Device and method for steam-assisted continuous green preparation of MOF (Metal Organic Framework)

Abstract

The invention relates to the field of adsorption materials, in particular to a device and a method for steam-assisted continuous green preparation of MOF (Metal Organic Frame.The method comprises the following steps: grinding reactants, carrying out ammonia-assisted treatment, and carrying out steam-phase reaction by taking water as a solvent to prepare UTSA-280. According to the continuous production, the advantage of high solid-phase reaction speed of a steam phase is fully utilized, the time is saved, the problem that the structure and the performance of each batch of products are possibly fluctuated due to re-feeding each time during intermittent production is solved, the products continuously produced by the steam phase are more uniform, have the same structure and good performance and are high in single-time yield, the yield can reach 91%, and the production cost is reduced. And the kilogram-level UTSA-280 material can be rapidly prepared. Meanwhile, the reaction raw materials are treated in an auxiliary manner through ammonia, so that the reaction yield can be increased, the reaction can be accelerated, the formation of a coordination structure of the MOF is facilitated, and the performance of the MOF is further improved. Ammonia auxiliary treatment is carried out in the vapor phase reaction, the reaction can be accelerated, the reaction is more sufficient and thorough, and then higher yield and shorter reaction time are obtained.

Description

Technical Field

[0001] The present invention relates to the field of adsorption materials, and in particular to a device and method for steam-assisted continuous green preparation of MOF. Background Art

[0002] Metal-organic framework (MOF) materials are a new type of porous crystalline materials. They have attracted widespread attention due to their advantages such as high porosity, large specific surface area, and adjustable pore size. In view of the structural diversity and designability of this type of material, it shows good application potential in the fields of adsorption separation, sensing, catalysis, etc. Although MOF materials have shown unparalleled performance advantages in many application fields, the large-scale industrial application of this type of material is still slow. The primary obstacle is the high cost of MOF preparation and the lack of large-scale continuous preparation methods. Many MOF synthesis methods reported so far have disadvantages such as long reaction time, low yield, and high solvent consumption. In particular, the use of organic polluting solvents such as N,N-dimethylformamide, acetonitrile, etc., these toxic solvents cause serious damage to the environment and increase the cost of MOF preparation.

[0003] Among the green preparation methods of MOF materials, the vapor phase method is a very distinctive MOF preparation method. This method has the characteristics of fast solid-phase reaction nucleation, short time consumption, and small amount of solvent used. It can even use only water as solvent for the reaction, greatly reducing the amount of solvent used and thus reducing costs, while maintaining a high yield, and is expected to achieve efficient and green continuous production of MOF materials.

[0004] The ultra-microporous structure of the rigid one-dimensional channel of UTSA-280 material can play a role in molecular sieving, allowing C 2 H 4 Completely block C 2 H 6 , achieving very good C 2 H 4 / C 2 H 6 Separation effect, while the size of MOF is larger than CO 2 The dynamic diameter Less than N 2 The dynamic diameter CO 2 / N 2 There is also a size screening effect in the separation. UTSA-280 can maintain the stability of its structure and adsorption performance in a wide pH range (pH = 1-12), and can also be processed into particles or powders of different sizes and shapes through different methods to adapt to different application scenarios and needs.

[0005] The traditional method for synthesizing UTSA-280 is to use Ca(NO 3 )2 As a metal source, it will cause the enrichment of nitrate ions in the continuous reaction, affecting the separation performance of the synthesized UTSA-280. In addition, nitrates are explosive chemicals, which are difficult to purchase, expensive, and have great harm to the environment, which is not conducive to actual production applications. In the prior art, US20210284661A discloses the mechanochemical synthesis of metal-organic frameworks for molecular sieving, their compositions, and their use methods. UTSA-280 can be prepared from calcium oxide (CaO) or calcium hydroxide (Ca(OH) 2 ) and squaric acid (SA) are synthesized by mechanochemical synthesis, and UTSA-280 is prepared by adding water. This method has the problems of unstable MOF structure, long reaction time and need for further activation in large-scale preparation. However, this method has the problems of decreased yield and unstable product structure in continuous production.

