Al-Ca bimetallic MOFs material and preparation method and application thereof

Abstract

The invention discloses an Al-Ca bimetallic MOFs material as well as a preparation method and application thereof. The MOFs material is formed by mutual coordination of Al, Ca and an organic ligand, in addition, uncoordinated open metal sites also exist in Al and Ca. The MOFs material disclosed by the invention contains double metals of Al and Ca at the same time, so that metal active sites are effectively increased, and the MOFs material has excellent performance in the aspects of moisture absorption and humidity control; the material has the characteristics of high porosity and large specific surface area, and is endowed with high adsorption capacity; and in addition, the uniformly dispersed non-coordinated metal sites Al and Ca have good hydrophilicity, so that the water adsorption capacity of the material is further improved. And a segmented temperature control process is adopted, so that formation and growth of MOFs crystal nucleuses in the reaction process are ensured, and the prepared MOFs material is high in crystallinity and good in dispersity.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and particularly relates to an Al-Ca bimetallic MOFs material, a preparation method thereof and an application thereof. Background Art

[0002] MOFs materials are a kind of crystalline porous materials formed by the three-dimensional extended arrangement of inorganic metal clusters and organic ligands through chemical bonds. MOFs materials combine the characteristics of traditional inorganic materials and organic materials. The inorganic metal clusters as framework connection nodes and the organic ligands playing a supporting and connecting role are flexible and variable. Starting from the topological design of reticular chemistry, MOFs materials can be rationally designed at the atomic and molecular levels to obtain porous crystalline materials with controllable composition, adjustable structure and diverse properties. Due to their developed pore structures and extremely large specific surface areas (usually greater than 1000 m 2 / g), they are generally considered to be an ideal type of gas / liquid adsorption and capture materials. Among them, the adsorption and capture of water molecules in the air is an important application direction of MOFs materials. However, for unstable MOFs materials, external water molecules can damage their structures by attacking the coordination bonds between metals and ligands, so that the MOFs materials no longer have a complete crystal structure. The water adsorption behavior of water-stable MOFs materials is also affected by three factors, namely, the chemisorption of water molecules by uncoordinated open metal sites, the physical adsorption of water molecules on the material surface and in the pores, and the capillary condensation of water vapor in the pores.

[0003] Currently, the MOF materials applied to the adsorption and capture of water molecules in the air are usually single-metal MOF materials. The water adsorption inflection point of such MOF materials is generally >30% RH. The capture of water in the air mainly relies on capillary condensation, and there are relatively few metal active sites. This moisture absorption inflection point makes it very difficult to extract water from dry air and cannot fundamentally solve the problem of obtaining and using water in dry environments. At the same time, at present, the synthesis methods of MOF materials mainly include hydro(solvent)thermal synthesis method and water bath synthesis method. In the hydro(solvent)thermal synthesis method and the water bath synthesis method during the synthesis process, metal salts and organic ligands are usually added to the solvent simultaneously, and then by applying a certain temperature and pressure, the coordination reaction between the metal and the organic ligand is promoted. During this process, in order to effectively control the reaction rate, inhibitors such as monodentate carboxylic acids are usually added to the reaction system. The inhibitor usually reacts with metal ions first, occupying the ion sites, and after a sufficient long time, the organic ligand slowly replaces the inhibitor to form a coordination with the metal ions. However, this traditional synthesis method has obvious disadvantages: (1) The reaction time is long, the product yield is low, the cost is high, and it is not suitable for batch production. (2) An inhibitor is added during the reaction process. After the reaction is completed, the inhibitor is likely to remain in the pores of the MOF material, increasing the difficulty of the post-treatment process. (3) The post-treatment solution contains a large amount of inhibitor, increasing the cost and difficulty in waste liquid treatment.

[0004] Therefore, it is of great significance to develop a MOF material with low cost, easy industrialization, strong water stability, and high water adsorption performance. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides an Al-Ca bimetallic MOF material, its preparation method and application. The MOF material selects appropriate bimetals Al and Ca, and fully exerts the synergistic effects of the uncoordinated open metal sites on the chemical adsorption of water molecules, the physical adsorption of water molecules on the surface and in the pores of the material, and the capillary condensation of water vapor in the pores, so as to improve the water adsorption capacity of the MOF material; the preparation method adopts a segmented temperature control process, and adjusts the reaction rate of the system by temperature control to improve the crystallinity of the MOF material, thereby enhancing the water stability of the MOF material and further improving the water adsorption performance of the MOF material.

[0006] Specifically, in the first aspect of the present invention, a MOF material is provided. The MOF material is formed by the coordination of Al and Ca with an organic ligand; moreover, there are uncoordinated open metal sites in Al and Ca.

[0007] Specifically, the MOF material of the present invention contains both Al and Ca bimetals. On the one hand, it effectively increases the metal active sites, enabling it to exhibit better performance in moisture absorption and control. On the other hand, Al and Ca are alternately coordinated with the organic ligand to form a polyhedral spatial structure, which not only has a high porosity but also a large specific surface area, facilitating the improvement of the adsorption capacity of the MOF material. At the same time, there are uncoordinated open metal sites in Al and Ca. Due to the good hydrophilicity of Al and Ca, the water adsorption capacity of the material can be further enhanced. Therefore, the Al-Ca bimetallic MOF material of the present invention fully utilizes the synergistic effects of the uncoordinated open metal sites on the chemisorption of water molecules, the physical adsorption of water molecules on the material surface and in the pores, and the capillary condensation of water vapor in the pores, thereby greatly improving the water adsorption performance of the material.

[0008] As a further improvement of the above solution, in the MOF material, the molar ratio of Al to Ca is (0.25 - 10):1. The present invention has found through research that the dosage relationship between Al and Ca will directly affect the water adsorption capacity of the MOF material. By controlling the dosages of the two metals within a suitable range, their synergistic effects can be exerted to achieve the best water adsorption performance of the MOF material.

