Method for producing metal-organic framework

Abstract

To provide a method for producing Zn-MOF at low cost and within a short time.SOLUTION: A method for producing a metal-organic framework includes zinc ions coordinated with triazolates and oxalates optionally bearing substituents, where the method employs a zinc compound having a solubility of 0.05 g or more in 100 cm3 of water at 25°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a metal-organic framework.

Background Art

[0002] Capturing harmful greenhouse gases, particularly carbon dioxide (CO 2 2), from industrial waste can contribute to suppressing the global amount of carbon dioxide and is an important technology for countermeasures against global warming. Gas separation methods include membrane separation, adsorption separation, absorption separation, and cryogenic separation. The membrane separation method is a technique for separating gases based on the velocity difference of gases permeating through a membrane using pressure as the driving force. Since it hardly involves a phase change during gas separation, it consumes less energy compared to other gas separation methods. In recent years when global climate change demands the reduction of greenhouse gases, the membrane separation method with low energy consumption has attracted attention as an alternative to conventional separation techniques and a means for separating and recovering greenhouse gases.

[0003] Conventionally, activated carbon and zeolite have been representative as porous materials capable of adsorbing gases. In recent years, however, porous materials having nano-sized pores formed by coordination polymers constructed from metals and bridging ligands have attracted attention. For example, the adsorption of carbon dioxide using a metal-organic framework (Metal Organic Frameworks, hereinafter sometimes referred to as "MOF") as a porous material has been reported (Patent Document 1).

[0004] In the examples of Patent Document 1, as a method for manufacturing MOF, a method of mixing zinc oxalate, 1,2,4-triazole, water, and methanol and performing hydrothermal synthesis at 180°C for about 48 hours is disclosed. However, this method has room for improvement in that the synthesis temperature is high and the synthesis time is long, and it is not preferable in terms of economy either. Therefore, in Patent Document 2, the formula: Zn 2 Ht 2A method for preparing a Zn MOF of CL (wherein Ht is a combination of 1,2,4-triazole or 1,2,4-triazolato and one or more other cycloazacarbil compounds, and CL is a combination of oxalate or oxalate and one or more chelating ligands other than oxalate), comprising: (1) reacting said combination of 2 molar equivalents of 1,2,4-triazole or 1,2,4-triazolato and one or more other cycloazacarbil compounds with 1 molar equivalent of oxalate or a combination of oxalate and one or more chelating ligands other than oxalate to form a cycloazacarbil chelating ligand compound as a suspension in a solvent; and (2) adding 2 molar equivalents of Zn 2+ to said suspension to form said Zn MOF (Patent Document 2, Claim 1).

[0005] Patent Document 2 describes, as one embodiment of the production method, "Dissolve and / or suspend oxalic acid or its hydrate (1 molar equivalent) and 1,2,4-triazole (2 molar equivalents) in a lower alcohol or a miscible mixture of a lower alcohol and water, preferably ethanol or aqueous ethanol, to form a milky white precipitate of 1,2,4-triazolium oxalate. To this suspension, a basic zinc salt (2 molar equivalents of Zn) is added as a solid with vigorous stirring to form a viscous milky white suspension. Next, the suspension is stirred at room temperature until the reaction to form CALF-20 is complete as evaluated by PXRD. This reaction can take up to 16 - 22 hours at room temperature. The solid product CALF-20 is recovered by filtration, washed successively with water and ethanol (e.g., 5 - 10 mL each), and dried at room temperature." (Patent Document 2, Paragraph 0014). Here, CALF-20 is a Zn(II) material having the chemical formula Zn 2 Tz 2 Ox (where Tz = 1,2,4-triazolato, Ox = oxalate). Also, PXRD indicates powder X-ray diffraction. According to Patent Document 2, it is described that impurities can be avoided, the space-time yield can be increased, and at the same time, the safety risks associated with high pressure, high temperature and such conditions can be avoided (Patent Document 2, paragraph 0005).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The method for producing MOF disclosed in Patent Document 2 has a reaction temperature lower than 120 °C and is an economically superior method compared to the method disclosed in Patent Document 1. However, as described in paragraph 0017 of Patent Document 2, "the basic zinc salt can be basic zinc carbonate, zinc hydroxide, or zinc oxide, and these are poorly soluble to insoluble in alcohol, water, or a mixture thereof", so there is a limit to the uniform dispersion of zinc ions in MOF, and the reaction time is likely to be long. In view of such a situation, an object of the present invention is to provide a method for producing Zn-MOF in a short time at low cost.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that by using a zinc compound having a solubility in water of a certain level or more, a metal-organic framework containing zinc ions (hereinafter sometimes referred to as "Zn-MOF") can be synthesized in a short time at low cost, and thus the present invention has been completed. That is, the present invention relates to the following [1] to

[11] .[[]]END]]

[0009] [1] A method for producing a metal-organic framework containing a zinc ion coordinated with a triazolato and an oxalate which may have a substituent, comprising using a zinc compound having a solubility of 0.05 g or more in 100 cm of water at 25°C. 3 A method for producing a metal-organic framework. [2] The method for producing a metal-organic framework according to [1] above, wherein the zinc compound, a triazole compound which may have a substituent, and an oxalate compound are added to a solvent containing water and reacted. [3] The method for producing a metal-organic framework according to [2] above, wherein 0.8 to 3 moles of a triazole compound which may have a substituent and 0.4 to 0.6 moles of an oxalate compound are added per 1 mole of the zinc compound. [4] The method for producing a metal-organic framework according to [2] or [3] above, wherein the total concentration of the zinc compound, the triazole compound, and the oxalate compound is 0.1 to 10 mol / L in the solvent. [5] The method for producing a metal-organic framework according to any one of [2] to [4] above, wherein the solvent further contains alcohol. [6] The method for producing a metal-organic framework according to [5] above, wherein the ratio (volume ratio) of alcohol to water in the solvent is such that water is 0.3 or more and 20 or less with respect to 1 of alcohol. [7] The method for producing a metal-organic framework according to [5] or [6] above, wherein the alcohol is methanol and / or ethanol. [8] The method for producing a metal-organic framework according to any one of [2] to [7] above, wherein the reaction is stirred at 0 to 100°C for 5 minutes or more. [9] The method for producing a metal-organic framework according to any one of [1] to [8] above, wherein the zinc compound is zinc acetate.

[10] The method for producing a metal-organic framework according to any one of [2] to [9] above, wherein the triazole compound is 1,2,4-triazole.

[11] A method for producing a metal-organic framework according to any one of [2] to

[10] above, comprising a zinc compound solution preparation step of preparing a solution of the zinc compound, and an addition step of adding a triazole compound and an oxalate compound which may have a substituent to the zinc compound solution. [Advantages of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing a metal-organic framework capable of producing Zn-MOF in a short time at low cost. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0012] Hereinafter, embodiments of the present invention will be described in more detail. However, the description of the constituent elements described below is an example of an embodiment of the present invention. The present invention is not limited to these contents and can be implemented with various modifications within the scope of the gist.

[0013] [Method for Producing Metal-Organic Framework] The method for producing a metal-organic framework of the present invention (hereinafter, may be referred to as "the present production method") preferably comprises a mode in which a zinc compound, a triazole compound which may have a substituent, and an oxalate compound are added to a solvent containing water, and stirred and mixed to react. As the zinc compound, 100 cm of water at 25 ° C 3The method is characterized by using a zinc compound having a solubility of 0.05 g or more in water (hereinafter, sometimes referred to as a "water-soluble zinc compound"). By using such a water-soluble zinc compound, Zn-MOF can be produced inexpensively in a short time. Furthermore, by using a zinc compound with a certain level of solubility in water, it is considered that the distribution of zinc in the metal-organic framework becomes uniform, and a metal-organic framework with few structural defects and a high ratio of effective pores can be obtained. By using a metal-organic framework with a uniform distribution of zinc, for example, there are effects such as improving the gas permeability of a composition containing the metal-organic framework. The zinc compound can be dissolved in 100 cm of water at 25°C. 3 The solubility in the solution is preferably 0.05 g or more, more preferably 0.1 g or more, even more preferably 1 g or more, and particularly preferably 10 g or more, because it is believed that the Zn-MOF can be synthesized in a shorter time and that the distribution of zinc in the metal-organic framework is uniform. There is no particular upper limit, and the upper limit is usually 500 g or less.

[0014] <Zinc compounds> The zinc compound used in the present invention is a zinc compound having a concentration of 100 cm3 in water at 25°C. 3 Examples of the zinc nitrate include zinc acetate, zinc acetylacetonate, zinc sulfate, zinc chloride, zinc bromide, zinc iodide, zinc nitrate, zinc gluconate, zinc salicylate, and hydrates thereof. Among these, from the viewpoint that the counter anion of zinc promotes the deprotonation of triazole in the manufacturing process of MOF, zinc acetate, zinc acetylacetonate, zinc sulfate, zinc chloride, zinc nitrate, zinc gluconate, and zinc salicylate are preferred, zinc acetate and zinc acetylacetonate are more preferred, and zinc acetate is particularly preferred.

[0015] <Triazole compounds> The triazole compounds used in this manufacturing method include 1,2,3-triazole, 1,2,4-triazole which may have substituents, and triazolates which are their ions. The position of the substituent is not particularly limited. For example, a compound in which a hydrogen atom bonded to carbon is substituted may be used. Examples of the substituent include an amino group, a nitro group, a methyl group, and a mercapto group, and the number of substituents may be one or two. Among the triazole compounds, 1,2,3-triazole and 1,2,4-triazole are more preferred, and 1,2,4-triazole or its ions are particularly preferred in that there is less steric hindrance with adjacent ligands when forming a metal-organic framework. Note that the shape of the triazole compound which may have a substituent in this manufacturing method is not limited, and it may be liquid or solid at room temperature. Further, a triazole compound which may have a solid substituent can be used by dissolving or dispersing it in a solvent.

[0016] <Oxalate compound> The oxalate compound refers to oxalic acid and the dianion or monoanion of oxalic acid which is a diacid. Examples of the oxalate compound include oxalic acid, lithium oxalate, sodium oxalate, potassium oxalate, potassium hydrogen oxalate, ammonium oxalate, and their hydrates. From the viewpoint of low cost, lithium oxalate, sodium oxalate, potassium oxalate, and their hydrates are preferred, and sodium oxalate and its hydrates are particularly preferred. The shape of the oxalate compound in this manufacturing method is not limited, and it may be liquid or solid at room temperature. Further, the oxalate compound can be used by dissolving or dispersing it in a solvent.

[0017] <Solvent> In this manufacturing method, a water-soluble zinc compound, an optionally substituted triazole compound, and an oxalate compound are added to a solvent, followed by stirring and mixing for reaction. The solvent only needs to contain water, preferably contains alcohol, and more preferably contains an organic solvent such as a lower alcohol with about 1 to 6 carbon atoms that is highly compatible with water. As the lower alcohol, those with high compatibility with water are preferred. For example, methanol, ethanol, isopropanol, etc. are preferred. Among them, methanol and ethanol are particularly preferred in terms of having a small number of carbon atoms and high polarity. Note that the lower alcohol may be one type or a combination of two or more types. For example, methanol and ethanol may be mixed and used. The mixing ratio of alcohol and water in the mixed solvent is not particularly limited as long as they are compatible. For example, as the volume ratio of alcohol:water, it is preferably in the range of 0.3 or more and 20 or less of water with respect to 1 of alcohol, more preferably in the range of 0.4 or more and 19 or less of water with respect to 1 of alcohol, and even more preferably in the range of 0.6 or more and 4 or less of water with respect to 1 of alcohol. When the mixing ratio of alcohol and water is within this range, the polarity of the solvent becomes suitable for the formation of the target metal-organic framework, with fewer impurities and a high CO 2 adsorption capacity metal-organic framework is considered to be obtained.