[0006] Based on this, it is necessary to seek a continuous and green method for preparing MOF and safely and greenly prepare UTSA-280 materials. Summary of the invention

[0007] The present invention overcomes the shortcomings of the prior art and provides a device and method for the green preparation of MOF by steam-assisted continuous processing. UTSA-280 is prepared by using low-cost metal sources Ca(OH) or CaO and green solvent water. With the assistance of ammonia, the reaction time is shortened and the crystallinity is improved, thereby realizing the continuous production of kilogram-level MOF on a laboratory scale. The method is also extended to the synthesis of materials such as MOF-303 and MIL-53(Al).

[0008] The technical solution adopted by the present invention is:

[0009] A steam-assisted continuous green preparation device for MOF comprises a steam generator and a conveyor. A feeder and a receiver are respectively arranged at both ends of the conveyor. A MOF placer is arranged above the conveyor and a heating platform is arranged below the conveyor. The ligand of the MOF is acidic.

[0010] A method for preparing MOF in a continuous and green manner by steam-assisted reaction is carried out using the above-mentioned device, and comprises the following steps:

[0011] A. Mix and grind the reaction raw materials (metal and ligand molar ratio 1:1);

[0012] B. subjecting the mixture of step A to ammonia-assisted treatment;

[0013] C. Add the mixture of step B into the feeder, turn on the conveyor, convey the MOF to the steam generator, and turn on the heating table to react. After the reaction is completed, turn on the conveyor again, convey the tail end of the MOF, and collect it with a receiver.

[0014] Furthermore, the ligand of the MOF is acidic, the reaction raw materials are MOF metal raw materials and ligands corresponding to MOF, and the MOF metal raw materials are metal salts, metal oxides or metal hydroxides corresponding to the MOF.

[0015] Furthermore, the MOF material is one of UTSA-280, MOF-303, and MIL-53 (Al).

[0016] Furthermore, when the prepared MOF material is UTSA-280, the molar ratio of the raw materials in step A is 1:1.

[0017] Furthermore, when the prepared MOF material is UTSA-280, the volume fraction of ammonia water used in the ammonia-assisted treatment in step B is 10%.

[0018] Further, when the prepared MOF material is UTSA-280, the temperature of the heating stage in step C is 120°C.

[0019] Furthermore, when the prepared MOF material is UTSA-280, the solvent in the steam generator in step C is water.

[0020] Technical Effects

[0021] The present invention adopts a vapor phase method to rapidly synthesize UTSA-280, which has a short reaction time, low cost, convenient preparation method, simple operation, and is conducive to industrial production. This is because continuous production fully utilizes the advantage of fast vapor phase solid phase reaction speed. Feeding, reaction, and discharging are a relatively short process. Continuous production takes a short time and has a higher output than intermittent production in the same time. In addition, the pre-treated materials are continuously added, which saves time and solves the problem that each batch of product structure and performance may fluctuate due to re-feeding in intermittent production. The products produced continuously in the vapor phase are more uniform, have the same structure, and maintain good performance.

[0022] The present application also uses ammonia to assist in the treatment of the reaction raw materials, which can not only improve the reaction yield, but also speed up the reaction, which is conducive to the formation of the coordination structure of MOF, thereby improving the performance of MOF. This is because the reaction raw materials of the present application are pre-mixed with acidic ligands and metal salts or metal oxides, and the raw materials are treated with ammonia to assist in the treatment. On the one hand, the acidic ligands are quickly dissolved in a low humidity environment, and on the other hand, ammonia water will ionize hydroxides, which can achieve the deprotonation of the ligands and accelerate the coordination of the metal salts or metal oxides with the ligands. UTSA-280, MOF-303, and MIL-53(Al) can all be prepared using this method. This is because the ligands of UTSA-280, MOF-303, and MIL-53(Al) are squaric acid, pyrazole-3,5-dicarboxylic acid, and terephthalic acid, respectively. These three ligands are acidic. Especially in the synthesis of UTSA-280, the acid dissolves slowly, so the reaction rate is slow. The vapor phase reaction puts the reactants in a slightly moist environment during the entire reaction process. Ammonia-assisted treatment can speed up the reaction and make the reaction more complete and thorough, thereby obtaining a higher yield and a shorter reaction time. The UTSA-280 obtained has a very good reaction rate for CO 2 The adsorption capacity is also higher.