[0009] According to some embodiments of the present invention, in the MOF material, the molar ratio of Al to Ca is (0.25 - 5):1; further, the molar ratio of Al to Ca is (0.25 - 1):1. By preferably a more suitable dosage relationship between the two metals, better water adsorption performance of the MOF material can be obtained.

[0010] As a further improvement of the above solution, in the MOF material, the molar ratio of Al to the organic ligand is (0.1 - 1.5):1. By controlling the dosage relationship between Al and the organic ligand, the relationship between the metal and the organic ligand in the MOF material can be controlled, enabling a part of the metal to be coordinated with the organic ligand to form a MOF material with a specific polyhedral spatial structure, and the other uncoordinated open metal sites to be dispersed in the spatial structure of the MOF material. The metal sites in different positions jointly perform the water adsorption function.

[0011] According to some embodiments of the present invention, in the MOF material, the molar ratio of Al to the organic ligand is (0.1 - 0.8):1; further, the molar ratio of Al to the organic ligand is (0.1 - 0.5):1. By preferably a more suitable dosage relationship between Al and the organic ligand, better water adsorption performance of the MOF material can be obtained.

[0012] As a further improvement of the above solution, the water adsorption capacity of the MOFs material is 0.56 - 1.10 g / g. Due to the selection of appropriate Al and Ca bimetals in the MOFs material of the present invention, and by giving full play to the synergistic effects of the uncoordinated open metal sites on the chemisorption of water molecules, the physical adsorption of water molecules on the surface and in the pores of the material, and the capillary condensation of water vapor in the pores, the water adsorption capacity of the MOFs material is effectively improved, making it have a better water adsorption capacity compared to conventional water adsorption materials.

[0013] As a further improvement of the above solution, the organic ligand is one or two of bidentate ligands and multidentate ligands. The selection of the organic ligand is mainly determined by the MOFs material to be synthesized, so as to be more conducive to the formation of MOFs crystals.

[0014] According to some embodiments of the present invention, the organic ligand is selected from at least one of oxalic acid, malonic acid, succinic acid, suberic acid, 2,2'-biphenyldicarboxylic acid, fumaric acid, 1,2,4-butanetricarboxylic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, triethyl 1,3,5-benzenetricarboxylate, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 3,3',5,5'-biphenyltetracarboxylic acid, 1,2,4-butanetricarboxylic acid, and 1,2,3-propanetricarboxylic acid.

[0015] The second aspect of the present invention provides a preparation method of the MOFs material according to any one of the technical solutions of the first aspect of the present invention, including the following steps:

[0016] Adding a metal salt solution and an organic ligand solution into a reaction kettle, and while stirring, performing temperature control treatment on the reaction kettle to obtain the MOFs material; the metal salt solution contains an aluminum metal salt and a calcium metal salt.

[0017] Specifically, when preparing the MOFs material of the present invention, a segmented temperature control process is adopted. Its main purpose is to regulate the reaction rate of the system by controlling the temperature, and at the same time ensure the formation and growth of MOFs crystal nuclei during the reaction process. The traditional one-step hydrothermal method has the following problems: if the temperature is too low, the reaction cannot proceed normally, and the environmental temperature is too low to reach the activation energy required for the reaction, resulting in more by-products and unreacted materials during the reaction process, thus leading to a decline in material performance; if the temperature is too high, the reaction rate is uncontrollable, and the reaction products are prone to quickly form a plate, hindering the further occurrence of the reaction; at the same time, when the environmental temperature is too high, there is an interpenetrating structure in the pores of the formed MOFs material (i.e., another MOF grows interpenetratingly in one MOF lattice), and this structure will greatly reduce the specific surface area of the MOFs material, thereby leading to a decline in the water adsorption performance of the material.

[0018] Meanwhile, the MOFs material prepared by the segmented temperature control process of the present invention not only has high crystallinity, but also has good dispersibility and no obvious agglomeration, making the form of the MOFs material more diverse during the forming application process. In addition, by controlling the temperature to adjust the reaction rate of the system, without adding any inhibitors, it is beneficial to reduce costs and pollution.

[0019] As a further improvement of the above solution, the molar concentration of the metal salt solution is 0.001 - 50 mol / L.

[0020] According to some embodiments of the present invention, the molar concentration of the metal salt solution is 0.05 - 10 mol / L; further, the molar concentration of the metal salt solution is 0.1 - 0.4 mol / L.

[0021] As a further improvement of the above solution, the molar concentration of the organic ligand is 0.01 - 30 mol / L.

[0022] According to some embodiments of the present invention, the molar concentration of the organic ligand is 0.1 - 5 mol / L; further, the molar concentration of the organic ligand is 0.2 - 0.5 mol / L.

[0023] As a further improvement of the above solution, the volume ratio of the metal salt solution to the organic ligand solution is (0.1 - 10):1.

[0024] According to some embodiments of the present invention, the volume ratio of the metal salt solution to the organic ligand solution is (0.5 - 5):1; further, the volume ratio of the metal salt solution to the organic ligand solution is (0.8 - 1.5):1.

[0025] As a further improvement of the above solution, the aluminum metal salt is selected from at least one of aluminum nitrate, aluminum carbonate, aluminum bicarbonate, aluminum sulfate, aluminum chloride, aluminum oxychloride, and hydrates of the above substances. The aluminum metal salt mainly provides aluminum metal sites for the MOFs material, and the present invention finds that the aluminum-based MOFs material has good water stability and water adsorption performance.

