Metal-MOF material and preparation method and application thereof

Abstract

The invention belongs to the technical field of metal organic framework materials, and particularly relates to a metal-MOF material and a preparation method and application thereof. The metal-MOF material provided by the invention comprises a metal and an organic ligand, the metal is coordinated with four oxygen atoms provided by the three organic ligands; the metal comprises any one of cobalt, chromium and aluminum; the organic ligand comprises any one of 2, 5-dihydroxybiphenyl dicarboxylic acid, 3, 3 '-dihydroxy-4, 4'-biphenyl dicarboxylic acid and benzenetricarboxylic acid. According to the metal-MOF material and the preparation method thereof, coordination is carried out through a specific type of metal and a specific type of organic ligand, the structure of the metal-MOF material is not changed after the metal-MOF material is soaked in water for 7 days due to a special coordination mode between the metal and the organic ligand, 96% of initial load can still be achieved after 20 water adsorption and desorption cycles, the saturated water adsorption capacity can reach 0.98 g / g, and the metal-MOF material can be applied to water adsorption and desorption. The water stability, the water circulation stability and the saturated water adsorption capacity are good.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal organic framework materials, and in particular relates to a metal-MOF material and a preparation method and application thereof. Background Art

[0002] Atmospheric water usually exists in the form of steam and droplets, with a reserve of about 130 trillion liters. It is an important natural resource to alleviate the shortage of fresh water resources. At present, typical air water extraction methods mainly include fog capture, dew collection and adsorption air water extraction. However, the first two methods have certain limitations. For example, fog capture is heavily dependent on the local climate, generally only occurs in mountainous or coastal areas, and requires relative humidity (RH) to be less than 50%; while dew collection consumes a lot of energy, has high technical costs, and unstable water output. In comparison, adsorption air water extraction technology has certain advantages. On the one hand, the adsorbent used in air water extraction is not restricted by time and space, and can flexibly control pressure or temperature. On the other hand, it can use low-grade heat sources such as sunlight and industrial waste heat, which is economically sustainable. Therefore, adsorption air water extraction has received widespread attention in the field of water collection and purification.

[0003] The key to adsorption-based air water extraction technology lies in the selection of adsorbents. According to the different adsorption mechanisms between adsorbents and adsorbates, adsorbents can be divided into physical adsorbents and chemical adsorbents. Classic physical adsorbents include porous solid materials such as zeolite, activated carbon, silica gel, and organic polymers. Physical adsorbents generally have strong hydrophilicity, and there will be strong interactions between the adsorbent and the adsorbate (water vapor), which results in a high regeneration temperature (>160°C) required for desorption of the adsorbent, which consumes a lot of energy. Chemical adsorbents generally refer to hygroscopic salts, including CaCl 2 、LiCl 2 Although chemical adsorbents can solve the problem of high regeneration temperature during desorption of physical adsorbents, chemical adsorbents are prone to corrosion of equipment, adsorbent agglomeration and other problems, which will cause serious economic losses. Therefore, these traditional water-absorbing materials are not suitable for adsorbing a large amount of water molecules from dry air (RH < 40%). Metal organic frameworks (MOFs) are a unique class of highly crystalline porous materials, which are periodically connected by metal ions and organic linkers. Because they can quickly adsorb water vapor at low relative pressures and easily desorb water vapor at medium temperatures, they have developed into new water vapor adsorbents. However, existing MOF water adsorbents still have problems such as poor water stability, poor water cycle stability and low saturated water adsorption capacity.

[0004] Therefore, it is of great significance to provide a metal-MOF material with good water stability, water cycle stability and high saturated water adsorption capacity. 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.

[0006] Therefore, a first aspect of the present invention provides a metal-MOF material.

[0007] Specifically, a metal-MOF material includes a metal and an organic ligand;

[0008] The metal is coordinated with four oxygen atoms provided by the three organic ligands;

[0009] The metal includes any one of cobalt, chromium and aluminum;

[0010] The organic ligand includes any one of 2,5-dihydroxybiphenyl dicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid and trimesic acid.

[0011] Specifically, the metal-MOF material of the present invention has a specific type of metal and organic ligand, the metal is located in an asymmetric coordination environment, the metal and the four oxygen atoms provided by the three organic ligands are coordinated, that is, the binding position of each ligand and the metal (the position of the binding oxygen atom) is different, and this special coordination mode produces a high concentration of unsaturated metal sites and hydrophilic groups. Because of the symmetrical structure of the ligand, when a hydroxyl or carboxyl group is used to coordinate with the metal, there is another hydroxyl and carboxyl group exposed to the outside, so there are more hydrophilic groups, which is conducive to improving the affinity for water. In addition, the polycarboxyl structure of the organic ligand can provide relatively more coordination modes, and the connection of two benzene rings is conducive to the formation of long-chain MOF, and the rich hydroxyl structure is conducive to improving the affinity for water. Therefore, the specific type of metal ions and organic ligands and the special coordination mode between the two make the metal-MOF material have no change in structure after being soaked in water for 7 days, and can still reach 96% of the initial load after 20 water adsorption and desorption cycles, and the saturated water adsorption capacity can reach 0.98g / g, with good water stability, water cycle stability and high saturated water adsorption capacity.

[0012] According to some embodiments of the present invention, the trimesic acid includes any one of trimesic acid, trimellitic acid, and trimellitic acid.

[0013] According to some embodiments of the present invention, the molar ratio of the metal to the organic ligand is (0.9-11):1.

[0014] According to some embodiments of the present invention, the molar ratio of the metal to the organic ligand is (1-10):1.

[0015] According to some embodiments of the present invention, the molar ratio of the metal to the organic ligand is (2-5):1.

[0016] Specifically, the metal-MOF material of the present invention has a reasonable molar ratio between the metal and the organic ligand, which can avoid the problem of low saturated adsorption capacity of the material when the molar ratio between the two is too low. At the same time, the metal and the organic ligand have a more optimal coordination environment, which is beneficial to improve the affinity for water, thereby improving the water adsorption effect of the metal-MOF material, and has good water stability, water cycle stability and high saturated water adsorption capacity.

[0017] According to some embodiments of the present invention, the metal-MOF material has a porous rod-like structure.

[0018] According to some embodiments of the present invention, the width of the porous rod-like structure is 450 nm-1.1 μm.

[0019] According to some embodiments of the present invention, the width of the porous rod-like structure is 500 nm-1 μm.

[0020] Specifically, the metal-MOF material has a porous rod-like structure, and the presence of the porous feature is conducive to improving the adsorption of water and achieving the adsorption and storage of water.

[0021] According to some embodiments of the present invention, the pore diameter of the porous rod-like structure is 0.9 nm-110 nm.

[0022] According to some embodiments of the present invention, the pore size of the porous rod-like structure is 1 nm-100 nm.

[0023] According to some embodiments of the present invention, the pore size of the porous rod-like structure is 1 nm-50 nm.

[0024] According to some embodiments of the present invention, the pore size of the porous rod-like structure is 1 nm-2 nm.

