Efficient and stable Lewis acid-containing heterogeneous catalyst as well as preparation method and application thereof

Abstract

The invention discloses an efficient and stable heterogeneous catalyst containing Lewis acid as well as a preparation method and application of the efficient and stable heterogeneous catalyst, and belongs to the technical field of cycloaddition reaction catalysts. The heterogeneous catalyst has groups with strong nucleophilicity and strong electrophilicity. The Lewis acid-containing raw material is selected from one of zinc acetate, cobalt acetate, copper acetate, ferrous acetate, magnesium acetate, nickel acetate, calcium acetate, manganese acetate, lead acetate and tin acetate. The prepared heterogeneous catalyst containing Lewis acid is applied to catalysis of cycloaddition reaction of epoxide and CO2, and the cycloaddition reaction of ethylene oxide (EO) / propylene oxide (PO) and CO2 is preferentially adopted. The problems that a homogeneous catalyst is difficult to separate and a heterogeneous catalyst is insufficient in activity are preferably solved.

Description

Technical Field

[0001] The present application relates to an efficient and stable Lewis acid-containing heterogeneous catalyst and a preparation method and application thereof, belonging to the technical field of cycloaddition reaction catalysts. Background Art

[0002] Carbon dioxide (CO2) is one of the greenhouse gases that contributes to global warming and extreme climate change. However, it is considered a non-toxic and economical C1 resource. Therefore, the efficient conversion of CO2 into high-value chemicals (such as low-carbon alcohols, low-carbon hydrocarbons, cyclocarbonates, amides, carboxylic acids, or nitrogen heterocyclic compounds) has received extensive attention in terms of resource conversion and the environment. The cycloaddition reaction of CO2 with epoxides is one of the most successful reactions because of its advantages of high atom utilization and low cost. In addition, cyclocarbonates are an important industrial raw material with a wide range of applications in lithium-ion battery electrolytes, polar aprotic solvents, additives, pharmaceutical intermediates, and polycarbonates.

[0003] Since CO2 has high thermodynamic stability and kinetic inertness, most chemical conversion reactions based on it require the use of efficient catalysts. So far, metal halides, quaternary ammonium salts, quaternary phosphonium salts, ionic liquids, poly (ionic liquids), organic bases, metal complexes, metal-organic frameworks, conjugated organic frameworks, supported catalysts, etc. have been used for the cycloaddition reaction of epoxides and CO2. However, many catalysts have disadvantages such as low stability or catalytic activity and the need for co-catalysts. Among them, ionic liquids as catalysts have solved these problems to a certain extent. Ionic liquids have adjustable structures and good thermal stability. They are often used in the cycloaddition reaction of PO and CO2, and have achieved valuable results. Since then, studies have found that metal ions can participate in the reaction of CO2 and PO as Lewis acid active sites. For this reason, metal salts (ZnBr2) have been widely used as co-catalysts in the cycloaddition reaction of PO and CO2. Compared with traditional ionic liquids, the catalytic performance has been greatly improved. However, homogeneous catalysts have disadvantages such as high energy consumption and polymerization of epoxides in the separation method of high-temperature distillation. To address these issues, a large number of metal-containing heterogeneous catalysts have been developed to catalyze the cycloaddition reaction of PO with CO2. However, although several heterogeneous catalysts have shown good performance in catalyst separation and product purification, they are not ideal in practical applications due to their low catalytic activity. As mentioned above, ionic liquids containing metal salts have better activity than traditional ionic liquids. Therefore, heterogeneous ionic liquids containing metal salts are considered to be an effective strategy for developing efficient heterogeneous ionic liquid catalysts. Summary of the invention

[0004] In order to solve the problems of difficulty in separation of homogeneous metal salt-containing ionic liquid catalysts in the prior art for synthesizing PC by the cycloaddition reaction of EO / PO and CO2, low activity of heterogeneous catalysts, easy loss of active components and complex catalyst preparation process, the present application provides a highly efficient and stable Lewis acid-containing heterogeneous catalyst and a preparation method and application thereof, which utilizes the strong nucleophilicity and strong electrophilic groups in the catalyst structure and solves the aforementioned technical problems, and exhibits super stability and excellent activity in the cycloaddition reaction of PO / EO and CO2.