[0026] As a further improvement of the above solution, the calcium metal salt is selected from at least one of calcium nitrate, calcium carbonate, calcium bicarbonate, calcium sulfate, calcium chloride, calcium oxychloride, and hydrates of the above substances. The calcium metal salt mainly provides calcium metal sites for the MOFs material. At the same time, the introduction of calcium metal sites can cooperate with aluminum metal sites to further improve the activity of the aluminum-based MOFs material and enhance its performance in moisture absorption and humidity control.

[0027] As a further improvement of the above solution, the solvents of the metal salt solution and the organic ligand solution are independently selected from at least one of water, methanol, ethanol, propanol, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide. The metal salt and organic ligand of the present invention have good solubility in these solvents.

[0028] As a further improvement of the above solution, the stirring speed is 100 - 500 rpm.

[0029] According to some embodiments of the present invention, the stirring speed is 200 - 400 rpm; further, the stirring speed is 150 - 300 rpm.

[0030] As a further improvement of the above solution, the process of temperature control treatment is as follows: first, heat up to 30 - 50 °C and keep warm for 10 - 60 min; then heat up to 60 - 80 °C and keep warm for 5 - 60 min; finally, heat up to 100 - 150 °C and keep warm for 5 - 60 min.

[0031] According to some embodiments of the present invention, the initial temperature of the reaction kettle is 0 - 10 °C.

[0032] According to some embodiments of the present invention, the initial temperature of the reaction kettle is 5 - 10 °C.

[0033] According to some embodiments of the present invention, the heating rate of the reaction kettle is 1 - 15 °C / min.

[0034] According to some embodiments of the present invention, the heating rate of the reaction kettle is 8 - 12 °C / min.

[0035] Specifically, in the present invention, at a certain heating rate, by gradually heating in segments and keeping warm for a certain time in each temperature segment, the speed of the coordination reaction is reduced, the crystal ordered growth time is prolonged, which is beneficial to improving the crystallinity of the MOFs material, thereby improving its moisture absorption performance, and the reaction process is mild and controllable, with a high space-time yield.

[0036] According to some embodiments of the present invention, the process of temperature control treatment is as follows: first, heat up to 30 - 40 °C and keep warm for 30 - 60 min; then heat up to 65 - 70 °C and keep warm for 35 - 45 min; finally, heat up to 100 - 100 °C and keep warm for 20 - 60 min.

[0037] As a further improvement of the above solution, after the temperature control treatment, it further includes the steps of filtration, washing, and drying. The washing agent used for washing is at least one of water, ethanol, and methanol, which is mainly used to remove the remaining reactants.

[0038] According to some embodiments of the present invention, the washing agent used for washing is water.

[0039] As a further improvement of the above solution, the number of washing times is 2 - 6 times. The purpose of repeated washing is to completely remove the remaining reactants.

[0040] According to some embodiments of the present invention, the number of washing times is 2 - 4 times.

[0041] As a further improvement of the above solution, the drying temperature is 50 - 150 °C, which is mainly used to remove the residual washing agent.

[0042] According to some embodiments of the present invention, the drying temperature is 110 - 130 °C.

[0043] As a further improvement of the above solution, the drying time is 2 - 8 hours. Drying for a certain time at a certain temperature to completely volatilize the washing agent.

[0044] According to some embodiments of the present invention, the drying time is 5 - 7 hours.

[0045] The third aspect of the present invention provides a water molecule adsorption material, which includes the MOFs material according to any technical solution of the first aspect of the present invention, or the MOFs material prepared by the preparation method according to any technical solution of the second aspect of the present invention. Since the water molecule adsorption material includes the MOFs material of the above technical solution, it has all the beneficial effects that the MOFs material can achieve. To avoid repetition, it will not be elaborated here.

[0046] Specifically, the MOFs material of the present invention has the advantages of low humidity response point, large moisture absorption capacity, and simple dehumidification conditions, and can be applied to water extraction in deserts, seawater desalination, home humidity control or production workshop humidity control.

[0047] According to some embodiments of the present invention, the production workshop is a production workshop for lithium battery diaphragms or electronic device packaging.

[0048] The fourth aspect of the present invention provides an air treatment device, which includes the MOFs material according to any technical solution of the first aspect of the present invention, or the water molecule adsorption material according to the third aspect of the present invention. Since the air treatment device includes the MOFs material or the water molecule adsorption material of the above technical solution, it has all the beneficial effects that the MOFs material or the water molecule adsorption material can achieve. To avoid repetition, it will not be elaborated here.

[0049] The above technical solutions of the present invention have at least the following technical effects or advantages compared with the prior art:

[0050] (1) The MOF material of the present invention contains both Al and Ca bimetals, effectively increasing the metal active sites, making it have excellent performance in moisture absorption and control; and this material has the characteristics of high porosity and large specific surface area, endowing it with a high adsorption capacity; in addition, the uncoordinated open metal sites Al and Ca have good hydrophilicity, further enhancing the water adsorption ability of the material. Therefore, the Al-Ca bimetal MOF material of the present invention gives full play to the synergistic effects of the uncoordinated open metal sites on the chemical adsorption of water molecules, the physical adsorption of water molecules on the material surface and in the pores, and the capillary condensation of water vapor in the pores, thus greatly improving the water adsorption performance of the MOF material.

[0051] (2) When preparing the MOF material of the present invention, a segmented temperature control process is adopted to adjust the reaction rate of the system by controlling the temperature, ensuring the formation and growth of MOF crystal nuclei during the reaction process, so that the prepared MOF material not only has high crystallinity and good dispersibility, but also does not need to add any inhibitors, which is beneficial to reducing costs and pollution.

