An ionic MOFs catalyst of a positive electric property frame wrapping an anion guest
By introducing an ionic liquid onto sUiO-66-NH2 to prepare an ionic MOF catalyst with a positively charged framework encapsulating anionic guests, the problems of long reaction time and the need for additional co-catalysts in the prior art are solved, and the cycloaddition reaction of epoxides with CO2 is achieved with high efficiency to generate cyclic carbonates.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2025-01-22
- Publication Date
- 2026-07-31
AI Technical Summary
Existing MOF-based catalysts have long reaction times in the cycloaddition reaction of epoxides with CO2, and require the addition of additional co-catalysts and solvents.
Ionic MOFs catalysts, which encapsulate anionic guests with positively charged frameworks, were prepared by grafting ionic liquid chemical bonds onto sUiO-66-NH2 to create multifunctional heterogeneous catalysts for catalyzing the cycloaddition reaction of epoxides and CO2.
Under conditions without a co-catalyst, it significantly shortens the reaction time, improves catalytic activity and stability, and achieves high yield and selectivity. It is suitable for cycloaddition reactions of various epoxides with CO2.
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Figure CN119819374B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of composite material synthesis technology, specifically relating to an ionic MOF catalyst with a positively charged framework encapsulating anionic guests and its application in the catalytic epoxide-CO2 cycloaddition reaction to prepare cyclic carbonates. Background Technology
[0002] Carbon dioxide (CO2) is not only a major greenhouse gas but also an abundant, green, non-toxic, and renewable C1 feedstock. In recent years, excessive CO2 emissions have further exacerbated environmental problems such as global warming, glacial melting, and sea-level rise, posing greater challenges to the world's environment. Therefore, from both environmental protection and resource utilization perspectives, chemically fixing and recycling CO2 is a fundamental way to solve the greenhouse effect and a series of environmental problems; at the same time, it will also alleviate the problem of resource depletion.
[0003] To date, many valuable chemical raw materials have been synthesized using CO2 as a raw material, such as urea derivatives, methane, formic acid, amides, dimethyl carbonate, and cyclic carbonates. Among them, cyclic carbonates have the characteristics of high boiling point, low toxicity, and structural stability, and have wide applications in industrial production. Cyclic carbonates can be used as raw materials to synthesize polycarbonates, as solvents for separation in traditional chemical industries, as electrolyte solvents for lithium batteries, as raw materials for engineering plastics, as substitutes for toxic chemical reagents, and as intermediates in fine chemicals. Due to the wide application of cyclic carbonates in industry, the efficient preparation of cyclic carbonates through epoxide cycloaddition is one of the important pathways for CO2 utilization.
[0004] In recent years, MOF-based catalysts for the catalytic reaction of epoxides and CO2 to form cyclic carbonates under co-catalyst-free conditions have been extensively studied and can be mainly divided into three categories. The first category consists of MOFs containing Lewis basic functional groups (such as -NH2, -NH, pyridine, etc.), which are generally contained in pre-designed organic ligands. For example, the Dae-Won Park group synthesized a MOF catalyst—UMCM-1-NH2—using the organic ligand 2-aminoterephthalic acid containing -NH2. This catalyst utilizes the basic site -NH2 to activate CO2 and catalyze the cycloaddition reaction of propylene oxide and CO2 under co-catalyst-free conditions. Under the conditions of a reaction temperature of 120 °C, a CO2 pressure of 1.2 MPa, and a reaction time of 24 h, the conversion rate of propylene oxide was 95%, and the selectivity for propylene carbonate was 95%. The second type involves encapsulating ionic liquids or ionic polymers within the pores of neutral MOFs. This utilizes the exposed Lewis acid sites in the MOFs and the nucleophilic sites in the ionic liquid to induce a cycloaddition reaction of epoxides and CO2, preparing cyclic carbonates. For example, Jiang Hailong's research group prepared a composite material encapsulating a polyionic liquid—polyILs@MIL-101—within the pores of neutral MOFs. This polyionic liquid contains the nucleophilic anion Br. - This composite material can promote the activation of epoxides, avoiding the need for additional co-catalysts. When used to catalyze the cycloaddition reaction of epichlorohydrin and CO2, the yield of chloropropylene carbonate was 94% after 24 h at a reaction temperature of 50 °C and a CO2 pressure of 0.1 MPa. However, both of these MOF-based catalysts typically require long reaction times for the cycloaddition reaction of epoxides and CO2.