[0005] This application adopts the following technical solutions:

[0006] A highly efficient and stable Lewis acid-containing heterogeneous catalyst, wherein the highly efficient and stable Lewis acid-containing heterogeneous catalyst has a structure shown in Formula I:

[0007]

[0008] Among them, R 1 , R 2 independently selected from C1-C6 alkylene groups, n 1 、n 2 Independently, 1000-3000;

[0009] M is selected from at least one of Zn, Co, Cu, Fe, Mg, Ni, Ca, Mn, Pb, and Sn.

[0010] The active centers are electrophilic cations and nucleophilic halide ions.

[0011] According to another aspect of the present application, there is provided a method for preparing the above-mentioned efficient and stable Lewis acid-containing heterogeneous catalyst, comprising the following steps:

[0012] S1, placing chloromethyl polystyrene resin in solvent I to swell, then adding nitrogen-containing heterocyclic ring, reacting I, to obtain precursor I;

[0013] S2, adding an organic raw material to a mixture containing precursor I and solvent II, heating reaction II to obtain precursor II;

[0014] S3, adding the Lewis acid-containing raw material to the mixture containing the precursor II and the solvent III, heating the reaction III, and obtaining the highly efficient and stable Lewis acid-containing heterogeneous catalyst.

[0015] Optionally, in step S1, the chloromethyl polystyrene resin has a structure represented by Formula II:

[0016] Wherein, R is selected from C1-C6 alkylene, n=1000-3000;

[0017] Optionally, in step S1, the crosslinking degree of the chloromethyl polystyrene resin is 4-10%, and the chlorine content is 15-25%.

[0018] Optionally, in step S1, the solvent I is selected from at least one of acetonitrile, methanol, ethanol, diethyl ether, acetone ethyl acetate, and petroleum ether.

[0019] Optionally, in step S1, the molar ratio of the chlorine element in the chloromethyl polystyrene resin to the nitrogen-containing heterocycle is 1:1-10.

[0020] Optionally, in step S1, the nitrogen-containing heterocycle is selected from the structure shown in formula III-1:

[0021]

[0022] Optionally, in step S1, the conditions of reaction I include: reaction temperature of 60 to 80° C., reaction time of 1 to 24 h;

[0023] Optionally, in step S1, the swelling conditions include: stirring at 60-80°C for 0.5-2h.

[0024] Optionally, in step S2, the organic raw material is selected from bromoacetic acid.

[0025] Optionally, in step S2, the solvent II is selected from at least one of methanol, ethanol, ethylene glycol, acetonitrile, ethyl acetate, and petroleum ether.

[0026] Optionally, in step S2, the molar ratio of the organic raw material to the solvent II is 1:1-15.

[0027] Optionally, in step S2, the molar ratio of the organic raw material to the precursor I is 1:0.8-1.

[0028] Optionally, in step S2, the conditions for heating reaction II include: reaction temperature of 70 to 110° C., and reaction time of 1 to 24 h.

[0029] Optionally, in step S3, the Lewis acid raw material is selected from at least one of zinc acetate, cobalt acetate, copper acetate, ferrous acetate, magnesium acetate, nickel acetate, calcium acetate, manganese acetate, and lead acetate;

[0030] Optionally, in step S3, the solvent III is selected from at least one of methanol, ethanol, and ethylene glycol;

[0031] Optionally, in step S3, the molar ratio of the Lewis acid-containing raw material to the solvent III is 1:1 to 15;

[0032] Optionally, in step S3, the molar ratio of the Lewis acid-containing raw material to the precursor II is 1:0.8-1.

[0033] Optionally, in step S3, the conditions of the heating reaction III include: a temperature of 50 to 90° C. and a reaction time of 1 to 24 hours.

[0034] Optionally, in step S3, the temperature in the heating reaction III is selected from any value of 50°C, 60°C, 70°C, 80°C, 90°C, or any range therebetween.

[0035] Optionally, in step S3, the reaction time in the conditions of the heating reaction III is selected from any value of 1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any range between two of them.

