JP7324444B2 - Organic porous material, manufacturing method thereof, adsorbent and organic porous column - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic porous material and a method for producing the same. The present invention also relates to an adsorbent containing an organic porous material and an organic porous column.

An organic porous material having a resin skeleton and pores is known. Patent Document 1 discloses an organic porous material having a melamine resin skeleton. The porous body of Patent Document 1 is obtained by mixing a mixture of reactive polycondensation resins and polymer particles and gelling the mixture.

Japanese Patent Publication No. 2007-529619

Considering the use of organic porous bodies for various applications, a method for producing organic porous bodies with a high degree of freedom in pore design is required. However, conventional methods cannot achieve sufficient degrees of freedom. In the method of Patent Document 1, polymer particles such as latex particles are used as a pore template, and polymerization proceeds in the voids between the particles to form a skeleton. Therefore, the pore size distribution is broad, and the porous body of Patent Document 1 is not suitable for use in, for example, adsorption columns and separation columns. Further, in the method of Patent Document 1, it is difficult to form a porous body having a hierarchical porous structure of macropores and mesopores or a porous body having a co-continuous structure of skeleton and macropores.

An object of the present invention is to provide a method for producing an organic porous material with a high degree of freedom in pore design, and an organic porous material achievable by the method.

The present invention
melamine and aldehyde monomers and/or oligomers of melamine and aldehyde monomers;
a phase separation inducer;
In a solution system comprising a first solvent,
Formation of a melamine resin and spinodal decomposition of the solution system proceed by condensation polymerization of the monomer and/or the oligomer,
step (I) of forming a wet gel composed of said melamine resin-rich skeletal phase and said first solvent-rich solution phase;
By drying the wet gel, a skeleton based on the melamine resin is formed from the skeleton phase, macropores are formed from the solution phase, and an organic porous body having the skeleton and the macropores is formed. a step (II) of obtaining
A method for producing an organic porous material,
I will provide a.

Viewed from another aspect, the present invention provides
having a melamine resin-based skeleton, macropores, and mesopores having openings on the surface of the skeleton;
The mesopores constitute a hierarchical porous structure together with the macropores, which are voids between the skeletons,
The pore diameter mode of the macropores is 0.1 to 10 μm,
an organic porous material in which the pore size mode of the mesopores is 2 to 40 nm;
I will provide a.

Viewed from another aspect, the present invention provides
an adsorbent comprising the organic porous material of the present invention;
I will provide a.

Viewed from another aspect, the present invention provides
comprising the organic porous body of the present invention and a housing,
an organic porous column in which the organic porous body is accommodated in the housing;
I will provide a.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic porous body with a high degree of freedom of pore design, and the organic porous body which can be achieved by the said method are provided.

FIG. 1 is a schematic diagram for explaining the pore size distribution of macropores of an organic porous body. FIG. 2A is a diagram showing observation results of the skeleton and macropores of Samples 1A to 1D and 1F of Examples by a scanning electron microscope (hereinafter referred to as "SEM"). FIG. 2B is a diagram showing the results of SEM observation of the hierarchical porous structure of macropores and mesopores for sample 1C of Example. FIG. 3 is a diagram showing the results of SEM observation of the skeleton and macropores of samples 2A to 2E of the example. FIG. 4 is a graph showing the results of pore size distribution measurement of macropores for Samples 1D and 1E of Examples. FIG. 5 is a graph showing the results of pore size distribution measurement of macropores for samples 1D and 1E of Examples. FIG. 6 is a graph showing nitrogen adsorption and desorption isotherms of samples 1C to 1E, 2A, and 2C of Examples. FIG. 7 is a graph showing the results of pore size distribution measurement for samples 1C to 1E, 2A, and 2C of Examples. FIG. 8 is a graph showing nitrogen adsorption and desorption isotherms of samples 2C and 2CH of the example. FIG. 9 is a graph showing the results of pore size distribution measurement for Samples 2C and 2CH of Examples. FIG. 10 is a graph showing nitrogen adsorption and desorption isotherms of Samples 3A, 3AL, 3B, and 3BL of Examples. FIG. 11 is a graph showing the results of pore size distribution measurement for samples 3A, 3AL, 3B, and 3BL of Examples. FIG. 12 is a graph showing nitrogen adsorption and desorption isotherms of samples 1C and 4A to 4E of the example. FIG. 13 is a graph showing the results of pore size distribution measurement for samples 1C and 4A to 4E of Examples. FIG. 14 is a graph showing nitrogen adsorption and desorption isotherms of samples 4F to 4M of the example. FIG. 15 is a graph showing the results of pore size distribution measurement for Samples 4F to 4M of Examples. FIG. 16 is a graph showing nitrogen adsorption and desorption isotherms of samples 4F, 4N to 4R of the example. FIG. 17 is a graph showing the results of pore size distribution measurement for samples 4F, 4N to 4R of the example. FIG. 18 is a graph showing nitrogen adsorption and desorption isotherms of samples 4F, 4S to 4Z, 4α, and 4β of the example. FIG. 19 is a graph showing the results of pore size distribution measurement for samples 4F, 4S to 4Z, 4α, and 4β of Examples. FIG. 20 is a graph showing the nitrogen adsorption and desorption isotherms of Samples 5A to 5D of Examples. FIG. 21 is a graph showing the results of pore size distribution measurement for Samples 5A to 5D of Examples. FIG. 22 is a graph showing nitrogen adsorption and desorption isotherms of samples 4F and 6A to 6C of the example. FIG. 23 is a graph showing the results of pore size distribution measurement for Samples 4F and 6A to 6C of Examples. FIG. 24 is a graph showing nitrogen adsorption and desorption isotherms of samples 4F, 6D to 6G of the example. FIG. 25 is a graph showing the results of pore size distribution measurement for samples 4F and 6D to 6G of Examples. FIG. 26 is a graph showing nitrogen adsorption and desorption isotherms of samples 4F and 6H to 6J of the example. FIG. 27 is a graph showing the results of pore size distribution measurement for samples 4F and 6H to 6J of Examples. FIG. 28 is a graph showing nitrogen adsorption and desorption isotherms of samples 1D, 6K to 6N of the example. FIG. 29 is a graph showing the results of pore size distribution measurement for samples 1D and 6K to 6N of Examples. FIG. 30 is a graph showing nitrogen adsorption and desorption isotherms of samples 1C and 7A to 7D of the example. FIG. 31 is a graph showing the results of pore size distribution measurement for samples 1C and 7A to 7D of Examples. FIG. 32 is a graph showing breakthrough curves of columns C1 and C2 of the example. FIG. 33 is a graph showing the metal ion removal rate and integrated recovery rate of the columns C1 and C2 of the example. FIG. 34 is a graph showing an example of a separation curve of a high performance liquid chromatograph (hereinafter referred to as "HPLC") using the column C3 of Example.

In this specification, pores with a pore size (pore size) of more than 50 nm are referred to as macropores, and pores with a pore size of 2 nm or more and 50 nm or less are referred to as mesopores, based on the proposal by IUPAC. A pore having a pore diameter of less than 2 nm is generally referred to as a micropore. The pore size and average pore size of the pores can be determined by a general pore distribution measurement method selected based on the size of the expected pore size and average pore size. The pore distribution measurement method is, for example, a mercury intrusion method for macropores and a nitrogen gas adsorption method for mesopores.

