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

Abstract

The invention provides an aluminum-based metal organic framework material and a preparation method and application thereof.The preparation method comprises the steps that aluminum salt is completely dissolved in an organic solvent, then an acid regulator is added and fully mixed, 4, 4 ', 4'-(phenyl-1, 3, 5-trioxo)-benzoic acid is added and fully dissolved, and a mixed solution is obtained; crystallizing the mixed solution, washing a crystallized product, removing the residual organic solvent in the crystallized product, and drying to obtain the aluminum-based metal organic framework material, wherein the acid regulator comprises acetic acid or oxalic acid. Compared with the existing aluminum-based metal organic framework material, the aluminum-based metal organic framework material provided by the invention has good product crystallinity, stability, purity and yield, and the adsorbability of the aluminum-based metal organic framework material to normal hexane is also greatly improved.

Description

Technical Field

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

[0002] The commonly used optimization separation scheme is component separation. At present, the adsorption separation technology using 5A molecular sieve as the mainstream adsorbent to separate naphtha components mainly faces the following problems: 1) 5A molecular sieve only adsorbs straight-chain alkanes, so it can separate straight-chain alkanes from branched alkanes, cycloalkanes, and aromatics, but normal alkane molecules usually only account for 25%-35% of naphtha components, which cannot meet the current steam cracking ethylene production requirements for raw materials; 2) Based on the current separation technology, the residual oil contains more monobranched alkanes, so the overall octane number is low. If the normal alkanes and monobranched alkanes are separated at the same time, the octane number of the residual oil will be greatly improved, and it can be directly used as a high-octane gasoline additive component.

[0003] MOFs are new inorganic-organic hybrid nanoporous crystalline materials, which are composed of metal clusters and organic ligands bonded by coordination bonds. Due to the diversity of metal ions and organic ligands, an infinite variety of MOFs materials can be synthesized in theory. Currently, more than 20,000 MOFs materials have been reported. The most notable feature of MOFs materials as adsorbents is the adjustability of their pore size / pore volume and the chemical properties inside the pores. By rationally regulating the pore structure and pore chemical properties of MOFs materials, MOFs materials have the potential to achieve greater adsorption capacity and higher adsorption selectivity than molecular sieves.

[0004] Therefore, providing a new type of aluminum-based metal organic framework material and its preparation method and application has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In order to solve the above-mentioned shortcomings and deficiencies, an object of the present invention is to provide a method for preparing an aluminum-based metal organic framework material.

[0006] Another object of the present invention is to provide an aluminum-based metal organic framework material, which is prepared by the above-mentioned method for preparing the aluminum-based metal organic framework material.

[0007] Another object of the present invention is to provide the use of the aluminum-based metal organic framework material described above in the adsorption of n-hexane contained in a hydrocarbon mixture. Compared with the existing aluminum-based metal organic framework material, the aluminum-based metal organic framework material prepared by the solvent thermal synthesis method of the present invention has good product crystallinity, stability, purity and yield, and its adsorption of n-hexane is also greatly improved.

[0008] In order to achieve the above objectives, on the one hand, the present invention provides a method for preparing an aluminum-based metal organic framework material, wherein the method for preparing the aluminum-based metal organic framework material comprises:

[0009] Firstly, the aluminum salt is completely dissolved in an organic solvent, then an acid regulator is added and mixed thoroughly, and then 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid (abbreviated as bttotb) is added as an organic ligand and fully dissolved to obtain a mixed solution;

[0010] Crystallizing the mixed solution, washing the crystallized product, removing the residual organic solvent therein, and drying to obtain the aluminum-based metal organic framework material;

[0011] Wherein, the acid regulator includes acetic acid or oxalic acid.

[0012] As a specific embodiment of the preparation method described above, the aluminum salt comprises Al(NO 3 ) 3 9H 2 O、Al 2 (SO 4 ) 3 18H 2 O and AlCl 3 6H 2 O, etc. or a combination of several thereof.

[0013] As a specific embodiment of the preparation method described above of the present invention, the organic solvent includes N,N-dimethylformamide (DMF) or N,N-diethylformamide (DEF) and the like.

[0014] As a specific embodiment of the preparation method described above of the present invention, the crystallization temperature is 120-170° C. and the time is 3-5 days.

[0015] As a specific embodiment of the preparation method described above of the present invention, the mass ratio of aluminum salt to 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is 0.8-3.2:1.

[0016] As a specific embodiment of the preparation method described above of the present invention, the mass ratio of oxalic acid to 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is 0.33-3.33:1, preferably 0.5-2:1, and the mass ratio of the volume of acetic acid to 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is 0.37-6:1, preferably 0.73-3:1, and the units of volume and mass are ml and g, respectively.

[0017] As a specific embodiment of the preparation method described above in the present invention, anhydrous methanol is used to wash the crystallized product.

[0018] As a specific embodiment of the preparation method described above, after washing, the washed crystallized product is immersed in anhydrous methanol to exchange out the organic solvent remaining in the pores of the crystallized product.

[0019] On the other hand, the present invention also provides an aluminum-based metal organic framework material, which is prepared by the above-mentioned method for preparing the aluminum-based metal organic framework material.

[0020] In yet another aspect, the present invention further provides use of the aluminum-based metal organic framework material described above in adsorbing n-hexane contained in a hydrocarbon mixture.

[0021] Compared with the prior art, the beneficial technical effects that can be achieved by the present invention include:

[0022] 1) The adsorption capacity of Al-bttotb synthesized using oxalic acid for n-hexane was significantly improved.

[0023] The n-hexane adsorption experiment was conducted on Al-bttotb synthesized by adding different types of acids to compare the effect of acid type on adsorption capacity. The adsorption capacity of n-hexane of Al-bttotb prepared by formic acid was between 129mg / g and 151mg / g. The maximum adsorption capacity of n-hexane of Al-bttotb prepared by acetic acid was only 127.5mg / g. No crystals were generated when solid acids such as citric acid were used for preparation.

[0024] The adsorption capacity of n-hexane of Al-bttotb synthesized by adding different amounts of oxalic acid can reach 180 mg / g, with an average of 182 mg / g. Compared with the industrially applied ZSM-5 molecular sieve, the saturated adsorption capacity of n-hexane was only 80.4 mg / g under the same conditions. The adsorption capacity of n-hexane of Al-bttotb provided by the present invention is 2.26 times that of ZSM-5 molecular sieve, and the optimized material shows excellent n-hexane adsorption performance.

[0025] 2) Al-bttotb synthesized using oxalic acid has less pressure during the synthesis process.