[0025] Specifically, a reasonable pore size can avoid the adverse effects of too large pore size on the structural stability of the metal-MOF material, which in turn affects the performance of the metal-MOF material, such as reducing the water stability, water cycle stability and saturated water adsorption capacity of the metal-MOF material. In addition, the diameter of water molecules is about 0.4nm, and a reasonable pore size can also avoid the inability to achieve good adsorption of water molecules when the pore size is too small.

[0026] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-20000cm 2 / g.

[0027] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-10000cm2 / g.

[0028] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-8000cm 2 / g.

[0029] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-3000cm 2 / g.

[0030] Specifically, the metal-MOF material of the present invention has a large specific surface area, which provides a large space for water molecules to stay, which is conducive to achieving good adsorption of water, and further improves the water stability, water cycle stability and saturated water adsorption capacity of the metal-MOF material.

[0031] The second aspect of the present invention provides a method for preparing the metal-MOF material described in the first aspect of the present invention.

[0032] Specifically, the method for preparing the metal-MOF material comprises the following steps:

[0033] The metal salt and the organic ligand are mixed, reacted, and activated to obtain the metal-MOF material;

[0034] The metal salt includes any one of cobalt salt, chromium salt and aluminum salt;

[0035] When the metal salt includes a cobalt salt, the cobalt salt includes at least one of cobalt nitrate, cobalt chloride, and cobalt acetate; when the metal salt includes a chromium salt, the chromium salt includes at least one of chromium nitrate, chromium chloride, and chromium acetate; when the metal salt includes an aluminum salt, the aluminum salt includes at least one of aluminum nitrate, aluminum chloride, and aluminum acetate.

[0036] Specifically, the preparation process of the present invention is simple, and it adopts metal salt and organic ligand to mix directly, and is prepared by reaction, which is suitable for large-scale production and application, and has good economic benefits. In addition, the present invention adopts a specific type of metal salt to prepare metal-MOF material, the metal is located in an asymmetric coordination environment, and the metal atom and the four oxygen atoms provided by three organic ligands are coordinated, that is, the binding position of each ligand and metal (the position of binding oxygen atom) is different, and this special coordination mode produces a high concentration of unsaturated metal sites and hydrophilic groups, which is conducive to improving the affinity for water. Therefore, the specific type of metal and organic ligand and the special coordination mode between the two make the structure of the metal-MOF material not change after being soaked in water for 7 days, and can still reach 96% of the initial load after 20 water adsorption and desorption cycles, and the saturated water adsorption capacity can reach 0.98g / g, with good water stability, water cycle stability and high saturated water adsorption capacity.

[0037] According to some embodiments of the invention, the cobalt salt comprises cobalt nitrate.

[0038] According to some embodiments of the invention, the cobalt salt comprises cobalt nitrate hexahydrate.

[0039] According to some embodiments of the invention, the chromium salt comprises chromium nitrate.

[0040] According to some embodiments of the invention, the aluminum salt comprises aluminum nitrate.

[0041] According to some embodiments of the present invention, the organic ligand includes any one of 2,5-dihydroxybiphenyldicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyldicarboxylic acid, and trimellitic acid.

[0042] Specifically, the present invention can maximize the water stability, water cycle stability and high saturated water adsorption capacity of the metal-MOF material by optimizing the type of metal salt and reacting it with a specific type of organic ligand.

[0043] According to some embodiments of the present invention, the molar ratio of the metal salt to the organic ligand is (0.9-11):1.

[0044] According to some embodiments of the present invention, the molar ratio of the metal salt to the organic ligand is (1-10):1.

[0045] According to some embodiments of the present invention, the molar ratio of the metal salt to the organic ligand is (2-5):1.

[0046] Specifically, a certain ratio must be satisfied between the metal salt and the organic ligand. The present invention can avoid the problem of low saturated adsorption capacity of the material when the molar ratio between the two is too low by reasonably limiting the ratio of the metal salt and the organic ligand. At the same time, the metal and organic ligand in the metal-MOF material can have a better coordination environment, which is beneficial to improve the affinity for water, thereby improving the adsorption effect of the metal-MOF material on water, and achieving good water stability, water cycle stability and saturated water adsorption capacity.

[0047] According to some embodiments of the present invention, the metal salt is a metal salt solution; and the organic ligand is an organic ligand solution.

[0048] According to some embodiments of the present invention, the metal salt solution and the organic ligand solution are prepared using a solvent.

[0049] According to some embodiments of the present invention, the solvent comprises at least one of ethanol, N,N-dimethylformyl, and water.

[0050] According to some embodiments of the invention, the solvent comprises ethanol, N,N-dimethylformyl and water.

[0051] According to some embodiments of the present invention, the organic ligand and the solvent are first mixed, and then the metal salt is added and stirred to obtain a mixed solution.

[0052] Specifically, the metal salt and the organic ligand of the present invention are stirred and mixed in the form of a solution. Compared with direct mixing, the solution can make the metal salt and the organic ligand mix more fully, thereby facilitating the subsequent reaction process to proceed more fully.

[0053] According to some embodiments of the present invention, the reaction temperature is 70° C.-220° C., and the reaction time is 5.5 h-80 h.

[0054] According to some embodiments of the present invention, the reaction temperature is 80° C.-200° C., and the reaction time is 6 h-72 h.

[0055] According to some embodiments of the present invention, the reaction temperature is 100° C.-150° C., and the reaction time is 18 h-42 h.

[0056] Specifically, reasonable reaction temperature and reaction time can make the metal salt and organic ligand react fully, ensuring that a metal-MOF material with a good porous rod-like structure is obtained, thereby ensuring that the metal-MOF material has a good adsorption effect on water and achieves good water stability, water cycle stability and saturated water adsorption capacity.

[0057] According to some embodiments of the present invention, washing is performed after the reaction, and then the activation is performed.

[0058] According to some embodiments of the present invention, the washing is performed using a detergent.

[0059] According to some embodiments of the present invention, the detergent comprises at least one of N,N-dimethylformamide and methanol.

[0060] According to some embodiments of the present invention, N,N-dimethylformamide and methanol are used sequentially for washing.

[0061] Specifically, unreacted substances or residual solvents are retained in the porous structure. The occupation of the porous structure affects the adsorption of water by the porous characteristics, thereby reducing the adsorption performance of the metal-MOF material. The present invention can effectively remove unreacted substances and residual solvents by washing the product after the reaction, thereby ensuring that the porous structure can be completely and fully used for the adsorption of water, which is conducive to obtaining metal-MOF materials with excellent water adsorption performance.

[0062] According to some embodiments of the present invention, the activation is performed by vacuum drying.

[0063] According to some embodiments of the present invention, the vacuum drying is performed in a vacuum drying oven.

[0064] According to some embodiments of the present invention, the activation temperature is 70° C.-350° C., and the activation time is 3.5 h-52 h.

[0065] According to some embodiments of the present invention, the activation temperature is 80° C.-330° C., and the activation time is 4 h-48 h.

[0066] According to some embodiments of the present invention, the activation temperature is 100° C.-150° C., and the activation time is 12 h-24 h.

