Aluminum-based metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses an aluminum-based metal organic framework material and a preparation method and application thereof.The preparation method comprises the steps that an organic ligand and a solvent I are mixed at the room temperature, then deprotonation alkali is added, and a mixed solution A is formed; dissolving an aluminum source in a solvent I at room temperature to form a mixed solution B; and mixing the mixed solution A and the mixed solution B, crystallizing at 25-200 DEG C for 0.5-72 hours, mixing the obtained metal organic framework material precursor with a solvent II, then adding a modified ligand, and modifying the formed mixed solution at 25-200 DEG C to obtain the metal organic framework material. The carbon capture metal organic framework material is prepared by synthesizing the metal organic framework material precursor and carrying the solvent-assisted modified ligand, the adsorption acting force of the metal organic framework on CO2 can be enhanced, the CO2 adsorption separation performance is improved, the synthesis process is mild, large-scale preparation is easy, the adsorption performance is good, the regeneration energy consumption is low, and the carbon capture metal organic framework material is suitable for industrial production. The method can be used for CO2 capture in industrial and living places.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation and adsorption, and more specifically, to an aluminum-based metal-organic framework material, a preparation method thereof, and an application thereof. Background Art

[0002] The continuous increase in the concentration of carbon dioxide in the atmosphere is recognized as the main cause of global warming. Therefore, carbon emission reduction has become an important consensus among countries around the world to address climate change. Carbon dioxide capture and separation are the most direct and effective means of carbon emission reduction. The chemical absorption method based on liquid amine solution is the most commonly used industrial decarbonization method at present, which has a high capture efficiency, but has defects such as equipment corrosion, amine leakage, and high regeneration energy consumption. In contrast, solid adsorbents do not require additional absorbent supplementation during the carbon capture process, can be recycled, and have lower energy consumption for regeneration, showing great potential in the field of carbon capture. The amine-supported solid adsorbent materials exhibit excellent CO2 adsorption performance and selectivity. Such composite materials have the dual functions of physical adsorption of porous structure and chemical adsorption of amine groups, greatly improving the adsorption capacity of carbon dioxide. However, amine-based solid adsorbents still face great challenges in practical applications. Disadvantages such as poor cyclic stability, low hydrothermal stability, and high regeneration energy consumption limit their large-scale application. In recent years, metal-organic framework materials have shown extremely high CO2 adsorption selectivity and adsorption capacity due to their characteristics such as large specific surface area, high porosity, structural designability, and controllability, showing great advantages and industrial application potential in carbon capture.

[0003] With the in-depth research on carbon capture by metal-organic framework materials, it is found that the pore structure and surface properties of metal-organic framework materials formed by the complex coordination of a single type of metal node and organic ligand can no longer meet the actual application requirements. In particular, there are still many challenges in making metal-organic framework materials have high adsorption capacity, high adsorption selectivity, and low adsorption heat. High adsorption capacity can ensure that the adsorbent can effectively adsorb the target gas, high adsorption selectivity ensures that the adsorbent can effectively separate from multi-component gases, and low adsorption heat ensures that the adsorbent has low regeneration energy consumption. Therefore, it is necessary to precisely design and control the preparation through reticular chemistry to optimize the pore structure and surface properties of metal-organic frameworks and improve the performance of the adsorbent. Among them, post-modification of metal-organic framework materials is a feasible method, and common modification methods include metal exchange, ligand exchange, and doping or replacement of guest molecules.

[0004] In recent years, a series of metal-organic framework adsorbents for CO2 adsorption have been disclosed. Chinese Patent No. CN116239786A discloses a fumaric acid metal-organic framework adsorbent with good CO2 adsorption performance. This adsorbent uses zirconium, cerium, and hafnium as metal nodes, and its adsorption capacity is up to about 4 mmol / g at room temperature and atmospheric pressure. However, the cost of cerium and hafnium metal salts with better usage effects is relatively high. Chinese Patent No. CN103665015A discloses an aluminum-based dual-ligand metal-organic framework adsorbent with good CO2 adsorption performance. This adsorbent uses aluminum as the metal node, and 2-aminoterephthalic acid and 1,4-naphthalenedicarboxylic acid as ligands, and the cost of the ligands used is also very high. Chinese Patent No. CN110496604A discloses a bimetallic adsorbent Co-Ni-MOF-74 with excellent CO2 adsorption performance. Its synthesis uses a microwave-ultraviolet-ultrasonic trinity synthesis reactor, which is difficult to achieve large-scale industrial production.