[0026] In the material synthesis and scale-up experiment, the inner lining is still made of stainless steel. When formic acid is used, it will corrode the inner wall of the kettle, produce a large amount of gas in the kettle, and the system pressure is high, which affects the further industrial scale-up of the material. When oxalic acid is used instead, the system pressure is normal pressure, and the pressure system is stable, and the synthesis process is gentler. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 These are the XRD patterns of six Al-bttotb products synthesized in Examples 1 to 6 of the present invention.

[0029] Figure 2 This is a comparison chart of the adsorption capacity of n-hexane by six Al-bttotb products synthesized in Examples 1 to 6 of the present invention.

[0030] Figure 3 These are the XRD diagrams of three Al-bttotb products synthesized using different aluminum salts in Examples 4 and 7-8 of the present invention.

[0031] Figure 4 This is a comparison chart of the n-hexane adsorption capacity of three Al-bttotb products synthesized using different aluminum salts in Example 4 and Example 7-Example 8 of the present invention.

[0032] Figure 5 These are XRD diagrams of four Al-bttotb products synthesized using different mass ratios of aluminum salt to ligand in Examples 4 and 9 to 11 of the present invention.

[0033] Figure 6 This is a comparison chart of the n-hexane adsorption capacity of four Al-bttotb products synthesized using different aluminum salt to ligand mass ratios in Examples 4 and 9 to 11 of the present invention.

[0034] Figure 7 These are the XRD diagrams of seven Al-bttotb products synthesized using different synthesis times in Example 4, Example 12-Example 13 and Comparative Examples 4-Comparative Examples 7 of the present invention.

[0035] Figure 8 This is a comparison chart of the n-hexane adsorption capacity of seven Al-bttotb products synthesized using different synthesis times in Example 4, Example 12-Example 13 and Comparative Examples 4-Comparative Examples 7 of the present invention.

[0036] Fig. 9 These are the XRD patterns of four Al-bttotb products synthesized using different amounts of oxalic acid in Examples 4 and 14-16 of the present invention.

[0037] Fig.10This is a comparison chart of the n-hexane adsorption capacity of four Al-bttotb products synthesized using different amounts of oxalic acid in Example 4 and Example 14-Example 16 of the present invention.

[0038] Fig.11 These are the XRD patterns of four Al-bttotb products synthesized using different amounts of acetic acid in Examples 17 to 20 of the present invention.

[0039] Fig.12 This is a comparison chart of the n-hexane adsorption capacity of four Al-bttotb products synthesized using different amounts of acetic acid in Examples 17 to 20 of the present invention.

[0040] Fig.13 These are the XRD patterns of four Al-bttotb products synthesized using different amounts of formic acid in Comparative Example 8 to Example 11.

[0041] Fig.14 This is a comparison chart of the n-hexane adsorption capacity of four Al-bttotb products synthesized using different amounts of formic acid in Comparative Example 8 to Example 11. DETAILED DESCRIPTION

[0042] It should be noted that the term "comprises" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] "Scope" disclosed in the present invention is given in the form of lower limit and upper limit. It can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e. any lower limit can be combined with any upper limit to form a range. For example, for a specific parameter, a range of 60-120 and 80-110 is listed, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and the maximum range values ​​listed are 3, 4 and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.

[0044] In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in the present invention, and "0-5" is just an abbreviation of these numerical combinations.

[0045] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0046] In the present invention, unless otherwise specified, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0047] In the present invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the attached table, drawings and examples. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0049] In the embodiment of the present invention, the n-hexane adsorption capacity test of the Al-bttotb product includes the following specific steps:

[0050] Seal the lower end of the burette with quartz wool, pour Al-bttotb particles into the burette, and seal the upper end of the tube with a sealing film;

[0051] Add the required mass of raw oil into the sealed bottle, empty the flow pump, and after emptying, insert the raw material end of the flow pump into the sealed bottle, turn on the power, let the flow pump run for one circle to ensure that there is no other impurity contamination in the flow pump, and adjust it to an appropriate speed; insert the pump outlet end into the upper end of the burette for slow feeding, wait for the raw oil to penetrate the Al-bttotb particles and flow out of the tube mouth, and use a chromatographic bottle to collect the effluent; after the penetration is completed, recover the Al-bttotb material.

[0052] Adsorption characterization: The adsorption separation effect is judged by comparing the change in the content of n-hexane in the crude oil and the effluent collected in the breakthrough experiment using chromatographic analysis. The less n-hexane content in the effluent, the better the adsorption effect.

[0053] The reaction kettles used in the embodiments of the present invention are all hydrothermal synthesis reaction kettles with a volume of 25 ml.

[0054] Example 1

[0055] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0056] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0057] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0058] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0059] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 120° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0060] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0061] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0062] Example 2

[0063] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0064] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0065] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0066] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0067] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 130° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0068] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0069] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0070] Example 3

[0071] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0072] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0073] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0074] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0075] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 140° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0076] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0077] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0078] Example 4

[0079] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0080] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0081] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0082] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0083] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0084] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0085] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0086] Example 5

[0087] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0088] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0089] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0090] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0091] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 160° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0092] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0093] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0094] Example 6

[0095] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0096] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0097] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0098] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0099] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 170° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0100] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0101] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0102] Comparative Example 1

[0103] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0104] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0105] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0106] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0107] The mixed solution was put into a reactor, kept at a constant temperature of 100° C., and subjected to a crystallization reaction for 3 days. It was found that no aluminum-based metal organic framework material, i.e., Al-bttotb crystals were generated, and the product yield was 0.

[0108] Comparative Example 2

[0109] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0110] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0111] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0112] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0113] The mixed solution was charged into a reactor, kept at a constant temperature of 110° C., and subjected to crystallization reaction for 3 days. It was found that no aluminum-based metal organic framework material, i.e., Al-bttotb crystals were generated, and the product yield was 0.

[0114] Comparative Example 3

[0115] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0116] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0117] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0118] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0119] The mixed solution was charged into a reactor, kept at a constant temperature of 180° C., and subjected to a crystallization reaction for 3 days. It was found that no aluminum-based metal organic framework material, i.e., Al-bttotb crystals were generated, and the product yield was 0.

[0120] In the process of preparing Al-bttotb, it was found that: when the synthesis temperature was lower than 120°C, after the reaction, the reactor still contained a light yellow liquid, the same color as the solution before the reaction, and no obvious solid was generated. This may be because the reaction temperature was too low, resulting in the inability of the crystallization reaction to occur; and when the synthesis temperature was higher than 170°C, the liquid level in the reactor dropped significantly and no solid was generated. The liquid changed from the light yellow before the reaction to dark brown or even black, and a small amount of dark brown material was also attached to the reactor wall. By consulting the data, it was learned that the boiling point of the solvent DMF at normal pressure is 153°C. When the temperature is too high, it will gradually vaporize, and DMF can be decomposed into formic acid and dimethylamine under high temperature conditions. Therefore, this phenomenon may be caused by the reaction temperature being too high. DMF has been decomposed at this temperature, and Al(NO 3 ) 3 9H 2 O and the ligand cannot undergo further crystallization reaction. Within the synthesis temperature range of 120-170°C, the liquid in the kettle changes from light yellow before the reaction to brown after the reaction, and a large amount of white solid is generated at the bottom of the kettle, which is the product Al-bttotb.

