Synthesis method of MIL101

Abstract

The invention relates to the technical field of metal organic framework materials, in particular to a synthesis method of MIL101. The synthesis method comprises the following steps: weighing metal salt and disodium terephthalate, mixing, adding pure water, dispersing and uniformly mixing to obtain a first precursor solution; placing the first precursor solution in a spray dryer, setting the inlet temperature of the spray dryer to be 100-160 DEG C, carrying out first spray drying, and collecting to obtain a first MIL-101 crude product; respectively weighing the first MIL-101 crude product, metal salt and disodium terephthalate, mixing, adding the mixture into pure water, and uniformly dispersing and mixing to obtain a second precursor solution; placing the second precursor solution in a spray dryer, setting the inlet temperature of the spray dryer to be 120-180 DEG C, carrying out second spray drying, and collecting to obtain a second MIL-101 crude product; and washing, centrifuging, drying and grinding the second MIL-101 crude product to obtain an MIL-101 finished product. The synthesis method of the MIL101 solves the problems of long synthesis reaction time and low space time yield of the existing synthesis method of the MIL101.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal-organic framework materials, and particularly relates to a synthesis method of MIL101. BACKGROUND

[0002] MIL-101 is a classic metal-organic framework material, which is obtained by connecting trivalent metal ions (such as Cr 3+ , Al 3+ , Fe 3+ ) as metal nodes with carboxyl groups of terephthalic acid, and has a very high specific surface area, a large pore volume, and good chemical stability and hydrothermal stability.

[0003] The traditional synthesis method of MIL-101 is a hydrothermal synthesis method, which mixes terephthalic acid and metal salt in an aqueous solution, then adds a mineralizer (such as hydrofluoric acid, nitric acid, etc.), and reacts under high temperature and high pressure for a period of time to obtain MIL-101. For example, patent CN119680523A discloses a carbon capture material based on choline chloride and a preparation method thereof, wherein the synthesis process of MIL-101 is: mixing chromium nitrate nonahydrate, choline chloride, terephthalic acid and water, then adding 0.26 mL of 40% concentration hydrofluoric acid dropwise while stirring, and reacting at 220℃ for 8 hours. Patent CN119869493A discloses a MOFs adsorbent of cumene and a preparation method and application thereof, wherein the synthesis process of MIL-101 is: mixing terephthalic acid with chromium nitrate nonahydrate and deionized water, and reacting at 190℃ for 8 hours.

[0004] The hydrothermal synthesis method of the prior art has many shortcomings, for example: the high reaction temperature leads to high energy consumption, the one-time synthesis time of the process including heating, reaction, cooling and post-processing is long, and the space-time yield is low. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a synthesis method of MIL101 to at least solve the problems of long synthesis reaction time and low space-time yield of the prior art.

[0006] The following presents a summary of the disclosure in order to provide a basic understanding of some aspects. This summary is not an extensive overview of the disclosure and is not intended to identify key or critical elements or to delineate any limitations of the implementation or claims. Moreover, this summary provides a simplified outline of some aspects that can be described in further detail in other parts of the disclosure.

[0007] The present application solves the above technical problems by the following technical means:

[0008] The embodiment of the present application provides a synthesis method of MIL101, comprising the following steps:

[0009] The metal salt and the disodium terephthalate are weighed and mixed, pure water is added, ultrasonic dispersion is carried out, and a first precursor solution is obtained;

[0010] The first precursor solution is placed in a spray dryer, the inlet temperature of the spray dryer is set to 100-160 DEG C, first spray drying is carried out, and the first MIL-101 crude product is collected through a collector of the spray dryer;

[0011] The first MIL-101 crude product, the metal salt and the disodium terephthalate are weighed respectively, mixed, added into pure water, ultrasonic dispersion is carried out, and a second precursor solution is obtained;

[0012] The second precursor solution is placed in a spray dryer, the inlet temperature of the spray dryer is set to 120-180 DEG C, second spray drying is carried out, and the second MIL-101 crude product is collected through a collector of the spray dryer;

[0013] The second MIL-101 crude product is washed, centrifuged, dried and ground, and the MIL-101 finished product is obtained.

[0014] In some embodiments, the metal salt is selected from at least one of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, chromium nitrate nonahydrate and aluminum nitrate nonahydrate.