[0005] In summary, the existing metal-organic framework adsorbents generally have problems such as poor performance, high cost, and difficulty in large-scale preparation. Therefore, developing a metal-organic framework adsorbent with low cost, simple synthesis method, and excellent adsorption capacity is an urgent problem to be solved. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art, and provide an aluminum-based metal-organic framework material, its preparation method and application. Through two steps of synthesizing the metal-organic framework material precursor and solvent-assisted modification ligand loading, using a low-cost single-ligand metal-organic framework as the precursor, and adjusting the structure and pore environment of the metal-organic framework through the solvent-assisted ligand exchange strategy, a carbon capture metal-organic framework material is prepared, thereby further enhancing the adsorption force of the metal-organic framework on CO2 and improving the CO2 adsorption and separation performance. This method has the advantages of mild synthesis process, easy large-scale preparation, good adsorption performance, and low regeneration energy consumption, and can be used for CO2 capture in industrial production sites and living sites, and is a new type of adsorbent with great prospects.

[0007] To achieve the above purpose, the technical solution of the present invention is as follows:

[0008] A preparation method of an aluminum-based metal-organic framework material, comprising the following steps:

[0009] (1) Mix the organic ligand and Solvent I at room temperature. The organic ligand is a carboxyl-containing ligand, and then add a deprotonating base to form a mixed solution A. Dissolve the aluminum source in Solvent I at room temperature to form a mixed solution B. Mix the mixed solution A and the mixed solution B, crystallize at 25 °C to 200 °C for 0.5 h to 72 h, then cool to room temperature, and successively filter, wash, and dry to obtain a metal-organic framework material precursor.

[0010] (2) Mix the metal-organic framework material precursor and Solvent II, and then add a modified ligand. The modified ligand is a small molecule anion. Modify the formed mixture at 25 °C to 200 °C for 2 h to 96 h. After the reaction ends, filter, wash, and dry to obtain an aluminum-based metal-organic framework material.

[0011] Optionally, in step (1), the crystallization temperature is preferably 50 °C to 180 °C. At this temperature, both a short synthesis time and a high yield are ensured. To achieve the mild preparation of the metal-organic framework material precursor, the crystallization temperature is more preferably 50 °C to 100 °C.

[0012] Optionally, in step (1), the crystallization time is preferably 1 h to 48 h, and more preferably 2 h to 24 h.

[0013] Optionally, in step (2), the modification temperature is preferably 60 °C to 150 °C, and the modification time is preferably 8 h to 24 h. At this temperature and reaction time, sufficient exchange and loading of the organic ligand in the precursor with the modification are ensured.

[0014] Optionally, in step (1), the molar ratio of the organic ligand, the aluminum source (calculated as Al 3+ ), and the deprotonating base (calculated as the number of protons binding H) is 1:(2 - 2.4):(2.0 - 2.1). To improve the utilization rate of raw materials, preferably, the molar ratio of the organic ligand, the aluminum source (calculated as Al 3+ ), and the deprotonating base (calculated as the number of protons binding H) is 1:(2 - 2.1):(2.0 - 2.05).

[0015] Optionally, in step (1), the total addition amount of Solvent I is 2 times to 250 times the total mass of the organic ligand and the aluminum source (calculated as Al 3+ ). To improve the crystallinity and recovery rate of the metal-organic framework material precursor, preferably, the total addition amount of Solvent I is 5 times to 250 times the total mass of the organic ligand and the aluminum source (calculated as Al 3+ ), and more preferably 5 times to 200 times.

[0016] Optionally, in step (2), the addition amount of the modified ligand is 0.05 to 5 times the molar amount of the organic ligand in the metal-organic framework material precursor.

[0017] Optionally, in step (2), the total addition amount of the solvent II is 5 to 40 times the total mass of the metal-organic framework material precursor. To improve the economy of the modification process and the loading rate of the modified ligand, preferably, the total addition amount of the solvent II is 10 to 30 times the total mass of the metal-organic framework material precursor.

[0018] Optionally, in step (2), the concentration of the modified ligand in the solvent II is 1 mol / L to 30 mol / L. The concentration of the ligand in the solution affects the position and quantity of the exchange, thereby affecting the adsorption performance of the adsorbent. More preferably, it is 10 mol / L to 25 mol / L.

