Rare earth cluster metal organic framework material, preparation method and application thereof

Abstract

The present application relates to a kind of rare earth cluster metal organic framework material and its preparation method and application, the chemical formula of the rare earth cluster metal organic framework material is RE6Y8L 12 (H2O)6;The structural center of the rare earth cluster metal organic framework material is six nuclear rare earth cluster;The RE is rare earth element, Y is halogen, and L is organic ligand.The rare earth cluster metal organic framework material provided by the present application has high structural stability, has porous structure, and has good adsorption performance;Preparation method is simple, and easy to operate, can guarantee the topological structure of material and realize the replacement of organic ligand.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of porous materials, and relates to a metal-organic framework material and a preparation method and application thereof, in particular to a rare earth cluster metal-organic framework material and a preparation method and application thereof. BACKGROUND

[0002] Metal-organic framework (MOF) material is a new type of porous structure crystal material, and has broad application prospects in gas storage, catalysis, luminescence and other fields. The UiO-66 series material is one of the most widely used materials in the MOF material, and the traditional UiO-66 series material mainly takes zirconium (Zr) metal as the structural center. If the metal in the material is replaced, the characteristics of other metals can be brought into the MOF material, greatly widening the application prospect of the material.

[0003] At present, the main choice for replacing the metal zirconium is a rare earth ion. For example, CN104804027A discloses a rare earth metal-organic framework material and a preparation method. The material forms a metal-organic framework structure with a binuclear rare earth metal terbium (Tb) as the structural center and TATAB (4,4',4"-s-triazine-1,3,5,-tri-p-aminobenzoic acid) as the organic ligand.

[0004] CN105330681A discloses a rare earth cluster metal-organic anion framework material and a preparation method thereof. The material takes a hexanuclear rare earth metal europium (Eu) cluster as the metal node, is bridged by a dicarboxylic acid ligand to form a three-dimensional structure, and is prepared by a solvothermal method. The scheme realizes efficient adsorption of cationic organic dyes by using the charge characteristics of the anionic MOF material. Obviously, the adsorption performance has significant selectivity, which greatly limits the application of the material.

[0005] CN107556486A discloses a rare earth organic framework material for fluorescence detection of iron ions and a preparation method thereof. The scheme uses a linear type dicarboxylic acid as an organic ligand to perform a hydrothermal reaction with a metal rare earth salt to obtain a rare earth organic framework material, and realizes fluorescence detection of iron ions by combining the hydroxyl functional group generated in situ by the methoxyl functional group of the organic ligand in the reaction with iron ions. The use of the characteristic reaction of the hydroxyl group and the iron ions makes the selection and application effect of the organic ligand of the material relatively single.

[0006] In the prior art, the UiO-66 series materials mostly use oxygen bridges or hydroxyl bridges as bridging ligands, and the oxygen bridges or hydroxyl bridges are easily attacked in an acidic environment, thereby causing the collapse of the structure, resulting in that the structure has low stability in an acidic condition. In addition, the synthesis method of the material mostly adopts a solvothermal method, and the metal salt and the organic ligand are jointly added to a reaction container for reaction, and the ligand has certain influence on the synthesis of the node cluster, thereby affecting the topological structure of the material, and therefore, the method has certain limitations on the selection of the organic ligand.

[0007] Therefore, in view of the deficiencies of the prior art, it is necessary to provide a rare earth cluster metal organic framework material and a preparation method and application thereof, which can overcome the above-mentioned defects. SUMMARY

[0008] The purpose of the present application is to provide a rare earth cluster metal organic framework material and a preparation method and application thereof, which uses bridging halogen ions and can realize full halogen bridging, thereby improving the stability of the material and significantly improving the adsorption performance of the material.

[0009] To achieve the purpose of the present application, the following technical solutions are adopted:

[0010] In a first aspect, the present application provides a rare earth cluster metal organic framework material, and the chemical formula of the rare earth cluster metal organic framework material is RE6Y8L 12 (H2O)6;

[0011] The structure center of the rare earth cluster metal organic framework material is a six-nuclear rare earth cluster.

[0012] The RE is a rare earth element, Y is halogen, and L is an organic ligand.