(Method for producing organic porous material)
[Step (I)]
The solution system of step (I) includes melamine monomers and aldehyde monomers and/or oligomers of melamine monomers and aldehyde monomers, a phase separation inducer, and a first solvent.

A melamine monomer is a monomer that has a melamine skeleton and is capable of condensation polymerization with an aldehyde monomer through the amino group of the monomer. Melamine monomers are, for example, melamine and its derivatives. Examples of derivatives are methylated melamine, etherified melamine, acrylated melamine, acetylated melamine, methylolmelamine and benzoylmelamine. The melamine monomer is preferably melamine. The solution system may contain two or more melamine monomers.

An aldehyde monomer is a monomer that has an aldehyde group and is capable of condensation polymerization with a melamine monomer. Aldehyde monomers are, for example, formaldehyde, acetaldehyde, propionaldehyde, acrolein, benzaldehyde, glyoxal, furfural, preferably formaldehyde. The monomers exemplified above may have a substituent. Substituents are typically attached to carbon atoms other than those constituting the aldehyde group. Examples of substituents are halogen groups such as chloro, bromo and iodo groups, carboxylic acid groups, amino groups, epoxy groups, hydroxy groups, thiol groups, phosphine groups, cyano groups, azo groups and imino groups. The solution system may contain two or more aldehyde monomers.

Oligomers of melamine and aldehyde monomers are condensation products of both monomers, eg methylolmelamine. However, the oligomer is not limited to the above examples as long as it can form a melamine resin in step (I). Incidentally, the oligomer is usually a condensate of 100 or less monomers. The solution system may contain only oligomers of melamine monomers and aldehyde monomers as raw materials for the melamine resin. The solution system may contain two or more such oligomers.

The phase separation inducer is a component that induces and promotes spinodal decomposition in a solution system that proceeds with the formation of a melamine resin by condensation polymerization of the above monomers (melamine monomers and aldehyde monomers) and/or oligomers. The phase separation inducing component is, for example, a polymer compound that dissolves in the first solvent. A polymer compound may be a homopolymer. Examples of phase separation inducers are polyethylene oxide (PEO), polypropylene oxide, polyvinylpyrrolidone, polyacrylic acid amide, polyacrylic acid, polymethacrylic acid, sodium polystyrene sulfonate and polyallylamine. The phase separation inducer may be a copolymer having two or more structural units of the polymer compounds exemplified above, or may be a surfactant such as sodium dodecylsulfate and cetyltrimethylammonium chloride. The phase separation inducer is preferably PEO.

The number average molecular weight of the phase separation inducer such as PEO is, for example, 1000 to 400,000, and may be 10,000 to 300,000, 50,000 to 250,000, and further 100,000 to 200,000.

The first solvent dissolves the above monomers and/or oligomers and the phase separation inducer contained in the solution system. Examples of first solvents are hydrophilic solvents and water. A hydrophilic solvent is a solvent that can be mixed with water in any mixing ratio. Examples of first solvents are water, alcohols, amides, ethers, dimethylsulfoxide and mixed solvents thereof. However, since spinodal decomposition tends to be suppressed by adding water, the content of water in the first solvent containing water is preferably 5% by weight or less, and may be 2% by weight or less. . The solution system may be substantially free of water or free of water. In the present specification, "substantially free" means that the content is, for example, 1% by weight or less, preferably 0.5% by weight or less. Examples of alcohols are methanol, ethanol, n-propanol, 2-propanol, n-butanol, triethylene glycol. Examples of amides are N,N'-dimethylacetamide and N,N'-dimethylformamide (DMF). Examples of ethers are tetrahydrofuran and dioxane. The first solvent is not limited to the above examples.

When the solution system contains a melamine monomer, the concentration of the melamine monomer in the solution system is, for example, 0.5-30% by weight, and may be 1-20% by weight, 2-10% by weight.

When the solution system contains the oligomer, the concentration of the oligomer in the solution system may be, for example, 1-40% by weight, 2-30% by weight, 5-20% by weight.

The molar ratio of the aldehyde component to the melamine component in the solution system (reaction molar ratio: aldehyde component/melamine component) is, for example, 1-12, and may be 1-10 or 4-8. The reaction molar ratio can be calculated from the molar amount of each monomer contained in the solution system, and the oligomer composition (ratio of melamine component and aldehyde component in the oligomer) and concentration.

The concentration of the phase separation inducing agent in the solution system is, for example, 0.01-15% by weight, and may be 1-10% by weight, or 0.5-3% by weight.

The solution system may contain melamine monomers and aldehyde monomers and/or monomer A copolymerizable with the above oligomers. Monomer A is selected from halogen groups such as chloro, bromo and iodo groups, carboxylic acid groups, amino groups, epoxy groups, hydroxy groups, thiol groups, phosphine groups, cyano groups, azo groups and imino groups. It may have at least one group. Examples of monomers A are urea, guanidine, ethyleneimine, phenol, mercaptotriazine and guanamine and derivatives thereof. The solution system can, for example, contain monomer A in the range of 30% by weight or less, preferably 10% by weight or less. When the solution system contains monomer A, the melamine resin formed in step (I) may have structural units derived from monomer A.

The solution system may contain additives. Examples of additives are polymerization catalysts. Examples of polymerization catalysts are acid catalysts. Examples of acid catalysts are inorganic acids such as hydrochloric acid, nitric acid and nitric acid, and organic acids such as trifluoroacetic acid (TFA) and trifluoromethanesulfonic acid. The solution system may contain the polymerization catalyst at a concentration of, for example, 0.1 to 5% by weight, depending on the amount of the first solvent used.

In the step (I), condensation polymerization of the above monomers and/or oligomers is allowed to proceed with formation of a melamine resin and spinodal decomposition of a solution system, resulting in a skeleton phase rich in the melamine resin and a solution phase rich in the first solvent. forms a wet gel consisting of

Spinodal decomposition is a form of phase separation that can occur in polymerization solution systems. This phase separation process proceeds with the formation of a resin by polymerization. Spinodal decomposition progresses as the concentration difference (concentration gradient) of the resin induced by polymerization expands over time. In this respect, it differs from phase separation based on nucleation and subsequent formation of resin particles (nucleation-growth process). The widened concentration difference is fixed by the progress of polymerization to form a wet gel composed of a skeletal phase and a solution phase. This formation reaction is a form of sol-gel method combined with spinodal decomposition.

The degree of freedom of pore control in the organic porous material can be improved by the solution system spinodal decomposition that progresses with the formation of the melamine resin. Examples of aspects that can be achieved by improving the degree of freedom are shown in (1) to (4) below. Examples (1) to (4) can be achieved alone or in any combination.

