Imidazole boron framework material as well as preparation method and application thereof

Abstract

The invention discloses an imidazole boron framework material as well as a preparation method and application thereof, and belongs to the technical field of nano porous materials. The imidazole boron framework material provided by the invention is obtained by coordinating and assembling metal zinc ions and a tri-imidazole boron hydride, and free anions of the imidazole boron framework material are Cl <-> or OH <->; the preparation method comprises the following steps: dissolving zinc chloride or zinc hydroxide, a triimidazole hydroboron compound, 2-imidazolidinone and trimesic acid in a solvent, reacting at 70-90 DEG C to obtain a solid product, and then performing vacuum activation on the solid product to obtain the compound. The imidazole boron framework material provided by the invention has a relatively high adsorption capacity ratio to acetylene and carbon dioxide, shows relatively high adsorption selectivity, is easily available in synthesis raw materials, simple in preparation process and relatively low in cost, and has a good application prospect in the field of separation of acetylene and carbon dioxide mixed gas.

Description

Technical Field

[0001] The invention relates to the technical field of nanoporous materials, and in particular to an imidazole boron skeleton material and a preparation method and application thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Acetylene is a very important industrial gas that can be used as fuel and is widely used in the production of chemicals such as vinyl chloride, acrylic acid, and 1,4-butynediol. The main source of acetylene is the petroleum distillation and cracking process, which inevitably produces carbon dioxide impurities, resulting in a decrease in the purity of acetylene, which is not conducive to subsequent use. Therefore, how to efficiently remove carbon dioxide and obtain high-purity acetylene is of great significance. The molecules of acetylene and carbon dioxide are both linear in shape, with molecular sizes of and They have the same kinetic diameter The boiling points of acetylene and carbon dioxide are similar (189.3K and 194.7K, respectively), so separation is difficult. Traditional separation methods such as solvent extraction and cryogenic distillation are costly and energy-intensive.

[0004] Metal-Organic Frameworks (MOFs) are an emerging porous material, an inorganic-organic hybrid porous solid material, which uses organic ligands as bridges to self-assemble inorganic metal ions / clusters into periodic structures through coordination bonds. Metal-organic frameworks have attracted widespread attention in the fields of gas storage and separation due to their large specific surface area and porosity, as well as abundant active sites.

[0005] Zeolite-like MOFs with zeolite topology have become a hot topic in the field of chemistry and materials due to their periodic network structure, adjustable pore size and customizable microenvironment. Boron imidazolate framework (BIFs) is a zeolite-like metal organic framework that connects ultralight elements (such as Li and B) through BN covalent bonds. Boron, as a lighter element, can effectively reduce the density of the BIF framework and is considered to be a promising material in the field of gas storage and separation. There are reports on the use of boron imidazolate frameworks in gas separation in the prior art, but they are mostly used for the separation of carbon dioxide from gases such as methane, ethane, and ethylene, while there are few reports on boron imidazolate framework materials with high acetylene / carbon dioxide selectivity. Summary of the invention

[0006] In view of this, the present invention provides an imidazole boron framework material and a preparation method and application thereof. The imidazole boron framework material provided by the present invention can effectively separate carbon dioxide and acetylene mixed gas, is energy-saving and efficient, and the preparation method is simple and low-cost.

[0007] In a first aspect, the present invention provides an imidazole boron framework material, which is obtained by coordination and assembly of metal zinc ions and triimidazole boron hydride compounds, wherein the free anion of the imidazole boron framework material is Cl - or OH - .

[0008] Preferably, the triimidazole borohydride compound is obtained by reacting potassium borocyanide and 2-methylimidazole.

[0009] In a second aspect, the present invention provides a method for preparing the above-mentioned imidazole boron framework material, comprising the following steps:

[0010] Dissolve zinc chloride or zinc hydroxide, triimidazole borohydride compound, 2-imidazolidinone and trimesic acid in a solvent, react at 70-90° C. to obtain a solid product, and then activate the solid product in vacuum to obtain the product.