[0036] Optionally, the reaction I, reaction II, and reaction III are independently carried out under stirring conditions.

[0037] Optionally, the reaction I, reaction II, and reaction III may independently further include washing and drying steps.

[0038] Optionally, the washing conditions include: adding a washing solvent in an amount of 2 to 5 times the weight of the product to the product after the reaction, stirring, washing, and filtering.

[0039] The washing solvent is selected from at least one of methanol, ethanol, acetonitrile, ethyl acetate, acetone, benzene, toluene and xylene.

[0040] Optionally, the drying conditions include: vacuum drying at 60-80° C. for 6-24 hours.

[0041] According to another aspect of the present application, there is also provided an application of the above-mentioned efficient and stable Lewis acid-containing heterogeneous catalyst or the efficient and stable Lewis acid-containing heterogeneous catalyst prepared according to the above-mentioned preparation method in catalyzing the cycloaddition reaction of epoxide and CO2 to prepare propylene carbonate.

[0042] Optionally, the epoxide is selected from ethylene oxide and / or propylene oxide;

[0043] Optionally, the reaction temperature window of the homogeneous catalyst is 80-160°C.

[0044] Optionally, the reaction temperature window of the homogeneous catalyst is selected from any value of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C or any range therebetween.

[0045] In the present application, "PS-[EIMBr-COO]2Co" refers to 1-methyl-3-cobalt ethylimidazolium bromide.

[0046] In the present application, "PS-[EIMBr-COO]2Zn" refers to 1-methyl-3-zincethylimidazolium bromide.

[0047] In the present application, "PS-[EIMBr-COO]2Cu" refers to 1-methyl-3-copper ethylimidazolium bromide.

[0048] In the present application, "PS-[EIMBr-COO]2Fe" refers to 1-methyl-3-ferroethylimidazolium bromide.

[0049] In the present application, "PS-[EIMBr-COO]2Mg" refers to 1-methyl-3-magnesiumethylimidazolium bromide.

[0050] In the present application, "PS-[EIMBr-COO]2Ni" refers to 1-methyl-3-nickelethylimidazolium bromide.

[0051] In the present application, "PS-[EIMBr-COO]2Mn" refers to 1-methyl-3-manganeseethylimidazolium bromide.

[0052] As used herein, "EO" refers to ethylene oxide.

[0053] In this application, "PO" means propylene oxide.

[0054] In this application, "CO2" refers to carbon dioxide.

[0055] As used herein, "EC" refers to ethylene carbonate.

[0056] In this application, "PC" means propylene carbonate.

[0057] The beneficial effects of this application include:

[0058] The highly efficient and stable Lewis acid-containing heterogeneous catalyst provided by the present application, and its preparation method and application, have strong nucleophilicity and strong electrophilicity groups, show super stability and excellent catalytic activity in cycloaddition reactions, and the prepared Lewis acid-containing heterogeneous catalyst has good substrate adaptability in different epoxide and CO2 cycloaddition reactions. The problems of harsh reaction conditions, low catalyst activity, and poor stability of heterogeneous catalysts in the prior art are solved. The highly efficient and stable Lewis acid-containing heterogeneous catalyst preparation method provided by the present application synthesizes the precursor by a simple method, and introduces the Lewis acid active site (metal) by a common solvent method. The preparation process is simple and the operation is friendly, which overcomes the problem of low activity of heterogeneous catalysts in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of the synthesis process of the precursor and Lewis acid-containing heterogeneous catalyst of the present application.

[0060] Figure 2 Schematic diagram of the structure of the Lewis acid heterogeneous catalyst series in this application.

[0061] Figure 3 This is the infrared spectrum of the catalyst sample prepared in this application.

[0062] Figure 4 This is the thermogravimetric diagram of the catalyst sample prepared in this application.

[0063] Figure 5 This is the effect of reaction temperature on the catalytic performance of the heterogeneous catalyst PS-[EIMBr-COO]2Co (EO / CO2) in this application.

[0064] Figure 6 This application studies the effect of reaction temperature on the catalytic performance of the heterogeneous catalyst PS-[EIMBr-COO]2Co (PO / CO2).

