Metal organic framework composite material, preparation method and application thereof

Abstract

The present application relates to a kind of metal organic framework composite material and its preparation method and application, the metal organic framework composite material includes first MOF material and second MOF material;The first MOF material and second MOF material are compounded by silicon oxide compound;The silicon oxide compound does not completely cover the first MOF material.The metal organic framework composite material provided by the present application avoids the structural design problem of using single MOF to realize multi-component separation, overcomes the defect that the MOF of two kinds of lattices mismatched in prior art is blocked in channel when using high molecular polymer, silicon oxide is used as connector in the present application, it can guarantee that the first MOF material as core is not completely covered, and the metal organic framework composite material after compounding can simultaneously exert the selective adsorption advantage of first MOF material and second MOF material, realizes the adsorption separation of three-component gas.

Description

A metal-organic framework composite material, its preparation method and application Technical Field

[0001] This invention belongs to the field of adsorbent technology, and relates to a metal-organic framework material, and more particularly to a metal-organic framework composite material and its preparation method and application. Background Technology

[0002] Ethylene (C2H4) is a fundamental raw material in the petrochemical industry and a key indicator of a country's petrochemical development level. Currently, ethylene is mainly produced through the cracking of ethane and naphtha, but the cracking products contain impurities such as ethane, carbon dioxide, propylene, propane, hydrogen, and C4+. Industrially, cryogenic distillation is commonly used to separate the mixed gases, but this method is energy-intensive; the energy consumption for separating ethylene and propylene alone accounts for 0.3% of the total energy consumption. Therefore, achieving efficient and energy-saving three-component gas separation is of great significance, especially in one-step separation processes where multiple impurities can be selectively removed simultaneously to purify the desired product.

[0003] The key to achieving efficient gas separation is to select a suitable adsorbent. Compared with traditional materials, porous coordination polymers (PCPs), also known as metal-organic frameworks (MOFs), have advantages such as tunable structure and function, large specific surface area, and high porosity. They have been widely used in fluorescence, catalysis, gas storage and separation methods.

[0004] Modulation of the MOF structure can enable targeted recognition of specific molecules, but this is typically only applicable to binary mixtures. However, gases to be separated, both in nature and in industrial manufacturing, are complex and diverse. While MOFs have been reported for the separation of three-component gases, their structures require de novo design and cannot specifically remove impurity gases. Although MOF materials with multiple specific adsorption sites can be designed, these are mostly obtained accidentally; commercially available MOF materials with only one specific adsorption site are more common.

[0005] In existing technologies, there are no reports on using tandem MOFs for multi-component gas separation. Only a few reports concern the construction of tandem lattice-mismatched MOF materials. For example, polyvinylpyrrolidone (PVP) can be used as a linker to combine lattice-mismatched UiO-66-NH2 and ZIF-8 to obtain U6N@ZIF-8, which is then used for efficient rare earth metal recovery. However, for three-component gas separation, the introduction of polymer materials can block the MOF pores, reducing the reactivity of the MOF composite material.

[0006] Therefore, there is a need to provide a metal-organic framework composite material that is applicable to the separation of three components of gas and has universality, as well as its preparation method and application. Summary of the Invention

[0007] The purpose of this invention is to provide a metal-organic framework composite material, its preparation method and application. The metal-organic framework composite material can give full play to the specific adsorption advantages of different MOF materials, avoid the defect of blocking MOF channels when the composite lattice of polymer is mismatched with MOF materials, and at the same time avoid the structural design problem of achieving three-component gas separation in a single MOF.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a metal-organic framework composite material, the metal-organic framework composite material comprising a first MOF material and a second MOF material;

[0010] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0011] The silicon oxide compound does not completely coat the first MOF material.

[0012] In the metal-organic framework composite material provided by the present invention, the first MOF material and the second MOF material have lattice matching or lattice mismatch, preferably the first MOF material and the second MOF material have lattice mismatch; the lattice mismatched first MOF material and the second MOF material can specifically absorb different gases, realizing the adsorption and separation of three components of gas.

[0013] The metal-organic framework composite material provided by this invention overcomes the defect of existing technologies that use polymers to block the channels of MOFs when composited with two MOFs with mismatched crystal lattices. This invention uses silicon oxide as a linker, which can ensure that the first MOF material, which serves as the core, is not completely covered, so that the composite metal-organic framework composite material can simultaneously exert the specific adsorption advantages of the first MOF material and the second MOF material.

[0014] Preferably, the gas specifically adsorbed by the first MOF material is different from the gas selectively adsorbed by the second MOF material.