[0013] The rare earth cluster metal organic framework material provided by the present application does not introduce oxygen bridges or hydroxyl bridges, thereby avoiding the defect that the oxygen bridges or hydroxyl bridges are easily attacked in an acidic environment, improving the structural stability of the material, and introducing halogen ions with strong coordination crystal field, small structure phonon, and strong electronegativity into the material, thereby significantly improving the adsorption performance of the material.

[0014] Compared with the common binuclear center node, the six-nuclear center node has a larger volume, contains more metals, can provide more coordination sites, and can form more MOF structures with organic ligands. The coordination sites can be more than 30. It is difficult for the binuclear center node to form bridging coordination and three-dimensional MOF structures. At the same time, the rare earth element has a 4f rich electronic configuration, which has an intrinsic magnetism and optical performance that cannot be compared with other metals, can enrich the performance of the organic framework material, and thus expand its application. In addition, the atomic number of the rare earth element is larger, the ionic radius is larger, and the coordination number is higher. Therefore, compared with the six-nuclear zirconium cluster, each rare earth metal ion in the six-nuclear rare earth cluster can still provide one site after completing the same coordination mode as the six-nuclear zirconium cluster. This is an unsaturated metal site that can specifically and quickly adsorb atoms such as water. The trivalent rare earth element forms a specific μ3-F coordination mode with fluorine. Compared with the hydroxyl bridge, the halogen bridge can effectively eliminate the energy loss caused by the high-frequency vibration of O-H, effectively enhance the fluorescence performance, and at the same time, since the hydroxyl bridge is a hydrogen bond donor and the fluorine bridge is a hydrogen bond acceptor, this has an important influence on adsorption and separation.

[0015] Preferably, the rare earth element includes any one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium or yttrium or a combination of at least two of them. Typical but non-limiting combinations include a combination of lanthanum and cerium, a combination of praseodymium and neodymium, a combination of promethium and samarium, a combination of europium and gadolinium, a combination of terbium, dysprosium and holmium, or a combination of erbium, thulium, ytterbium and lutetium.

[0016] Preferably, the halogen includes fluorine.

[0017] Preferably, the organic ligand includes any one of terephthalic acid, 2-amino terephthalic acid, 2-hydroxy terephthalic acid, 2,5-dihydroxy terephthalic acid, 1,4-naphthalene acid, fumaric acid, 2,6-naphthalene acid or diphenic acid or a combination of at least two of them. Typical but non-limiting combinations include a combination of terephthalic acid and 2-amino terephthalic acid, a combination of 2-hydroxy terephthalic acid and 2,5-dihydroxy terephthalic acid, a combination of 1,4-naphthalene acid and fumaric acid, a combination of 2,6-naphthalene acid and diphenic acid, or a combination of terephthalic acid, 2-amino terephthalic acid, 2-hydroxy terephthalic acid, 2,5-dihydroxy terephthalic acid, 1,4-naphthalene acid, fumaric acid, 2,6-naphthalene acid and diphenic acid.

[0018] In a second aspect, the present application provides a preparation method of the rare earth cluster-based metal organic framework material according to the first aspect, and the preparation method comprises the following steps:

[0019] (1) Dissolve the six-nuclear rare earth cluster compound in a solvent to obtain a six-nuclear rare earth cluster compound solution;

[0020] (2) dissolving the organic ligand solute in a solvent to obtain an organic ligand solution;

[0021] (3) mixing the hexanuclear rare earth cluster compound solution and the organic ligand solution, and obtaining the rare earth cluster metal-organic framework material after the mixing is completed.

[0022] The preparation method of the rare earth cluster metal-organic framework material provided by the application can effectively avoid the influence of the ligand on the node cluster synthesis in the solvent thermal one-pot reaction, and further can replace the organic ligand under the premise of ensuring the topological structure, and can effectively solve the problem of determining the number of halogen bridges in the structure, and the process is simple and easy to operate.