[0018] <Molar ratio of raw materials> In this manufacturing method, it is preferable to add 0.8 to 3 moles of an optionally substituted triazole compound and 0.4 to 0.6 moles of an oxalate compound per 1 mole of the zinc compound. More preferably, 1.5 to 2.5 moles of an optionally substituted triazole compound and 0.45 to 0.55 moles of an oxalate compound are added per 1 mole of the zinc compound. Even more preferably, 1.8 to 2.2 moles of an optionally substituted triazole compound and 0.48 to 0.52 moles of an oxalate compound are added per 1 mole of the zinc compound. Within this range, Zn-MOF can be efficiently synthesized, the yield of Zn-MOF can be improved, and the CO 2 adsorption amount of the obtained metal-organic framework increases. In terms of stoichiometry, 1 mole of triazole and 0.5 mole of oxalate are added per 1 mole of zinc compound. However, from the perspective of further improving the yield, it is more preferable to add 1.5 - 2.5 moles of a triazole compound which may have a substituent and 0.45 - 0.55 moles of an oxalate compound per 1 mole of zinc compound. Even more preferably, 1.8 - 2.2 moles of a triazole compound which may have a substituent and 0.48 - 0.52 moles of an oxalate compound are added per 1 mole of zinc compound.

[0019] <Reaction conditions> As for the reaction pressure in this production method, it is usually from normal pressure to self - pressurization. In the case of self - pressurization, a reaction is carried out using an autoclave or the like, but from the perspective of simplicity, it is preferably at normal pressure. As for the reaction temperature in this production method, any condition can be used as long as the liquid is a solution under the reaction pressure. As the condition for the solvent to be liquid at normal pressure, it is usually 0°C or higher and 100°C or lower, preferably 5°C or higher and 80°C or lower, more preferably 10°C or higher and 50°C or lower, and even more preferably 10°C or higher and 35°C or lower. Under this condition, it can be produced at low cost and a high yield can be obtained. Since the reaction can proceed even at room temperature (for example, 25°C), from the perspective of energy efficiency, it is particularly preferable to carry out the reaction at room temperature. Also, as for the stirring time (reaction time), if it is 5 minutes or more, Zn - MOF can be synthesized. However, in order to further increase the yield and obtain sufficient performance of the produced Zn - MOF, the reaction time is more preferably 15 minutes or more, even more preferably 30 minutes or more, and it may be 60 minutes or more. Note that the stirring time means the time immediately after all the raw materials are added. Also, there is no particular limitation on the stirring speed, and it may be appropriately adjusted according to the viscosity.

[0020] There are also no particular restrictions on the order of raw material input. The zinc compound, the triazole compound which may have a substituent, and the oxalate compound may be added to the solvent simultaneously or sequentially. When adding them sequentially, there are also no particular restrictions on the order. For example, the order may be a zinc compound, a triazole compound which may have a substituent, and an oxalate compound; or a zinc compound, an oxalate compound, and a triazole compound; or a triazole compound which may have a substituent, an oxalate compound, and a zinc compound. However, when the zinc compound is added first, the distribution of zinc becomes uniform, and for example, effects such as improvement in the gas permeation characteristics of the composition containing the metal-organic framework can be obtained, so it is considered preferable in this regard. Also, the substances added second and later to the solvent may be added as they are, or may be dissolved or dispersed in another solvent and then added. The type of solvent at this time is the same as the above-mentioned solvent. The same applies to the mixing ratio of the solvents. Here, the mixing ratio of the solvents is the ratio in the total amount of the solvents at the time when all the compounds have been added. The interval in the case of sequential addition is not particularly limited but is usually within 1 hour, preferably within 30 minutes, more preferably within 10 minutes, and even more preferably within 5 minutes. The lower limit is not particularly limited, and usually, it is sufficient that the compound added in the previous step is in a state of being sufficiently dissolved or dispersed.

[0021] As one aspect of this production method, there is the following aspect. That is, it is a method for producing Zn-MOF, which has a zinc compound solution preparation step of preparing a solution of the zinc compound, and an addition step of adding a triazole compound which may have a substituent and an oxalate compound to the zinc compound solution. More specifically, in the step of preparing the zinc compound solution, the zinc compound is put into and mixed with the solvent to prepare a zinc compound solution, and a triazole compound and an oxalate compound which may have a substituent are added to this zinc compound solution. As for the addition order of the triazole compound and the oxalate compound which may have a substituent, both may be added simultaneously or sequentially. In that case, the order may be the triazole compound having a substituent, the oxalate compound, or the oxalate compound, the triazole compound having a substituent. When adding the triazole compound and the oxalate compound which may have a substituent to the zinc compound solution, they may be added as they are, or may be dissolved or dispersed in another solvent and then added. The type of solvent at this time is the same as the above-mentioned solvent, and the same applies to the ratio of the mixed solvent. Here, the mixing ratio of the solvents is the ratio in the total amount of the solvents at the time when all the compounds have been added.

[0022] When reacting in a solvent, the total concentration of all raw materials (zinc compound, oxalate compound, triazole compound which may have a substituent) is usually 0.1 mol / L or more, preferably 0.3 mol / L or more, more preferably 0.5 mol / L or more, still more preferably 0.7 mol / L or more, particularly preferably 1.0 mol / L or more, and usually 10 mol / L or less, preferably 5 mol / L or less, more preferably 3 mol / L or less. When it is above the above lower limit value, the reaction proceeds sufficiently and the yield of Zn-MOF can be increased. On the other hand, when it is below the above upper limit value, it is advantageous in that the yield can be increased because it is in a viscosity range where sufficient stirring can be performed. When reacting in a solvent, the concentration of the zinc compound is usually 0.01 mol / L or more, preferably 0.07 mol / L or more, more preferably 0.15 mol / L or more, still more preferably 0.3 mol / L or more, and usually 5 mol / L or less, preferably 2 mol / L or less, more preferably 1 mol / L or less. When the concentration of the zinc compound is within the above range, the reaction proceeds sufficiently and the yield of Zn-MOF can be increased. When reacting in a solvent, the concentration of the triazole compound which may have a substituent is usually 0.05 mol / L or more, preferably 0.15 mol / L or more, more preferably 0.3 mol / L or more, still more preferably 0.6 mol / L or more, and is usually 10 mol / L or less, preferably 5 mol / L or less, more preferably 2 mol / L or less. When the concentration of the triazole compound which may have a substituent is within the above range, the reaction proceeds sufficiently and the yield of Zn-MOF can be increased. When reacting in a solvent, the concentration of the oxalate compound is usually 0.01 mol / L or more, preferably 0.04 mol / L or more, more preferably 0.8 mol / L or more, still more preferably 0.15 mol / L or more, and is usually 2.5 mol / L or less, preferably 1.2 mol / L or less, more preferably 0.6 mol / L or less. When the concentration of the oxalate compound is within the above range, the reaction proceeds sufficiently and the yield of Zn-MOF can be increased.

[0023] <Metal-Organic Framework (MOF)> As described above, the MOF in the Zn-MOF produced by this production method is an abbreviation of Metal Organic Frameworks, and is a crystalline porous compound having a regular pore structure formed by metal ions and organic ligands. In the present invention, the metal ion is a zinc ion, and the metal-organic framework (MOF) according to the present invention contains zinc ions coordinated with triazolates and oxalates which may have substituents.

[0024] Examples of the triazolates coordinated to the zinc ions which may have substituents and which constitute the MOF according to the present invention include 1,2,3-triazolates represented by the formula (1) and 1,2,4-triazolates represented by the formula (2) in a state of being coordinated to the zinc ions. Among them, 1,2,4-triazolates are preferred.

[0025]

Chemical formula

[0026] In the formula, R 1 and R 2 are each independently an amino group, a nitro group, a methyl group, a mercapto group, or a hydrogen atom. It is preferable that at least one of R 1 and R 2 is a hydrogen atom. For example, R 1 and R 2 may be hydrogen atoms.

[0027] The MOF according to the present invention usually has pores. When the MOF according to the present invention has pores, the size of the pores is not particularly limited, but is usually in the range of 0.3 to 2 nm. When the pore size is in this range, excellent carbon dioxide adsorption ability can be exhibited. The pore size of the MOF according to the present invention is preferably 0.4 to 1.9 nm, more preferably 0.5 to 1.8 nm, still more preferably 0.6 to 1.7 nm, and particularly preferably 0.7 to 1 nm.

[0028] As described above, the MOF according to the present invention has high carbon dioxide adsorption ability. Specifically, the carbon dioxide adsorption amount of the MOF according to the present invention is the value of the carbon dioxide adsorption amount at an absolute pressure P = 102 kPa, which is measured by the constant-volume gas adsorption method using carbon dioxide after pretreatment by heating at 200 °C for 4 hours or more in a vacuum state to measure the adsorption isotherm at a temperature of 298 K. The carbon dioxide adsorption amount of the MOF of the present invention at an absolute pressure of 102 kPa is usually 1.0 mmol / g or more, preferably 2.0 mmol / g or more, more preferably 3.0 mmol / g or more, still more preferably 3.5 mmol / g or more. On the other hand, it is usually 100 mmol / g or less, preferably 50 mmol / g or less, more preferably 10 mmol / g or less. When the carbon dioxide adsorption amount is in the above range, a large amount of carbon dioxide can be efficiently adsorbed and desorbed.

[0029] The MOF according to the present invention is excellent in water resistance. The water resistance of the MOF can be determined from the changes in crystallinity and nitrogen adsorption amount before and after exposing the MOF to (i) water vapor, (ii) immersing it in water, (iii) immersing it in hot water, or (iv) heating it while immersed in water. Here, the nitrogen adsorption amount of the MOF is derived from the pore structure of the MOF, and the higher the proportion of pores maintained, the more the nitrogen adsorption amount is maintained after these treatments.

[0030] (iv) The ratio (after treatment / before treatment) of the nitrogen adsorption amount of the MOF of the present invention at a relative pressure P / P 0 = 0.1 before and after hydrothermal treatment is usually 60% or more, preferably 70% or more, more preferably 80% or more, still more preferably 85% or more, and usually 100% or less. When the ratio of the nitrogen adsorption amount before and after treatment is within the above range, practical performance can be easily maintained over a long period as an adsorbent or a composition containing the adsorbent.

[0031] The primary particle diameter of the MOF according to the present invention is usually 100 nm or more, preferably 200 nm or more, more preferably 500 nm or more, and on the other hand, usually 10 μm or less, preferably 5 μm or less, more preferably 2.5 μm or less. When the primary particle diameter is within the above range, the surface area of the MOF is appropriate, so the access from the MOF surface to the internal pores, which are the main adsorption sites, is good, the adsorption rate is increased, and the adsorption amount is also increased. Here, the "primary particle diameter" is obtained by photographing a sample in which the synthesized MOF is dispersed using a scanning electron microscope, measuring the particle diameters of 30 arbitrarily selected primary particles, and taking the arithmetic mean as the primary particle diameter. The average primary particle diameter of the MOF in the composition containing the obtained MOF and the resin is obtained by photographing a cross-section of the composition obtained by freeze fracture using a scanning electron microscope, measuring the particle diameters of 30 arbitrarily selected primary particles of the MOF visible in the cross-section, and taking the arithmetic mean as the primary particle diameter. Note that the particle diameter is the diameter (equivalent circle diameter) of a circle having an area equal to the projected area of the particle.

