阅读说明：本技术 一种水酸竞争配位调控介孔UiO-66凝胶的制备方法和应用 (Preparation method and application of water-acid competitive coordination control mesoporous UiO-66 gel ) 是由 常刚刚 姚月 普春 张惠燕 黄崇鑫 于 2021-07-26 设计创作，主要内容包括：本发明公开了一种水酸竞争配位调控介孔UiO-66凝胶的制备方法和应用。其制备步骤为：1)将金属配体、有机配体、DMF、有机单羧酸和水均匀混合,进行溶剂热反应,反应结束后洗涤、纯化,得UiO-66材料；2)将UiO-66材料中加水后加热搅拌,然后加入琼脂糖继续搅拌,搅拌结束后自然冷却,然后真空冷冻干燥即得UiO-66凝胶。本发明通过改变原料中水/酸的比例以影响成核速度,进而调控凝胶的介孔尺寸,制备所得UiO-66凝胶具有介孔尺寸可调的分级结构和高的比表面积,有利于氮化物在孔道内的传输,对燃油中氮化物吸附容量较大,同时块状凝胶整体易于循环回收,再生性能良好。(The invention discloses a preparation method and application of a water-acid competitive coordination control mesoporous UiO-66 gel. The preparation method comprises the following steps: 1) uniformly mixing a metal ligand, an organic ligand, DMF (dimethyl formamide), organic monocarboxylic acid and water, carrying out solvothermal reaction, and washing and purifying after the reaction is finished to obtain a UiO-66 material; 2) adding water into the UiO-66 material, heating and stirring, then adding agarose, continuing stirring, naturally cooling after stirring, and then carrying out vacuum freeze drying to obtain the UiO-66 gel. According to the invention, the ratio of water to acid in the raw materials is changed to influence the nucleation speed, so that the mesoporous size of the gel is regulated, and the prepared UiO-66 gel has a hierarchical structure with adjustable mesoporous size and high specific surface area, is beneficial to the transmission of nitride in a pore channel, has large adsorption capacity on the nitride in fuel oil, and is easy to recycle and good in regeneration performance.)

1. A preparation method of a water-acid competitive coordination control mesoporous UiO-66 gel is characterized by comprising the following steps:

1) uniformly mixing a metal ligand, an organic ligand, DMF (dimethyl formamide), organic monocarboxylic acid and water, carrying out solvothermal reaction, and washing and purifying after the reaction is finished to obtain a UiO-66 material;

2) adding water into the UiO-66 material obtained in the step 1), heating and stirring, then adding agarose, continuing stirring, naturally cooling after stirring is finished, and then carrying out vacuum freeze drying to obtain the UiO-66 gel.

2. The method according to claim 1, wherein in the step 1), the metal ligand is zirconium chloride or hafnium chloride; the organic ligand is terephthalic acid, 2-amino terephthalic acid, 2, 5-dihydroxy terephthalic acid or 2-sulfonic acid monosodium terephthalate; the metal ligand and the organic ligand are mixed equimolar.

3. The method according to claim 1, wherein in the step 1), the organic monocarboxylic acid is formic acid, acetic acid, propionic acid, butyric acid or lauric acid.

4. The method according to claim 1, wherein in the step 1), the volume ratio of the organic monocarboxylic acid to the water is 1: 0-25.

5. The method according to claim 1, wherein in the step 1), the molar ratio of the metal ligand to the organic monocarboxylic acid is 1:4 to 10.

6. The preparation method according to claim 1, wherein in the step 1), the solvothermal reaction conditions are as follows: reacting for 12-24h at 60-180 ℃.

7. The preparation method according to claim 1, wherein in the step 2), the mass ratio of the UiO-66 material obtained in the step 1) to the agarose to the water is 1: 0.2-2: 50-100.

8. The method according to claim 1, wherein in the step 2), the heating temperature is 50 to 100 ℃ after the water is added; adding agarose and continuing stirring for 4-6 h; vacuum freeze drying for 12-48 hr.

