Use of a metal ion-doped graphene oxide film material in catalyzing synthesis of cyclic carbonates from CO2

Abstract

The application provides a use of a metal ion doped aminated graphene oxide membrane material in catalyzing synthesis of cyclic carbonates from CO2. The metal ion doped aminated graphene oxide membrane material has both acidic catalytic sites and basic catalytic sites, and the two-dimensional interlayer channel of the metal ion doped aminated graphene oxide membrane material also has a confinement effect. In the process of catalyzing the ring addition reaction of CO2 / epoxide, the epoxide molecules entering the two-dimensional interlayer confinement channel of the metal ion doped aminated graphene oxide membrane material are efficiently opened and reacted with CO2 under the combined action of organic amine molecules and metal ions, and finally, the cyclic carbonates are efficiently synthesized from CO2 under the conditions of room temperature and low pressure (greater than 0.1 MPa and less than or equal to 1 MPa), with a reaction time of less than or equal to 5 min and an epoxide conversion rate of 75% to 100%.

Description

Technical Field

[0001] This invention belongs to the field of membrane catalysis technology, and mainly relates to the use of a metal ion-doped aminated graphene oxide membrane material in the rapid and efficient catalysis of CO2 / epoxide cycloaddition reaction to synthesize cyclic carbonates at room temperature. Background Technology

[0002] Excessive CO2 emissions from human activities are widely recognized as a major cause of global warming and a range of environmental problems. Capturing, utilizing, and storing carbon dioxide is widely accepted globally as an effective means of carbon reduction. However, the stable chemical properties of CO2 pose a significant challenge to achieving efficient CO2 utilization under mild conditions.

[0003] Carbonates are compounds in which the hydroxyl hydrogen in a carbonic acid molecule is partially or completely replaced by an alkyl group. Cyclic carbonates, due to their high dipole moment, good dielectric properties, and low toxicity, are used in the chemical industry as solvents, battery electrolytes, polycarbonate monomers, and also as intermediates for other important compounds, such as pyrimidines and carbamates.

[0004] Traditional cyclic carbonate production processes using glycols and phosgene as raw materials are gradually being phased out due to their low economic efficiency and environmental unfriendliness. In contrast, the cycloaddition reaction method using CO2 and epoxides achieves 100% atom utilization, aligning with the principles of "green chemistry" and meeting the requirements of the "sustainable development strategy." The development of novel, highly efficient catalysts is a key research focus in the CO2 cycloaddition reaction process for synthesizing cyclic carbonates. Researchers have successfully developed numerous catalysts of various types for the cycloaddition reaction of CO2 and epoxides, such as porous organic polymers (POPs), ionic liquids (ILs), metal-organic frameworks (MOFs), and molecular sieves. However, while these reported catalysts can achieve high conversion rates of epoxides, they still suffer from drawbacks such as high required reaction temperatures (>100℃), high required CO2 pressures (>1MPa), and long reaction times (>72h). These drawbacks represent significant obstacles to the widespread adoption of the CO2 cycloaddition reaction method. Therefore, finding a rapid and efficient way to synthesize cyclic carbonates from CO2 under low-temperature and low-pressure conditions is of great economic and environmental significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide the application of a metal ion-doped aminated graphene oxide film material in the catalytic synthesis of cyclic carbonates from CO2. The metal ion-doped aminated graphene oxide film material is a multilayered graphene oxide (GO) film material with organic amine molecules and metal ions loaded on both the surface and between layers. This metal ion-doped aminated graphene oxide film material simultaneously possesses both acidic and basic catalytic sites, and the two-dimensional interlayer channels of the metal ion-doped aminated graphene oxide film material also have a confinement effect. In the catalytic CO2 / epoxide cycloaddition reaction, a portion of CO2 dissolves in the reaction solution and participates in the CO2 / epoxide cycloaddition reaction as a reactant. Another portion of CO2 acts as a driving force, propelling the reaction solution through the metal ion-doped aminated graphene oxide membrane material. Epoxide molecules entering the two-dimensional interlayer confined channels of the metal ion-doped aminated graphene oxide membrane material undergo efficient ring-opening and react with CO2 under the combined action of organic amine molecules and metal ions. Ultimately, under room temperature and low pressure (greater than 0.1 MPa and less than or equal to 1 MPa (preferably greater than 0.1 MPa and less than or equal to 0.5 MPa) conditions, CO2 is efficiently synthesized (reaction time ≤ 5 min, epoxy conversion rate 75%-100%) to form cyclic carbonates.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The use of a metal ion-doped aminated graphene oxide film material in the catalytic synthesis of cyclic carbonates from CO2.

[0008] According to an embodiment of the present invention, the metal ion-doped aminated graphene oxide film material is used in the rapid catalytic synthesis of cyclic carbonates from CO2 at room temperature.

[0009] According to embodiments of the present invention, the metal ion-doped aminated graphene oxide film material is used in the rapid catalytic CO2 / epoxide cycloaddition reaction at room temperature to synthesize cyclic carbonates.

[0010] According to an embodiment of the present invention, the metal ion-doped aminated graphene oxide film material is used in the rapid and efficient catalytic synthesis of cyclic carbonates from CO2 at room temperature.

[0011] According to embodiments of the present invention, the metal ion-doped aminated graphene oxide film material is used in the rapid and efficient catalytic cycloaddition reaction of CO2 / epoxide compounds at room temperature to synthesize cyclic carbonates.

[0012] According to an embodiment of the present invention, the room temperature refers to a temperature range of 20-30°C, such as 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C.

[0013] According to an embodiment of the present invention, "rapid" refers to a reaction time of 30-300 seconds, such as 120-180 seconds.