[0121] The products synthesized at different temperatures were weighed, and the product yields corresponding to different synthesis temperatures were calculated. The product yield data of Examples 1 to 6 and Comparative Examples 1 to 3 synthesized under different temperature conditions are shown in Table 1 below.

[0122] Table 1 Yield / yield of Al-bttotb synthesized at different temperatures

[0123]

[0124] It can be found from Table 1 that the temperature range can be preferably set to 120-170°C according to the product yield. Furthermore, the product yield shows a trend of gradually increasing and then decreasing with the increase of the synthesis temperature. When synthesized at 160°C, the product yield increases to the highest, which is 54.12%. Then, when synthesized at 170°C, the yield decreases to 51.26%, which is lower than the yield of 53.85% synthesized at 150°C.

[0125] The products synthesized in Examples 1 to 6 were subjected to XRD analysis and compared with the spectra of the standard samples. The obtained XRD patterns are shown in Figure 1 As shown. Figure 1 It can be seen that the characteristic peak positions of the materials synthesized at 120-170℃ are consistent with those of the standard Al-bttotb samples, and the peak shapes are basically the same, without impurity peaks, proving that these samples have the same structural characteristics as the standard samples. This shows that Al-bttotb can be synthesized by this method within the temperature range of 120-170℃, and the diffraction peak intensity and crystallinity are the highest when synthesized at 150℃.

[0126] The six Al-bttotb products synthesized in Examples 1 to 6 were degassed and used for n-hexane adsorption test. The comparison of the adsorption amount of n-hexane by the Al-bttotb products synthesized in Examples 1 to 6 is shown in the figure below. Figure 2 As shown, from Figure 2 It can be found that under the same adsorption conditions, when the synthesis temperature is 120-150℃, the adsorption capacity of Al-bttotb for n-hexane is positively correlated with temperature, that is, the adsorption amount of Al-bttotb for n-hexane gradually increases with the increase of temperature, and then gradually decreases. At 150-170℃, the adsorption amount of Al-bttotb for n-hexane gradually weakens with the increase of temperature. The samples synthesized in the middle temperature range (130-160℃) have higher adsorption performance, and the n-hexane adsorption amount reaches more than 16g / 100g, which is expected; among them, the adsorption performance of the sample obtained at the synthesis temperature of 150℃ is the best, which is 18.37g / 100g. To sum up, the synthesis reaction of Al-bttotb is sensitive to temperature. When Al-bttotb is synthesized at a lower temperature, the degree of crystallization reaction will be relatively low, the product will be relatively small and the degree of crystallization will be relatively low. The defects of the Al-bttotb structure will directly lead to a decrease in the amount of n-hexane adsorption, so the yield and the amount of n-hexane adsorption are both small. When the synthesis temperature is too high, a small amount of DMF may decompose, which will destroy the progress of the crystallization reaction. Similarly, it will also lead to a decrease in the yield and the amount of n-hexane adsorption.

[0127] Example 7

[0128] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0129] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al 2 (SO 4 ) 3 18H 2 O was poured into 12.35 ml of DMF solution and a stirring magnet was added. 2 (SO 4 ) 3 18H 2 The dissolution rate of O is faster than that of Al(NO 3 ) 3 9H 2 O is too low, so it needs to be heated to completely dissolve, and a metal salt solution is obtained after stirring and dissolving completely;

[0130] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0131] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0132] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0133] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0134] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0135] Example 8

[0136] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0137] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g AlCl 3 6H 2O was poured into 12.35 ml of DMF and a stirring magnet was added. 3 6H 2 O is the most difficult to dissolve and needs to be ultrasonicated multiple times while heating to dissolve. After stirring and dissolving completely, a metal salt solution is obtained;

[0138] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0139] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0140] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0141] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0142] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0143] When aluminum salt and ligand undergo crystallization reaction, Al plays a leading role. 3+ and ligands, which are tightly bound to each other through Al-O bonds and continuously stretched and grown, eventually forming a unique structure of Al-bttotb. Examples 4 and 7-8 use the three most common aluminum salts, namely Al(NO 3 ) 3 9H 2 O、Al 2 (SO 4 ) 3 18H 2 O, and AlCl 3 6H 2 O is used as the raw material for synthesizing Al-bttotb. 3+ As a benchmark, the three salts can provide Al 3+ The amount of the substance is the same. The other synthesis conditions remain unchanged, and the synthesis temperature is selected to be 150°C for synthesis.

[0144] During the synthesis process, it was found that different aluminum salts had different solubility in DMF: Al(NO3 ) 3 9H 2 Compared with the other two aluminum salts, AlO can be dissolved in DMF in a shorter time to form a colorless and transparent solution when stirred at the same speed; 2 (SO 4 ) 3 18H 2 O dissolves at a relatively low rate and requires additional heating to completely dissolve under the same stirring conditions; while AlCl 3 6H 2 O is the most difficult to dissolve in DMF and needs to be dissolved in Al 2 (SO 4 ) 3 18H 2 O can be dissolved by simultaneous ultrasonic treatment. When the ligand is added to the three solutions, the speed at which the aluminum salt solution continues to dissolve the ligand also varies accordingly: the dissolution rate of the three aluminum salts is consistent with that of Al(NO 3 ) 3 9H 2 O solution, Al 2 (SO 4 ) 3 18H 2 O solution, AlCl 3 6H 2 O solution.

[0145] The products synthesized using different aluminum salts were weighed, and the product yields corresponding to the different aluminum salts were calculated. The product yield data of Example 4 and Example 7-Example 8 using different aluminum salts are shown in Table 2 below.

[0146] Table 2 Al-bttotb yield / yield of different aluminum salts

[0147]

[0148] It can be seen from Table 2 above that the use of Al(NO 3 ) 3 9H 2 O has the highest yield when synthesizing Al-bttotb, followed by Al 2 (SO 4 ) 3 18H 2 O, the lowest is AlCl 3 6H 2 O, which may be related to the difference in the solubility of different aluminum salts during synthesis.

[0149] XRD analysis was performed on the products synthesized using different aluminum salts in Example 4 and Example 7-Example 8, and compared with the spectra of the standard sample. The obtained XRD patterns are as follows: Figure 3 As shown. Figure 3 It can be seen that the peak shapes of the products synthesized using different aluminum salts in Example 4 and Example 7-Example 8 are basically the same, and have the crystal structure of Al-bttotb. This proves that these three different aluminum salts can all synthesize Al-bttotb. However, Al(NO 3 ) 3 9H 2 The diffraction peak intensity of the O synthesis product is significantly higher than that of the Al 2 (SO 4 ) 3 18H 2 O and AlCl 3 6H 2 O synthesis product, which indicates that Al(NO 3 ) 3 9H 2 The Al-bttotb synthesized by O has higher crystal purity.