9. Use of the UiO-66 gel prepared by the preparation method of any one of claims 1 to 8 in adsorption of nitrides in fuel oil.

10. Use according to claim 9, characterized in that the nitrides are pyridines, quinolines and derivatives thereof, indoles, carbazoles and derivatives thereof; the concentration of the nitride in the fuel oil is 10-3000 mg/L; the dosage of the UiO-66 gel in the fuel oil is 5-200 mg/ml.

Technical Field

The invention relates to the technical field of preparation and application of MOFs materials, in particular to a preparation method and application of a water-acid competitive coordination control mesoporous UiO-66 gel.

Background

With the development of social economy and scientific technology, automobiles are more and more popular, but the mass use of fuel oil also brings certain problems. In 2020, the consumption of gasoline and diesel oil in China is 1.4 hundred million tons and 2.2 hundred million tons respectively. The nitrides and sulfides in the fuel oil can generate a large amount of nitrogen oxides and sulfur oxides in the combustion process, thereby causing environmental problems and causing serious threats to human health. The nitrides in the fuel oil comprise basic nitrides (pyridine, quinoline, derivatives thereof and the like) and non-basic nitrides (indole, carbazole, derivatives thereof and the like). At present, hydrodenitrogenation is generally adopted, a hydrofining process is mature, the fuel yield is high, the product stability is good, but a large amount of hydrogen needs to be consumed, and the equipment investment and the operation cost are high. The nitride not only causes catalyst poisoning in the catalytic hydrogenation process, but also has strong inhibiting effect on hydrodesulfurization. Therefore, the development of a non-hydrogenation deep denitrification method with high selectivity is a difficult and urgent task.

The non-hydrogenation deep denitrification method mainly comprises acid refining, complexation, extraction, biological denitrification, oxidation, adsorption and the like. The adsorption denitrification is one of the most promising non-hydrogenation deep denitrification technologies at present, and has the advantages of mild operation conditions, low cost and wide applicability. The adsorption denitrification is to remove the nitride in the fuel oil under mild conditions through the interaction of the nitride and the surface of an adsorbent. High-efficiency porous adsorbent materials include carbon materials, pi-complex adsorbents, metal oxides, molecular sieves and the like, but the traditional materials have low adsorption capacity and are not beneficial to recovery.

Metal Organic Frameworks (MOFs) have attracted intense research interest in the last two decades as a relatively new class of porous crystalline materials. The diversity, customizability and high porosity of the structure thereof enable the MOFs to have great potential in multifunctional applicationsThe adsorbent has good development prospect. Porosity plays a key role in the structure and function of MOFs, and the pore size of currently reported MOFs is mainly the pore size, but the small pore size slows down diffusion rate and limits the transport of macromolecules, preventing their wide application. A hierarchical porous structure is constructed on an MOFs substrate with micropores as main parts, the micropores provide a high specific surface area, and the hierarchy (micropore/mesopore/macropore) constructed on the micropore substrate provides a required pore space for the transmission of macromolecules so as to realize rapid diffusion and improve the adsorption efficiency. Song et al reported that under mild reaction conditions, UiO-66 (with free-COOH) was directly synthesized in one step, and the obtained MOFs were used for adsorption removal of nitrogen-containing adsorbed denitrogenated compounds (indole (IND) adsorption and pyrrole) from model fuels, and this adsorbent has been widely used. Hou topic group reports porous two-dimensional metal organic framework (2D-MOF) nanosheets Zr-BTB-H4TBAPy and PCN-134-2D adsorbents, and the adsorbents have the advantages of large surface area, high water stability, capability of selectively adsorbing cationic dyes such as rhodamine B (RhB) and methylene blue (MLB) and the like, but the mesoporous size of pore channels of the adsorbents cannot be regulated and controlled. In addition, the MOFs has good development potential in the aspect of fuel oil denitrification, but most of MOFs adsorbents are in powder forms, are not beneficial to recycling after adsorption, and are difficult to meet the actual industrial requirements. Ahmed et al reported a UiO-66-NH with an amino group₂The adsorbents significantly removed indole and quinoline from model fuels based on hydrogen bonding, acid-base interactions, and cation-pi interactions. However, the powdered adsorbent is cumbersome to handle after adsorption and is not easily separated. Therefore, the development of the MOFs material which has large adsorption capacity on the nitride in the fuel oil and is easy to recover and recycle has important scientific significance and practical application value.