[0015] In some embodiments, in the preparation of the first precursor solution, the molar ratio of the metal salt to the disodium terephthalate is 1:(0.8-1.2).

[0016] In some embodiments, in the first spray drying, the feeding rate is set to 3-20 mL / min, and the flow rate is set to 50-200 mL / min.

[0017] In some embodiments, in the first spray drying, the feeding rate is set to 10 mL / min, the flow rate is set to 150 mL / min, and the inlet temperature is set to 120 DEG C.

[0018] In some embodiments, in the preparation of the second precursor solution, the molar ratio of the first MIL-101 crude product, the metal salt and the disodium terephthalate is (0.1-2):1:(0.8-1.2).

[0019] In some embodiments, in the second spray drying, the feeding rate is set to 3-20 mL / min, and the flow rate is set to 50-200 mL / min.

[0020] In some embodiments, the second spray drying is performed with a feed rate of 5 mL / min, a flow rate of 75 mL / min, and an inlet temperature of 160℃.

[0021] In some embodiments, the washing is performed with hot pure water at 30-40℃ for 1.5-3h.

[0022] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0023] The synthesis method of the MIL 101 provided by the present application has the following advantages: on the one hand, the spray drying method is used to synthesize MIL-101, which can quickly form MOFs, thereby improving the space-time yield of MIL-101. On the other hand, disodium terephthalate is used to replace terephthalic acid to synthesize MIL-101, which makes full use of the high solubility of disodium terephthalate in water, reduces the synthesis temperature of spray drying by more than 1 / 3, saves energy, and avoids the use of solvents such as DMF. More importantly, the traditional hydrothermal synthesis method needs to use a large amount of organic solvent for washing several times in the post-processing process, and the metal salt and the ligand used in the present application can be dissolved in water and can be directly washed with water, which not only protects the environment, but also greatly saves the washing time and cost of the post-processing link. In order to improve the performance of the product, the present application combines the principle of seed synthesis MOFs method to perform secondary spray drying on the synthesized MOFs, and uses the MIL-101 synthesized by the first spray drying as seeds. In the process of spray drying, the MIL-101 synthesized in the second time will grow on the surface of the MIL-101 synthesized in the first time, which can increase the particle size of the MOFs, increase the stability of the structure, and thus improve the performance of the product. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is an electron microscope image of the MIL-101 synthesized in Example 1;

[0025] Figure 2 is an electron microscope image of the MIL-101 synthesized in Example 2;

[0026] Figure 3 is an electron microscope image of the MIL-101 synthesized in Example 3;

[0027] Figure 4 is a nitrogen adsorption isotherm graph of the MIL-101 synthesized in Examples 1-3. DETAILED DESCRIPTION

[0028] Reference will now be made to example embodiments, examples of which are illustrated in the detailed description, figures and examples. It should be understood that other embodiments can be utilized and structural and functional changes can be made without departing from the scope of the present disclosure. Furthermore, features of various embodiments can be combined or altered without departing from the scope of the present disclosure. Accordingly, the following description is presented solely for purposes of illustration and should not be construed as limiting in any way the many alternatives and modifications that are encompassed by the embodiments shown and described. In this disclosure, numerous specific details are provided, to provide a thorough understanding of the present subject matter. It will be apparent, however, to one of ordinary skill in the art that the aspects of the present disclosure can be practiced without some or all of these specific details. In other instances, well known structures and functions have not been described in detail in order to avoid obscuring the concepts of the present subject matter.

[0029] As used herein, the expressions "instance" and "exemplary" mean an example or illustration. The expressions "instance" and "exemplary" do not indicate a key or preferred aspect or embodiment. The expression "or" is intended to be inclusive, unless otherwise indicated.

[0030] The following problems occur when MIL-101 is synthesized using only a spray drying method: the N,N-dimethylformamide (DMF) solution needs to be evaporated in a short time, and the temperature of hot air drying needs to reach 180-220°C. This not only requires a large amount of energy, but the emission of DMF vapor also has a great impact on human health and the environment. On the other hand, incompletely dissolved terephthalic acid can affect the coordination of metal salts and ligands, inhibit the growth of MIL-101 small crystals into large crystals, and result in a large number of impurities in the synthesized MIL-101 and uneven pore size distribution. In addition, the short contact time of spray drying results in small particle size of the synthesized MOF, poor structural stability, and affects the performance of the product.