[0150] The three products synthesized with different aluminum salts in Example 4 and Example 7-Example 8 were degassed and used for n-hexane adsorption test. The n-hexane adsorption amount comparison chart of the three products synthesized with different aluminum salts in Example 4 and Example 7-Example 8 is as follows: Figure 4 As shown. Figure 4 It can be seen that under the same adsorption conditions, Al(NO 3 ) 3 9H 2 Al-bttotb synthesized with O as aluminum salt has the best adsorption effect, with an adsorption capacity of 18.28 g / 100 g (182.8 mg / g). 2 (SO 4 ) 3 18H 2 O synthesized product is 1.27 times that of AlCl 3 6H 2 O synthesized product is 1.46 times.

[0151] Based on the experimental phenomena during synthesis and the evaluation results of the products, among these three salts, Al(NO 3 ) 3 9H 2 O is more easily dissolved in DMF and can be dispersed more evenly in the solution, thereby combining with the ligand more fully and flexibly, which is conducive to the crystallization reaction and the orderly growth of crystals. The final product has the highest crystallinity and the best adsorption effect on n-hexane. Therefore, Al(NO3 ) 3 9H 2 O is the most suitable aluminum salt for the synthesis of Al-bttotb. The operation is simple and the product performance is optimal. 3 ) 3 9H 2 O is the aluminum salt in the following examples.

[0152] Example 9

[0153] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0154] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0155] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0156] Weigh 3.0 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0157] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0158] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0159] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0160] Example 10

[0161] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0162] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0163] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0164] Weigh 1.0 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0165] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0166] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0167] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0168] Embodiment 11

[0169] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0170] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0171] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0172] Weigh 0.75 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0173] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0174] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0175] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0176] In Examples 4 and 9-11, Al(NO 3 ) 3 9H 2 The mass of O (2.4 g) remains unchanged, the mass of the ligand is adjusted (in Examples 4 and 8-10, the masses of the ligand are 1.5 g, 3.0 g, 1.0 g and 0.75 g, respectively), and the ratio of the two is scaled to explore the differences in the synthesis of Al-bttotb with different ratios. 3 ) 3 9H 2 The mass ratio of O to the ligand was adjusted to 0.8:1, 2.4:1, and 3.2:1, i.e., 0.5 times, 1.5 times, and 2 times the mass ratio in Example 4, and the synthesis was carried out under the same conditions.

[0177] When the mass ratio of the two is 0.8:1, the mass of the ligand increases to twice the original (i.e., Example 4). Due to the excessive amount, it cannot be dissolved in the original solution, and a white paste is formed after sufficient stirring; when the mass ratio is 2.4:1 and 3.2:1, due to the decrease in the mass of the ligand, it can be quickly dissolved after being added to the mixed solution, and the solution becomes light yellow. The experimental phenomenon is the same as when the mass ratio is 1.6:1 (corresponding to Example 4).

[0178] The products synthesized using different mass ratios of aluminum salt to ligand were weighed, and the product yields corresponding to the different mass ratios of aluminum salt to ligand were calculated. The product yield data of Examples 4 and 9-11 using different mass ratios of aluminum salt to ligand are shown in Table 3 below.

[0179] Table 3 Yields of Al-bttotb synthesized with different mass ratios of aluminum salt to ligand

[0180]

[0181] It can be seen from Table 3 that Al(NO 3 ) 3 9H 2 The larger the mass ratio of O to ligand, that is, the smaller the amount of ligand, the lower the product yield, especially when the mass ratio of the two is twice the original ratio, the yield decreases most significantly. In other words, the product yield is similar to Al(NO 3 ) 3 9H 2 The mass ratio of O and the ligand is inversely related, that is, when the mass ratio of the two is twice the original ratio, the product yield is the lowest. Compared with when the mass ratio of the two is 0.5 times the original ratio, the yield decreases by 38%.

[0182] XRD analysis was performed on the products synthesized using different aluminum salt to ligand mass ratios in Examples 4 and 9-11, and compared with the spectra of the standard samples. The obtained XRD patterns are shown in Figure 5 As shown. Figure 5 It can be seen that the peak shapes of the samples obtained under the four ratios are consistent, indicating that Al-bttotb can be synthesized in four different ratios, but the diffraction peak of the Al-bttotb sample synthesized after the ligand is increased is slightly offset and the intensity is lower. It is worth noting that although the amount of ligand is too large to be completely dissolved in the solution when the mass ratio is 0.8:1, Al-bttotb can still be synthesized.

[0183] The four products synthesized with different aluminum salt to ligand mass ratios in Examples 4 and 9-11 were degassed and used for n-hexane adsorption test. The n-hexane adsorption amount comparison of the four products synthesized with different aluminum salt to ligand mass ratios in Examples 4 and 9-11 is shown in the figure below: Figure 6 As shown. Figure 6 It can be seen that under the same adsorption conditions, increasing or decreasing Al(NO 3 ) 3 9H 2 The mass ratio of O to ligand will lead to a significant decrease in the adsorption capacity of Al-bttotb. Considering the yield and adsorption performance, Al(NO 3 ) 3 9H 2 The synthesis was performed with an initial ratio of O to ligand, i.e., 1.6:1.

[0184] Example 12

[0185] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0186] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0187] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0188] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0189] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 4 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0190] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0191] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0192] Example 13

[0193] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0194] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0195] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0196] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0197] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 5 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0198] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0199] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0200] Comparative Example 4

[0201] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0202] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0203] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0204] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0205] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 1 day to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0206] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0207] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0208] Comparative Example 5

[0209] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0210] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0211] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0212] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0213] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 2 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0214] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0215] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0216] Comparative Example 6

[0217] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0218] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0219] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0220] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0221] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 6 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0222] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0223] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0224] Comparative Example 7

[0225] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0226] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0227] After stirring completely, weigh 1.5 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0228] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0229] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 7 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystals;

[0230] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0231] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0232] In Example 4, Example 12-Example 13 of the present invention and Comparative Examples 4-Comparative Examples 7, the synthesis time / crystallization time was 1d, 2d, 3d, 4d, 5d, 6d, and 7d, and the other conditions were unchanged, and the differences between the obtained products were investigated. The yields of the products obtained under different synthesis times are shown in Table 4.