[0015] Preferably, the first MOF material includes any one or a combination of at least two of Zn-datz-ipa, UiO-66, ZIF series materials, UiO series materials, HKUST series materials, MIL series materials, IRMOF series materials, CAU series materials, NU series materials, NKU series materials, UTSA series materials, ZJU series materials, NPU series materials, PCP series materials, FJU series materials, CPM series materials, MAF series materials, or M`FSIX-LM materials.

[0016] M`FSIX refers to SiF6 2- and / or TiF6 2- L refers to dipyridine organic ligands; M refers to divalent transition metals.

[0017] Preferably, the first MOF material comprises Zn-datz-ipa and / or UiO-66.

[0018] Preferably, the second MOF material includes any one or a combination of at least two of the following: TIFSIX-2-Cu-i, SIFSIX-3-Ni, ZIF series materials, UiO series materials, HKUST series materials, MIL series materials, IRMOF series materials, CAU series materials, NU series materials, NKU series materials, UTSA series materials, ZJU series materials, NPU series materials, PCP series materials, FJU series materials, CPM series materials, MAF series materials, or M`FSIX-LM materials.

[0019] M`FSIX refers to SiF6 2- and / or TiF6 2- L refers to dipyridine organic ligands; M refers to divalent transition metals.

[0020] Preferably, the second MOF material comprises TIFSIX-2-Cu-i and / or SIFSIX-3-Ni.

[0021] In a second aspect, the present invention provides a method for preparing the metal-organic framework composite material described in the first aspect, the method comprising the following steps:

[0022] The surface of the first MOF material is not completely coated with silicon oxide to obtain MOF1@SiO2; then the second MOF material is coated on the outer layer of MOF1@SiO2 to obtain MOF1@SiO2@MOF2.

[0023] Preferably, the incomplete coating of the silicon oxide compound includes the following steps:

[0024] (1) The first MOF material is ultrasonically dispersed in a solvent to obtain a first dispersion;

[0025] (2) Mix the silicon source with the first dispersion obtained in step (1) and add an alkaline source to achieve incomplete coating of silicon oxide.

[0026] Preferably, the volume ratio of the silicon source in step (2) to the solvent in step (1) is 1:(8-12).

[0027] Preferably, the coating of the second MOF material includes the following steps:

[0028] (3) Disperse MOF1@SiO2 in a solvent by ultrasonication to obtain a second dispersion;

[0029] (4) Add the raw materials for the preparation of the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material.

[0030] Preferably, the preparation method includes the following steps:

[0031] (1) The first MOF material is ultrasonically dispersed in a solvent to obtain a first dispersion;

[0032] (2) Mix the silicon source with the first dispersion obtained in step (1), add an alkaline source to perform incomplete coating of silicon oxide, and obtain MOF1@SiO2;

[0033] (3) Disperse MOF1@SiO2 in a solvent by ultrasonication to obtain a second dispersion;

[0034] (4) The raw materials for the preparation of the second MOF material are added to the second dispersion obtained in step (a) to coat the second MOF material and obtain MOF1@SiO2@MOF2.

[0035] Thirdly, the present invention provides an application of the metal-organic framework composite material described in the first aspect, wherein the metal-organic framework composite material is used for the adsorption and separation of three-component gases.

[0036] The metal-organic framework composite material provided by this invention is suitable for the adsorption and separation of three-component gases. This invention chemically combines two types of MOF materials with single specific adsorption sites. The two types of MOF materials can use their respective specific adsorption sites to adsorb impurity gases, thereby achieving the separation of single-component gases in three-component gases.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The first and second MOF materials with mismatched crystal lattices can selectively absorb different gases, achieving adsorption and separation of three-component gases. The metal-organic framework composite material provided by this invention avoids the structural design problem of using a single MOF to achieve multi-component separation, and overcomes the defect of existing technologies where polymers block the MOF pores when composited with two lattice-mismatched MOFs. This invention uses silicon oxide as a linker, which can ensure that the first MOF material, which serves as the core, is not completely encapsulated, so that the composite metal-organic framework composite material can simultaneously exert the specific adsorption advantages of the first and second MOF materials. Attached Figure Description

[0039] Figure 1 shows the PXRD diffraction pattern of Zn-datz-ipa@SiO2 prepared in Example 1;

[0040] Figure 2 is a scanning electron microscope image of Zn-datz-ipa@SiO2 prepared in Example 1;

[0041] Figure 3 shows the PXRD diffraction pattern of UiO-66@SiO2 prepared in Example 4;

[0042] Figure 4 shows the transmission electron microscope and elemental energy distribution of UiO-66@SiO2 prepared in Example 4;

[0043] Figure 5 shows the PXRD diffraction pattern of Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i prepared in Example 2;

[0044] Figure 6 is a scanning electron microscope image of Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i prepared in Example 2;