[0065] Figure 7 This is an evaluation of the effect of reaction time on the catalytic performance of the heterogeneous catalyst PS-[EIMBr-COO]2Co in this application.

[0066] Figure 8 This is the effect of reaction pressure on the catalytic performance of the heterogeneous catalyst PS-[EIMBr-COO]2Co in this application.

[0067] Fig. 9 The catalytic stability of the heterogeneous catalyst PS-[EIMBr-COO]2Co was evaluated for this application.

[0068] Fig.10 This is an infrared image of a sample of the catalyst prepared in this application after use.

[0069] Fig.11 In this application, the heterogeneous catalyst PS-[EIMBr-COO]2Co was used to evaluate the reaction of different substrates with CO2. DETAILED DESCRIPTION

[0070] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0071] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0072] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0073] In the examples of the present application, acid amount calculation, nuclear magnetic H spectrum analysis, nuclear magnetic C spectrum analysis (AscendⅢ500MHz liquid-solid dual-purpose nuclear magnetic resonance instrument, Bruker, Switzerland) and infrared spectrum analysis (IRTracer-100 Fourier transform infrared spectrometer, Shimadzu, Japan), thermogravimetric and differential thermal analysis (TG-DTA8122), characterization analysis are all routine operations, and those skilled in the art can operate according to the instrument instructions.

[0074] In the examples of the present application, the PO conversion, PC selectivity, PC yield and TOF value are calculated as follows:

[0075] X PO / % = (n PC) × 100 / (n PC + n PO ) (1)

[0076] S PC / % = nPC × 100 / (n PC + n byproducts) (2)

[0077] Y PC / % = X PO × S PC (3)

[0078] TOF=(n PO × PC yield) / (n Cat. ×t) (4)

[0079] In the formula, X PO is the conversion rate of PO, S PC is the selectivity of PC, Y PC is the yield of PC, n PO is the molar mass of PO, n PC is the molar mass of PC, n Cat is the molar mass of the active sites in the catalyst, and t is the reaction time.

[0080] The EO conversion, EC selectivity, EC yield and TOF value in the test examples of this application are calculated as follows:

[0081] X EO / % = (nEC) × 100 / (n EC + n EO ) (1)

[0082] S EC / % = nEC × 100 / (n EC + n byproducts) (2)

[0083] YEC / % = X EO × S EC (3)

[0084] TOF=(n EO ×EC yield) / (n Cat. ×t) (4)

[0085] In the formula, X EO is the conversion rate of EO, S EC is the selectivity of EC, Y EC is the yield of EC, n EO is the molar mass of EO, n EC is the molar mass of EC, n Cat is the molar mass of the active sites in the catalyst, and t is the reaction time.

[0086] Example 1 Heterogeneous catalyst containing Lewis acid

[0087] Synthesis mechanism Figure 1 As shown, the steps include:

[0088] S1. Add 10 g of PS-Cl into acetonitrile and stir for 1 h. Then dissolve 4 g of imidazole in the above solution and stir for 24 h. Wash the product with acetonitrile and dry it at -0.1 MPa and 70 °C for 12 h. The obtained precursor I is named PS-IM.

[0089] S2. Add the precursor synthesized in step S1 and 30 ml of acetonitrile into a 250 ml three-necked round-bottom flask, dissolve bromoacetic acid (0.05 mol) in the above solution and stir. After reflux at 70° C. for 24 h, wash the product with ethyl acetate three times and vacuum dry at 70° C. for 24 h to obtain a heterogeneous catalyst and a precursor II named PS-[ECOOHIM]Br.

[0090] S3, PS-[ECOOHIM]Br synthesized in step S2 and 60ml methanol (MeOH) were added to a 250ml three-necked round-bottom flask, and cobalt acetate (0.05mol) was dissolved in the above solution and stirred. Refluxed at 70°C for 24h, after the complexation reaction was completed, washed with MeOH three times, and then dried in a vacuum oven at 70°C for 24h, and finally an efficient and stable Lewis acid-containing heterogeneous catalyst was obtained, named PS-[EIMBr-COO]2Co.