[0014] According to an embodiment of the present invention, the high efficiency refers to a conversion rate of 75%-100% for the epoxy compound.

[0015] According to an embodiment of the present invention, the metal ion-doped aminated graphene oxide film material has a layered structure formed by stacking metal ion-doped aminated graphene oxide nanosheets together.

[0016] According to an embodiment of the present invention, the metal ion-doped aminated graphene oxide nanosheets include graphene oxide nanosheets, organic amines, and metal ions; the organic amines are chemically modified on the surface and interlayer of the graphene oxide nanosheets; and the metal ions are doped onto the surface and interlayer of the graphene oxide nanosheets.

[0017] According to an embodiment of the present invention, the metal ion-doped aminated graphene oxide film material comprises graphene oxide, organic amine, and metal ions; the organic amine is chemically modified on the surface and interlayer of the graphene oxide; and the metal ions are doped onto the surface and interlayer of the graphene oxide.

[0018] According to embodiments of the present invention, the thickness of the metal ion-doped aminated graphene oxide film material is 0.1-5 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm; by controlling the film thickness, the retention time of reactant molecules in the two-dimensional interlayer confined channels of the metal ion-doped aminated graphene oxide film material can be controlled, thereby optimizing its catalytic performance. Studies have found that the reactants have too short a retention time in excessively thin metal ion-doped aminated graphene oxide films (thickness less than 0.1 μm), resulting in an inability to achieve high conversion rates. Excessively thick metal ion-doped aminated graphene oxide films (thickness greater than 5 μm) significantly reduce the flow rate of the reaction solution and increase the preparation cost of the film material, resulting in a significant decrease in the efficiency of catalytic CO2 synthesis of cyclic carbonates.

[0019] According to an embodiment of the present invention, the interlayer spacing of the metal ion-doped aminated graphene oxide film material is 1-2 nm, for example, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.9 nm or 2 nm.

[0020] According to embodiments of the present invention, the mass of metal ions in the metal ion-doped aminated graphene oxide film material accounts for 0.01-5 wt% of the total mass of the film material, for example, 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, and 5 wt%. When the mass of metal ions in the metal ion-doped aminated graphene oxide film material is less than 0.01 wt% of the total mass of the film material, the content of metal active centers in the film material is low, and the catalytic effect on the CO2 / epoxide cycloaddition reaction is not obvious. When the mass of metal ions in the metal ion-doped aminated graphene oxide film material is greater than 5 wt% of the total mass of the film material, the interaction between graphene oxide nanosheets and metal ions is enhanced, affecting the uniformity and structural stability of the metal ion-doped aminated graphene oxide film material.

[0021] According to embodiments of the present invention, the organic amine in the metal ion-doped aminated graphene oxide membrane material accounts for 5-50 wt% of the total mass of the membrane material, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%. When the organic amine in the metal ion-doped aminated graphene oxide membrane material accounts for less than 5 wt% of the total mass of the membrane material, the content of basic catalytic sites in the membrane material is relatively low, resulting in insufficient catalytic effect on the CO2 / epoxide cycloaddition reaction.

[0022] According to embodiments of the present invention, the metal ion is selected from at least one transition metal ion; exemplarily, the metal ion is selected from Fe. 3+ Co 2+ and Ni 2+ At least one of them, preferably Co 2+ .

[0023] According to an embodiment of the present invention, the organic amine is selected from at least one of triethylenetetramine, tetraethylenepentamine, tri(2-aminoethyl)amine, 4-aminomethylpyridine, 1,5-diaminomethylpyridine, etc.

[0024] According to an embodiment of the present invention, the metal ion-doped aminated graphene oxide film material is prepared by the following method:

[0025] (1) The graphene oxide dispersion, organic amine and activator were mixed and reacted, followed by dialysis and ultrasonic treatment to prepare an aminated graphene oxide dispersion.

[0026] (2) Add metal salt to aminated graphene oxide dispersion and mix ultrasonically to obtain metal ion doped aminated graphene oxide dispersion.

[0027] (3) The metal ion-doped aminated graphene oxide dispersion from step (2) is assembled into a metal ion-doped aminated graphene oxide membrane by vacuum filtration and then subjected to constant temperature and humidity static treatment to obtain the metal ion-doped aminated graphene oxide membrane material.

[0028] According to an embodiment of the present invention, in step (1), the activator is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0029] According to an embodiment of the present invention, in step (1), the organic amine is selected from at least one of triethylenetetramine, tetraethylenepentamine, tri(2-aminoethyl)amine, 4-aminomethylpyridine, 1,5-diaminomethylpyridine, etc.

[0030] According to an embodiment of the present invention, in step (1), the graphene oxide dispersion is an aqueous dispersion of graphene oxide. The concentration of the graphene oxide dispersion is 0.5-2 mg / mL, for example, 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL or 2 mg / mL.

[0031] According to an embodiment of the present invention, in step (1), the graphene oxide is a single-layer graphene oxide nanosheet, and the diameter of the single-layer graphene oxide nanosheet is >500nm.

[0032] According to an embodiment of the present invention, in step (1), the mass ratio of graphene oxide to organic amine is 1:12-1:50, for example, 1:12, 1:15, 1:18, 1:20, 1:22, 1:25, 1:28, 1:30, 1:32, 1:35, 1:38, 1:40, 1:42, 1:45, 1:48, or 1:50. By changing the mass ratio of graphene oxide to organic amine, the mass percentage of organic amine in the metal ion-doped aminated graphene oxide film material can be controlled, thereby controlling the catalytic performance of the metal ion-doped aminated graphene oxide film material.