[0045] Figure 7 shows the PXRD diffraction pattern of Zn-datz-ipa@SiO2@SIFSIX-3-Ni prepared in Example 3;

[0046] Figure 8 is a scanning electron microscope image of Zn-datz-ipa@SiO2@SIFSIX-3-Ni prepared in Example 3;

[0047] Figure 9 is the PXRD diffraction pattern of UiO-66@SiO2@ZIF-8 prepared in Example 4 of the present invention;

[0048] Figure 10 is a scanning electron microscope image of UiO-66@SiO2@ZIF-8 prepared in Example 4 of the present invention;

[0049] Figure 11 is the PXRD diffraction pattern of UiO-66@SiO2@MOF-74 prepared in Example 5 of the present invention;

[0050] Figure 12 is a scanning electron microscope image of UiO-66@SiO2@MOF-74 prepared in Example 5 of the present invention;

[0051] Figure 13 shows the single-component gas adsorption diagrams of ethylene, ethane, and acetylene prepared by Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i under 298K conditions.

[0052] Figure 14 is a gas breakthrough diagram of the ethylene / ethane / acetylene mixture prepared by Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i under 298K conditions, with the volume ratio of ethylene, ethane and acetylene being 1:1:1.

[0053] Figure 15 shows the single-component gas adsorption diagrams of ethylene, ethane, and carbon dioxide of Zn-datz-ipa@SiO2@SIFSIX-3-Ni prepared in Example 3 of the present invention at 298K.

[0054] Figure 16 is a gas transmission diagram of the ethylene / ethane / carbon dioxide mixture prepared by Zn-datz-ipa@SiO2@SIFSIX-3-Ni in Example 3 of the present invention at 298K, with the volume ratio of ethylene, ethane and carbon dioxide being 1:1:1.

[0055] Figure 17 shows the specific surface area test results of Zn-datz-ipa and Zn-datz-ipa@SiO2 in Example 2. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] An embodiment of the present invention provides a metal-organic framework composite material, the metal-organic framework composite material comprising a first MOF material and a second MOF material;

[0058] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0059] The silicon oxide compound does not completely coat the first MOF material.

[0060] In the metal-organic framework composite material provided by the present invention, the first MOF material and the second MOF material have lattice matching or lattice mismatch, preferably the first MOF material and the second MOF material have lattice mismatch; the lattice mismatched first MOF material and the second MOF material can specifically absorb different gases, realizing the adsorption and separation of three components of gas.

[0061] The metal-organic framework composite material provided by this invention overcomes the defect of existing technologies that use polymers to block the channels of MOFs when composited with two MOFs with mismatched crystal lattices. This invention uses silicon oxide as a linker, which can ensure that the first MOF material, which serves as the core, is not completely covered, so that the composite metal-organic framework composite material can simultaneously exert the specific adsorption advantages of the first MOF material and the second MOF material.

[0062] In some embodiments, the gas specifically adsorbed by the first MOF material is different from the gas specifically adsorbed by the second MOF material.

[0063] In some embodiments, the first MOF material includes any one or a combination of at least two of Zn-datz-ipa, UiO-66, ZIF series materials, UiO series materials, HKUST series materials, MIL series materials, IRMOF series materials, CAU series materials, NU series materials, NKU series materials, UTSA series materials, ZJU series materials, NPU series materials, PCP series materials, FJU series materials, CPM series materials, MAF series materials, or M`FSIX-LM materials, preferably Zn-datz-ipa and / or UiO-66.

[0064] M`FSIX refers to SiF6 2- and / or TiF6 2- L refers to dipyridine organic ligands; M refers to divalent transition metals.

[0065] In some embodiments, the second MOF material includes any one or a combination of at least two of TIFSIX-2-Cu-i, SIFSIX-3-Ni, ZIF series materials, UiO series materials, HKUST series materials, MIL series materials, IRMOF series materials, CAU series materials, NU series materials, NKU series materials, UTSA series materials, ZJU series materials, NPU series materials, PCP series materials, FJU series materials, CPM series materials, MAF series materials, or M`FSIX-LM materials, preferably TIFSIX-2-Cu-i and / or SIFSIX-3-Ni.

[0066] M`FSIX refers to SiF6 2- and / or TiF6 2- L refers to dipyridine organic ligands; M refers to divalent transition metals.

[0067] For example, the TIFSIX-2-Cu-i is suitable for adsorbing acetylene;

[0068] For example, the SIFSIX-3-Ni is suitable for adsorbing carbon dioxide;

[0069] For example, the Zn-datz-ipa is suitable for adsorbing ethane;

[0070] For example, the UiO-66 is suitable for adsorbing ethane.