[0023] The method of the present invention achieves an optimal performance and meets the requirements of industrial application by controlling the ammonia-assisted synthesis. The synthesis of UTSA-280 by steam phase is simple to operate, short reaction time, high single yield, up to about 150g, and the yield can reach 91%. By using the equipment for continuous production, 1 kg of UTSA-280 material can be prepared in 7 hours. At 298K, CO 2 The adsorption capacity can reach 56cm3 / g, and the adsorption performance is stable, which is conducive to promoting the large-scale production of MOF materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the device for the steam-assisted continuous green preparation of MOF materials of the present invention;

[0025] Steam generator (1), conveyor (2), heating table (3), feeder (4), receiver (5), MOF placer (6);

[0026] Figure 2 This is the XRD diagram of the raw material of UTSA-280 material prepared by steam-assisted continuous green method and after grinding in the embodiment of the present invention;

[0027] Figure 3 XRD diagram of the UTSA-280 material synthesized by ammonia-assisted steam-assisted continuous green preparation and pure water vapor-assisted UTSA-280 material in the embodiment of the present invention;

[0028] Figure 4 This is the XRD diagram of the ammonia-assisted steam-assisted continuous green preparation of MOF-303 material in an embodiment of the present invention;

[0029] Figure 5 The CO of the UTSA-280 material synthesized by ammonia-assisted steam-assisted continuous green preparation of UTSA-280 material and pure water steam in the embodiment of the present invention is 2 Adsorption isotherm (298K);

[0030] Figure 6 N is the steam-assisted continuous green preparation of MOF-303 material in the embodiment of the present invention. 2 Adsorption isotherm (77K);

[0031] Figure 7 This is a water absorption curve (298K) of the steam-assisted continuous green preparation of MOF-303 material in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments.

[0033] like Figure 1 As shown, a steam-assisted continuous green preparation device for MOF comprises a steam generator (1), a conveying device (2), a feeder (4) and a receiver (5) are respectively provided at both ends of the conveying device (2), and a MOF placement device (6) is provided above the conveying device (2), and a heating platform (3) is provided below.

[0034] The method for preparing UTSA-280 in a continuous green manner using steam as an aid is described in the embodiment, and comprises the following steps:

[0035] A. Add calcium hydroxide and squaric acid into a mortar and grind them together in a molar ratio of 1:1;

[0036] B. subjecting the mixture of step A to ammonia-assisted treatment;

[0037] C. Add the mixture of step B into the feeder, turn on the conveyor, convey the MOF to the steam generator, and turn on the heating table to heat to 120°C for reaction. After the reaction is completed, turn on the conveyor again, convey the tail end of the MOF, and collect it with a receiver.

[0038] Example 1

[0039] Ca(OH) 2Mix 1 mol of each with 1:1 molar ratio of square acid and add them into a mortar, grind manually for 5 minutes, spray 5 mL of ammonia solution (10% volume fraction) on the ground reactant, then load the reactant into the feeder, turn on the heating table, heat the water to 100°C and boil, start the conveyor, and convey the reactant to the steam generator for steam phase reaction for 1 hour. After the reaction is completed, turn on the conveyor again, convey the tail end of MOF, and collect it with a receiver. The synthesized sample is recorded as sample C, and the yield of the product is 91%.

[0040] Example 2

[0041] AlCl 3 6H 2 O and 3,5-pyrazole dicarboxylic acid were mixed in a molar ratio of 1:1, 1 mol each, added to a mortar, and ground manually for 5 minutes. The ground reactants were sprayed with 5 mL of ammonia solution (10% volume fraction), and then the reactants were loaded into the feeder, the heating table was turned on, the water was heated to 100°C for boiling, the conveyor was started, and the reactants were conveyed to the steam generator for steam phase reaction for 8 hours. After the reaction was completed, the conveyor was turned on again, the MOF was conveyed to the tail end, and collected with a receiver. The synthesized sample was recorded as sample D, and the yield of the product was 91%.

[0042] Comparative Example 1

[0043] Ca(OH) 2 The mixture was mixed with 1 mol of squaric acid in a molar ratio of 1:1 and added into a mortar, and ground manually for 5 min. The obtained sample was recorded as sample A.