[0032] The particle size distribution in the present invention is a volume-based particle size distribution. The particle size distribution in the present invention can be determined by photographing a sample in which the synthesized MOF is dispersed using a scanning electron microscope and measuring the particle diameters of arbitrarily selected 30 primary particles. The particle size distribution of the MOF in the composition containing the obtained MOF and the resin can be determined by photographing a cross-section of the composition obtained by freeze fracture using a scanning electron microscope and measuring the particle diameters of arbitrarily selected 30 primary particles of the MOF visible in the cross-section. It is preferable that there are two or more peaks in the volume-based particle size distribution in the present invention, and particularly preferably, the particle size distribution is bimodal, divided into two regions. In the bimodal distribution, the mode value of the particle diameter in the small particle size region is usually 100 nm or more, preferably 200 nm or more, more preferably 500 nm or more, usually 5 μm or less, preferably 4 μm or less, more preferably 3 μm or less, still more preferably 2 μm or less, and the mode value of the particle diameter in the large particle size region is usually 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, usually 20 μm or less, preferably 10 μm or less, more preferably 6 μm or less. When the mode values of the particle diameters in the small particle size region and the large particle size region are within this range in the bimodal peak, small particles can enter between the large particles in the MOF composition, thereby improving the filling amount of the MOF in the composition. Also, in a film composed of MOF and resin, small particles can enter between the large particles, thereby improving the MOF filling amount in the film without defects. In the bimodal distribution, the ratio of the mode value of the particle diameter in the large particle size region to the mode value of the particle diameter in the small particle size region is usually 1.5 or more, preferably 2.0 or more, more preferably 3.0 or more, and usually 50 or less, preferably 20 or less, still more preferably 10 or less, particularly preferably 7 or less.

[0033] The shape of the secondary particles of the MOF of the present invention is not particularly limited, but the circularity coefficient is preferably 0.80 or more, usually 1.0 or less as the average circularity coefficient. When the average circularity coefficient is within this range, since the fluidity of the particles is high, it becomes possible to improve the filling rate of the MOF in a molded body such as a pellet used as an adsorbent or the filling rate of the MOF in the resin composition of the MOF of the present invention, and a molded adsorbent with a large adsorption amount per unit volume can be obtained. In addition, as a composition, the performance of gas permeation and separation tends to be high. The circularity coefficient referred to here is 4πS / L when the area of the two-dimensional projection image of the particles of the MOF used is S and the perimeter of the particles is L. 2 It is represented by, and becomes 1.0 when the particles are perfect spheres, and the closer to a perfect sphere, the larger the value. Therefore, a shape with an average circularity coefficient of 0.80 or more is, for example, a spherical shape or a rugby ball shape. The method for calculating the average circularity coefficient referred to here is specifically as follows.

[0034] [Method for calculating average circularity coefficient] The powder of the MOF particles of the present invention is well dispersed to prepare a sample, which is photographed using a scanning electron microscope. The circularity coefficient is calculated for 30 arbitrarily selected particles, and the arithmetic mean is taken as the average circularity coefficient. In the case of secondary particles formed by aggregation of small crystal particles, the circularity coefficient is calculated for the secondary particles, and the average value is taken. The average circularity coefficient of the MOF in the composition containing the obtained MOF and resin is obtained by photographing the cross-section of the composition obtained by freeze fracture using a scanning electron microscope, and calculating the circularity coefficient of 30 arbitrarily selected particles for the MOF visible in the cross-section, and taking the arithmetic mean as the average circularity coefficient.

[0035] <Composition> According to the present invention, there is provided a composition containing a MOF containing zinc ions coordinated with optionally substituted triazolates and oxalates, and a resin. The composition of the present invention contains at least a metal-organic framework (MOF) containing zinc ions coordinated with a triazolato and an oxalate which may have substituents, and a resin. The form of the composition may be at least a fluid or a solid mixture containing the MOF and the resin. In the case of a solid, it may be formed into a film.

[0036] (resin) The resin contained in the composition of the present invention is not particularly limited, but is preferably at least one selected from the group consisting of polyimides, polyamides, polysulfones, polyvinylpyrrolidone, polybenzimidazoles, polybenzoxazoles, polyoxyethylene, polyphenylene ethers, polyether ketones, polyketones, tetrafluoroethylene amorphous polymers, macroporous polymers (PIM), polyether block amides, silicone rubbers composed of polyorganosiloxanes such as polydimethylsiloxane (hereinafter sometimes referred to as PDMS), styrene-butadiene rubbers, butadiene rubbers, isoprene rubbers, ethylene-propylene rubbers, natural rubbers, acrylic rubbers, ethylene-vinyl oxide rubbers, and polyolefins such as poly(4-methyl-1-pentene).

[0037] The resin contained in the composition of the present invention may be coordinated to the metal ions of the MOF. When the resin is coordinated, the resin preferably has at least one functional group selected from the group consisting of an amino group, an imidazolium group, a carboxy group (-COOH), a phenolic hydroxy group (-PhOH), a thiol group (-SH), a sulfo group (-SO 3 H), a phosphonic acid group (-PO 3 H 2 ), and a phosphate group (-OPO 3 H 2 ). Among these, a carboxy group and an imidazole group are preferred because they are easily coordinated to the metal ions of the MOF.

[0038] The resin contained in the composition of the present invention may be chemically bonded to the MOF. When the resin is chemically bonded, the resin preferably has at least one functional group selected from the group consisting of a hydroxyl group, an epoxy group, an amino group, an isocyanate group, a cyano group, an acrylic group, a methacrylic group, a vinyl group, a thiol group, a carbonyl group, a carboxylic anhydride, and derivatives thereof.

[0039] From the viewpoint of hardly causing infiltration into the base material and hardly generating defects when the composition of the present invention is applied to the base material, the weight average molecular weight (Mw) of the resin contained in the composition of the present invention is preferably high. On the other hand, from the viewpoint of being easily diluted by a solvent and having excellent film-forming properties, it is preferably low. Therefore, the weight average molecular weight is preferably 1,000 to 500,000, more preferably 1,500 to 100,000, and still more preferably 3,000 to 50,000.

[0040] From the viewpoint of efficiently performing the separation and adsorption of carbon dioxide, it is preferable that the content of MOF in the composition is high. Therefore, the glass transition temperature (Tg) of the resin contained in the composition of the present invention in a cured or solidified state is preferably low from the viewpoint of easily containing MOF at a high concentration and having excellent film-forming properties and flexibility.

[0041] That is, when the glass transition temperature of the resin is low, when a film made of the composition of the present invention is used for gas separation, even if the content of MOF is increased, since the resin as the matrix has flexibility, a film showing high permeation and separation performance can be obtained without generating a gap between the MOF and the resin. Further, when the glass transition temperature of the resin is low, even if distortion occurs at the interface between the matrix resin and the MOF due to high-pressure conditions or long-term use, it can be absorbed by the flexibility of the resin, and gaps are less likely to occur. Furthermore, since the resin has flexibility, even when the film is processed into a shape such as a spiral and modularized, no gap is generated between the matrix resin and the MOF, and good film performance can be obtained. Therefore, the glass transition temperature of the resin is preferably 15° C. or lower, more preferably 0° C. or lower, even more preferably −20° C. or lower, particularly preferably −50° C. or lower, even more preferably −70° C. or lower, and most preferably −100° C. or lower. The lower limit of the glass transition temperature of the resin is not particularly limited, but is preferably −250° C., more preferably −200° C. The method for measuring the glass transition temperature is in accordance with the method described in the Examples.

[0042] The resin contained in the composition of the present invention has a CO 2 The gas permeability coefficient of the resin is preferably high because the gas permeability coefficient is likely to be high when the composition of the present invention is used as a membrane. Specifically, the gas permeability coefficient of the resin is preferably 200 Barrer or more, more preferably 500 Barrer or more, even more preferably 1000 Barrer or more, particularly preferably 1500 Barrer or more, and most preferably 2000 Barrer or more. Here, CO at 35°C 2 The permeability coefficient of CO for a membrane made only of resin (hereinafter sometimes referred to as a "resin membrane") is 2 The permeability coefficient of the resin is measured at a differential pressure of 0.1 MPa. The permeability coefficient, separation coefficient, and permeability of the resin are measured at 35° C. and a differential pressure of 0.1 MPa by preparing a resin membrane and using the same method as the measuring method of the permeability coefficient, separation coefficient, and permeability of the membrane of the present invention described later.

[0043] Favorable glass transition temperature and CO 2Examples of the resin having the gas permeability coefficient include polyether block amide, silicone rubber made of polyorganosiloxane such as PDMS, styrene-butadiene rubber, butadiene rubber, isoprene rubber, ethylene-propylene rubber, natural rubber, acrylic rubber, rubbers such as ethylene-vinyl oxide rubber, and polyolefins such as poly(4-methyl-1-pentyne). Polyether block amide, silicone rubber made of polyorganosiloxane such as PDMS, styrene-butadiene rubber, butadiene rubber, isoprene rubber, ethylene-propylene rubber, natural rubber, acrylic rubber, rubbers such as ethylene-vinyl oxide rubber are more preferable, and silicone rubber made of polyorganosiloxane such as PDMS is particularly preferable. By producing a membrane using a composition containing these resins, a gas separation membrane excellent in gas permeation performance and separation performance can be obtained.

[0044] The above-mentioned preferable silicone rubber is not particularly limited, but polyorganosiloxane having a siloxane skeleton represented by the following formula (3) or a cured product obtained by crosslinking a commercially available silicone rubber precursor is preferable. Examples of the commercially available silicone rubber precursor include SILPOT TM 184 Silicone Elastomer Base (manufactured by Dow Corning Toray Co., Ltd.).

[0045] [Chemical formula]

[0046] In formula (3), n is an integer of 2 or more, R 11 and R 12is, independently of each other, a hydrogen atom; a hydroxy group; an alkyl group such as a methyl group or an ethyl group; a cycloalkyl group such as a cyclohexyl group; a polyether group; an alkenyl group such as a vinyl group or an allyl group; an aryl group such as a phenyl group or a fluorenyl group; a heteroalkyl group such as a fluoroalkyl group; or a saturated or unsaturated alicyclic group containing a hetero element such as an oxiranyl group or an oxetanyl group, and may have a substituent that undergoes a condensation reaction such as an alkoxy group, a ketoxime group, an acetoxy group, or an aminoxy group, or a substituent such as an amino group, a carboxy group, a carbinol group, or an epoxy group. In addition, as the substitution form of the polyorganosiloxane of formula (3), R on the side chain 11 , R 12 may be substituted, both terminals may be substituted, or both terminals and the side chain may be substituted. R 11 and R 12 may be the same as or different from each other, and only a part of R 11 , R 12 in the polyorganosiloxane may be substituted.

[0047] In terms of polymerizing or condensing the polyorganosiloxane of formula (3) by a crosslinking reaction to form a silicone rubber, the polyorganosiloxane of formula (3) preferably has a crosslinkable group such as an alkenyl group including a vinyl group, a silicon-hydrogen bond, an oxetanyl group, an alkoxy group, a ketoxime group, an acetoxy group, or an aminoxy group, and particularly preferably has an alkenyl group in terms of being able to utilize an addition reaction.