Disclosure of Invention

The invention aims to provide a preparation method of a water-acid competitive coordination control mesoporous UO-66 gel, the prepared UO-66 gel has adjustable mesoporous size, large adsorption capacity on nitride in fuel oil, easy recycling and stable circulation.

In order to solve the technical problems, the invention adopts the following technical scheme:

the preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

1) uniformly mixing a metal ligand, an organic ligand, DMF (dimethyl formamide), organic monocarboxylic acid and water, carrying out solvothermal reaction, and washing and purifying after the reaction is finished to obtain a UiO-66 material;

2) adding water into the UiO-66 material obtained in the step 1), heating and stirring, then adding agarose, continuing stirring, naturally cooling after stirring is finished, and then carrying out vacuum freeze drying to obtain the UiO-66 gel.

According to the scheme, in the step 1), the metal ligand is zirconium chloride or hafnium chloride; the organic ligand is terephthalic acid, 2-amino terephthalic acid, 2, 5-dihydroxy terephthalic acid or 2-sulfonic acid monosodium terephthalate.

According to the scheme, in the step 1), the metal ligand and the organic ligand are mixed in an equimolar mode.

According to the scheme, in the step 1), the organic monocarboxylic acid is formic acid, acetic acid, propionic acid, butyric acid or lauric acid.

According to the scheme, in the step 1), the volume ratio of the organic monocarboxylic acid to the water is 1: 0 to 25, preferably 1:1 to 10.

According to the scheme, in the step 1), the molar ratio of the metal ligand to the organic monocarboxylic acid is 1: 4-10.

According to the scheme, in the step 1), the solvothermal reaction conditions are as follows: reacting for 12-24h at 60-180 ℃.

According to the scheme, in the step 1), the washing and purifying process comprises the following steps: centrifugally washing with methanol and deionized water, and soaking and purifying with methanol for 48 h.

According to the scheme, in the step 2), the mass ratio of the UiO-66 material obtained in the step 1) to the agarose to the water is 1: 0.2-2: 50-100.

According to the scheme, in the step 2), the agarose is added and stirring is continued for 4-6 h.

According to the scheme, in the step 2), the heating temperature is 50-100 ℃ after water is added.

According to the scheme, in the step 2), vacuum freeze drying is carried out for 12-48 h.

Provides an application of the UiO-66 gel prepared by the preparation method in the aspect of adsorbing nitrides in fuel oil.

According to the scheme, the nitride is pyridine, quinoline and derivatives thereof, indole, carbazole and derivatives thereof.

According to the scheme, the concentration of the nitride in the fuel oil is 10-3000 mg/L.

According to the scheme, the dosage of the UiO-66 gel in the fuel oil is 5-200 mg/ml.

According to the scheme, the UiO-66 gel is placed in the fuel oil to oscillate at room temperature for a period of time to reach adsorption equilibrium.

The working mechanism of the invention is as follows:

on the one hand, water accelerates crystal nucleation through rapid hydrolysis of metal salts and dicarboxylic acid ligands; on the other hand, organic monocarboxylic acid terminal ligands coordinate to the metal atom to form soluble metal-carboxylate clusters, thereby slowing down the formation of MOF nucleation by bridging dicarboxylate ligands. The nucleation speed can be influenced by changing the ratio of water to acid, and the mesoporous size of the gel can be further regulated and controlled; and adding a proper amount of agarose to stabilize the gel for molding, wherein the molding of the gel is influenced by the amount of deionized water within a certain range. The prepared UiO-66 gel has large adsorption capacity on nitride in fuel oil, is easy to recycle and has stable circulation.