[0044] Comparative Example 2

[0045] Ca(OH) 2 Mix 1 mol of each with 1:1 molar ratio of square acid and add them into the mortar, grind manually for 5 minutes, load the ground reactant into the feeder, turn on the heating table, heat the water to 100℃ and boil, start the conveyor, convey the reactant to the steam generator for steam phase reaction for 1 hour, after the reaction is completed, turn on the conveyor again, convey the tail end of MOF, and collect it with a receiver. The synthesized sample is recorded as sample B, and the yield of the product is 62%.

[0046] Performance test example

[0047] 1. The crystal structures of the samples prepared in Comparative Examples 1 and 2 and the samples prepared in Implementation Examples 1 and 2 of the present invention were characterized by using a Bruker D8Advance X-ray diffractometer.

[0048] 2. Adoption The TriStar II Plus fully automatic surface area and porosity analyzer was used to analyze the CO of the samples prepared in Examples 1 to 2 of the present invention. 2 The adsorption capacity and specific surface area were measured.

[0049] 3. The water adsorption of the sample prepared in Example 2 of the present invention was measured using the BELSORP-MAXⅡ physical vapor adsorption instrument produced by Bayer, Germany.

[0050] Results Analysis

[0051] like Figure 2-3 As shown in the figure, the starting materials did not generate UTSA-280 material after grinding. Sample A did not react, indicating that it was impossible to generate UTSA-280 without the ammonia treatment process. Combined with the situation of samples B and C, it can be shown that Example 1 can obtain UTSA-280 material with higher crystallinity under the ammonia-assisted vapor phase. Figure 4 The spectrum of sample D shown is consistent with that of MOF-303, indicating that Example 2 successfully prepared MOF-303, and verifying that the present device can successfully prepare UTSA-280 and MOF-303 materials.

[0052] like Figure 5 As shown, CO of sample B and sample C 2 Adsorption isotherm, CO of sample B synthesized in pure water system at 298K 2 The adsorption capacity is only 44.2cm 3 / g, CO of sample C synthesized with the aid of ammonia 2 The adsorption capacity can reach 55.8cm 3 / g, which shows that under ammonia-assisted treatment, the reaction can be accelerated and the MOF structure can be effectively improved to obtain products with strong adsorption capacity.

[0053] like Figure 6-7 As shown, N of sample D 2 Adsorption isotherm (77K), the specific surface area of ​​the sample is 914m 2 / g, the water absorption capacity of MOF-303 synthesized in the steam phase is 0.36gg at 298K and 30%RH. -1 .

[0054] Table 1 Performance results of samples B to D

[0055]

[0056] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A steam-assisted continuous green preparation device for MOF, characterized in that: The invention comprises a steam generator and a conveying device. A feeder and a receiver are respectively arranged at two ends of the conveying device. A MOF placer is arranged above the conveying device, and a heating platform is arranged below the conveying device.

2. A method for steam-assisted continuous green preparation of MOF, the method adopts the steam-assisted continuous green preparation of MOF device as claimed in claim 1 for preparation, characterized in that: The method comprises the following steps: A. Mixing and grinding the reaction raw materials; B. subjecting the ground MOF to ammonia-assisted treatment; C. Add the mixture of step B into the feeder, turn on the conveyor, convey the MOF to the steam generator, and turn on the heating stage to react. After the reaction is completed, turn on the conveyor again, convey the tail end of the MOF, and collect it with a receiver; The ligand of the MOF is acidic, the reaction raw materials are MOF metal raw materials and ligands corresponding to MOF, and the MOF metal raw materials are metal salts, metal oxides or metal hydroxides corresponding to the MOF.

3. A method for preparing MOF in a continuous and green manner by steam-assisted method as claimed in claim 2, characterized in that: The MOF is UTSA-280, MOF-303, MIL-53 (Al) and the like.

4. A method for preparing MOF in a continuous and green manner by steam-assisted method as claimed in claim 2, characterized in that: When the MOF material in step A is UTSA-280, the molar ratio of the raw materials is 1:

1.

5. A method for preparing MOF in a continuous and green manner by steam-assisted method as claimed in claim 2, characterized in that: The volume fraction of ammonia water used in the ammonia-assisted treatment in step B is 10%.

6. A method for preparing MOF in a continuous and green manner by steam-assisted method as claimed in claim 2, characterized in that: The temperature of the heating stage in step C is 120°C.

7. A method for preparing MOF in a continuous and green manner by steam-assisted method as claimed in claim 2, characterized in that: The solvent in the steam generator in step C is water.

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