Two-dimensional fullerene film for h2 purification and preparation method and application thereof

Abstract

The application discloses a two-dimensional fullerene film for H2 purification and a preparation method and application thereof. After magnesium powder and fullerene are mixed and high-temperature treated, the two-dimensional fullerene nanosheet dispersion liquid is obtained through centrifugation after peeling off with a peeling agent, and ultrasonic treatment after being dispersed and centrifugated with distilled water, ethanol and N-methyl-2-pyrrolidone respectively. Finally, the two-dimensional fullerene film loaded on a substrate is obtained by depositing on the substrate. The two-dimensional fullerene film prepared by the method has high H2 permeability and excellent selectivity for various gas mixtures.

Description

Technical Field

[0001] This invention belongs to the field of gas separation membrane technology, specifically relating to a method for preparing a two-dimensional fullerene membrane for H2 purification and its application in gas separation. Background Technology

[0002] With the increasing proportion of hydrogen energy in the energy structure, the separation and purification of hydrogen has attracted widespread attention. Membrane separation, due to its advantages such as low energy consumption, simple operation, and controllable scale, has become one of the current research hotspots at the forefront of science and technology. Currently, hydrogen separation membranes are mainly divided into organic separation membranes and inorganic separation membranes. However, organic separation membranes have disadvantages such as poor heat resistance and poor chemical stability. Although inorganic membranes possess good chemical stability and mechanical strength, their preparation cost is high, and they are difficult to prepare and apply on a large scale. Therefore, the preparation of novel membrane separation materials is of great significance in addressing the above problems.

[0003] In recent years, two-dimensional materials have attracted significant attention from researchers due to their unique chemical and physical properties resulting from their atomic-level thickness and size. Two-dimensional nanosheets with high-density intraplane pores are ideal materials for constructing advanced molecular sieving membranes. However, the preparation of separation membranes with high selectivity and high throughput still faces significant challenges. Although electron and ion radiation, oxygen plasma etching, and other methods can generate nanoscale pores, these typically require complex equipment and suffer from problems such as large pore size variability and insufficient membrane selectivity. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a two-dimensional fullerene film for H2 purification, its preparation method, and its application in gas separation, specifically for the separation of H2 and gas molecules with different kinetic diameters and characteristics.

[0005] A first aspect of the present invention provides a method for preparing a two-dimensional fullerene thin film, comprising the following steps:

[0006] 1) After mixing magnesium powder and fullerene evenly, the mixture is treated at high temperature for 15-30 hours to obtain polyfullerene powder, wherein the high temperature is 520-550℃.

[0007] 2) The polyfullerene powder obtained in step 1) is dispersed in an organic solvent containing a stripping agent and stirred to obtain a stripped dispersion; wherein,

[0008] The stripping agent is selected from: tetrabutylsalicylic acid amine (TBAS) and salicylic acid;

[0009] The organic solvent is selected from: N-methyl-2-pyrrolidone, dimethylformamide, acetone, and methanol;

[0010] 3) Centrifuge the dispersion obtained in step 2) at 500-3000 rpm for 5-20 min and take the upper dispersion.

[0011] 4) Centrifuge the upper dispersion obtained in step 3) at 10,000-20,000 rpm for 20-40 min and collect the precipitate;

[0012] 5) Disperse the precipitate obtained in step 4) with distilled water and centrifuge at 10,000-20,000 rpm for 20-40 min, then collect the precipitate;

[0013] 6) Disperse the precipitate obtained in step 5) with ethanol, methanol, or isopropanol and centrifuge at 10,000-20,000 rpm for 20-40 min, then collect the precipitate.

[0014] 7) Disperse the precipitate from step 6) with an organic solvent, and centrifuge at 10,000-20,000 rpm for 20-40 minutes, then collect the precipitate; wherein,

[0015] The organic solvent is selected from: N-methyl-2-pyrrolidone, dimethylformamide, acetone, and methanol;

[0016] 8) Disperse the precipitate from step 7) with an organic solvent and sonicate it. Centrifuge at 3000-6000 rpm for 20-40 min, and collect the upper dispersion, which is a two-dimensional fullerene nanosheet dispersion; wherein,

[0017] The organic solvent is selected from: N-methyl-2-pyrrolidone, dimethylformamide, acetone, and methanol;

[0018] 9) Two-dimensional fullerene nanosheets were deposited onto the substrate using two-dimensional nanosheet film deposition technology to obtain a two-dimensional fullerene film loaded on the substrate.

