KR101339846B1 - The improved preparation method of porous metal organic framework - Google Patents

Abstract

According to the present invention, the porous metal-organic frameworks synthesized by conventionally optimizing the water content of the solvent when the pores have a hydrophilic or hydrophobic property and have a large pore size of the porous metal-organic framework (MOF) A method for producing metal-organic frameworks having a higher surface area and higher synthetic yields. The porous metal-organic framework synthesized through the improved method for producing a porous metal-organic framework according to the present invention can be applied to gas storage, catalyst, and sensor fields.

Description

The improved preparation method of porous metal organic framework

The present invention relates to a method for producing a porous metal-organic framework (MOF) having high surface area and high synthetic yield. More particularly, the present invention relates to an improved method for preparing a porous metal-organic framework, in which the pores have hydrophilic or hydrophobic properties, and in which a certain amount of water is added in the production of a porous metal-organic framework having a large pore size.

 Porous metal-organic frameworks (MOFs) are nanoporous bodies with very well defined pore sizes, as well as very high surface area, pore volume and rigid structure. In addition, by selecting an appropriate organic linker, that is, a bidentate compound, the pore size and chemical environment within the pore can be easily controlled, and are excellent in heat resistance and chemical resistance. The porous metal-organic framework consists of a metal oxide cluster and an organic linker, and the coordination structure formed from these metal ion moieties and organic ligands is linear as well as simple molecular form through self-assembly. Various skeletal structures can be formed, ranging from primary, plate-shaped secondary, and complex three-dimensional structures. The general synthesis method uses polar solvents (water, alcohol, acetone, acetonitrile, N-Methylpyrrolidone, dimethylforamide, diethylforamide, chlorobenzene, dimethylsulfoxide, chloroform, etc.) to dissolve the precursors of each component in an appropriate concentration, and put in a sealed container and heated Solvent thermal synthesis method is a typical method that is synthesized by the pressure generated by itself.

In addition to the Solvothermal method of dissolving each unit constituting the porous metal-organic framework in an appropriate solvent and reacting at high temperature and high pressure to form a framework, there are other solvents that can lower the solubility in the solvent in which the monomer is dissolved. The vapor diffusion method, which diffuses and penetrates, and the layer diffusion method, which forms a layer between two solutions containing different precursors and causes diffusion between the two layers to form a framework. It is used. However, the conventional methods for producing a porous metal-organic skeleton are a method in which a precursor of a metal component and a precursor of an organic component are dissolved in a suitable solvent to form a skeleton through self-assembly. Unreacted products such as water, solvents added to dissolve precursors, unreacted precursor materials themselves, monomers, oligomers by reaction between metal precursors and organic precursors, and reaction by-products exist in the pores (including channels) in the body. Causes a decrease. It is important to make metal-organic frameworks with high surface areas and clean three-dimensional pores for use in gas (methane, carbon dioxide, hydrogen, etc.) storage, catalysts, and sensors.

In addition, the porous metal-organic skeleton obtained after the synthesis according to the ratio of the metal oxide cluster and the organic linker in the preparation of the porous metal-organic framework, the type of solvent used in the synthesis, the manufacturing temperature, etc. The shape and yield of the sieves vary. Therefore, it is important to optimize the proportion of reactants and the production conditions for each porous metal-organic framework.

Eddaoudi et al., Science 295 (2002), 469-472, relating to the preparation of porous metal-organic frameworks, for example, describe the preparation of MOF-5 from zinc salts, ie zinc nitrate. In the synthesis of MOF, the salt and 1,4-benzenedicarboxylic acid (BDC) are dissolved in N, N-diethylformamide (DEF). In Chen et al., Science 291 (2001), 1021-1023, for example, copper salts (copper nitrate) are used as starting materials, the salts and 4,4 ', 4 "-benzene-1,3 The preparation of MOF-14 is described in which, 5-triyltribenzoic acid (H3BTC) is dissolved in N, N-dimethylformamide (DMF) and water to synthesize MOF. Korean Patent Laid-Open Publication No. 10-2009-0031358) discloses a method for preparing a porous metal-organic framework comprising two or more organic compounds coordinated to one or more metal ions.

The above production methods are production methods that can be used when the length of the organic linking group is short and the organic linking group has no functional group. In the case where the length of the organic linking group serving as a linker of the metal-organic framework is increased and the pores are large and there are hydrophilic functional groups, there may be the following problems. As the length of the organic linking group becomes longer, the two metal-organic frameworks may be twisted together to cause interpenetration, leading to a reduction in surface area, and due to the functional groups present in the organic ligand, unreacted solvents or unreacted substances in the pores. Reaction by-products can be formed with unreacted materials such as monomers, oligomers, and the like by the reaction between the precursor material itself, the metal precursor and the organic precursor, resulting in a reduction of yields due to the residue blocking the micropores.

