added to the mixture. The reaction continued for 48 h. After the reaction was complete, Zn-TPMO... 20 @PIL-C6 was washed three times with methanol and dried overnight at 80°C, with a yield of 89%. Under the same reaction conditions, the reactant was replaced with Zn-TPMO. 10 and Zn-TPMO 15 Zn-TPMO can then be obtained. 10 @PIL-C6 and Zn-TPMO 15 @PIL-C6, yields were 86% and 88%, respectively.

[0053] Under the same conditions, replacing the reactants with [VImC2]Br and [VImC4]Br will yield Zn-TPMO. 20 @PIL-C2 and Zn-TPMO 20 @PIL-C4, yields were 88% and 82%, respectively.

[0054] Example 5

[0055] Take the reactant epichlorohydrin and the catalyst Zn-TPMO prepared in Example 4. 20 @PIL-C6 was sequentially added to a 25 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, containing 17.2 mmol (1.6 g) of epichlorohydrin and Zn-TPMO. 20 @PIL-C60.1 g, accounting for 6 wt.% of the reactants; 10% CO2 gas was slowly introduced into the reactor to remove residual air; then, 10% CO2 gas was introduced to maintain a constant pressure of 1.0 MPa, and the reactor was heated to 110 ℃ in an oil bath for 4 hours; after the reaction was completed, the reactor was cooled to room temperature in an ice-water bath, and the product was quantitatively analyzed by gas chromatography-mass spectrometry. The yield of chloropropylene carbonate was 82%, and the selectivity was ≥99%.

[0056] Example 6

[0057] Take the reactant epichlorohydrin and the catalyst Zn-TPMO prepared in Example 4. 20 @PIL-C6 was sequentially added to a 25 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, containing 17.2 mmol (1.6 g) of epichlorohydrin and Zn-TPMO. 20@PIL-C60.14 g, accounting for 8 wt.% of the reactants; 10% CO2 gas was slowly introduced into the reactor to remove residual air; then, 10% CO2 gas was introduced to maintain a constant pressure of 2.0 MPa, and the reactor was heated to 90 ℃ in an oil bath for 4 hours; after the reaction was completed, the reactor was cooled to room temperature in an ice-water bath, and the product was quantitatively analyzed by gas chromatography-mass spectrometry. The yield of chloropropylene carbonate was 86%, and the selectivity was ≥99%.

[0058] Example 7

[0059] Take the reactant epichlorohydrin and the catalyst Zn-TPMO prepared in Example 4. 20 @PIL-C6 was sequentially added to a 25 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, containing 17.2 mmol (1.6 g) of epichlorohydrin and Zn-TPMO. 20 @PIL-C60.1 g, accounting for 6 wt.% of the reactants; 10% CO2 gas was slowly introduced into the reactor to remove residual air; then, 10% CO2 gas was introduced to maintain a constant pressure of 1.0 MPa, and the reactor was heated to 110 ℃ in an oil bath for 6 hours; after the reaction was completed, the reactor was cooled to room temperature in an ice-water bath, and the product was quantitatively analyzed by gas chromatography-mass spectrometry. The yield of chloropropylene carbonate was 96%, and the selectivity was ≥99%.

[0060] Example 8

[0061] Take the reactant epichlorohydrin and the catalyst Zn-TPMO prepared in Example 4. 20 @PIL-C6 was sequentially added to a 25 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, containing 17.2 mmol (1.6 g) of epichlorohydrin and Zn-TPMO. 20 @PIL-C60.07 g, accounting for 4 wt.% of the reactants; 10% CO2 gas was slowly introduced into the reactor to remove residual air; then, 10% CO2 gas was introduced to maintain a constant pressure of 2.0 MPa, and the reactor was heated to 100 ℃ in an oil bath for 6 hours; after the reaction was completed, the reactor was cooled to room temperature in an ice-water bath, and the product was quantitatively analyzed by gas chromatography-mass spectrometry. The yield of chloropropylene carbonate was 85%, and the selectivity was ≥99%.