[0019] In another preferred embodiment, in step 1), a high-temperature treatment is performed under an inert atmosphere, wherein the inert atmosphere is selected from argon atmosphere or helium atmosphere.

[0020] In another preferred embodiment, in step 1), the inert gas is an argon atmosphere or a helium atmosphere to protect the fullerene from oxidation.

[0021] In another preferred embodiment, in step 1), magnesium powder and fullerene are mixed evenly, placed in a quartz tube, sealed, and placed in a tube furnace for high-temperature treatment in an inert atmosphere, and then cooled to room temperature to obtain polyfullerene powder.

[0022] In another preferred embodiment, the high temperature is 530-550°C, more preferably 535-545°C, and even more preferably 540°C.

[0023] In another preferred embodiment, in step 1), the high-temperature treatment is performed by holding at 530-550°C for 20 hours and then cooling to room temperature, with a heating rate of 1-2°C / min.

[0024] In another preferred embodiment, in step 1), the inert atmosphere is an argon atmosphere; the high-temperature treatment is to heat to 535-545℃, hold for 20 hours, and then cool to room temperature, with a heating rate of 1-3℃ / min.

[0025] In another preferred embodiment, in step 1), the heating rate is 2°C / min.

[0026] In this invention, room temperature refers to 20-30℃.

[0027] In another preferred embodiment, the polyfullerene powder is a tetragonal crystal.

[0028] In another preferred embodiment, in step 2), the stirring treatment lasts for 4-10 days.

[0029] In another preferred embodiment, in step 2), the stirring is done with a magnetic stirrer, and the stirring time is 7 days.

[0030] In another preferred embodiment, in step 2), the organic solvent refers to an organic solvent that can stably disperse the two-dimensional fullerene nanosheets, namely N-methylpyrrolidone; the stripping agent is tetrabutylsalicylic acid amine; the stirring is done using a magnetic stirrer, and the stirring time is 4-7 days.

[0031] In another preferred embodiment, in step 3), the dispersion obtained in step 2) is centrifuged at 800-1500 rpm for 8-15 min. In another preferred embodiment, it is centrifuged at 1000 rpm for 10 min.

[0032] In another preferred embodiment, in step 4), the upper dispersion obtained in step 3) is centrifuged at 10,000-15,000 rpm for 25-35 min. In another preferred embodiment, it is centrifuged at 12,000 rpm for 30 min.

[0033] In another preferred embodiment, in step 5), the precipitate obtained in step 4) is dispersed with distilled water and centrifuged at 10,000-15,000 rpm for 25-35 min. In another preferred embodiment, it is centrifuged at 12,000 rpm for 30 min.

[0034] In another preferred embodiment, step 5) is repeated 2-3 times.

[0035] In another preferred embodiment, in step 6), the precipitate obtained in step 5) is dispersed in ethanol and centrifuged at 10,000-15,000 rpm for 25-35 min. In another preferred embodiment, it is centrifuged at 12,000 rpm for 30 min.

[0036] In another preferred embodiment, step 6) is repeated 2-3 times.

[0037] In another preferred embodiment, in step 7), the precipitate from step 6) is dispersed in an organic solvent and centrifuged at 10,000-15,000 rpm for 25-35 min. In another preferred embodiment, it is centrifuged at 12,000 rpm for 30 min.

[0038] In another preferred embodiment, in step 8), the ultrasonic treatment time is 3-5 minutes.

[0039] In another preferred embodiment, in step 8), the sample is centrifuged at 3500-5000 rpm for 25-35 min. In another preferred embodiment, the sample is centrifuged at 4000 rpm for 30 min.

[0040] In another preferred embodiment, step 8) is repeated 3-5 times.