[0067] Specifically, by activating the washed product in a vacuum drying manner, the unreacted substances and the residual solvent can be further removed to obtain a metal-MOF material with a porous structure and a large specific surface area, so that the metal-MOF material has excellent water adsorption performance, and improves the saturated water adsorption capacity, water stability and water cycle stability. In addition, by limiting the reasonable activation temperature and activation time, the activation process can be carried out smoothly and fully, so that the activated metal-MOF material has good water adsorption performance. At the same time, by limiting the reasonable temperature and time, while ensuring the performance of the metal-MOF material, unnecessary energy consumption can be avoided.

[0068] A third aspect of the present invention provides an adsorbent.

[0069] Specifically, the adsorbent includes the metal-MOF material described in the first aspect of the present invention.

[0070] According to some embodiments of the present invention, the adsorbent includes any one of a water adsorbent, a gas adsorbent, and a heavy metal adsorbent.

[0071] According to some embodiments of the invention, the gas sorbent comprises a carbon dioxide sorbent.

[0072] Specifically, the metal-MOF material of the present invention has a porous structure and a large specific surface area. When it is applied to an adsorbent, it can achieve effective adsorption of water, gas and heavy metals, especially when used as a water adsorbent, it has a good adsorption effect on water, and the saturated water adsorption capacity can reach 0.98g / g. In addition, after being immersed in water for 7 days, its structure did not change, and after 20 cycles of water adsorption and desorption, it could still reach 96% of the initial load, with good water stability and water cycle stability, and can well meet the needs of adsorption-type air water extraction.

[0073] A fourth aspect of the present invention provides an air purifier or a dehumidifier.

[0074] Specifically, the air purifier or desiccant includes the adsorbent described in the third aspect of the present invention.

[0075] Specifically, the adsorbent of the present invention has a good adsorption effect on water, gas and heavy metal ions. When it is applied to an air purifier, it can purify the air and remove pollutants, which is beneficial to health; when it is applied to a dehumidifier, it can reduce the humidity in the environment and improve the comfort of the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 This is the coordination environment diagram of the Co-MOF-P material prepared in Example 1 of the present invention;

[0077] Figure 2 This is a scanning electron microscope image of the Co-MOF-P material prepared in Example 1 of the present invention;

[0078] Figure 3 N is the Co-MOF-P material prepared in Example 1 of the present invention 2 Adsorption-desorption test result diagram;

[0079] Figure 4 The contact angle test results of the materials prepared in Example 1 and Comparative Example 1 of the present invention are shown in FIG.

[0080] Figure 5 The infrared spectra of the materials prepared in Example 1 and Comparative Example 1 of the present invention;

[0081] Figure 6This is a graph showing the water stability test results of the Co-MOF-P material prepared in Example 1 of the present invention;

[0082] Figure 7 This is a graph showing the water adsorption cycle performance test results of the Co-MOF-P material prepared in Example 1 of the present invention;

[0083] Figure 8 This is a graph showing the water adsorption performance test results of the materials prepared in Example 1 of the present invention and Comparative Example 1;

[0084] Fig. 9 This is a graph showing the water adsorption performance test results of the materials prepared in Examples 1-3 of the present invention;

[0085] Fig.10 This is a graph showing the water adsorption performance test results of the materials prepared in Example 1 and Examples 4-5 of the present invention;

[0086] Fig.11 This is a graph showing the water adsorption performance test results of the materials prepared in Example 1 and Examples 6-7 of the present invention;

[0087] Fig.12 This is a graph showing the test results of the water adsorption performance of the materials prepared in Examples 1-3 and Comparative Examples 2-7 of the present invention. DETAILED DESCRIPTION

[0088] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0089] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0090] A first aspect of an embodiment of the present invention provides a metal-MOF material, comprising a metal and an organic ligand;

[0091] The metal and the four oxygen atoms provided by the three organic ligands coordinate;

[0092] The metal includes any one of cobalt, chromium and aluminum;

[0093] The organic ligand includes any one of 2,5-dihydroxybiphenyldicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyldicarboxylic acid, and trimellitic acid.

[0094] The metal-MOF material of the embodiment of the present invention has a specific type of metal and organic ligand, the metal atom is located in an asymmetric coordination environment, and the metal atom is coordinated with four oxygen atoms provided by three organic ligands, that is, the binding position of each ligand and the metal (the position of the binding oxygen atom) is different. This special coordination mode produces a high concentration of unsaturated metal sites and hydrophilic groups. Because of the symmetrical structure of the ligand, when a hydroxyl or carboxyl group is used to coordinate with the metal, another hydroxyl and carboxyl group are exposed to the outside, that is, there are more hydrophilic groups, which is conducive to improving the affinity for water. In addition, the specific type of organic ligand of the embodiment of the present invention has a multi-carboxyl structure, which can provide relatively more coordination modes. The connection of two benzene rings is conducive to the formation of a long-chain MOF, and the rich hydroxyl structure is more conducive to improving the affinity for water. Therefore, the specific types of metals and organic ligands and the special coordination mode between the two make the structure of the metal-MOF material unchanged after being immersed in water for 7 days. After 20 cycles of water adsorption and desorption, it can still reach 96% of the initial load, and the saturated water adsorption capacity can reach 0.98g / g, with good water stability, water cycle stability and saturated water adsorption capacity.

[0095] According to some embodiments of the invention, the metal includes cobalt.

[0096] According to some embodiments of the present invention, the organic ligand comprises 2,5-dihydroxybiphenyldicarboxylic acid.

[0097] In the embodiment of the present invention, the 2,5-dihydroxybiphenyl dicarboxylic acid organic ligand has a multi-carboxyl structure. The two benzene rings are connected to form a long-chain MOF. The rich hydroxyl structure is beneficial to improving the affinity for water. Its coordination with metal cobalt can obtain a high concentration of unsaturated metal sites and hydrophilic groups, thereby improving the affinity for water.

[0098] According to some embodiments of the present invention, trimesic acid includes any one of trimesic acid, pyromellitic acid, and trimellitic acid.

[0099] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is (0.9-11):1.

[0100] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is (1-10):1.

[0101] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is (2-5):1.

[0102] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is 3:1.

[0103] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is 4:1.

[0104] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is 5:1.

[0105] The embodiments of the present invention can avoid the problem of low saturated adsorption capacity of the material when the molar ratio between the metal and the organic ligand is too low by reasonably limiting the molar ratio between the two. At the same time, a better coordination environment is provided between the metal and the organic ligand, with more high-concentration unsaturated metal sites and hydrophilic groups, which is beneficial to improving the affinity for water, thereby improving the adsorption effect of the metal-MOF material on water, and having good water stability, water cycle stability and saturated water adsorption capacity.

[0106] According to some embodiments of the present invention, the metal-MOF material has a porous rod-like structure.

[0107] According to some embodiments of the present invention, the width of the porous rod-like structure is 450 nm-1.1 μm.

[0108] According to some embodiments of the present invention, the width of the porous rod-like structure is 500 nm-1 μm.

[0109] The metal-MOF material of the embodiment of the present invention has a porous rod-like structure, and the presence of the porous feature is conducive to improving the adsorption of water, thereby achieving the adsorption and storage of water.