Compared with other fuel oil adsorption denitrification materials, the UiO-66 gel prepared by the invention has the following main advantages:

1. according to the invention, the ratio of water to acid in the raw materials is changed to influence the nucleation speed, so that the mesoporous size of the gel is regulated, and the prepared UiO-66 gel has a hierarchical structure with adjustable mesoporous size and high specific surface area, and is beneficial to the transmission of nitride in a pore channel and the acceleration of the adsorption rate.

2. The obtained UiO-66 gel has larger adsorption capacity to quinoline in fuel oil, which reaches 61.6mg/g and is higher than that of the traditional adsorption denitrification material.

3. The shape of the adsorbent is a gel block whole, the preparation process is simple, the conditions are mild, the adsorption is convenient for separation and recovery, and the industrial application requirements are met.

4. The chemical property is stable, the regeneration capacity is strong, and the adsorption capacity of the catalyst on quinoline is still 42.7mg/g after 5 times of circulation.

Drawings

FIG. 1 is an XRD pattern of UiO-66 gels prepared in examples 1-4.

FIG. 2 is an SEM image of a UiO-66 gel prepared in examples 1-4 and an optical image of a sample prepared in examples 2 and 4, wherein FIGS. a-d are sequential to examples 1-4.

FIG. 3 is the N of the UiO-66 gels prepared in examples 1-4₂Adsorption-desorption isotherms (upper panel) and pore size distribution curves (lower panel).

FIG. 4 is a graph of the adsorption kinetics of UiO-66 gel prepared in example 6 at 25 ℃ on quinoline.

FIG. 5 is a graph of the cycling performance of the UiO-66 gel prepared in example 6.

Detailed Description

The present invention will be further described with reference to the following examples and accompanying drawings, which are merely illustrative of preferred embodiments of the present invention and are not to be construed as limiting the invention.

Example 1

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

83mg of terephthalic acid, 117mg of zirconium chloride, 4.5ml of N-N dimethylformamide and 0.25ml of glacial acetic acid are added into a reaction kettle, and ultrasonic treatment is carried out at room temperature for 10min without adding deionized water. Putting the mixture into an oven, carrying out solvothermal reaction at 80 ℃ for 24h, and taking out the product. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48h with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 120mg of agarose when the temperature reaches 65 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in vacuum freeze-drying machine for 12h to obtain block UiO-66 gel. The volume of deionized water added was 0ml, and was designated UiO-66-0 gel. From the SEM image of FIG. 2, it can be seen that the morphology is regular octahedron, and the BET result indicates that the size of the prepared UiO-66-0 gel is mainly microporous, and the application of the gel to adsorption shows poor adsorption effect.

The application comprises the following steps: preparing 1000mg/L quinoline simulation oil by using n-octane as a solvent, taking 5ml of simulation oil, adding 50mg of UiO-66-0 gel as an adsorbent, oscillating at a constant temperature of 25 ℃ for a period of time to achieve adsorption equilibrium, and detecting by gas chromatography, wherein the residual concentration of quinoline is 869mg/L, the adsorption rate of quinoline is 13.1%, and the adsorption amount is 13.1 mg/g.

Example 2

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

83mg of terephthalic acid, 117mg of zirconium chloride, 4.5ml of N-N dimethylformamide, 0.25ml of glacial acetic acid and 0.5ml of deionized water were added to the reaction kettle, and sonication was carried out at room temperature for 10 min. Putting the mixture into an oven, carrying out solvothermal reaction at 130 ℃ for 24h, and taking out the product. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48h with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 50mg of agarose when the temperature reaches 80 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in vacuum freeze-drying machine for 12h to obtain block UiO-66 gel. The volume of deionized water added was 0.5ml, which was designated UiO-66-0.5 gel. The appearance of the gel is a hierarchical porous structure as seen from an SEM picture, and the BET result shows that the prepared UiO-66-0.5 gel has a mesoporous structure, the mesoporous size of the gel is 16.5nm, and the gel shows a good adsorption effect when being applied to adsorption.