[0033] According to an embodiment of the present invention, in step (1), the mass ratio of graphene oxide to activator is 1:8-1:25, for example, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:18, 1:20, 1:22, 1:24 or 1:25.

[0034] According to an embodiment of the present invention, in step (1), the reaction temperature is 20-40°C, the reaction time is 6-18 hours, and the reaction is carried out under stirring conditions.

[0035] According to an embodiment of the present invention, in step (1), the dialysis treatment involves pouring the reacted dispersion into a dialysis bag (the dialysis bag has a molecular weight cutoff of 4500-20000 g / mol) and dialyzing it with ultrapure water for more than 24 hours to remove unreacted small molecule impurities and obtain a pure aminated graphene oxide dispersion. For example, 20 mL of the reacted dispersion is poured into a dialysis bag with a molecular weight cutoff of M = 14000 g / mol, sealed, and placed in 2 L of ultrapure water. Stirring is then started, and the water is changed every 12 hours for a total of 8 changes.

[0036] According to an embodiment of the present invention, in step (1), the ultrasonic treatment time is 10 min to 120 min, and the ultrasonic treatment power is 100 to 300 W, for example, 150 W.

[0037] According to an embodiment of the present invention, in step (1), the concentration of the aminated graphene oxide dispersion is 0.5-1.5 mg / mL, that is, 1 mL of the aminated graphene oxide dispersion contains 0.5-1.5 mg of aminated graphene oxide; exemplaryly, the concentration of the aminated graphene oxide dispersion is 0.5 mg / mL, 0.6 mg / mL, 0.7 mg / mL, 0.8 mg / mL, 0.9 mg / mL, 1.0 mg / mL, 1.1 mg / mL, 1.2 mg / mL, 1.3 mg / mL, 1.4 mg / mL or 1.5 mg / mL.

[0038] According to an embodiment of the present invention, in step (1), the surface of graphene oxide has carboxyl functional groups and epoxy functional groups. Using a chemical modification method, under the condition of the presence of an activator, the amino group in the organic amine molecule reacts with the carboxyl functional groups and epoxy functional groups on the surface of graphene oxide, thereby modifying the surface of graphene oxide nanosheets with catalytic activity, thus obtaining a dispersion containing aminated graphene oxide nanosheets.

[0039] According to an embodiment of the present invention, in step (1), for example, 20 mL of graphene oxide dispersion with a concentration of 2 mg / mL is taken, 600 μL of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide is added, and the mixture is stirred for 1 hour. Then, 1 mL of organic amine is added, and the mixture is stirred for 12 hours. After that, the mixture is dialyzed to remove small molecules. The dialysate is taken out and diluted with water to 180 mL. It is then sonicated at 150 W for 10 min. After sonication, the dispersion is transferred to a reagent bottle and stored in a sealed container at room temperature.

[0040] According to an embodiment of the present invention, in step (2), by changing the concentration of the aminated graphene oxide dispersion and the mass ratio of the aminated graphene oxide dispersion to the metal salt, the mass ratio of metal ions in the metal ion-doped aminated graphene oxide film material can be controlled, thereby controlling the catalytic performance of the metal ion-doped aminated graphene oxide film material.

[0041] According to an embodiment of the present invention, in step (2), by adding a metal salt to the aminated graphene oxide dispersion and then performing ultrasonic mixing treatment, the aminated graphene oxide and metal ions can fully interact, thereby doping the metal ions onto the surface and interlayer of the aminated graphene oxide, and at the same time obtaining a more uniformly dispersed aminated graphene oxide dispersion doped with metal ions.

[0042] According to an embodiment of the present invention, in step (2), the metal salt is selected from at least one transition metal salt; exemplarily, the cation in the metal salt is selected from Fe. 2+ Co 2+ Ni 2+ etc., preferably Co 2+ The anion in the metal salt is selected from F. - Cl - ,Br - I - NO3 - NO2 - CH3COO - etc., preferably Cl - .

[0043] According to an embodiment of the present invention, in step (2), the molar mass ratio of the metal salt to the aminated graphene oxide is 2-30 μmol / 2.25-6.75 mg, that is, 2-30 μmol of metal salt is added to every 2.25-6.75 mg of aminated graphene oxide; preferably, the molar mass ratio of the metal salt to the aminated graphene oxide is 12-16 μmol / 2.25-6.75 mg.

[0044] According to an embodiment of the present invention, in step (2), the molar volume ratio of the metal salt to the aminated graphene oxide dispersion is 2-30 μmol / 4.5 mL, that is, 2-30 μmol of metal salt is added to every 4.5 mL of aminated graphene oxide dispersion; preferably, the molar volume ratio of the metal salt to the aminated graphene oxide dispersion is 12-16 μmol / 4.5 mL. Excessive addition of metal salt will enhance the interaction between aminated graphene oxide and metal ions, making it impossible to uniformly disperse in water by ultrasound, and may also lead to aggregation, affecting the uniformity and structural stability of the subsequently prepared metal ion-doped aminated graphene oxide membrane material; insufficient addition of metal salt will reduce the catalytic performance of the metal ion-doped aminated graphene oxide membrane material, making it impossible to obtain a high conversion rate.

[0045] According to an embodiment of the present invention, in step (2), the ultrasonic mixing time is 5-15 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min; the ultrasonic mixing power is 100-500 W, for example, 100 W, 150 W, 200 W, 250 W, 300 W, 350 W, 400 W, 450 W, or 500 W. Under these conditions, ultrasonic mixing can achieve a more uniformly dispersed metal ion-doped aminated graphene oxide dispersion without damaging the structure of the metal ion-doped aminated graphene oxide.