[0233] Table 4 Yield of Al-bttotb synthesized at different crystallization times

[0234]

[0235] As shown in Table 4, with the increase of synthesis time, the yield of the product gradually increases. After the crystallization reaction is carried out for 3 days, the growth rate of the yield slows down. Specifically, when the crystallization time is 1d-2d, the product yield is too low, only 17.80% and 39.73%. When the synthesis time is extended from 2d to 3d, the yield increases to 53.67%, and then remains basically unchanged.

[0236] XRD analysis was performed on the products synthesized at different synthesis times in Example 4, Example 12-Example 13 and Comparative Examples 4-Comparative Examples 7, and the spectra were compared with those of the standard samples. The obtained XRD patterns are shown in FIG. Figure 7 As shown. Figure 7 It can be seen that Al-bttotb can be synthesized at all synthesis times, but the diffraction peak of the sample with a synthesis time of 1d is significantly weaker than that of other samples.

[0237] The seven products synthesized at different synthesis times in Example 4, Example 12-Example 13 and Comparative Examples 4-Comparative Example 7 were degassed and used for n-hexane adsorption test. The n-hexane adsorption amount comparison chart of the seven products synthesized at different synthesis times in Example 4, Example 12-Example 13 and Comparative Examples 4-Comparative Example 7 is as follows: Figure 8 As shown. Figure 8As can be seen from Table 4, under the same adsorption conditions, when the synthesis time is extended from 1d to 3d, the adsorption amount of the product on n-hexane gradually increases to 18.33g / 100g; from 3d to 5d, the adsorption amount always fluctuates slightly around 18g / 100g, basically unchanged; and after 5d, that is, 6d and 7d, the adsorption amount of n-hexane begins to gradually decrease. This shows that the crystallization reaction of Al-bttotb is completely completed at 3d. Generally speaking, the longer the synthesis time, that is, the crystallization reaction time, the more thorough the crystallization process, the more perfect the generated crystals, and the higher the theoretical adsorption amount of n-hexane. However, the crystallization reaction time should not be too long. For example, when the reaction time is longer than 5d, other side reactions may occur in the system, and a very small number of Al-bttotb crystals may be transformed into other impurity crystals with more stable structures, which will reduce the adsorption capacity of the product but still increase the yield. Therefore, the synthesis time of Al-bttotb should be 3d. Compared with the original synthesis scheme, Al-bttotb has achieved the same adsorption capacity at this time, but the synthesis time has been reduced by 40%. The synthesis efficiency has been significantly improved while the energy consumption has been greatly reduced.

[0238] Embodiment 14

[0239] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0240] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0241] After stirring, weigh 1.0 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0242] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0243] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0244] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0245] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0246] Embodiment 15

[0247] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0248] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O is poured into 12.35 ml of DMF solution, a stirring magnet is added, and the mixture is stirred at room temperature until it is completely dissolved to obtain a metal salt solution;

[0249] After stirring, weigh 2.0 g of oxalic acid solid, add 2.65 ml of DMF and perform ultrasonication until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution;

[0250] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0251] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0252] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0253] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0254] Example 16

[0255] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0256] The total amount of DMF added to the whole system was kept at 15 ml, and 2.4 g Al(NO 3 ) 3 9H 2 O was poured into 11.2 ml of DMF solution, and a stirring bar was added, and stirred at room temperature until it was completely dissolved to obtain a metal salt solution;

[0257] After stirring, weigh 2.5g of oxalic acid solid, add 3.8ml of DMF and ultrasonicate until the oxalic acid solid is completely dissolved to obtain an oxalic acid solution, and add the prepared oxalic acid solution to the metal salt solution to obtain a mixed solution; it should be noted that when the amount of oxalic acid added is increased to 2.5g, 2.65ml of DMF cannot completely dissolve it, and DMF needs to be increased to 3.8ml, so the amount of DMF required for the metal salt solution becomes 11.2ml;

[0258] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0259] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0260] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0261] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0262] In the synthesis process of MOF materials, a small amount of acid needs to be added to adjust the pH of the synthesis system, thereby inducing the crystallization reaction and slowing down the growth rate of the crystal nucleus. In addition to comparing the effects of different reaction conditions on the synthesis, the amount of acid added to the system also needs to be examined. When the amount of acid is too small, a white gel-like substance is easily obtained without a crystal structure; when too much acid is added to the synthesis system, a colorless solution may eventually be formed without solid product generation. When oxalic acid is added to synthesize Al-bttotb, oxalic acid is usually in solid form, so in Al(NO 3 ) 3 9H 2 When oxalic acid is added to the O solution, the oxalic acid must first be dissolved using DMF and ultrasound to prepare an oxalic acid solution. 3 ) 3 9H 2After the O solution and the oxalic acid solution are mixed, continue stirring to make them evenly mixed.

[0263] The products synthesized using different amounts of oxalic acid were weighed, and the product yields corresponding to different amounts of oxalic acid were calculated. The yield data of the products synthesized using different amounts of oxalic acid in Example 4 and Example 14-Example 16 are shown in Table 5 below.

[0264] Table 5 Yield of Al-bttotb synthesized with different oxalic acid addition amounts

[0265]

[0266] It can be seen from Table 5 that with the increase of oxalic acid addition, the yield of the product gradually decreases and the rate of decrease also increases. When the amount of oxalic acid added is too much, the yield of Al-bttotb will decrease significantly.

[0267] XRD analysis was performed on the products synthesized using different amounts of oxalic acid in Example 4 and Example 14-Example 16, and compared with the spectra of the standard sample. The obtained XRD patterns are shown in Fig. 9 As shown. Fig. 9 It can be seen that when the amount of oxalic acid is only 1.0g, the diffraction peak of the sample is very low, indicating that the sample obtained under this condition has a low crystallinity. When the added amount is 1.5g, the diffraction peak of the sample is the highest and the crystallinity is the highest.

[0268] The four products synthesized with different oxalic acid dosages in Example 4 and Example 14-Example 16 were degassed and used for n-hexane adsorption test. The n-hexane adsorption of the four products synthesized with different oxalic acid dosages in Example 4 and Example 14-Example 16 is compared as shown in the figure. Fig.10 As shown. Fig.10 As can be seen from Table 5, under the same adsorption conditions, the n-hexane adsorption of the samples synthesized by adding oxalic acid at various ratios can reach 18g / 100g. After the amount of oxalic acid added is 1.5g, the yield of the product decreases faster with the increase in the amount of oxalic acid added. When the addition amount is 2.5g, the yield is the lowest, which is similar to the trend of formic acid and acetic acid shown below. But at the same time, the adsorption performance increases with the increase in the amount of acid, and the adsorption amount of the product synthesized by the addition of oxalic acid in various proportions exceeds 180mg / g. When 2.5g of oxalic acid is added, its adsorption performance is the largest, but its yield decreases by 50%, that is, the adsorption performance is the highest when the amount of acid is 2.5g, but at this time the yield is much lower than that of the other addition amounts. Considering the yield, crystallinity and adsorption performance, 1.5g of oxalic acid can be selected for synthesis.