[0011] Preferably, the molar ratio of the zinc chloride or zinc hydroxide, the triimidazole borohydride compound, 2-imidazolidinone and trimesic acid is 1:(0.3-0.6):(10-15):(0.3-0.6).

[0012] Preferably, the usage ratio of the triimidazole borohydride compound to the solvent is (0.5-0.7) g: (30-70) mL.

[0013] Preferably, the solvent is selected from a mixed solvent of N,N-dimethylformamide, 3-aminopropanol and ethanol, and the volume ratio of N,N-dimethylformamide, 3-aminopropanol and ethanol is (1-3):(1-3):(1-3).

[0014] Preferably, in the step of obtaining a solid product by reacting at 70 to 90° C., the reaction time is 20 to 80 hours.

[0015] Preferably, after the reaction is completed, the method further comprises the steps of washing and drying the reaction product to obtain a solid product.

[0016] Preferably, in the vacuum activation step, the vacuum degree is 10 -7 mbar or less, the temperature is 120-170℃, and the time is 5-15h.

[0017] Preferably, the preparation method of the triimidazole borohydride compound is: potassium borocyanide and 2-methylimidazole are mixed, and a melting reaction is carried out at 200-230° C. to obtain the triimidazole borohydride compound.

[0018] Furthermore, the molar ratio of potassium borocyanide to 2-methylimidazole is 1:(3-3.5); and the reaction time of potassium borohydride and 2-methylimidazole is 3-8 hours.

[0019] In a third aspect, the present invention provides the use of the imidazole boron framework material or the imidazole boron framework material prepared by the above preparation method in the separation of acetylene and carbon dioxide mixed gas.

[0020] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0021] The imidazole boron skeleton material provided by the present invention has a higher adsorption ratio for acetylene and carbon dioxide and exhibits higher adsorption selectivity. Moreover, the synthetic raw materials are easily available, the preparation process is simple, and the cost is low. Therefore, the imidazole boron skeleton material has good application prospects in the field of separation of acetylene and carbon dioxide mixed gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation of the present invention. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is BIF-24 (Cl of Example 1 of the present invention - ) and BIF-24 (OH - ), wherein a, Example 1; b, Example 2;

[0024] Figure 2 It is BIF-24 (Cl of Example 1 of the present invention - ) and BIF-24 (OH - ), wherein a, Example 1; b, Example 2;

[0025] Figure 3 It is BIF-24 (Cl of Example 1 of the present invention - ) Single component adsorption curves of acetylene (a) and carbon dioxide (b) at different temperatures;

[0026] Figure 4 It is BIF-24 (OH) of Example 2 of the present invention. - ) Single component adsorption curves of acetylene (a) and carbon dioxide (b) at different temperatures;

[0027] Figure 5 The imidazole boron framework material BIF-24 (Cl- (a) The imidazole boron framework material BIF-24 (OH - ) (b) and BIF-24 (NO3 of Comparative Example 1 - (c) acetylene / carbon dioxide selectivity diagram calculated by ideal adsorption solution theory at different temperatures;

[0028] Figure 6 The imidazole boron framework material BIF-24 (Cl - (a) The imidazole boron framework material BIF-24 (OH - (b) Gas adsorption ratio of acetylene to carbon dioxide;

[0029] Figure 7 The imidazole boron framework material BIF-24 (Cl - ) (a) and the imidazole boron framework material BIF-24 (OH - )(b) Two-component acetylene / carbon dioxide breakthrough diagram. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] The present invention provides an imidazole boron framework material, which is obtained by coordination and assembly of metal zinc ions and triimidazole boron hydride compounds, wherein the free anion of the imidazole boron framework material is Cl - or OH - .

[0032] The imidazole boron skeleton material provided by the present invention has a ctn type topological structure and is based on Cl - or OH - As free anions, free anions will affect the morphology of imidazole boron framework materials. - When it is a free anion, the imidazole boron skeleton material mostly presents a rhombic dodecahedron structure; when it is OH - When it is a free anion, the imidazole boron framework material mostly presents a spherical structure. Both have good separation performance for the mixed gas of carbon dioxide and acetylene, and the selectivity of acetylene / carbon dioxide is above 3.9.