[0048] Examples of commercially available polyorganosiloxanes having a hydroxy group at the terminal of formula (3) include poly(dimethylsiloxane), hydroxy-terminated (viscosity 2550 - 3570 cSt), poly(dimethylsiloxane), hydroxy-terminated (viscosity 18,000 - 22,000), and poly(dimethylsiloxane), hydroxy-terminated (viscosity ~50,000 cSt) manufactured by Aldrich, and poly(dimethylsiloxane), hydroxy-terminated (viscosity 18,000 - 22,000) is particularly preferred.

[0049] In terms of polymerizing or condensing the polyorganosiloxane of formula (3) by a crosslinking reaction to obtain a silicone rubber, the polyorganosiloxane of formula (3) preferably has a crosslinkable group such as an alkenyl group including a vinyl group, a silicon-hydrogen bond, a hydroxy group, an oxetanyl group, an alkoxy group, a ketoxime group, an acetoxy group, an aminoxy group, etc., and it is particularly preferable to have a silicon-hydrogen bond, an alkenyl group that can utilize an addition reaction, or a hydroxy group that can utilize a condensation reaction.

[0050] The mechanism of the crosslinking reaction when crosslinking and curing the above polyorganosiloxane to obtain a silicone rubber is not particularly limited, and a curing reaction by a conventionally known organic peroxide, a condensation reaction, an addition reaction, a curing reaction by ultraviolet rays, radiation, or electron beam irradiation can be utilized. From the viewpoint of productivity, a type that cures by an addition reaction, a condensation reaction, ultraviolet rays, radiation, or electron beam irradiation is preferable in terms of being easy to mix with MOF and being able to stably store after mixing with MOF in the atmosphere, and it is particularly preferable to utilize an addition reaction or a condensation reaction in that it does not require atmosphere control other than temperature and humidity during curing and is simple.

[0051] When using polyorganosiloxane, the weight average molecular weight (Mw) is usually 5,000 or more, preferably 10,000 or more, more preferably 20,000 or more, still more preferably 25,000 or more, and on the other hand, usually 100,000 or less. When the weight average molecular weight of the polyorganosiloxane contained in the composition of the present invention is within the above range, mixing with MOF becomes easy, the content of MOF in the composition of the present invention can be increased, and the film-forming property is also excellent. Examples of the polyorganosiloxane that can be preferably used in the present invention include SILPOT manufactured by Dow Corning Toray Co., Ltd. TM 184, ELASTOSIL RT601 manufactured by Asahi Kasei Wacker Silicone Co., Ltd., TSE382-C manufactured by Momentive Performance Materials Japan Co., Ltd., etc.

[0052] (Composition) The composition of the present invention preferably contains 5 to 95% by mass of MOF. The content of MOF in the composition of the present invention is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, particularly preferably 30% by mass or more, even more preferably 40% by mass or more, and most preferably 50% by mass or more. On the other hand, it is usually less than 100% by mass, preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, particularly preferably 80% by mass or less. When the content of MOF in the composition of the present invention is within the above range, the composition of the present invention is excellent in flexibility and processability and is suitable for various applications. In the present invention, 100 cm of water at 25 °C 3 It is preferable to produce the metal-organic framework as described above by reacting a zinc compound having a solubility of 0.05 g or more in 100 cm of water at 25 °C in a solvent. Using this method, it is considered that the distribution of zinc in Zn-MOF can be made uniform, and the effect of Zn-MOF in the composition is efficiently exhibited. For example, the permeation amount of a predetermined gas in the composition is likely to be improved. Furthermore, when this method is used, a bimodal particle size distribution may be obtained, which may be advantageous for increasing the proportion of MOF in the composition.

[0053] The composition of the present invention has a high viscosity by containing MOF. Therefore, in order to facilitate film formation, the viscosity may be adjusted by containing an organically modified silicone resin or an organically modified silicone oil. As the organically modified silicone resin and the organically modified silicone oil, those described in JP-A-2017-66364 can be used.

[0054] Examples of the organic group of the organically modified silicone resin and the organically modified silicone oil include an epoxy group, an alcohol group, a carboxy group, an acrylic group, a methacrylic group, a thiol group, an amino group, an ether group, an aralkyl group, and an alkyl group. Among them, an epoxy group, an alcohol group, and a carboxy group are preferable, and an epoxy group is particularly preferable.

[0055] Organic-modified silicone resins and organic-modified silicone oils have organic groups with appropriate polarity, so they are likely to adsorb to MOF. Therefore, by containing these components, the increase in viscosity due to the inclusion of MOF is alleviated. Specifically, the silicone part, which is the -Si-O-Si- bond part of the organic group-modified silicone resin and organic-modified silicone oil, contacts the low-polarity site of MOF, or the organic group part contacts the polar site of MOF, and by functioning as a surfactant that eliminates the phase separation structure in the composition, the dispersibility of MOF in the composition is improved, and MOF can be contained at a high concentration without impairing the film-forming property.

[0056] The content of the organic-modified silicone resin and organic-modified silicone oil in the composition of the present invention (the total amount when both components are included) is usually 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more. On the other hand, it is usually 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less. When the content of the organic group-modified silicone resin or organic-modified silicone oil is within the above range, the viscosity of the composition of the present invention can be lowered, the dispersibility of MOF can be improved, and a film excellent in long-term stability can be obtained.

[0057] <Film> In the present invention, a film comprising the composition of the present invention described above is provided. The film comprising the composition of the present invention may also be referred to as an organic-inorganic hybrid film. The film may contain, in addition to the composition of the present invention, a base material, an underlayer, and a protective layer, which will be described later. The film comprising the composition of the present invention can be suitably used as a separation membrane, particularly for gas separation, especially carbon dioxide gas separation.

[0058] The content of MOF in the film of the present invention is usually 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, particularly preferably 30% by mass or more, even more preferably 40% by mass or more, and most preferably 45% by mass or more. On the other hand, it is usually 95% by mass or less, preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less. When the content of MOF is within the above range, a film excellent in flexibility and processability is likely to be obtained.

[0059] (Substrate) The film of the present invention may be used alone, or the film of the present invention may be laminated on a substrate (hereinafter, this laminate may also be referred to as the "film of the present invention" or simply "film" in some cases). By laminating the film composed of the composition of the present invention on the substrate, compared with the case of using only the film composed of the composition of the present invention, the durability and strength of the film are increased, and it is preferable in that the film composed of the composition of the present invention can be made thinner.

[0060] From the viewpoint of excellent permeation performance of the film of the present invention, a porous substrate is preferable as the substrate. The shape of the porous substrate is not particularly limited, and examples thereof include a porous membrane, a porous hollow fiber membrane, and a non-woven fabric. A porous hollow fiber membrane is preferable because the membrane area per unit volume can be increased. The pore diameter of the porous substrate is usually 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less, still more preferably 5 μm or less, particularly preferably 1 μm or less, and most preferably 0.5 μm or less. On the other hand, it is usually 0.01 μm or more, preferably 0.1 μm or more, and more preferably 0.2 μm or more. When the pore diameter of the substrate is within the above range, gas can easily permeate through the film, and the strength is excellent. The structure of the porous substrate of the substrate may be uniform or an asymmetric structure having a rough layer under the surface dense layer. However, an asymmetric structure is preferable because it is easy to reduce the resistance during gas permeation.

[0061] The thickness of the porous substrate is preferably large in terms of film strength, but on the other hand, it is preferably small in terms of gas permeability. Therefore, the thickness of the porous substrate is usually 10 μm or more, preferably 30 μm or more, more preferably 50 μm or more, still more preferably 70 μm or more, particularly preferably 100 μm or more, and on the other hand, usually 2 mm or less, preferably 1 mm or less, more preferably 500 μm or less, still more preferably 200 μm or less, particularly preferably 150 μm or less.

[0062] The material of the porous substrate is not particularly limited, but it is usually a polymer, preferably at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polysulfone (PSU), cellulose acetate (CA), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyimide (PI), polyacrylonitrile (PAN), and polyamide, more preferably at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethersulfone (PES), cellulose acetate (CA), and polyacrylonitrile (PAN), and particularly preferably polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). When the porous substrate is made of these materials, it is excellent in flexibility and strength, and there are few restrictions on the lamination method and conditions when laminating the film made of the composition of the present invention. Therefore, a film excellent in strength, flexibility, and processability can be obtained.

[0063] (Base layer) The substrate may have a multilayer structure. When the substrate has a multilayer structure, a base layer (= Gutter layer) may be further provided between the film made of the composition of the present invention and the substrate of the above-described preferred material. The material of the underlying layer is not particularly limited, and examples thereof include silicone resin, polyethersulfone (PES), polysulfone (PSU), polyethylene oxide (PEO), poly[1-(trimethylsilyl)-1-propyne] (PTMSP), and the like. Among these, silicone resin, polyethylene oxide (PEO), and particularly preferably silicone resin are used because they have high solvent resistance and few restrictions on the film-forming method when forming a film on the underlying layer. The thickness of the underlying layer is preferably thin in terms of reducing the permeation resistance as a separation membrane. Specifically, it is usually 1 nm or more, preferably 10 nm or more, and on the other hand, it is usually 3 μm or less, preferably 1.5 μm or less, more preferably 1 μm or less, and even more preferably 500 nm or less.

[0064] (Protective layer) The film of the present invention may have a protective layer. The material of the protective layer is not particularly limited, and examples thereof include silicone resin, poly[1-(trimethylsilyl)-1-propyne] (PTMSP), polyethersulfone (PES), polysulfone (PSU), polyethylene oxide (PEO), and the like. Among these, silicone resin, poly[1-(trimethylsilyl)-1-propyne] (PTMSP), and polyethylene oxide (PEO) are preferred, and silicone resin is particularly preferred because it has high gas permeability and little influence on the film made of the composition of the present invention. When providing a protective layer, it is preferably thin in terms of the gas permeability of the film, but on the other hand, it is preferably thick in terms of film strength and scratch resistance of the film. Therefore, the thickness when providing a protective layer is usually 1 nm or more, preferably 10 nm or more, more preferably 100 nm or more, and on the other hand, it is usually 100 μm or less, preferably 10 μm or less, more preferably 1 μm or less.

[0065] (Thickness of the film) The thickness of the film of the present invention is preferably thin in terms of excellent gas permeability and flexibility, and on the other hand, it is preferably thick in terms of excellent water resistance, hydrothermal stability, flexibility, and processability, with few cracks and pinholes and being easy to modularize. Therefore, when only using the film made of the composition of the present invention, it is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more. On the other hand, it is usually 1,000 μm or less, preferably 500 μm or less, more preferably 300 μm or less, still more preferably 250 μm or less, and particularly preferably 200 μm or less.

[0066] In addition, when there is a layer other than the film made of the composition of the present invention, the thickness of the film is usually 0.05 μm or more, preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 2 μm or more. On the other hand, it is usually 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably 5 μm or less. When the film made of the composition of the present invention is formed on a porous substrate or a porous protective film, the combined thickness of these substrates and protective layers is usually 0.05 μm or more, preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 2 μm or more. On the other hand, it is usually 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably 5 μm or less.