Accordingly, the present inventors have made great efforts to improve a method for preparing a metal-organic framework having a particularly strong hydrophilic property in which the pores have hydrophilicity or hydrophobicity and a large pore size (20 μs or more). The condition of adding ˜0.3% by weight of water was established. Through the above method, it was confirmed that the preparation of the metal-organic framework has a higher surface area and higher yield than that of the conventional manufacturing method.

Republic of Korea Patent Publication 10-2009-0031358 (2009.03.25)

 Eddaoudi et al., Science 295 (2002), 469-472  Chen et al., Science 291 (2001), 1021-1023

The present invention relates to a method for producing a metal-organic framework, particularly when the pores of the porous metal-organic framework have hydrophilicity or hydrophobicity, and have a large pore size (20 μs or more). It is an object to provide a method for producing a metal-organic skeleton having high surface area and yield by optimizing the water content of the solvent by using water in addition to the organic solvent in preparing the organic framework.

The present invention is to solve the problems in the preparation of the metal-organic framework when the pores of the porous metal-organic skeleton has hydrophilic or hydrophobic properties and the pore size is large (20Å or more), the porous having a high surface area Allows stable and rapid mass production of metal-organic frameworks, unreacted materials (metal oxide cluster precursors, organic linker precursors), reaction byproducts (poly (carboxylic acids) that may be present inside the pores in connection with the preparation of porous metal-organic frameworks It provides a method to increase the yield by reducing the oligomer, a polymer material prepared by using an organic linking group as a monomer).

When using the conventional manufacturing method, it is difficult to realize a high surface area when synthesizing a metal-organic framework having pores having hydrophilicity or hydrophobicity, particularly having high hydrophilicity and a large pore size (20 μs or more), and yields are remarkably high. I could see it falling.

The present inventors solved this problem by optimizing the water content of the solvent by using water in addition to the organic solvent in the preparation of the porous metal-organic framework.

 The present invention provides a method for preparing a porous metal-organic framework as follows:

1) dissolving a metal salt and an organic ligand precursor in which the metal ions of Groups 1 to 16 and the anions of Groups 14 to 17 are bonded to a mixed solvent of an organic solvent and water to form a porous metal-organic framework;

2) a solvent exchange step of dipping the porous metal-organic framework in a first solvent;

3) continuous mixed supercritical treatment of the washed porous metal-organic framework using supercritical carbon dioxide (CO ₂ ) and a second solvent; And

4) drying the continuous mixed supercritical treated porous metal-organic framework at high temperature under reduced pressure.

Hereinafter, the step of preparing the porous metal-organic framework of the present invention will be described in detail.

Step 1 dissolving the metal salt and the organic ligand precursor compound in a mixed solvent of an organic solvent and water to form a porous metal-organic framework

The synthesis of the porous metal-organic framework of step 1) follows a well-known conventional manner, but is prepared by the reaction of a metal ion compound and an organic ligand in a mixed solvent of an organic solvent and water. The metal ion of the metal ion compound used at this time includes from Group 1 to Group 16, Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Be ^{2 +} , Mg ^{2 +} , Ca ^{2 +} , Sr ^{2 +} , Ba ^{2 +} , Sc ^{3 +} , Y ^{3 +} , Ti ^{4 +} , Zr ^{4 +} , Hf ⁺ , V ⁴⁺ , V ^{3 +} , V ^{2 +} , Nb ^{3 +} , Ta ^{3 +} , Cr ^{3 +} , Mo ^{3 +} , W ^{3 +, Mn 3 +, Mn 2} +, Re 3 +, Re 2 +, Fe 3 +, Fe 2 +, Ru 3 +, Ru 2 +, Os 3 +, Os 2 +, Co 3 +, Co 2 +, Rh ^{2 +} , Rh ⁺ , Ir ^{2 +} , Ir ⁺ , Ni ^{2 +} , Ni ⁺ , Pd ^{2 +} , Pd ⁺ , Pt ^{2 +} , Pt ⁺ , Cu ^{2 +} , Cu ⁺ , Ag ⁺ , Au ⁺ , Zn ^{2 +, Cd 2 +, Hg 2} +, Al 3 +, Ga 3 +, In 3 +, Tl 3 +, Si 4 +, Si 2 +, Ge 4 +, Ge 2 +, Sn 4 +, Sn 2 +, ^{Pb 4 +, Pb 2 +,} As 5 +, As 3+, As +, Sb 5 +, Sb 3 +, Sb +, Bi 5 +, Bi 3 + , and one or more selected from the Bi ⁺ Be sure to participate in the reaction. The metal ion compound may be in the form of a metal salt, and the anion that binds to the metal ion in the metal salt is a conventional anion, preferably an anion belonging to Group 14 to Group 17, and the metal salt includes metal nitrate, metal sulfate, metal phosphate, Metal inorganic salts, such as a metal hydrochloride, can be mentioned, but is not limited to these.