[0033] In the present invention, the triimidazole borohydride compound is obtained by reacting potassium borocyanide and 2-methylimidazole, and the organic ligand of the triimidazole borohydride compound obtained by the reaction of the two is KHB(mim)3.

[0034] The present invention also provides a method for preparing the imidazole boron framework material, comprising the following steps:

[0035] Dissolve zinc chloride or zinc hydroxide, triimidazole borohydride compound, 2-imidazolidinone and trimesic acid in a solvent, react at 70-90° C. to obtain a solid product, and then activate the solid product in vacuum to obtain the product.

[0036] In the above reaction process of the present invention, the imidazole boron framework material is synthesized by the solvent thermal reaction of the self-assembly of zinc chloride or zinc hydroxide and triimidazole boron hydride compound. 2-Imidazolidinone and trimesic acid do not participate in the construction of the imidazole boron framework material, but they play the role of environmental factors in the synthesis of the imidazole boron framework material. If 2-imidazolidinone and trimesic acid are lacking, the imidazole boron framework material of the present invention cannot be obtained.

[0037] In the present invention, the molar ratio of the zinc chloride or zinc hydroxide, the triimidazole borohydride compound, 2-imidazolidinone and trimesic acid is 1:(0.3-0.6):(10-15):(0.3-0.6).

[0038] In the present invention, the ratio of the triimidazole borohydride compound to the solvent is (0.5-0.7) g: (30-70) mL. A suitable amount of solvent is conducive to the smooth progress of the reaction.

[0039] In the present invention, the solvent is selected from a mixed solvent of N,N-dimethylformamide, 3-aminopropanol and ethanol, and the volume ratio of N,N-dimethylformamide, ethanol and 3-aminopropanol is (1-3):(1-3):(1-3), for example, it can be 2:1:1, 2:1:2 or 1:3:1, etc.

[0040] In the present invention, in the step of obtaining a solid product by reacting at 70 to 90° C., the reaction time is 20 to 80 hours, more preferably 20 to 50 hours. The reaction is preferably carried out in a reactor.

[0041] In the present invention, after the reaction is completed, the reaction product is further washed and dried to obtain a solid product. The present invention does not impose any particular restrictions on the washing and drying steps, and the washing and drying steps commonly used in the art can be used.

[0042] In the present invention, in the vacuum activation step, the vacuum degree is 10 -7 mbar or less, the temperature is 120-170℃, the vacuum drying time is 5-15h, and the vacuum activation step is to remove the residual solvent molecules and gas molecules in the pores.

[0043] In the present invention, the preparation method of the triimidazole borohydride compound is as follows: potassium borocyanide and 2-methylimidazole are mixed in a second solvent, and a melting reaction is carried out at 200-230° C. to obtain the triimidazole borohydride compound. The molar ratio of potassium borocyanide to 2-methylimidazole is 1:(3-3.5), more preferably 1:(3.1-3.3); the reaction time of potassium borohydride and 2-methylimidazole is 3-8 hours.

[0044] The present invention also provides the use of the imidazole boron framework material in the separation of acetylene and carbon dioxide mixed gas. The imidazole boron framework material prepared by the present invention has a selectivity of acetylene / carbon dioxide of more than 3.9.

[0045] The technical solution of the present invention is further described below in conjunction with specific embodiments. In the following embodiments, the preparation method of the organic ligand potassium triimidazole borohydride (KHB(mim)3) is as follows: potassium borocyanide and 2-methylimidazole in a molar ratio of 1:3.1 are mixed and heated and stirred at 215°C for 4 hours to obtain the organic ligand KHB(mim)3.

[0046] Example 1

[0047] This embodiment provides an imidazole boron framework material BIF-24 (Cl - ) preparation method.

[0048] S1, dissolving zinc chloride, 0.6 g of organic ligand KHB(mim)3, 2-imidazolidinone and trimesic acid in a molar ratio of 1:0.48:11.62:0.48 in a mixed solvent of 20 mL of N,N-dimethylformamide, 10 mL of ethanol and 10 mL of 3-aminopropanol to form a mixed solution;

[0049] S2. Add the mixed solution obtained in step S1 into a 100 mL reactor and heat at 80° C. for 24 h.