[0046] According to an embodiment of the present invention, in step (3), the thickness of the metal ion-doped aminated graphene oxide membrane material can be adjusted by adjusting the concentration of the metal ion-doped aminated graphene oxide dispersion or the filtration volume. For example, the higher the concentration of the metal ion-doped aminated graphene oxide dispersion or the filtration volume, the thicker the metal ion-doped aminated graphene oxide membrane material prepared.

[0047] According to an embodiment of the present invention, step (3) specifically includes the following steps:

[0048] 31) Lay a porous substrate in the filter cup of the vacuum filtration device;

[0049] 32) Add the metal ion-doped aminated graphene oxide dispersion from step (2) into a filter cup that is matched with a vacuum filtration device, start the vacuum pump, and perform vacuum filtration with a vacuum degree of 1-5 Pa. Use the vacuum pressure difference to assemble the metal ion-doped aminated graphene oxide nanosheets layer by layer on the porous substrate to prepare a metal ion-doped aminated graphene oxide membrane material.

[0050] According to an embodiment of the present invention, the porous substrate may be made of organic filter membranes such as nylon 66, polyvinylidene fluoride, and polytetrafluoroethylene.

[0051] According to an embodiment of the present invention, the pore size of the porous substrate is 0.1-0.3 μm, for example, 0.22 μm.

[0052] According to an embodiment of the present invention, a membrane of a certain thickness is prepared on a porous substrate by vacuum filtration, which is formed by stacking multiple monolayer metal ion-doped aminated graphene oxide nanosheets.

[0053] According to an embodiment of the present invention, as filtration proceeds, the metal ion-doped aminated graphene oxide (preferably metal ion-doped aminated graphene oxide nanosheets) in the metal ion-doped aminated graphene oxide dispersion assembles into a layered structure under the action of water flow. Once filtration is completed, the metal ion-doped aminated graphene oxide membrane material is obtained.

[0054] According to an embodiment of the present invention, in step (3), the constant temperature and humidity settling treatment is, for example, settling under constant temperature and humidity conditions for a period of time; exemplaryly, the constant temperature and humidity settling treatment is carried out in a constant temperature and humidity chamber. Exemplarily, the constant temperature and humidity settling treatment is set at 20-30℃ and 10-20%RH for 12-24 hours. The constant temperature and humidity settling treatment can remove free water from the metal ion-doped aminated graphene oxide membrane material after filtration.

[0055] According to an embodiment of the present invention, the method for catalytically synthesizing cyclic carbonates from CO2 includes the following steps:

[0056] a) Mix the epoxy compound, the co-catalyst, and an organic solvent, which may or may not be added, to obtain a reaction solution;

[0057] b) At room temperature, place the metal ion-doped aminated graphene oxide film material at the bottom of the pressurizing device, add the reaction solution from step a) into the pressurizing device and place it above the metal ion-doped aminated graphene oxide film material, introduce CO2 to replace the air in the pressurizing device, and then continue to introduce CO2 to increase the pressure in the pressurizing device. The reaction solution passes through the metal ion-doped aminated graphene oxide film material under the pressure of CO2 and undergoes a cycloaddition reaction to prepare cyclic carbonate.

[0058] The present invention also provides a method for catalytically synthesizing cyclic carbonates from CO2, the method comprising the following steps:

[0059] a) Mix the epoxy compound, the co-catalyst, and an organic solvent, which may or may not be added, to obtain a reaction solution;

[0060] b) At room temperature, place the metal ion-doped aminated graphene oxide film material at the bottom of the pressurizing device, add the reaction solution from step a) into the pressurizing device and place it above the metal ion-doped aminated graphene oxide film material, introduce CO2 to replace the air in the pressurizing device, and then continue to introduce CO2 to increase the pressure in the pressurizing device. The reaction solution passes through the metal ion-doped aminated graphene oxide film material under the pressure of CO2 and undergoes a cycloaddition reaction to prepare cyclic carbonate.

[0061] According to an embodiment of the present invention, in step a), the epoxy compound is selected from at least one of propylene oxide, epichlorohydrin, 1,2-epoxybutane, 3,4-epoxy-1,2-butene, allyl glycidyl ether, and styrene oxide.

[0062] According to an embodiment of the present invention, in step a), the organic solvent is selected from at least one of acetonitrile, acetone and dimethyl sulfoxide.

[0063] According to an embodiment of the present invention, in step a), the co-catalyst is selected from at least one of tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, and tetrabutylammonium iodide.

[0064] According to an embodiment of the present invention, in step a), the concentration of the epoxide compound in the reaction solution is 0.2 mol / L to 5 mol / L, for example, 0.2 mol / L, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.5 mol / L, 3.8 mol / L, 4 mol / L, 4.2 mol / L, 4.5 mol / L, 4.8 mol / L, or 5 mol / L.

[0065] According to an embodiment of the present invention, in step a), the molar ratio of the co-catalyst and the epoxide is 1-5:100, for example, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100 or 5:100.

[0066] According to an embodiment of the present invention, in step b), the cycloaddition reaction is carried out at room temperature; the cycloaddition reaction does not require heating during the process.

[0067] According to an embodiment of the present invention, in step b), the pressure required for the cycloaddition reaction is >0.1 MPa and ≤1 MPa, preferably 0.15 MPa-0.9 MPa, or 0.2 MPa-0.8 MPa, or 0.3 MPa-0.7 MPa, or 0.4 MPa-0.6 MPa, or 0.5 MPa. The pressure provided by CO2 during the cycloaddition reaction is >0.1 MPa and ≤1 MPa, preferably 0.15 MPa-0.9 MPa, or 0.2 MPa-0.8 MPa, or 0.3 MPa-0.7 MPa, or 0.4 MPa-0.6 MPa, or 0.5 MPa.