[0071] One embodiment of the present invention provides a method for preparing metal-organic framework composite materials in certain embodiments, the preparation method comprising the following steps:

[0072] The surface of the first MOF material is not completely coated with silicon oxide to obtain MOF1@SiO2; then the second MOF material is coated on the outer layer of MOF1@SiO2 to obtain MOF1@SiO2@MOF2.

[0073] In some embodiments, the incomplete coating of the silicon oxide compound includes the following steps:

[0074] (1) The first MOF material is ultrasonically dispersed in a solvent to obtain a first dispersion;

[0075] (2) Mix the silicon source with the first dispersion obtained in step (1) and add an alkaline source to achieve incomplete coating of silicon oxide.

[0076] In some embodiments, the solvent in step (1) includes organic solvents and / or water.

[0077] In some embodiments, the organic solvent includes any one or a combination of at least two of methanol, ethanol, or N,N-dimethylformamide. Typical but non-limiting combinations include combinations of methanol and ethanol, ethanol and N,N-dimethylformamide, methanol and N,N-dimethylformamide, or methanol, ethanol, and N,N-dimethylformamide.

[0078] In some embodiments, the temperature of ultrasonic dispersion in step (1) is 20-30°C, for example, it can be 20°C, 22°C, 24°C, 25°C, 28°C or 30°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0079] In some embodiments, the ultrasonic dispersion time in step (1) is 25-35 min, for example, it can be 25 min, 27 min, 28 min, 30 min, 32 min or 35 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0080] In some embodiments, the silicon source in step (2) includes any one or a combination of at least two of tetraethyl orthosilicate, methyl orthosilicate, or alkoxysilane. Typical but non-limiting combinations include a combination of tetraethyl orthosilicate and methyl orthosilicate, a combination of methyl orthosilicate and alkoxysilane, a combination of tetraethyl orthosilicate and alkoxysilane, or a combination of tetraethyl orthosilicate, methyl orthosilicate and alkoxysilane.

[0081] In some embodiments, the mixing in step (2) is completed within 30 minutes.

[0082] In some embodiments, the volume ratio of the silicon source in step (2) to the solvent in step (1) is 1:(8-12), for example, it can be 1:8, 1:9, 1:10, 1:11 or 1:12, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0083] In some embodiments, the alkali source in step (2) includes a NaOH solution with a concentration of 0.08-0.12 mol / L, such as 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, 0.11 mol / L or 0.12 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0084] In some embodiments, the volume ratio of the alkali source in step (2) to the solvent in step (1) is 1:(8-12), for example, it can be 1:8, 1:9, 1:10, 1:11 or 1:12, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0085] In some embodiments, step (2) involves stirring after the addition of the alkali source.

[0086] For example, the stirring temperature is 20-30℃ and the time is ≥24h.

[0087] The stirring temperature is 20-30℃, for example, it can be 20℃, 24℃, 25℃, 27℃, 28℃ or 30℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0088] The stirring time is ≥24h, for example, it can be 24h, 25h, 27h, 28h or 30h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0089] In some embodiments, the coating of the second MOF material includes the following steps:

[0090] (3) Disperse MOF1@SiO2 in a solvent by ultrasonication to obtain a second dispersion;

[0091] (4) Add the raw materials for the preparation of the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material.

[0092] In some embodiments, the solvent in step (3) includes organic solvents and / or water.

[0093] In some embodiments, the organic solvent in the solvent of step (3) includes methanol.

[0094] In some embodiments, the temperature of ultrasonic dispersion in step (3) is 20-30°C, for example, it can be 20°C, 22°C, 24°C, 25°C, 28°C or 30°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0095] In some embodiments, the ultrasonic dispersion time in step (3) is 25-35 min, for example, it can be 25 min, 27 min, 28 min, 30 min, 32 min or 35 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0096] For example, taking TIFSIX-2-Cu-i as the second MOF material, step (4) involves adding the raw materials for preparing the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material, including the following steps:

[0097] Cu(BF4)2 and (NH4)2TiF6 were dissolved in water at independent concentrations of 0.7 mmol / L to obtain solution A1; 4,4'-dipyridineacetylene and triethylamine were dissolved in methanol to obtain solution B1; solutions A1 and B1 were added to the second dispersion and refluxed at a certain temperature to coat the second MOF material.

[0098] For example, taking SIFSIX-3-Ni as the second MOF material, step (4) involves adding the raw materials for preparing the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material, including the following steps:

[0099] Ni(NO3)2, (NH4)2TiF6, and pyrazine were dissolved in water, and MOF1@SiO2 solid particles and triethylamine obtained in step (3) were added to the solution to obtain solution A2; pyrazine was dissolved in water to obtain solution B2 with a concentration of 1.5 mmol / mL; solution B2 was added to solution A2 at room temperature at a rate of 6 mL / h to coat the second MOF material.