[0005] The third type is ionic MOFs (IMOFs), which are positively charged frameworks encapsulating anionic guests. These MOFs have cationic groups covalently bonded to their organic ligands, giving the framework a net positive charge. The pores contain counter anions (nucleophilic anions). IMOFs with positively charged frameworks encapsulating anionic guests contain metal Lewis acid centers, which can activate epoxides by coordinating with the oxygen atoms of the epoxides. The nucleophilic anions within the pores can attack the epoxides, promoting ring-opening. Furthermore, the positively charged organic ligands can be modified to activate CO2 or epoxides, enabling the catalytic epoxide-CO2 cycloaddition reaction to prepare cyclic carbonates under co-catalyst-free conditions. This makes them a multifunctional composite catalyst. Summary of the Invention
[0006] The purpose of this invention is to provide an ionic MOF catalyst with a positively charged framework encapsulating anionic guests, and to apply it to the catalytic epoxide-CO2 cycloaddition reaction to prepare cyclic carbonates. This invention grafts an ionic liquid onto sUiO-66-NH2 via chemical bonds to prepare a multifunctional heterogeneous catalyst. When used to catalyze the epoxide-CO2 cycloaddition reaction to prepare cyclic carbonates, this catalyst exhibits high activity and stability without the need for a co-catalyst, effectively shortens the reaction time, and is both multifunctional and economical.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: An ionic MOF catalyst with a positively charged framework encapsulating an anionic guest is prepared by the following steps: 1) Dissolve 2-aminoterephthalic acid and ZrCl4 in DMF, then add acetic acid, sonicate for 30 min, and pour the mixture into a hydrothermal synthesis vessel for hydrothermal reaction; after the reaction is completed, cool to room temperature, immediately centrifuge the resulting pink solution and wash with organic solvent, dry to obtain sUiO-66-NH2; 2) HBr was slowly added dropwise to triethylenediamine (DABCO), and the mixture was stirred at room temperature for 12 h. After dehydration and vacuum drying, [DABCO][Br] was obtained. 3) Grind the sUiO-66-NH2 obtained in step 1) and the [DABCO][Br] obtained in step 2) into powder, add toluene to dissolve, and stir the reaction under a nitrogen atmosphere; after the reaction is completed, centrifuge, wash with organic solvent, remove water, and vacuum dry to obtain the ionic MOF catalyst [D][Br]@sUiO-66-NH2 with the positively charged framework encapsulating the anionic guest.
[0008] Furthermore, the molar ratio of 2-aminoterephthalic acid and ZrCl4 used in step 1) is 1:2.
[0009] Furthermore, the molar ratio of 2-aminoterephthalic acid to acetic acid used in step 1) is 1:0.05.
[0010] Furthermore, the hydrothermal reaction in step 1) is carried out at a temperature of 110-130 °C for a time of 72-74 h.
[0011] Furthermore, the drying temperature in step 1) is 50-70 °C and the time is 12-14 h.
[0012] Furthermore, the mass ratio of triethylenediamine to HBr used in step 2) is 1:1.
[0013] Furthermore, the vacuum drying temperature in step 2) is 100-120 °C, and the time is 10-15 h.
[0014] Furthermore, in step 3), the mass ratio of [DABCO][Br] and sUiO-66-NH2 used is 1:1.
[0015] Furthermore, the temperature of the stirring reaction in step 3) is 90-100 °C, and the time is 12-14 h.
[0016] Furthermore, the vacuum drying temperature in step 3) is 90-110 °C, and the time is 12-14 h.
[0017] The resulting ionic MOF catalysts with positively charged frameworks encapsulating anionic guests can be used to catalyze the cycloaddition reaction of epoxides with CO2 to prepare cyclic carbonates.
[0018] Furthermore, the epoxide includes any one of styrene oxide, epichlorohydrin, propylene oxide, and butane oxide.
[0019] Furthermore, the cycloaddition reaction is carried out at a temperature of 100-120 °C, a pressure of 1-1.2 MPa, and a time of 12-14 h.