[0068] According to an embodiment of the present invention, in step b), the time required for the cycloaddition reaction is ≤5 min.

[0069] According to an embodiment of the present invention, in step b), after the cycloaddition reaction is completed, the conversion rate of the epoxide compound is 70-100%.

[0070] According to an embodiment of the present invention, in step b), the pressure within the pressurizing device is >0.1 MPa and ≤1 MPa, preferably 0.15 MPa-0.9 MPa, or 0.2 MPa-0.8 MPa, or 0.3 MPa-0.7 MPa, or 0.4 MPa-0.6 MPa, or 0.5 MPa. The pressure within the pressurizing device is provided by introduced CO2. The purity of the CO2 is 99.995%.

[0071] According to an embodiment of the present invention, in step b), the cycloaddition reaction is carried out under stirring conditions. The stirring speed is 200-500 r / min, such as 250 r / min.

[0072] According to an embodiment of the present invention, in step b), a stir bar is provided at the bottom of the pressurizing device to enable the cycloaddition reaction to proceed under stirring conditions; the stir bar does not contact the membrane, thus avoiding damage to the membrane during stirring.

[0073] The beneficial effects of this invention are:

[0074] (1) The nanosheets of the metal ion-doped aminated graphene oxide film material of the present invention provide a two-dimensional confined channel for the reaction, which can reduce the activation energy of epoxy compounds and CO2, so that the cycloaddition reaction of epoxy compounds and CO2 can be carried out at room temperature without heating; at the same time, it also reduces the CO2 pressure required for the cycloaddition reaction, and the cycloaddition reaction can be achieved under the conditions of greater than 0.1 MPa and less than or equal to 1 MPa (preferably greater than 0.1 MPa and less than or equal to 0.5 MPa).

[0075] (2) The metal ion-doped aminated graphene oxide film material of the present invention can simultaneously provide the basic active sites (small organic amine molecules) and acidic active sites (metal ions coordinated with small organic amine molecules) required for the reaction. The synergistic effect of the basic active sites and acidic active sites can significantly improve the activity of the cycloaddition reaction of epoxy compounds and CO2, so that the reaction time is greatly shortened to within 5 minutes. At the same time, by controlling the amount of metal ions added, the number of acidic active sites in the interlayer of the metal ion-doped aminated graphene oxide film can also be controlled, so that the reaction conversion rate can reach 100%. Attached Figure Description

[0076] Figure 1 The present invention describes a preferred embodiment of the process for preparing a cobalt-doped aminated graphene oxide dispersion.

[0077] Figure 2 This is a schematic diagram illustrating the preparation of cobalt-doped aminated graphene oxide membrane material using a vacuum filtration method, according to a preferred embodiment of the present invention, using a cobalt-doped aminated graphene oxide dispersion as raw material.

[0078] Figure 3 This is a physical diagram of an apparatus for catalyzing the cycloaddition reaction of CO2 / epoxide compounds using a cobalt-doped aminated graphene oxide membrane under pressure confined flow, according to a preferred embodiment of the present invention.

[0079] Figure 4 This is a schematic diagram of an apparatus for catalyzing the cycloaddition reaction of CO2 / epoxide compounds using a cobalt-doped aminated graphene oxide membrane under pressure confined flow, according to a preferred embodiment of the present invention. Detailed Implementation

[0080] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0081] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0082] Example 1

[0083] (1) Preparation of 0.67 mg / mL aminated GO dispersion: Take 20 mL of 2 mg / mL GO aqueous dispersion and place it in a 50 mL Erlenmeyer flask. Add 600 μL of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and stir for 1 h. Then add 1 mL of tetraethylenepentamine (TEPA) and stir for 12 h. After dialysis to remove small molecules, dilute with water to 60 mL and sonicate at 150 W for 10 min to obtain 0.67 mg / mL aminated GO dispersion. Store the obtained dispersion in a sealed container at 2 °C. Label the dispersion as GO-TEPA.

[0084] (2) Membrane preparation: Add 0.7 mL of 20 mmol / L CoCl2 aqueous solution to 4.5 mL of the above GO-TEPA dispersion, and add water to a final volume of 40 mL. Sonicate at 150 W for 5 min, and stir for 6 h. Prepare a cobalt-doped aminated GO membrane on a nylon substrate by vacuum filtration. After the water is removed, dry the membrane in a constant temperature and humidity environment of 25 °C and 20% RH for 12 h.

[0085] In the prepared cobalt-doped aminated GO film, the mass percentage of metal ions was 2.2%, and the mass percentage of organic amines was 42.4%. The interlayer spacing of the cobalt-doped aminated GO film was 1.67 nm, and the thickness of the cobalt-doped aminated GO film was 3.3 μm.

[0086] (3) Preparation of reaction solution and reaction: Measure a fixed amount of epichlorohydrin, add a fixed amount (2.5 mol%) of tetrabutylammonium bromide (TBAB) and acetone to prepare a reaction solution with an epichlorohydrin concentration of 1 mol / L, and shake thoroughly. Cut the smooth and flat part of the membrane into a 20 mm diameter disc, fix it at the bottom of the pressurizing device, and place a stir bar that does not contact the membrane. Add 15 mL of reaction solution to the pressurizing device. After assembly, purge the air in the pressurizing device with CO2 for 3 min, and continue to purge with CO2 to increase the pressure in the pressurizing device to 5 atmospheres. Turn on the stirrer and set the speed to 250 r / min. The reaction solution passes through the membrane under the pressure of CO2 and reacts. Collect the liquid that has passed through the membrane and analyze it using nuclear magnetic resonance. 1 H spectrum ( 1 The conversion rate of epichlorohydrin was analyzed by 1H NMR (Bruker, 400MHz).