[0100] For example, taking ZIF-8 as the second MOF material, step (4) involves adding the raw materials for preparing the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material, including the following steps:

[0101] Zn(NO3)2 was dissolved in a mixed solvent of methanol and water to obtain solution A3; 2-methylimidazole and triethylamine were dissolved in a mixed solvent of methanol and water to obtain solution B3; solutions A3 and B3 were added to the second dispersion and refluxed at a certain temperature to coat the second MOF material.

[0102] For example, taking MOF-74 as the second MOF material, step (4) involves adding the raw materials for preparing the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material, including the following steps:

[0103] Zn(OAc)2 was dissolved in DMF to obtain solution A4; 2,5-dihydroxyterephthalic acid was dissolved in DMF to obtain solution B4; solutions A4 and B4 were added to the second dispersion and refluxed at a certain temperature to coat the second MOF material.

[0104] For example, the TIFSIX-2-Cu-i is suitable for adsorbing acetylene;

[0105] For example, the SIFSIX-3-Ni is suitable for adsorbing carbon dioxide;

[0106] For example, the ZIF-8 is suitable for adsorbing propane;

[0107] For example, the MOF-74 is suitable for adsorbing acetylene.

[0108] In some embodiments, the preparation method includes the following steps:

[0109] (1) The first MOF material is ultrasonically dispersed in a solvent to obtain a first dispersion;

[0110] (2) Mix the silicon source with the first dispersion obtained in step (1), add an alkaline source to perform incomplete coating of silicon oxide, and obtain MOF1@SiO2;

[0111] (3) Disperse MOF1@SiO2 in a solvent by ultrasonication to obtain a second dispersion;

[0112] (4) Add the raw materials for the preparation of the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material and obtain MOF1@SiO2@MOF2.

[0113] One embodiment of the present invention provides an application of a metal-organic framework composite material in certain embodiments, the metal-organic framework composite material being used for the adsorption and separation of three-component gases.

[0114] The metal-organic framework composite material provided by this invention is suitable for the adsorption and separation of three-component gases. This invention chemically combines two types of MOF materials with single specific adsorption sites. The two types of MOF materials can use their respective specific adsorption sites to adsorb impurity gases, thereby achieving the separation of single-component gases in three-component gases.

[0115] To clearly illustrate the technical solution of the present invention, Zn-datz-ipa in the specific embodiments is synthesized according to the method of Cryst. Growth Dws. 2013, 13, 2118-2123; TIFSIX-2-Cu-i is synthesized according to the method of Chen et al., Chem 1, 753-765; and SIFSIX-3-Ni is synthesized according to the method of Chen et al., Chem 1, 753-765.

[0116] Example 1

[0117] This embodiment provides a metal-organic framework composite material, which includes a first MOF material and a second MOF material;

[0118] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0119] The silicon oxide compound does not completely coat the first MOF material;

[0120] The first MOF material is Zn-datz-ipa; the second MOF material is TIFSIX-2-Cu-i;

[0121] The preparation method of the metal-organic framework composite material described in this embodiment includes the following steps:

[0122] (1) Zn-datz-ipa was ultrasonically dispersed in methanol to obtain a first dispersion with a concentration of 0.175 mol / L;

[0123] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0124] (2) Mix tetraethyl orthosilicate with the first dispersion obtained in step (1) within 30 min, add 0.1 mol / L NaOH solution to partially coat silicon oxide, stir at 25℃ for 24 h to obtain Zn-datz-ipa@SiO2; the PXRD diffraction pattern of the obtained Zn-datz-ipa@SiO2 is shown in Figure 1, and the scanning electron microscope image is shown in Figure 2;

[0125] The volume ratio of tetraethyl orthosilicate to methanol in step (1) is 1:10;

[0126] The volume ratio of NaOH solution to methanol in step (1) is 1:10;

[0127] (3) Zn-datz-ipa@SiO2 was ultrasonically dispersed in methanol to obtain a second dispersion with a concentration of 7 mmol / L;

[0128] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0129] (4) Dissolve Cu(BF4)2 and (NH4)2TiF6 in water to obtain solution A, in which the concentrations of Cu(BF4)2 and (NH4)2TiF6 are 0.7 mmol / L; dissolve 4,4'-dipyridineacetylene in methanol to obtain solution B with a concentration of 0.7 mmol / L, and add triethylamine to it at a concentration of 0.7 mmol / L; pump solution A and solution B into the second dispersion at a rate of 20 mL / h using a peristaltic pump, reflux at 80 °C for 24 h, filter, wash three times with methanol to obtain Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i.