[0062] Example 9

[0063] Take the reactant epichlorohydrin and the catalyst Zn-TPMO prepared in Example 4. 20 @PIL-C6 was sequentially added to a 25 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, containing 17.2 mmol (1.6 g) of epichlorohydrin and Zn-TPMO.20 @PIL-C60.14 g, accounting for 8 wt.% of the reactants; 10% CO2 gas was slowly introduced into the reactor to remove residual air; then, 10% CO2 gas was introduced to maintain a constant pressure of 0.5 MPa, and the reactor was heated to 80°C in an oil bath for 7 hours; after the reaction was completed, the reactor was cooled to room temperature in an ice-water bath, and the product was quantitatively analyzed by gas chromatography-mass spectrometry. The yield of chloropropylene carbonate was 79%, and the selectivity was ≥99%.

[0064] Example 10

[0065] Take the reactant epichlorohydrin and the catalyst Zn-TPMO prepared in Example 4. 20 @PIL-C6 was sequentially added to a 25 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, containing 17.2 mmol (1.6 g) of epichlorohydrin and Zn-TPMO. 20 @PIL-C60.18 g, accounting for 10 wt.% of the reactants; 10% CO2 gas was slowly introduced into the reactor to remove residual air; then, 10% CO2 gas was introduced to maintain a constant pressure of 1.5 MPa, and the reactor was heated to 120 °C in an oil bath for 3 hours; after the reaction was completed, the reactor was cooled to room temperature in an ice-water bath, and the product was quantitatively analyzed by gas chromatography-mass spectrometry. The yield of chloropropylene carbonate was 89%, and the selectivity was ≥99%.

[0066] Example 11

[0067] The experimental procedure was as described in Example 5, using Zn-TPMO prepared in Example 4. 20 Using @PIL-C6 as a catalyst, different epoxides were reacted with carbon dioxide at 110 °C, 1.0 MPa, 17.2 mmol of epoxide and 6 wt% catalyst. The results are shown in Table 1.

[0068] Table 1 Zn-TPMO 20 Results of the cycloaddition reaction of carbon dioxide with different epoxides catalyzed by PIL-C6

[0069]

[0070] Examples 12-16

[0071] The specific experimental conditions and procedures are the same as in Example 6, except that the catalyst Zn-TPMO is used instead. 20 @PIL-C6 was replaced with Zn-TPMO recovered in Example 6. 20 @PIL-C6, five cycles of the experiment were performed under the same conditions, and the results are shown in Table 2.

[0072] Table 2 Results of catalyst reuse experiments in Examples 13-17

[0073]

[0074] Example 17

[0075] To further illustrate the advantages of the present invention, Table 3 below compares one of the porous heterostructure materials proposed in the present invention with other porous heterostructure catalysts reported in the literature. Specifically, the conditions in the literature are as described in this embodiment, with only the temperature, pressure, and time being extracted. The catalyst provided by the present invention shows significant advantages in terms of catalytic reaction conditions and activity.

[0076] Table 3 Comparison of the activities of porous heterostructure catalysts with those reported in the literature.

[0077]

[0078] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A functional organosilicon-coupled polyionic liquid heterostructure material, characterized in that, It is prepared by a method including the following steps: S1: Preparation of metalloporphyrin-based silicon source precursor In anhydrous acetone, Zn-5,10,15,20-tetra(4-aminophenyl)porphyrin was reacted with propyltriethoxysilane isocyanate in a certain proportion. After the reaction was completed, the solvent was removed to obtain a metalloporphyrin-based silicon source precursor. S2: Preparation of metalloporphyrin-based periodic mesoporous organosilicon The metal porphyrin-based silicon source precursor obtained in step S1 is blended with tetraethyl silicate in the presence of a surfactant and then subjected to hydrolysis and copolymerization to generate metal porphyrin-based periodic mesoporous organosilicon. S3: Synthesis of divinylimidazolium salt 1-Vinylimidazole was reacted with 1,6-dibromohexane, 1,4-dibromobutane or 1,2-dibromoethane in tetrahydrofuran solvent under static hydrothermal conditions to obtain divinylimidazole salts with different carbon numbers. S4: Synthesis of metalloporphyrin-functionalized organosilicon-coupled polyionic liquid porous heterostructure The bisvinylimidazolium salt obtained in step S3 was subjected to in-situ polymerization on the metal porphyrin-based periodic mesoporous organosilicon framework obtained in step S2 under the action of the initiator 2,2'-azobisisobutyronitrile, to obtain a functional organosilicon coupled polyionic liquid heterostructure material.