[0087] Test results show that at a reaction temperature of 25℃±2℃, the residence time of epichlorohydrin molecules in the membrane is about 3 minutes, and the conversion rate of epichlorohydrin is 100%.

[0088] Comparative Example 1

[0089] (1) Preparation of 0.67 mg / mL aminated GO dispersion: Take 20 mL of 2 mg / mL GO aqueous dispersion and place it in a 50 mL Erlenmeyer flask. Add 600 μL of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and stir for 1 h. Then add 1 mL of tetraethylenepentamine (TEPA) and stir for 12 h. After dialysis to remove small molecules, dilute with water to 60 mL and sonicate at 150 W for 10 min to obtain 0.67 mg / mL aminated GO dispersion. Store the obtained dispersion in a sealed container at 2 °C. Label the dispersion as GO-TEPA.

[0090] (2) Membrane preparation: Add water to 4.5 mL of the above GO-TEPA dispersion to a final volume of 40 mL. Sonicate at 150 W for 5 min and stir for 6 h. Prepare an aminated GO membrane on a nylon substrate by vacuum filtration. After the water is removed, dry the membrane in a constant temperature and humidity environment of 25 °C and 20% RH for 12 h.

[0091] The prepared aminated GO membrane contained 43.4% organic amine by mass. The interlayer spacing of the aminated GO membrane was 1.67 nm, and the thickness of the aminated GO membrane was 3.3 μm.

[0092] (3) Preparation of reaction solution and reaction: Measure a fixed amount of epichlorohydrin, add a fixed amount (2.5 mol%) of tetrabutylammonium bromide (TBAB) and acetone to prepare a reaction solution with an epichlorohydrin concentration of 1 mol / L, and shake thoroughly. Cut the smooth and flat part of the membrane into a 20 mm diameter disc, fix it at the bottom of the pressurizing device, and place a stir bar that does not contact the membrane. Add 15 mL of reaction solution to the pressurizing device. After assembly, purge the air in the pressurizing device with CO2 for 3 min, and continue to purge with CO2 to increase the pressure in the pressurizing device to 5 atmospheres. Turn on the stirrer and set the speed to 250 r / min. The reaction solution passes through the membrane under the pressure of CO2 and reacts. Collect the liquid that has passed through the membrane and analyze it using nuclear magnetic resonance. 1 H spectrum ( 1 The conversion rate of epichlorohydrin was analyzed by 1H NMR (Bruker, 400MHz).

[0093] Test results show that at a reaction temperature of 25℃±2℃, the epichlorohydrin molecules reside in the membrane for approximately 3 minutes, and the conversion rate of epichlorohydrin is 45%.

[0094] Comparative Example 2

[0095] (1) Membrane preparation: 0.7 mL of 20 mmol / L CoCl2 aqueous solution was added to 4.5 mL of 0.67 mg / mL GO aqueous dispersion, and water was added to a final volume of 40 mL. The mixture was sonicated at 150 W for 5 min and stirred for 6 h. A cobalt-doped GO membrane was prepared on a nylon substrate by vacuum filtration. After the water was removed, the membrane was dried in a constant temperature and humidity environment of 25 °C and 20% RH for 12 h.

[0096] The mass percentage of metal ions in the prepared cobalt-doped GO film was 2.5%. The interlayer spacing of the cobalt-doped GO film was 0.97 nm, and the thickness of the cobalt-doped GO film was 1.0 μm.

[0097] (2) Preparation of reaction solution and reaction: Measure a fixed amount of epichlorohydrin, add a fixed amount (2.5 mol%) of tetrabutylammonium bromide (TBAB) and acetone to prepare a reaction solution with an epichlorohydrin concentration of 1 mol / L, and shake thoroughly. Cut the smooth and flat part of the membrane into a 20 mm diameter disc, fix it at the bottom of the pressurizing device, and place a stir bar that does not contact the membrane. Add 15 mL of reaction solution to the pressurizing device. After assembly, purge the air from the pressurizing device with CO2 for 3 min, and continue to purge with CO2 to increase the pressure in the pressurizing device to 5 atmospheres. Turn on the stirrer and set the speed to 250 r / min. The reaction solution passes through the membrane under the pressure of CO2 and reacts. Collect the liquid that has passed through the membrane and analyze it using nuclear magnetic resonance. 1 H spectrum ( 1 The conversion rate of epichlorohydrin was analyzed by 1H NMR (Bruker, 400MHz).

[0098] Test results show that at a reaction temperature of 25℃±2℃, the epichlorohydrin molecules reside in the membrane for approximately 1 minute, and the conversion rate of epichlorohydrin is 44.1%.

[0099] Comparative Example 3

[0100] (1) Preparation of cobalt-doped aminated GO powder: Add 0.7 mL of 20 mmol / L CoCl2 aqueous solution to 4.5 mL of GO-TEPA dispersion, sonicate at 150 W for 5 min, stir for 6 h; freeze dry to obtain cobalt-doped aminated GO powder.

[0101] In the prepared cobalt-doped aminated GO powder, the mass percentage of metal ions was 2.2%, and the mass percentage of organic amines was 42.4%.