The organic solvent is acetone, acetonitrile, benzene, butanol, carbon tetrachloride, chloroform, methylene chloride cyclohexane, dime Methoxyethane, dimethylforamide, diethylforamide, dioxane, methanol, ethanol, ether, ethyl acetate, Ethylene glycol, glycerine, pentane, hexane, heptane, methyl tertiary butyl ether (MTBE), propanol, xylene ), t-butyl alcohol, one or two or more solvents selected from tetrahydrofuran and toluene may be used, and preferably dimethylforamide may be used..

The water is contained in an amount of 0.01 to 0.3% by weight, preferably 0.1 to 0.3% by weight based on the total mixed solvent of the organic solvent and water. When the content of water is less than 0.1% by weight, there is a problem that the synthetic yield falls, and when the content of water exceeds 0.3% by weight, the specific surface area value is very low. In order to raise specific surface area, it is good to use in the said range.

In the case of an organic ligand that serves as an intermetallic link ring of the porous metal-organic framework, the organic ligand has two or more functional groups capable of bonding with metal ions, for example, dicarboxylate. The organic ligand used here is an aromatic hydrocarbon having a carboxylic acid, and the pore size and shape of the metal-organic framework can be determined by the size and shape of the organic ligand. The shape of the metal-organic framework and the size of the pores, the hydrophilicity or hydrophobicity of the pores are determined by the use of the organic ligand precursor compound having the following structure, but the present invention is not limited to the following examples.

[Wherein R ₁ to R ₄₆ are independently of each other H, OH, NH ₂ , NHR ', NHR'R ", SH, SR', SOOH, SOOOH, PH ₂ , POOH ₂ , PHR 'or PR'R"; R 'and R "are each (C1-C3) alkyl except where R ₁ to R ₄ are all hydrogen.]

It is preferable that the said organic ligand precursor compound is an organic ligand precursor compound which has the following structure.

<Step 2> Solvent exchange step of immersing the porous metal-organic skeleton in the first solvent

In the solvent exchange step of step 2), the first solvent is contacted with the porous metal-organic framework to extract and remove water and organic solvent present in the pores of the porous metal-organic framework from the metal-organic framework. In this case, a solvent different from the organic solvent of step 1) is used, and a solvent having a high miscibility with the organic solvent of step 1) and having a lower boiling point than the organic solvent of step 1) is used. The solvent exchange is performed by leaving the synthesized porous metal-organic skeleton in the first solvent for a predetermined time. The solvent exchange time is preferably 12 hours to 72 hours. If the solvent exchange time exceeds 72 hours, the pore structure of the metal-organic framework collapses and the surface becomes narrow. If the solvent exchange time is less than 12 hours, the residue present in the pores cannot be sufficiently removed. More preferably, 24 hours to 48 hours are preferable. At this time, the first solvent used is acetone, acetonitrile, benzene, butanol, butanol, carbon tetrachloride, chloroform, methylene chloride cyclohexane ), Dimethoxyethane, dimethylformamide, dimethylformamide, diethylforamide, dioxane, methanol, methanol, ethanol, ether, ethyl acetate ethyl acetate, ethylene glycol, glycerin, pentane, hexane, heptane, methyl tertiary butyl ether (MTBE), propanol, One or two or more solvents selected from xylene, t-butyl alcohol, tetrahydrofuran, toluene and water may be used, preferably in step 1). Dimethyl Foam as Organic Solvent In the case of using amide, the first solvent may be chloroform.

<Step 3> Continuous mixed supercritical treatment of the porous metal-organic framework

Continuous mixing supercritical treatment of the porous metal-organic framework in step 3) is a supercritical treatment by mixing a supercritical carbon dioxide and a second solvent for a predetermined time using a continuous supercritical processing apparatus.