[0019] Optionally, in step (1), the organic ligand includes at least one of fumaric acid, malonic acid, isophthalic acid, succinic acid, phthalic acid, trans-cyclohexanedicarboxylic acid, dihydroxyfumaric acid, diamino fumaric acid, dihydroxy maleic acid, diamino maleic acid, malic acid, aspartic acid, 5-methylisophthalic acid, benzoquinone, furandicarboxylic acid, pyrazole-3,5-dicarboxylic acid, 1H-pyrrole-2,5-dicarboxylic acid. Considering the synthesizability of the metal-organic framework material, the raw material cost, and the ease of exchange of the modified ligand, preferably, the organic ligand includes at least one of fumaric acid, isophthalic acid, succinic acid, trans-cyclohexanedicarboxylic acid, dihydroxyfumaric acid, diamino fumaric acid, malic acid, aspartic acid, benzoquinone, furandicarboxylic acid, pyrazole-3,5-dicarboxylic acid. More preferably, the organic ligand includes at least one of fumaric acid, isophthalic acid, succinic acid, malic acid, aspartic acid, benzoquinone, and furandicarboxylic acid.

[0020] Optionally, in step (2), the modified ligand includes HCOO - , CO3 2- , CH3COO - , C2O4 2- , S2O3 2- , PO4 3- , F - , PF6 - , BF4 - , TiF6 2- and SiF6 2- at least one of them. Considering the cost of the raw materials of the modified ligand, the ease of exchange of the modified ligand, and the degree of damage to the structure of the organic framework material during the exchange process, preferably, the modified ligand includes HCOO - , CO3 2- , C2O4 2- , PF6- , BF4 - , TiF6 2- and SiF6 2- at least one of; Preferably, the modified ligand includes at least one of formic acid, acetic acid, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, oxalic acid, ammonium oxalate, ammonium hexafluorophosphate, ammonium tetrafluoroborate, ammonium hexafluorotitanate and ammonium hexafluorosilicate; More preferably, the modified ligand includes HCOO - , CO3 2- , C2O4 2- , BF4 - and SiF6 2- .

[0021] Optionally, in step (1), the solvent I includes at least one of water, DMF, methanol, ethanol, isopropanol, cyclohexane, hexane, cyclopentane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl propionate, ethyl propionate, butyl propionate, methyl ether, ethyl ether, γ-butyrolactone and γ-valerolactone. Considering the cost and performance of the solvent comprehensively, preferably, in step (1), the solvent I includes at least one of water, methanol, ethanol, cyclohexane, hexane, cyclopentane, butyl acetate, ethyl acetate, methyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, γ-butyrolactone and γ-valerolactone; For green synthesis, more preferably, the solvent I is water, or a mixture of water and water-soluble organic solvents; Most preferably, the solvent I is water.

[0022] Optionally, in step (1), the deprotonating base includes at least one of triethylamine, pyridine, piperidine, piperazine, pyrrolidine, morpholine, trimethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide and potassium hydroxide.

[0023] Optionally, in step (1), the aluminum source includes at least one of aluminum sulfate, aluminum trichloride, triethylaluminum, triisobutylaluminum, aluminum dimethanoate, and aluminum acetate. Preferably, the aluminum source includes at least one of aluminum sulfate, aluminum trichloride, triisobutylaluminum, and aluminum dimethanoate.

[0024] Optionally, in step (2), the solvent II includes at least one of water, DMF, formic acid, acetic acid, trifluoroacetic acid, methanol, ethanol, isopropanol, cyclohexane, hexane, cyclopentane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl propionate, ethyl propionate, butyl propionate, γ-butyrolactone, γ-valerolactone, acetonitrile, petroleum ether, benzene, toluene, xylene, acetone, and diethyl ether. To improve the modified ligand ratio and reduce the destructiveness of the modification loading process, preferably, the solvent II includes at least one of water, DMF, formic acid, acetic acid, trifluoroacetic acid, methanol, ethanol, cyclohexane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, γ-butyrolactone, γ-valerolactone, acetonitrile, xylene, acetone, and diethyl ether; considering the solvent cost and the greenness of the modification process, more preferably, the solvent II includes at least one of formic acid, acetic acid, methanol, ethanol, cyclohexane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, γ-butyrolactone, and γ-valerolactone.

[0025] The present invention also discloses an aluminum-based metal-organic framework material prepared by the preparation method as described above. The aluminum-based metal-organic framework material is composed of aluminum metal nodes, organic ligands, and modified ligands; the specific surface area of the aluminum-based metal-organic framework material is 200 m 2 / g to 1000 m 2 / g, and the average pore diameter is 0.3 nm to 1 nm.