[0110] According to some embodiments of the present invention, the pore size of the metal-MOF material is 0.9 nm-110 nm.

[0111] According to some embodiments of the present invention, the pore size of the metal-MOF material is 1 nm-100 nm.

[0112] According to some embodiments of the present invention, the pore size of the metal-MOF material is 1 nm-50 nm.

[0113] According to some embodiments of the present invention, the pore size of the metal-MOF material is 1 nm-2 nm.

[0114] The metal-MOF material of the embodiment of the present invention has a reasonable pore size, which can avoid the adverse effect of the metal-MOF material's pore size being too large on the structural stability of the metal-MOF material, thereby affecting the performance of the metal-MOF material, such as reducing the water stability, water cycle stability and saturated water adsorption capacity of the metal-MOF material. In addition, the diameter of water molecules is about 0.4nm, and a reasonable pore size can also avoid the inability to achieve good adsorption of water molecules when the pore size is too small.

[0115] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-20000cm 2 / g.

[0116] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-10000cm 2 / g.

[0117] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-8000cm 2 / g.

[0118] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-3000cm 2 / g.

[0119] According to some embodiments of the present invention, the specific surface area of ​​the metal-MOF material is 1349 cm 2 / g.

[0120] The metal-MOF material of the embodiment of the present invention has a large specific surface area. The larger the specific surface area, the larger the space for water molecules to stay, which is more conducive to achieving good adsorption of water, and thus can also improve the water stability, water cycle stability and saturated water adsorption capacity of the metal-MOF material.

[0121] The second aspect of the present invention provides a method for preparing the metal-MOF material of the first aspect of the present invention, comprising the following steps:

[0122] The metal salt and the organic ligand are mixed, reacted, and activated to obtain a metal-MOF material;

[0123] The metal salt includes any one of cobalt salt, chromium salt and aluminum salt;

[0124] When the metal salt includes a cobalt salt, the cobalt salt includes at least one of cobalt nitrate, cobalt chloride, and cobalt acetate; when the metal salt includes a chromium salt, the chromium salt includes at least one of chromium nitrate, chromium chloride, and chromium acetate; when the metal salt includes an aluminum salt, the aluminum salt includes at least one of aluminum nitrate, aluminum chloride, and aluminum acetate.

[0125] The embodiment of the present invention directly mixes the metal salt and the organic ligand, and reacts to prepare the metal-MOF material. The preparation process is simple, easy to operate, suitable for large-scale production and application, and has good economic benefits. In addition, the embodiment of the present invention uses a specific type of metal salt to prepare the metal-MOF material. The metal is located in an asymmetric coordination environment, and the metal atom and the four oxygen atoms provided by the three organic ligands are coordinated, that is, the binding position of each ligand and the metal (the position of the binding oxygen atom) is different. This special coordination mode produces a high concentration of unsaturated metal sites and hydrophilic groups, which is conducive to improving the affinity for water. Therefore, the specific type of metal and organic ligand and the special coordination mode between the two make the metal-MOF material have no change in structure after being soaked in water for 7 days, and can still reach 96% of the initial load after 20 water adsorption and desorption cycles, and the saturated water adsorption capacity can reach 0.98g / g, with good water stability, water cycle stability and high saturated water adsorption capacity.

[0126] According to some embodiments of the invention, the cobalt salt includes cobalt nitrate.

[0127] According to some embodiments of the invention, the cobalt salt includes cobalt nitrate hexahydrate.

[0128] According to some embodiments of the invention, the chromium salt comprises chromium nitrate.

[0129] According to some embodiments of the invention, the aluminum salt comprises aluminum nitrate.

[0130] According to some embodiments of the present invention, the organic ligand includes any one of 2,5-dihydroxybiphenyldicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyldicarboxylic acid, and trimellitic acid.

[0131] According to some embodiments of the present invention, the organic ligand comprises 2,5-dihydroxybiphenyldicarboxylic acid.

[0132] The embodiments of the present invention can maximize the water stability, water cycle stability and high saturated water adsorption capacity of the metal-MOF material by optimizing the type of metal salt and reacting it with a specific type of organic ligand.

[0133] According to some embodiments of the present invention, the molar ratio of the metal salt to the organic ligand is (0.9-11):1.

[0134] According to some embodiments of the present invention, the molar ratio of the metal salt to the organic ligand is (1-10):1.

[0135] According to some embodiments of the present invention, the molar ratio of the metal salt to the organic ligand is (2-5):1.

[0136] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is 3:1.

[0137] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is 4:1.

[0138] According to some embodiments of the present invention, the molar ratio of metal to organic ligand is 5:1.

[0139] In the embodiment of the present invention, when preparing the metal-MOF material, the metal salt and the organic ligand have a reasonable molar ratio, which can avoid the problem of low saturated adsorption capacity of the material when the molar ratio between the two is too low. At the same time, a better coordination environment is provided between the metal and the organic ligand, resulting in a high concentration of unsaturated metal sites and hydrophilic groups, which is beneficial to improve the affinity for water, thereby improving the adsorption effect of the metal-MOF material on water, so that the metal-MOF material has good water stability, water cycle stability and saturated water adsorption capacity.

[0140] According to some embodiments of the present invention, the metal salt is a metal salt solution; and the organic ligand is an organic ligand solution.

[0141] According to some embodiments of the present invention, a solvent is used to prepare the metal salt solution and the organic ligand solution.

[0142] According to some embodiments of the present invention, the solvent includes at least one of ethanol, N,N-dimethylformyl, and water.

[0143] According to some embodiments of the present invention, the solvent includes anhydrous 7-ethanol, N,N-dimethylformamide and water.

[0144] According to some embodiments of the present invention, the organic ligand and the solvent are first mixed, and then the metal salt is added and stirred to obtain a mixed solution.

[0145] In the embodiment of the present invention, the metal salt and the organic ligand are stirred and mixed in the form of a solution. Compared with direct mixing, the solution can make the metal salt and the organic ligand mix more fully, which is more conducive to the subsequent reaction process.

[0146] According to some embodiments of the present invention, the reaction temperature is 70° C.-220° C., and the reaction time is 5.5 h-80 h.

[0147] According to some embodiments of the present invention, the reaction temperature is 80° C.-200° C., and the reaction time is 6 h-72 h.

[0148] According to some embodiments of the present invention, the reaction temperature is 100° C.-150° C., and the reaction time is 18 h-42 h.

[0149] According to some embodiments of the present invention, the reaction temperature is 100° C. and the reaction time is 30 h.

[0150] According to some embodiments of the present invention, the reaction temperature is 120° C. and the reaction time is 30 h.

[0151] According to some embodiments of the present invention, the reaction temperature is 150° C. and the reaction time is 30 h.

[0152] According to some embodiments of the present invention, the reaction temperature is 100° C. and the reaction time is 18 h.

[0153] According to some embodiments of the present invention, the reaction temperature is 100° C. and the reaction time is 42 h.