(1) Forming a wet gel having a co-continuous structure of the skeleton phase and the solution phase in step (I), and obtaining an organic porous body having a co-continuous structure of the skeleton and macropores in step (II). good too. A co-continuous structure is a three-dimensional structure also called a co-continuous structure or a bi-continuous structure by those skilled in the art. Each phase constituting the co-continuous structure has a continuous three-dimensional network structure and is in a mutually entangled state. In the nucleation-growth process, a large number of resin particles generated simultaneously and multiple times stochastically aggregate to form a porous structure, so a porous body having a co-continuous structure of skeleton and macropores cannot be obtained. .

(2) An organic porous body having macropores and mesopores having openings on the surface of the skeleton (hereinafter simply referred to as "mesopores") may be obtained. Specifically, in step (I), a wet gel composed of a skeletal phase having pores (original mesopores) with openings on the surface of the skeletal phase and a solution phase is formed, and in step (II) and forming mesopores from the pores to obtain an organic porous material having macropores and mesopores. An organic porous body having a hierarchical porous structure of macropores and mesopores may be obtained. The hierarchical porous structure of macropores and mesopores means a porous structure in which macropores and mesopores have independent pore size distributions within the same porous body.

(3) It is possible to improve the degree of freedom in controlling the diameter of the macropores of the organic porous material. The pore size mode (mode) of macropores can be controlled, for example, in the range of 0.1 to 100 μm, particularly 0.1 to 10 μm. In addition, the pore diameter mode of macropores (hereinafter simply referred to as "macropore diameter A" or "pore diameter A") is defined as the pore diameter mode of mesopores (hereinafter simply referred to as "mesopore diameter B" or "pore diameter B”) can also be controlled independently. Based on the possibility of independent control, it is also possible to control, for example, the ratio A/B of the pore diameter A of the macropores to the pore diameter B of the mesopores.

(4) The pore size distribution of the macropores of the organic porous material can be reduced. For example, macropores having a pore size distribution of 8 μm or less (“pore size distribution” will be described in detail later) can be obtained by evaluating the pore size distribution of an organic porous material.

The state of progress of spinodal decomposition and the degree of freedom of pore control in step (I) are typically determined by the molecular weight of the phase separation inducer, the concentration of the phase separation inducer in the solution system, the temperature at which step (I) is performed, and the / Or it can be controlled by execution time.

The temperature at which step (I) is performed is, for example, 20-80°C, and may be 40-60°C. The implementation time of step (I) varies depending on the composition of the solution system, but is, for example, 0.2 to 24 hours, and may be 0.5 to 4 hours. In step (I), aging of the formed wet gel may proceed as necessary. Aging can be performed, for example, by leaving the wet gel in an atmosphere at a temperature of about 20 to 120° C. for about 1 to 48 hours.

[Step (II)]
In step (II), the wet gel is dried to form a melamine resin-based framework from the framework phase of the wet gel, and macropores are formed from the solution phase of the wet gel to form the framework. and an organic porous body having macropores.

Drying can be performed, for example, by removing the first solvent from the wet gel. The removal of the first solvent may be performed at room temperature or in a heated atmosphere. The removal of the first solvent may be performed under normal pressure or under a reduced pressure atmosphere.

In step (II), the wet gel may be dried after replacing the solvent contained in the wet gel from the first solvent with the second solvent (solvent replacement). However, the second solvent preferably has a lower surface tension and/or dielectric constant than the first solvent. Values at temperatures in the range of 20-25° C. can be used for surface tension and dielectric constant. In an aspect in which the second solvent has a smaller surface tension and/or dielectric constant than the first solvent, the surface tension of the solution phase and/or the skeleton of the melamine resin (having polar groups such as amino groups and hydroxyl groups) and the solution It is possible to suppress the reduction of mesopores due to the shrinkage and deformation of the framework during drying, which can occur due to the interaction between phases. In other words, this aspect is advantageous for forming an organic porous material having a hierarchical porous structure. In addition, for example, the specific surface area and the total pore volume of the organic porous material can be maintained by the above suppression.

Examples of second solvents are alcohols such as isopropanol (IPA), alkanes such as n-hexane, ethers such as diethyl ether, hydrofluoroethers, hydrofluorocarbons.

The surface tension (20° C.) of the second solvent may be 19.0 mN/m or less. The surface tension of n-hexane (20° C.) is 18.4 mN/m. DMF as an example of the first solvent has a surface tension (20° C.) of 37.1 mN/m.

The dielectric constant (20° C.) of the second solvent may be 20 or less, 15 or less, 10 or less, or even 5 or less. Isopropanol has a dielectric constant (20° C.) of 18, and n-hexane (20° C.) has a dielectric constant of 2.0. Solvents with a dielectric constant of 10 or less at 20° C. can be classified as low-polar solvents, and solvents with a dielectric constant of 5 or less can be classified as non-polar solvents. The second solvent may be a low-polar solvent or a non-polar solvent. DMF, which is an example of the first solvent, has a dielectric constant (20° C.) of 37.

Drying may be performed by supercritical drying or freeze-drying. Supercritical drying using a supercritical fluid can more reliably suppress the reduction of mesopores. An example of a supercritical fluid is a _CO2 fluid.

In step (II), the wet gel may be dried after the liquid impregnation treatment is performed on the wet gel. When solvent replacement is performed in step (II), the liquid impregnation treatment may be performed before and/or after solvent replacement. According to the liquid impregnation treatment, depending on the conditions, for example, at least one selected from an increase in the pore diameter B of the mesopores, an increase in the specific surface area of the organic porous material, and an increase in the total pore volume of the organic porous material. one is possible. Further, according to the liquid impregnation treatment, the pore diameter B of the mesopores can be controlled independently of the pore diameter A of the macropores depending on the conditions. The pore diameter B of the mesopores can be controlled, for example, between 2 nm and 40 nm. According to the studies of the present inventors, there is a possibility that the dissolution of the skeleton (framework component) due to the liquid impregnation treatment is involved in the change in the pore size B. Moreover, it is presumed that the melamine resin dissolved by the liquid impregnation treatment is not reprecipitated. A melamine resin has high resistance to water and various solvents, and exhibits almost no swelling in water and various solvents. For this reason, it can be said that the above-mentioned effect of the liquid impregnation treatment is unexpected.

The liquid impregnation treatment can be performed, for example, by immersing the wet gel in a liquid at a predetermined temperature. The liquid may be heated. After solvent replacement with the liquid, the wet gel may be immersed. The predetermined temperature is, for example, 4 to 500.degree. C., and may be 4 to 230.degree. C. and 20 to 200.degree. The immersion time is, for example, 1 to 120 hours, and may be 5 to 72 hours. You may immerse under a normal pressure or pressurization. The pressurization pressure may be the vapor pressure of the liquid at the liquid impregnation temperature. Such pressures above atmospheric pressure can be achieved by immersion in a closed container.

An example of liquid impregnation treatment is hydrothermal treatment using heated water as the liquid. Hydrothermal treatment can achieve, for example, an increase in the pore diameter B of mesopores and an increase in the specific surface area and/or the total pore volume of the organic porous material. The water used for the hydrothermal treatment may or may not substantially contain at least one selected from acids, bases and salts. The water may or may not be substantially free of acids and/or bases. The water may be pure water such as ion-exchanged water or distilled water, or may be high-purity or ultra-high-purity water obtained by passing through a reverse osmosis membrane, an ultrafiltration membrane, or a microfiltration membrane. . The temperature of the hydrothermal treatment is, for example, 90-500°C, and may be 100-400°C.