[0026] Optionally, the specific surface area of the aluminum-based metal-organic framework material is preferably 200 m 2 / g to 800 m 2 / g, and more preferably 200 m 2 / g to 600 m 2 / g.

[0027] Optionally, the average pore diameter of the aluminum-based metal-organic framework material is preferably 0.3 nm to 0.8 nm. If the pore diameter is too small, it will lead to inability to adsorb or difficulty in desorption after adsorption. If the pore diameter is too large, it will lead to a decrease in the interaction force between gas molecules and the aluminum-based metal-organic framework material, resulting in a decline in adsorption performance.

[0028] The present invention also discloses an application of an aluminum-based metal-organic framework material prepared by the preparation method as described above, or an aluminum-based metal-organic framework material as described above in the adsorption and / or capture of carbon dioxide.

[0029] Optionally, at normal temperature and pressure, the aluminum-based metal-organic framework material has a carbon dioxide adsorption capacity of 4 mmol / g to 8 mmol / g, preferably 5 mmol / g to 7 mmol / g, more preferably 5 mmol / g to 6 mmol / g, a carbon dioxide selectivity for nitrogen of 15 to 400, preferably 50 to 400, more preferably 50 to 200, and a CO2 adsorption heat of 20 kJ / mol to 50 kJ / mol, preferably 20 kJ / mol to 40 kJ / mol.

[0030] Specifically, compared with single-ligand metal-organic frameworks, the aluminum-based metal-organic framework material of the present invention has better adsorption performance, relatively low adsorption heat, good regeneration ability and low regeneration energy consumption.

[0031] Optionally, it is applicable to the CO2 capture process in large-scale carbon emission sites such as coal power plants, cement plants and petrochemical plants in industrial production and in living places.

[0032] Implementing the embodiments of the present invention will have the following beneficial effects:

[0033] (1) The aluminum-based metal-organic framework material provided by the present invention has a suitable microporous structure, a large specific surface area, low regeneration energy consumption, easily available raw materials, a simple preparation process and relatively mild reaction conditions. At normal temperature and pressure, the carbon dioxide adsorption capacity is between 5 mmol / g and 8 mmol / g, and the CO2 / N2 separation selectivity is between 15 and 400. It has good carbon capture and separation ability and can be widely used in the adsorption and separation process of CO2 in various scenarios.

[0034] (2) The preparation method of the aluminum-based metal-organic framework material provided by the present invention adopts a combined preparation method of hydrothermal synthesis and solvent-assisted ligand loading modification. Its preparation conditions are mild, the operating conditions are simple, and the production cost is low, which is conducive to large-scale batch production.

[0035] (3) The aluminum-based metal-organic framework material provided by the present invention has good regeneration ability and low regeneration energy consumption, greatly saving the use cost. Description of the Drawings

[0036] Figure 1 It is the XRD spectrum of the metal-organic frameworks in Examples 1-2 and Comparative Examples 1-2 of the present invention. Detailed Embodiments

[0037] The following further illustrates the present invention with specific embodiments, but does not limit the present invention in any way.

[0038] Characterization method:

[0039] Measurement of specific surface area and pore parameters: The specific surface area and pore parameters were measured using a Quantachrome Autosorb-iQ2. The specific surface area and pore parameters of the prepared dual-ligand metal-organic framework were calculated from the Ar adsorption isotherm at 87 K, with an adsorption pressure of 0 - 760 mmHg and a sample test amount of 30 - 50 mg. Before testing, the sample was activated under high vacuum (<10 -6 Pa) at a temperature of 90 - 180 °C for more than 6 h.

[0040] Gas adsorption measurement and adsorption heat calculation: Static adsorption tests were carried out using a Quantachrome Autosorb-iQ2. The test gases were CO2 and N2, and their adsorption isotherms were measured at 278 K, 298 K, and 308 K, with an adsorption pressure of 0 - 1 bar and a sample test amount of 300 - 1000 mg. Before testing, the sample was activated under high vacuum (<10 -6 Pa) at a temperature of 90 - 180 °C for more than 6 h. The adsorption heat was calculated using the Clausius-Clapeyron equation from the adsorption isotherm data at three temperatures.

[0041] Determination of crystal phase structure: The phase structure was determined using a DX-2800 high-resolution X-ray diffractometer from Dandong Haoyuan Instruments. The detection light source was Cu Kα The tube current was 40 mA, the tube voltage was 40 kV, the step size was 0.02°, and the detection angle range was 5 - 40°.