The supercritical treatment method is to use the same method as the continuous supercritical carbon dioxide treatment method described in the patent application (Korean Patent Publication No. 10-2010-0125771) by the applicant. However, in the supercritical processing method described in the patent application, the phenomenon of pore collapse due to foreign substances present in the metal-organic framework due to the polarity of the second solvent occurs, so that the characteristics of the pore are hydrophilic and the pore size is 20Å. It is difficult to completely remove the pore residue of the large metal organic framework without structural collapse. Therefore, in the present invention, a continuous mixed supercritical mixture of existing supercritical carbon dioxide and a second solvent having good miscibility with the first solvent and a lower boiling point than the organic solvent of step 1). A treatment method was developed. The continuous mixed supercritical treatment method of the present invention is more effective as the metal-organic framework having a strong hydrophilic property and a large pore size. In the continuous mixed supercritical treatment method, the supercritical carbon dioxide is continuously flowed into the porous metal-organic framework, while the second solvent and the supercritical carbon dioxide are flowed simultaneously after a predetermined time, thereby remaining in the porous metal-organic framework. It is a way to remove water. That is, supercritical carbon dioxide is started to be supplied to the porous metal-organic framework to remove some foreign substances in the metal-organic framework, and then the second solvent is supplied simultaneously with the supercritical carbon dioxide to continuously mix supercritical treatment.

In this case, the second solvent used is acetone, acetonitrile, benzene, butanol, butanol, carbon tetrachloride, chloroform, methylene chloride, cyclohexane ), Dimethoxyethane, dimethylformamide, dimethylformamide, diethylforamide, dioxane, methanol, methanol, ethanol, ether, ethyl acetate ethyl acetate, ethylene glycol, glycerin, pentane, hexane, heptane, methyl tertiary butyl ether (MTBE), propanol, One or more solvents selected from xylene, t-butyl alcohol, tetrahydrofuran, toluene and water can be used, and preferably as the first solvent. Using chloroform In the case of the second solvent chloroform (chloroform) is used.

If the supply time of the second solvent is too long, the pore structure of the porous metal-organic framework collapses, and the residue is not completely removed. In addition, too high an hourly dose of the second solvent also causes a problem of structural collapse and too slow a problem that the residue is not completely removed. In addition, when the supply time of the second solvent is longer than or equal to the supply time of the supercritical carbon dioxide, a problem occurs in that the second solvent remains in the pores of the porous metal-organic framework to narrow the surface area. For the above reasons, the second solvent is supplied for 1 to 6 hours at a flow rate of 1 to 10 ml / min, and preferably for 3 to 4 hours at a flow rate of 3 to 6 ml / min.

The total feed flow rate of supercritical carbon dioxide supplied to the porous metal-organic framework is 0.001-20 ml / min. 5 to 15 hours at a flow rate, more preferably 0.1 to 10 ml / min. Feed for 6-8 hours at flow rate. If the flow rate of the supercritical carbon dioxide is too fast, a problem may occur that removes residues in the pores and disrupts the structure of the pores. If the flow rate of the supercritical carbon dioxide is too slow, the residues in the pores may not be completely removed. The problem remains that the solvent remains in the pores to narrow the surface area.

When supercritical carbon dioxide and a second solvent are simultaneously fed into a closed reactor and mixed inside the reactor, the pressure and temperature of the carbon dioxide before being fed into the reactor are the pressure and temperature (31.1 to 80 ° C., 72.9 to 250 bar) that satisfy the supercritical conditions. If supercritical carbon dioxide and the second solvent are mixed in the reactor, the carbon dioxide pressure and temperature just before feeding to the reactor, the pressure and temperature of the second solvent just before feeding to the reactor, the porous metal-organic in the reactor The discharge flow rate of the activating fluid (containing the second solvent and supercritical carbon dioxide) discharged after contact with the framework and the temperature of the reactor controlled by the temperature control device (including the temperature sensor, heater and controller) provided in the reactor. The temperature and pressure at the time of activation of the porous metal-organic framework, ie the temperature and pressure inside the reactor, are controlled.

Step 4 drying at high temperature and reduced pressure

Step 4) is a drying process of the porous metal-organic framework in which the continuous mixed supercritical treatment of step 3) is completed, and is not completely removed even after the solvent exchange of step 2) and the continuous mixed supercritical process of step 3). Drying the porous metal-organic framework for a period of time under reduced pressure at high temperature to remove the residues.

The supercritical treated porous metal-organic framework is dried by applying a pressure of 0.1 to 0.01 torr for 3 to 10 hours while heating to a temperature of 100 to 300 ° C. More preferably, it is dried by applying a pressure of 0.05 to 0.01 torr (torr) for 5 to 6 hours while heating to 130 to 200 ℃. In this case, when the temperature exceeds 300 ° C., the structural stability of the metal-organic skeleton having poor thermal stability may occur, resulting in a narrow surface area. When the temperature is less than 100 ° C., residues remaining in pores may not be completely removed. There is a problem. In addition, when the reduced pressure exceeds 0.1 torr (torr), the residue is not completely removed, if less than 0.01 torr (torr) may cause the structure of the pores collapse.