[0102] (2) Preparation of reaction solution and reaction: A measured amount of epichlorohydrin was added, along with a measured amount (2.5 mol%) of tetrabutylammonium bromide (TBAB) and acetone, to prepare a reaction solution with an epichlorohydrin concentration of 1 mol / L. The solution was thoroughly shaken and set aside. 15 mL of the reaction solution and the cobalt-doped aminated GO powder prepared in step (1) were added, and the mixture was ultrasonically treated at 150 W for 5 min. The mixture was then placed in an autoclave, and CO2 was introduced to purge the air from the autoclave for 3 min. CO2 was then introduced to increase the pressure in the pressurizing device to 5 atmospheres. The stirring was started, and the stirring speed was set to 250 r / min. The reaction was carried out for 72 h. Nuclear magnetic resonance was used to analyze the reaction. 1 H spectrum ( 1 The conversion efficiency was analyzed by 1H NMR (Bruker, 400MHz).

[0103] Test results showed that at a reaction temperature of 25℃±2℃ and a reaction time of 72h, the conversion rate of epichlorohydrin was 24.9%.

[0104] Example 2

[0105] The other operations are the same as in Example 1, except that the epoxy compound is propylene oxide.

[0106] Test results show that at a reaction temperature of 25℃±2℃, the residence time of 1,2-epoxybutane molecules in the membrane is about 3 minutes, and the conversion rate of 1,2-epoxybutane is 100%.

[0107] Comparative Example 4

[0108] The other operations are the same as in Comparative Example 3, except that the epoxy compound is propylene oxide.

[0109] Test results showed that at a reaction temperature of 25℃±2℃ and a reaction time of 72h, the conversion rate of propylene oxide was 11.7%.

[0110] Example 3

[0111] The other operations are the same as in Example 1, except that the epoxide compound is 1,2-epoxybutane.

[0112] Test results show that at a reaction temperature of 25℃±2℃, the residence time of 1,2-epoxybutane molecules in the membrane is about 3 minutes, and the conversion rate of 1,2-epoxybutane is 100%.

[0113] Comparative Example 5

[0114] The other operations are the same as in Comparative Example 3, except that the epoxide compound is 1,2-epoxybutane.

[0115] Test results showed that at a reaction temperature of 25℃±2℃ and a reaction time of 72h, the conversion rate of 1,2-epoxybutane was 9.2%.

[0116] Example 4

[0117] The other operations are the same as in Example 1, except that the epoxy compound is 3,4-epoxy-1,2-butene.

[0118] Test results showed that at a reaction temperature of 25℃±2℃, the residence time of 3,4-epoxy-1,2-butene molecules in the membrane was approximately 3 minutes, and the conversion rate of 3,4-epoxy-1,2-butene was 100%.

[0119] Comparative Example 6

[0120] The other operations are the same as in Comparative Example 3, except that the epoxy compound is 3,4-epoxy-1,2-butene.

[0121] Test results showed that at a reaction temperature of 25℃±2℃ and a reaction time of 72h, the conversion rate of 3,4-epoxy-1,2-butene was 5.7%.

[0122] Example 5

[0123] The other operations are the same as in Example 1, except that the epoxy compound is allyl glycidyl ether.

[0124] Test results show that at a reaction temperature of 25℃±2℃, the residence time of allyl glycidyl ether molecules in the membrane is about 3 minutes, and the conversion rate of allyl glycidyl ether is 100%.

[0125] Comparative Example 7

[0126] The other operations are the same as in Comparative Example 3, except that the epoxy compound is allyl glycidyl ether.

[0127] Test results showed that at a reaction temperature of 25℃±2℃ and a reaction time of 72h, the conversion rate of allyl glycidyl ether was 4.5%.

[0128] Example 6

[0129] The other operations are the same as in Example 1, except that 0.6 mL of 20 mmol / L CoCl2 aqueous solution is added in step (2).

[0130] In the prepared cobalt-doped aminated GO film, the mass percentage of metal ions was 1.9%, and the mass percentage of organic amines was 42.5%. The interlayer spacing of the cobalt-doped aminated GO film was 1.67 nm, and the thickness of the cobalt-doped aminated GO film was 3.3 μm.

[0131] Test results show that at a reaction temperature of 25℃±2℃, the epichlorohydrin molecules reside in the membrane for approximately 3 minutes, and the conversion rate of epichlorohydrin is 78.7%.

[0132] Example 7

[0133] The other operations are the same as in Example 1, except that 1 mL of tris(2-aminoethyl)amine is added in step (1).

[0134] Test results showed that at a reaction temperature of 25℃±2℃, the epichlorohydrin molecules remained in the membrane for about 3 minutes, and the conversion rate of epichlorohydrin was 80.4%.

[0135] Example 8

[0136] The other operations are the same as in Example 1, except that in step (2), 0.467 mL of 20 mmol / L CoCl2 aqueous solution is added to 3 mL of GO-TEPA dispersion. 0.7 mL of 20 mmol / L CoCl2 aqueous solution is added to 4.5 mL of the above GO-TEPA dispersion.

[0137] In the prepared cobalt-doped aminated GO film, the mass percentage of metal ions was 2.2%, and the mass percentage of organic amines was 42.4%. The interlayer spacing of the cobalt-doped aminated GO film was 1.67 nm, and the thickness of the cobalt-doped aminated GO film was 2.2 μm.

[0138] Test results show that at a reaction temperature of 25℃±2℃, the epichlorohydrin molecules reside in the membrane for approximately 1 minute, and the conversion rate of epichlorohydrin is 84.0%.

[0139] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The use of a metal ion-doped aminated graphene oxide film material in the rapid catalytic cycloaddition reaction of CO2 / epoxide compounds to synthesize cyclic carbonates at room temperature; wherein room temperature refers to a temperature range of 20-30°C; and rapid refers to a reaction time of 30-300 s. The metal ion-doped aminated graphene oxide film material comprises graphene oxide, organic amines, and metal ions; the organic amines are chemically modified on the surface and interlayer of the graphene oxide; the metal ions are doped into the surface and interlayer of the graphene oxide. The metal ions are selected from Fe. 3+ Co 2+ and Ni 2+ At least one of them; The organic amine is selected from at least one of triethylenetetramine, tetraethylenepentamine, tri(2-aminoethyl)amine, 4-aminomethylpyridine, and 1,5-diaminomethylpyridine.