[0031] Therefore, a method for synthesizing MIL-101 is provided, which uses disodium terephthalate instead of terephthalic acid to synthesize MIL-101, fully utilizes the high solubility of disodium terephthalate in water, reduces the synthesis temperature of spray drying by more than 1 / 3, saves energy, and avoids the use of solvents such as DMF. More importantly, the traditional hydrothermal synthesis method requires multiple washings with a large amount of organic solvent during the post-processing process, the metal salt and ligand used in the present application are both soluble in water and can be directly washed with water, which greatly saves the washing time and cost of the post-processing link while protecting the environment. In order to improve the performance of the product, the principle of seed synthesis MOFs is combined to perform secondary spray drying of the synthesized MOFs. The first synthesized MIL-101 is used as a seed, and the second synthesized MIL-101 grows on the surface of the first synthesized MIL-101 during the spray drying process. This can increase the particle size of the MOFs, increase the structural stability, and thus improve the performance of the product.

[0032] Specifically, the synthesis method of the MIL 101 according to the present application comprises the following steps:

[0033] (1) Preparation of the first precursor solution

[0034] The metal salt and the disodium terephthalate are weighed and mixed, pure water is added, and ultrasonic dispersion is performed for 5-90 min to obtain the first precursor solution.

[0035] In this step, the metal salt is selected from at least one of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, chromium nitrate nonahydrate, and aluminum nitrate nonahydrate, the molar ratio of the metal salt to the disodium terephthalate is 1:(0.8-1.2), and 5 L of pure water is used per mole of the metal salt.

[0036] (2) First spray drying

[0037] The first precursor solution is transferred into a spray dryer, the feed rate of the spray dryer is set to 3-20 mL / min, the flow rate is set to 50-200 mL / min, the inlet temperature is set to 100-160°C, the first spray drying is performed, and the first MIL-101 crude product is collected through the collector of the spray dryer.

[0038] (3) Preparation of the second precursor solution

[0039] The first MIL-101 crude product, the metal salt, and the disodium terephthalate are weighed and mixed, respectively, pure water is added, ultrasonic dispersion is performed for 10-120 min to mix, and the second precursor solution is obtained.

[0040] In this step, the molar ratio of the first MIL-101 crude product, the metal salt, and the disodium terephthalate is (0.1-2):1:(0.8-1.2), where the molar amount of the first MIL-101 crude product is calculated according to the pure MIL-101. The metal salt is selected from at least one of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, chromium nitrate nonahydrate, and aluminum nitrate nonahydrate, and 10 L of pure water is used per mole of the metal salt.

[0041] (4) Second spray drying

[0042] The second precursor solution is placed in a spray dryer, the feed rate of the spray dryer is set to 3-20 mL / min, the flow rate is set to 50-200 mL / min, the inlet temperature is set to 120-180°C, the second spray drying is performed, and the second MIL-101 crude product is collected through the collector of the spray dryer.

[0043] (5) Post-treatment

[0044] The second MIL-101 crude product is washed with hot pure water at 30-40℃ for 1.5-3h, centrifuged, dried, and ground to obtain the MIL-101 finished product.

[0045] The synthesis method of the MIL-101 of the present application will be described in detail below through Examples 1-5:

[0046] Example 1

[0047] The synthesis method of the MIL-101 of the present application will be described in detail below through Examples 1-5:

[0048] (1) Preparation of the first precursor solution

[0049] 400g of chromium nitrate nonahydrate and 210.9g of disodium terephthalate are weighed and mixed, 5L of pure water is added, and ultrasonic dispersion is performed for 30min to obtain the first precursor solution.

[0050] (2) First spray drying

[0051] The first precursor solution is transferred into a spray dryer, the feed rate of the spray dryer is set to 10 mL / min, the flow rate is set to 150 mL / min, and the inlet temperature is set to 120℃, and the first spray drying is performed, and the first MIL-101 crude product is collected through the collector of the spray dryer.

[0052] (3) Preparation of the second precursor solution

[0053] 50g of the first MIL-101 crude product, 140g of chromium nitrate nonahydrate, and 74g of disodium terephthalate are weighed and mixed, 3.5L of pure water is added, and ultrasonic dispersion is performed for 100min to obtain the second precursor solution.