[0154] The embodiments of the present invention can make the metal salt and the organic ligand react fully by adopting a reasonable reaction temperature and reaction time, thereby ensuring that a metal-MOF material with a good porous rod-like structure is obtained, thereby ensuring that the metal-MOF material has a good adsorption effect on water and achieves good water stability, water cycle stability and saturated water adsorption capacity.

[0155] According to some embodiments of the present invention, washing is performed first after the reaction, and then activation is performed.

[0156] According to some embodiments of the present invention, washing is performed using a detergent.

[0157] According to some embodiments of the present invention, the detergent includes at least one of N,N-dimethylformamide and methanol.

[0158] According to some embodiments of the present invention, N,N-dimethylformamide (DMF) and methanol are used sequentially for washing.

[0159] The embodiment of the present invention can well remove the unreacted substances and residual solvent by washing the product after the reaction, ensuring that the porous structure can be completely and fully used for water adsorption, which is conducive to obtaining metal-MOF materials with excellent water adsorption performance. Because the unreacted substances or residual solvents are retained in the porous structure, the occupation of the porous structure will affect the adsorption of water by the porous characteristics, thereby reducing the water adsorption performance of the metal-MOF material.

[0160] According to some embodiments of the present invention, activation is performed by vacuum drying.

[0161] According to some embodiments of the present invention, vacuum drying is performed in a vacuum drying oven.

[0162] According to some embodiments of the present invention, the activation temperature is 70° C.-350° C., and the activation time is 3.5 h-52 h.

[0163] According to some embodiments of the present invention, the activation temperature is 80° C.-330° C., and the activation time is 4 h-48 h.

[0164] According to some embodiments of the present invention, the activation temperature is 100° C.-150° C., and the activation time is 12 h-24 h.

[0165] According to some embodiments of the present invention, the activation temperature is 120° C., and the activation time is 12 h.

[0166] The embodiment of the present invention activates the washed product by vacuum drying, further removes the unreacted substances and the residual solvent, and obtains a metal-MOF material with a porous structure and a large specific surface area, so that the metal-MOF material has excellent water adsorption performance, improves the saturated water adsorption capacity, water stability and water cycle stability. In addition, by limiting reasonable activation temperature and activation time, the activation process can be carried out smoothly and fully, so that the activated metal-MOF material has good water adsorption performance. At the same time, by limiting reasonable temperature and time, while ensuring the performance of the metal-MOF material, unnecessary energy consumption can be avoided.

[0167] The third aspect of the present invention provides an adsorbent, comprising the metal-MOF material of the first aspect of the present invention.

[0168] According to some embodiments of the present invention, the adsorbent includes any one of a water adsorbent, a gas adsorbent, and a heavy metal ion adsorbent.

[0169] According to some embodiments of the present invention, the gas sorbent includes a carbon dioxide sorbent.

[0170] The metal-MOF material of the embodiment of the present invention has a porous structure, a small pore size and a large specific surface area. When it is applied to an adsorbent, it can achieve effective adsorption of water, gas and heavy metal ions, especially when used as a water adsorbent, it has a good adsorption effect on water, and the saturated water adsorption capacity can reach 0.98g / g. In addition, after being immersed in water for 7 days, its structure did not change, and after 20 cycles of water adsorption and desorption, it could still reach 96% of the initial load, with good water stability and water cycle stability, and can well meet the needs of adsorption-type air water extraction.

[0171] The fourth aspect of the present invention provides an air purifier or a desiccant, comprising the adsorbent according to the third aspect of the present invention.

[0172] The adsorbent of the embodiment of the present invention can effectively adsorb water, gas and heavy metal ions. When it is applied to an air purifier, it can purify the air and remove pollutants, which is beneficial to health; when it is applied to a dehumidifier, it can reduce the humidity in the environment and improve the comfort of the human body.

[0173] Example 1

[0174] A method for preparing a Co-MOF material comprises the following steps:

[0175] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 2.181 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 100 ° C for 30 h. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. Then, it was placed in a vacuum drying oven and vacuum dried at 120 ° C for 12 h to obtain the product Co-MOF material, which was recorded as Co-MOF-P (or Co-MOF-31).

[0176] The coordination environment diagram of the Co-MOF-P material prepared in Example 1 is as follows Figure 1 As shown. Figure 1 It can be seen that Co is located in an asymmetric coordination environment and is coordinated with the four oxygen atoms of the three organic ligands 2,5-dihydroxybiphenyl dicarboxylic acid. Moreover, the binding position of each 2,5-dihydroxybiphenyl dicarboxylic acid organic ligand and the Co atom is different, that is, the coordination position (the position of the binding oxygen atom) is different.

[0177] Example 2

[0178] A method for preparing a Co-MOF material comprises the following steps:

[0179] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 2.908 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 100 ° C for 30 h. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. Then, it was placed in a vacuum drying oven and vacuum dried at 120 ° C for 12 h to obtain the product Co-MOF material, which was recorded as Co-MOF-4:1 (or recorded as Co-MOF-41).

[0180] Example 3

[0181] A method for preparing a Co-MOF material comprises the following steps:

[0182] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 3.635 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 100 ° C for 30 h. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. Then, it was placed in a vacuum drying oven and vacuum dried at 120 ° C for 12 h to obtain the product Co-MOF material, which was recorded as Co-MOF-5:1 (or recorded as Co-MOF-51).

[0183] Example 4

[0184] A method for preparing a Co-MOF material comprises the following steps:

[0185] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 2.181 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 120°C for 30 h. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. Then, it was placed in a vacuum drying oven and vacuum dried at 120°C for 12 h to obtain the product Co-MOF material, which was recorded as Co-MOF-120°C.

[0186] Example 5

[0187] A method for preparing a Co-MOF material comprises the following steps:

[0188] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 2.181 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 150°C for 30 hours. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. It was placed in a vacuum drying oven and vacuum dried at 120°C for 12 hours to obtain the product Co-MOF material, recorded as Co-MOF-150°C.

[0189] Example 6

[0190] A method for preparing a Co-MOF material comprises the following steps:

[0191] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 2.181 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 100°C for 18 h. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. Then, it was placed in a vacuum drying oven and vacuum dried at 120°C for 12 h to obtain the product Co-MOF material, which was recorded as Co-MOF-18h.

[0192] Example 7

[0193] A method for preparing a Co-MOF material comprises the following steps:

[0194] 0.727 mmol of 2,5-dihydroxybiphenyldicarboxylic acid powder was dissolved in a mixed solvent of 20 mL of deionized water, 20 mL of DMF and 20 mL of anhydrous ethanol, and stirred until the powder was completely dissolved. Then, 2.181 mmol of cobalt nitrate hexahydrate was added and stirred until it was completely dissolved to obtain a mixed solution. The mixed solution was transferred to a 100 mL reactor and reacted at 100°C for 42 hours. After cooling to room temperature, it was washed and washed with DMF and methanol for 3 times respectively. Then, it was placed in a vacuum drying oven and vacuum dried at 120°C for 12 hours to obtain the product Co-MOF material, which was recorded as Co-MOF-42h.

[0195] Comparative Example 1

[0196] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses an equal amount of 4,4-biphenyldicarboxylic acid to replace the 2,5-dihydroxybiphenyldicarboxylic acid in Example 1, and the rest is the same as Example 1, and is recorded as Co-MOF-44.