The application comprises the following steps: preparing 1000mg/L quinoline simulation oil by using n-octane as a solvent, taking 5ml of simulation oil, adding 50mg of UiO-66-0.5 gel as an adsorbent, oscillating at a constant temperature of 25 ℃ for a period of time to achieve adsorption balance, and detecting by gas chromatography, wherein the residual concentration of quinoline is 577mg/L, the adsorption rate of quinoline is 42.3%, and the adsorption amount is 42.3 mg/g.

Example 3

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

83mg of terephthalic acid, 117mg of zirconium chloride, 4.5ml of N-N dimethylformamide, 0.25ml of glacial acetic acid and 1ml of deionized water are added into the reaction kettle, and ultrasonic treatment is carried out at room temperature for 10 min. Putting the mixture into an oven, carrying out solvothermal reaction at 100 ℃ for 12h, and taking out the product. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48h with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 180mg of agarose when the temperature reaches 70 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in a vacuum freeze-drying machine for 12h to obtain UiO-66 gel. The volume of deionized water added was 1ml and was reported as UiO-66-1 gel. The appearance of the gel is a hierarchical porous structure as seen from an SEM image, and the BET result shows that the prepared UiO-66-1 gel has a mesoporous structure, the mesoporous size of the gel is 10.6nm, and the gel shows a good adsorption effect when applied to adsorption.

The application comprises the following steps: preparing 1000mg/L quinoline simulation oil by using n-octane as a solvent, taking 5ml of simulation oil, adding 50mg of UiO-66-1 gel as an adsorbent, oscillating at a constant temperature of 25 ℃ for a period of time to reach adsorption equilibrium, and detecting by gas chromatography, wherein the residual concentration of quinoline is 672mg/L, the adsorption rate of quinoline is 32.8%, and the adsorption amount is 32.8 mg/g.

Example 4

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

83mg of terephthalic acid, 160mg of hafnium chloride, 4.5ml of N-N dimethylformamide, 0.25ml of glacial acetic acid and 6ml of deionized water were added to the reaction kettle, and sonication was carried out at room temperature for 10 min. Putting into an oven, carrying out solvothermal reaction at 100 ℃, and taking out after 12 h. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48h with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 100mg of agarose when the temperature reaches 70 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in vacuum freeze-drying machine for 12h to obtain block UiO-66-NH₂And (4) gelling. The volume of deionized water added was 6ml, and was designated UiO-66-6 gel. The appearance of the gel is a hierarchical porous structure as seen from an SEM picture, and a BET result shows that the prepared UiO-66-0.5 gel has a mesoporous structure, the mesoporous size of the gel is 4.0nm, and the gel shows a good adsorption effect when being applied to adsorption.

The application comprises the following steps: preparing 1000mg/L quinoline simulation oil by using n-octane as a solvent, taking 5ml of simulation oil, adding 50mg of UiO-66-6 gel as an adsorbent, oscillating at a constant temperature of 25 ℃ for a period of time to achieve adsorption equilibrium, and detecting by gas chromatography, wherein the residual concentration of quinoline is 773mg/L, the adsorption rate of quinoline is 22.7%, and the adsorption amount is 22.7 mg/g.

Example 5

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

99mg of 2, 5-dihydroxyterephthalic acid, 117mg of zirconium chloride, 4.5ml of N-dimethylformamide, 0.25ml of propionic acid and 0.5ml of deionized water were added to the reaction vessel, and sonication was carried out at room temperature for 10 min. Putting the mixture into an oven, carrying out solvothermal reaction at 150 ℃ for 24h, and taking out the product. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48 hours with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 130mg of agarose when the temperature reaches 70 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in vacuum freeze-drying machine for 12h to obtain UiO-66-OH₂And (4) gelling. The volume of deionized water added was 0.5ml, which was designated UiO-66-OH₂-0.5 gel.