[0052] (3) For the MOF material prepared by the present invention, when tested by normal temperature variable pressure water adsorption, the water adsorption capacity can reach 0.56 - 1.1 g / g. Description of the Drawings

[0053] Figure 1 SEM image of the Al-Ca bimetal MOF material prepared in Example 1;

[0054] Figure 2 SEM image of the Al-Ca bimetal MOF material prepared in Comparative Example 2. Detailed Description of the Invention

[0055] The following describes the present invention in detail with reference to the embodiments for the understanding of those skilled in the art. It is necessary to specifically point out here that the embodiments are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art, based on the above invention content, make non-essential improvements and adjustments to the present invention, which should still fall within the protection scope of the present invention. At the same time, for the raw materials not detailed below, they are all commercially available products; for the process steps or preparation methods not detailed, they are all process steps or preparation methods known to those skilled in the art.

[0056] In the first aspect of the embodiments of the present invention, a MOF material is provided. This MOF material is formed by the coordination of Al and Ca with organic ligands; and there are also uncoordinated open metal sites in Al and Ca.

[0057] The MOF material of the present invention contains both Al and Ca bimetals. On the one hand, it effectively increases the metal active sites, enabling it to exhibit better performance in moisture absorption and control. On the other hand, Al and Ca are alternately coordinated with the organic ligand to form a polyhedral spatial structure, which not only has a high porosity but also a large specific surface area, facilitating the improvement of the adsorption capacity of the MOF material. At the same time, there are uncoordinated open metal sites Al and Ca in the polyhedral spatial structure. Due to the good hydrophilicity of Al and Ca, the water adsorption capacity of the material can be further enhanced. Therefore, the Al-Ca bimetallic MOF material of the present invention fully utilizes the synergistic effects of the uncoordinated open metal sites on the chemisorption of water molecules, the physical adsorption of water molecules on the surface and in the pores of the material, and the capillary condensation of water vapor in the pores, thus greatly improving the water adsorption performance of the material.

[0058] According to some embodiments of the present invention, in the MOF material, the molar ratio of Al to Ca is (0.25 - 10):1. For example, the molar ratio of Al to Ca is (0.25 - 5):1. The present invention has found through research that the dosage relationship between Al and Ca will directly affect the water adsorption capacity of the MOF material. By controlling the dosages of the two metals within a suitable range, their synergistic effects can be utilized to achieve the best water adsorption performance of the MOF material.

[0059] According to some embodiments of the present invention, in the MOF material, the molar ratio of Al to Ca is (0.25 - 1):1. By preferably a more suitable dosage relationship between the two metals, better water adsorption performance of the MOF material can be obtained.

[0060] According to some embodiments of the present invention, in the MOF material, the molar ratio of Al to the organic ligand is (0.1 - 1.5):1. For example, the molar ratio of Al to the organic ligand is (0.1 - 0.8):1. By controlling the dosage relationship between Al and the organic ligand, the relationship between the metal and the organic ligand in the MOF material can be controlled, enabling a part of the metal to coordinate with the organic ligand to form a MOF material with a specific polyhedral spatial structure, and the other uncoordinated open metal sites are dispersed in the spatial structure of the MOF material. The metals in different positions jointly perform the water adsorption function.

[0061] According to some embodiments of the present invention, in the MOF material, the molar ratio of Al to the organic ligand is (0.1 - 0.5):1. By preferably a more suitable dosage relationship between Al and the organic ligand, better water adsorption performance of the MOF material can be obtained.

[0062] According to some embodiments of the present invention, the water adsorption capacity of the MOFs material is 0.56 - 1.10 g / g. For example, the water adsorption capacity of the MOFs material is 0.71 - 1.10 g / g. Due to the selection of appropriate Al and Ca bimetals in the MOFs material of the present invention, and by giving full play to the synergistic effects of the uncoordinated open metal sites on the chemisorption of water molecules, the physical adsorption of water molecules on the material surface and in the pores, and the capillary condensation of water vapor in the pores, the water adsorption capacity of the MOFs material is effectively improved, making it have a better water adsorption capacity than conventional adsorption materials.

[0063] According to some embodiments of the present invention, the organic ligand is one or two of bidentate ligands and polydentate ligands. The selection of the organic ligand is mainly determined by the MOFs material to be synthesized, in order to more facilitate the formation of MOFs crystals.

[0064] According to some embodiments of the present invention, the organic ligand is selected from at least one of oxalic acid, malonic acid, succinic acid, suberic acid, 2,2'-biphenyldicarboxylic acid, fumaric acid, 1,2,4-butanetricarboxylic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, triethyl 1,3,5-benzenetricarboxylate, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 3,3',5,5'-biphenyltetracarboxylic acid, 1,2,4-butanetricarboxylic acid, and 1,2,3-propanetricarboxylic acid.

[0065] The second aspect of the embodiments of the present invention provides a preparation method of the MOFs material according to any one of the technical solutions of the first aspect of the present invention, including the following steps:

[0066] Add the metal salt solution and the organic ligand solution into a reaction kettle, and while stirring, perform temperature control treatment on the reaction kettle to obtain the MOFs material; the metal salt solution contains an aluminum metal salt and a calcium metal salt.

[0067] When preparing the MOFs material of the present invention, a segmented temperature control process is adopted. Its main purpose is to adjust the reaction rate of the system by controlling the temperature, and at the same time ensure the formation and growth of MOFs crystal nuclei during the reaction process. The traditional one-step hydrothermal method has the following problems: if the temperature is too low, the reaction cannot proceed normally, and the environmental temperature is too low to reach the activation energy required for the reaction, resulting in more by-products and unreacted materials during the reaction process, thus leading to a decline in material performance; if the temperature is too high, the reaction rate is uncontrollable, and the reaction products are prone to quickly form a plate, hindering the further occurrence of the reaction; at the same time, when the environmental temperature is too high, there is an interpenetrating structure in the formed MOFs pores (i.e., another MOF grows interpenetratingly in one MOF lattice), and this structure will greatly reduce the specific surface area of the MOFs material, thus also leading to a decline in material performance.