[0050] S3, after the reaction kettle cools to room temperature, wash it alternately with deionized water and anhydrous ethanol three times, and dry it to obtain a white powder;

[0051] S4, the white powder obtained in step S3 is placed in a vacuum of 10 -7 mbar, 150°C vacuum conditions for 10 h to obtain imidazole boron framework material BIF-24 (Cl - ).

[0052] Figure 1 a is the imidazole boron framework material BIF-24 (Cl - ) scanning electron microscope image. As can be seen from the figure, BIF-24 (Cl - ) The imidazole boron framework material is mainly composed of rhombic dodecahedron. Figure 2a is the imidazole boron framework material BIF-24 (Cl - ) showed that the imidazole boron framework material BIF-24 (Cl - ) was successfully synthesized.

[0053] Example 2

[0054] This embodiment provides an imidazole boron framework material BIF-24 (OH - ) preparation method.

[0055] S1, dissolving zinc hydroxide, 0.6 g of organic ligand KHB(mim)3, 2-imidazolidinone and trimesic acid in a molar ratio of 1:0.48:11.62:0.48 in a mixed solvent of 20 mL of N,N-dimethylformamide, 10 mL of ethanol and 10 mL of 3-aminopropanol to form a mixed solution;

[0056] S2. Add the mixed solution obtained in step S1 into a 100 mL reactor and heat at 80° C. for 24 h.

[0057] S3, after the reaction kettle cools to room temperature, wash it alternately with deionized water and anhydrous ethanol three times, and dry it to obtain a white powder;

[0058] S4, the white powder obtained in step S3 is placed in a vacuum of 10 -7 mbar, 150°C vacuum conditions for 10 h to obtain imidazole boron framework material BIF-24 (OH - ).

[0059] Figure 1 b is the imidazole boron framework material BIF-24 (Cl - ) is a scanning electron microscope image. As can be seen from the figure, BIF-24(OH - ) The imidazole boron framework material is mainly spherical. Figure 2 b is the imidazole boron framework material BIF-24 (OH - ) showed that the imidazole boron framework material BIF-24(OH - ) was successfully synthesized.

[0060] Example 3

[0061] This embodiment provides an imidazole boron framework material BIF-24 (OH - ) preparation method.

[0062] S1, dissolving zinc hydroxide, 0.6 g of organic ligand KHB(mim)3, 2-imidazolidinone and trimesic acid in a molar ratio of 1:0.48:11.62:0.48 in a mixed solvent of 20 mL of N,N-dimethylformamide, 10 mL of ethanol and 20 mL of 3-aminopropanol to form a mixed solution;

[0063] S2. Add the mixed solution obtained in step S1 into a 100 mL reactor and heat at 80° C. for 24 h.

[0064] S3, after the reaction kettle cools to room temperature, wash it alternately with deionized water and anhydrous ethanol three times, and dry it to obtain a white powder;

[0065] S4, the white powder obtained in step S3 is placed in a vacuum of 10 -7 mbar, 150°C vacuum conditions for 10 h to obtain imidazole boron framework material BIF-24 (OH - ).

[0066] Example 4

[0067] This embodiment provides an imidazole boron framework material BIF-24 (OH - ) preparation method.

[0068] S1, dissolving zinc hydroxide, 0.6 g of organic ligand KHB(mim)3, 2-imidazolidinone and trimesic acid in a molar ratio of 1:0.48:11.62:0.48 in a mixed solvent of 10 mL of N,N-dimethylformamide, 30 mL of ethanol and 10 mL of 3-aminopropanol to form a mixed solution;

[0069] S2. Add the mixed solution obtained in step S1 into a 100 mL reactor and heat at 80° C. for 30 h.

[0070] S3, after the reaction kettle cools to room temperature, wash it alternately with deionized water and anhydrous ethanol three times, and dry it to obtain a white powder;

[0071] S4, the white powder obtained in step S3 is placed in a vacuum of 10 -7 mbar, 150°C vacuum conditions for 10 h to obtain imidazole boron framework material BIF-24 (OH - ).

