An electrochemical synthesis method of a ZIF-90 material
ZIF-90 polycrystalline membranes were prepared by electrochemical synthesis, which solved the problem of insufficient propylene permeation in traditional methods, achieved efficient propylene/propane separation, and improved the membrane's separation performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-18
- Publication Date
- 2026-06-16
AI Technical Summary
Existing membrane separation technologies have insufficient propylene permeate flow during propylene/propane separation, making it difficult to meet stringent purity and productivity requirements. Traditional hydrothermal/solvothermal methods for preparing ZIF-90 materials have defects that affect separation efficiency.
ZIF-90 material was synthesized by an electrochemical method. By growing polycrystalline films in situ on the substrate, the use of template agents was avoided. Continuous and defect-free ZIF-90 polycrystalline films were prepared under mild conditions using an electrosynthesis reaction.
It increases propylene permeation and enhances propylene/propane selectivity, achieving more efficient gas separation performance and showing promising application prospects.
Smart Images
Figure CN122214883A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of zeolite imidazole metal-organic framework materials, specifically relating to an electrochemical synthesis method for ZIF-90 material. Background Technology
[0002] Industrial gas separation has traditionally relied on energy-intensive cryogenic distillation processes, contributing significantly to global energy consumption. Membrane technology offers an energy-efficient and attractive alternative by separating molecules based on size differences rather than boiling points. However, the feasibility of this transition faces challenges, particularly in separation processes requiring stringent purity standards, such as the production of polymer-grade propylene (99.5%) from propane. A complete shift from distillation to membrane separation necessitates the development of membranes with excellent propylene / propane selectivity and high propylene permeate throughput to ensure both purity requirements and productivity. While both propylene permeate throughput and propylene / propane selectivity affect the final purification cost of the mixed system, propylene permeate throughput has a more significant impact, especially given the higher cost of membranes. Membranes made from zeolite imidazole framework-8 (ZIF-8) are considered the benchmark for propylene / propane separation, with propylene permeate throughput ranging from 10 to 100 GPUs (GPU: gas permeation unit; 1 GPU = 3.348 × 10⁻⁶). 10 mol m 2 s 1 Pa 1 Within the range of ), propylene / propane selectivity exceeds 100. By replacing the ligand dimethylimidazole of ZIF-8 with the slightly smaller imidazole dicarboxaldehyde, a slightly larger pore size ZIF-90 framework can be generated, thereby significantly improving propylene permeability. Summary of the Invention
[0003] To overcome the problems existing in the prior art, one objective of this invention is to provide an electrochemical synthesis method for ZIF-90 material. A second objective of this invention is to provide the ZIF-90 material obtained by the above-mentioned electrochemical synthesis method. A third objective of this invention is to provide applications of the above-mentioned ZIF-90 material. To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides an electrochemical synthesis method for ZIF-90 material, comprising the following steps: A mixed solution containing imidazole-2-carboxaldehyde and a zinc source was prepared; the mixed solution was placed in an electrolytic cell, and positive and negative electrodes were inserted to carry out an electrosynthesis reaction under dual electrodes to obtain a ZIF-90 material film.
[0004] Preferably, the molar ratio of the zinc source to imidazole-2-carboxaldehyde is 1:(4~50).
[0005] More preferably, the molar ratio of the zinc source to imidazole-2-carboxaldehyde is 1:(4~30). For example, 1:(4~20).
[0006] The synthesis method of the present invention is to directly grow ZIF-90 polycrystalline films in situ on the substrate. Subunit structures need to be generated in the solution before polycrystalline ZIF-90 films can be grown in situ under the action of an electric field. By adding more ligands (relative to the zinc source) to the precursor solution, structure-guided subunits can be generated, thereby guiding the orderly deposition of ligands and metal salts.
[0007] Preferably, the zinc source includes at least one of zinc nitrate and zinc acetate.
[0008] Preferably, the method for preparing the mixed solution includes the following steps: Imidazole-2-carboxaldehyde was dissolved in methanol to prepare solution A; a zinc source was dissolved in methanol to prepare solution B; solutions A and B were mixed to prepare a mixed solution.
[0009] More preferably, the concentration of imidazole-2-carboxaldehyde in solution A is 0.12-1.5 mol·L⁻¹. -1 .
[0010] More preferably, the preparation method of solution A specifically includes: dissolving imidazole-2-carboxaldehyde in methanol solvent, heating to 30-65℃, maintaining for 5-40 min, and cooling to obtain a clear imidazole-2-carboxaldehyde solution.