[0023] Preferably, the hexanuclear rare earth cluster compound in step (1) includes any one or a combination of at least two of La6F8, Ce6F8, Pr6F8, Nd6F8, Pm6F8, Sm6F8, Eu6F8, Gd6F8, Tb6F8, Dy6F8, Ho6F8, Er6F8, Tm6F8, Tb6F8, Lu6F8, Sc6F8 or Y6F8, and a typical but non-limiting combination includes a combination of La6F8 and Ce6F8, a combination of Pr6F8 and Nd6F8, a combination of Pm6F8 and Sm6F8, a combination of Eu6F8 and Gd6F8, a combination of Tb6F8 and Dy6F8, a combination of Ho6F8, Er6F8 and Tm6F8, or a combination of Tb6F8, Lu6F8, Sc6F8 and Y6F8.

[0024] Preferably, the solvent in step (1) includes an organic solvent; further preferably, the organic solvent is any one or a combination of at least two of ethanol, ethyl acetate, dimethylformamide or methanol, and a typical but non-limiting combination includes a combination of ethanol and ethyl acetate, a combination of dimethylformamide and methanol, a combination of ethanol and methanol, or a combination of ethanol, ethyl acetate, dimethylformamide and methanol.

[0025] Preferably, the concentration of the hexanuclear rare earth cluster compound solution in step (1) is 3-15 mg / mL, for example, can be 3 mg / mL, 6 mg / mL, 10 mg / mL, 12 mg / mL or 15 mg / mL, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0026] Preferably, the organic ligand solute in step (2) includes an organic ligand and / or an organic ligand metal salt.

[0027] Preferably, the organic ligand comprises any one or a combination of at least two of terephthalic acid, 2-amino terephthalic acid, 2-hydroxy terephthalic acid, 2,5-dihydroxy terephthalic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid or diphenic acid, typical but non-limiting combinations include a combination of terephthalic acid and 2-amino terephthalic acid, a combination of 2-hydroxy terephthalic acid and 2,5-dihydroxy terephthalic acid, a combination of 1,4-naphthalene dicarboxylic acid and 2,6-naphthalene dicarboxylic acid, or a combination of terephthalic acid, 2-amino terephthalic acid, 2-hydroxy terephthalic acid, 2,5-dihydroxy terephthalic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid and diphenic acid.

[0028] Preferably, the organic ligand metal salt comprises any one or a combination of at least two of disodium terephthalate, disodium 2-amino terephthalate, disodium 2-hydroxy terephthalate, disodium 2,5-dihydroxy terephthalate, disodium 1,4-naphthalene dicarboxylate, dilithium terephthalate, dilithium 2-amino terephthalate, dilithium 2-hydroxy terephthalate, dilithium 2,5-dihydroxy terephthalate, dilithium 1,4-naphthalene dicarboxylate or disodium fumarate, typical but non-limiting combinations include a combination of disodium terephthalate and disodium 2-amino terephthalate, a combination of disodium 2-hydroxy terephthalate and disodium 2,5-dihydroxy terephthalate, a combination of dilithium terephthalate and dilithium 2-amino terephthalate, a combination of dilithium 2-hydroxy terephthalate and dilithium 2,5-dihydroxy terephthalate, a combination of disodium terephthalate, disodium 2-amino terephthalate, disodium 2-hydroxy terephthalate, disodium 2,5-dihydroxy terephthalate and disodium 1,4-naphthalene dicarboxylate, or a combination of dilithium terephthalate, dilithium 2-amino terephthalate, dilithium 2-hydroxy terephthalate, dilithium 2,5-dihydroxy terephthalate and dilithium 1,4-naphthalene dicarboxylate.

[0029] Preferably, the solvent in step (2) comprises an organic solvent and / or water, the organic solvent is preferably dimethylformamide and / or diethylformamide.

[0030] Preferably, the concentration of the organic ligand solution in step (2) is 0.009-0.12 mol / L, for example, it can be 0.009 mol / L, 0.02 mol / L, 0.04 mol / L, 0.08 mol / L, 0.1 mol / L or 0.12 mol / L, but is not limited to the listed values, other values not listed in the value range are also applicable.

[0031] Preferably, the volume ratio of the rare earth cluster solution to the organic ligand solution in step (3) is 1:(0.3-1.5), for example, it can be 1:0.3, 1:0.5, 1:0.8, 1:1.2 or 1:1.5, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0032] In a third aspect, the present application also provides an application of the rare earth cluster metal organic framework material according to the first aspect, in particular, the rare earth cluster metal organic framework material is used for gas adsorption.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] (1) The rare earth cluster metal organic framework material provided by the present application has high structural stability, a porous structure and good adsorption performance.