[0020] The styrene oxide molecule contains a benzene ring, which has significant steric hindrance, hindering the approach and reaction of CO2 with the epoxy group. This increases the activation energy and makes the reaction more difficult. Simultaneously, because the benzene ring is an electron-rich group with an electron-donating conjugation effect, the electron cloud density of the epoxy group in styrene oxide increases, reducing its electrophilicity and thus hindering the nucleophile CO2 attack. Therefore, the cycloaddition reaction of styrene oxide with CO2 has different characteristics from cycloaddition reactions in other systems, and is more challenging. This invention employs a unique material structure design and composition improvement methods to provide an ionic MOF catalyst. This catalyst exhibits two significant characteristics: first, it achieves a considerable yield in the cycloaddition reaction of styrene oxide with CO2 to prepare cyclic carbonates, significantly outperforming the material performance of existing technologies; second, this catalyst has broad applicability to the reactions of various epoxides with CO2, effectively promoting the reaction and generating the corresponding cyclic carbonates.
[0021] The advantages and effects of this invention are as follows: 1. This invention provides an ionic MOF catalyst in which anionic guests are encapsulated in a positively charged framework. By introducing ionic liquids into the MOF structure, it enables the MOF to simultaneously possess CO2 adsorption and activation capabilities, as well as the ability to promote the ring-opening of epoxides, thereby obtaining a multifunctional heterogeneous catalyst.
[0022] 2. When the ionic MOF catalyst prepared by this invention is applied to the catalytic cycloaddition reaction of epoxides with CO2 to prepare cyclic carbonates, no additional co-catalyst or solvent is required. Moreover, the catalyst has a certain degree of universality. When catalyzing the cycloaddition reaction of various epoxides with CO2, the conversion rate of epoxides is 100% and the selectivity of cyclic carbonates is greater than 80%. Attached Figure Description
[0023] Figure 1 The XRD comparison spectra of samples sUiO-66-NH2 and [D][Br]@sUiO-66-NH2 prepared in Example 1 are shown.
[0024] Figure 2 The SEM comparison spectra of samples sUiO-66-NH2 (a) and [D][Br]@sUiO-66-NH2 (b) prepared in Example 1 are shown. Detailed Implementation
[0025] An ionic MOF catalyst with a positively charged framework encapsulating an anionic guest is prepared by the following steps: 1) Dissolve 2-aminoterephthalic acid and ZrCl4 in DMF at a molar ratio of 1:1. Then add acetic acid at a molar ratio of 0.05:1 to 2-aminoterephthalic acid. After sonication for 30 min, pour the mixture into a hydrothermal synthesis reactor and react in a forced-air drying oven at 110-130 ℃ for 72-74 h. After the reaction is complete, cool to room temperature and immediately centrifuge the resulting pink solution and wash with an organic solvent (the product is pink at this time; if the processing time is too long, the product will be light yellow and unusable). Then dry in a normal oven at 50-70 ℃ for 12-14 h to obtain sUiO-66-NH2. 2) Weigh triethylenediamine (DABCO) into a beaker, and then slowly add hydrogen bromide (HBr) dropwise in a fume hood at a mass ratio of 1:1. Stir at room temperature for 12 h, then place in a regular oven to remove water, and then place in a vacuum oven to dry at 100-120 ℃ for 10-15 h to obtain [DABCO][Br]. 3) Grind the sUiO-66-NH2 obtained in step 1) and the [DABCO][Br] obtained in step 2) into powder, place them in a round-bottom flask at a mass ratio of 1:1, add toluene to dissolve, and stir the mixture in an oil bath at 90-100℃ for 12-14 h under a nitrogen atmosphere. After the reaction is completed, centrifuge the obtained sample to separate the solvent, wash it with an organic solvent, place it in a normal oven to remove water, and finally vacuum dry it in a vacuum drying oven at 90-110 ℃ for 12-14 h to obtain the ionic MOF catalyst [D][Br]@sUiO-66-NH2 with a positively charged framework encapsulating anionic guests.