[0068] Meanwhile, the MOFs material prepared by the segmented temperature control process of the present invention not only has high crystallinity, but also has good dispersibility and no obvious agglomeration, making the form of the MOFs material more diverse during the forming application process. In addition, by controlling the temperature to adjust the reaction rate of the system, without adding any inhibitors, it is beneficial to reduce costs and pollution.

[0069] According to some embodiments of the present invention, the molar concentration of the metal salt solution is 0.001 - 50 mol / L. For example, the molar concentration of the metal salt solution is 0.05 - 10 mol / L; the molar concentration of the metal salt solution is 0.1 - 0.4 mol / L.

[0070] According to some embodiments of the present invention, the molar concentration of the organic ligand is 0.01 - 30 mol / L. For example, the molar concentration of the organic ligand is 0.1 - 5 mol / L; the molar concentration of the organic ligand is 0.2 - 0.5 mol / L.

[0071] According to some embodiments of the present invention, the volume ratio of the metal salt solution to the organic ligand solution is (0.1 - 10):1. For example, the volume ratio of the metal salt solution to the organic ligand solution is (0.5 - 5):1; the volume ratio of the metal salt solution to the organic ligand solution is (0.8 - 1.5):1.

[0072] According to some embodiments of the present invention, the aluminum metal salt is selected from at least one of aluminum nitrate, aluminum carbonate, aluminum bicarbonate, aluminum sulfate, aluminum chloride, aluminum oxychloride, and hydrates of the above substances. The aluminum metal salt mainly provides aluminum metal sites for the MOFs material, and the present invention finds that the aluminum-based MOFs material has good water stability and water adsorption performance.

[0073] According to some embodiments of the present invention, the calcium metal salt is selected from at least one of calcium nitrate, calcium carbonate, calcium bicarbonate, calcium sulfate, calcium chloride, calcium oxychloride, and hydrates of the above substances. The calcium metal salt mainly provides calcium metal sites for the MOFs material, and at the same time, the introduction of calcium metal sites can cooperate with aluminum metal sites to further improve the activity of the aluminum-based MOFs material and enhance its performance in moisture absorption and humidity control.

[0074] According to some embodiments of the present invention, the solvents of the metal salt solution and the organic ligand solution are independently selected from at least one of water, methanol, ethanol, propanol, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide. The metal salts and organic ligands of the present invention have good solubility in these solvents.

[0075] According to some embodiments of the present invention, the stirring speed is 100 - 500 rpm. For example, the stirring speed is 200 - 400 rpm; the stirring speed is 150 - 300 rpm.

[0076] According to some embodiments of the present invention, the process of temperature control treatment is as follows: first, heat up to 30 - 50 °C and keep warm for 10 - 60 min; then heat up to 60 - 80 °C and keep warm for 5 - 60 min; finally, heat up to 100 - 150 °C and keep warm for 5 - 60 min.

[0077] According to some embodiments of the present invention, the initial temperature of the reaction kettle is 0 - 10 °C.

[0078] According to some embodiments of the present invention, the initial temperature of the reaction kettle is 5 - 10 °C.

[0079] According to some embodiments of the present invention, the heating rate of the reaction kettle is 1 - 15 °C / min.

[0080] According to some embodiments of the present invention, the heating rate of the reaction kettle is 8 - 12 °C / min.

[0081] In the present invention, at a certain heating rate, by gradually heating in stages and keeping warm for a certain period of time in each temperature stage, the rate of the coordination reaction is reduced, the time for the ordered growth of crystals is prolonged, which is beneficial to improving the crystallinity of the MOFs material, thereby improving its moisture absorption performance, and the reaction process is mild and controllable, with a high space-time yield.

[0082] According to some embodiments of the present invention, the process of temperature control treatment is as follows: first, heat up to 30 - 40 °C and keep warm for 30 - 60 min; then heat up to 65 - 70 °C and keep warm for 35 - 45 min; finally, heat up to 100 - 100 °C and keep warm for 20 - 60 min.

[0083] According to some embodiments of the present invention, after the temperature control treatment, it further includes the steps of filtration, washing, and drying. Among them: the washing agent used for washing is at least one of water, ethanol, and methanol, mainly used to remove the remaining reactants.

[0084] According to some embodiments of the present invention, the washing agent used for washing is water.

[0085] According to some embodiments of the present invention, the number of washing times is 2 - 6 times. For example, the number of washing times is 2 - 4 times. The purpose of repeated washing is to completely remove the remaining reactants.

[0086] According to some embodiments of the present invention, the drying temperature is 50 - 150 °C. For example, the drying temperature is 110 - 130 °C. It is mainly used to remove the residual washing agent.

[0087] According to some embodiments of the present invention, the drying time is 2 - 8 hours. For example, the drying time is 5 - 7 hours. Drying at a certain temperature for a certain period of time to completely volatilize the washing agent.

[0088] In the third aspect of the embodiments of the present invention, a water molecule adsorption material is provided. The water molecule adsorption material includes the MOFs material of any technical solution in the first aspect of the present invention, or the MOFs material prepared by the preparation method of any technical solution in the second aspect of the present invention. Since the water molecule adsorption material includes the MOFs material of the above technical solutions, it has all the beneficial effects that the MOFs material can achieve. To avoid repetition, it will not be elaborated here.

[0089] The MOFs material of the present invention has the advantages of low humidity response point, large moisture absorption capacity, and simple dehumidification conditions, and can be applied to water extraction in deserts, seawater desalination, home humidity control or production workshop humidity control.

[0090] According to some embodiments of the present invention, the production workshop is a production workshop for lithium battery diaphragms or electronic device encapsulation.

