Method for synthesizing carbonic ester under catalysis of metal coordination super-crosslinking polymeric ionic liquid
By using a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst, the problems of low efficiency and difficult separation in the synthesis of carbonates from CO2 and epoxides under mild conditions have been solved, achieving a highly efficient and easily separable catalytic effect suitable for a variety of substrates.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INSTITUTE OF PROCESS ENGINEERING CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-04
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies are difficult to efficiently catalyze the synthesis of carbonates from CO2 and epoxides under mild conditions. Traditional catalysts suffer from problems such as difficulty in controlling reaction conditions, high energy consumption, low catalyst utilization efficiency, and separation difficulties.
A metal-coordinated hypercrosslinked polymeric ionic liquid catalyst was developed by coordinating triphenylphosphine ionic liquid with a metal salt and combining it with a Friedel-Crafts alkylation reaction to prepare a catalyst with a high degree of crosslinking, enabling the efficient catalytic synthesis of carbonates without solvents or additives.
High catalytic yield and favorable reaction conditions were achieved under mild conditions. The catalyst is easy to separate, has a flexible distribution of active sites, requires a small amount of catalyst, and has high thermal stability, making it suitable for a variety of substrates.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of green and clean catalytic technology for CO2 capture and efficient conversion, specifically to a method for synthesizing a metal coordination type hypercrosslinked polymeric ionic liquid structure catalyst, which can catalyze the synthesis of carbonates from CO2 and epoxides through cycloaddition reaction under mild conditions. Background Technology
[0002] Carbon dioxide (CO2) is a major component of greenhouse gases and an abundant and readily available C1 resource. The efficient conversion and high-value utilization of CO2 as a raw material has been a hot topic in academia and industry. Under the induction of high-energy epoxide molecules, CO2 can be efficiently activated through cyclization reactions to synthesize carbonates, a representative atom-economic method that combines efficient conversion and high-value utilization. Due to its wide application in lithium-ion battery electrolytes, polycarbonate monomers, pharmaceutical production, and green additives, the resulting cyclic carbonates are very popular in domestic and international markets. However, traditional cyclization reactions often require high temperature and pressure (100–120℃, 2–5 MPa) to ensure reaction efficiency, leading to difficulty in process control and high energy consumption. Many researchers and institutions have developed homogeneous catalytic systems represented by metal salts, organic bases, and metal complexes, as well as heterogeneous catalytic systems represented by metal oxides, ion exchange resins, modified molecular sieves, and immobilized catalysts. Although these methods have reduced reaction temperature and pressure to some extent, activity and stability under the reaction conditions cannot be simultaneously achieved, and breakthrough progress in efficient catalysis under mild conditions (<90℃) has not yet been made.
[0003] Compared to traditional catalysts, ionic liquids exhibit higher catalytic activity through structural design and functionalization, effectively reducing reaction temperatures. However, the aggregation effect of homogeneous ionic liquids leads to low utilization efficiency in the reaction system, resulting in a large amount of ionic liquid consumed to achieve high catalytic activity, and separation is difficult. Supported ionic liquid catalytic systems can effectively simplify the separation process, but the presence of the support interface slows down the diffusion rate of large molecular reactants to the active sites of the catalyst, causing the catalytic efficiency of supported catalysts to be much lower than that of homogeneous ionic liquids. Summary of the Invention
[0004] The purpose of this invention is to propose a highly cross-linked supercrosslinked polymeric ionic liquid catalyst synthesized from ionic liquid monomers and crosslinking agents via Friedel-Crafts alkylation polymerization, followed by coordination with a metal salt to form a metal-coordinated supercrosslinked polymeric ionic liquid. This enables the efficient synthesis of carbonates from CO2 and epoxides under mild conditions without solvents or additives. Furthermore, the synthetic route is simple and easy to operate, and the catalyst activity can be easily adjusted by controlling the ratio of the raw monomers, resulting in advantages such as high catalytic yield, broad substrate versatility, mild reaction conditions, and simple recovery and separation.