[0035] (2) The preparation method provided by the present application is simple and easy to operate, and can ensure the topological structure of the material and realize replacement of the organic ligand. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Structure schematic diagram of the rare earth cluster metal organic framework material prepared for the present application embodiment 1.

[0037] Figure 2 PXRD diffraction pattern of the rare earth cluster metal organic framework material prepared for the present application embodiments 1-5.

[0038] Figure 3 PXRD diffraction pattern of the rare earth cluster metal organic framework material prepared for the present application embodiment 6.

[0039] Figure 4 PXRD diffraction pattern of the rare earth cluster metal organic framework material prepared for the present application embodiment 7.

[0040] Figure 5 PXRD diffraction pattern of the rare earth cluster metal organic framework material prepared for the present application embodiment 9.

[0041] Figure 6 77K nitrogen adsorption curve of the rare earth cluster metal organic framework material prepared for the present application embodiments 1-5; wherein, P / P0 is the relative pressure of the gas.

[0042] Figure 7 77K nitrogen adsorption curve of the rare earth cluster metal organic framework material prepared for the present application embodiments 6, 7 and 9; wherein, P / P0 is the relative pressure of the gas. DETAILED DESCRIPTION

[0043] The technical solutions of the present application are further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0044] In order to clearly illustrate the technical solutions, in the specific embodiments of the present application, the hexanuclear rare earth cluster compound is a compound disclosed in CN111292909B, and an exemplary synthesis method includes the following steps:

[0045] The rare earth metal source is uniformly dispersed in an organic solvent, and then a fluorine source is added to the organic solvent in which the rare earth metal is dispersed, with a mass ratio of the rare earth metal source to the fluorine source being (20-5):1, to obtain a reaction system A; the reaction system A is subjected to thermal reaction at 80-160℃ for 24-72h in the organic solvent, and the reaction system A after the thermal reaction is subjected to filtration of supernatant, low-temperature crystallization, and washing to obtain the hexanuclear rare earth cluster compound.

[0046] The rare earth metal source includes a rare earth metal salt, a rare earth metal oxide, or a rare earth metal element.

[0047] The fluorine source includes hydrofluoric acid, a metal fluoride, or an ammonium fluoride.

[0048] The organic solvent includes dimethylformamide, methanol, acetonitrile, dimethyl sulfoxide, ethanol, or ethyl acetate.

[0049] In order to clearly illustrate the technical solutions, in the specific embodiments of the present application, the crystal structure of the prepared rare earth cluster metal organic framework material is determined by using a polycrystalline X-ray diffraction method (PXRD), and the porous structure and adsorption performance of the prepared rare earth cluster metal organic framework material are characterized by using a BET specific surface area method and a 77K nitrogen adsorption method.

[0050] Example 1

[0051] The present embodiment provides a preparation method of a rare earth cluster metal organic framework material, which includes the following steps:

[0052] (1) Dissolve the hexanuclear rare earth cluster compound Gd6F8 in ethanol to obtain a hexanuclear rare earth cluster compound solution with a concentration of 15mg / mL;

[0053] (2) Dissolve terephthalic acid in dimethylformamide to obtain a terephthalic acid solution with a concentration of 0.04mol / L;

[0054] (3) Mix the hexanuclear rare earth cluster compound solution and the terephthalic acid solution in a volume ratio of 1:1.5, and the mixing temperature is 130℃ and the mixing time is 72h.

[0055] In the present embodiment, the hexanuclear rare earth cluster compound Gd6F8 is prepared by the following method:

[0056] Gd(III) triflate (0.75 g) and NH4F (0.074 g) were added into 8 mL of dimethylformamide and stirred for 10 min to obtain a mixture; the mixture was transferred into a polytetrafluoroethylene-lined stainless steel reactor, and the reactor was placed in an oven at 80°C and heated for 72 h under the pressure generated naturally in the reactor; after the reaction was completed, the reactor was naturally cooled to room temperature, and the supernatant in the reactor was taken out, filtered, cooled and crystallized at -40°C for 24 h, and washed with cold dimethylformamide three times to obtain Gd6F8 crystals.