[0091] In the fourth aspect of the embodiments of the present invention, an air treatment device is provided, which includes the MOFs material of any technical solution in the first aspect of the present invention, or the water molecule adsorption material in the third aspect of the present invention. Since the air treatment device includes the MOFs material or the water molecule adsorption material of the above technical solutions, it has all the beneficial effects that the MOFs material or the water molecule adsorption material can achieve. To avoid repetition, it will not be elaborated here.

[0092] Example 1

[0093] A preparation method of an Al-Ca bimetallic MOFs material includes the following steps:

[0094] (1) Add 3 mol of aluminum chloride and 3.5 mol of calcium chloride to 20 L of water. After fully dissolving, solution A is obtained;

[0095] (2) Add 7 mol of fumaric acid and 14 mol of sodium hydroxide to 25 L of water to obtain solution B; the main purpose of adding sodium hydroxide is to deprotonate fumaric acid and increase the solubility of fumaric acid in a low-temperature water bath;

[0096] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle at the same time. The reaction kettle is controlled by a mold temperature machine in a water bath, with an initial temperature of 5 °C, and the stirring speed of the reaction kettle is adjusted to 150 rpm. In the first stage of the reaction process, the reaction kettle is heated to 35 °C during stirring and reacted for 60 min; in the second stage, the reaction kettle is heated to 65 °C during stirring and reacted for 40 min; in the third stage, the reaction kettle is heated to 100 °C during stirring and reacted for 20 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, the reaction product is filtered by suction and washed with water 3 times, and then placed in a blast drying oven at 120 °C for drying for 6 hours to obtain the Al-Ca bimetallic MOFs material of this example.

[0097] The SEM image of the Al-Ca bimetallic MOF material prepared in Example 1 is as follows Figure 1 shown. It can be seen from Figure 1 this that the MOF material is a flaky crystal with high crystallinity and good dispersibility, and no agglomeration phenomenon is observed.

[0098] Example 2

[0099] A preparation method of an Al-Ca bimetallic MOF material comprises the following steps:

[0100] (1) 5 mol of aluminum nitrate and 5 mol of calcium nitrate are added to 30 L of water. After complete dissolution, solution A is obtained;

[0101] (2) 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid is added to 20 L of water to obtain solution B;

[0102] (3) Solution A prepared in step (1) and solution B prepared in step (2) are simultaneously added to a reaction kettle. The reaction kettle is temperature-controlled by a water bath of a mold temperature controller. The initial temperature is 10 °C, and the stirring speed of the reaction kettle is adjusted to 300 rpm. In the first stage of the reaction process, the temperature of the reaction kettle is raised to 40 °C during stirring, and the reaction lasts for 30 min; in the second stage, the temperature of the reaction kettle is raised to 70 °C during stirring, and the reaction lasts for 40 min; in the third stage, the temperature of the reaction kettle is raised to 120 °C during stirring, and the reaction lasts for 60 min. During the reaction process, the heating rate is 10 °C / min. After the reaction is completed, the reaction product is filtered by suction and washed with water three times, and then placed in a blast drying oven at 120 °C for drying for 6 hours to obtain the Al-Ca bimetallic MOF material of this example.

[0103] Example 3

[0104] A preparation method of an Al-Ca bimetallic MOF material comprises the following steps:

[0105] (1) 5 mol of aluminum nitrate and 1 mol of calcium nitrate are added to 30 L of water. After complete dissolution, solution A is obtained;

[0106] (2) 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid is added to 20 L of water to obtain solution B;

[0107] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle simultaneously. The reaction kettle is temperature-controlled by a water bath using a mold temperature controller, with an initial temperature of 10 °C, and adjust the stirring speed of the reaction kettle to 300 rpm. In the first stage of the reaction process, during stirring, heat up the reaction kettle to 40 °C and react for 30 min; in the second stage, during stirring, heat up the reaction kettle to 70 °C and react for 40 min; in the third stage, during stirring, heat up the reaction kettle to 120 °C and react for 60 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, filter the reaction product by suction and wash it with water 3 times, then place it in a blast drying oven at 120 °C and dry for 6 hours to obtain the Al-Ca bimetallic MOFs material of this example.

[0108] Example 4

[0109] A preparation method of an Al-Ca bimetallic MOFs material, comprising the following steps:

[0110] (1) Put 10 mol of aluminum nitrate and 1 mol of calcium nitrate into 30 L of water, and after complete dissolution, obtain solution A;

[0111] (2) Put 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid into 20 L of water to obtain solution B;

[0112] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle simultaneously. The reaction kettle is temperature-controlled by a water bath using a mold temperature controller, with an initial temperature of 10 °C, and adjust the stirring speed of the reaction kettle to 300 rpm. In the first stage of the reaction process, during stirring, heat up the reaction kettle to 40 °C and react for 30 min; in the second stage, during stirring, heat up the reaction kettle to 70 °C and react for 40 min; in the third stage, during stirring, heat up the reaction kettle to 120 °C and react for 60 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, filter the reaction product by suction and wash it with water 3 times, then place it in a blast drying oven at 120 °C and dry for 6 hours to obtain the Al-Ca bimetallic MOFs material of this example.

[0113] Example 5

[0114] A preparation method of an Al-Ca bimetallic MOFs material, comprising the following steps:

[0115] (1) Put 1 mol of aluminum nitrate and 4 mol of calcium nitrate into 30 L of water, and after complete dissolution, obtain solution A;

[0116] (2) Put 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid into 20 L of water to obtain solution B;

[0117] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle simultaneously. The reaction kettle is temperature-controlled by a mold temperature machine in a water bath. The initial temperature is 10 °C, and the stirring speed of the reaction kettle is adjusted to 300 rpm. In the first stage of the reaction process, during stirring, the temperature of the reaction kettle is raised to 40 °C and reacted for 30 min; in the second stage, during stirring, the temperature of the reaction kettle is raised to 70 °C and reacted for 40 min; in the third stage, during stirring, the temperature of the reaction kettle is raised to 120 °C and reacted for 60 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, the reaction product is filtered by suction and washed with water 3 times, and then placed in a blast drying oven at 120 °C for drying for 6 hours to obtain the Al-Ca bimetallic MOFs material of this example.