[0005] The purpose of this invention is to provide a metal-coordinated hypercrosslinked polymeric ionic liquid with highly efficient catalytic ability for the synthesis of carbonates from CO2 and epoxides.
[0006] The metal-coordinated hypercrosslinked polymeric ionic liquid catalyst of the present invention has the structure of Formula 1:
[0007]
[0008] The second objective of this invention is to provide a metal coordination polymeric ionic liquid for the synthesis of carbonates from CO2 and epoxides. Triphenylphosphine ionic liquids possess characteristics such as high designability, ease of synthesis, and effective reduction of reaction activation energy. Furthermore, triphenylphosphine can be introduced into the polymeric ionic liquid through coordination with metal salts, easily solving the problem of catalyst separation and recovery. By adjusting the ratio of monomer to crosslinking agent, the distribution of active sites can be flexibly controlled, maximizing the catalytic effect of the ionic liquid and metal.
[0009] Preferably, the monomer and crosslinking agent are prepared by Friedel-Crafts alkylation polymerization in a certain proportion.
[0010] The preparation method of the metal coordination hypercrosslinked polymeric ionic liquid catalyst is characterized by comprising the following steps:
[0011] (1) Triphenylphosphine and p-dibenzyl bromide were mixed in solvent 1,2-dichloroethane under an inert gas atmosphere to generate triphenylbenzylphosphine bromide ionic liquid monomer, and then anhydrous ferric chloride was added to carry out Friedel-Crafts alkylation reaction to obtain the corresponding hypercrosslinked polymeric ionic liquid.
[0012] (2) The obtained hypercrosslinked polymeric ionic liquid needs to be dried to constant weight in a vacuum oven at 70°C to remove a small amount of solvent.
[0013] (3) The obtained hypercrosslinked polymeric ionic liquid swelled in the solvent tetrahydrofuran solution for 4 hours, and then metal salt was added and stirred for 24 hours for coordination. The obtained metal-coordinated hypercrosslinked polymeric ionic liquid needed to be dried to constant weight in a vacuum oven at 70°C.
[0014] Preferably, the metal salt includes ZnCl2, ZnBr2, ZnI2, MnBr2, CoBr2, NiBr2,
[0015] Any one of them.
[0016] Preferably, the catalyst dosage is 0.01 to 0.08 mol% of the reactant epoxide, for example, 0.01 mol%, 0.02 mol%, 0.03 mol%, 0.04 mol%, 0.05 mol%, 0.06 mol%, 0.08 mol%, preferably 0.01 to 0.06 mol%.
[0017] Preferably, the method for preparing carbonate is characterized in that the temperature of the cycloaddition reaction is 30-130°C; for example, 30°C, 50°C, 70°C, 90°C, 110°C, 120°C, 130°C, preferably 30°C-110°C.
[0018] Preferably, the reaction time of the cycloaddition reaction is 0.5 to 24 hours; for example, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 10 hours, 15 hours, 24 hours, preferably 0.5 hours to 4 hours.
[0019] Preferably, the method for preparing carbonates is characterized in that the epoxy compound includes any one or at least two combinations of ethylene oxide, propylene oxide, butane oxide, epichlorohydrin, styrene oxide, cyclohexane oxide, and cyclopentane oxide.
[0020] Preferably, the preparation method includes the following steps:
[0021] The epoxide compound and catalyst are placed in a sealed reactor and the reactor temperature is allowed to reach any target temperature between 30°C and 110°C. Carbon dioxide gas is introduced into the reactor and the pressure inside the reactor is maintained at 1 MPa. The reaction system undergoes a cycloaddition reaction for 0.5 to 4 hours to obtain carbonate.
[0022] Preferably, the yield of the carbonate is 45.5% to 97.6%.