Another example of a liquid impregnation treatment is an acid treatment using an acidic solution on the liquid and a base treatment using a basic solution on the liquid. The solution used for acid treatment usually contains acid. The solution used for base treatment usually contains a base.

The acid treatment can increase the specific surface area and/or the total pore volume of the organic porous material. In addition, the pore size B of the mesopores can be increased by changing the type of acid and the temperature of the acid treatment. Examples of acids are inorganic acids such as hydrochloric acid, nitric acid and nitric acid, and organic acids such as TFA and trifluoromethanesulfonic acid. Depending on the type of acid, a solution with a concentration of about 0.001 to 5 mol/L can be used for acid treatment. Examples of solvents for solutions used for acid treatment are water and alcohols such as IPA. For example, in a hydrochloric acid aqueous solution with a concentration of 0.1 mol/L (hereinafter, the hydrochloric acid aqueous solution is simply referred to as "hydrochloric acid"), the pore diameter B of the mesopores can be increased by setting the acid treatment temperature to 120° C. or higher. In TFA (aqueous solution or IPA solution) with a concentration of 0.0046 mol/L, the pore size B of mesopores can be increased by heat treatment at 100° C. or higher.

The base treatment can increase the specific surface area and/or the total pore volume of the organic porous material. According to the studies of the present inventors, the pore size B tends to be maintained in the base treatment. Examples of bases are alkylammonium hydroxides such as tetramethylammonium hydride, sodium hydroxide and ammonia. Depending on the type of base, a solution with a concentration of about 0.001 to 5 mol/L can be used for base treatment. Examples of solvents for solutions used for base treatment are water and alcohols such as IPA.

The temperature of acid treatment and base treatment is, for example, 10 to 300°C, and may be 20 to 150°C. The immersion time when acid treatment or base treatment is performed by immersion is, for example, 0.5 to 72 hours, and may be 1 to 24 hours.

Yet another example of a liquid impregnation treatment is an alcohol treatment using heated alcohol for the liquid. An example of alcohol is IPA. Alcohol may contain water. The alcohol treatment can increase the specific surface area and/or the total pore volume of the organic porous material. Moreover, the pore diameter B of the mesopores can be increased by changing the type and temperature of the solution used for the treatment. The alcohol treatment solution may or may not be substantially acid and/or base free.

The temperature of alcohol treatment is, for example, 10 to 300°C, and may be 20 to 120°C. The immersion time when the alcohol treatment is performed by immersion is, for example, 0.5 to 72 hours, and may be 1 to 24 hours.

In the liquid impregnation treatment, two or more treatments selected from hydrothermal treatment, acid treatment, base treatment and alcohol treatment may be combined.

When obtaining an organic porous body having macropores and mesopores, and when obtaining an organic porous body having a hierarchical porous structure of macropores and mesopores, in step (II), the wet gel After performing a treatment (adjustment treatment) for adjusting the diameter of the pores (original mesopores), the wet gel may be dried. Adjustment of the pore size is, for example, an increase in the pore size. Process (II
), the conditioning process may be performed before and/or after the solvent replacement. An example of a conditioning treatment is the liquid impregnation treatment described above.

The production method of the present invention may include steps other than steps (I) and (II) as long as an organic porous body having a melamine resin-based skeleton and macropores is obtained.

Another example of the process is a post-treatment process for the organic porous material obtained through the process (II). An example of the post-treatment step is acid treatment of the organic porous body. The acid treatment can increase the specific surface area and/or the total pore volume of the organic porous material. In addition, the pore size B of the mesopores can be increased by changing the type of acid and the temperature of the acid treatment. The acid treatment of the organic porous body can be carried out, for example, in the same manner as the acid treatment of the wet gel described above.

The organic porous material obtained by the production method of the present invention can be used for various uses described below. A high degree of freedom in pore design is advantageous for use in various applications.

The organic porous material obtained by the production method of the present invention can exhibit high water resistance, acid resistance and base resistance, especially base resistance, based on the melamine resin. High base resistance can be an advantage over, for example, silica-based porous bodies, which are considered to be inferior in base resistance. In addition, the organic porous material obtained by the production method of the present invention can exhibit low swelling or shrinkage in water and various solvents.

According to the production method of the present invention, for example, the organic porous body A described below can be produced. However, the organic porous body manufactured by the manufacturing method of the present invention is not limited to the organic porous body A.

[Organic porous body A]
The organic porous material A has a skeleton made of a melamine resin, macropores, and mesopores having openings on the surface of the skeleton. Macropores are the voids between the skeleton. The skeleton constitutes the walls of the macropores. Mesopores constitute a hierarchical porous structure together with macropores. The pore diameter A of the macropores is 0.1 μm or more and 10 μm or less. The pore diameter B of the mesopores is 2 nm or more and 40 nm or less. As described above, both pore diameter A and pore diameter B are modes (mode values). The modes determined by the pore size distribution measurement can be defined as the pore size A and the pore size B.

The ratio A/B of the pore diameter A of the macropores to the pore diameter B of the mesopores may be 15 or more, 50 or more, 100 or more, 150 or more, 300 or more, 500 or more, or even 1000 or more. . An organic porous material having a ratio A/B of 300 or more can be used, for example, as a carrier for adsorption, separation or reaction for treating low-molecular-weight molecules, or as a support with an aperture diameter of several μm or more. It can be preferably used for applications as a filter having. Organic-based porous bodies with a ratio A/B of 100 or less can be used, for example, as supports for adsorption, separation or reaction processing of medium to large molecules or with openings of 1 μm or less, which are made possible by pore sizes B greater than 10 nm. It can be preferably used as a filter having a caliber. In addition, in this specification, the carrier for adsorption is also described as "adsorbent".

The average skeleton diameter of the organic porous material A is, for example, 0.1 μm or more and 50 μm or less, and may be 0.1 μm or more and 10 μm or less, or further 0.5 μm or more and 5 μm or less. The skeleton diameter is the diameter of a cross section perpendicular to the direction in which the skeleton extends. The average skeleton diameter can be determined, for example, by observing an organic porous material using a magnifying observation technique such as an electron microscope. At least 10 evaluation points can be assigned to arbitrary locations of the skeleton, and the average value of the skeleton diameters evaluated at each point can be taken as the average skeleton diameter.

The melamine resin, which is the base material of the skeleton, has a structure formed by condensation polymerization of melamine monomers, aldehyde monomers, and/or the above oligomers.

The organic porous material A has a hierarchical porous structure of macropores and mesopores. This is advantageous, for example, for separation and/or reaction carrier, adsorbent, and catalyst support applications.

The organic porous body A may have a co-continuous structure of skeleton and macropores. The organic porous material A having a co-continuous structure is advantageous for use as, for example, a carrier for separation and/or reaction, an adsorbent, and a catalyst support.