[0118] Comparative Example 1

[0119] A preparation method of an Al MOFs material includes the following steps:

[0120] (1) Put 3 mol of aluminum chloride into 20 L of water. After fully dissolving, solution A is obtained;

[0121] (2) Put 7 mol of fumaric acid and 14 mol of sodium hydroxide into 25 L of water to obtain solution B. The main purpose of adding sodium hydroxide is to deprotonate fumaric acid and increase the solubility of fumaric acid in a low-temperature water bath;

[0122] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle simultaneously. The reaction kettle is temperature-controlled by a mold temperature machine in a water bath. The initial temperature is 5 °C, and the stirring speed of the reaction kettle is adjusted to 150 rpm. In the first stage of the reaction process, during stirring, the temperature of the reaction kettle is raised to 35 °C and reacted for 60 min; in the second stage, during stirring, the temperature of the reaction kettle is raised to 65 °C and reacted for 40 min; in the third stage, during stirring, the temperature of the reaction kettle is raised to 100 °C and reacted for 20 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, the reaction product is filtered by suction and washed with water 3 times, and then placed in a blast drying oven at 120 °C for drying for 6 hours to obtain the Al MOFs material of this comparative example.

[0123] Comparative Example 2

[0124] A preparation method of an Al-Ca bimetallic MOFs material includes the following steps:

[0125] (1) Put 5 mol of aluminum nitrate and 5 mol of calcium nitrate into 30 L of water. After fully dissolving, solution A is obtained;

[0126] (2) Put 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid into 20 L of water to obtain solution B;

[0127] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle simultaneously. The reaction kettle is temperature-controlled by a water bath using a mold temperature controller, with an initial temperature of 10 °C. Adjust the stirring speed of the reaction kettle to 300 rpm. During the reaction process, no stage temperature control is carried out, that is, the temperature of the reaction kettle is raised to 70 °C during stirring, and the reaction lasts for 130 min; the heating rate during the reaction process is 10 °C / min. After the reaction is completed, filter the reaction product by suction and wash it with water 3 times, then place it in a blast drying oven at 120 °C and dry it for 6 hours to obtain the Al-Ca bimetallic MOFs material of this comparative example.

[0128] The SEM image of the Al-Ca bimetallic MOFs material prepared in Comparative Example 2 is as Figure 2 shown. It can be seen from Figure 2 that the crystallinity of this MOFs material is poor, the dispersibility is poor, and the agglomeration phenomenon is serious.

[0129] Comparative Example 3

[0130] A preparation method of an Al-Ca bimetallic MOFs material includes the following steps:

[0131] (1) Put 15 mol of aluminum nitrate and 1 mol of calcium nitrate into 30 L of water, and after fully dissolving, obtain solution A;

[0132] (2) Put 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid into 20 L of water to obtain solution B;

[0133] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle simultaneously. The reaction kettle is temperature-controlled by a water bath using a mold temperature controller, with an initial temperature of 10 °C. Adjust the stirring speed of the reaction kettle to 300 rpm. In the first stage of the reaction process, raise the temperature of the reaction kettle to 40 °C during stirring and react for 30 min; in the second stage, raise the temperature of the reaction kettle to 70 °C during stirring and react for 40 min; in the third stage, raise the temperature of the reaction kettle to 120 °C during stirring and react for 60 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, filter the reaction product by suction and wash it with water 3 times, and then place it in a blast drying oven at 120 °C and dry it for 6 hours to obtain the Al-Ca bimetallic MOFs material of this comparative example.

[0134] Comparative Example 4

[0135] A preparation method of an Al-Ca bimetallic MOFs material includes the following steps:

[0136] (1) Put 1 mol of aluminum nitrate and 10 mol of calcium nitrate into 30 L of water, and after fully dissolving, obtain solution A;

[0137] (2) Add 8 mol of 3,3’,5,5’-biphenyltetracarboxylic acid into 20 L of water to obtain solution B;

[0138] (3) Add the solution A prepared in step (1) and the solution B prepared in step (2) into the reaction kettle at the same time. The reaction kettle is controlled by a mold temperature machine for water bath, with the initial temperature of 10 °C, and the stirring speed of the reaction kettle is adjusted to 300 rpm. In the first stage of the reaction process, during stirring, the temperature of the reaction kettle is raised to 40 °C and reacted for 30 min; in the second stage, during stirring, the temperature of the reaction kettle is raised to 70 °C and reacted for 40 min; in the third stage, during stirring, the temperature of the reaction kettle is raised to 120 °C and reacted for 60 min; during the reaction process, the heating rate is 10 °C / min; after the reaction is completed, the reaction product is filtered by suction and washed with water 3 times, and then placed in a blast drying oven at 120 °C for drying for 6 hours to obtain the Al-Ca bimetallic MOFs material of this comparative example.

[0139] Performance test

[0140] Isothermal variable-pressure water adsorption is a basic means and method for characterizing and evaluating hygroscopic materials. In this invention, a gravimetric vapor sorption analyzer produced by Micromeritics Instrument Corporation of the United States, with the model of ASAP 2020PLUS, is used to conduct isothermal variable-pressure water adsorption tests on the MOFs material samples prepared in Examples 1-5 and Comparative Examples 1-4. The specific test conditions are as follows: at 298 K, water adsorption tests are conducted on each sample. Before the test, the samples are vacuum desorbed at 150 °C for 8 hours, and the water adsorption capacity of the samples is calculated according to the gravimetric method. The calculation formula is shown in Equation (1):

[0141] wt%=(m 水 / m 样 )×100% (1)

[0142] In Equation (1), wt%: the water adsorption capacity of the sample; m 水 : the weight of water absorbed by the sample, in g; m 样 : the weight of the measured sample, in g.