[0269] Embodiment 17

[0270] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0271] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0272] Measure 1.1 ml of acetic acid and add it to the aluminum salt solution (recorded as 0.5 times the initial added volume);

[0273] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0274] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0275] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0276] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0277] Embodiment 18

[0278] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0279] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0280] Measure 2.25 ml of acetic acid and add it to the aluminum salt solution (recorded as 1 times the initial added volume);

[0281] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0282] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0283] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0284] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0285] Embodiment 19

[0286] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0287] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0288] Measure 3.4 ml of acetic acid and add it to the aluminum salt solution (recorded as 1.5 times the initial added volume);

[0289] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0290] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0291] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0292] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0293] Embodiment 20

[0294] This embodiment provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0295] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0296] Measure 4.5 ml of acetic acid and add it to the aluminum salt solution (recorded as twice the initial added volume);

[0297] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0298] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0299] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0300] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0301] XRD analysis was performed on the four products synthesized using different amounts of acetic acid in Examples 17 to 20, and compared with the spectra of the standard sample. The obtained XRD patterns are shown in Fig.11 As shown. Fig.11 It can be seen that the XRD spectra of the four products are basically the same, but the products synthesized by adding less acetic acid (0.5 times and 1 times, corresponding to Example 17 and Example 18) have slightly aggregated diffraction peaks in the range of 5-7.5°, and the diffraction peak intensity is slightly low, while this phenomenon does not appear in the other Al-bttotb samples. After increasing the amount of acetic acid added, the phenomenon disappears.

[0302] The four products synthesized using different amounts of acetic acid in Examples 17 to 20 were weighed, and the product yields corresponding to the different amounts of acetic acid were calculated. The yield data of the four products synthesized using different amounts of acetic acid in Examples 17 to 20 are shown in Table 6 below.

[0303] Table 6 Yield of Al-bttotb synthesized with different acetic acid addition amounts

[0304]

[0305] As can be seen from Table 6, the yields of the four products synthesized using different amounts of acetic acid in Examples 17 to 20 first increased and then decreased with the increase in the amount of acid, and remained stable when the added amount was 1 times and 1.5 times (corresponding to Examples 18 and 19, respectively).

[0306] The four products synthesized with different acetic acid dosages in Examples 17 to 20 were degassed and used for n-hexane adsorption test. The n-hexane adsorption comparison of the four products synthesized with different acetic acid dosages in Examples 17 to 20 is shown in FIG. Fig.12 As shown. Fig.12 It can be seen that under the same adsorption conditions, the adsorption amount is positively correlated with the amount of acetic acid added. As the amount of acid increases, the adsorption amount increases accordingly, reaching a peak value when the ratio is 2 (Example 20), but it is only 127.5 mg / g, and the adsorption capacity is only about 70% of the formic acid synthetic product.

[0307] Comparative Example 8

[0308] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0309] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0310] Measure 1.1 ml of formic acid and add it to the aluminum salt solution (recorded as 0.5 times the initial added volume);

[0311] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0312] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0313] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0314] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0315] Comparative Example 9

[0316] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0317] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0318] Measure 2.25 ml of formic acid and add it to the aluminum salt solution (recorded as 1 times the initial added volume);

[0319] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0320] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0321] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0322] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0323] Comparative Example 10

[0324] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0325] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0326] Measure 3.4 ml of formic acid and add it to the aluminum salt solution (recorded as 1.5 times the initial added volume);

[0327] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0328] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0329] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0330] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0331] Comparative Example 11

[0332] This comparative example provides a method for preparing an aluminum-based metal organic framework material, wherein the preparation method comprises the following steps:

[0333] Weigh 2.4 g Al(NO 3 ) 3 9H 2 Pour O into 15 ml DMF, add a stirring magnet, and stir at room temperature until it is completely dissolved. After stirring and dissolving completely, an aluminum salt solution is obtained;

[0334] Measure 4.5 ml of formic acid and add it to the aluminum salt solution (recorded as twice the initial added volume);

[0335] Weigh 1.5 g of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid ligand, add it to the mixed solution obtained in the previous step while stirring, and stir for more than 30 minutes until it is fully dissolved to obtain a mixed solution;

[0336] The mixed solution is placed in a reaction kettle, maintained at a constant temperature of 150° C., and subjected to a crystallization reaction for 3 days to obtain an aluminum-based metal organic framework material, namely, Al-bttotb crystal;

[0337] The product after the crystallization reaction is collected by suction filtration, washed with anhydrous methanol and fully immersed in anhydrous methanol to exchange the solvent DMF remaining inside the pores of the material. After the exchange, it is fully dried at room temperature to obtain a fresh aluminum-based metal-organic framework material, namely, Al-bttotb product.

[0338] After the reaction is completed, the product yield is calculated, and then the product is subjected to XRD analysis and its n-hexane adsorption capacity is tested.

[0339] XRD analysis was performed on the four products synthesized with different formic acid dosages in Comparative Example 8 to Example 11, and compared with the spectra of the standard sample. The obtained XRD patterns are shown in Fig.13 As shown. Fig.13 It can be seen that Al-bttotb products were synthesized under the four ratios, but the diffraction peak of the sample in the range of 5-7.5° was slightly different from that of the other samples after the amount of formic acid was doubled (Comparative Example 11). When the amount of formic acid added was 1.5 times (Comparative Example 10), the diffraction peak of the product was higher and the crystallinity was better.

[0340] The four products synthesized with different formic acid dosages in Comparative Example 8 to Example 11 were degassed and used for n-hexane adsorption test. The n-hexane adsorption comparison of the four products synthesized with different formic acid dosages in Comparative Example 8 to Example 11 is shown in FIG. Fig.14 As shown. Fig.14 It can be seen that under the same adsorption conditions, the adsorption amount of n-hexane by the sample tends to gradually increase with the increase of formic acid addition and then decrease rapidly. When the amount of formic acid added is twice the initial amount (Comparative Example 11), the adsorption amount of the product is less than 13g / 100g, and the adsorption capacity is relatively low.

[0341] Comparative Example 12

[0342] This comparative example refers to Example 17-Example 20, and the only difference therefrom is that the acetic acid therein is replaced with an equal amount of phosphoric acid. During the experiment, it was found that no Al-bttotb crystals were synthesized under different phosphoric acid dosages.

[0343] Comparative Example 13

[0344] This comparative example refers to Example 4 and Example 14-Example 16, and the only difference therefrom is that the oxalic acid therein is replaced with an equal amount of citric acid. During the experiment, it was found that no Al-bttotb crystals were synthesized under different citric acid dosages.