[0130] Example 2

[0131] This embodiment provides a metal-organic framework composite material, which includes a first MOF material and a second MOF material;

[0132] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0133] The silicon oxide compound does not completely coat the first MOF material;

[0134] The first MOF material is Zn-datz-ipa; the second MOF material is TIFSIX-2-Cu-i;

[0135] The preparation method of the metal-organic framework composite material described in this embodiment includes the following steps:

[0136] (1) Zn-datz-ipa was ultrasonically dispersed in methanol to obtain a first dispersion with a concentration of 0.35 mol / L;

[0137] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0138] (2) Mix tetraethyl orthosilicate with the first dispersion obtained in step (1) within 30 min, add 0.1 mol / L NaOH solution to incompletely coat silicon oxide, stir at 25°C for 24 h to obtain Zn-datz-ipa@SiO2;

[0139] The volume ratio of tetraethyl orthosilicate to methanol in step (1) is 1:10;

[0140] The volume ratio of NaOH solution to methanol in step (1) is 1:10;

[0141] Figure 17 shows the specific surface area test results of Zn-datz-ipa@SiO2 and Zn-datz-ipa. As can be seen from Figure 17, the specific surface area of ​​the sample did not change before and after coating with silicon oxide. It can be seen that the MOF pores were not covered and the silicon oxide did not completely coat the first MOF material.

[0142] (3) Zn-datz-ipa@SiO2 was ultrasonically dispersed in methanol to obtain a second dispersion with a concentration of 34 mmol / L;

[0143] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0144] (4) Dissolve Cu(BF4)2 and (NH4)2TiF6 in water to obtain solution A, in which the concentrations of Cu(BF4)2 and (NH4)2TiF6 are 57 mmol / L; dissolve 4,4'-dipyridineacetylene in methanol to obtain solution B with a concentration of 57 mmol / L, and add triethylamine to it at a concentration of 0.7 mmol / L; pump solution A and solution B into the second dispersion at a rate of 20 mL / h using a peristaltic pump, reflux at 80 °C for 24 h, filter, wash three times with methanol to obtain Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i.

[0145] The PXRD diffraction pattern of the obtained Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i is shown in Figure 5, and the scanning electron microscope image is shown in Figure 6.

[0146] In this embodiment, the Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i obtained was exchanged with methanol three times a day for three days. After the exchange was completed, the composite material with the removed guest was tested for the adsorption of ethylene, ethane and acetylene gases using a Mack 3Flex activation station.

[0147] Figure 13 shows the single-component gas adsorption diagrams of ethylene, ethane, and acetylene obtained by Zn-datz-ipa@SiO2@TIFSIX-2-Cu-i at 298K.

[0148] The gas penetration curve of the ethylene / ethane / acetylene mixture obtained in this embodiment at 298 K is shown in Figure 14.

[0149] The gas test results show that the composite material has a lower adsorption force for ethylene than ethane and acetylene under low pressure. In pure Zn-datz-ipa, the adsorption force order is ethane > ethylene > acetylene, and in pure TIFSIX-2-Cu-i, the adsorption force order is acetylene > ethylene > ethane. The coated sample can achieve the lowest adsorption force for ethylene and can separate ethylene from the three mixed gases of acetylene, ethylene, and ethane. The dynamic mixed gas breakthrough experiment also confirms that the sample has the ability to separate ethylene from the three mixed gases in one step.

[0150] Example 3

[0151] This embodiment provides a metal-organic framework composite material, which includes a first MOF material and a second MOF material;

[0152] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0153] The silicon oxide compound does not completely coat the first MOF material;

[0154] The first MOF material is Zn-datz-ipa; the second MOF material is SIFSIX-3-Ni;

[0155] The preparation method of the metal-organic framework composite material described in this embodiment includes the following steps:

[0156] (1) Zn-datz-ipa was ultrasonically dispersed in methanol to obtain a first dispersion with a Zn-datz-ipa concentration of 0.35 mol / L;

[0157] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0158] (2) Mix tetraethyl orthosilicate with the first dispersion obtained in step (1) within 30 min, add 0.1 mol / L NaOH solution to incompletely coat silicon oxide, stir at 25°C for 24 h to obtain Zn-datz-ipa@SiO2;

[0159] The volume ratio of tetraethyl orthosilicate to methanol in step (1) is 1:10;

[0160] The volume ratio of NaOH solution to methanol in step (1) is 1:10;

[0161] (3) Ni(NO3)2, (NH4)2SiF6 and pyrazine in a molar ratio of 1:1:2 were dissolved in water to obtain a 6 mL solution A. The concentration of Ni(NO3)2 in solution A was 0.25 mmol / L, the concentration of (NH4)2SiF6 was 0.25 mmol / L, and the concentration of pyrazine was 0.5 mmol / L. Then 60 μL of triethylamine was added to it. Then Zn-datz-ipa@SiO2 was added. The molar ratio of Zn-datz-ipa@SiO2 to pyrazine was 1:4.28. Pyrazine was dissolved in water to obtain a 1.5 mol / L solution B. Solution B was added dropwise to solution A at a rate of 6 mL / h. After the addition was complete, the solution was stirred at room temperature, filtered, and washed with water and ethanol to obtain Zn-datz-ipa@SiO2@SIFSIX-3-Ni.