[0067] (Reverse bending test) The film of the present invention is excellent in flexibility. Specifically, the gas permeability coefficient, gas permeability, and separation coefficient of the film of the present invention after the reverse bending test (a test of bending 180° once along a curved surface with a bending radius (curvature radius) of 5 mm and then stretching) are preferably within 10% compared to before the bending test. Here, the bending radius (curvature radius) when performing the above reverse bending test is preferably 4 mm or less, more preferably 3 mm or less, still more preferably 2 mm or less. On the other hand, it is usually 0.1 mm or more, preferably 0.5 mm or more, more preferably 1 mm or more. Due to the excellent flexibility of the film of the present invention, the film of the present invention can be bent and used, has excellent processability, and can be easily processed into a spiral module or a pleated module without causing cracks or pinholes. Also, when forming the film into a hollow fiber shape, it becomes easy to form the film without causing cracks or pinholes in the film.

[0068] (Method for manufacturing a film) The film of the present invention can be manufactured by a known method for manufacturing a resin film. For example, it may be mixed with a resin obtained by dissolving MOF in a solvent or may be mixed with a resin to form a film. In the case of a resin that requires a curing step, it may be cured after forming a film by mixing with the resin before curing. Specifically, after drying MOF, it is mixed with a resin dissolved in a solvent or a solvent-free resin raw material, etc., and after dispersion, when using a resin that requires a curing agent, a curing agent is further added and mixed to disperse MOF.

[0069] As a method for dispersing MOF in a resin, in addition to normal stirring and kneading, methods such as crushing and dispersing by ultrasonic waves and using a rotation-revolution mixer can be mentioned. After putting a slurry obtained by mixing MOF, a resin or a resin raw material, and further optional components such as a curing agent and a solvent into a petri dish such as Teflon (registered trademark) or applying it on a release film, it is put into a dryer to remove the solvent and then cured at a predetermined temperature and time, or the resin is cured while volatilizing the solvent under a nitrogen stream using an inert oven, whereby the film of the present invention can be obtained. Here, the temperature and vacuum degree of the dryer are appropriately set according to the solvent used. The curing temperature and curing time may also be carried out under conditions suitable for the resin used.

[0070] When using a porous flat film as the substrate, the film of the present invention can be produced by forming a film of a certain thickness from the composition of the present invention using a blade on the substrate. Here, after previously preparing the composition of the present invention on the porous substrate, a protective layer may be formed thereon. Alternatively, a film may be formed on a substrate having an underlayer. The method for forming the protective layer and the underlayer may be carried out in accordance with the method for producing the film of the present invention. Alternatively, the above-described mixed slurry can be supported on the substrate by methods such as impregnation, suction, and pressurization to form a film. Thereafter, the solvent is removed using a dryer and then cured, or the resin is cured while volatilizing the solvent under a nitrogen stream using an inert oven, whereby the film of the present invention can be obtained.

[0071] When using a porous hollow fiber as the substrate, the composition of the present invention may be supported on the substrate by methods such as impregnation, suction, and pressurization to form a film.

[0072] When using a silicone rubber obtained by curing a polyorganosiloxane as the resin, the MOF is usually mixed with the polyorganosiloxane before curing. The means for curing the curable polyorganosiloxane is not particularly limited, and a conventionally known method can be adopted. From the viewpoint of productivity, it is preferable to cure by a curing method of a type that can stably carry out the mixing of the MOF and the storage after the mixing of the MOF in the atmosphere. In that regard, a type that cures by an addition reaction, ultraviolet rays, radiation, or electron beam irradiation is preferable, and it is particularly preferable to utilize an addition reaction in that the atmosphere control during curing is not required and it is simple.

[0073] Before mixing the resin and the MOF, it is preferable to dry the MOF. When heat-drying the MOF, the temperature is usually 100 °C or higher, preferably 120 °C or higher, and on the other hand, it is usually 200 °C or lower, preferably 170 °C or lower. The drying time is usually 3 hours or longer, preferably 5 hours or longer, more preferably 8 hours or longer, still more preferably 12 hours or longer, and on the other hand, it is usually 48 hours or shorter, preferably 30 hours or shorter, more preferably 20 hours or shorter. When the drying temperature and time are within these ranges, it is easy to sufficiently remove the moisture in the MOF in a short time.

[0074] The solvent used for film formation is not particularly limited as long as it is a solvent in which the resin or the resin raw material is soluble. For example, toluene, hexane, ethyl acetate, methyl ethyl ketone, N-methylpyrrolidone, etc. can be used. As the solvent, a solvent with good dispersibility of the MOF is preferable. Since many of the resin or the resin raw material are hydrophobic while the surface of the MOF is hydrophilic, a solvent having a medium polarity such as ethyl acetate or methyl ethyl ketone is preferable.

[0075] The amount of the solvent varies depending on the amount of the MOF and the type of the resin, but it is preferable to adjust the amount of the solvent according to the film formation method so that the viscosity is suitable for film formation.

[0076] In film formation, it is preferably carried out to cure the resin while applying pressure. By curing the resin while applying pressure, it is easy to produce a film without voids even when the amount of the MOF is large.

[0077] The pressurization method is not particularly limited, but it is preferable to heat and cure while applying pressure to the film using a hot press or a vacuum hot press. The magnitude of the pressure is usually 1 MPa or more, preferably 2 MPa or more, more preferably 3 MPa or more, still more preferably 4 MPa or more, and particularly preferably 5 MPa or more. On the other hand, it is usually 30 MPa or less, preferably 20 MPa or less, more preferably 10 MPa or less, and still more preferably 8 MPa or less. When the pressure is within the above range, a membrane with a large amount of MOF can be obtained without destroying the pores of the MOF in the membrane and without voids between MOFs or between MOF and the resin. The heating temperature and heating time may be appropriately determined according to the curing conditions of the resin used. However, the heating time while applying pressure is usually 1 minute or more, preferably 5 minutes or more, more preferably 10 minutes or more. On the other hand, it is usually 2 hours or less, preferably 1 hour or less. By heating within this range, it is easy to efficiently produce a membrane without voids.

[0078] <Gas separation and concentration method> The membrane of the present invention can separate and concentrate a gas mixture and can be used as a gas separation membrane. According to the separation membrane of the present invention, a gas with high permeability can be separated from a mixed gas. The mixed gas separated by the separation membrane of the present invention includes at least one component selected from carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, normal butane, isobutane, 1-butene, 2-butene, isobutene, sulfur hexafluoride, helium, carbon monoxide, nitric oxide, and water vapor, etc. Among these, it is suitable for separating at least one gas selected from the group consisting of carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, butane, butene, sulfur fluoride, helium, carbon monoxide, nitric oxide, and water vapor from the mixed gas. Among the above-mentioned mixed gas components, the gas component with high permeance (hereinafter, may also be referred to as "gas permeability") is separated and concentrated by passing through the membrane of the present invention, and the gas component with low gas permeability is concentrated on the supply gas side.

[0079] As the mixed gas, a gas containing at least two kinds of the above-mentioned components is more preferable. In this case, as the two kinds of components, a combination of a component with a high gas permeability and a component with a low gas permeability is preferable.

[0080] As for the gas separation use, it is preferably used for separation and concentration of CO 2 , separation and concentration of H 2 , separation and concentration of oxygen, separation and concentration of nitrogen, etc. Among them, it is particularly preferably used for separation and concentration of CO 2 and separation and concentration of H 2 .

[0081] As for the separation and concentration of CO 2 , removal of carbon dioxide from natural gas (CO 2 , CH 4 mixture), recovery of CO 2 from landfill gas (CO 4 , CH 2 mixture), recovery of CO 2 from synthetic fermentation gas (CO 4 , CH 2 mixture), recovery of CO 2 from combustion exhaust gas such as that from thermal power plants (CO 2 , N 2 mixture), etc. can be mentioned.

[0082] As for the separation and concentration of hydrogen, hydrogen recovery in the petroleum refining industry, hydrogen recovery and purification in various reaction processes in the chemical industry (H 2 , CO, CO 2 , hydrocarbon mixture), production of high-purity hydrogen for fuel cells, etc. can be mentioned. The production of hydrogen for fuel cells is obtained by the steam reforming reaction of methane, and separation of hydrogen from a mixed gas of hydrogen, carbon monoxide, methane, and water is required.

[0083] In addition, as for the separation and concentration of oxygen, production of oxygen-enriched gas from air (for medical use, oxygen-enriched air for combustion, etc.) can be mentioned, and it is also preferably used for production of nitrogen-enriched gas from air by nitrogen separation and concentration (for explosion prevention, oxidation prevention, etc.). Known gas separation methods can be used. For example, a partial pressure difference can be created as a pressure difference between the gas supply side and the gas permeation side of the membrane, and the gas that easily permeates from the mixed gas on the supply side can be allowed to permeate to the permeation side. At this time, the mixed gas on the gas supply side may be pressurized, or the permeation side may be depressurized using a vacuum pump or the like, or both may be used.

[0084] In the gas separation method applying a pressure difference between the gas supply side and the permeation side, it is preferably carried out at an appropriate and optimal pressure difference. Usually, it is 0.01 MPa or more, preferably 0.05 MPa or more, more preferably 0.08 MPa or more, still more preferably 0.1 MPa or more. On the other hand, usually it is 20 MPa or less, preferably 10 MPa or less, more preferably 5 MPa or less, still more preferably 1 MPa or less, particularly preferably 0.5 MPa or less, and most preferably 0.2 MPa or less.

[0085] The pressure on the gas supply side in the gas separation method is not particularly limited, but it is preferably used at an appropriate and optimal supply pressure. Usually, it is 0.05 MPaG or more, preferably 0.1 MPaG or more, usually 20 MPaG or less, preferably 10 MPaG or less, more preferably 5 MPaG or less, still more preferably 0.9 MPaG or less, particularly preferably 0.5 MPaG or less, and most preferably 0.2 MPaG or less. It is desirable to create a large differential pressure, but at high pressures, the cost for equipment that can withstand high pressures or to meet relevant laws and regulations becomes high.

[0086] In the gas separation and concentration method using the separation membrane of the present invention, a sweep gas may be used. The method using a sweep gas is a method of flowing some gas on the permeation side and recovering the gas that has permeated through the membrane. The pressure of the sweep gas is usually atmospheric pressure, but there is no particular limitation. Usually, it is 10 MPaG or less, preferably 5 MPaG or less, more preferably 1 MPaG or less, still more preferably 0.5 MPaG or less, particularly preferably 0.1 MPaG or less, and most preferably 0.05 MPaG or less. The lower limit is usually 0.0 MPaG.

[0087] <Adsorbent> According to the present invention, a carbon dioxide adsorbent containing the MOF of the present invention (hereinafter, sometimes referred to as "the CO 2 adsorbent of the present invention" or simply "CO 2 adsorbent") can be provided. That is, the MOF of the present invention can be suitably used as a CO 2 adsorbent. Since the CO 2 adsorbent of the present invention contains the MOF of the present invention, it can sufficiently adsorb carbon dioxide and has high selectivity of carbon dioxide adsorption with respect to nitrogen adsorption. Therefore, for example, it can be preferably used for the purpose of selectively removing carbon dioxide in exhaust gas from power plants, factories, automobiles, etc.