2. The functional organosilicon-coupled polyionic liquid heterostructure material according to claim 1, characterized in that, In step S1, the molar ratio of Zn-5,10,15,20-tetra(4-aminophenyl)porphyrin to propyltriethoxysilane isocyanate is 1:4~4.5; in step S2, the molar ratio of the metalloporphyrin-based silicon source precursor to tetraethyl silicate silicon is 1:10~20; in step S3, the molar ratio of 1-vinylimidazolium to 1,6-dibromohexane, 1,4-dibromobutane, or 1,2-dibromoethane is 2~2.5:1; in step S4, the mass ratio of bisvinylimidazolium salt to metalloporphyrin-based periodic mesoporous organosilicon is 1:1~1.

2.

3. The functional organosilicon-coupled polyionic liquid heterostructure material according to claim 1, characterized in that, The reaction temperature in step S1 is 50-80℃, and the reaction time is 40-50h. The reaction conditions for step S2 are as follows: first, stir at 40~50℃ for 20~24 h to form a uniform emulsion system; then transfer it to a hydrothermal reactor and statically heat at 100~150℃ for 90~100 h. The reaction conditions for step S3 are as follows: first stir at room temperature for 1-2 h, then transfer the mixture to a hydrothermal reactor and statically heat at 80-100℃ for 20-24 h; The reaction conditions for step S4 are as follows: first, half of the 2,2-azobisisobutyronitrile is added to the mixture, heated to 40~60℃ and stirred for 20~24 h, then the remaining 2,2-azobisisobutyronitrile is dissolved in methanol and added to the mixture, and the mixture continues to react for 40~48 h.

4. The application of a functional organosilicon-coupled polyionic liquid heterostructure material as described in any one of claims 1-3 in the catalytic conversion of low-concentration carbon dioxide, characterized in that, The application is to catalyze the reaction of low-concentration carbon dioxide with epoxides to synthesize cyclic carbonates.

5. A method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using a functional organosilicon-coupled polyionic liquid heterostructure material as described in any one of claims 1-3, characterized in that, Using functional organosilicon coupled with polyionic liquid heterostructure material as a catalyst, cyclic carbonates are synthesized from epoxides and low-concentration carbon dioxide through cycloaddition reaction.

6. The method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using a functional organosilicon-coupled polyionic liquid heterostructure material according to claim 5, characterized in that, The structural formula of the epoxide is as follows: 。 7. The method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using a functional organosilicon-coupled polyionic liquid heterostructure material according to claim 5, characterized in that, The amount of the functional organosilicon coupled polyionic liquid heterostructure catalyst is 2wt% to 10wt% of the mass of the reaction system.

8. The method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using a functional organosilicon-coupled polyionic liquid heterostructure material according to claim 5, characterized in that, The cycloaddition reaction is carried out at a temperature of 80-120℃, a pressure of 0.5-1.5 MPa, and a time of 3-7 hours.

9. The method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using a functional organosilicon-coupled polyionic liquid heterostructure material according to claim 5, characterized in that, The functional organosilicon-coupled polyionic liquid heterostructure material is Zn-TPMO20@PIL-C6.

10. The method for synthesizing cyclic carbonates by catalyzing the reaction of low-concentration carbon dioxide with epoxides using a functional organosilicon-coupled polyionic liquid heterostructure material according to claim 5, characterized in that... The low concentration of carbon dioxide is 10-15%.

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