Since the porous metal-organic framework prepared by the four-step manufacturing method according to the present invention has a specific surface area of 5000 m ² / g or more, it can be applied to adsorbents or storage agents of fine molecules such as carbon dioxide, methane or hydrogen.

The porous metal-organic skeleton prepared by the production method according to the present invention has a long organic linking group having a large pore size (more than 20Å), and a metal-organic framework and various materials using functional groups present in the organic linking group. Reaction is possible. In addition, it is possible to implement a higher specific surface area and yield compared to the conventional method for producing a metal-organic framework can be useful in the field of gas storage, catalyst, sensor, ion exchange.

1-PXRD results of Examples 1-3, Comparative Examples 1-3 and IRMOF16
2-Hydrogen adsorption measurement results of Examples 1 to 3 and Comparative Examples 1 to 3

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail. However, this description is intended to be easily carried out by those skilled in the art, the scope of the present invention is not limited thereto.

[ Example ]

All chemicals and solvents used in the examples of the present invention were used as reagent grade without further purification. Synthesis of the metal-organic framework was synthesized by a conventional solvothermal method, and synthesized in a dry box under argon gas without moisture for accuracy of moisture control during synthesis.

[ Example  One] Zn ₄ O ( C ₂₀ H ₁₂ O ₆ ) ₃  of  Produce

Zinc nitrate salt (Zn (NO ₃ ) ₂ 6H ₂ O) (2.23 g) and organic ligand precursor B (0.35 g) were added to dimethylformamide (DMF) (200 mL) in a 250 ml flask. After dissolving in the solvent for synthesis, it was placed in an 85 ℃ oven for 80 hours. As a result, a brown solid formed, which were filtered off and washed with DMF. After transferring the formed brown metal-organic framework into a 250ml flask, injecting 200ml of chloroform (CHCl ₃ ), and leaving it for 48 hours for solvent exchange, and then transferring the solvent-exchanged metal-organic framework to a supercritical vessel. Supercritical treatment (supercritical carbon dioxide + chloroform mixture) was performed. Supercritical carbon dioxide 10ml / min. After treating for 6 hours at a flow rate, a mixed solvent of supercritical carbon dioxide and chloroform was 3 ml / min. Treatment was carried out for 3 hours at flow rate. The supercritical treated metal-organic framework was transferred to a reduced pressure vessel and subjected to reduced pressure at 200 ° C. for 6 hours to give the title porous metal-organic framework Zn ₄ O (C ₂₀ H ₁₂ O ₆ ) ₃ Was prepared (yield 38.2%).

Anal. Calc. for Zn ₄ O (C ₂₀ O ₆ H ₁₂ ) ₃ : C, 54.49; H, 2. 74; 0, 22.99; Zn, 19.78

Found: C, 54.42; H, 2.71, Zn, 19.80

[ Example  2] Zn ₄ O ( C ₂₀ H ₁₂ O ₆ ) ₃  of  Produce

Zinc nitrate salt (Zn (NO ₃ ) ₂ 6H ₂ O) (2.23 g) and organic ligand precursor B (0.35 g) were added to dimethylformamide (DMF) (200 mL) in a 250 ml flask. After dissolving in the solvent for synthesis, it was placed in an 85 ℃ oven for 80 hours. As a result, a brown solid formed, which were filtered off and washed with DMF. After transferring the formed brown metal-organic framework into a 250ml flask, injecting 200ml of chloroform (CHCl ₃ ), and leaving it for 48 hours for solvent exchange, and then transferring the solvent-exchanged metal-organic framework to a supercritical vessel. Supercritical treatment (supercritical carbon dioxide + chloroform mixture) was performed. Supercritical carbon dioxide 10ml / min. The mixture was treated for 6 hours at a flow rate and a mixed solvent of supercritical carbon dioxide and chloroform was 3 ml / min. Treatment was carried out for 3 hours at flow rate. The supercritical treated metal-organic framework was transferred to a reduced pressure vessel and subjected to reduced pressure at 200 ° C. for 6 hours to give the title porous metal-organic framework Zn ₄ O (C ₂₀ H ₁₂ O ₆ ) ₃ Was prepared (yield: 35.2%).