[0091] Examples 2-7 Different Lewis acid (metal ion) containing heterogeneous catalysts

[0092] The preparation method is the same as that of Example 1, except that the cation structure is different. In Examples 2 to 7, cobalt acetate is replaced by zinc acetate, copper acetate, iron acetate, magnesium acetate, nickel acetate, and manganese acetate, respectively. A series of catalysts containing different metal ions are synthesized and named PS-[EIMBr-COO]2Y, where Y represents Zn, Cu, Fe, Mg, Ni, and Mn. The structure of the prepared PS-[EIMBr-COO]2Y is as follows: Figure 2 shown.

[0093] Test Example 1 Fourier Transform Infrared Spectroscopy (FT-IR) Characterization

[0094] Taking the Lewis acid heterogeneous catalyst PS-[EIMBr-COO]2Co sample prepared in Example 1 as an example, Figure 3 The characteristic peaks of the imidazole ring group were clearly observed. 3131~2925cm -1 The absorption peak is caused by the CH stretching vibration of the alkyl group substituted by the imidazole ring. -1 and 1149cm -1 The absorption peak at 1168cm is caused by the stretching vibration of the C=N and C=C bonds in the imidazole ring. -1 There is an in-plane bending vibration peak at 825-750cm -1 The absorption peaks at belong to the in-plane and out-of-plane bending vibrations of the CH bonds of the imidazole ring. 2+ During the functionalization process, the imidazole groups of the samples can be stably present. -1 The absorption peak at is attributed to the C=O stretching vibration of the -COOH group in PS-[EIMBr-COO]2Co. The above experimental results prove the successful synthesis of PS-[EIMBr-COO]2Co.

[0095] Test Example 2 Thermogravimetric-differential thermal analysis (TG-DTA) characterization

[0096] Taking the Lewis acid-containing heterogeneous catalyst PS-[EIMBr-COO]2Co sample prepared in Example 1 as a typical example, Figure 4The TG and DTA data of PS-[EIMBr-COO]2Co are given. The initial decomposition temperature of PS-[EIMBr-COO]2Co is above 223℃. It can be inferred that the synthesized catalyst has good thermal stability. The thermogravimetric curve of PS-[EIMBr-COO]2Co can be divided into three weight loss stages. The first weight loss stage (25-223℃) is 3.77%, which is mainly due to the departure of a small amount of bound water and solvent molecules. In the second stage (223-438℃), the cleavage of the CH bonds of the methyl and methylene groups leads to partial decomposition of the imidazolium cation, with a mass loss of 23.84%. The third stage (438-574℃) is the complete decomposition of the polystyrene resin, with a weight loss of 32.65%. It is worth noting that the initial decomposition temperature of PS-[EIMBr-COO]2Co (223℃) is much higher than the cycloaddition reaction temperature of PO and CO2 (110℃), which indicates that the synthesized PS-[EIMBr-COO]2Co maintains structural integrity throughout the reaction process.

[0097] Test Example 3 Effect of reaction temperature on the catalytic performance of heterogeneous catalyst PS-[EIMBr-COO]2Co (EO / CO2)

[0098] As attached Figure 5 As shown, the PS-[EIMBr-COO]2Co prepared in Example 1 is used as a catalyst to show the effect of different reaction temperatures on the synthesis of EC by the cycloaddition reaction of EO and CO2. The reaction conditions are 0.14 mol EO, 2.6 MPa CO2, 3.81×10 - 4 mol PS-[EIMBr-COO]2Co. The cycloaddition reaction of EO and CO2 catalyzed by PS-[EIMBr-COO]2Co was carried out at 90, 100, 110 and 120 °C, respectively. As the reaction temperature increased from 70 to 120 °C, the EC yield increased gradually and showed the following order: 90 °C (82.46%) > 100 °C (90.82%) > 110 °C (99.02%) > 120 °C (99.57%), while the related TOF values ​​showed the following order: 90 °C (92.33h -1 )<100℃(113.54h -1 )<110℃(121.75h -1 )<120℃(122.88h -1 ). Obviously, with the increase of temperature, the catalytic activity gradually increases, which is because the increase of temperature promotes the movement frequency of CO2 molecules and promotes the rapid contact between CO2 and EO in the liquid phase. The experimental results show that PS-[EIMBr-COO]2Co has excellent catalytic activity for catalyzing the cycloaddition reaction of EO and CO2.