[0011] Preferably, the positive electrode includes a substrate and a metal layer; the metal layer is disposed on the surface of the substrate; the substrate includes one of polysulfone (PSF), polyimide (PI), anodic aluminum oxide (AAO), α-Al2O3, nylon, microporous polymer (PIM) or polyvinylidene fluoride (PVDF); the metal layer is made of at least one of copper, aluminum, and nickel.
[0012] More preferably, the method for preparing the positive electrode includes the following steps: sputtering a gold coating onto the substrate.
[0013] Preferably, the negative electrode comprises a carbon sheet.
[0014] More preferably, the carbon sheet is an electrode sheet made of carbon material; the carbon material includes at least one of hard carbon, soft carbon, graphite, carbon powder, carbon nanotubes, carbon nanofibers, porous carbon nanosheets, graphene, and graphene oxide.
[0015] Preferably, the positive and negative electrodes are placed parallel to each other in the electrolytic cell; the positive and negative electrodes are placed below the surface of the mixed solution.
[0016] Preferably, the operating current of the electrosynthesis reaction is (-5) to (-0.1) mA.
[0017] More preferably, the operating current of the electrosynthesis reaction is (-5) to (-0.1) mA.
[0018] Preferably, the electrosynthesis reaction takes 3 to 120 minutes.
[0019] More preferably, the electrosynthesis reaction takes 5 to 40 minutes.
[0020] Preferably, the process further includes the following steps: after the reaction is complete, the obtained ZIF-90 material film is washed and dried; the drying temperature is 20~120℃.
[0021] More preferably, the drying time is 0.5-12 hours.
[0022] More preferably, the washing solution used for washing is selected from one of methanol, ethanol, isopropanol, DMF, and dichloromethane.
[0023] The second aspect of the present invention provides a ZIF-90 material prepared by the electrochemical synthesis method described in the first aspect.
[0024] Preferably, the ZIF-90 material is in the form of a crystalline film.
[0025] More preferably, the thickness of the crystal film is 0.5~5μm and the grain size is 0.5~5μm.
[0026] More preferably, the thickness of the crystal film is 0.5~2μm and the grain size is 0.5~2μm.
[0027] The third aspect of this invention provides the role of the ZIF-90 material described in the second aspect in the preparation of gas separation membranes.
[0028] Preferably, the gas separation membrane is used for the separation of propylene / propane.
[0029] The beneficial effects of this invention are: This invention provides an electrochemical synthesis method for ZIF-90 material. Compared with the traditional hydrothermal / solvothermal method for preparing ZIF-90 material, this application innovatively uses an electrochemical synthesis method to prepare ZIF-90 material. The specific beneficial effects are as follows: (1) The electrochemical synthesis method can prepare continuous and defect-free ZIF-90 polycrystalline films under mild conditions and simple operation. It can realize the in-situ growth of ZIF-90 polycrystalline films directly on the substrate without the need to add additives such as template agents; (2) The ZIF-90 film prepared by the electrochemical method exhibits a higher propylene permeation than the ZIF-90 film prepared by the traditional method, and has good application prospects. Attached Figure Description
[0030] Figure 1 This is a schematic photograph of an actual electrolytic cell mixing device.
[0031] Figure 2 The XRD pattern of the ZIF-90 film prepared in Example 1 is shown. Detailed Implementation
[0032] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from conventional commercial channels or prepared and isolated through simple synthesis; unless otherwise specified, the processes employed are conventional processes in the art.
[0033] This invention provides an electrochemical synthesis method for ZIF-90 material, comprising the following steps: A mixed solution containing imidazole-2-carboxaldehyde and a zinc source was prepared; the mixed solution was placed in an electrolytic cell, and positive and negative electrodes were inserted to carry out an electrosynthesis reaction under dual electrodes to obtain a ZIF-90 material film.
[0034] In some embodiments, the molar ratio of the zinc source to imidazole-2-carboxaldehyde is 1:(4~50).
[0035] In some specific embodiments, the molar ratio of zinc source to imidazole-2-carboxaldehyde is 1:(4~30). Another example is 1:(4~20).
[0036] Preferably, the zinc source includes at least one of zinc nitrate and zinc acetate.
[0037] In some embodiments, the method for preparing the mixed solution includes the following steps: Imidazole-2-carboxaldehyde was dissolved in methanol to prepare solution A; a zinc source was dissolved in methanol to prepare solution B; solutions A and B were mixed to prepare a mixed solution.
[0038] In some embodiments, the concentration of imidazole-2-carboxaldehyde in solution A is 0.12-1.5 mol·L⁻¹.-1 .