[0197] Comparative Example 2

[0198] The difference between Comparative Example 2 and Example 1 is that the metal salt in Comparative Example 2 is an iron salt, and the preparation method of the Fe-MOF material in Comparative Example 2 comprises the following steps:

[0199] 2,5-Dihydroxybiphenyldicarboxylic acid (0.69 g, 2.50 mmol) was mixed with 30 mL of a mixed solvent of DMF (27 mL) and NaOH (0.4 M, 3 mL) in a Teflon liner and stirred until completely dissolved. Then, FeCl 3 6H 2O (0.68 g, 2.50 mmol), stirred for 20 min to obtain a mixed solution, which was placed in a 100 mL Teflon autoclave and reacted at 100 ° C for 24 h. After cooling, it was washed with deionized water and anhydrous ethanol for 3 times respectively. Finally, the sample was transferred to a vacuum drying oven and dried at 60 ° C for 12 h to obtain a Fe-MOF material, which was recorded as Fe-MOF-11.

[0200] Comparative Example 3

[0201] The only difference between Comparative Example 3 and Comparative Example 2 is that FeCl 3 6H 2 The amount of O added was adjusted to 1.25 mmol, and the other procedures were the same as those in Comparative Example 2 to obtain a Fe-MOF material, which was recorded as Fe-MOF-12.

[0202] Comparative Example 4

[0203] The only difference between Comparative Example 4 and Comparative Example 2 is that FeCl 3 6H 2 The addition amount of O was adjusted to 5 mmol, and the other conditions were the same as those in Comparative Example 2. The obtained Fe-MOF material was recorded as Fe-MOF-21.

[0204] Comparative Example 5

[0205] The difference between Comparative Example 5 and Example 1 is that the metal salt in Comparative Example 5 is a zirconium salt, and the preparation method of the Zr-MOF material in Comparative Example 5 comprises the following steps:

[0206] 2,5-dihydroxybiphenyl dicarboxylic acid (0.14 g, 0.52 mmol), benzoic acid (1.83 g, 1.50 mmol), ZrCl 4 (0.12 g, 0.52 mmol) was mixed and dissolved with 20 mL of DMF and 0.67 mL of hydrochloric acid, and stirred until transparent to obtain a mixture. The mixture was placed in a 100 mL Teflon-lined autoclave and heated at 120 ° C for 24 h. The cooled sample was washed with DMF and methanol for 3 times, respectively. Finally, the sample was transferred to a vacuum drying oven and vacuum dried at 100 ° C for 12 h to obtain a Zr-MOF material, recorded as Zr-MOF-11.

[0207] Comparative Example 6

[0208] The only difference between Comparative Example 6 and Comparative Example 5 is that ZrCl 4 The addition amount was adjusted to 0.26 mmol, and the other conditions were the same as those in Comparative Example 5 to obtain a Zr-MOF material, which was recorded as Zr-MOF-12.

[0209] Comparative Example 7

[0210] The only difference between Comparative Example 7 and Comparative Example 5 is that ZrCl 4 The addition amount was adjusted to 1.04 mmol, and the other conditions were the same as those in Comparative Example 5 to obtain a Zr-MOF material, which was recorded as Zr-MOF-21.

[0211] Performance Testing

[0212] 1. Scanning electron microscopy observation

[0213] The Co-MOF-P material prepared in Example 1 was observed by scanning electron microscopy. Figure 2 shown.

[0214] Depend on Figure 2 It can be seen that the Co-MOF-P material prepared in Example 1 has a porous rod-like structure with uniform morphology, and the size of the porous rod-like structure in the width direction is 500nm-1μm.

[0215] 2.N 2 Adsorption and desorption test

[0216] The Co-MOF-P material prepared in Example 1 was subjected to N 2 Adsorption-desorption test, the results are as follows Figure 3 As shown, Figure 3 (a) is the N of the Co-MOF-P material prepared in Example 1 2 Adsorption-desorption curve diagram, Figure 3 (b) is the pore size distribution diagram;

[0217] Figure 3 The horizontal axis of (a) is Relative Pressure (P / P 0 ) represents relative pressure, and the vertical axis is Quantity absorbed (cm 3 / g) represents the adsorption amount, Co-MOF-P-Ads and Co-MOF-P-Des represent the adsorption and desorption curves of Co-MOF-P materials, respectively; Figure 3 In (b), the abscissa dp (nm) represents the pore diameter, and the ordinate dVp / dlogdp represents the pore area.

[0218] Depend on Figure 3 It can be seen that the N of the Co-MOF-P material prepared in Example 1 2 The adsorption-desorption curves conform to the type I isotherm. The pore structure is mainly micropores. The existence of hysteresis loops indicates that capillary condensation occurs, and multilayer adsorption can occur. The specific surface area reaches 1349m 2 / g, which is one of the reasons why Co-MOF-P material has good water adsorption performance.

[0219] 3. Contact angle test

[0220] The contact angle test was performed on the Co-MOF-P prepared in Example 1 and the Co-MOF-44 prepared in Comparative Example 1. The test results are as follows: Figure 4 As shown, Figure 4 (a) and (b) are the contact angle test results of Co-MOF-P and Co-MOF-44, respectively.

[0221] like Figure 4 It can be seen that the maximum contact angle of the Co-MOF-P material of Example 1 is 47.5°, while the maximum contact angle of the Co-MOF-44 material of Comparative Example 1 is 54.4°, indicating that the Co-MOF-P of Example 1 of the present invention has higher hydrophilicity and thus has better water adsorption performance.

[0222] 4. Infrared spectrum test

[0223] The Co-MOF-31 prepared in Example 1 and the Co-MOF-44 prepared in Comparative Example 1 were subjected to infrared spectroscopy test. The infrared spectra are shown in FIG. Figure 5 shown.

[0224] Depend on Figure 5 It can be seen that the Co-MOF-31 material of Example 1 has a peak at a wave number of about 3500, indicating that there are hydroxyl groups in the Co-MOF-31 material, while the Co-MOF-44 material of Comparative Example 1 has no peak at a wave number of about 3500, and the curve is basically flat, indicating that the Co-MOF-44 material has no hydroxyl groups, that is, the Co-MOF-31 of Example 1 has more hydroxyl groups than the Co-MOF-44 of Comparative Example 1. Therefore, it can be inferred that the Co-MOF-31 material of Example 1 of the present invention has good hydrophilicity, and the reason is that the interaction between water molecules and the hydroxyl groups present in the pores of the porous rod-like structure can improve the water adsorption.

[0225] 5. Water stability test

[0226] The water stability performance of the Co-MOF-P material prepared in Example 1 was tested by X-ray diffraction, and the specific testing method is as follows:

[0227] 1 g of the Co-MOF-P material prepared in Example 1 was taken, and an X-ray diffraction analysis was performed on the Co-MOF-P material before immersion in water to obtain an X-ray diffraction spectrum before immersion in water.