The macropores of the organic porous material A may be evaluated by pore size distribution measurement of the organic porous material A and may exhibit a pore size distribution of 20 μm or less. The pore size distribution may be 10 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, or even 4 μm or less. The pore size distribution is the maximum and minimum values obtained based on the baseline in the pore distribution curve (typically, differential pore volume distribution or Log differential pore volume distribution) obtained by pore distribution measurement. It can be obtained as a difference (see Figure 1). The organic porous material A having macropores with a narrow pore size distribution is advantageous for use as, for example, a carrier for separation and/or reaction and an adsorbent.

The organic porous material A can have a large specific surface area. The specific surface area is, for example, 10 m ² /g or more, 50 m ² /g or more, 100 m ² /g or more, 120 m ² /g or more, 200 m ² /g or more, 250 m ² /g or more, 300 m 2 /g or more, 350 ^{m 2} /g or more. ² /g or more, and may be 400 m ² /g or more. The upper limit of the specific surface area is, for example, 1000 m ² /g or less. The organic porous material A having a large specific surface area is advantageous for use as, for example, a carrier for separation and/or reaction, an adsorbent, and a catalyst carrier.

The organic porous body A can have a large total pore volume. The total pore volume is, for example, 0.10 cm ³ /g or more, 0.20 cm ³ /g or more, 0.40 cm ³ /g or more, 0.50 cm ³ /g or more, 0.60 cm ³ /g or more, 1 0 cm ³ /g or more, 1.5 cm ³ /g or more, or even 2.0 cm ³ /g or more. The upper limit of the total pore volume is, for example, 3.5 cm ³ /g or less. The organic porous material A having a large total pore volume is advantageous for applications such as carriers for separation and/or reactions, adsorbents, and supports for catalysts.

The specific surface area and total pore volume of the organic porous material A can be evaluated by pore distribution measurement. For evaluation of specific surface area and total pore volume, for example, the Barrett-Joyner-Halenda (BJH) method can be used.

The skeleton of the organic porous material A is based on a melamine resin. Therefore, the organic porous body A can exhibit excellent water resistance, acid resistance and base resistance, particularly base resistance. This allows, for example, the macropore configuration to be maintained even when in contact with water, acids or bases. In addition, the organic porous material A can exhibit low swelling or shrinking properties with respect to water and various organic solvents. The organic porous body A can, for example, suppress changes in volume due to various organic solvents. This property is advantageous, for example, for separation and/or reaction support, adsorbent, and catalyst support applications. Moreover, this characteristic is particularly advantageous in an organic porous column containing the organic porous body A in a housing.

The organic porous body A can have various shapes. Examples of shapes are particles, sheets and bulks such as cuboids, discs and cylinders. The organic porous body A may be a monolithic body such as a sheet or bulk. The organic porous body A, which is a monolithic body, is easy to handle and can improve the uniformity of properties compared to a porous body obtained by, for example, aggregating and molding particles. The pore diameter B of the mesopores of the organic porous material A is in the range of 2 nm or more and 40 nm or less. Therefore, the strength of the monolith body can be ensured more reliably.

The organic porous body A can be produced, for example, by the production method of the present invention described above.

[Organic porous body B]
The organic porous body B is an organic porous body obtained by the production method of the present invention described above. The organic porous body B may have the configuration and/or one or more properties of the porous body A described above in the description of the organic porous body A.

[Applications of Organic Porous Materials A and B]
The organic porous bodies A and B can be used for various purposes. Examples of applications are supports for separations and/or reactions, adsorbents, supports for catalysts, and abrasives. The article for each of the above uses, such as an adsorbent, contains the organic porous body A and/or the organic porous body B. Adsorbents may be adsorbents such as organic compounds, inorganic compounds, metals, peptides, proteins, nucleic acids, viruses, cells, microsomes, colloids, and the like. The adsorbent can be an adsorbent capable of recovering metals with an acid, or an adsorbent capable of adsorbing metals on the order of ppb. Carriers for separation may be carriers that separate organic compounds, inorganic compounds, metals, peptides, proteins, nucleic acids, viruses, cells, microsomes, colloids, and the like. The catalyst may be a cell catalyst. The organic porous bodies A and B may be fired to form a carbon porous body. The carbon porous material can be used as a raw material for N-doped carbon and carbon porous material. N-doped carbon can be used, for example, in semiconductors. However, the applications of the organic porous bodies A and B are not limited to the above examples.

An organic porous column may be obtained from the organic porous bodies A and B. The organic porous column comprises an organic porous body A and/or an organic porous body B and a housing. The organic porous body A and/or the organic porous body B are housed in a housing. Examples of organic porous columns are adsorption columns, separation columns and reaction columns. The adsorption column may be an adsorption column for organic compounds, inorganic compounds, metals, peptides, proteins, nucleic acids, viruses, cells, microsomes, colloids, and the like. The separation column may be a separation column for organic compounds, inorganic compounds, metals, peptides, proteins, nucleic acids, viruses, cells, microsomes, colloids, and the like.

Even in an inorganic porous column containing a silica-based porous material, it is possible to adsorb metals and separate peptides by introducing functional groups onto the surface thereof. However, silica is weak against bases and easily dissolved in basic solutions. In addition, elution due to hydrolysis proceeds gradually with respect to solutions in which hydroxyl groups are present (for example, water, alcohol, etc.). The functional groups introduced on the surface of silica are easily eluted by acid. The same applies to inorganic oxides other than silica.

Existing organic porous materials (eg, styrene beads) are usually swelled or shrunk by an organic solvent to change their volume. A change in volume of a porous body, for example, becomes a big problem when used as a porous column. Swelling can, for example, clog channels in a column. Shrinkage can, for example, cause the column to lose function. There are also organic porous materials (styrene-divinylbenzene system, etc.) that are difficult to swell in organic solvents. However, the porous material requires a post-process to directly introduce a functional group into the styrene skeleton.

On the other hand, the organic porous bodies A and B can exhibit excellent water resistance, acid resistance and base resistance, and low swelling and shrinkage properties with respect to water and various organic solvents. In the organic porous bodies A and B, for example, changes in volume due to various organic solvents can be suppressed. In addition, the organic porous bodies A and B can suppress shrinkage due to drying, for example, and can be used in a state other than a wet state. Furthermore, the organic porous bodies A and B have countless polar groups such as amino groups derived from the melamine resin without performing post-processing. These points are advantageous for use in each of the applications described above.

EXAMPLES The present invention will be described in more detail below with reference to examples. The present invention is not limited to the specific embodiments shown below.

[Preparation of materials]
PEO: manufactured by Sigma-Aldrich, number average molecular weight (Mn) 100,000 or 200,000 Methylolmelamine: manufactured by Nippon Carbide Industry, Nikaresin (registered trademark)

[Evaluation method for organic porous material]
The produced organic porous bodies were evaluated as follows.

<Structure of Skeleton and Macropores>
The structure of the skeleton and macropores was observed with a scanning electron microscope (hereinafter referred to as "SEM"). JSM-IT500HR manufactured by JEOL was used as the SEM.