[0041] In another preferred embodiment, step 8) is repeated 3 or 4 times.

[0042] In another preferred embodiment, the thickness of the two-dimensional fullerene nanosheets obtained in step 8) is approximately 1.6–1.8 nm.

[0043] In another preferred embodiment, in step 9), a two-dimensional fullerene nanosheet dispersion is deposited onto a substrate, and a two-dimensional fullerene nanosheet is deposited onto the substrate by vacuum filtration to obtain a thin film. The deposited thin film is then washed with ethanol, and after the ethanol evaporates, a two-dimensional fullerene thin film loaded on the substrate is obtained.

[0044] In another preferred embodiment, the substrate is an alumina sheet. In yet another preferred embodiment, the substrate is a porous alumina sheet.

[0045] In another preferred embodiment, the porous alumina sheet has a pore size of 50-250 nm.

[0046] In another preferred embodiment, the porous alumina sheet has a pore size of 100-200 nm.

[0047] In a second aspect, the present invention provides a two-dimensional fullerene film prepared by the preparation method described in the first aspect.

[0048] In another preferred embodiment, the thickness of the two-dimensional fullerene film is 5-200 nm.

[0049] In another preferred embodiment, the thickness of the two-dimensional fullerene film is 10-100 nm.

[0050] In another preferred embodiment, the thickness of the two-dimensional fullerene film is 10-80 nm.

[0051] In another preferred embodiment, the thickness of the two-dimensional fullerene film is 20-150 nm.

[0052] In another preferred embodiment, the thickness of the two-dimensional fullerene film is 50-80 nm.

[0053] In another preferred embodiment, the two-dimensional fullerene film exhibits an H2 permeability of 4898 GPU or even higher.

[0054] In another preferred embodiment, the pore size of the two-dimensional fullerene film is: Pore ​​density: 1×10 12 -5×10 14 cm -2 .

[0055] In another preferred embodiment, the pore size of the two-dimensional fullerene film is: Pore ​​density: 1.35 × 10 14 cm 2 .

[0056] In another preferred embodiment, the average interlayer spacing of the two-dimensional fullerene film is 0.6-1 nm, more preferably 0.7-0.9 nm, and even more preferably 0.88 nm.

[0057] A third aspect of the invention provides the use of the two-dimensional fullerene film described in the second aspect for purifying H2.

[0058] In another preferred embodiment, the purification of H2 involves separating H2 from gas molecules with different kinetic diameters and characteristics, wherein the gas molecules with different kinetic diameters and characteristics are carbon dioxide, methane, propylene, propane, or a mixture of two or more gases.

[0059] A fourth aspect of the present invention provides a method for purifying H2, comprising the following steps: placing the two-dimensional fullerene membrane described in the second aspect in a gas membrane separation device, and introducing a mixed gas to separate and purify H2, wherein...

[0060] The mixed gas contains:

[0061] H2;

[0062] A mixture of one or more gases selected from carbon dioxide, methane, propylene, and propane.

[0063] The polyfullerene of this invention has a similar stacked structure to many two-dimensional material exfoliation precursors currently discovered. The organic cation intercalation exfoliation method allows organic cations to enter the interlayer, enabling the polyfullerene to be exfoliated into nanosheets during stirring. Furthermore, the two-dimensional fullerene nanosheets themselves have inherently high-density funnel-shaped nanopores and suitable pore size, thus they can be used for the separation of H2 from gas molecules with different kinetic diameters and characteristics.

[0064] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0065] 1) The two-dimensional fullerene nanosheets in this invention have high air permeability and good performance in separating mixed gases, and have excellent application prospects.

[0066] 2) The funnel-shaped nanopores inherent in the two-dimensional fullerene nanosheets of this invention can achieve efficient H2 transport, and the appropriate pore size can achieve effective separation of H2 from molecules with different kinetic diameters and characteristics.

[0067] 3) The two-dimensional fullerene film of the present invention achieves a separation ratio of more than 60.3 for hydrogen and gas molecules with different kinetic diameters and characteristics, and the H2 flux reaches 4898 GPU at 50-150 kPa and 30-70 °C.