[0228] Take 1 g of the Co-MOF-P material prepared in Example 1 and soak it in water for 7 days. After 7 days, the sample is centrifuged, taken out and placed in an oven at 100°C for drying. The dried sample is ground into powder, the powder is placed in a groove of a glass sheet, and the sample is compacted with a press. The Co-MOF-P material after immersion in water is subjected to X-ray diffraction analysis to obtain an X-ray diffraction pattern after immersion in water.

[0229] Test conditions: Cu-Ka was used as the light source, the scanning speed was 5° / min, and the scanning range was 5-80°.

[0230] The structure of the Co-MOF-P material before and after immersion in water was characterized by X-ray diffraction, and whether the Co-MOF-P material had good water stability was indicated by whether the structural characteristics before and after immersion in water changed. If the structure changed, it indicated that its water stability was poor; if the structure did not change, it indicated that it had good water stability.

[0231] The water stability performance of the Co-MOF-P material prepared in Example 1 is as follows Figure 6 As shown, the abscissa 2θ represents the diffraction angle, the ordinate Intensity represents the diffraction intensity, In water for 7 days represents the sample immersed in water for 7 days, and As synthesized represents the sample not immersed in water after synthesis.

[0232] Depend on Figure 6 It can be seen that the X-ray diffraction pattern of the sample after 7 days of immersion is consistent with the X-ray diffraction pattern of the sample before immersion, indicating that the structure of the Co-MOF-P material prepared in Example 1 of the present invention has not changed after 7 days of immersion, further indicating that the Co-MOF-P material prepared in Example 1 has good water stability. Figure 6 It can also be seen that the Co-MOF-P material has a higher degree of crystallinity, so its adsorption performance is better, which is one of the reasons why the Co-MOF-P material has good water adsorption performance.

[0233] 6. Water adsorption cycle performance test

[0234] The Co-MOF-P material prepared in Example 1 was subjected to a water adsorption cycle performance test. The water adsorption cycle performance results are shown in FIG. Figure 7 As shown, the horizontal axis Cycles represents the number of cycles, and the vertical axis Adsorption capacity (gg -1 ) represents the adsorption amount.

[0235] The test method for water adsorption cycle performance is:

[0236] Take 2g of the sample prepared in Example 1 and dried after activation, place it in a water tank at room temperature 25°C and humidity 100% RH to adsorb water vapor, place it for 8 hours, take it out and weigh the sample mass, put it in an oven at a temperature of 100°C for 8 hours to desorb water vapor, then take it out and weigh the sample mass, and put it back into the water tank, repeat this cycle for 20 times, finally take the sample out of the water tank and weigh the sample mass. The final sample mass is 3.92g, proving that the load can still reach 96% of the initial load after 20 adsorption and desorption cycles.

[0237] Depend on Figure 7 It can be seen that after 20 water adsorption-desorption cycles, the saturated water adsorption capacity of the Co-MOF-P material prepared in Example 1 can still reach an average of about 0.96 g / g, which proves that the material has good water cycle stability.

[0238] 7. Water adsorption performance test

[0239] (1) The water adsorption performance of the Co-MOF-P material of Example 1 and the Co-MOF-44 material of Comparative Example 1 was tested. The specific test method is as follows:

[0240] Take 0.5 g of the MOFs sample dried after activation in Example 1 and Comparative Example 1, vacuum activate it at 120° C. for 24 h, set the water vapor adsorption and desorption program, set the true mass of the sample according to the mass difference of the sample before and after pretreatment, and test it in the range of relative pressure (P / P0) of 0-1. The test is carried out at room temperature.

[0241] The water adsorption performance test results of the Co-MOF-P material of Example 1 and the Co-MOF-44 material of Comparative Example 1 are as follows: Figure 8 As shown, the horizontal axis P / P0 represents the relative pressure, and the vertical axis Vα / cm 3 (STP) -1 represents the pore volume, Co-MOF-P-Ads and Co-MOF-P-Des represent the adsorption and desorption curves of Co-MOF-P material, respectively, and Co-MOF-44-Ads and Co-MOF-44-Des represent the adsorption and desorption curves of Co-MOF-44 material, respectively.

[0242] Depend on Figure 8It can be seen that the water adsorption capacity of the Co-MOF-P adsorbent of Example 1 of the present invention can reach 0.78 g / g when the relative pressure is about 0.3, and the water adsorption capacity can reach 0.98 g / g when the relative pressure is 1, and the saturated adsorption capacity of the Co-MOF-P of Example 1 of the present invention is higher than that of the Co-MOF-44 of Comparative Example 1, indicating that the water adsorption performance of the Co-MOF-P material of Example 1 of the present invention is significantly better than that of the Co-MOF-44 of Comparative Example 1. At the same time, Co-MOF-31 has good water adsorption performance at a lower relative humidity, which is more conducive to use under low humidity conditions, indicating that the use of a specific type of ligand in the present invention is conducive to improving the water adsorption performance of the Co-MOF material.

[0243] (2) The water adsorption performance of the materials obtained in Example 1, Example 2 and Example 3 was tested. The specific testing method was the same as the testing method in the above section (1).

[0244] The water adsorption performance test results of the materials prepared in Example 1, Example 2 and Example 3 are as follows: Fig. 9 As shown, the horizontal axis P / P0 represents the relative pressure, and the vertical axis Vα / cm 3 (STP) -1 represents the pore volume, Co-MOF-P-Ads and Co-MOF-P-Des represent the adsorption and desorption curves of Co-MOF-P material, Co-MOF-4:1-Ads and Co-MOF-4:1-Des represent the adsorption and desorption curves of Co-MOF-4:1 material, Co-MOF-5:1-Ads and Co-MOF-5:1-Des represent the adsorption and desorption curves of Co-MOF-5:1 material, respectively.

[0245] Depend on Fig. 9 It can be seen that when the molar ratio of metal salt to organic ligand is 3:1, the prepared Co-MOF material has better adsorption performance for water vapor than the Co-MOF materials with molar ratios of 4:1 and 5:1, that is, the water adsorption performance of Co-MOF-P in Example 1 is better than the water adsorption performance of Co-MOF-4:1 and Co-MOF-5:1 in Examples 2 and 3.

[0246] (3) The water adsorption performance of the materials prepared in Example 1, Example 4 and Example 5 was tested, and the specific test method was the same as the test method in the above section (1).

[0247] The water adsorption performance test results of the materials prepared in Example 1, Example 4 and Example 5 are as follows: Fig.10 As shown, the horizontal axis P / P0 represents the relative pressure, and the vertical axis Vα / cm 3 (STP) -1represents the pore volume, Co-MOF-P-Ads and Co-MOF-P-Des represent the adsorption and desorption curves of Co-MOF-P material, Co-MOF-120℃-Ads and Co-MOF-120℃-Des represent the adsorption and desorption curves of Co-MOF-120℃ material, Co-MOF-150℃-Ads and Co-MOF-150℃-Des represent the adsorption and desorption curves of Co-MOF-150℃ material, respectively.

[0248] Depend on Fig.10 It can be seen that the adsorption performance of Co-MOF prepared at a reaction temperature of 100°C for water vapor is better than that of Co-MOF prepared at reaction temperatures of 120°C and 150°C for water vapor.