[ Example  3] Zn ₄ O ( C ₂₀ H ₁₂ O ₆ ) ₃  of  Produce

Zinc nitrate salt (Zn (NO ₃ ) ₂ 6H ₂ O) (2.23 g) and organoligand precursor B (0.35 g) were added to dimethylformamide (DMF) (200 mL) in a 250 ml flask. After dissolving in the solvent for synthesis, it was placed in an 85 ℃ oven for 80 hours. As a result, a brown solid formed, which were filtered off and washed with DMF. After transferring the formed brown metal-organic framework into a 250ml flask, injecting 200ml of chloroform (CHCl ₃ ), and leaving it for 48 hours for solvent exchange, and then transferring the solvent-exchanged metal-organic framework to a supercritical vessel. Supercritical treatment (supercritical carbon dioxide + chloroform mixture) was performed. Supercritical carbon dioxide 10ml / min. The mixture was treated for 6 hours at a flow rate and a mixed solvent of supercritical carbon dioxide and chloroform was 3 ml / min. Treatment was carried out for 3 hours at flow rate. The supercritical treated metal-organic framework was transferred to a reduced pressure vessel and subjected to reduced pressure at 200 ° C. for 6 hours to give the title porous metal-organic framework Zn ₄ O (C ₂₀ H ₁₂ O ₆ ) ₃ Was prepared (yield: 36.6%).

[ Comparative Example  One] Zn ₄ O ( C ₂₀ H ₁₂ O ₆ ) ₃  of  Produce

In a 250 ml flask, zinc nitrate salt (Zn (NO ₃ ) ₂ 6H ₂ O) (2.23 g) and organic ligand precursor B (0.35 g) were dissolved in 200 ml of dimethylformamide (DMF) without adding water. Placed in an oven for 80 hours. As a result, a brown solid formed, which were filtered off and washed with DMF. After transferring the formed brown metal-organic framework into a 250ml flask, injecting 200ml of chloroform (CHCl ₃ ), and leaving it for 48 hours for solvent exchange, and then transferring the solvent-exchanged metal-organic framework to a supercritical vessel. Supercritical treatment (supercritical carbon dioxide + chloroform mixture) was performed. Supercritical carbon dioxide 10ml / min. The mixture was treated for 6 hours at a flow rate and a mixed solvent of supercritical carbon dioxide and chloroform was 3 ml / min. Treatment was carried out for 3 hours at flow rate. The supercritical treated metal-organic framework was transferred to a reduced pressure vessel and subjected to reduced pressure at 200 ° C. for 6 hours to give the title porous metal-organic framework Zn ₄ O (C ₂₀ H ₁₂ O ₆ ) ₃ Was prepared (yield: 11.3%).

[ Comparative Example  2] Zn ₄ O ( C ₂₀ H ₁₂ O ₆ ) ₃  of  Produce

Zinc nitrate salt (Zn (NO ₃ ) ₂ 6H ₂ O) (2.23 g) and organic ligand precursor B (0.35 g) were dissolved in a 250 ml flask in a synthetic solvent in which 0.79 g of water was added to 200 ml of dimethylformamide (DMF). After drying, the mixture was placed in an oven at 85 ° C. for 80 hours. As a result, a brown solid formed, which were filtered off and washed with DMF. After transferring the formed brown metal-organic framework into a 250ml flask, injecting 200ml of chloroform (CHCl ₃ ), and leaving it for 48 hours for solvent exchange, and then transferring the solvent-exchanged metal-organic framework to a supercritical vessel. Supercritical treatment (supercritical carbon dioxide + chloroform mixture) was performed. Supercritical carbon dioxide 10ml / min. The mixture was treated for 6 hours at a flow rate and a mixed solvent of supercritical carbon dioxide and chloroform was 3 ml / min. Treatment was carried out for 3 hours at flow rate. The supercritical treated metal-organic framework was transferred to a reduced pressure vessel and subjected to reduced pressure at 200 ° C. for 6 hours to give the title porous metal-organic framework Zn ₄ O (C ₂₀ H ₁₂ O ₆ ) ₃ Was prepared (yield: 25.7%).