[0023] Compared with previous patents, the advantages of this invention are:
[0024] (1) In this invention, a triphenylphosphine-based ionic liquid and other monomers are polymerized by Friedel-Crafts alkylation to form a heterogeneous catalyst. Then, metal sites are introduced through simple coordination to obtain a metal-coordinated hypercrosslinked polymeric ionic liquid with a crosslinked network structure. This is beneficial for the exposure and mass transfer of multiple active sites, thereby maximizing the catalytic effect. The ionic liquid carries bromide anions, which can synergistically catalyze with metals to promote the reaction of CO2 and epoxides and generate the corresponding carbonates with high efficiency.
[0025] (2) Compared with other polymeric ionic liquids, the catalyst in this invention has a decomposition temperature of 300℃, high thermal stability, very low catalyst dosage, high activity, reaction conditions close to room temperature, simple preparation steps, easy product separation, and good cycle performance. It can solve the problems of homogeneous catalysts and heterogeneous catalysts in many ways. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the system provided in specific embodiment 1 of the present invention. Detailed Implementation
[0027] To facilitate a better understanding of the present invention, specific embodiments are provided below for further explanation. However, the present invention is not limited to the technical scope of the embodiments; all embodiments described herein fall within the technical scope of the present invention without departing from the spirit and intent described above.
[0028] The preparation steps of hypercrosslinked polymeric ionic liquids are as follows:
[0029] Step 1: Synthesis of polymeric ionic liquids
[0030] For example, triphenylphosphine and p-dibenzyl bromide were added in a certain ratio to a 100 mL three-necked flask, and 30 mL of 1,2-dichloroethane was added as a solvent. The three-necked flask was kept under a nitrogen atmosphere throughout the reaction, and the reaction was carried out at an oil bath temperature of 45 °C for 4 h. Then, a certain amount of triphenylphosphine and anhydrous ferric chloride were added to carry out a Friedel-Crafts alkylation reaction. After the reaction was completed, the solvent in the system was removed by vacuum rotary evaporation, and a crude super-crosslinked polymeric ionic liquid product was obtained. The product was then washed repeatedly with methanol and deionized water, and the resulting brown solid was placed in a vacuum oven at 70 °C and dried to constant weight, thus obtaining the first step of the super-crosslinked polymeric ionic liquid.
[0031] Step 2: Synthesis of metal-coordinated hypercrosslinked polymeric ionic liquids
[0032] For example, the hypercrosslinked polymeric ionic liquid monomer prepared in the first step was added to 50 ml of tetrahydrofuran as a solvent and swollen for 4 h. Then, a metal was added in a certain proportion, nitrogen was introduced as a protective atmosphere, and the solution was stirred at 200 r / min for 24 h to allow the triphenylphosphine and metal in the polymeric ionic liquid to fully coordinate. After the reaction was completed, the mixture was separated by filtration to obtain a certain amount of metal-coordinated hypercrosslinked polymeric ionic liquid. Then, the unreacted metal and impurities in the solid were washed with tetrahydrofuran, ethanol, and deionized water. The solid was dried in a vacuum drying oven at 70 °C for 24 h to remove a small amount of solvent. The dried sample was ground into powder and sieved to obtain the metal-coordinated polymeric ionic liquid catalyst to be evaluated.
[0033] The metal-coordinated hypercrosslinked polymeric ionic liquids in the above steps can be modified by changing the monomers, and the coordinating metals can also be arbitrarily controlled, thereby regulating the catalytic activity of the metal-coordinated hypercrosslinked polymeric ionic liquids.
[0034] In the various embodiments of this invention, the performance of the catalyst is mainly compared by yield, which is quantitatively and qualitatively analyzed by a GC-8090-FID manufactured by Agilent Technologies.
[0035] Example 1:
[0036] Catalyst preparation process: Step 1: Take 10 mmol of triphenylphosphine monomer and 30 mmol of p-dibenzyl bromide and add them to a three-necked flask. Then slowly add 30 mL of 1,2-dichloroethane as a solvent. Heat in an oil bath at 45 °C for 4 h with stirring at 300 r / min. Then add 20 mmol of triphenylphosphine and 120 mmol of anhydrous ferric chloride. Wash the mixture multiple times with methanol and deionized water to obtain the intermediate hypercrosslinked polymeric ionic liquid, as shown in Figure 2.