<Pore diameter and pore distribution of macropores>
The pore size and pore size distribution of the macropores were evaluated by a mercury intrusion measurement device (manufactured by Shimadzu Corporation, Autopore-IV-9505). The evaluation was carried out after drying the organic porous material in a vacuum (120° C., 4 hours or more).

<Mesopore diameter, adsorption/desorption isotherm and pore distribution, specific surface area and total pore volume>
The pore diameter B of the mesopores, the adsorption/desorption isotherm and pore distribution, and the specific surface area and total pore volume of the organic porous material were evaluated by a nitrogen adsorption analyzer (BELSORP-mini manufactured by Microtrack Bell). The BJH method was adopted for the evaluation. The evaluation was carried out after drying the organic porous material in a vacuum (120° C., 4 hours or more).

[1. Control of macropores]
<Preparation of organic porous material>
X mg of PEO was dissolved in 3.0 mL of DMF at 80°C. The solution was returned to room temperature, and 0.35 g of methylolmelamine (average molecular weight: 260) was further dissolved. Next, 50 μL of an aqueous nitric acid solution (concentration: 60% by weight) was added as a polymerization catalyst, stirred, and allowed to stand at 40° C. to promote gelation. Subsequently, aging was performed at 40° C. for 12 hours and at 60° C. for 3 hours to prepare a wet gel. The wet gel was then solvent-exchanged with isopropanol (IPA) and then with n-hexane (HEX). Next, the wet gel was placed in an empty container having an internal volume of 100 mL, and dried under normal pressure without covering the container to obtain an organic porous material. Solvent replacement was carried out by repeating 8-hour immersion in 50 mL of each solvent twice. The drying temperature of normal pressure drying was 40° C., and the drying time was 24 hours.

Table 1 shows the Mn and amount X of PEO in each sample.

FIG. 2A shows SEM observations of the skeleton and macropores for samples 1A-1F. FIG. 3 shows SEM observations of the skeleton and macropores for Samples 2A-2E. Tables 2 and 3 also show the macropore diameter A and the mesopore diameter B of samples 1A to 1F and 2A to 2E, respectively. "-" in Tables 2 and 3 means unmeasured.

As shown in FIGS. 2A and 3 and Tables 2 and 3, the pore diameter A of the macropores of the organic porous material could be controlled independently of the pore diameter B of the mesopores by the Mn and the amount of PEO added. The pore size A tended to increase as the Mn of PEO increased. In samples 1A to 1E in which Mn of PEO is 200,000, the pore diameter A could be controlled within the range of 1.0 to 10 μm. In samples 2A to 2E, in which Mn of PEO is 100,000, the pore size A could be controlled within the range of 0.1 to 1.0 μm.

Also, samples 1B to 1F and 2B to 2E had a co-continuous structure of skeleton and macropores. In samples 1A and 2A, the pore size A of the macropores was small, and the macropores could not be confirmed in the SEM image.

According to pore distribution measurement and SEM observation, samples 1A-1F and 2A-2E had a hierarchical porous structure of macropores and mesopores. As a representative example, the results of SEM observation of the framework and macropores of Sample 1C, and mesopores having openings on the surface of the framework are shown in FIG. 2B.

4 and 5 show the results of pore distribution measurement of macropores for samples 1D and 1E (cumulative pore volume in FIG. 4 and differential pore volume distribution in FIG. 5). As shown in FIGS. 4 and 5, the pore size distribution of the macropores was 2.2 μm for sample 1D and 3.7 μm for sample 1E, less than 8 μm. The same was true for samples 1A-1C, 1F and 2A-2E.

The nitrogen adsorption and desorption isotherms of samples 1C-1E, 2A and 2C are shown in FIG. FIG. 7 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for samples 1C to 1E, 2A, and 2C. As shown in FIGS. 6 and 7, even when the pore diameter A of the macropores changed, the pore diameter B of the mesopores hardly changed. The same was true for samples 1A, 1B, 1F, 2B, 2D and 2E.

[2. Control of mesopores]
(I) Selection of solvent used for solvent replacement Sample 2CA was obtained in the same manner as sample 2C except that only IPA was used for solvent replacement and the drying temperature was changed to 60°C. FIG. 8 shows nitrogen adsorption and desorption isotherms of samples 2C and 2CA. FIG. 9 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for samples 2C and 2CA. Table 4 shows the specific surface areas and total pore volumes of Samples 2C and 2CA.

As shown in FIGS. 8, 9 and Table 4, by drying at normal pressure with the solvent replaced with HEX (Sample 2C), compared to the case of drying at normal pressure with the solvent replaced with IPA (Sample 2CA), The specific surface area and total pore volume of the organic porous material increased. In addition, the pore size B of the mesopores was larger when the solvent was replaced with HEX and dried under normal pressure. The change in specific surface area and total pore volume was considered to be due to the difference in how much the original mesopores of the wet gel remained after drying (residual ratio). Moreover, it was considered that the change in the pore diameter B was due to the difference in shrinkage force that the original mesopores of the wet gel received during drying. Differences in retention rate and shrinkage force were presumed to be due to differences in surface tension and/or polar strength between IPA and HEX. The selection of the solvent used for solvent replacement had little effect on the shape and pore size A of the macropores.

(II) Drying Conditions Samples 3A to 3C were obtained in the same manner as Sample 1A, except that 45 mg of Mn 200,000 PEO was used. However, only IPA was used for solvent replacement of sample 3A. Drying of sample 3C was performed by supercritical drying using CO ₂ in a supercritical state (pressure 14 MPa, temperature 80° C.) without replacing the solvent. Samples 3AL and 3BL were obtained in the same manner as Samples 3A and 3B, except that the drying time was changed to 48 hours. Samples 3AL and 3BL were obtained by drying for a longer period of time than samples 3A and 3B, in other words, by drying under conditions in which the solvent evaporates from the closed space at a moderate rate.

FIG. 10 shows nitrogen adsorption and desorption isotherms of samples 3A, 3AL, 3B, 3BL and 3C. FIG. 11 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for Samples 3A, 3AL, 3B, 3BL, and 3C. Table 5 shows the specific surface areas and total pore volumes of Samples 3A, 3AL, 3B, 3BL and 3C.

As shown in FIGS. 10 and 11 and Table 5, the specific surface area and the total pore volume of the organic porous material increased by lengthening the normal pressure drying time. On the other hand, the pore diameter B of the mesopores hardly changed. Moreover, the supercritical drying significantly increased the specific surface area and the total pore volume of the organic porous material, and also increased the pore size B of the mesopores. The change in specific surface area and total pore volume was considered to be due to the difference in the residual ratio of original mesopores. Also, the increase in the pore diameter B due to supercritical drying was considered to be due to the decrease in the aforementioned shrinkage rate with respect to the original mesopores. It should be noted that the drying time and drying method had little effect on the shape and pore size A of the macropores.