[0042] Selectivity calculation: First, the adsorption isotherms of CO2 and N2 gases were fitted using the Langmuir Freundlich (L-F) model. The formula is q = q max bp n / (1 + bp n ), where q is the gas adsorption amount, q max is the maximum adsorption amount at the corresponding temperature, and b and n are constants. Then, the Henry coefficient was calculated using Henry's law. The formula is k = q max ×b. Finally, the ratio of the Henry coefficient k CO2 of CO2 to the Henry coefficient k N2 of N2 is the selectivity of the material. The formula is

[0043] Example 1

[0044] (1) Dissolve 2.24 g of fumaric acid in 40 mL of deionized water at room temperature. After stirring well, add 1.53 g of sodium hydroxide to form a mixed solution A; dissolve 9.28 g of AlCl3·6H2O in 40 mL of deionized water to form a mixed solution B; after fully mixing and stirring the mixed solutions A and B, pour them into a reaction kettle lined with polytetrafluoroethylene and react at 150 °C for 36 h. After filtration, the precursor MOF is obtained.

[0045] (2) Take 2 g of the precursor MOF and dissolve it in 50 mL of deionized water. Add 2.3 g of formic acid during stirring. After stirring well, pour it into a reaction kettle lined with polytetrafluoroethylene and react at 150 °C for 24 h. After the reaction, a white precipitate is obtained. Wash the precipitate obtained from the reaction with methanol and place it in a vacuum drying oven to dry at 100 °C for 12 h to obtain the dual-ligand metal-organic framework powder, labeled as MOF-1.

[0046] The adsorption performance of the above samples was tested. Before the adsorption test, the samples were activated under high vacuum (<10 -6 Pa) at a temperature of 100 °C for 6 hours. The specific surface area was calculated from the Ar adsorption isotherm at 87 K, and the specific surface area was 630 m 2 / g. The CO2 adsorption amount was measured to be 5.02 mmol / g at 298 K and 1 bar, the N2 adsorption amount was 0.31 mmol / g, the CO2 adsorption heat was 32.72 kJ / mol, the N2 adsorption heat was 16.94 kJ / mol, and the Henry selectivity of CO2 / N2 was 101.25.

[0047] Example 2

[0048] (1) Dissolve 1.84 g of isophthalic acid in 8 mL of DMF at room temperature. After stirring well, add 2.49 g of potassium hydroxide to form a mixed solution A; dissolve 8.44 g of Al(NO3)3·9H2O in 8 mL of DMF to form a mixed solution B; after fully mixing and stirring the mixed solutions A and B, pour them into a reaction kettle lined with polytetrafluoroethylene and react at 160 °C for 48 h. After filtration, the precursor MOF is obtained.

[0049] (2) Take 2 g of the precursor MOF and dissolve it in 60 mL of deionized water. Add 0.293 g of 5-methylisophthalic acid during stirring. After stirring well, pour it into a reaction kettle lined with polytetrafluoroethylene and react at 160 °C for 12 h. After the reaction, a white precipitate is obtained. Wash the precipitate obtained from the reaction with methanol and place it in a vacuum drying oven to dry at 160 °C for 12 h to obtain the dual-ligand metal-organic framework powder, labeled as MOF-2.

[0050] The adsorption performance of the above samples was tested. Before the adsorption test, the samples were under high vacuum (<10-6 Activated for 6 hours under condition of Pa). The specific surface area was calculated from the Ar adsorption isotherm at 87K, and the specific surface area was 567 m 2 / g. The CO2 adsorption amount was measured to be 4.03 mmol / g, the N2 adsorption amount was 0.27 mmol / g, the CO2 adsorption heat was 27.08 kJ / mol, the N2 adsorption heat was 17.28 kJ / mol, and the Henry selectivity of CO2 / N2 was 75.33 at 298K and 1 bar.

[0051] Example 3

[0052] (1) Dissolve 2.24 g of succinic acid in 40 mL of deionized water at room temperature. After stirring well, add 1.53 g of sodium hydroxide to form a mixed solution A; dissolve 14.42 g of Al(NO3)3·9H2O in 40 mL of deionized water; mix the mixed solutions A and B well and stir, then pour them into a reaction kettle with a polytetrafluoroethylene liner and react at 150 °C for 36 h. After filtration, the precursor MOF was obtained.