[0068] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0069] Figure 1 This is a scanning electron microscope image of the polyfullerene powder in Example 1.

[0070] Figure 2 This is the theoretical structural diagram of the fullerene nanosheets in Example 1.

[0071] Figure 3 This is an atomic force microscope image of the two-dimensional fullerene nanosheets in Example 1.

[0072] Figure 4 This is an electron microscope image of the surface of the two-dimensional fullerene film in Example 1.

[0073] Figure 5 This is an electron microscope image of the cross-section of the two-dimensional fullerene film in Example 1.

[0074] Figure 6 The images show X-ray diffraction patterns of fullerene, polyfullerene powder, and two-dimensional fullerene film from Example 1.

[0075] Figure 7 This is a graph showing the single-component gas flux of the two-dimensional fullerene film in Example 1, as determined by chromatography.

[0076] Figure 8 This is a bar chart showing the gas separation ratio of the two-dimensional fullerene film in Example 1. Detailed Implementation

[0077] The inventors of this application, through extensive and in-depth research, have developed a method for preparing two-dimensional fullerene films for H2 purification. 60 The gas transport path of the thin film consists of high-density in-plane funnel-shaped nanopores (pore size: Pore ​​density: 1×10 12 -5×10 14 / cm 2 The structure, consisting of interlayer pathways, exhibits H2 permeability of 4898 GPU or even higher, and demonstrates excellent selectivity for mixtures of various gases. Based on this, the present invention was completed.

[0078] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are weight percentages and parts by weight.

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0080] Example 1

[0081] Preparation of two-dimensional fullerene thin films

[0082] Magnesium powder and fullerene were mixed evenly and placed in a quartz tube, sealed, and placed in a tube furnace. Under an argon atmosphere, the temperature was increased to 540°C at 2°C / min and held for 20 hours. Then, the temperature was naturally cooled to room temperature to obtain polyfullerene powder.

[0083] The obtained polyfullerene powder was added to 40 mg / mL NMP containing TBAS and stirred for 7 days to obtain the exfoliated dispersion.

[0084] The exfoliated dispersion was centrifuged at 1000 rpm for 10 min, the supernatant was collected and centrifuged at 12000 rpm for 30 min, the precipitate was collected and dispersed in distilled water; the dispersed mixture was centrifuged at 12000 rpm for 30 min (this step needs to be repeated twice), the precipitate was collected and dispersed in ethanol; the dispersed mixture was centrifuged at 12000 rpm for 30 min (this step needs to be repeated twice), the precipitate was collected and dispersed in NMP; the dispersed mixture was centrifuged at 12000 rpm for 30 min, the precipitate was collected and dispersed in NMP and sonicated; the sonicated mixture was centrifuged at 4000 rpm for 30 min, the supernatant was collected (this step needs to be repeated 3 times), and two-dimensional fullerene nanosheets dispersed in NMP were obtained. The concentration was determined to be 0.02 mg / mL by UV spectrophotometer calibration.

[0085] Using porous alumina sheets with a pore size range of 50-250 nm as a substrate, a vacuum-assisted filtration film deposition technique was employed. Specifically, a two-dimensional nanosheet film deposition technique was used to deposit two-dimensional fullerene nanosheets onto the substrate. Vacuum filtration utilized a sand core filter connected to a circulating water vacuum pump, with a vacuum level ranging from 0 to -100 kPa and a running time of 3 to 12 hours. The deposited film was washed with ethanol and allowed to air dry naturally to allow residual ethanol to evaporate, yielding a two-dimensional fullerene film supported on porous alumina, ready for use in H2 purification.

[0086] Scanning electron microscopy (SEM) was performed on the polyfullerene powder, and the results are as follows: Figure 1 As shown, by Figure 1 The resulting square crystals (magnesium-fullerene crystals) can be seen.

[0087] The theoretical structural model of two-dimensional fullerene nanosheets is as follows: Figure 2 As shown, theoretical calculations can determine the pore size of its funnel-shaped nanopores as follows: The porosity is 1.35 × 10⁻⁶. 14 / cm 2 This aperture size and pore density provide a large number of in-plane gas transport paths.