2. The use according to claim 1, wherein, The metal ions in the metal ion-doped aminated graphene oxide film material account for 0.01-5 wt% of the total mass of the film material; and / or, the organic amines in the metal ion-doped aminated graphene oxide film material account for 5-50 wt% of the total mass of the film material.

3. The use according to claim 1, wherein, The thickness of the metal ion-doped aminated graphene oxide film material is 0.1-5 μm.

4. The use according to claim 1, wherein, The interlayer spacing of the metal ion-doped aminated graphene oxide film material is 1-2 nm.

5. The use according to any one of claims 1-4, wherein, The metal ion-doped aminated graphene oxide film material was prepared by the following method: (1) The graphene oxide dispersion, organic amine and activator were mixed and reacted, followed by dialysis and ultrasonic treatment to prepare an aminated graphene oxide dispersion. (2) Add metal salt to the aminated graphene oxide dispersion and mix ultrasonically to obtain a metal ion-doped aminated graphene oxide dispersion. (3) Using vacuum filtration, the metal ion-doped aminated graphene oxide dispersion from step (2) is assembled into a metal ion-doped aminated graphene oxide membrane, and then subjected to constant temperature and humidity static treatment to prepare the metal ion-doped aminated graphene oxide membrane material.

6. The use according to claim 5, wherein, In step (1), the activator is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide; And / or, in step (1), the concentration of the graphene oxide dispersion is 0.5-2 mg / mL; And / or, in step (1), the mass ratio of the graphene oxide to the organic amine is 1:12-1:50; And / or, in step (1), the mass ratio of the graphene oxide to the activator is 1:8-1:25; And / or, in step (1), the concentration of the aminated graphene oxide dispersion is 0.5-1.5 mg / mL; And / or, in step (3), the constant temperature and humidity static treatment is carried out in a constant temperature and humidity chamber, and the constant temperature and humidity static treatment is carried out at 20-30℃ and 10-20%RH for 12-24h.

7. The use according to claim 5, wherein, In step (2), the molar mass ratio of the metal salt and the aminated graphene oxide is 2-30µmol / 2.25-6.75mg.

8. The use according to claim 5, wherein, In step (2), the molar volume ratio of the metal salt and the aminated graphene oxide dispersion is 2-30 µmol / 4.5 mL.

9. The use according to any one of claims 1-4, wherein, The method for catalytically synthesizing cyclic carbonates from CO2 includes the following steps: a) Mix the epoxy compound, the co-catalyst, and an organic solvent, optionally added or not added, to obtain a reaction solution; b) At room temperature, place the metal ion-doped aminated graphene oxide film material at the bottom of the pressurizing device, add the reaction solution from step a) into the pressurizing device and place it above the metal ion-doped aminated graphene oxide film material, introduce CO2 to replace the air in the pressurizing device, and then continue to introduce CO2 to increase the pressure in the pressurizing device. The reaction solution passes through the metal ion-doped aminated graphene oxide film material under the pressure of CO2 and undergoes a cycloaddition reaction to prepare cyclic carbonate.

10. A method for catalytically synthesizing cyclic carbonates from CO2, the method comprising the following steps: a) Mix the epoxy compound, the co-catalyst, and an organic solvent, optionally added or not added, to obtain a reaction solution; b) At room temperature, a metal ion-doped aminated graphene oxide film is placed at the bottom of a pressurizing device. The reaction solution from step a) is added to the pressurizing device and placed above the metal ion-doped aminated graphene oxide film. CO2 is introduced to replace the air in the pressurizing device, and then CO2 is continued to be introduced to increase the pressure in the pressurizing device. The reaction solution passes through the metal ion-doped aminated graphene oxide film under the pressure of CO2 and undergoes a cycloaddition reaction to prepare cyclic carbonate. The room temperature refers to a temperature range of 20-30°C. The metal ion-doped aminated graphene oxide film material comprises graphene oxide, organic amines, and metal ions; the organic amines are chemically modified on the surface and interlayer of the graphene oxide; the metal ions are doped into the surface and interlayer of the graphene oxide. The metal ions are selected from Fe. 3+ Co 2+ and Ni 2+ At least one of them; The organic amine is selected from at least one of triethylenetetramine, tetraethylenepentamine, tri(2-aminoethyl)amine, 4-aminomethylpyridine, and 1,5-diaminomethylpyridine.

11. The method according to claim 10, wherein, In step a), the epoxy compound is selected from at least one of propylene oxide, epichlorohydrin, 1,2-epoxybutane, 3,4-epoxy-1,2-butene, allyl glycidyl ether, and styrene oxide. And / or, in step a), the organic solvent is selected from at least one of acetonitrile, acetone and dimethyl sulfoxide; And / or, in step a), the co-catalyst is selected from at least one of tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, and tetrabutylammonium iodide; And / or, in step a), the concentration of the epoxide in the reaction solution is 0.2 mol / L-5 mol / L; And / or, in step a), the molar ratio of the co-catalyst to the epoxide is 1-5:

100.

12. The method according to claim 10, wherein, In step b), the cycloaddition reaction is carried out at room temperature; And / or, in step b), the time required for the cycloaddition reaction is ≤5 min; And / or, in step b), the pressure inside the pressurizing device is >0.1MPa and ≤1MPa.

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