[0054] (4) Second spray drying

[0055] The second precursor solution is placed in a spray dryer, the feed rate of the spray dryer is set to 5mL / min, the flow rate is set to 75mL / min, and the inlet temperature is set to 160℃, and the second spray drying is performed, and the second MIL-101 crude product is collected through the collector of the spray dryer.

[0056] (5) Post-treatment

[0057] The second MIL-101 crude product is washed with hot pure water at 30℃ for 2h, centrifuged, dried, and ground to obtain the MIL-101 finished product.

[0058] Example 2

[0059] The synthesis method of the MIL-101 of the present application will be described in detail below through Examples 1-5:

[0060] (1) Preparation of the first precursor solution

[0061] Weigh 375.13g of aluminum nitrate nonahydrate and 210.9g of disodium terephthalate, add 5L of pure water, and disperse using ultrasound for 15min to obtain the first precursor solution.

[0062] (2) First spray drying

[0063] The first precursor solution was transferred into a spray dryer. The feed rate of the spray dryer was set to 6 mL / min, the flow rate to 80 mL / min, and the inlet temperature to 115℃. The first spray drying was carried out, and the first crude MIL-101 product was collected by the collector of the spray dryer.

[0064] (3) Prepare the second precursor solution

[0065] Weigh out 105g of the first MIL-101 crude product, 150g of aluminum nitrate nonahydrate, and 84g of disodium terephthalate, mix them, add 3.5L of pure water, and ultrasonically disperse for 30min to obtain the second precursor solution.

[0066] (4) Second spray drying

[0067] The second precursor solution was placed in a spray dryer, and the feed rate of the spray dryer was set to 4 mL / min, the flow rate to 100 mL / min, and the inlet temperature to 140 °C. A second spray drying was performed, and the second crude MIL-101 product was obtained by collecting it through the collector of the spray dryer.

[0068] (5) Post-processing

[0069] The second crude MIL-101 product was washed twice with hot pure water at 30°C for 2 hours, centrifuged, dried, and ground to obtain the finished MIL-101 product.

[0070] Example 3

[0071] The synthesis method of MIL101 in this embodiment is as follows:

[0072] (1) Preparation of the first precursor solution

[0073] Weigh 162g of ferric chloride nonahydrate and 210.9g of disodium terephthalate, add 5L of pure water, and disperse using ultrasound for 15min to obtain the first precursor solution.

[0074] (2) First spray drying

[0075] The first precursor solution was transferred into a spray dryer. The feed rate of the spray dryer was set to 5 mL / min, the flow rate to 90 mL / min, and the inlet temperature to 130℃. The first spray drying was carried out, and the first crude MIL-101 product was collected by the collector of the spray dryer.

[0076] (3) Prepare the second precursor solution

[0077] Weigh out 142g of the first MIL-101 crude product, 96g of ferric chloride nonahydrate, and 126g of disodium terephthalate, mix them, add 6L of pure water, and ultrasonically disperse for 30min to obtain the second precursor solution.

[0078] (4) Second spray drying

[0079] The second precursor solution was placed in a spray dryer, and the feed rate of the spray dryer was set to 4 mL / min, the flow rate to 80 mL / min, and the inlet temperature to 140 °C. A second spray drying was performed, and the second crude MIL-101 product was obtained by collecting it through the collector of the spray dryer.

[0080] (5) Post-processing

[0081] The second crude MIL-101 product was washed twice with hot pure water at 35°C for 2 hours, centrifuged, dried, and ground to obtain the finished MIL-101 product.

[0082] Example 4

[0083] The synthesis method of MIL101 in this embodiment is as follows:

[0084] (1) Preparation of the first precursor solution

[0085] Weigh 162g of ferric chloride nonahydrate and 168g of disodium terephthalate, add 5L of pure water, and disperse using ultrasound for 15min to obtain the first precursor solution.

[0086] (2) First spray drying

[0087] The first precursor solution was transferred into a spray dryer. The feed rate of the spray dryer was set to 3 mL / min, the flow rate to 50 mL / min, and the inlet temperature to 100℃. The first spray drying was carried out, and the first crude MIL-101 product was obtained by collecting it through the collector of the spray dryer.