[0057] The rare earth cluster metal organic framework material prepared in this example takes terephthalic acid as an organic ligand, and is named NPU-66. The structural schematic diagram of the material is shown in Figure 1 The PXRD diffraction pattern is shown in Figure 2 The nitrogen adsorption curve at 77 K is shown in Figure 6 The BET specific surface area is 986 m 2 / g. The material has high purity, good crystallinity, a porous structure, and good nitrogen adsorption.

[0058] Example 2

[0059] The present example provides a preparation method of a rare earth cluster metal organic framework material, which comprises the following steps:

[0060] (1) Dissolving hexanuclear rare earth cluster compound Gd6F8 in ethyl acetate to obtain a hexanuclear rare earth cluster compound solution with a concentration of 15 mg / mL;

[0061] (2) Dissolving 2-amino terephthalic acid disodium in water to obtain a 2-amino terephthalic acid disodium solution with a concentration of 0.04 mol / L;

[0062] (3) Mixing the hexanuclear rare earth cluster compound solution and the 2-amino terephthalic acid disodium solution in a volume ratio of 1:1.5 by stirring, and stirring for 12 h to obtain.

[0063] In this example, the hexanuclear rare earth cluster compound Gd6F8 is the same as in Example 1.

[0064] The rare earth cluster metal organic framework material prepared in this example takes 2-amino terephthalic acid as an organic ligand, and is named NPU-66-NH2. The PXRD diffraction pattern of the material is shown in Figure 2 The nitrogen adsorption curve at 77 K is shown in Figure 6 The BET specific surface area is 771 m 2 / g. The material has high purity, good crystallinity, a porous structure, and good nitrogen adsorption.

[0065] Example 3

[0066] The embodiment provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0067] (1) dissolving hexanuclear rare earth cluster compound Gd6F8 in ethyl acetate to obtain a hexanuclear rare earth cluster compound solution with a concentration of 15 mg / mL;

[0068] (2) dissolving di-lithium 2-hydroxyterephthalic acid in water to obtain a di-lithium 2-hydroxyterephthalic acid solution with a concentration of 0.05 mol / L;

[0069] (3) mixing the hexanuclear rare earth cluster compound solution and the di-lithium 2-hydroxyterephthalic acid solution in a volume ratio of 1:1.5, and the mixing mode is stirring, and the stirring is performed for 5 s.

[0070] In the embodiment, the hexanuclear rare earth cluster compound Gd6F8 is the same as that in the embodiment 1.

[0071] The rare earth cluster metal organic framework material prepared in the embodiment is named NPU-66-OH with 2-hydroxyterephthalic acid as an organic ligand, and a PXRD diffraction graph of the material is as shown in Figure 2 , which is in good agreement with the simulation result, and a 77K nitrogen adsorption curve is as shown in Figure 6 , a BET specific surface area is 756 m 2 / g, the material has high purity, good crystallinity, a porous structure and good nitrogen adsorption.

[0072] Embodiment 4

[0073] The embodiment provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0074] (1) dissolving hexanuclear rare earth cluster compound Gd6F8 in ethanol to obtain a hexanuclear rare earth cluster compound solution with a concentration of 12 mg / mL;

[0075] (2) dissolving 2,5-dihydroxyterephthalic acid in diethylformamide to obtain a 2,5-dihydroxyterephthalic acid solution with a concentration of 0.06 mol / L;

[0076] (3) mixing the hexanuclear rare earth cluster compound solution and the 2,5-dihydroxyterephthalic acid solution in a volume ratio of 1:1.2, and the mixing temperature is 120 DEG C and the mixing time is 80 h.

[0077] In the embodiment, the hexanuclear rare earth cluster compound Gd6F8 is the same as that in the embodiment 1.

[0078] The rare earth cluster metal organic framework material prepared in the embodiment takes 2,5-dihydroxyterephthalic acid as an organic ligand, is named NPU-66-2OH, and the PXRD diffraction pattern of the material is as shown in Figure 2 The 77K nitrogen adsorption curve is as shown in Figure 6 The BET specific surface area is 662m 2 / g, the material has high purity, good crystallinity, a porous structure, and good nitrogen adsorption.