(III) Hydrothermal treatment Samples 4A to 4E were obtained in the same manner as Sample 1C, except that the wet gel was hydrothermally treated. Hydrothermal treatment was performed between aging and solvent replacement. In the hydrothermal treatment, the wet gel after aging is repeatedly immersed in distilled water at room temperature (25 ° C.) for 8 hours, and then the wet gel is immersed in about 20 mL of distilled water in a sealed container. It was carried out by heating at T° C. for 24 hours. FIG. 12 shows nitrogen adsorption and desorption isotherms of samples 1C and 4A to 4E. FIG. 13 shows the results of mesopore distribution measurement (differential pore volume distribution) for samples 1C and 4A to 4E. Table 6 shows the hydrothermal treatment temperature T (except sample 1C), mesopore diameter B, specific surface area and total pore volume of samples 1C and 4A to 4E.

As shown in FIGS. 12 and 13 and Table 6, increasing the temperature of the hydrothermal treatment increased the pore diameter B of the mesopores and increased the specific surface area and total pore volume of the organic porous material. The specific surface area and total pore volume were maximized when the hydrothermal treatment temperature was 120°C. When the hydrothermal treatment time was varied, the longer the time, the larger the pore size B of the mesopores, and the specific surface area and total pore volume tended to increase. The hydrothermal treatment had little effect on the macropore shape and pore diameter A.

Sample 4F was obtained in the same manner as Sample 1A, except that 45 mg of PEO with Mn of 200,000 was used. In addition, samples 4G to 4M (hydrothermal treatment temperature 90° C.) and samples 4N to 4R (hydrothermal treatment temperature 120° C.) were obtained in the same manner as sample 4F except that the wet gel was subjected to hydrothermal treatment. Hydrothermal treatment was performed after solvent replacement with IPA. In the hydrothermal treatment, the wet gel after solvent replacement with IPA is repeatedly immersed in distilled water at room temperature for 8 hours, and then the wet gel is immersed in about 20 mL of distilled water in a sealed container. C. or 120.degree. C. for D days (90.degree. C.) or L hours (120.degree. C.). In addition, each sample except for sample 4F was obtained by exchanging the solvent with IPA and HEX for the wet gel after the hydrothermal treatment and then drying at normal pressure. The nitrogen adsorption and desorption isotherms of samples 4F-4M and samples 4F, 4N-4R are shown in FIGS. 14 and 16, respectively. The results of mesopore pore distribution measurement (differential pore volume distribution) for samples 4F to 4M and samples 4F and 4N to 4R are shown in FIGS. 15 and 17, respectively. Table 7 shows the temperature and time D of the hydrothermal treatment of Samples 4F, 4G to 4R (except Sample 4F), as well as the specific surface area and total pore volume.

As shown in FIGS. 14 to 17 and Table 7, by increasing the time and/or temperature of the hydrothermal treatment after solvent replacement, the pore diameter B of the mesopores increases and the specific surface area of the organic porous material and increased total pore volume. The specific surface area and total pore volume became the largest when the hydrothermal treatment time was 5 days (90°C) and 12 hours (120°C). The hydrothermal treatment had little effect on the macropore shape and pore diameter A.

Samples 4S to 4Z and 4α and 4β were obtained in the same manner as Sample 4F, except that the wet gel was subjected to hydrothermal treatment. Hydrothermal treatment was performed after solvent replacement with IPA. In the hydrothermal treatment, the wet gel after solvent replacement with IPA is repeatedly immersed in distilled water at room temperature for 8 hours, and then the wet gel is immersed in about 20 mL of distilled water in a sealed container. C. for 24 hours. Each sample was obtained by subjecting the wet gel after hydrothermal treatment to solvent replacement with IPA and HEX, followed by normal pressure drying. FIG. 18 shows nitrogen adsorption and desorption isotherms of samples 4F, 4S to 4β. FIG. 19 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for samples 4F and 4S to 4β. Table 8 shows the hydrothermal treatment temperature T (excluding sample 4F), specific surface area and total pore volume of samples 4F and 4S to 4β.

As shown in FIGS. 18, 19 and Table 8, by increasing the temperature of the hydrothermal treatment after solvent replacement, the pore diameter B of the mesopores increases, and the specific surface area and total pore volume of the organic porous material increase. Increased. When the hydrothermal treatment temperature T was 130°C, the specific surface area and the total pore volume were the largest. When the hydrothermal treatment temperature was 140°C or higher, the pore size B of the mesopores tended to decrease, and the specific surface area and total pore volume also tended to decrease, compared to those at 130°C. The hydrothermal treatment had little effect on the macropore shape and pore diameter A.

(IV) Liquid impregnation treatment using various liquids 45 mg of Mn 200,000 PEO was used, and the wet gel after aging was subjected to liquid impregnation treatment using various liquids in the same manner as sample 1A. , to obtain samples 5A-5D. Liquid impregnation was performed after solvent replacement with IPA. The liquid impregnation treatment was carried out by immersing the wet gel after solvent replacement with IPA in about 20 mL of the above liquid in a sealed container and heating at a temperature of 120° C. for 24 hours. Samples 5A to 5D were obtained by performing solvent replacement with IPA and HEX on the wet gel after the liquid impregnation treatment and then drying at normal pressure. The nitrogen adsorption and desorption isotherms of Samples 5A-5D are shown in FIG. FIG. 21 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for samples 5A to 5D. Table 9 shows the liquid, specific surface area and total pore volume used in the liquid impregnation treatment of Samples 5A-5D.

As shown in FIGS. 20, 21 and Table 9, the pore diameter B of the mesopores increased and the specific surface area and total pore volume of the organic porous material increased in the liquid impregnation treatment at 120° C. using any of the liquids. Increased. Although not shown, when the liquid impregnation time was changed, the longer the time, the larger the pore diameter B of the mesopores, and the specific surface area and total pore volume tended to increase. It should be noted that the liquid impregnation treatment had little effect on the shape and pore size A of the macropores.

(V) Acid Treatment and Base Treatment Samples 6A to 6C were obtained in the same manner as Sample 4F, except that the wet gel was acid treated with hydrochloric acid. Acid treatment was performed after solvent replacement with IPA. The acid treatment is performed by repeatedly immersing the wet gel after solvent replacement with IPA in hydrochloric acid (concentration 0.1 mol/L) at room temperature for 8 hours, followed by immersing it in about 20 mL of the above hydrochloric acid at a temperature of T ° C. for 24 hours. It was performed by soaking the wet gel. Each sample was obtained by exchanging the solvent with IPA and HEX for the wet gel after the acid treatment and then drying it under normal pressure. FIG. 22 shows nitrogen adsorption and desorption isotherms of samples 4F and 6A to 6C. FIG. 23 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for samples 4F and 6A to 6C. Table 10 shows the acid treatment temperature T (except sample 4F), specific surface area and total pore volume of samples 4F and 6A to 6C.

As shown in FIGS. 22 and 23 and Table 10, the acid treatment at 100° C. or higher increased the specific surface area and total pore volume of the organic porous material. The pore diameter B of the mesopores hardly changed in the acid treatment under each of the above conditions. The acid treatment had little effect on the macropore shape and pore diameter A. In addition, in the acid treatment at 60°C or less, the skeleton components did not dissolve, and the recombination of the skeleton was promoted by the hydrolysis and polycondensation reaction catalyzed by the acid, resulting in a decrease in the specific surface area and total pore volume. It is estimated to be.