[0053] (2) Take 2 g of the precursor MOF and dissolve it in 50 mL of deionized water. Add 2.3 g of formic acid during stirring. After stirring well, pour it into a reaction kettle with a polytetrafluoroethylene liner and react at 150 °C for 24 h. After the reaction, a white precipitate was obtained. Wash the precipitate obtained from the reaction with methanol and place it in a vacuum drying oven to dry at 100 °C for 12 h to obtain the dual-ligand metal-organic framework powder, labeled as MOF-3.

[0054] The adsorption performance of the above samples was tested. Before the adsorption test, the samples were activated under high vacuum (<10 -6 Pa) at a temperature of 100 °C for 6 hours. The specific surface area was calculated from the Ar adsorption isotherm at 87K, and the specific surface area was 497 m 2 / g. The CO2 adsorption amount was measured to be 3.96 mmol / g, the N2 adsorption amount was 0.24 mmol / g, the CO2 adsorption heat was 30.51 kJ / mol, the N2 adsorption heat was 15.47 kJ / mol, and the Henry selectivity of CO2 / N2 was 61.76 at 298K and 1 bar.

[0055] Examples 4 - 6

[0056] Compared with Example 1, Examples 4 - 6 are different in that the crystallization temperature in step (1) is changed. Except for the above differences, other operations are the same and will not be elaborated here. The crystallization temperatures in Examples 4 - 8 correspond to 50 °C, 100 °C, and 200 °C respectively. MOF-4, MOF-5, and MOF-6 were prepared respectively according to the method of Example 1.

[0057] Examples 7 - 9

[0058] Compared with Example 1, Examples 9 - 14 are different in that the crystallization time in step (1) is changed. Except for the above differences, other operations are the same and will not be elaborated here. The crystallization temperatures in Examples 9 - 14 correspond to 12h, 24h, and 72h respectively. MOF - 7, MOF - 8, and MOF - 9 are prepared respectively according to the method of Example 1.

[0059] Examples 10 - 12

[0060] Compared with Example 1, Examples 10 - 12 are different in that the modification temperature in step (2) is changed. Except for the above differences, other operations are the same and will not be elaborated here. The modification temperatures in Examples 10 - 12 correspond to 50°C, 100°C, and 200°C respectively. MOF - 10, MOF - 11, and MOF - 12 are prepared respectively according to the method of Example 1.

[0061] Examples 13 - 15

[0062] Compared with Example 1, Examples 13 - 15 are different in that the modification time in step (2) is changed. Except for the above differences, other operations are the same and will not be elaborated here. The modification times in Examples 13 - 15 correspond to 2h, 48h, and 72h respectively. MOF - 13, MOF - 14, and MOF - 15 are prepared respectively according to the method of Example 1.

[0063] Examples 16 - 18

[0064] Compared with Example 1, Examples 16 - 18 are different in that the molar ratios of the organic ligand, aluminum source (calculated as Al 3+ ), and deprotonated base (calculated as the number of bound H protons) in step (1) are changed. The mass of the organic ligand remains unchanged. Except for the above differences, other operations are the same and will not be elaborated here. The molar ratios of the organic ligand, aluminum source (calculated as Al 3+ ), and deprotonated base (calculated as the number of bound H protons) in Examples 16 - 18 correspond to 1:2:2.1, 1:2.2:2, and 1:2.4:2 respectively. MOF - 16, MOF - 17, and MOF - 18 are prepared respectively according to the method of Example 1.

[0065] Examples 19 - 21

[0066] Compared with Example 1, Examples 19 - 21 are different in that the total addition amount of Solvent I is changed. Except for the above differences, other operations are the same and will not be elaborated here. The total addition amounts of Solvent I in Examples 22 - 24 are respectively the organic ligand and aluminum source (calculated as Al 3+According to the method of Example 1, MOF-19, MOF-20 and MOF-21 were prepared respectively.

[0067] Examples 22-24

[0068] Compared with Example 1, the difference between Examples 22-24 is that the amount of modified ligand added is changed. Except for the above differences, other operations are the same and will not be repeated here. The amount of modified ligand added in Examples 22-24 is 0.05 times, 2 times, and 5 times the molar number of organic ligand in the metal organic framework material precursor, respectively. MOF-22, MOF-23, and MOF-24 are prepared respectively according to the method of Example 1.

[0069] Examples 25-27

[0070] Compared with Example 1, Examples 25-27 differ in that the total amount of solvent II added is changed. Except for the above differences, other operations are the same and will not be repeated here. The total amount of solvent II added in Examples 25-27 is 10 times, 20 times, and 30 times the total mass of the metal organic framework material precursor, respectively. MOF-25, MOF-26, and MOF-27 are prepared respectively according to the method of Example 1.