[0079] Embodiment 5

[0080] The embodiment provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0081] (1) dissolving hexanuclear rare earth cluster compound Gd6F8 in ethanol to obtain a hexanuclear rare earth cluster compound solution with a concentration of 10 mg / mL;

[0082] (2) dissolving 1,4-naphthalene dicarboxylic acid in diethylformamide to obtain a 1,4-naphthalene dicarboxylic acid solution with a concentration of 0.08 mol / L;

[0083] (3) mixing the hexanuclear rare earth cluster compound solution and the 1,4-naphthalene dicarboxylic acid solution in a volume ratio of 1:1, wherein the mixing temperature is 150 DEG C, and the mixing time is 60 h.

[0084] In the embodiment, the hexanuclear rare earth cluster compound Gd6F8 is the same as that in Embodiment 1.

[0085] The rare earth cluster metal organic framework material prepared in the embodiment takes 1,4-naphthalene dicarboxylic acid as an organic ligand, is named NPU-66-NDC, and the PXRD diffraction pattern of the material is as shown in Figure 2 The 77K nitrogen adsorption curve is as shown in Figure 6 The BET specific surface area is 579m 2 / g, the material has high purity, good crystallinity, a porous structure, and good nitrogen adsorption.

[0086] Embodiment 6

[0087] The embodiment provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0088] (1) dissolving hexanuclear rare earth cluster compound Gd6F8 in methanol to obtain a hexanuclear rare earth cluster compound solution with a concentration of 10 mg / mL;

[0089] (2) dissolving sodium hydrogen fumarate in water to obtain a sodium hydrogen fumarate solution with a concentration of 0.12 mol / L;

[0090] (3) mixing the hexanuclear rare earth cluster compound solution and the sodium hydrogen fumarate solution in a volume ratio of 1:0.3, the mixing mode being stirring, and the time being 12 h.

[0091] The hexanuclear rare earth cluster compound Gd6F8 in this embodiment is the same as that in Embodiment 1.

[0092] The rare earth cluster metal organic framework material prepared in this embodiment takes fumaric acid as an organic ligand, is named NPU-65, and the PXRD diffraction pattern of the material is shown in Figure 3 , which is in good agreement with the simulation result, the 77K nitrogen adsorption curve is shown in Figure 7 , and the BET specific surface area is 563 m 2 / g. The material has high purity, good crystallinity, a porous structure, and good nitrogen adsorption property.

[0093] Embodiment 7

[0094] The embodiment provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0095] (1) dissolving the hexanuclear rare earth cluster compound Gd6F8 in a mixed solution of ethanol and dimethylformamide, the volume ratio of ethanol and dimethylformamide being 1:2, to obtain a hexanuclear rare earth cluster compound solution with a concentration of 7 mg / mL;

[0096] (2) dissolving sodium 2,6-naphthalene dicarboxylate in water to obtain a sodium 2,6-naphthalene dicarboxylate solution with a concentration of 0.05 mol / L;

[0097] (3) mixing the hexanuclear rare earth cluster compound solution and the sodium 2,6-naphthalene dicarboxylate solution in a volume ratio of 1:0.4, the mixing temperature being 85 ℃, and the time being 72 h.

[0098] The hexanuclear rare earth cluster compound Gd6F8 in this embodiment is the same as that in Embodiment 1.

[0099] The rare earth cluster metal organic framework material prepared in this embodiment takes 2,6-naphthalene dicarboxylic acid as an organic ligand, is named NPU-67, and the PXRD diffraction pattern of the material is shown in Figure 4 , which is in good agreement with the simulation result, the 77K nitrogen adsorption curve is shown in Figure 7 , and the BET specific surface area is 1064 m 2 / g. The material has high purity, good crystallinity, a porous structure, and good nitrogen adsorption property.