[0088] (3) Prepare the second precursor solution

[0089] Weigh out 36.75g of the first MIL-101 crude product, 81g of ferric chloride nonahydrate, and 84g of disodium terephthalate, mix them, add 5L of pure water, and ultrasonically disperse for 10min to obtain the second precursor solution.

[0090] (4) Second spray drying

[0091] The second precursor solution was placed in a spray dryer, and the feed rate of the spray dryer was set to 3 mL / min, the flow rate to 50 mL / min, and the inlet temperature to 120 °C. A second spray drying was performed, and the second crude MIL-101 product was obtained by collecting it through the collector of the spray dryer.

[0092] (5) Post-processing

[0093] The second crude MIL-101 product was washed twice with hot pure water at 40°C for 1.5 hours, centrifuged, dried, and ground to obtain the finished MIL-101 product.

[0094] Example 5

[0095] The synthesis method of MIL101 in this embodiment is as follows:

[0096] (1) Preparation of the first precursor solution

[0097] Weigh 162g of ferric chloride nonahydrate and 252g of disodium terephthalate, add 5L of pure water, and disperse using ultrasound for 90min to obtain the first precursor solution.

[0098] (2) First spray drying

[0099] The first precursor solution was transferred into a spray dryer. The feed rate of the spray dryer was set to 20 mL / min, the flow rate to 200 mL / min, and the inlet temperature to 160℃. The first spray drying was carried out, and the first crude MIL-101 product was obtained by collecting it through the collector of the spray dryer.

[0100] (3) Prepare the second precursor solution

[0101] Weigh out 162g of the first MIL-101 crude product, 81g of ferric chloride nonahydrate, and 126g of disodium terephthalate, mix them, add 5L of pure water, and ultrasonically disperse for 120min to obtain the second precursor solution.

[0102] (4) Second spray drying

[0103] The second precursor solution was placed in a spray dryer, and the feed rate of the spray dryer was set to 20 mL / min, the flow rate to 200 mL / min, and the inlet temperature to 180 °C. A second spray drying was performed, and the second crude MIL-101 product was obtained by collecting it through the collector of the spray dryer.

[0104] (5) Post-processing

[0105] The second crude MIL-101 product was washed twice with hot pure water at 30°C for 3 hours, centrifuged, dried, and ground to obtain the finished MIL-101 product.

[0106] The MIL-101 products prepared in Examples 1, 2, and 3 were used as samples for performance testing as follows:

[0107] (1) Electron microscopy was performed on the finished MIL-101 products of Examples 1, 2, and 3 respectively, and the results are as follows: Figure 1 , Figure 2 and Figure 3 As shown. From Figures 1-3 As can be seen, the MIL-101 synthesized by chromium salt in Example 1 exhibits regular, complete, and uniformly sized octahedral crystals, with crystal sizes ranging from approximately 0.4 to 0.6 micrometers, consistent with the morphological characteristics of MIL-101(Cr). Furthermore, most crystal surfaces are smooth with sharp edges, demonstrating the high crystallinity of the MIL-101(Cr) synthesized by spray drying. However, we also observed small-particle impurities, which may be small-particle impurities synthesized during the secondary spray synthesis. Example 2 is MIL-101 synthesized by aluminum salt. Figure 2 Some of the small crystals appear octahedral, and the overall morphology resembles a "weathered rock block" formed by the accumulation of small crystals. The surface is not as smooth or has sharp edges as the chromium salt-synthesized MIL-101. Example 3 is an iron salt-synthesized MIL-101. Figure 3 As can be seen, the small particle impurities have been further increased, and it is now difficult to see clear octahedrons. The overall particle size distribution is only about 0.05-0.15 micrometers. Analysis of the electron microscopy images shows that Example 1 has the best synthesis results, while Example 3 has the worst results. This is consistent with the experience that MIL-101(Cr) is the easiest to synthesize and MIL-101(Fe) is the most difficult to synthesize.