[0099] Test Example 4 Effect of reaction temperature on the catalytic performance of heterogeneous catalyst PS-[EIMBr-COO]2Co (PO / CO2)

[0100] As attached Figure 6 As shown, the PS-[EIMBr-COO]2Co prepared in Example 1 was used as the catalyst, and different reaction temperatures affected the reaction of PO and CO2 to synthesize PC. The reaction conditions were 0.14 mol PO, 2.6 MPa CO2, 3.81×10 -4 molPS-[EIMBr-COO]2Co. The cycloaddition reaction of PO and CO2 catalyzed by PS-[EIMBr-COO]2Co was carried out at 70, 80, 90, 100, 110 and 120 °C, respectively. As the reaction temperature increased from 70 to 120 °C, the PC yield gradually increased and showed the following order: 90 °C (72.36%) > 100 °C (84.82%) > 110 °C (98.92%) > 120 °C (99.03%), while the related TOF values ​​showed the following order: 90 °C (88.33h -1 )<100℃(103.54h -1 )<110℃(120.75h -1 )<120℃(120.88h -1 ). Obviously, with the increase of temperature, the catalytic activity gradually increases. This is because the increase of temperature promotes the movement frequency of CO2 molecules and promotes the rapid contact between CO2 and PO in the liquid phase.

[0101] Test Example 5 Evaluation of the effect of reaction time on the catalytic performance of the heterogeneous catalyst PS-[EIMBr-COO]2Co

[0102] As attached Figure 7 As shown, the PS-[EIMBr-COO]2Co prepared in Example 1 is used as a catalyst to show the effect of different reaction times on the synthesis of PC by the cycloaddition reaction of PO and CO2. The reaction conditions are 0.14 mol PO, 110 °C, 3.81×10 -4 molPS-[EIMBr-COO]2Co. The reaction time was extended from 1 to 2 h, the PC yield increased from 79.32% to 86.53%, and the TOF values ​​were 290.47 and 158.44 h, respectively. -1 When the reaction time was extended to 3 h, the PC yield increased to 98.92% and the TOF value was 120.75 h -1 It is worth noting that when the reaction time was extended to 4 h, the PC yield and TOF value were 99.01% and 90.64 h, respectively. -1, which is basically the same as the result at 3h. The experimental results show that the PC yield of the reaction system increases with the increase of reaction time. However, the reaction rate in the later stage is very slow, indicating that the decrease in the concentration of effective PO molecules is the key factor for the low reaction rate. At the same time, it is believed that further extending the reaction time will lead to the polymerization of PC and the generation of side reactions such as PO isomerization and hydration. The results show that the most suitable reaction time for the cycloaddition reaction of PO and CO2 is 3h.

[0103] Test Example 6 Effect of reaction pressure on the catalytic performance of heterogeneous catalyst PS-[EIMBr-COO]2Co

[0104] As attached Figure 8 As shown, the PS-[EIMBr-COO]2Co prepared in Example 1 is used as a catalyst to show the effect of different CO2 pressures on the synthesis of PC by the cycloaddition reaction of PO and CO2. The reaction conditions are 0.14 mol PO, 110 °C, 3.81×10 -4 mol PS-[EIMBr-COO]2Co. When the initial CO2 pressure was 2.2MPa (CO2 / PO molar ratio was 1.2 / 1), the PC yield reached 87.35% and the TOF value was 106.62h -1 Under the condition of initial CO2 pressure of 2.4MPa (CO2 / PO molar ratio of 1.4 / 1), PC yield was 91.38% and TOF value was 111.55h -1 When the initial CO2 pressure was 2.6MPa (CO / PO molar ratio was 1.6 / 1), the PC yield decreased to 98.92% and the TOF value increased to 120.75h -1 However, when the initial CO2 pressure continued to increase to 2.8MPa (CO2 / PO molar ratio of 2.0 / 1) and 3.0MPa (CO2 / PO molar ratio of 2.0 / 1), the PC yield decreased to 92.26% and 92.98%, respectively, and the TOF value decreased to 112.62 and 113.49h, respectively. -1 With the increase of CO2 pressure (2.2-2.6 MPa), the continuous dissolution of CO2 in the PO phase also increased, promoting the cycloaddition reaction. In contrast, excess CO2 (2.6-3.0 MPa) not only hindered the interaction between PS-[EIMBr-COO]2Co and PO, but also diluted the PO concentration in the bottom phase, resulting in a decrease in PC yield.