[0345] Comparing the results of formic acid, acetic acid, oxalic acid, citric acid and phosphoric acid synthesis, it can be seen that only formic acid, acetic acid and oxalic acid can synthesize Al-bttotb crystals, wherein acetic acid is worse than formic acid, and formic acid is worse than oxalic acid. Neither citric acid nor phosphoric acid can synthesize Al-bttotb crystals. Oxalic acid, as a solid acid, is less volatile, and formic acid is more volatile, easily causing harm to human body and environment, and the volatilized formic acid vapor may also cause corrosion of some experimental devices, so oxalic acid was finally selected for the synthesis of Al-bttotb, and the addition amount was 1 times (i.e. the addition amount in Example 4).

[0346] The applicant further explains in detail the main differences between oxalic acid and the other four acids and the beneficial technical effects that can be achieved by selecting oxalic acid in the present invention:

[0347] 1. MOF (metal organic framework) is a porous crystalline material composed of metal ions and organic ligands. In the synthesis process of MOFs materials, the use of acid is crucial to the success of MOF synthesis. Generally speaking, the role of formic acid used in the prior art can be reflected in the following aspects:

[0348] 1) Adjust the pH value of the reaction system:

[0349] Formic acid can be used as an acidic regulator to control the pH value during the synthesis process to affect the reaction. For example, in the MOFs synthesis process, it is often necessary to control the pH value of the reaction system within a certain range in order to ensure the crystal structure and stability of the synthesized product.

[0350] 2) Promote the coordination reaction between metal ions and organic ligands:

[0351] Acids can react chemically with metal ions and some groups in organic ligands, thereby promoting the coordination reaction between them. For example, in the synthesis of aluminum-based MOFs, acids can react with the carboxyl groups in the bttotb ligands to promote their coordination reaction with aluminum ions, thereby forming MOFs materials.

[0352] 3) Structure directing agent:

[0353] In the synthesis of MOF, formic acid sometimes also acts as a structure-directing agent, helping to control the formation of pore structure and crystal growth. It may affect the crystal size, morphology and crystal quality of the synthesized MOF. Factors such as formic acid concentration, addition timing and reaction temperature may have an important impact on the quality of the final product.

[0354] Second, due to the importance of acid type to MOF synthesis, in terms of acid selectivity optimization, acetic acid, which has a similar monocarboxyl structure to formic acid, was first tried. However, according to the experimental results, the adsorption capacity of Al-bttotb synthesized using acetic acid for n-hexane was greatly weakened, which further illustrates the key influence of acid type on synthesis. When acetic acid replaces formic acid in the synthesis of Al-MOF, the weakened adsorption and separation effect on n-hexane may be caused by the following factors:

[0355] 1) Molecular size and steric hindrance:

[0356] Formic acid (HCOOH) is the smallest carboxylic acid, with only one carboxyl group and one hydrogen atom. Due to its smaller size, it may leave more space around the metal center, which helps to form larger pores, which are favorable for the adsorption of larger organic molecules such as n-hexane.

[0357] Acetic acid (CH 3 COOH) has a methyl group (CH 3 ), whose molecular volume is larger than that of formic acid, may cause steric hindrance and affect the size and shape of the pores in the MOF structure, thereby reducing the pore space available for n-hexane molecules to enter and adsorb.

[0358] 2) Coordination environment and coordination saturation of the metal center:

[0359] Due to its smaller molecular structure, formic acid may promote more open sites or different coordination geometric configurations of the metal center when forming metal coordination, thereby enhancing the adsorption capacity of n-hexane.

[0360] The methyl group of acetic acid may affect the coordination environment, reducing the coordination saturation of the metal center, thereby weakening the adsorption capacity of MOF for n-hexane.

[0361] 3) Influence of functional groups:

[0362] If acetic acid is not completely removed from the metal nodes during the synthesis process like formic acid, its acetate groups may occupy a certain space in the pores of the MOF, reducing the effective pore volume available for the adsorption of n-hexane.

[0363] 4) Acidity and hydrogen bonding ability:

[0364] Due to its higher acidity and hydrogen bonding ability, formic acid may help form a more ordered structure through hydrogen bonding during the self-assembly process of MOF, which is crucial for the formation of well-defined pore structures.

[0365] Acetic acid is weakly acidic, and although it can also form hydrogen bonds, the presence of its methyl group may interfere with the formation of hydrogen bonds, thereby affecting the order of the final structure.

[0366] Taking all the above factors into consideration, although acetic acid and formic acid are both carboxylic acids, their slight differences in the synthesis of Al-MOF may lead to significant changes in the pore structure and metal center environment, thereby affecting the adsorption and separation effect of the material on n-hexane.

[0367] 3. According to the experimental results of acetic acid, the larger the size of the acid used, the weaker the adsorption capacity. And the ligand contains carboxylic acid groups. If a polycarboxylic acid is used, it may also inhibit the coordination of metal ions and ligands due to competition. However, due to the complex coordination environment in MOF synthesis, efforts are still being made to explore and try dicarboxylic acid structure acids to determine whether they can form a more complex coordination structure with the metal center. It has a higher degree of cross-linking and a more complex pore network, thereby improving the adsorption performance. The experimental results show that the adsorption capacity of Al-bttotb synthesized using oxalic acid for n-hexane is greatly improved. Compared with formic acid and acetic acid, the advantages of oxalic acid are:

[0368] 1) Molecular structure:

[0369] Oxalic acid (H 2 C 2 O 4 ) is a dibasic acid containing two carboxylic acid groups, which makes it a multidentate ligand capable of forming stable multi-point coordination bonds with metal ions.

[0370] Formic acid (HCOOH) is the simplest carboxylic acid, with only one carboxylic acid group. It tends to form coordination bonds with metal ions as a monodentate ligand.

[0371] Acetic acid (CH 3 COOH) is also a monobasic acid, but due to its methyl group (CH 3 ), whose molecular volume is larger than that of formic acid, may lead to different spatial coordination effects.

[0372] 2) Acidity (pKa):

[0373] Oxalic acid is highly acidic (the first-step dissociation constant pKa1 is approximately 1.25) due to the interaction between its two carboxylic acid groups, which may affect the pH value in the synthesis and thus the formation of MOF.

[0374] With a pKa of approximately 3.75, formic acid is a weaker acid and has less impact on pH during synthesis.

[0375] Acetic acid has a pKa of about 4.76, making it the weakest acid of the three and having the weakest effect on pH adjustment during the synthesis process.

[0376] 3) Influence on pore structure and functionalization:

[0377] Oxalic acid, due to its multidentate coordination properties, may promote the formation of more functionalized pores and enhanced cross-linked structures. The pore properties of MOF are strongly affected by the directionality of the structure. Oxalic acid, as a bridging ligand, may cause the metal-organic framework to grow in different directions, forming a highly ordered pore structure, which has selective adsorption capacity for molecules of specific size and shape, that is, it shows higher adsorption capacity for molecules such as n-hexane.