[ Comparative Example  3] Zn ₄ O ( C ₂₀ H ₁₂ O ₆ ) ₃  of  Produce

Zinc nitrate salt (Zn (NO ₃ ) ₂ 6H ₂ O) (2.23 g) and organic ligand precursor B (0.35 g) were dissolved in a 250 ml flask in a synthetic solvent in which 0.95 g of water was added to 200 ml of dimethylformamide (DMF). After drying, the mixture was placed in an oven at 85 ° C. for 80 hours. As a result, a brown solid formed, which were filtered off and washed with DMF. After transferring the formed brown metal-organic framework into a 250ml flask, injecting 200ml of chloroform (CHCl ₃ ), and leaving it for 48 hours for solvent exchange, and then transferring the solvent-exchanged metal-organic framework to a supercritical vessel. Supercritical treatment (supercritical carbon dioxide + chloroform mixture) was performed. Supercritical carbon dioxide 10ml / min. The mixture was treated for 6 hours at a flow rate and a mixed solvent of supercritical carbon dioxide and chloroform was 3 ml / min. Treatment was carried out for 3 hours at flow rate. The supercritical treated metal-organic framework was transferred to a reduced pressure vessel and subjected to reduced pressure at 200 ° C. for 6 hours to give the title porous metal-organic framework Zn ₄ O (C ₂₀ H ₁₂ O ₆ ) ₃ Was prepared (yield: 28.0%).

The conditions and results of Examples 1 to 3 and Comparative Examples 1 to 3 are summarized in Table 1 below.

Examples 1 to 3, Comparative Examples 1 to 3 conditions and results Example
One Example
2 Example
3 Comparative Example
One Comparative Example
2 Comparative Example
3 Water content (wt%) 0.1 0.2 0.3 0 0.4 0.5 Solvent exchange O O O O O O Mixed Supercritical Treatment O O O O O O Decompression drying O O O O O O Organic ligand precursor B B B B B B Specific surface area
(BET, m ² / g) 5850 4900 4500 4300 2180 1200 Pore size 21.5 21.5 21.5 21.5 21.5 21.5 Yield (%) 38.2 35.2 36.6 11.3 25.7 28.0 Hydrogen storage amount (wt%) 1.2 1.08 1.03 1.0 0.78 0.62 * BET: Brunauer-Emmett-Teller surface area
* Hydrogen storage: hydrogen p / p0 = 1 at 77K

Physical property analysis

In order to characterize the porous metal-organic frameworks prepared according to Examples 1 to 3 and Comparative Examples 1 to 3, X-ray diffraction analysis (XRD), specific surface area measurement, and hydrogen storage amount were measured.

X-ray Diffraction analysis

The XRD data of Examples 1 to 3 and Comparative Examples 1 to 3 according to the present invention were compared with the data of IRMOF-16 having the same structure. The X-ray diffractometer was measured on Bruker D8 advanc under the following conditions: range: 3 to 60 ^o , step: 0.02 ^o , and step time: 1.2 s.

Specific surface area  Measure

Specific surface area analysis was performed to examine the specific surface area of the prepared metal-organic framework. It was measured using Autosorb-iQ (Quantachrome Instruments) and after pretreatment in vacuum at 200 ° C. for 3 hours. Using the Brunauer-Emmett-Teller equation (BET) method, the specific surface area was determined by N ₂ gas isotherm at 77K, and the range of P / P ₀ was 0.01 ~ 0.1.

Hydrogen storage measurement

Hydrogen adsorption characteristics of the prepared metal-organic framework were measured using Autosorb-iQ (Quantachrome Instruments). Hydrogen adsorption curves were determined by H ₂ gas isotherm at 77K, and the range of P / P ₀ was 0.1 ~ 1.

As shown in Table 1, it was confirmed that the metal-organic framework prepared by adding 0.1 wt% to 0.3 wt% of water by the method shown in the present invention has a high surface area and a high synthesis yield. When no water was added (Comparative Example 1), it was confirmed that the specific surface area was not high for mass production due to the high level of the specific surface yield, but the synthetic yield was remarkably low (Comparative Example 2 and Comparative Example 3). The synthesis yield was relatively high, but the specific surface area value was found to be very low.

The method of adding water in synthesizing the metal-organic framework through FIG. 1 (XRD data of IRMOF16 having the same structure as Examples 1 to 3 and Comparative Examples 1 to 3) affected the structure of the porous metal-organic framework. It was confirmed that it does not cause structural damage and structural collapse.

It was confirmed that the metal-organic framework prepared by the method for producing a metal-organic framework according to the present invention had the largest specific surface area with experimental values almost identical to the theoretically calculated specific surface area value. Theoretical specific surface area is based on the specific surface area of the metal-organic framework (IRMOF-16) (experimental value: 6070m ² / g) prepared from organic ligand precursor D and nitrite salt (Zn (NO ₃ ) ₂ 6H ₂ O). The results of calculating the specific surface area of 6225 m ² / g using the Monte Carlo intergration technique have been reported in the literature. Based on the literature, theoretical specific surface values of Examples 1 to 3 and Comparative Examples 1 to 3 having the same structure as IRMOF-16 were inferred.