The application comprises the following steps: preparing 1000mg/L indole simulation oil with n-octane as solvent, collecting 5ml simulation oil, and adding 50mg of the above UiO-66-OH₂-0.5 gel as adsorbent, oscillating at constant temperature of 25 ℃ for a period of time to reach adsorption equilibrium, and detecting by gas chromatography, wherein the residual concentration of indole is 556mg/L, the adsorption rate of indole is 44.4%, and the adsorption amount is 44.4 mg/g.

Example 6

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

90.5mg of 2-aminoterephthalic acid, 117mg of zirconium chloride, 4.5ml of N-N dimethylformamide, 0.25ml of glacial acetic acid and 0.5ml of deionized water were added to the reaction kettle and subjected to ultrasonic treatment at room temperature for 10 min. Putting the mixture into an oven, carrying out solvothermal reaction at 150 ℃ for 24h, and taking out the product. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48 hours with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 130mg of agarose when the temperature reaches 70 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in a vacuum freeze-drying machine for 12h to obtain UiO-66-NH₂And (4) gelling. The volume of deionized water added was 0.5ml, which was designated UiO-66-NH₂-0.5 gel.

The application comprises the following steps: preparing 1000mg/L quinoline simulation oil by using n-octane as a solvent, taking 200ml of simulation oil and adding 2.0g of the UiO-66-NH₂-0.5 gel as adsorbent, sampling at constant temperature of 25 ℃ with shaking at intervals, and performing gas chromatography detection, wherein the adsorption equilibrium is reached within 2h, the equilibrium residual concentration of quinoline is 384mg/L, the adsorption rate is 61.6%, and the adsorption amount is 61.6 mg/g. Mixing UiO-66-NH₂After the gel is washed and desorbed by the absolute ethyl alcohol, the gel continues to adsorb 1000mg/L of quinoline simulation oil, and after 5 times of circulation, the adsorption amount of quinoline still remains 42.7 mg/g.

Example 7

The preparation method of the water-acid competitive coordination control mesoporous UiO-66 gel comprises the following steps:

134mg of 2-sulfonic acid monosodium terephthalate, 117mg of zirconium tetrachloride, 4.5ml of N-N dimethylformamide, 0.25ml of lauric acid and 0.5ml of deionized water were added to the reaction kettle, and sonication was performed at room temperature for 10 min. Putting the mixture into an oven, carrying out solvothermal reaction at 100 ℃ for 24h, and taking out the product. And (3) centrifugally washing with methanol and deionized water, soaking and purifying for 48h with methanol, adding 10ml of deionized water into the centrifuged product, heating and stirring in an oil bath, and adding 150mg of agarose when the temperature reaches 70 ℃. Stirring for 4h, standing for natural cooling, and freeze-drying in vacuum freeze-drying machine for 12h to obtain UiO-66-SO₃-0.5 gel. The volume of deionized water added was 0.5ml, which was designated UiO-66-SO₃-0.5 gel.

The application comprises the following steps: preparing 1000mg/L indole simulation oil with n-octane as solvent, collecting 5ml simulation oil, and adding 50mg of the above UiO-66-SO₃-0.5 gel as adsorbent, oscillating at constant temperature of 25 ℃ for a period of time to reach adsorption equilibrium, and detecting by gas chromatography, wherein the residual concentration of indole is 520mg/L, the adsorption rate of indole is 48.0%, and the adsorption amount is 48.0 mg/g.

It should be emphasized that the above-described examples are merely illustrative and not restrictive of the embodiments, and that those skilled in the art, on the basis of the preceding description, may make modifications in other forms, which do not necessarily require all embodiments to be given, but which, as such, are obvious variations and modifications thereto, all falling within the scope of the invention.