[0037] Step 2: Metal-coordinated hypercrosslinked polymeric ionic liquid 1 was synthesized according to the molar ratio of triphenylphosphine in the polymeric ionic liquid, where the ratio of triphenylphosphine to ZnBr2 was 1:2. 1 g of the polymeric ionic liquid and 1.22 g of ZnBr2 were dissolved in 50 mL of tetrahydrofuran solution. The mixture was stirred at 200 r / min and heated in a constant-temperature oil bath at 30 °C under a nitrogen atmosphere for 24 h to carry out the coordination reaction. After the reaction, the tetrahydrofuran solvent was removed by vacuum filtration to obtain a solid catalyst. The polymer was then repeatedly washed with tetrahydrofuran, methanol, and deionized water to remove uncoordinated metals. Finally, the solid catalyst was dried in a vacuum drying oven at 70 °C until constant weight, yielding the desired product. Figure 1 The metal-coordinated hypercrosslinked polymeric ionic liquid.
[0038] Reaction process: In a 15ml sealed reactor, 1.74g of propylene oxide and 0.1g of metal-coordinated hypercrosslinked polymeric ionic liquid were added. The vent of the reactor was quickly closed, and CO2 at 1MPa was introduced into the system. The instrument was then heated to 90℃. After reaching the target temperature, the instrument parameters were adjusted to 250r / min and 1MPa, and the temperature was kept constant at 90℃ for 2h to obtain carbonate. The equipment was allowed to automatically cool down to room temperature. The yield of the catalyst was 96.2% as determined by chromatography.
[0039] Example 2
[0040] The only difference from Example 1 is that the ZnBr2 coordinating metal is replaced with ZnCl2, and the metal-coordinated hypercrosslinked polymeric ionic liquid has the structure shown in Formula 2.
[0041]
[0042] Example 2 yielded propylene carbonate in a yield of 47.3%.
[0043] Example 3
[0044] The only difference from Example 1 is that the ZnCl2 coordinating metal is replaced with ZnI2, and the metal-coordinated hypercrosslinked polymeric ionic liquid has the structure of Formula 3:
[0045]
[0046] Example 3 yielded propylene carbonate in a yield of 73.2%.
[0047] Example 4
[0048] The only difference from Example 1 is that the ZnI2 of the coordinating metal is replaced with NiBr2, and the metal-coordinated hypercrosslinked polymeric ionic liquid has the structure of Formula 4:
[0049]
[0050] Example 4 yielded propylene carbonate in a yield of 45.5%.
[0051] Example 5
[0052] The only difference from Example 1 is that the NiBr2 of the coordinating metal is replaced with CoBr2, and the metal-coordinated hypercrosslinked polymeric ionic liquid has the structure of Formula 5:
[0053]
[0054] Example 5 yielded propylene carbonate in a yield of 65.4%.
[0055] Example 6
[0056] The only difference from Example 1 is that the CoBr2 of the coordinating metal is replaced with MnBr2, and the metal-coordinated hypercrosslinked polymeric ionic liquid has the structure of Formula 6:
[0057]
[0058] Example 5 yielded propylene carbonate in a yield of 88.1%.
[0059] Example 7
[0060] The only difference from Example 1 is that the polymeric ionic liquid is not coordinated with a metal, and the metal-coordinated hypercrosslinked polymeric ionic liquid has a structure as shown in Formula 7:
[0061]
[0062] Example 5 yielded propylene carbonate in a yield of 43.6%.
[0063] Example 8
[0064] The only difference from Example 1 is that the temperature of the reactor is controlled at 70°C.
[0065] Example 1 yielded propylene carbonate in a yield of 91.2%.
[0066] Example 9
[0067] The only difference from Example 8 is that the reaction time in the reactor is controlled at 3 hours.
[0068] Example 9 yielded propylene carbonate in a yield of 96.2%.