In addition, the gas storage capacity of the porous metal-organic framework was confirmed through the results of FIG. 2 (the hydrogen storage measurement result of 1 to 3 compared with Examples 1 to 3). Examples 1 to 3 prepared by the method according to the present invention showed a result of adsorbing a relatively large amount of hydrogen due to the high specific surface area, it was confirmed that the hydrogen storage capacity of the Comparative Examples 1 to 3 is poor.

These results confirmed that the pores of the metal-organic framework prepared by the method proposed in the present invention were regularly arranged so that the specific surface area value was very high and yield was high. In addition, it is directly related to the gas storage capacity can be a great advantage for later use as a gas storage material.

Claims (16)

1) dissolving a metal salt and an organic ligand precursor in which a metal ion of Group 1 to 16 and an anion of Group 14 to 17 are bonded to a mixed solvent of an organic solvent and water to form a metal-organic framework;
2) a solvent exchange step of immersing the metal-organic framework in a first solvent;
3) continuous mixed supercritical treatment of the solvent-exchanged metal-organic framework using supercritical carbon dioxide (CO ₂ ) and a second solvent; And
4) drying the continuous mixed supercritical treated metal-organic skeleton at high temperature under reduced pressure.
The method of claim 1,
The organic solvent is acetone, acetonitrile, benzene, butanol, carbon tetrachloride, chloroform, methylene chloride cyclohexane, dimethoxyethane, dimethylformamide, diethylformamide, dioxane, methanol, ethanol, ether, ethyl acetate, ethylene One, two or more mixed solvents selected from the group consisting of glycol, glycerin, pentane, hexane, heptane, methyl t-butyl ether, methylene chloride, propanol, xylene, t-butyl alcohol, tetrahydrofuran and toluene Method for producing a porous metal-organic framework.
The method of claim 1,
The amount of water is 0.01 to 0.3% by weight based on the total mixed solvent, the method for producing a porous metal-organic skeleton.
The method of claim 1,
The pores of the porous metal-organic framework have a hydrophobic or hydrophilic property.
The method of claim 1,
The organic ligand precursor is a method for producing a porous metal-organic framework, characterized in that selected from the following structure.

[Wherein R ₁ to R ₄₆ are independently of each other H, OH, NH ₂ , NHR ', NHR'R ", SH, SR', SOOH, SOOOH, PH ₂ , POOH ₂ , PHR 'or PR'R"; R 'and R "are each (C1-C3) alkyl except where R ₁ to R ₄ are all hydrogen.]
6. The method of claim 5,
The organic ligand precursor compound is a method for producing a porous metal-organic framework, characterized in that selected from the following structure.

The method of claim 1,
The first solvent and the second solvent are acetone, acetonitrile, benzene, butanol, carbon tetrachloride, chloroform, methylene chloride cyclohexane, dimethoxyethane, dimethylformamide, diethylformamide, dioxane, methanol, ethanol, One, two or more mixed solvents selected from the group consisting of ether, ethyl acetate, ethylene glycol, glycerin, pentane, hexane, heptane, methyl t-butyl ether, propanol, xylene, t-butyl alcohol, tetrahydrofuran, toluene and water Method for producing a porous metal-organic skeleton, characterized in that.
The method of claim 1,
The organic solvent is dimethylformamide, the first solvent and the second solvent is chloroform, the method for producing a porous metal-organic framework.
The method of claim 1,
Method for producing a porous metal-organic skeleton, characterized in that at the same time supplying a second solvent after the start of supply of supercritical carbon dioxide in step 3).
The method of claim 9,
The supercritical carbon dioxide is supplied at a flow rate of 0.001 to 20 ml / min for 5 to 15 hours, and the second metal is supplied at a flow rate of 1 to 10 ml / min for 1 to 6 hours. Method of preparation.
The method of claim 1,
Step 4) is a method for producing a porous metal-organic skeleton, characterized in that performed for 3 to 10 hours at a temperature of 100 ~ 300 ℃ and a pressure of 0.01 ~ 0.1 torr.
The method of claim 1,
The porous metal-organic framework is a porous metal-organic skeleton manufacturing method characterized in that it has a pore of 20 or more.
A porous metal-organic framework, prepared by the method of any one of claims 1 to 12, characterized by a specific surface area of at least 5000 m ² / g.
The method of claim 13,
The porous metal-organic skeleton is characterized in that the porous metal-organic skeleton has a pore of 20 or more.
Adsorbent or storage agent of fine molecules using the porous metal-organic framework according to claim 13.
16. The method of claim 15,
The fine molecules are carbon dioxide, methane or hydrogen adsorbent or storage agent, characterized in that.

Images