[0100] Embodiment 8

[0101] The embodiment provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0102] (1) Dissolve the hexanuclear rare earth cluster Gd6F8 in dimethylformamide to obtain a hexanuclear rare earth cluster solution with a concentration of 3 mg / L;

[0103] (2) Dissolve 2,6-naphthalene dicarboxylic acid in dimethylformamide to obtain a 2,6-naphthalene dicarboxylic acid solution with a concentration of 0.03 mol / L;

[0104] (3) Mix the hexanuclear rare earth cluster solution and the 2,6-naphthalene dicarboxylic acid solution in a volume ratio of 1:0.5, and the mixing temperature is 150°C for 12 h.

[0105] The hexanuclear rare earth cluster Gd6F8 in this example is the same as that in Example 1.

[0106] The rare earth cluster metal organic framework material prepared in this example uses 2,6-naphthalene dicarboxylic acid as an organic ligand, which is the same as the material prepared in Example 8.

[0107] Example 9

[0108] The present example provides a preparation method of a rare earth cluster metal organic framework material, which comprises the following steps:

[0109] (1) Dissolve the hexanuclear rare earth cluster Gd6F8 in a mixed solution of ethanol and ethyl acetate with a volume ratio of 1.5:1 to obtain a hexanuclear rare earth cluster solution with a concentration of 6 mg / mL;

[0110] (2) Dissolve sodium diphenic acid in water to obtain a sodium diphenic acid solution with a concentration of 0.1 mol / L;

[0111] (3) Mix the hexanuclear rare earth cluster solution and the sodium diphenic acid solution in a volume ratio of 1:0.7, and the mixing temperature is 85°C for 72 h.

[0112] The hexanuclear rare earth cluster Gd6F8 in this example is the same as that in Example 1.

[0113] The rare earth cluster metal organic framework material prepared in this example uses diphenic acid as an organic ligand, which is named NPU-68, and the PXRD diffraction pattern of the material is shown in Figure 5 , which is in good agreement with the simulation results. The 77K nitrogen adsorption curve is shown in Figure 7 , the BET specific surface area is 1336 m 2 / g, the material has high purity, good crystallinity, porous structure, and good nitrogen adsorption.

[0114] Example 10

[0115] The present example provides a preparation method of a rare earth cluster metal organic framework material, which comprises the following steps:

[0116] (1) Dissolve the hexanuclear rare earth cluster compound Gd6F8 in dimethylformamide to obtain a hexanuclear rare earth cluster compound solution with a concentration of 3 mg / L;

[0117] (2) Dissolve the diphenic acid in dimethylformamide to obtain a diphenic acid solution with a concentration of 0.009 mol / L;

[0118] (3) Mix the hexanuclear rare earth cluster compound solution and the diphenic acid solution at a volume ratio of 1:0.5, and the mixing temperature is 90°C and the mixing time is 72 h.

[0119] The hexanuclear rare earth cluster compound Gd6F8 in this example is the same as that in Example 1.

[0120] The rare earth cluster metal organic framework material prepared in this example has the same structure as the NPU-66 prepared in Example 1.

[0121] Example 11

[0122] The present example provides a preparation method of a rare earth cluster metal organic framework material, and the preparation method comprises the following steps:

[0123] (1) Dissolve the hexanuclear rare earth cluster compound Nd6F8 in methanol to obtain a hexanuclear rare earth cluster compound solution with a concentration of 8 mg / mL;

[0124] (2) Dissolve 2,5-dihydroxyterephthalic acid in dimethylformamide to obtain a 2,5-dihydroxyterephthalic acid solution with a concentration of 0.1 mol / L;

[0125] (3) Mix the hexanuclear rare earth cluster compound solution and the 2,5-dihydroxyterephthalic acid solution at a volume ratio of 1:1, and the mixing temperature is 100°C and the mixing time is 75 h.

[0126] The hexanuclear rare earth cluster compound Nd6F8 in this example is prepared by the following method:

[0127] Add 0.75 g of neodymium pivalate and 0.074 g of ammonium fluoride to 8 mL of ethyl acetate, and stir for 10 min to obtain a mixture; transfer the mixture into a polytetrafluoroethylene-lined stainless steel reaction kettle, and place the reaction kettle in an oven at 160°C, and heat under the pressure generated by the reaction kettle for 24 h; after the reaction is completed, naturally cool the reaction kettle to room temperature, take out the supernatant in the kettle, filter, cool and crystallize at minus 40°C for 24 h, and wash with cold dimethylformamide three times to obtain Nd6F8 crystals.