[0071] Comparative Example 1

[0072] 2.24 g of fumaric acid and 4.21 g of AlCl3·6H2O were dissolved in 100 mL of DMF, stirred thoroughly, poured into a polytetrafluoroethylene-lined reactor and reacted at 130°C for 24 h. The precipitate obtained by the reaction was washed with acetone and methanol, and dried in a vacuum drying oven at 160°C for 12 h to obtain a single-ligand metal organic framework powder, which was labeled as MOF-1-Fu.

[0073] The above samples were subjected to adsorption performance test. Before the adsorption test, the samples were placed in a high vacuum (<10 -6 The specific surface area was calculated from the Ar adsorption isotherm at 87K and the specific surface area was 983 m 2 / g. At 298K and 1bar, the adsorption capacity of CO2 was 2.76mmol / g, the adsorption capacity of N2 was 0.34mmol / g, the adsorption heat of CO2 was 26.00kJ / mol, the adsorption heat of N2 was 18.91kJ / mol, and the Henry selectivity of CO2 / N2 was 19.04.

[0074] Comparative Example 2

[0075] 1.84 g of isophthalic acid and 8.44 g of Al(NO3)3·9H2O were dissolved in 20 mL of DMF. After stirring well, the solution was poured into a reaction kettle lined with polytetrafluoroethylene and reacted at 160 °C for 48 h. The precipitate obtained from the reaction was washed with acetone and methanol, and then placed in a vacuum drying oven and dried at 160 °C for 12 h to obtain a single-ligand metal-organic framework powder, labeled as MOF-2-mBDC.

[0076] The adsorption performance of the above sample was tested. Before the adsorption test, the sample was activated under high vacuum (<10 -6 Pa) at a temperature of 160 °C for 12 h. The specific surface area was calculated from the Ar adsorption isotherm at 87 K, and the specific surface area was 605 m 2 / g. At 298 K and 1 bar, the CO2 adsorption capacity was measured to be 2.53 mmol / g, the N2 adsorption capacity was 0.38 mmol / g, the CO2 adsorption heat was 25.92 kJ / mol, the N2 adsorption heat was 17.07 kJ / mol, and the Henry selectivity of CO2 / N2 was 17.85.

[0077] Table 1 Material performance table

[0078]

[0079]

[0080] According to the results in Table 1, it can be seen that compared with the single-ligand metal-organic frameworks MOF-1-Fu and MOF-2-mBDC prepared in the comparative examples and the double-ligand metal-organic frameworks MOF-1 and MOF-2 prepared in the examples, the double-ligand metal-organic frameworks prepared in the present invention have better adsorption performance, and the adsorption heat does not increase significantly, which means lower regeneration energy consumption. At the same time, it can also be seen that the regulation of parameters significantly affects the adsorption performance and regeneration energy consumption. Therefore, the double-ligand metal-organic frameworks prepared in the present invention can better meet the CO2 capture requirements in industrial production and living places, as well as the potential requirements for other gas captures.

[0081] Figure 1 XRD spectra of the examples and comparative examples. By comparison, it can be seen that their characteristic peaks are different, which further shows that in the solvent-assisted ligand exchange step, a stable double-ligand metal-organic framework different from the precursor metal-organic framework is formed.

[0082] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing an aluminum-based metal organic framework material, characterized in that: The following steps are involved: (1) mixing an organic ligand and a solvent I at room temperature, wherein the organic ligand is a carboxyl-containing ligand, and then adding a deprotonated base to form a mixed solution A; dissolving an aluminum source in the solvent I at room temperature to form a mixed solution B; mixing the mixed solution A and the mixed solution B, crystallizing at 25° C. to 200° C. for 0.5 h to 72 h, cooling to room temperature, and filtering, washing and drying in sequence to obtain a metal organic framework material precursor; (2) The metal organic framework material precursor and solvent II are mixed, and then a modified ligand is added, wherein the modified ligand is a small molecule anion, and the resulting mixed solution is modified at 25°C to 200°C for 2h to 96h. After the reaction is completed, the mixture is filtered, washed and dried to obtain an aluminum-based metal organic framework material.