[0088] The CO 2 adsorbent of the present invention may be subjected to an activation treatment before use. As a method for activating the adsorbent, a method known in the art may be adopted. In a specific embodiment, the MOF contained in the adsorbent is activated by heating under reduced pressure. By activation, the adsorbed substances can be removed. More specifically, under reduced pressure, for example, 10 -3 mbar or less, preferably 10 -6 mbar, and by heating to a temperature of about 100 to about 150 °C, the MOF of the present invention contained in the adsorbent can be activated. In another embodiment, in a two-step heating process, a first step of heating to 60 °C for 2 hours under reduced pressure (preferably 10 -6 mbar) and a subsequent second step of heating to 100 °C for 12 hours can activate the MOF contained in the adsorbent. The activation may be performed by heating at a controlled rate (for example, 1 °C / min). For example, the MOF can be activated by heating to 60 °C at 1 °C / min for 2 hours and then heating to 100 °C at a heating rate of 1 °C / min for 12 hours. In another embodiment, the MOF contained in the adsorbent may be treated or washed with an organic solvent such as acetone before heating under reduced pressure.

[0089] The CO 2The adsorbent is not particularly limited in its configuration as long as it contains the MOF of the present invention. There are no particular restrictions on the usage form of the adsorbent of the present invention. For example, the adsorbent in powder form can be used as it is, or it can be supported on various substrates (such as aluminum honeycomb, etc.) and used, or it can be formed into various shapes and used as needed.

[0090] The adsorbent of the present invention may contain a binder in addition to the MOF. As the binder, either an inorganic binder or an organic binder can be used. Examples of the inorganic binder include silica binder and the like. Examples of the organic binder that can be used include polysulfone, polylactic acid, polyethylene glycol, and polyvinylpyrrolidone.

[0091] The adsorbent of the present invention may be disposed, for example, on the filter disposed on the inlet side and the outlet side or in between inside the processing container. As the filter, for example, a quartz filter or the like can be used. When the adsorbent of the present invention is used to remove carbon dioxide from the exhaust gas from a power plant, factory, or automobile, the exhaust gas or the like is introduced from the upper line, impurities are removed with a filter, and then carbon dioxide is selectively adsorbed and removed by the MOF of the present invention, and the nitrogen-enriched gas can be taken out from the lower line.

[0092] (Separation method) The CO of the present invention 2The method for separating gases using an adsorbent can separate one or more gases selected from the group consisting of helium, hydrogen, carbon dioxide, nitrogen, and methane from a mixed gas containing at least one type selected from the group consisting of carbon dioxide, hydrogen, oxygen, nitrogen, methane, ethane, ethylene, propane, propylene, butane, butene, sulfur fluoride, helium, carbon monoxide, nitric oxide, and water vapor by using the adsorbent of the present invention. In the present embodiment, it is preferable to separate carbon dioxide and / or nitrogen from one or more gases selected from the group consisting of nitrogen, carbon dioxide, and hydrocarbons. The hydrocarbons are not particularly limited, and examples thereof include methane, ethane, ethylene, propane, propylene, 1-butene, 2-butene, 2-methylpropene, dimethyl ether, acetylene, and the like.

[0093] CO of the present invention 2 The use of the adsorbent is not particularly limited. For example, it can be used as an adsorbent for adsorbing and separating CO from exhaust gases from power plants or factories (the proportion of CO in the exhaust gas is generally about 5 to 16% by volume, the exhaust gas temperature is generally about 50 to 75°C, and the pressure is about 100 kPa), or exhaust gases from automobiles (the proportion of CO in the exhaust gas is generally about 10% by volume, the exhaust gas temperature is generally about 70 to 90°C, and the pressure is about 100 kPa). 2 ), or as an adsorbent for adsorbing and separating CO from exhaust gases from automobiles (the proportion of CO in the exhaust gas is generally about 10% by volume, the exhaust gas temperature is generally about 70 to 90°C, and the pressure is about 100 kPa). 2 ), and the like. 2 for adsorbing and separating CO 2 from the exhaust gas.

Examples

[0094] Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The method for preparing samples and the method for measurement and evaluation in the present invention are as shown below.

[0095] (1) Powder X-ray diffraction (XRD) measurement method The XRD measurement of MOF was performed under the following conditions. Apparatus: MiniFlex600 manufactured by RIGAKU X-ray source: Cu-Kα ray Output setting: 40 kV·15 mA Divergence slit: 1.25° Incident-side solar slit: 2.5° Receiving-side solar slit: 2.5° X-ray extraction angle: 6° Ni filter: Thickness 0.015 mm Position of diffraction peak: 2θ (diffraction angle) Measurement range: 2θ = 3 - 40° Scan speed: 5° (2θ / min)

[0096] (2) Measurement of carbon dioxide adsorption amount The measurement of the carbon dioxide adsorption amount was carried out under the following conditions. (Pretreatment) Prior to the measurement of the adsorption amount of carbon dioxide and nitrogen, 50 mg of the powder to be measured was filled into the measurement cell, and the inside of the measurement cell was subjected to heat vacuum degassing treatment at 225 °C for 4 hours at 10 Pa using a pretreatment apparatus (BELPREP vacII, manufactured by MicrotracBEL Corporation). (Measurement of adsorption amount) Using the constant volume gas adsorption method with carbon dioxide as the adsorption gas, the adsorption isotherm at a temperature of 298 K was measured for the powder after pretreatment. For the measurement, a gas adsorption apparatus (Belsorp max, manufactured by MicrotracBEL Corporation) was used to measure the carbon dioxide adsorption amount at each equilibrium pressure from 0 kPa to 102 kPa of the equilibrium pressure.

[0097] (3) Measurement of nitrogen adsorption amount The measurement of the nitrogen adsorption amount was carried out under the following conditions. (Pretreatment) Prior to the measurement of the adsorption amount of nitrogen, 50 mg of the powder to be measured was filled into the measurement cell, and the inside of the measurement cell was subjected to heat vacuum degassing treatment at 200 °C for 4 hours at 10 Pa using a pretreatment apparatus (BELPREP vacII, manufactured by MicrotracBEL Corporation). (Measurement of adsorption amount) Using the constant volume gas adsorption method with nitrogen as the adsorption gas, the adsorption isotherm at a temperature of 77 K was measured for the powder after pretreatment. For the measurement, a gas adsorption apparatus (Belsorp max, manufactured by MicrotracBEL Corp.) was used to measure the nitrogen adsorption amount at each equilibrium pressure from 0 kPa to 102 kPa of equilibrium pressure.

[0098] (4) Single-component gas permeation test The single-component gas permeation test was carried out using the constant volume / valuable pressure method with the apparatus schematically shown in Fig. 1. The permeation side of the membrane (the lower side of membrane 1 in Fig. 1) was depressurized to 13 Pa (absolute pressure) or less, and gas was supplied at 35 kPa (G). The permeation coefficient was determined from the rate of increase in pressure on the permeation side when the differential pressure between the supply side and the permeation side of the membrane was 0.1 MPa. The temperature of the constant temperature bath 16 was set at 35 °C, and the permeation coefficient of the membrane at 35 °C was determined. From the ratio of the permeation coefficient of gas A to the permeation coefficient of gas B, the ideal separation factor α A / B was determined. In formula, the ideal separation factor α A / B = permeation coefficient of gas A / permeation coefficient of gas B.

[0099] Gas was supplied from the gas cylinder 18. The hand valve 17 and the valve 13 on the secondary side of the mass flow controller 5 were opened to supply gas through the mass flow controller 5. After storing the gas for the permeation test at 35 kPa (G) in the gas reservoir 3 for supplying and warming the gas, the valve 12 was closed and at the same time the valve 11 was opened to supply gas to the membrane. At this time, the valve 14 was open and the valve 15 was closed. To keep the pressure of the supplied gas constant, a constant amount of gas was supplied through the mass flow controller 5 with the valve 13 open, and the pressure was maintained constant by the pressure relief valve 6.

[0100] After the pressure increase rate measured by the pressure gauge 7 became steady, the permeation coefficient was calculated from the pressure increase rate, the volume, thickness, and membrane area from below the membrane to the valve 12. For the gas reservoir 8 for the permeating gas, it was filled with water and the internal volume was measured from the amount of water. For the piping part, the volume was calculated from the pipe length and inner diameter, and thus the volume from below the membrane to the valve 12 was calculated in advance. As the pressure gauge, an absolute pressure transducer (Baratron (registered trademark name) 0 - 10 Torr (626C11TBE) manufactured by MKS) was used.

[0101] The thickness was measured using a digital micrometer (MDC - 25M manufactured by Mitutoyo Corporation) at three locations, which were the center of the membrane to be measured and slightly inside from the edge of the membrane, and were selected evenly on the circumference. The average of a total of four locations was calculated. The area where the gas permeates was taken as the membrane area. The gases used were carbon dioxide (purity 99.9%, manufactured by Toho Oxygen Industry Co., Ltd.), methane (purity 99.999%, manufactured by Japan Fine Products), and hydrogen (purity 99.99%, manufactured by Showa Denko Gas Products Co., Ltd.).

[0102] (Pretreatment of the membrane) For the gas permeation test, while reducing the pressure of both the supply - side line and the permeation - side line, the membrane 1 set in the membrane module 2 was heated at 80°C or higher for 2 hours using a thermostatic bath. After 2 hours, the temperature of the thermostatic bath was lowered to 35°C and held for 1 hour to remove the water and gas dissolved and adsorbed in the membrane.

[0103] (5) Method for measuring the average particle size The measurement of the particle size distribution of MOF was carried out as follows. The synthesized powder was well - dispersed in a solvent, dropped on a sample stage, dried to prepare a sample, and photographed at an acceleration voltage of 10 kV using a scanning electron microscope (JEOL Ltd.: JSM - 6701F). For 30 randomly selected primary particles, image analysis was performed using image - analysis - type particle - size distribution measurement software Mac - View manufactured by Mount Tech Co., Ltd. to obtain the frequency (%) of the volume distribution with respect to the diameter of a circle (equivalent circle diameter) having an area equal to the projected area of the particle.

[0104] (6) Method for measuring average circularity coefficient The average circularity coefficient of the MOF was determined by image analysis using the image analysis type particle size distribution measurement software Mac-View manufactured by Mount Tech Co., Ltd. for 30 arbitrarily selected particles from the scanning electron microscope images taken in the same manner as the measurement of the primary particle size, and obtaining the circularity coefficient. The arithmetic mean of the circularity coefficients was taken as the average circularity coefficient. In the case of secondary particles formed by aggregation of small crystal particles, the average of the circularity coefficients of the secondary particles was taken as the average circularity coefficient. Here, the circularity coefficient is 4πS / L when the area of the two-dimensional projection image of the MOF particle is S and the perimeter of the particle is L. 2 It is the value represented by. (7) Method for measuring glass transition temperature The glass transition temperature was measured using a differential scanning calorimeter (DSC, DSC600 manufactured by Hitachi High-Tech Science Corporation). Approximately 10 mg of the resin sample was placed in an aluminum sample container and crimped, and heated from room temperature to 150 °C at a heating rate of 10 °C / min under a nitrogen flow of 30 mL / min. After holding the temperature for 1 minute, it was rapidly cooled to -150 °C at a setting of 100 °C / min and the temperature was held for 35 minutes, and then heated from -150 °C to 150 °C again at a rate of 10 °C / min. The inflection point of the DSC data obtained in the second heating was taken as the glass transition temperature.