[0039] In some embodiments, the preparation method of solution A specifically includes: dissolving imidazole-2-carboxaldehyde in methanol solvent, heating to 30-65°C, maintaining for 5-40 min, and cooling to obtain a clear imidazole-2-carboxaldehyde solution.
[0040] In some embodiments, the positive electrode includes a substrate and a metal layer; the metal layer is disposed on the surface of the substrate; the substrate includes one of polysulfone (PSF), polyimide (PI), anodic aluminum oxide (AAO), α-Al2O3, nylon, microporous polymer (PIM), and polyvinylidene fluoride (PVDF); the metal layer is made of at least one of copper, aluminum, and nickel.
[0041] In some specific embodiments, the method for preparing the positive electrode includes the following steps: sputtering a gold coating onto the substrate.
[0042] In some embodiments, the negative electrode comprises a carbon sheet.
[0043] In some embodiments, the carbon sheet is an electrode sheet made of carbon material; the carbon material includes at least one of hard carbon, soft carbon, graphite, carbon powder, carbon nanotubes, carbon nanofibers, porous carbon nanosheets, graphene, and graphene oxide.
[0044] In some embodiments, the positive and negative electrodes are placed parallel to each other in the electrolytic cell; the positive and negative electrodes are placed below the surface of the mixed solution.
[0045] In some embodiments, the operating current of the electrosynthesis reaction is (-5) to (-0.1) mA.
[0046] In some embodiments, the operating current of the electrosynthesis reaction is (-5) to (-0.1) mA.
[0047] In some embodiments, the voltage of the electrosynthesis reaction is approximately (-4) to (-2) V.
[0048] In some embodiments, the electrosynthesis reaction takes 3 to 120 minutes.
[0049] In some embodiments, the electrosynthesis reaction takes 5 to 40 minutes.
[0050] In some embodiments, the method further includes the following steps: after the reaction is completed, the obtained ZIF-90 material film is washed and dried; the drying temperature is 20~120℃.
[0051] In some embodiments, the drying time is 0.5-12 hours.
[0052] In some embodiments, the washing solution used for washing is selected from one of methanol, ethanol, isopropanol, DMF, and dichloromethane.
[0053] In some embodiments, an electrochemical synthesis method for achieving ZIF-90 films using self-templating is provided, comprising the following steps: (1) 259.2 mg of imidazole dicarboxaldehyde was added to a glass bottle containing 15 mL of methanol solution. The glass bottle was then placed in a water bath at 55 degrees Celsius and heated for 30 min. After the time was up, it was immediately removed and cooled to room temperature for 20 min to obtain a concentration of 180 mmol / L. -1 A clear imidazole dicarboxaldehyde solution.
[0054] (2) Dissolve 98.8 mg of zinc acetate in 15 mL of methanol and sonicate for 5 min to obtain 30 mmol / L. -1 A homogeneous solution with a concentration ratio of 6:1 is obtained by pouring the solution from step (1) into step (2) to obtain a mixed solution.
[0055] (3) Insert the two electrodes into the mixed solution prepared in step (2), wherein the positive electrode of the two electrodes is gold-sprayed AAO and the negative electrode is a carbon sheet. Note that the two electrodes should preferably be placed parallel to each other in the electrolytic cell and the substrate and carbon sheet should be below the solution. Figure 1 (This is a schematic photo of the electrolytic cell mixing device.) The initial current of the potentiometer is set to -0.6 mA, and the electrosynthesis time is 10 min. After the synthesis is completed, the membrane should be removed from the electrode clamp as soon as possible.
[0056] (4) Rinse the membrane from step (3) slowly with fresh methanol 5 times. After the membrane surface is free of obvious methanol, place it in a petri dish and dry at room temperature for 24 hours to obtain ZIF-90 polycrystalline membrane.
[0057] Example 1 The electrochemical synthesis method for achieving ZIF-90 membranes through self-templating described in this embodiment comprises the following steps: (1) 259.2 mg of imidazole dicarboxaldehyde was added to a glass bottle containing 15 mL of methanol solution. The glass bottle was then placed in a water bath at 55 degrees Celsius and heated for 30 min. After the time was up, it was immediately removed and cooled to room temperature for 20 min to obtain a concentration of 180 mmol / L. -1 A clear imidazole dicarboxaldehyde solution.
[0058] (2) Dissolve 98.8 mg of zinc acetate in 15 mL of methanol and sonicate for 5 min to obtain 30 mmol / L. -1 A homogeneous solution with a concentration ratio of 6:1 is obtained by pouring the solution from step (1) into step (2) to obtain a mixed solution.