[0108] (2) Nitrogen adsorption-desorption tests were performed on the MIL-101 products of Examples 1, 2, and 3, respectively. The results are as follows: Figure 4 As shown. Figure 4The nitrogen adsorption isotherms of Examples 1-3 are shown. Overall, in the low-pressure region of P / P0 = 0-0.3, the adsorption capacity of Examples 1-3 increases sharply, demonstrating the rich microporous characteristics of the synthesized materials of this invention. Among them, Example 1 has the highest adsorption capacity, Example 2 has the lowest, and Example 3 has a moderate adsorption capacity. Combined with the conclusions of scanning electron microscopy, the conclusions of Example 1 are consistent. Examples 2 and 3 show some differences, possibly related to the fact that the BET of MIL-101(Fe) is greater than that of MIL-101(Al). In summary, the synthesized examples possess rich microporous structures and all belong to type I adsorption isotherms, which are typical characteristics of MIL-101, proving that stable MIL-101 can be synthesized using the spray drying method.

[0109] (3) Water vapor cycle tests were conducted on the MIL-101 products of Examples 1, 2, and 3 respectively. The test equipment was a Bestech water vapor adsorption instrument. The adsorption test conditions were 60%RH and 25℃, with an adsorption time of 300 min. The desorption test conditions were 10%RH and 80℃, with a desorption time of 240 min. The number of cycles was 50. The water vapor cycle test results are shown in Table 1.

[0110]

[0111] Table 1

[0112] As can be seen from the data in Table 1, secondary spray drying synthesis can effectively improve the stability of the product. Taking Example 1 as an example, the performance of MIL-101 synthesized by primary spray drying decreased by 11.02% in the fiftieth adsorption test compared to the first adsorption test; while the performance of MIL-101 synthesized by secondary spray drying decreased by only 2.80%, thus proving that secondary spray drying can effectively improve the performance of MIL-101.

[0113] The foregoing description includes examples from this specification. Of course, for the purposes of describing this specification, it is impossible to describe every conceivable combination of components or methods; however, those skilled in the art will understand that many other combinations and arrangements are possible. Therefore, this specification is intended to cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, with regard to the use of the term "comprising" in the detailed description or claims, the term is intended to be inclusive in a manner similar to the term "including," as interpreted when "comprising" is used as a transitional word in the claims.

[0114] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A method for synthesizing MIL101, characterized in that, The method comprises the following steps: The metal salt and the disodium terephthalate are weighed and mixed, pure water is added, and ultrasonic dispersion is performed to obtain a first precursor solution; The first precursor solution is placed in a spray dryer, the inlet temperature of the spray dryer is set to 100-160 DEG C, and first spray drying is performed, and the first MIL-101 crude product is collected by a collector of the spray dryer; The first MIL-101 crude product, the metal salt and the disodium terephthalate are weighed and mixed, and pure water is added, and ultrasonic dispersion is performed to obtain a second precursor solution; The second precursor solution is placed in a spray dryer, the inlet temperature of the spray dryer is set to 120-180 DEG C, and second spray drying is performed, and the second MIL-101 crude product is collected by a collector of the spray dryer; The second MIL-101 crude product is washed, centrifuged, dried and ground to obtain the MIL-101 finished product.

2. The method of claim 1, wherein, The metal salt is selected from at least one of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, chromium nitrate nonahydrate and aluminum nitrate nonahydrate.

3. The method of claim 2, wherein, In the preparation of the first precursor solution, the molar ratio of the metal salt to the disodium terephthalate is 1:(0.8-1.2).

4. The method of claim 1, wherein, In the first spray drying, the feeding rate is set to 3-20 mL / min, and the flow rate is set to 50-200 mL / min.

5. The method of claim 4, wherein, In the first spray drying, the feeding rate is set to 10 mL / min, the flow rate is set to 150 mL / min, and the inlet temperature is set to 120 DEG C.

6. The method of claim 1, wherein, In the preparation of the second precursor solution, the molar ratio of the first MIL-101 crude product, the metal salt and the disodium terephthalate is (0.1-2):1:(0.8-1.2).

7. The method of claim 1, wherein, In the second spray drying, the feeding rate is set to 3-20 mL / min, and the flow rate is set to 50-200 mL / min.

8. The method of claim 7, wherein, In the second spray drying, the feeding rate is set to 5 mL / min, the flow rate is set to 75 mL / min, and the inlet temperature is set to 160 DEG C.

9. The method of claim 1, wherein, The washing is performed by using hot pure water at 30-40 DEG C for 1.5-3 h.

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