[0105] [Example 1] 20.0 mL of methanol (manufactured by FUJIFILM Wako Pure Chemical Corporation) and 20.0 mL of pure water were mixed to prepare a mixed solvent. While stirring the mixed solvent, 16.3 mmol of zinc acetate dihydrate (manufactured by Sigma-Aldrich), 8.20 mmol of sodium oxalate (manufactured by FUJIFILM Wako Pure Chemical Corporation), and 32.4 mmol of 1,2,4-triazole (manufactured by Tokyo Chemical Industry Co., Ltd.) were added in this order. After adding 1,2,4-triazole, it was stirred and mixed at room temperature for 1 hour. Then, it was washed with pure water, dried at 100 °C under atmospheric pressure, and then vacuum dried at 130 °C overnight to obtain a product (Zn-MOF). As a result of measurement by the above powder X-ray diffraction (XRD), the XRD pattern shown in Fig. 2 was obtained, and it was confirmed that it was Zn-MOF. The maximum peak position was 2θ = 15.1°. The Zn-MOF obtained in Example 1 is referred to as MOF1.

[0106] (1) CO 2 Adsorption amount For MOF1, the carbon dioxide adsorption amount was measured by the above method. V = 3.7917 mmol / g (P = 100.02 kPa) (298K). (2) N 2 Adsorption amount For MOF1, the nitrogen adsorption amount was measured by the above method. V = 133.77 mL(STP) / g (P / Po = 0.1097) (77K) (3) Specific surface area and pore volume The specific surface area (SBET) and micropore volume (Vmicro) measured by the t-plot method are as follows. SBET = 567 m 2 / g Vmicro = 0.207 cm 3 / g (4) Average particle diameter and average circularity coefficient The average particle diameter measured by the above method was 1.19 μm, and the average circularity coefficient was 0.82. In addition, the results of graphing the frequency (%) of the volume distribution with respect to the equivalent circle diameter are shown in Fig. 3. The peaks of the frequency (%) were two, at an equivalent circle diameter of 1.23 μm and 4.93 μm. The ratio of the particle diameters of the mode value in the large particle diameter region and the mode value in the small particle diameter region was 4.0.

[0107] [Example 2] 4.0 mL of methanol (manufactured by FUJIFILM Wako Pure Chemical Corporation) and 16.0 mL of pure water were mixed. To the methanol-water mixture under stirring, 8.14 mmol of 1,2,4-triazole (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.04 mmol of sodium oxalate (manufactured by FUJIFILM Wako Pure Chemical Corporation), and 4.07 mmol of zinc acetate dihydrate (manufactured by Sigma-Aldrich) (solubility 40 g / 100 cm 3(1) was added in order. After adding zinc acetate dihydrate, the mixture was stirred at room temperature for 1 hour. Then, it was washed with pure water. After drying at 100 °C under atmospheric pressure, it was vacuum dried at 130 °C overnight to obtain the product (MOF2). The carbon dioxide adsorption amount was measured in the same manner as in Example 1. (1) CO 2 Adsorption amount For MOF2, the carbon dioxide adsorption amount was measured by the above method. V = 3.94 mmol / g (P = 100.07 kPa) (298 K)

[0108] [Example 3] 4.0 mL of methanol (manufactured by FUJIFILM Wako Pure Chemical Corporation) and 16.0 mL of pure water were mixed. To the stirred methanol - water mixture, 4.07 mmol of zinc acetate dihydrate (manufactured by Sigma - Aldrich), 8.14 mmol of 1,2,4 - triazole (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2.04 mmol of sodium oxalate (manufactured by FUJIFILM Wako Pure Chemical Corporation) were added in order. After adding sodium oxalate, the mixture was stirred at room temperature for 1 hour. Then, it was washed with pure water. After drying at 100 °C under atmospheric pressure, it was vacuum dried at 130 °C overnight to obtain the product (MOF3). In the same manner as in Example 1, the carbon dioxide adsorption amount, nitrogen adsorption amount, surface area, and pore volume were measured.

[0109] (1) CO 2 Adsorption amount For MOF3, the carbon dioxide adsorption amount was measured by the above method. V = 3.77 mmol / g (P = 100.11 kPa) (298 K) (2) N 2 Adsorption amount For MOF3, the nitrogen adsorption amount was measured by the above method. V = 123.04 mL(STP) / g (P / Po = 0.0964) (77 K) (3) Surface area and pore volume The surface area (SBET) and micropore volume (Vmicro) measured by the t - plot method are as follows. SBET = 531 m 2 / g Vmicro = 0.189 cm 3 / g

[0110] [Example 4] Weighed 0.3054 g of MOF1 dried at 150°C for 3 hours, added 0.212 g of poly(dimethylsiloxane), (hydroxy-terminated silicone resin P-1, viscosity; 18,000 - 22,000 cSt, manufactured by Sigma-Aldrich Japan), stirred for 15 minutes with a kneader (manufactured by Shinky Co., Ltd.), and then defoamed for 1 minute. Added 0.872 g of hexane (manufactured by Fujifilm Wako Pure Chemical Corporation) thereto, dispersed it in an ultrasonic cleaner for 30 minutes, and then added 0.069 g of tetraethyl orthosilicate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.015 g of dibutyltin dilaurate (manufactured by Sigma-Aldrich Japan). After that, it was stirred at room temperature to prepare a mixed solution. After dropping 0.47 g of the prepared mixed solution into a Teflon (registered trademark) petri dish with an inner diameter of 30 mm, the Teflon (registered trademark) petri dish was placed in a vacuum dryer, evacuated to volatilize hexane, then the petri dish was taken out and left standing at room temperature in a draft for 24 hours to cure the silicone resin. The film was peeled off from the Teflon (registered trademark) petri dish to obtain an organic-inorganic hybrid membrane (M-1). The film thickness was 142 μm. The solid content concentration of the mixed solution used for film formation was 40.8 mass%, and the content of Zn-MOF in the organic-inorganic hybrid membrane (M-1) was 50.8 mass%. Table 1 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases at 35°C for the organic-inorganic hybrid membrane (M-1). Since MOF1 has a bimodal particle size distribution, an organic-inorganic hybrid membrane containing more than 50 mass% of MOF could be formed. Due to the bimodal particle size distribution, it is considered that the smaller-sized MOF filled the gaps between the larger-sized MOF, increasing the overall filling amount. In addition, because the content of MOF in the organic-inorganic hybrid membrane (M-1) increased, high H 2, it is considered that the transmission coefficient of He was shown. Also, by including MOF1, the transmission coefficient of CO increased compared to M-2, and the ideal separation factor of CO 2 / N 2 2 , CO 2 / CH 4 increased (Comparative Example 1).

[0111] [Comparative Example 1] (Silicone resin membrane (M-2)) 2.0 g of hexane (manufactured by FUJIFILM Wako Pure Chemical Corporation) and 0.63 g of poly(dimethylsiloxane), (hydroxy-terminated silicone resin P-1, viscosity; 18,000 - 22,000 cSt, manufactured by Sigma-Aldrich Japan) were mixed uniformly using a stir bar, and then 0.14 g of tetraethyl orthosilicate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.015 g of dibutyltin dilaurate (manufactured by Sigma-Aldrich Japan) were added and mixed well. The obtained mixed solution was dropped in its entirety into a Teflon (registered trademark) petri dish with an inner diameter of 30 mm. The Teflon (registered trademark) petri dish was placed in a vacuum dryer, and after hexane was volatilized, it was left standing in a draft overnight to cure the matrix resin (P-1). The membrane was peeled off from the Teflon (registered trademark) petri dish to obtain a silicone resin membrane (M-2). The membrane thickness was 159 μm. The glass transition temperature (Tg) of the silicone resin membrane (M-2) was -124°C. Table 1 shows the results of measuring the transmission coefficients and ideal separation factors of various gases at 35°C for the silicone resin membrane (M-2).

[0112]

Table 1

[0113] [Example 5] ​Weighed 0.2009 g of MOF1 dried at 150 °C for 2 hours, mixed it with 1.000 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), dispersed it using an ultrasonic cleaner, and then added 0.300 g of a silicone rubber precursor (TSE382-C (manufactured by Momentive Performance Materials Japan G.K.) (hereinafter may be referred to as "TSE382").). Further, 0.677 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation) was added, and the mixture was stirred and mixed at room temperature. 0.993 g of the obtained liquid was dropped into a Teflon (registered trademark) petri dish with an inner diameter of 30 mm, air-dried for 64 hours, and then heated at 120 °C for 1 hour to cure the silicone resin. The cured film was peeled off from the Teflon (registered trademark) petri dish to obtain a film (M-3) composed of a matrix resin (silicone resin derived from TSE382: P-2) and MOF1. The thickness of M-3 was 166 μm. The content of MOF1 in M-3 was 40.1% by mass. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases in M-3 at 35 °C. The glass transition temperature (Tg) of the silicone resin P-2 prepared in the same manner except that MOF1 was not mixed was -126 °C.

[0114] [Example 6] 4.0 mL of methanol (manufactured by Fujifilm Wako Pure Chemical Corporation) and 16.0 mL of pure water were mixed. To the stirring methanol-water mixture, 2.04 mmol of sodium oxalate (manufactured by Fujifilm Wako Pure Chemical Corporation), 4.07 mmol of zinc acetate dihydrate (manufactured by Sigma-Aldrich), and 8.14 mmol of 1,2,4-triazole (manufactured by Tokyo Chemical Industry Co., Ltd.) were added in sequence. After adding 1,2,4-triazole, the mixture was stirred and mixed at room temperature for 1 hour. Then, it was washed with pure water. After drying at 100 °C under atmospheric pressure and then vacuum drying at 130 °C overnight, a product (MOF5) was obtained. In the same manner as in Example 1, the carbon dioxide adsorption amount, nitrogen adsorption amount, surface area, and pore volume were measured.

[0115] (1) CO 2 Adsorption amount For MOF5, the carbon dioxide adsorption amount was measured by the above method. V = 3.747 mmol / g (P = 100.2 kPa) (298K) (2) N 2 Adsorption amount For MOF5, the nitrogen adsorption amount was measured by the above method. V = 119.45 mL(STP) / g (P / Po = 0.0808) (77K) (3) Specific surface area and pore volume The specific surface area (SBET) and micropore volume (Vmicro) measured by the t-plot method are as follows. SBET = 514 m 2 / g Vmicro = 0.185 cm 3 / g

[0116] [Example 7] 4.0 mL of methanol (manufactured by Fujifilm Wako Pure Chemical Corporation) and 16.0 mL of pure water were mixed. To the stirred methanol-water mixture, 2.04 mmol of sodium oxalate (manufactured by Fujifilm Wako Pure Chemical Corporation), 8.14 mmol of 1,2,4-triazole (manufactured by Tokyo Chemical Industry Co., Ltd.), and 4.07 mmol of zinc acetate dihydrate (manufactured by Sigma-Aldrich) were added in order. After adding zinc acetate dihydrate, the mixture was stirred and mixed at room temperature for 1 hour. Then, it was washed with pure water. After drying at 100 °C under atmospheric pressure and then vacuum drying at 130 °C overnight, the product (MOF6) was obtained. In the same manner as in Example 1, the carbon dioxide adsorption amount, nitrogen adsorption amount, specific surface area, and pore volume were measured.