[0162] The PXRD diffraction pattern of the obtained Zn-datz-ipa@SiO2@SIFSIX-3-Ni is shown in Figure 7, and the scanning electron microscope image is shown in Figure 8.

[0163] The Zn-datz-ipa@SiO2@SIFSIX-3-Ni obtained in this embodiment was exchanged with ethanol three times a day for three days. After the exchange was completed, the composite material with the removed guest was tested for the adsorption of ethylene, ethane and carbon dioxide gases using a Mack 3Flex activation station.

[0164] Figure 15 shows the single-component gas adsorption diagrams of ethylene, ethane, and carbon dioxide obtained by Zn-datz-ipa@SiO2@SIFSIX-3-Ni at 298K.

[0165] Figure 16 shows the gas penetration diagram of the ethylene / ethane / carbon dioxide mixture obtained in this embodiment under 298K conditions.

[0166] The adsorption gas test results show that the composite material has a lower adsorption force for ethylene than for ethane and carbon dioxide under low pressure. In pure Zn-datz-ipa, the adsorption force order is ethane > ethylene > carbon dioxide, and in pure SIFSIX-3-Ni, the adsorption force order is carbon dioxide > ethylene > ethane. The coated sample can achieve the lowest adsorption force for ethylene and can separate ethylene from the three mixed gases of carbon dioxide, ethylene, and ethane. The dynamic mixed gas breakthrough experiment also confirms that the sample has the ability to separate ethylene from the three mixed gases in one step.

[0167] Example 4

[0168] This embodiment provides a metal-organic framework composite material, which includes a first MOF material and a second MOF material;

[0169] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0170] The silicon oxide compound does not completely coat the first MOF material;

[0171] The first MOF material is UiO-66; the second MOF material is ZIF-8;

[0172] The preparation method of the metal-organic framework composite material described in this embodiment includes the following steps:

[0173] (1) UiO-66 was ultrasonically dispersed in methanol to obtain a first dispersion with a UiO-66 concentration of 1.8 mmol / L;

[0174] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0175] (2) Mix tetraethyl orthosilicate with the first dispersion obtained in step (1) within 30 min, add 0.1 mol / L NaOH solution to partially coat silicon oxide, stir at 25℃ for 24 h to obtain UiO-66@SiO2; the PXRD diffraction pattern of the obtained UiO-66@SiO2 is shown in Figure 3, and the transmission electron microscope and elemental energy distribution diagram are shown in Figure 4.

[0176] The volume ratio of tetraethyl orthosilicate to methanol in step (1) is 1:10;

[0177] The volume ratio of NaOH solution to methanol in step (1) is 1:10;

[0178] (3) UiO-66@SiO2 was ultrasonically dispersed in methanol to obtain a second dispersion with a concentration of 0.15 mmol / L;

[0179] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0180] (4) Dissolve Zn(NO3)2 in a mixed solvent of methanol and water (volume ratio of methanol to water is 1:3) to obtain solution A with a Zn(NO3)2 concentration of 6.8 mmol / L; dissolve 2-methylimidazole and triethylamine in a molar ratio of 1.15:1 in a mixed solvent of methanol and water (volume ratio of methanol to water is 1:3) to obtain solution B with a 2-methylimidazole concentration of 31.6 mmol / L; pump solutions A and B into the second dispersion at a rate of 20 mL / h using a peristaltic pump, reflux at 25 °C for 4 h, filter, wash three times with methanol to obtain UiO-66@SiO2@ZIF-8.

[0181] The PXRD diffraction pattern of the obtained UiO-66@SiO2@ZIF-8 is shown in Figure 9, and the scanning electron microscope image is shown in Figure 10.

[0182] Example 5

[0183] This embodiment provides a metal-organic framework composite material, which includes a first MOF material and a second MOF material;

[0184] The first MOF material and the second MOF material are composited using silicon oxide compounds;

[0185] The silicon oxide compound does not completely coat the first MOF material;

[0186] The first MOF material is UiO-66; the second MOF material is MOF-74;

[0187] The preparation method of the metal-organic framework composite material described in this embodiment includes the following steps:

[0188] (1) UiO-66 was ultrasonically dispersed in methanol to obtain a first dispersion with a concentration of 1.8 mmol / L;

[0189] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0190] (2) Mix tetraethyl orthosilicate with the first dispersion obtained in step (1) within 30 min, add 0.1 mol / L NaOH solution to incompletely coat silicon oxide, stir at 25°C for 24 h to obtain UiO-66@SiO2;

[0191] The volume ratio of tetraethyl orthosilicate to methanol in step (1) is 1:10;

[0192] The volume ratio of NaOH solution to methanol in step (1) is 1:10;

[0193] (3) UiO-66@SiO2 was ultrasonically dispersed in N,N-dimethylformamide (DMF) to obtain a second dispersion with a concentration of 0.3 mmol / L;

[0194] The ultrasonic dispersion time was 30 minutes, and the temperature was 25°C.