[0143] The water adsorption capacities of the MOFs material samples prepared in Examples 1-5 and Comparative Examples 1-4 are shown in Table 1.

[0144] Table 1:

[0145]

[0146]

[0147] As can be seen from Table 1, for the MOFs materials prepared in Examples 1-5 of this invention, their water adsorption capacities are 0.56 - 1.1 g / g, showing good water adsorption performance.

[0148] The difference between Comparative Example 1 and Example 1 is only that the MOF material prepared from single-metal aluminum in Comparative Example 1 has a significantly lower water adsorption capacity than the MOF material prepared from Al-Ca bimetal in Example 1.

[0149] The difference between Comparative Example 2 and Example 2 is only that during the preparation of the MOF material in Comparative Example 2, staged temperature control was not adopted, resulting in a low crystallinity of the MOF material, and agglomeration and caking phenomena occurred. The water adsorption capacity also decreased significantly compared to the MOF material prepared in Example 2.

[0150] The differences between Comparative Examples 3-4 and Examples 4-5 are only that the molar ratios of aluminum metal salt and calcium metal salt are different. Moreover, since the molar ratios of aluminum metal salt and calcium metal salt in Examples 3-4 are not within the range of (0.25-10):1, the water adsorption capacity of the prepared MOF materials decreased significantly compared to Examples 4-5, indicating that the appropriate dosage relationship between aluminum metal salt and calcium metal salt has a great influence on the water adsorption capacity of MOF materials.

[0151] For those of ordinary skill in the art to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made without the need for creative labor. Therefore, any simple improvements made by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention. The above embodiments are the preferred embodiments of the present invention, and all processes similar to the present invention and equivalent changes made thereto should fall within the protection scope of the present invention.

Claims

1. A MOFs material, It is characterized in that The MOFs material is formed by mutual coordination of Al and Ca with organic ligands; and there are uncoordinated open metal sites in Al and Ca.

2. The MOFs material according to claim 1, It is characterized in that In the MOFs material, the molar ratio of Al to Ca is (0.25-10):

1.

3. The MOFs material according to claim 1 or 2, It is characterized in that In the MOFs material, the molar ratio of Al to the organic ligand is (0.1-1.5):

1.

4. The MOFs material according to claim 1, It is characterized in that The water adsorption capacity of the MOFs material is 0.56-1.10 g / g.

5. The MOFs material according to claim 1, It is characterized in that The organic ligand is one or both of a bidentate ligand and a multidentate ligand.

6. The MOFs material according to claim 5, It is characterized in that The organic ligand is selected from at least one of oxalic acid, malonic acid, succinic acid, suberic acid, 2,2'-biphenyldicarboxylic acid, fumaric acid, 1,2,4-butanetricarboxylic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-benzenetricarboxylic acid triethyl ester, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 3,3',5,5'-biphenyltetracarboxylic acid, 1,2,4-butanetricarboxylic acid, and 1,2,3-propanetricarboxylic acid.

7. A method for preparing the MOFs material according to any one of claims 1 to 6, It is characterized in that The following steps are involved: A metal salt solution and an organic ligand solution are added into a reaction kettle, and the temperature of the reaction kettle is controlled while stirring to obtain the MOFs material; the metal salt solution contains aluminum metal salt and calcium metal salt.

8. The method for preparing the MOFs material according to claim 7, It is characterized in that The molar concentration of the metal salt solution is 0.001-50 mol / L.

9. The method for preparing the MOFs material according to claim 7 or 8, It is characterized in that The molar concentration of the organic ligand solution is 0.01-30 mol / L.

10. The method for preparing the MOFs material according to claim 9, It is characterized in that The volume ratio of the metal salt solution to the organic ligand solution is (0.1-10):

1.

11. The method for preparing the MOFs material according to claim 7, It is characterized in that The aluminum metal salt is selected from at least one of aluminum nitrate, aluminum carbonate, aluminum bicarbonate, aluminum sulfate, aluminum chloride, aluminum oxychloride and hydrates of the above substances.

12. The method for preparing the MOFs material according to claim 7 or 11, It is characterized in that The calcium metal salt is selected from at least one of calcium nitrate, calcium carbonate, calcium bicarbonate, calcium sulfate, calcium chloride, calcium oxychloride and hydrates of the above substances.

13. The method for preparing the MOFs material according to any one of claim 12, It is characterized in that The solvents of the metal salt solution and the organic ligand solution are independently selected from at least one of water, methanol, ethanol, propanol, tetrahydrofuran, N,N-dimethylformamide and dimethyl sulfoxide.

14. The method for preparing the MOFs material according to claim 7, It is characterized in that The process of the temperature control treatment is: firstly heating to 30-50°C and keeping warm for 10-60min; then heating to 60-80°C and keeping warm for 5-60min; finally heating to 100-150°C and keeping warm for 5-60min.

15. The method for preparing the MOFs material according to claim 14, It is characterized in that The initial temperature of the reactor is 0-10°C.

16. The method for preparing the MOFs material according to claim 14 or 15, It is characterized in that The heating rate of the reactor is 1-15°C / min.

17. A water molecule adsorption material, It is characterized in that The MOFs material comprises any one of claims 1 to 6, or the MOFs material prepared by the preparation method of any one of claims 7 to 16.

18. An air treatment device, It is characterized in that The MOFs material comprises any one of claims 1 to 6, or the water molecule adsorption material comprises claim 17.

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