[0249] (4) The water adsorption performance of the materials prepared in Example 1, Example 6 and Example 7 was tested, and the specific testing method was the same as the testing method in the above section (1).

[0250] The water adsorption performance test results of the materials prepared in Example 1, Example 6 and Example 7 are as follows: Fig.11 As shown, the horizontal axis P / P0 represents the relative pressure, and the vertical axis Vα / cm 3 (STP) -1 represents the pore volume, Co-MOF-P-Ads and Co-MOF-P-Des represent the adsorption and desorption curves of Co-MOF-P material, Co-MOF-18h-Ads and Co-MOF-18h-Des represent the adsorption and desorption curves of Co-MOF-18h material, Co-MOF-42h-Ads and Co-MOF-42h-Des represent the adsorption and desorption curves of Co-MOF-42h material, respectively.

[0251] Depend on Fig.11 It can be seen that the water vapor adsorption performance of Co-MOF prepared with a reaction time of 30 h is better than that of Co-MOF prepared with a reaction time of 18 h and 42 h.

[0252] (5) The water adsorption performance of the Co-MOF materials prepared in Examples 1-3, the Fe-MOF materials prepared in Comparative Examples 2-4, and the Zr-MOF materials prepared in Comparative Examples 5-7 was tested. The specific test method was the same as the test method in Section (1) above.

[0253] The water adsorption properties of the metal-MOF materials prepared in Examples 1-3 and Comparative Examples 2-7 are as follows: Fig.12 As shown. Among them, Fig.12 (a) is the water adsorption performance of the Co-MOF materials prepared in Examples 1-3; Fig.12 (b) is the water adsorption performance of the Fe-MOF material prepared in Comparative Examples 2-4; Fig.12 (c) is the water adsorption performance of the Zr-MOF materials prepared in Comparative Examples 5-7; the horizontal axis is Relative pressure (P / P 0 ) represent relative pressure, the vertical axis Water Uptake (gg -1 ) represent the amount of water adsorption.

[0254] Fig.12 (a) Co-MOF-P-Ads and Co-MOF-P-Des respectively represent the adsorption and desorption curves of the Co-MOF-P material of Example 1, Co-MOF-41-Ads and Co-MOF-41-Des respectively represent the adsorption and desorption curves of the Co-MOF-41 material of Example 2, and Co-MOF-51-Ads and Co-MOF-51-Des respectively represent the adsorption and desorption curves of the Co-MOF-51 material of Example 3; Fig.12 (b) Fe-MOF-11-Ads and Fe-MOF-11-Des respectively represent the adsorption and desorption curves of the Fe-MOF-11 material of Comparative Example 2, Fe-MOF-12-Ads and Fe-MOF-12-Des respectively represent the adsorption and desorption curves of the Fe-MOF-12 material of Comparative Example 3, and Fe-MOF-21-Ads and Fe-MOF-21-Des respectively represent the adsorption and desorption curves of the Fe-MOF-21 material of Comparative Example 4; Fig.12 In (c), Zr-MOF-11-Ads and Zr-MOF-11-Des respectively represent the adsorption and desorption curves of the Zr-MOF-11 material of Comparative Example 5, Zr-MOF-12-Ads and Zr-MOF-12-Des respectively represent the adsorption and desorption curves of the Zr-MOF-12 material of Comparative Example 6, and Zr-MOF-21-Ads and Zr-MOF-21-Des respectively represent the adsorption and desorption curves of the Zr-MOF-21 material of Comparative Example 7.

[0255] Depend on Fig.12It can be seen that the maximum saturated adsorption capacity of the Fe-MOFs material prepared in Comparative Examples 2-4 is only 0.28 g / g, the maximum saturated adsorption capacity of the Zr-MOFs material prepared in Comparative Examples 5-7 is 0.35 g / g, and the maximum saturated adsorption capacity of the Co-MOFs material prepared in Examples 1-3 is 0.98 g / g. The water adsorption performance of the Co-based MOF material prepared in Examples 1-3 of the present invention is significantly better than that of the Zr-based MOF material in Comparative Examples 5-7, and is even better than that of the Zr-based MOF material prepared in Comparative Examples 2-4. This shows that the present invention is selective for the type of metal, and can only have good water adsorption performance when the organic ligand 2.5-dihydroxyphenylenedicarboxylic acid and the specific metal Co are coordinated.

[0256] In summary, the present invention coordinates a specific type of metal and a specific type of organic ligand. The special coordination mode between the two ensures that the structure of the metal-MOF material does not change after being immersed in water for 7 days. After 20 cycles of water adsorption and desorption, it can still reach 96% of the initial load, and the saturated water adsorption capacity can still reach 0.98g / g, with good water stability, water cycle stability and saturated water adsorption capacity.

[0257] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A metal-MOF material, characterized in that: Includes metal and organic ligands; The metal is coordinated with four oxygen atoms provided by the three organic ligands; The metal includes any one of cobalt, chromium and aluminum; The organic ligand includes any one of 2,5-dihydroxybiphenyl dicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid and trimesic acid.

2. The metal-MOF material according to claim 1, characterized in that The molar ratio of the metal to the organic ligand is (0.9-11):

1.

3. The metal-MOF material according to claim 1, characterized in that The metal-MOF material has a porous rod-like structure.

4. The metal-MOF material according to claim 3, characterized in that The width of the porous rod-like structure is 450 nm-1.1 μm; and / or the pore size of the porous rod-like structure is 0.9 nm-110 nm.

5. The metal-MOF material according to claim 1, characterized in that The specific surface area of ​​the metal-MOF material is 1000 cm 2 / g-20000cm 2 / g.

6. The method for preparing the metal-MOF material according to any one of claims 1 to 5, characterized in that: The following steps are involved: The metal salt and the organic ligand are mixed, reacted, and activated to obtain the metal-MOF material; The metal salt includes any one of cobalt salt, chromium salt and aluminum salt; When the metal salt includes a cobalt salt, the cobalt salt includes at least one of cobalt nitrate, cobalt chloride, and cobalt acetate; when the metal salt includes a chromium salt, the chromium salt includes at least one of chromium nitrate, chromium chloride, and chromium acetate; when the metal salt includes an aluminum salt, the aluminum salt includes at least one of aluminum nitrate, aluminum chloride, and aluminum acetate.

7. The preparation method according to claim 6, characterized in that: The molar ratio of the metal salt to the organic ligand is (0.9-11):

1.

8. The preparation method according to claim 6, characterized in that: The reaction temperature is 70° C.-220° C., and the reaction time is 5.5 h-80 h; and / or, the activation temperature is 70° C.-350° C., and the activation time is 3.5 h-52 h.

9. An adsorbent, characterized in that The invention comprises the metal-MOF material according to any one of claims 1 to 5.

10. The adsorbent according to claim 9, characterized in that The adsorbent includes any one of a water adsorbent, a gas adsorbent, and a heavy metal adsorbent.

11. An air purifier or dehumidifier, characterized in that: The invention comprises the adsorbent according to any one of claims 9 to 10.

Images