[0026] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto. Example
[0027] 1) 2-Aminoterephthalic acid (0.181 g, 1.0 mmol) and ZrCl4 (0.466 g, 2.0 mmol) were dissolved in DMF (60 mL), followed by the addition of acetic acid (3.0 g, 0.05 mmol). After sonication for 30 minutes, the mixture was poured into a 100 mL hydrothermal synthesis vessel and heated at 120 °C for 72 h in a forced-air drying oven. Subsequently, the hydrothermal synthesis vessel was cooled to room temperature, and the resulting pink solution was centrifuged and washed twice each with DMF and methanol, and then dried at 60 °C for 24 h to obtain the Zr-based MOF material sUiO-66-NH2.
[0028] 2) Weigh DABCO and HBr in a molar ratio of 1:1. Then place DABCO in a beaker, slowly add HBr dropwise in a fume hood, stir the resulting mixture at room temperature for 12 hours, remove water in a regular oven, and then dry in a vacuum oven at 100°C for 12 hours to obtain the ionic liquid [DABCO][Br].
[0029] 3) Grind 1 g of [DABCO][Br] and 1 g of sUiO-66-NH2 into powder and place them in a 100 ml round-bottom flask. Add 50 ml of toluene solvent and stir in a 95 ℃ oil bath for 12 h. After the reaction, centrifuge the obtained sample to separate the solvent, wash twice with DMF and methanol respectively, and then place it in a normal oven to remove water. Finally, dry it in a 100 ℃ vacuum drying oven for 12 h to obtain the composite material [D][Br]@sUiO-66-NH2.
[0030] Figure 1 The XRD comparison spectra of sUiO-66-NH2 and [D][Br]@sUiO-66-NH2 prepared in this embodiment are shown. As can be seen from the figure, the crystal form of sUiO-66-NH2 did not change after the ionic liquid [DABCO][Br] was immobilized on it, indicating that the introduction of [DABCO][Br] does not disrupt the crystal structure of sUiO-66-NH2.
[0031] Figure 2The SEM comparison spectra of sUiO-66-NH2 and [D][Br]@sUiO-66-NH2 prepared in this embodiment are shown in the figure. As can be seen from the figure, the microstructure of sUiO-66-NH2 is a regular octahedron (a), and the octahedron shape is still present after the introduction of [DABCO][Br] (b), indicating that the introduction of [DABCO][Br] does not destroy the framework structure of sUiO-66-NH2.
[0032] Application Example 1 At room temperature, 2 mmol of epichlorohydrin and 5 wt.% of [D][Br]@sUiO-66-NH2 prepared in Example 1 were weighed into a parallel high-pressure reactor equipped with a magnetic stirrer. The reactor was carefully sealed and purged five times with CO2 gas to remove residual air and atmospheric moisture. Then, 1.0 MPa of CO2 was introduced, and the temperature was set to 100 °C, the reaction time to 12 h, and the rotation speed to 300 rpm. After the reaction was complete, the reactor was allowed to cool to room temperature, and excess gas was slowly released until the pressure inside the reactor returned to normal. Quantitative analysis was performed using gas chromatography after the reaction was complete.
[0033] The results showed that, under the above reaction conditions, the conversion rate of epichlorohydrin was 100% and the yield of chloropropylene carbonate was 95.17%.
[0034] Application Example 2 At room temperature, 2 mmol of propylene oxide and 5 wt.% of [D][Br]@sUiO-66-NH2 prepared in Example 1 were weighed into a parallel high-pressure reactor equipped with a magnetic stirrer. The reactor was carefully sealed and purged five times with CO2 gas to remove residual air and atmospheric moisture. Then, 1.1 MPa of CO2 was introduced, and the temperature was set to 110 °C, the reaction time to 14 h, and the rotation speed to 400 rpm. After the reaction was completed, the reactor was allowed to cool to room temperature, and excess gas was slowly released until the pressure inside the reactor returned to normal. Quantitative analysis was performed using gas chromatography after the reaction was completed.
[0035] The results showed that, under the above reaction conditions, the conversion rate of propylene oxide was 100% and the yield of propylene carbonate was 98.20%.