[0088] Atomic force microscopy (AFM) was used to test the two-dimensional fullerene nanosheets, and the results are as follows: Figure 3 As shown, by Figure 3 It can be seen that the thickness of the two-dimensional fullerene nanosheets is approximately 1.7 nm.

[0089] SEM tests were performed on the surface and cross-section of the two-dimensional fullerene film, and the results are as follows: Figure 4 and Figure 5 As shown, by Figure 4 and Figure 5 It can be seen that the thickness of the two-dimensional fullerene film prepared in this embodiment is approximately 73.2 nm.

[0090] X-ray diffraction (XRD) tests were performed on fullerenes, polyfullerene powders, and two-dimensional fullerene films, respectively. Figure 6 It can be seen that the (002) and (200) peaks of the polyfullerene powder highly coincide with the main peaks of the XRD spectrum obtained from the theoretical structural simulation. The (002) peak of the exfoliated fullerene nanosheet film shifts to the left, indicating that the interlayer spacing changes due to secondary stacking after successful exfoliation. At the same time, the average interlayer spacing is calculated to be 0.88 nm using the Bragg formula on the XRD data of the two-dimensional fullerene film, which provides interlayer gas transport channels.

[0091] Example 2

[0092] Application of two-dimensional fullerene films in H2 purification

[0093] The two-dimensional fullerene film deposited on porous alumina in Example 1 was sealed in a gas membrane separation device (Journal of Membrane Science, 711, 123163; Chemical Engineering Journal, 498, 155773; Journal of Membrane Science, 679, 121696). The single-component gas fluxes of hydrogen, carbon dioxide, methane, propylene, and propane through the membrane, as well as the gas fluxes of hydrogen / carbon dioxide, hydrogen / methane, hydrogen / propylene, and hydrogen / propane mixtures, were determined by chromatography. The theoretical separation ratio of hydrogen from other gases and the separation ratio of the mixed gases were calculated. Specifically, the test temperatures were 30°C, 40°C, 50°C, 60°C, and 70°C, and the test pressures were 50 kPa, 75 kPa, 100 kPa, and 150 kPa.

[0094] like Figure 7 As shown, the single-component gas fluxes for hydrogen, carbon dioxide, methane, propylene, and propane are 4898 GPU, 51.5 GPU, 70.7 GPU, 5.5 GPU, and 4.9 GPU, respectively.

[0095] like Figure 8 As shown, the ideal separation ratios of hydrogen / carbon dioxide, hydrogen / methane, hydrogen / propylene, and hydrogen / propane mixtures are 91.8, 66.1, 881.7, and 973.4, respectively; and the separation ratios of hydrogen / carbon dioxide, hydrogen / methane, hydrogen / propylene, and hydrogen / propane mixtures are 88.5, 60.3, 677.7, and 838.8, respectively.

[0096] Example 3

[0097] The two-dimensional fullerene nanosheet dispersion obtained in Example 1 was deposited onto a commercially available double-through anodized aluminum substrate. The commercially available double-through anodized aluminum substrate was from Whatman, model [6809-6002].

[0098] A two-dimensional fullerene membrane prepared on commercially available double-through anodic aluminum oxide was installed into a self-made gas separation test device, and the separation performance of hydrogen and carbon dioxide was tested at 30°C and 100 kPa.

[0099] After testing, the two-dimensional fullerene membrane based on anodic aluminum oxide achieved a hydrogen flux of up to 10600 GPUs.

[0100] Example 4

[0101] Magnesium powder and fullerene were mixed evenly and placed in a quartz tube, sealed, and placed in a tube furnace. Under an argon atmosphere, the temperature was increased to 500°C at 2°C / min and held for 20 hours. Then, the temperature was naturally cooled to room temperature to obtain polyfullerene powder.

[0102] The obtained polyfullerene powder was subjected to XRD testing. The XRD spectrum showed that the crystallization effect under the 500℃ heat preservation condition was poor, and it was not suitable for assembly into a film after peeling.