[0072] Example 5

[0073] This embodiment provides an imidazole boron framework material BIF-24 (OH - ) preparation method.

[0074] S1, dissolving zinc hydroxide, 0.6 g of organic ligand KHB(mim)3, 2-imidazolidinone and trimesic acid in a molar ratio of 1:0.4:11:0.4 in a mixed solvent of 20 mL of N,N-dimethylformamide, 10 mL of ethanol and 20 mL of 3-aminopropanol to form a mixed solution;

[0075] S2. Add the mixed solution obtained in step S1 into a 100 mL reactor and heat at 80° C. for 24 h.

[0076] S3, after the reaction kettle cools to room temperature, wash it alternately with deionized water and anhydrous ethanol three times, and dry it to obtain a white powder;

[0077] S4, the white powder obtained in step S3 is placed in a vacuum of 10 -7 mbar, 150°C vacuum conditions for 10 h to obtain imidazole boron framework material BIF-24 (OH - ).

[0078] Comparative Example 1

[0079] This embodiment provides an imidazole boron framework material BIF-24 (NO3 - ) preparation method.

[0080] S1, dissolving zinc nitrate, 0.6 g of organic ligand KHB(mim)3, 2-imidazolidinone and trimesic acid in a molar ratio of 1:0.48:11.62:0.48 in a mixed solvent of 20 mL of N,N-dimethylformamide, 10 mL of ethanol and 10 mL of 3-aminopropanol to form a mixed solution;

[0081] S2. Add the mixed solution obtained in step S1 into a 100 mL reactor and heat at 80° C. for 24 h.

[0082] S3, after the reaction kettle cools to room temperature, wash it alternately with deionized water and anhydrous ethanol three times, and dry it to obtain a white powder;

[0083] S4, the white powder obtained in step S3 is placed in a vacuum of 10 -7 mbar, 150 ° C vacuum conditions for 10 hours, the imidazole boron framework material BIF-24 (NO3 - ).

[0084] Test example

[0085] 1. Determination of adsorption performance:

[0086] Figure 3 The imidazole boron framework material BIF-24 (Cl -) Single component adsorption curves of acetylene (a) and carbon dioxide (b) at different temperatures; Figure 3 As shown, the activated BIF-24 (Cl - ) has an adsorption capacity of 3.17 mmol / g for acetylene at room temperature and pressure (298 K, 1 bar), which is higher than its adsorption capacity for carbon dioxide (2.11 mmol / g).

[0087] Figure 4 The imidazole boron framework material BIF-24 (OH - ) Single component adsorption curves of acetylene (a) and carbon dioxide (b) at different temperatures; Figure 4 As shown, at room temperature and pressure (298K, 1 bar), the activated BIF-24 (OH - ) The adsorption capacity of acetylene reached 2.14mmol / g, while the adsorption capacity of carbon dioxide was 1.51mmol / g. Figure 7 As shown, BIF-24 (Cl - ) and BIF-24(OH - ) At room temperature and pressure, the gas adsorption ratios of acetylene and carbon dioxide are 1.50 and 1.41 respectively.

[0088] 2. Acetylene / carbon dioxide selectivity test:

[0089] Figure 5 The imidazole boron framework material BIF-24 (Cl - (a) The imidazole boron framework material BIF-24 (OH - ) (b) and BIF-24 (NO3 of Comparative Example 1 - )(c) The selectivity of acetylene / carbon dioxide calculated by ideal adsorption solution theory at different temperatures; The selectivity of BIF-24(Cl - ) has a selectivity of 4.15 for acetylene / carbon dioxide at 298K and 1 bar, and BIF-24(OH - ) has a selectivity of 3.92 for acetylene / carbon dioxide at 298K and 1 bar, while BIF-24 (NO3 - ) has an acetylene / carbon dioxide selectivity of 3.71.