[0105] Test Example 7 Evaluation of the catalytic stability of the heterogeneous catalyst PS-[EIMBr-COO]2Co

[0106] As attached Fig. 9As shown, taking PS-[EIMBr-COO]2Co prepared in Example 1 as a catalyst as an example, under the optimal reaction conditions (110°C, 2.6MPa, 3.81×10 -4 The cycloaddition reaction of PO with CO2 was carried out 7 times at 37 °C (100 mol, 3 h) to evaluate its recyclability and reusability. PS-[EIMBr-COO]2Co was easily separated from the reaction mixture by filtration, and the catalyst was washed with methanol and dried at 70 °C for 24 h. The PC yield in different cycles also varied slightly (from 98.92% to 98.87%), while maintaining consistent PC selectivity. The structural integrity of the recovered catalyst was confirmed by FT-IR characterization analysis. Comparing the FT-IR characteristic peaks of fresh and recycled PS-[EIMBr-COO]2Co catalysts, such as Fig.10 As shown, their peak positions were found to be almost the same, indicating that there was no obvious change in the catalyst structure.

[0107] Test Example 8 Evaluation of the reaction of different substrates with CO2 catalyzed by the heterogeneous catalyst PS-[EIMBr-COO]2Co

[0108] Taking PS-[EIMBr-COO]2Co prepared in Example 1 as a typical catalyst, under the optimal reaction conditions (110°C, 2.6MPa, 3.81×10 -4 mol, 3h), epoxides with different substituents and CO2 were used to carry out cycloaddition to synthesize the corresponding cyclic carbonates. Fig.11As shown in Figure 2, after 3 h of reaction, the experimental results showed that PS-[EIMBr-COO]2Co could effectively catalyze various epoxides to the corresponding cyclic carbonates with high selectivity (>99%). It is noteworthy that PS-[EIMBr-COO]2Co was more effective for EO (a) and PO (b) than 1,2-butylene oxide (c) with larger alkyl side chains, with conversions of 99.52%, 98.92%, and 82.04%, respectively. This may be due to the restricted diffusion of longer alkyl chains (i.e., substrates with larger R groups) into the active sites within the catalyst, which reduces the conversion. Surprisingly, the conversions of epichlorohydrin (d) and glycidol (e) were significantly improved, reaching 96.91% and 95.64%, respectively. The electron-withdrawing properties of the halogen atoms in epichlorohydrin play a key stabilizing role in the intermediates formed during the ring-opening of epoxides, thereby promoting the cycloaddition reaction. The satisfactory conversion of glycerol may be due to the formation of intermolecular hydrogen bonds between glycerol molecules. In addition, in the cycloaddition reaction, ethylene glycol can act as both a substrate and a catalyst (hydrogen bond donor). Styrene oxide, phenyl glycidyl ether and allyl glycidyl ether (f, j and h) are widely considered to be difficult substrates and are rarely successfully converted. However, PS-[EIMBr-COO]2Co catalyzes the cycloaddition reaction of styrene, phenyl glycidyl ester and allyl glycidyl ester (f, j and h) with CO2 to successfully produce the corresponding cyclic carbonates. The corresponding substrate conversions were 80.85%, 84.22% and 84.91%, respectively. The relatively unsatisfactory catalytic activity can be explained by the relatively strong steric site resistance (strong conjugation effect), which hinders the diffusion of molecules and the contact of active sites with epoxides. In summary, the extension of various epoxides by PS-[EIMBr-COO]2Co catalysts reflects its excellent efficiency.