[0378] The MOF synthesized by formic acid may have less cross-linking degree and different pore structure, which may lead to weaker adsorption capacity for n-hexane.

[0379] Due to its large molecular volume and weak acidity, acetic acid may form larger pores in the synthesized MOF, but it may also occupy too much pore space due to its large molecular volume, affecting the adsorption performance.

[0380] 4) Coordination environment of metal center:

[0381] Oxalic acid can form strong coordination bonds with metal centers, which helps to form a stable framework in MOF synthesis. Its multidentate coordination properties enable it to effectively bridge metal ions during crystal growth, forming a more uniform pore size and shape.

[0382] The coordination bonds between formic acid and metal centers are usually weak, which may lead to the unstable structure of the synthesized MOF, especially the structural collapse after the removal of the template or solvent.

[0383] The coordination strength of acetic acid with metals is similar to that of formic acid, which is relatively weak. It is generally not inclined to form bridging coordination in MOF synthesis, which may lead to a relatively weak metal-organic framework structure.

[0384] Taking all the above factors into consideration, when considering the chemical reactions for synthesizing MOFs, the dicarboxylic acid group and multidentate coordination properties of oxalic acid may be more effective than the monocarboxylic acid group of acetic acid in constructing a more stable, porous and suitable MOF structure for adsorbing small molecules. It is not just the molecular size itself, but also the geometric shape of the molecule, the position of the functional groups, and the intermolecular interactions that jointly determine its role in MOF synthesis and its impact on the final MOF properties. So even though the oxalic acid molecule itself is larger, because it can span multiple metal centers, it may lead to a more rigorous structure, which may be beneficial for molecular screening and adsorption.

[0385] Fourth, continue to explore acids with polyhydroxyl and polycarboxyl structures, such as phosphoric acid and citric acid, to determine whether the huge difference in adsorption performance is caused by the fact that oxalic acid has one more carboxyl group than acetic acid. The experimental results show that no crystals are generated in phosphoric acid and citric acid. Compared with oxalic acid, the differences among the three are:

[0386] 1) Molecular structure:

[0387] Oxalic acid is the simplest dicarboxylic acid, with two adjacent carboxyl groups that can serve as a planar bidentate ligand to form a stable five- or six-membered ring structure with metal ions, promoting uniform and orderly crystal growth. The two carboxyl groups of oxalic acid are spatially symmetrical, which means that they can form linear or angular structures when coordinated, helping to maintain the structural order and pore consistency of MOF.

[0388] Phosphoric acid is a medium-strength tribasic acid with one phosphorus atom and three hydroxyl (-OH) groups. In MOF synthesis, phosphoric acid often forms a stable phosphate radical (PO 4 3- ), this multi-core ligand may not be easy to form a suitable MOF structure due to its large size and more complex coordination mode. Phosphate is a triangular pyramid in space, which may cause steric hindrance when participating in the construction of MOF and is not conducive to the formation of an ordered crystal structure, especially when a more complex coordination geometry is required.

[0389] Citric acid contains three carboxylic acid groups and one hydroxyl group. It is a multifunctional organic acid that can provide multi-point coordination, but this may also lead to diverse and unpredictable coordination modes in MOF synthesis. This uncertainty may affect the orderly growth of crystals. The molecular structure of citric acid is large and flexible, and it may form complex ring structures or multiple coordination modes during the coordination process. This uncertainty and variability may lead to difficult-to-control crystal growth or interfere with orderly crystal stacking.

[0390] 2) Acidity (pKa):

[0391] Oxalic acid, as a strong organic acid, can effectively adjust the pH of the synthesis reaction, but due to its high acidity, it needs to be used with caution to avoid over-protonation.

[0392] Phosphoric acid is highly acidic and can cause the pH of the reaction system to be too low, which may be detrimental to the formation of MOF crystals.

[0393] Citric acid is also a strong acid, but due to its multiple functional groups, its acidity is affected by its internal functional group effects and may lead to multiple reaction pathways and side reactions.

[0394] Taking all the above factors into consideration, oxalic acid, due to its small and symmetrical structure, can form a stable and orderly coordination environment with metal ions, promoting the uniform growth of MOF crystals. However, phosphoric acid and citric acid, due to their larger molecular size, higher acidity and complex multi-dentate coordination properties, may cause crystal growth obstacles or the formation of disordered structures in MOF synthesis.

[0395] 5. When designing a synthetic strategy, choosing the right acid type is key. Ideally, there should be:

[0396] Moderate acidity, providing a suitable coordination environment, and rationality in spatial structure. Therefore, in MOF synthesis, not only the number of carboxylic acid groups, but also their spatial arrangement and the way they interact with metal ions jointly determine the applicability of the acid.

[0397] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the protection scope of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other and with each other, and with each other.

Claims

1. A method for preparing an aluminum-based metal organic framework material, characterized in that: The preparation method comprises: Firstly, the aluminum salt is completely dissolved in the organic solvent, then the acid regulator is added and mixed thoroughly, and then 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is added and dissolved thoroughly to obtain a mixed solution; Crystallizing the mixed solution, washing the crystallized product, removing the residual organic solvent therein, and drying to obtain the aluminum-based metal organic framework material; Wherein, the acid regulator includes acetic acid or oxalic acid.

2. The preparation method according to claim 1, characterized in that: The aluminum salt includes one or a combination of Al(NO3)3·9H2O, Al2(SO4)3·18H2O and AlCl3·6H2O.

3. The preparation method according to claim 1 or 2, characterized in that: The organic solvent includes N,N-dimethylformamide or N,N-diethylformamide.

4. The preparation method according to claim 1 or 2, characterized in that: The crystallization temperature is 120-170° C. and the crystallization time is 3-5 days.

5. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the aluminum salt to 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is 0.8-3.2:

1.

6. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the oxalic acid to 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is 0.33-3.33:1, the volume ratio of the acetic acid to the mass ratio of 4,4',4"-(phenyl-1,3,5-trioxo)-benzoic acid is 0.37-6:1, and the units of volume and mass are ml and g, respectively.

7. The preparation method according to claim 1 or 2, characterized in that: The crystallized product was washed with anhydrous methanol.

8. The preparation method according to claim 1 or 2, characterized in that: After washing, the washed crystallized product is immersed in anhydrous methanol to exchange the organic solvent remaining in the pores of the crystallized product.

9. An aluminum-based metal organic framework material, prepared by the method for preparing an aluminum-based metal organic framework material according to any one of claims 1 to 8.

10. Use of the aluminum-based metal organic framework material according to claim 9 in adsorbing n-hexane contained in a hydrocarbon mixture.

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