[0090] Figure 6 The imidazole boron framework material BIF-24 (Cl - (a) The imidazole boron framework material BIF-24 (OH - )(b) The ratio of the gas adsorption of acetylene and carbon dioxide. At the initial pressure, BIF-24(Cl -) and BIF-24(OH - ) significantly increased the adsorption ratio of acetylene to carbon dioxide. At 298K, 0.005bar, BIF-24(Cl - ) and BIF-24(OH - ) have an adsorption ratio of acetylene to carbon dioxide of 7.02 and 7.91 respectively. As the pressure increases, the ratio decreases rapidly and drops to 1.50 and 1.41 at 1 bar.

[0091] 3. Fixed bed penetration test:

[0092] The activated BIF-24 (Cl - ) and BIF-24 (OH - ) was loaded into an adsorption column with an inner diameter of 4 mm, and a mixed gas of acetylene and carbon dioxide (volume ratio 50:50) was passed into the bed of the adsorption column at room temperature and atmospheric pressure (298K, 1 bar) at a rate of 5 mL / min to conduct a fixed bed penetration experiment. Figure 7 As shown in (a), when the acetylene / carbon dioxide mixture enters the BIF-24 (Cl - ) bed, carbon dioxide first broke through the bed at 10.90 minutes, and acetylene did not break through the bed until 34.33 minutes, and the separation time was about 23.43 minutes. Figure 7 As shown in (b), when the acetylene / carbon dioxide mixture enters the BIF-24 (OH - ) bed, carbon dioxide first broke through the bed at 2.97 minutes, and acetylene began to break through the bed at 13.90 minutes, and the separation time was about 10.93 minutes. The fixed bed penetration experiment proved that the BIF-24 (Cl - ) and BIF-24(OH - ) has good acetylene / carbon dioxide separation characteristics.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An imidazole boron framework material, characterized in that: It is assembled by coordination of metal zinc ions and triimidazole boron hydride compounds, and the free anion of the imidazole boron framework material is Cl - or OH - .

2. The imidazole boron framework material according to claim 1, characterized in that: The triimidazole borohydride compound is obtained by reacting potassium borocyanide and 2-methylimidazole.

3. The method for preparing the imidazole boron framework material according to any one of claims 1 to 2, characterized in that: The steps include: Dissolve zinc chloride or zinc hydroxide, triimidazole borohydride compound, 2-imidazolidinone and trimesic acid in a solvent, react at 70-90° C. to obtain a solid product, and then activate the solid product in vacuum to obtain the product.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the zinc chloride or zinc hydroxide, the triimidazole borohydride compound, 2-imidazolidinone and trimesic acid is 1:(0.3-0.6):(10-15):(0.3-0.6); the dosage ratio of the triimidazole borohydride compound to the solvent is (0.5-0.7) g:(30-70) mL.

5. The preparation method according to claim 3, characterized in that: The solvent is selected from a mixed solvent of N,N-dimethylformamide, 3-aminopropanol and ethanol, and the volume ratio of N,N-dimethylformamide, 3-aminopropanol and ethanol is (1-3):(1-3):(1-3).

6. The preparation method according to claim 3, characterized in that: In the step of obtaining a solid product by reacting at 70 to 90° C., the reaction time is 20 to 80 hours.

7. The preparation method according to claim 3, characterized in that: After the reaction is completed, the steps of washing and drying the reaction product are further included to obtain a solid product; in the vacuum activation step, the vacuum degree is 10 -7 mbar or less, the temperature is 120-170℃, and the time is 5-15h.

8. The preparation method according to claim 3, characterized in that: The preparation method of the triimidazole borohydride compound is as follows: potassium borocyanide and 2-methylimidazole are mixed in a second solvent, and a melting reaction is carried out at 200-230° C. to obtain the triimidazole borohydride compound.

9. The preparation method according to claim 8, characterized in that: The molar ratio of potassium borocyanide to 2-methylimidazole is 1:(3-3.5); the reaction time of potassium borohydride and 2-methylimidazole is 3-8 hours.

10. Use of the imidazole boron framework material according to any one of claims 1 to 2 or the imidazole boron framework material prepared by the preparation method according to any one of claims 3 to 9 in separation of acetylene and carbon dioxide mixed gas.

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