[0195] (4) Dissolve Zn(OAc)2 in DMF to obtain solution A with a concentration of 24.5 mmol / L; dissolve 2,5-dihydroxyterephthalic acid in DMF to obtain solution B with a concentration of 9.4 mmol / L; use a peristaltic pump to pump solutions A and B into the second dispersion at a rate of 20 mL / h, reflux at 25 °C for 20 h, filter, wash three times with methanol to obtain UiO-66@SiO2@MOF-74.

[0196] The PXRD diffraction pattern of the obtained UiO-66@SiO2@MOF-74 is shown in Figure 11, and the scanning electron microscope image is shown in Figure 12.

[0197] In summary, the first and second MOF materials with mismatched crystal lattices can specifically absorb different gases, achieving adsorption and separation of the three-component gases. The metal-organic framework composite material provided by this invention overcomes the defect of existing technologies where polymers clog the MOF pores when composited with two lattice-mismatched MOFs. This invention uses silicon oxide as a linker, which ensures that the first MOF material, as the core, is not completely encapsulated, allowing the composite metal-organic framework composite material to simultaneously exert the specific adsorption advantages of both the first and second MOF materials.

[0198] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A metal-organic framework composite material, characterized in that, The metal-organic framework composite material includes a first MOF material and a second MOF material; the first MOF material and the second MOF material are composited by a silicon oxide compound; the silicon oxide compound does not completely coat the first MOF material; the gases selectively adsorbed by the first MOF material are different from those selectively adsorbed by the second MOF material.

2. The metal-organic framework composite material according to claim 1, characterized in that, The first MOF material includes any one or a combination of at least two of Zn-datz-ipa, ZIF series materials, UiO series materials, HKUST series materials, MIL series materials or IRMOF series materials.

3. The metal-organic framework composite material according to claim 1, characterized in that, The second MOF material includes any one or a combination of at least two of the following: TIFSIX-2-Cu-i, SIFSIX-3-Ni, ZIF series materials, UiO series materials, HKUST series materials, MIL series materials, or IRMOF series materials.

4. A method for preparing a metal-organic framework composite material as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: the surface of the first MOF material is not completely coated with a silicon oxide compound to obtain MOF1@SiO2; then the second MOF material is coated on the outer layer of MOF1@SiO2 to obtain MOF1@SiO2@MOF2.

5. The preparation method according to claim 4, characterized in that, The incomplete coating of silicon oxide includes the following steps: (1) ultrasonically dispersing the first MOF material in a solvent to obtain a first dispersion; (2) mixing a silicon source with the first dispersion obtained in step (1) and adding an alkaline source to perform incomplete coating of silicon oxide.

6. The preparation method according to claim 5, characterized in that, The volume ratio of the silicon source in step (2) to the solvent in step (1) is 1:(8-12).

7. The preparation method according to claim 4, characterized in that, The coating of the second MOF material includes the following steps: (3) dispersing MOF1@SiO2 in a solvent by ultrasonication to obtain a second dispersion; (4) adding the raw materials for the preparation of the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material.

8. The preparation method according to claim 4, characterized in that, The preparation method includes the following steps: (1) ultrasonically dispersing the first MOF material in a solvent to obtain a first dispersion; (2) mixing a silicon source with the first dispersion obtained in step (1), adding an alkaline source to perform incomplete coating of silicon oxide to obtain MOF1@SiO2; (3) ultrasonically dispersing MOF1@SiO2 in a solvent to obtain a second dispersion; (4) adding the raw materials for preparing the second MOF material to the second dispersion obtained in step (3) to coat the second MOF material to obtain MOF1@SiO2@MOF2.

9. The application of a metal-organic framework composite material according to any one of claims 1-3, characterized in that, When the first MOF material is Zn-datz-ipa and the second MOF material is TIFSIX-2-Cu-i, it is used for the adsorption separation of three-component gases of ethane-acetylene-ethylene; or, when the first MOF material is Zn-datz-ipa and the second MOF material is TIFSIX-3-Ni, it is used for the adsorption separation of three-component gases of ethane-carbon dioxide-ethylene.

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