[0103] Example 5

[0104] Magnesium powder and fullerene were mixed evenly and placed in a quartz tube, sealed, and placed in a tube furnace. Under an argon atmosphere, the temperature was increased to 580°C at 2°C / min and held for 20 hours. Then, the temperature was naturally cooled to room temperature to obtain polyfullerene powder.

[0105] The obtained polyfullerene powder was subjected to XRD test. The XRD spectrum showed that the peak of the (002) crystal plane under the heat preservation condition of 580℃ split. The split part highly coincided with the main peak of the pure fullerene phase, indicating that decomposition occurred.

[0106] The above embodiments are merely preferred embodiments of the present invention and are used only to explain the present invention, not to limit the present invention. Any changes, substitutions, combinations, simplifications, modifications, etc., made by those skilled in the art without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a two-dimensional fullerene thin film, comprising the following steps: 1) After mixing magnesium powder and fullerene evenly, the mixture is treated at high temperature for 15-30 hours to obtain polyfullerene powder, wherein the high temperature is 520-550℃. 2) Disperse the polyfullerene powder obtained in step 1) in an organic solvent containing a stripping agent and stir to obtain a stripped dispersion; wherein, the stripping agent is selected from: tetrabutylsalicylic acid amine, salicylic acid; the organic solvent is selected from: N-methyl-2-pyrrolidone, dimethylformamide, acetone, methanol; 3) Centrifuge the dispersion obtained in step 2) at 500-3000 rpm for 5-20 min and take the upper dispersion. 4) Centrifuge the upper dispersion obtained in step 3) at 10,000-20,000 rpm for 20-40 min and collect the precipitate; 5) Disperse the precipitate obtained in step 4) with distilled water and centrifuge at 10,000-20,000 rpm for 20-40 min, then collect the precipitate; 6) Disperse the precipitate obtained in step 5) with ethanol, methanol or isopropanol and centrifuge at 10,000-20,000 rpm for 20-40 min, then collect the precipitate; 7) Disperse the precipitate from step 6) with an organic solvent and centrifuge at 10,000-20,000 rpm for 20-40 min, then remove the precipitate; the organic solvent is selected from: N-methyl-2-pyrrolidone, dimethylformamide, acetone, and methanol; 8) Disperse the precipitate from step 7) with an organic solvent and sonicate it. Centrifuge at 3000-6000 rpm for 20-40 min and take the upper dispersion, which is a two-dimensional fullerene nanosheet dispersion. The organic solvent is selected from: N-methyl-2-pyrrolidone, dimethylformamide, acetone, and methanol. 9) Two-dimensional fullerene nanosheets were deposited onto the substrate using two-dimensional nanosheet film deposition technology to obtain a two-dimensional fullerene film loaded on the substrate.

2. The preparation method according to claim 1, characterized in that, In step 1), a high-temperature treatment is performed under an inert atmosphere, wherein the inert atmosphere is selected from argon atmosphere or helium atmosphere.

3. The preparation method according to claim 2, characterized in that, In step 1), magnesium powder and fullerene are mixed evenly, placed in a quartz tube, sealed, and placed in a tube furnace. The mixture is then subjected to high-temperature treatment in an inert atmosphere and cooled to room temperature to obtain polyfullerene powder.

4. The preparation method according to claim 1, characterized in that, In step 2), the stirring process lasts for 4-10 days.

5. The preparation method according to claim 1, characterized in that, Step 5) Repeat 2-3 times.

6. The preparation method according to claim 1, characterized in that, Step 6) Repeat 2-3 times.

7. The preparation method according to claim 1, characterized in that, Step 8) Repeat 3-5 times.

8. A two-dimensional fullerene thin film, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The use of the two-dimensional fullerene film as described in claim 8, characterized in that, Used for purifying H2.

10. The use as described in claim 9, characterized in that, The purification of H2 involves separating H2 from gas molecules with different kinetic diameters and characteristics, wherein the gas molecules with different kinetic diameters and characteristics are carbon dioxide, methane, propylene, propane, or a mixture of two or more gases.

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