[0109] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An efficient and stable Lewis acid-containing heterogeneous catalyst, characterized in that: The highly efficient and stable Lewis acid-containing heterogeneous catalyst has a structure shown in Formula I: Among them, R 1 , R 2 independently selected from C1-C6 alkylene groups, n 1 、n 2 Independently, 1000-3000; M is selected from at least one of Zn, Co, Cu, Fe, Mg, Ni, Ca, Mn, Pb, and Sn.

2. The method for preparing the highly efficient and stable Lewis acid-containing heterogeneous catalyst according to claim 1, characterized in that: The steps include: S1, placing chloromethyl polystyrene resin in solvent I to swell, then adding nitrogen-containing heterocyclic ring, reacting I, to obtain precursor I; S2, adding an organic raw material to a mixture containing precursor I and solvent II, heating reaction II to obtain precursor II; S3, adding the Lewis acid-containing raw material to the mixture containing the precursor II and the solvent III, heating the reaction III, and obtaining the highly efficient and stable Lewis acid-containing heterogeneous catalyst.

3. The preparation method according to claim 2, characterized in that: In step S1, the chloromethyl polystyrene resin has a structure represented by formula II: Wherein, R is selected from C1-C6 alkylene, n=1000-3000; Preferably, in step S1, the crosslinking degree of the chloromethyl polystyrene resin is 4-10%, and the chlorine content is 15-25%; Preferably, in step S1, the solvent I is selected from at least one of acetonitrile, methanol, ethanol, diethyl ether, acetone ethyl acetate, and petroleum ether; Preferably, in step S1, the molar ratio of the chlorine element in the chloromethyl polystyrene resin to the nitrogen-containing heterocyclic ring is 1:1 to 10; Preferably, in step S1, the nitrogen-containing heterocycle is selected from the structure shown in formula III-1:

4. The preparation method according to claim 2, characterized in that: In step S1, the conditions of reaction I include: reaction temperature of 60 to 80° C., reaction time of 1 to 24 h; Preferably, in step S1, the swelling conditions include: stirring at 60-80°C for 0.5-2h.

5. The preparation method according to claim 2, characterized in that: The organic raw material is selected from bromoacetic acid; Preferably, in step S2, the solvent II is selected from at least one of methanol, ethanol, ethylene glycol, acetonitrile, ethyl acetate, and petroleum ether; Preferably, in step S2, the molar ratio of the organic raw material to the solvent II is 1:1 to 15; Preferably, in step S2, the molar ratio of the organic raw material to the precursor I is 1:0.8-1.

6. The preparation method according to claim 2, characterized in that: In step S2, the conditions for heating reaction II include: reaction temperature of 70 to 110° C., and reaction time of 1 to 24 h.

7. The preparation method according to claim 2, characterized in that: In step S3, the Lewis acid raw material is selected from at least one of zinc acetate, cobalt acetate, copper acetate, ferrous acetate, magnesium acetate, nickel acetate, calcium acetate, manganese acetate, lead acetate, and tin acetate; Preferably, in step S3, the solvent III is selected from at least one of methanol, ethanol and ethylene glycol; Preferably, in step S3, the molar ratio of the Lewis acid-containing raw material to the solvent III is 1:1 to 15; Preferably, in step S3, the molar ratio of the Lewis acid-containing raw material to the precursor II is 1:0.8-1.

8. The preparation method according to claim 2, characterized in that: In step S3, the conditions for the heating reaction III include: a temperature of 50 to 90° C. and a reaction time of 1 to 24 hours.

9. Use of the efficient and stable Lewis acid-containing heterogeneous catalyst according to claim 1 or the efficient and stable Lewis acid-containing heterogeneous catalyst prepared according to the preparation method according to any one of claims 2 to 8 in catalyzing the cycloaddition reaction of epoxide and CO2 to prepare propylene carbonate.

10. The use according to claim 9, characterized in that: The epoxide is selected from ethylene oxide, propylene oxide, 1,2-butylene oxide, epichlorohydrin, glycidol, styrene oxide, phenyl glycidyl ester and allyl glycidyl ester. Preferably, the reaction temperature window of the homogeneous catalyst is 80-160°C.

Images