[0059] (3) Insert the two electrodes into the mixed solution prepared in step (2), wherein the positive electrode of the two electrodes is gold-sprayed AAO and the negative electrode is a carbon sheet. Note that the two electrodes should preferably be placed in parallel in the electrolytic cell and the substrate and carbon sheet should be below the solution. The initial current of the potentiometer is set to -0.6 mA and the voltage of the potentiometer is about -3 V. After the electrosynthesis is completed, it is slightly reduced to about -2.95 V (the electrochemical parameters in the following examples are also set in this way). The electrosynthesis time is 10 min. After the synthesis is completed, the membrane should be removed from the electrode clamp as soon as possible.
[0060] (4) Rinse the membrane from step (3) slowly with fresh methanol 5 times. After the membrane surface is free of obvious methanol, place it in a petri dish and dry at room temperature for 24 hours to obtain ZIF-90 polycrystalline membrane. Figure 2 The XRD pattern of the ZIF-90 membrane prepared in Example 2 proves that the ZIF-90 membrane material was successfully prepared in this example.
[0061] The ZIF-90 polycrystalline film has a thickness of approximately 1.2 micrometers and a grain size of approximately 1 micrometer.
[0062] The application of the ZIF-90 polycrystalline membrane synthesized using the self-template method in gas separation is illustrated in this embodiment. The prepared ZIF-90 membrane was sealed in an epoxy resin permeation cell for gas separation testing. A C3H6 / C3H8 (50 / 50) gas mixture was injected into the shell side of the ZIF-90 membrane for gas permeation. The mixed gas was added to the feed side of the membrane, and the permeated gas was removed from the permeate side using a scavenging gas (He). The gas separation performance was calculated after detection using an Agilent gas chromatograph 7890A.
[0063] The ZIF-90 polycrystalline membrane prepared in this invention exhibits a C3H6 flux of up to 550 GPUs, a C3H6 / C3H8 selectivity of 10, and an propylene gas permeation approximately 10 times higher than that of the ZIF-8 membrane. Furthermore, regarding the separation of propylene and propane mixed gases, the literature "Solvent-vapor-triggered crystallization of a ZIF-90 membrane with versatile separation properties towards light hydrocarbons" reports that the hydrothermally synthesized polycrystalline ZIF-90 membrane has an propylene permeation of approximately 350, while its propane permeation is lower than that of the embodiment in this invention. This result indicates that the ZIF-90 membrane prepared in this invention has good application prospects.
[0064] Example 2 The electrochemical synthesis method for achieving ZIF-90 membranes through self-templating described in this embodiment comprises the following steps: (1) 259.2 mg of imidazole dicarboxaldehyde was added to a glass bottle containing 15 mL of methanol solution. The glass bottle was then placed in a water bath at 55 degrees Celsius and heated for 30 min. After the time was up, it was immediately removed and cooled to room temperature for 20 min to obtain a concentration of 180 mmol / L. -1 A clear imidazole dicarboxaldehyde solution.
[0065] (2) Dissolve 98.8 mg of zinc acetate in 15 mL of methanol and sonicate for 5 min to obtain 30 mmol / L. -1 A homogeneous solution with a concentration ratio of 6:1 is obtained by pouring the solution from step (1) into step (2) to obtain a mixed solution.
[0066] (3) Insert the two electrodes into the mixed solution prepared in step (2), wherein the positive electrode of the two electrodes is gold-sprayed AAO and the negative electrode is a carbon sheet. Note that the two electrodes should preferably be placed in parallel in the electrolytic cell and the substrate and carbon sheet should be below the solution. The initial current of the potentiometer is set to -0.6 mA and the electrosynthesis time is 15 min. After the synthesis is completed, the membrane should be removed from the electrode clamp as soon as possible.
[0067] (4) Rinse the membrane from step (3) slowly with fresh methanol 5 times. After the membrane surface is free of obvious methanol, place it in a petri dish and dry at room temperature for 24 hours to obtain ZIF-90 polycrystalline membrane.
[0068] The application of the ZIF-90 polycrystalline membrane synthesized using the self-template method in gas separation is illustrated in this embodiment. The prepared ZIF-90 membrane was sealed in an epoxy resin permeation cell for gas separation testing. A C3H6 / C3H8 (50 / 50) gas mixture was injected into the shell side of the ZIF-90 membrane for gas permeation. The mixed gas was added to the feed side of the membrane, and the permeated gas was removed from the permeate side using a scavenging gas (He). The gas separation performance was calculated after detection using an Agilent gas chromatograph 7890A.