[0069] After the cycloaddition reaction was completed, the upper ethylene carbonate solution was removed by separation. Then, the catalyst was washed with methanol (2×15ml), centrifuged, and the recovered catalyst was placed in an 80℃ vacuum drying oven for 24 hours to dry. The catalyst was then subjected to catalytic cycling again. The catalyst maintained stable catalytic activity after five cycles. The results are shown in Table 1.
[0070] Table 1 Catalyst Recycling Status
[0071] Catalyst cycle number 1 2 3 4 5 Yield (%) 96 93 93 94 93
[0072] In summary, this invention provides a simple and feasible heterogeneous catalyst synthesis strategy. The metal-coordinated hypercrosslinked polymeric ionic liquid catalyst exhibits excellent catalytic effects on the synthesis of carbonates from CO2 and epoxides. This invention features easy subsequent catalyst separation, low catalyst dosage, and strong thermal stability, and has potential for industrial application.
[0073] Although the present invention has been described in detail above with general description and specific embodiments, modifications or improvements can be made by those skilled in the art based on the present invention, and all such modifications or improvements fall within the scope of the present invention. Therefore, any modifications or improvements made without departing from the present invention are within the scope of protection claimed by the present invention.
Claims
1. A method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst, characterized in that, The metal-coordinated hypercrosslinked polymeric ionic liquid catalyst is synthesized in two steps. The first step involves the formation of a hypercrosslinked polymeric ionic liquid from triphenylphosphine and p-dibenzyl bromide through ionization and Friedel-Crafts alkylation reactions, which has the structure shown in Formula 1. The second step involves using triphenylphosphine, synthesized in Formula 1, as a coordination site to form a metal-coordinated hypercrosslinked polymeric ionic liquid with the structure shown in Formula 2. The catalyst is used to synthesize carbonates from CO2 and epoxides.
2. The method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst according to claim 1, characterized in that, Includes the following steps: Triphenylphosphine and solvent 1,2-dichloroethane were reacted under an inert atmosphere with the addition of p-dibenzyl bromide to generate a triphenylbenzylphosphine bromide ionic liquid. Then, anhydrous ferric chloride was added to rapidly polymerize the monomer via Friedel-Crafts alkylation to obtain the corresponding hypercrosslinked polymeric ionic liquid. A certain mass of the hypercrosslinked polymeric ionic liquid was then added to tetrahydrofuran for swelling for 4 hours. A metal salt was then added, and the triphenylphosphine in the hypercrosslinked polymeric ionic liquid coordinated with the metal salt to form a metal-coordinated hypercrosslinked polymeric ionic liquid. The liquid was then dried to constant weight under vacuum at 70°C to remove a small amount of solvent.
3. The method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst according to claim 1, characterized in that, The method for synthesizing carbonates is as follows: CO2 and epoxides were subjected to a cycloaddition reaction under the catalytic conditions of a metal-coordinated hypercrosslinked polymeric ionic liquid to obtain the corresponding carbonates.
4. The method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst according to claim 3, characterized in that, The cycloaddition reaction is carried out at a temperature of 30–110 °C.
5. The method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst according to claim 3, characterized in that, The reaction time for the cycloaddition reaction is 0.5 to 4 hours.
6. The method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst according to claim 3, characterized in that, The hypercrosslinked polymeric ionic liquid catalyst accounts for 0.01–0.08 mol% of the epoxide molars.
7. The method for preparing a metal-coordinated hypercrosslinked polymeric ionic liquid catalyst according to claim 3, characterized in that, The epoxide is any one of ethylene oxide, propylene oxide, butane oxide, epichlorohydrin, styrene oxide, cyclohexane oxide, and cyclopentane oxide. The preparation method includes the following steps: The epoxide and catalyst were placed in a sealed reactor, and the reactor temperature was maintained at a target temperature between 30°C and 110°C. CO2 gas was introduced into the reactor, and the pressure inside the reactor was maintained within 1 MPa. The reaction system underwent a cycloaddition reaction for 0.5–4 hours to obtain carbonates. The yield of the carbonates was 45.5%–97.6%.