[0036] Application Example 3 At room temperature, 2 mmol of epoxide and 5 wt.% of [D][Br]@sUiO-66-NH2 prepared in Example 1 were weighed into a parallel high-pressure reactor equipped with a magnetic stirrer. The reactor was carefully sealed and purged five times with CO2 gas to remove residual air and atmospheric moisture. Then, 1.2 MPa of CO2 was introduced, and the temperature was set to 120 °C, the reaction time to 13 h, and the rotation speed to 400 rpm. After the reaction was complete, the reactor was allowed to cool to room temperature, and excess gas was slowly released until the pressure inside the reactor returned to normal. Quantitative analysis was performed using gas chromatography after the reaction was complete.
[0037] The results showed that, under the above reaction conditions, the conversion rate of epoxide was 100% and the yield of butene carbonate was 92.32%.
[0038] Application Example 4 At room temperature, 2 mmol of styrene oxide and 5 wt.% of [D][Br]@sUiO-66-NH2 prepared in Example 1 were weighed into a parallel high-pressure reactor equipped with a magnetic stirrer. The reactor was carefully sealed and purged five times with CO2 gas to remove residual air and atmospheric moisture. Then, 1.2 MPa of CO2 was introduced, and the temperature was set to 100 °C, the reaction time to 14 h, and the rotation speed to 400 rpm. After the reaction was complete, the reactor was allowed to cool to room temperature, and excess gas was slowly released until atmospheric pressure was restored. Quantitative analysis was performed using gas chromatography after the reaction.
[0039] The results showed that, under the above reaction conditions, the conversion rate of styrene oxide was 100% and the yield of styrene cyclic carbonate was 80.55%.
[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. An ionic MOFs catalyst of positive electric property frame wrapping anion guest, characterized in that: Its preparation includes the following steps: 1) Dissolve 2-aminoterephthalic acid and ZrCl4 in DMF, then add acetic acid, sonicate for 30 min, and pour the mixture into a hydrothermal synthesis vessel for hydrothermal reaction; after the reaction is completed, cool to room temperature, immediately centrifuge the resulting pink solution and wash with organic solvent, dry to obtain sUiO-66-NH2; 2) HBr was slowly added dropwise to triethylenediamine, and the mixture was stirred at room temperature for 12 h. After dehydration and vacuum drying, [DABCO][Br] was obtained. 3) Grind the sUiO-66-NH2 obtained in step 1) and the [DABCO][Br] obtained in step 2) into powder, add toluene to dissolve, and stir the reaction under a nitrogen atmosphere; after the reaction is completed, centrifuge, wash with organic solvent, remove water, and vacuum dry to obtain the ionic MOF catalyst with the positively charged framework encapsulating the anionic guest. The mass ratio of [DABCO][Br] and sUiO-66-NH2 used in step 3) is 1:
1.
2. The positively electropositive framework encapsulating anionic guest ionic MOFs catalyst according to claim 1, characterized in that: The molar ratio of 2-aminoterephthalic acid and ZrCl4 used in step 1) is 1:
2.
3. The positively electropositive framework encapsulating anionic guest ionic MOFs catalyst according to claim 1, characterized in that: The molar ratio of 2-aminoterephthalic acid to acetic acid used in step 1) is 1:0.
05.
4. The ionic MOF catalyst with a positively charged framework encapsulating anionic guests according to claim 1, characterized in that: The hydrothermal reaction in step 1) is carried out at a temperature of 110-130 °C for 72-74 h.
5. The ionic MOF catalyst with a positively charged framework encapsulating anionic guests according to claim 1, characterized in that: The mass ratio of triethylenediamine and HBr used in step 2) is 1:
1.
6. The ionic MOF catalyst with a positively charged framework encapsulating anionic guests according to claim 1, characterized in that: The stirring reaction in step 3) is carried out at a temperature of 90-100 ℃ for 12-14 h.
7. The application of an ionic MOF catalyst with a positively charged framework encapsulating anionic guest as described in claim 1 in the catalytic cycloaddition reaction of epoxides with CO2 to prepare cyclic carbonates.
8. The application according to claim 7, characterized in that: The epoxide includes any one of styrene oxide, epichlorohydrin, propylene oxide, and butane oxide.
9. The application according to claim 7, characterized in that: The cycloaddition reaction is carried out at a temperature of 100-120 °C, a pressure of 1-1.2 MPa, and a time of 12-14 h.