[0069] The ZIF-90 polycrystalline membrane prepared by this invention has a C3H6 flux of up to 460 GPUs, a C3H6 / C3H8 selectivity of 18, and an propylene gas permeation capacity that is about 9 times higher than that of the ZIF-8 membrane. This also far exceeds the hydrothermal synthesis of polycrystalline ZIF-90 membranes reported in the literature. This result indicates that the ZIF-90 membrane prepared by this invention has good application prospects.
[0070] Example 3 The electrochemical synthesis method for achieving ZIF-90 membranes through self-templating described in this embodiment comprises the following steps: (1) 259.2 mg of imidazole dicarboxaldehyde was added to a glass bottle containing 15 mL of methanol solution. The glass bottle was then placed in a water bath at 55 degrees Celsius and heated for 30 min. After the time was up, it was immediately removed and cooled to room temperature for 20 min to obtain a concentration of 180 mmol / L. -1 A clear imidazole dicarboxaldehyde solution.
[0071] (2) Dissolve 98.8 mg of zinc acetate in 15 mL of methanol and sonicate for 5 min to obtain 30 mmol / L. -1 A homogeneous solution with a concentration ratio of 6:1 is obtained by pouring the solution from step (1) into step (2) to obtain a mixed solution.
[0072] (3) Insert the two electrodes into the mixed solution prepared in step (2), wherein the positive electrode of the two electrodes is gold-sprayed AAO and the negative electrode is a carbon sheet. Note that the two electrodes should preferably be placed in parallel in the electrolytic cell and the substrate and carbon sheet should be below the solution. The initial current of the potentiometer is set to -0.6 mA and the electrosynthesis time is 15 min. After the synthesis is completed, the membrane should be removed from the electrode clamp as soon as possible.
[0073] (4) Rinse the membrane from step (3) slowly with fresh methanol 5 times. After the membrane surface is free of obvious methanol, place it in a petri dish and dry at 60 degrees for 24 hours to obtain ZIF-90 polycrystalline membrane.
[0074] The application of the ZIF-90 polycrystalline membrane synthesized using the self-template method in gas separation is illustrated in this embodiment. The prepared ZIF-90 membrane was sealed in an epoxy resin permeation cell for gas separation testing. A C3H6 / C3H8 (50 / 50) gas mixture was injected into the shell side of the ZIF-90 membrane for gas permeation. The mixed gas was added to the feed side of the membrane, and the permeated gas was removed from the permeate side using a scavenging gas (He). The gas separation performance was calculated after detection using an Agilent gas chromatograph 7890A.
[0075] The ZIF-90 polycrystalline membrane prepared by this invention has a C3H6 flux of up to 470 GPUs, a C3H6 / C3H8 selectivity of 15, and an propylene gas permeation capacity that is about 9 times higher than that of the ZIF-8 membrane. It also exceeds the hydrothermal synthesis of polycrystalline ZIF-90 membranes reported in the literature. This result indicates that the ZIF-90 membrane prepared by this invention has good application prospects.
[0076] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made 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. An electrochemical synthesis method for ZIF-90 material, characterized in that, Includes the following steps: A mixed solution containing imidazole-2-carboxaldehyde and a zinc source was prepared; the mixed solution was placed in an electrolytic cell, and positive and negative electrodes were inserted to carry out an electrosynthesis reaction under dual electrodes to obtain a ZIF-90 material film.
2. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The molar ratio of the zinc source to imidazole-2-carboxaldehyde is 1:(4~50).
3. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The zinc source includes at least one of zinc nitrate and zinc acetate.
4. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The method for preparing the mixed solution includes the following steps: Imidazole-2-carboxaldehyde was dissolved in methanol to prepare solution A; a zinc source was dissolved in methanol to prepare solution B; solutions A and B were mixed to prepare a mixed solution.
5. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The positive electrode includes a substrate and a metal layer; the metal layer is disposed on the surface of the substrate; the substrate includes one of polysulfone, polyimide, anodic aluminum oxide, α-Al2O3, nylon, microporous polymer or polyvinylidene fluoride; the metal layer is made of at least one of copper, aluminum, and nickel. And / or, the negative electrode comprises a carbon sheet.
6. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The operating current for the electrosynthesis reaction is (-5) to (-0.1) mA.
7. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The electrosynthesis reaction takes 3 to 120 minutes.
8. The electrochemical synthesis method of ZIF-90 material according to claim 1, characterized in that, The process also includes the following steps: after the reaction is complete, the obtained ZIF-90 material film is washed and dried; the drying temperature is 20~120℃.
9. ZIF-90 material prepared by the electrochemical synthesis method according to any one of claims 1-8.
10. The role of the ZIF-90 material according to claim 9 in the preparation of gas separation membranes.