[0128] The rare earth cluster metal organic framework material obtained in this example has the same structure as the NPU-66 prepared in Example 1.

[0129] In summary, the rare earth cluster metal organic framework material provided by the application has high structural stability, a porous structure and good adsorption performance; the preparation method provided by the application is simple in process and easy to operate, and can guarantee the topological structure of the material and realize replacement of the organic ligand.

[0130] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the application, which can be easily thought of by any person skilled in the art, falls within the protection scope and disclosure scope of the application.

Claims

1. A method for preparing a rare earth cluster-based metal-organic framework material, characterized in that, The preparation method includes the following steps: (1) Dissolve the hexanuclear rare earth cluster compound in a solvent to obtain a hexanuclear rare earth cluster compound solution; (2) Dissolve the organic ligand solute in a solvent to obtain an organic ligand solution; (3) Mix the hexanuclear rare earth cluster compound solution and the organic ligand solution, and obtain the rare earth cluster-based metal-organic framework material after mixing; The synthesis method of the hexanuclear rare earth cluster compound includes the following steps: uniformly dispersing a rare earth metal source in an organic solvent, then adding a fluorine source to the organic solvent containing the dispersed rare earth metal at a mass ratio of rare earth metal source to fluorine source of (20-5):1 to obtain reaction system A; subjecting reaction system A to a thermal reaction at 80-160℃ for 24-72 hours, filtering the supernatant from reaction system A after the thermal reaction, crystallizing at low temperature, and washing to obtain the hexanuclear rare earth cluster compound; the fluorine source includes hydrofluoric acid, metal fluoride, or ammonium fluoride. The rare earth cluster-based metal-organic framework material prepared by the method has the chemical formula RE6Y8L. 12 (H2O)6; the structural center of the rare earth cluster-based metal-organic framework material is a hexanuclear rare earth cluster; wherein, RE is a rare earth element, the rare earth element includes gadolinium, Y is fluorine, and L is an organic ligand; The organic ligands include any one or a combination of at least two of the following: terephthalic acid, 2-aminoterephthalic acid, 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 1,4-naphthalic acid, fumaric acid, 2,6-naphthalic acid, or biphenyl phthalic acid.

2. The preparation method according to claim 1, characterized in that, The solvent mentioned in step (1) includes organic solvents.

3. The preparation method according to claim 2, characterized in that, The organic solvent is any one or a combination of at least two of ethanol, ethyl acetate, dimethylformamide, or methanol.

4. The preparation method according to claim 1, characterized in that, The concentration of the hexanuclear rare earth cluster compound solution in step (1) is 3-15 mg / mL.

5. The preparation method according to claim 1, characterized in that, The organic ligand solute in step (2) includes organic ligands and / or organic ligand metal salts.

6. The preparation method according to claim 5, characterized in that, The organic ligand metal salt includes any one or a combination of at least two of the following: disodium terephthalate, disodium 2-aminoterephthalate, disodium 2-hydroxyterephthalate, disodium 2,5-dihydroxyterephthalate, disodium 1,4-naphthalic acid, dilithium terephthalate, dilithium 2-aminoterephthalate, dilithium 2-hydroxyterephthalate, dilithium 2,5-dihydroxyterephthalate, dilithium 1,4-naphthalic acid, or disodium fumarate.

7. The preparation method according to claim 1, characterized in that, The solvents mentioned in step (2) include organic solvents and / or water.

8. The preparation method according to claim 7, characterized in that, The organic solvent includes dimethylformamide and / or diethylformamide.

9. The preparation method according to claim 1, characterized in that, The concentration of the organic ligand solution in step (2) is 0.009-0.12 mol / L.

10. The preparation method according to claim 1, characterized in that, The volume ratio of the hexanuclear rare earth cluster compound solution to the organic ligand solution in step (3) is 1:(0.3-1.5).

11. An application of a rare earth cluster-based metal-organic framework material prepared by the preparation method according to any one of claims 1-10, characterized in that, The rare-earth cluster-based metal-organic framework material is used for gas adsorption.

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