2. The preparation method according to claim 1, characterized in that: In step (1), the organic ligand and the aluminum source (in the form of Al 3+ The molar ratio of the deprotonated base (based on the number of bound H protons) is 1:(2-2.4):(2.0-2.1); In step (1), the total amount of the solvent I added is the organic ligand and the aluminum source (in the form of Al 3+ 2 to 250 times the total mass of the In step (2), the amount of the modified ligand added is 0.05 to 5 times the molar number of the organic ligand in the metal organic framework material precursor; In step (2), the total amount of the solvent II added is 5 to 40 times the total mass of the metal organic framework material precursor.

3. The preparation method according to claim 1, characterized in that: In step (1), the organic ligand comprises at least one of fumaric acid, malonic acid, isophthalic acid, succinic acid, phthalic acid, trans-cyclohexanedicarboxylic acid, dihydroxyfumaric acid, diaminofumaric acid, dihydroxymaleic acid, diaminomaleic acid, malic acid, aspartic acid, 5-methylisophthalic acid, benzoquinone, furandicarboxylic acid, pyrazole-3,5-dicarboxylic acid, and 1H-pyrrole-2,5-dicarboxylic acid; In step (2), the modified ligand includes HCOO - 、CO3 2- 、CH3COO - 、C2O4 2- 、S2O3 2- PO4 3- 、F - PF6 - 、BF4 - 、TiF6 2- With SiF6 2- At least one of .

4. The preparation method according to claim 3, characterized in that: In step (1), the organic ligand comprises at least one of fumaric acid, isophthalic acid, succinic acid, trans-cyclohexanedicarboxylic acid, dihydroxyfumaric acid, diaminofumaric acid, malic acid, aspartic acid, benzoquinone, furandicarboxylic acid, and pyrazole-3,5-dicarboxylic acid; In step (2), the modified ligand includes HCOO - 、CO3 2- 、C2O4 2- PF6 - 、BF4 - 、TiF6 2- With SiF6 2- At least one of .

5. The preparation method according to claim 3, characterized in that: In step (2), the modified ligand includes at least one of formic acid, acetic acid, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, oxalic acid, ammonium oxalate, ammonium hexafluorophosphate, ammonium tetrafluoroborate, ammonium hexafluorotitanate and ammonium hexafluorosilicate.

6. The preparation method according to claim 1, characterized in that: In step (1), the solvent I comprises at least one of water, DMF, methanol, ethanol, isopropanol, cyclohexane, hexane, cyclopentane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl propionate, ethyl propionate, butyl propionate, methyl ether, ethyl ether, gamma-butyrolactone and gamma-valerolactone; In step (1), the deprotonating base comprises at least one of triethylamine, pyridine, piperidine, piperazine, pyrrolidine, morpholine, trimethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide and potassium hydroxide; In step (1), the aluminum source includes at least one of aluminum sulfate, aluminum chloride, triethylaluminum, triisobutylaluminum, aluminum diformate, and aluminum acetate; In step (2), the solvent II includes at least one of water, DMF, formic acid, acetic acid, trifluoroacetic acid, methanol, ethanol, isopropanol, cyclohexane, hexane, cyclopentane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl propionate, ethyl propionate, butyl propionate, γ-butyrolactone, γ-valerolactone, acetonitrile, petroleum ether, benzene, toluene, xylene, acetone and ether.

7. The preparation method according to claim 6, characterized in that: In step (1), the solvent I comprises at least one of water, methanol, ethanol, cyclohexane, hexane, cyclopentane, butyl acetate, ethyl acetate, methyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, γ-butyrolactone and γ-valerolactone; In step (2), the solvent II includes at least one of water, DMF, formic acid, acetic acid, trifluoroacetic acid, methanol, ethanol, cyclohexane, butyl acetate, ethyl acetate, methyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate, γ-butyrolactone, γ-valerolactone, acetonitrile, xylene, acetone and ether.

8. An aluminum-based metal organic framework material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The aluminum-based metal organic framework material is composed of aluminum metal nodes, organic ligands and modified ligands; The specific surface area of ​​the aluminum-based metal organic framework material is 200 m 2 / g~1000m 2 / g, and the average pore size is 0.3nm~1nm.

9. Use of an aluminum-based metal organic framework material prepared by the preparation method according to any one of claims 1 to 7, or the aluminum-based metal organic framework material according to claim 8 in the adsorption and / or capture of carbon dioxide.

10. The use according to claim 9, characterized in that: The aluminum-based metal organic framework material has a carbon dioxide adsorption capacity of 4 mmol / g to 8 mmol / g at room temperature and pressure, a carbon dioxide to nitrogen selectivity of 15 to 400, and a CO2 adsorption heat of 20 kJ / mol to 50 kJ / mol.

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