[0117] (1) CO 2 Adsorption amount For MOF6, the carbon dioxide adsorption amount was measured by the above method. V = 3.917 mmol / g (P = 100.21 kPa) (298K) (2) N 2 Adsorption amount For MOF6, the nitrogen adsorption amount was measured by the above method. V = 123.95 mL(STP) / g (P / Po = 0.0892) (77K) (3) Specific surface area and pore volume The specific surface area (SBET) and micropore volume (Vmicro) measured by the t-plot method are as follows. SBET = 518 m 2 / g Vmicro = 0.190 cm 3 / g

[0118] [Example 8] Weighed 0.2034 g of MOF3 dried at 150°C for 2 hours, mixed it with 1.035 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), dispersed it using an ultrasonic cleaner, then added 0.299 g of a silicone rubber precursor (TSE382-C, manufactured by Momentive Performance Materials Japan LLC), further added 0.717 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), stirred it with a bubble breaker (manufactured by Shinky Co., Ltd.) for 5 minutes, defoamed it for 1 minute, and then stirred and mixed it with a stir bar at room temperature. The obtained liquid was dropped at 0.898 g into a Teflon (registered trademark) petri dish with an inner diameter of 30 mm, air-dried in a draft for 64 hours, and then heated at 120°C for 2 hours to cure the silicone resin. The cured film was peeled off from the Teflon (registered trademark) petri dish to obtain a film (M-6) composed of a matrix resin (silicone resin derived from TSE382: P-2) and MOF3. The thickness of M-6 was 153 μm. The content of MOF3 in M-6 was 40.5 mass%. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases in M-6 at 35°C.

[0119] [Example 9] Weighed 0.201 g of MOF5 dried at 150 °C for 2 hours, mixed it with 1.024 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), dispersed it using an ultrasonic cleaner, then added 0.304 g of a silicone rubber precursor (TSE382-C (manufactured by Momentive Performance Materials Japan G.K.)), further added 0.626 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), stirred it with a bubble pick mixer (manufactured by Shinky Co., Ltd.) for 5 minutes, defoamed it for 1 minute, and then stirred and mixed it with a stir bar at room temperature. The resulting liquid was dropped at 0.833 g into a Teflon (registered trademark) petri dish with an inner diameter of 30 mm, air-dried in a draft for 64 hours, and then heated at 120 °C for 2 hours to cure the silicone resin. The cured film was peeled off from the Teflon (registered trademark) petri dish to obtain a film (M-7) composed of a matrix resin (TSE382-derived silicone resin: P-2) and MOF5. The thickness of M-7 was 154 μm. The content of MOF5 in M-7 was 39.8 mass%. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases in M-7 at 35 °C.

[0120] [Example 10] Weighed 0.204 g of MOF6 dried at 150 °C for 2 hours, mixed it with 1.029 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), dispersed it using an ultrasonic cleaner, then added 0.301 g of silicone rubber precursor (TSE382-C, manufactured by Momentive Performance Materials Japan G.K.), further added 0.616 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation), stirred it with a bubble pick mixer (manufactured by Shinki Co., Ltd.) for 5 minutes, defoamed it for 1 minute, and then stirred and mixed it with a stir bar at room temperature. The obtained liquid was dropped at 0.916 g into a Teflon (registered trademark) petri dish with an inner diameter of 30 mm, air-dried in a draft for 64 hours, and then heated at 120 °C for 2 hours to cure the silicone resin. The cured film was peeled off from the Teflon (registered trademark) petri dish to obtain a film (M-8) composed of a matrix resin (TSE382-derived silicone resin: P-2) and MOF6. The thickness of M-8 was 159 μm. The content of MOF6 in M-8 was 40.3 mass%. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases of M-8 at 35 °C.

[0121] [Example 11] Put 19.03 g of 1-butanol (manufactured by Fujifilm Wako Pure Chemical Corporation) and 1.603 g of Pebax 2533 SA (manufactured by Arkema, hereinafter sometimes referred to as "Pebax") into a Teflon (registered trademark) inner cylinder, put the inner cylinder into an autoclave and sealed it, then heated it at 130 °C for 3 hours to dissolve Pebax. Added 2.978 g of MOF1 dried under reduced pressure at 130 °C for 3 hours, stirred it for 5 hours, and then performed ultrasonic treatment to remove bubbles. The obtained 8.5 g of the mixed solution was spread on a PFA (perfluoroalkoxy fluororesin) petri dish with an inner diameter of 100 mm, left standing for 4 days, the solvent was evaporated at room temperature and atmospheric pressure, and then the film was peeled off from the PFA petri dish to obtain a film (M-9) composed of a matrix resin (Pebax 2533 SA: P-3) and MOF1. The thickness of M-9 was 173 μm. The content of MOF1 in M-9 was 65.0 mass%. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases of M-9 at 35 °C.

[0122] [Example 12] In the same manner as in Example 11, a film (M-10) composed of MOF1 and a matrix resin (Pebax 2533 SA: P-3) was obtained. The thickness of M-10 was 166 μm. The content of MOF1 in M-10 was 65.0% by mass. For M-10, the pretreatment of the film was carried out in the same manner as in Example 11 except that the film was placed in a petri dish and heated in an oven at 100 °C for 24 hours, and the permeation coefficients and ideal separation coefficients of various gases at 35 °C for M-10 were measured. The results are shown in Table 2.

[0123] [Comparative Example 2] MOF was prepared by a mechanochemical method. Specifically, it was carried out by the following method. 0.774 mmol of zinc hydroxycarbonate (manufactured by Strem Chemicals, solubility less than 0.05 g), 4.72 mmol of oxalic acid (manufactured by Fujifilm Wako Pure Chemical Corporation), 10 ml of methanol (manufactured by Fujifilm Wako Pure Chemical Corporation), 1 mL of 5M potassium hydroxide aqueous solution (manufactured by Fujifilm Wako Pure Chemical Corporation), and 50 zirconia balls with a diameter of 10 mm were placed in a zirconia ball mill container with a capacity of 250 ml, covered, and then kneaded at a rotation speed of 150 rpm for 2 hours by a planetary ball mill P-6 (manufactured by Fritsch Japan Co., Ltd.). The kneading by the ball mill was carried out at room temperature (25 °C), and no heating or cooling was performed. After the kneaded powder was washed three times with 40 ml of pure water, it was dried under reduced pressure at 40 °C to obtain a powder of MOF (MOF4). When powder X-ray diffraction (XRD) was performed on MOF4, the peak pattern shown in Fig. 4 was obtained. The maximum peak position of MOF4 was 2θ = 15.1°. The primary particle diameter of MOF4 was 0.27 μm, and the average circularity coefficient was 0.88. At 77 K, when the nitrogen adsorption amount of MOF4 was measured, the nitrogen adsorption amount at a relative pressure P / P 0 = 0.1 was 128 ml(STP) / g. The result of graphing the frequency (%) of the volume distribution with respect to the equivalent circle diameter is shown in Fig. 5. The peak of the frequency (%) was one at an equivalent circle diameter of 0.37 μm. The average particle diameter was 0.27 μm, and the average circularity coefficient was 0.88.

[0124] [Comparative Example 3] Except for using MOF4 instead of MOF1, M-4 composed of matrix resin (silicone resin derived from TSE382: P-2) and MOF4 was obtained in the same manner as in Example 5. The thickness of M-4 was 211 μm. The content of MOF4 in M-4 was 40.0% by mass. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases in M-4 at 35°C.

[0125] [Comparative Example 4] 2.0 g of TSE382 was mixed and dissolved in 2.0 g of toluene (manufactured by Fujifilm Wako Pure Chemical Corporation) using "AR-250" manufactured by THINKY. The obtained solution was poured onto a cellulose acetate membrane filter with a pore diameter of 0.45 μm, pulled with an applicator having a gap width of 6 mils and cast, and then dried at 50°C for 5 hours under a nitrogen stream to obtain a membrane (M-5) composed of silicone resin derived from TSE382: P-2. The thickness of the silicone resin portion calculated from the cross-sectional SEM image of M-5 was 8.7 μm. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases in M-5 at 35°C.

[0126] Comparative Example 5 Except for not mixing MOF1, M-11 composed only of matrix resin (Pebax 2533 SA: P-3) was obtained in the same manner as in Example 11. The thickness of M-11 was 69 μm. Table 2 shows the results of measuring the permeation coefficients and ideal separation coefficients of various gases in M-11 at 35°C.

[0127] Comparative Example 6 M-12 consisting of only a matrix resin (Pebax 2533 SA:P-3) was obtained in the same manner as in Example 11, except that MOF1 was not mixed. The thickness of M-12 was 86 μm. The permeability coefficients and ideal separation coefficients of various gases at 35° C. of M-12 were measured in the same manner as in Example 11, except that the membrane pretreatment for M-12 was performed by placing the membrane in a petri dish and heating it in an oven at 100° C. for 24 hours. The results are shown in Table 2.

[0128] [Table 2]

[0129] From Table 2, 100 cm of water at 25°C 3 The organic-inorganic hybrid membrane using the metal-organic framework synthesized in solution using a zinc compound with a solubility of 0.05 g or more in water had higher permeability than the organic-inorganic hybrid membrane using the metal-organic framework synthesized by the mechanochemical method. This is believed to be because the manufacturing method of the present invention produced a metal-organic framework with a uniform zinc distribution and fewer impurities. [Industrial Applicability]

[0130] According to the present invention, a method for producing Zn-MOFs at low cost in a short time can be provided. In addition, the method of the present invention can be used to mass-produce Zn-MOFs, making it a highly productive method. The Zn-MOFs produced by the present invention can be applied to membranes in membrane separation processes, and can be used to separate harmful greenhouse gases, particularly carbon dioxide (CO 2 ) from industrial waste efficiently, making this a technology of great industrial value. [Explanation of symbols]

[0131] 1 membrane 2. Separation Membrane Module 3 Gas reservoir for keeping supply gas warm 4. Pressure gauge 5 Mass Flow Controller 6 - way pressure valve 7 - baratron pressure gauge 8 - gas reservoir for permeating gas 9 - liquid nitrogen trap 10 - vacuum pump 11, 12, 13, 14, 15 - valves 16 - constant temperature bath 17 - valve (hand - held valve) 18 - gas cylinder

Claims

1. A method for preparing a metal organic framework comprising zinc ions coordinated with optionally substituted triazolates and oxalates, comprising the steps of: ３ A method for preparing a metal-organic framework using a zinc compound having a solubility in water of 0.05 g or more.

2. The method for producing a metal-organic framework according to claim 1 , wherein the zinc compound, the triazole compound which may have a substituent, and the oxalate compound are added to a solvent containing water, and reacted with each other.

3. The method for producing a metal-organic framework according to claim 2, wherein 0.8 to 3 mol of an optionally substituted triazole compound and 0.4 to 0.6 mol of an oxalate compound are added relative to 1 mol of the zinc compound.

4. The method for producing a metal-organic framework according to claim 3, wherein the total concentration of the zinc compound, the triazole compound and the oxalate compound in the solvent is 0.1 to 10 mol / L.

5. The method of claim 2 , wherein the solvent further comprises an alcohol.

6. The method for producing a metal-organic framework according to claim 5 , wherein the ratio (volume ratio) of alcohol to water in the solvent is 1:1, and the ratio of water is 0.3 to 20.

7. The method for producing a metal-organic framework according to claim 5, wherein the alcohol is methanol and / or ethanol.

8. The method for producing the metal-organic framework according to claim 2, wherein the reaction is stirred at 0 to 100° C. for 5 minutes or more.

9. The method for preparing the metal-organic framework of claim 1 , wherein the zinc compound is zinc acetate.

10. The method for preparing a metal-organic framework according to claim 2, wherein the triazole compound is 1,2,4-triazole.

11. 3. The method for producing a metal-organic framework according to claim 2, further comprising: a zinc compound solution preparation step of preparing a solution of the zinc compound; and an addition step of adding an optionally substituted triazole compound and an oxalate compound to the zinc compound solution.

Images