Samples 6D to 6G were obtained in the same manner as sample 4F, except that the wet gel was acid-treated with TFA. Acid treatment was performed after solvent replacement with IPA. The acid treatment was performed by immersing the wet gel after solvent replacement with IPA in an IPA solution of TFA (concentration 4.6 mmol/L, temperature 25° C., about 20 mL) at a temperature T° C. for 24 hours. Each sample was obtained by exchanging the solvent with IPA and HEX for the wet gel after the acid treatment and then drying it under normal pressure. FIG. 24 shows nitrogen adsorption and desorption isotherms of samples 4F and 6D to 6G. FIG. 25 shows the results of mesopore pore distribution measurement (differential pore volume distribution) for samples 4F and 6D to 6G. Table 11 shows the acid treatment temperature T (except sample 4F), specific surface area and total pore volume of samples 4F and 6D to 6G.

As shown in FIGS. 24 and 25 and Table 11, acid treatment at 100° C. or higher increased the pore diameter B of mesopores, and also increased the specific surface area and total pore volume of the organic porous material. Moreover, the pore diameter B, the specific surface area and the total pore volume tended to increase as the acid treatment temperature increased. The acid treatment had little effect on the macropore shape and pore diameter A. In addition, in the acid treatment at 60°C or less, the skeleton components did not dissolve, and the recombination of the skeleton was promoted by the hydrolysis and polycondensation reaction catalyzed by the acid, resulting in a decrease in the specific surface area and total pore volume. It is estimated to be.

Samples 6H to 6J were obtained in the same manner as Sample 4F, except that the wet gel was subjected to base treatment with aqueous ammonia. Base treatment was performed after solvent replacement with IPA. The base treatment was performed by immersing the wet gel after solvent replacement with IPA in an aqueous ammonia solution (concentration: 2 mol/L, temperature: 25°C, about 20 mL) at a temperature of T°C for D days. Each sample was obtained by performing solvent substitution with IPA and HEX on the wet gel after base treatment and then drying under normal pressure. FIG. 26 shows nitrogen adsorption and desorption isotherms of samples 4F and 6H to 6J. FIG. 27 shows the mesopore distribution measurement results (differential pore volume distribution) of samples 4F and 6H to 6J. Table 12 shows the temperature T and time D of the base treatment of Samples 4F, 6H to 6J (except Sample 4F), as well as the specific surface area and total pore volume.

As shown in FIGS. 26 and 27 and Table 12, the base treatment at 80° C. or higher increased the specific surface area and total pore volume of the organic porous material. The pore diameter B of the mesopores hardly changed by the base treatment under the above conditions. Also, the higher the temperature and/or the longer the time of the base treatment, the higher the specific surface area and total pore volume tended to increase. The base treatment had little effect on the macropore shape and pore diameter A. In addition, in the base treatment at 60°C or less, the skeleton components did not dissolve, and the recombination of the skeleton was promoted by the hydrolysis and polycondensation reaction catalyzed by the base, resulting in a decrease in the specific surface area and total pore volume. It is estimated to be.

Samples 6K and 6L were obtained in the same manner as Sample 1D except that the wet gel was acid-treated with hydrochloric acid or base-treated with sodium hydroxide. Acid treatment of sample 6K and base treatment of sample 6L were performed after solvent replacement with IPA. For the acid treatment of sample 6K and the base treatment of sample 6L, respectively, the wet gel after solvent replacement with IPA was treated with hydrochloric acid (concentration 0.1 mol/L, about 20 mL) or aqueous sodium hydroxide solution (concentration 1 mol/L, about 20 mL) at room temperature. 20 mL) at 25° C. for 12 hours. Samples 6K and 6L were each obtained by subjecting the wet gel after acid treatment or base treatment to solvent replacement with HEX and subsequent normal pressure drying. Separately from the above, sample 1D was post-processed with acid treatment with hydrochloric acid or base treatment with sodium hydroxide to obtain samples 6M and 6N. Acid treatment of sample 6M and base treatment of sample 6N were carried out in the same manner as acid treatment of sample 6K and base treatment of sample 6L, respectively. Samples 6M and 6N were each obtained by subjecting the organic porous material after acid treatment or base treatment to solvent replacement with HEX and subsequent normal pressure drying. Nitrogen adsorption and desorption isotherms of samples 1D, 6K to 6N are shown in FIG. FIG. 29 shows the mesopore distribution measurement results (differential pore volume distribution) for samples 1D and 6K to 6N. Table 13 shows the specific surface area and total pore volume of each sample, including samples 1D and 6K-6N.

As shown in FIGS. 28 and 29 and Table 13, the acid treatment under the above conditions increased the specific surface area and total pore volume of the organic porous material. In particular, the amount of increase in sample 6M was large. On the other hand, the specific surface area and total pore volume of the organic porous material were slightly reduced by the base treatment under the above conditions. The pore diameter B of the mesopores hardly changed in the acid treatment and base treatment under the above conditions. The acid treatment and base treatment hardly affected the shape and diameter A of the macropores. It is presumed that in the acid treatment of the organic porous material, the skeleton component was dissolved by the hydrolysis reaction catalyzed by the acid, and the specific surface area and the total pore volume increased. On the other hand, it is presumed that the base treatment of the organic porous material did not progress the dissolution of the skeleton component and slightly decreased the specific surface area and the total pore volume. Regarding the acid treatment of the wet gel, the sample 1D series showed an increase in specific surface area and total pore volume at lower treatment temperatures compared to the sample 4F series described above. It is presumed that this is because the sample 1D series has a denser skeleton, and the dissolution of the skeleton component by acid is relatively large when viewed per unit volume.

[3. Effect of water on solution system]
Samples 7A-7D were obtained in the same manner as Sample 1C, except that VμL of water was added to the solution system forming the wet gel. Distilled water was used as the water to be added. FIG. 30 shows the nitrogen adsorption and desorption isotherms of each sample. FIG. 31 shows the results of mesopore distribution measurement (differential pore volume distribution) for each sample. Table 14 shows the added amount V of water, the specific surface area and the total pore volume of each sample.

As shown in FIGS. 30, 31 and Table 14, the specific surface area and total pore volume of the organic porous material tended to decrease as the amount of water added to the solution system increased. On the other hand, the pore diameter B of the mesopores hardly changed. In addition, as the amount of water added to the solution system increased, the pore size A of the macropores decreased. It was presumed that water added to the solution system has the effect of suppressing phase separation between the skeleton phase and the solution phase.

[4. Usage examples for various applications]
(Preparation of column)
Sample 40 was pulverized in a mortar and classified in the particle size range of 20/63 μm using a wire mesh sieve having openings according to Japanese Industrial Standards (JIS) Z8801. The classified porous material was packed in a resin column (inner diameter: 5.5 mm) with an adsorbent height of 10 mm to prepare an organic porous column C1.

The two-stage pore silica gel disclosed in JP-A-2016-70937 was classified in the particle size range of 20/63 μm using the wire mesh sieve. Next, the classified silica gel was put into a toluene solution (10% by volume) of 2-aminoethyl-3-aminopropyltriethoxysilane (manufactured by Merck Millipore) and refluxed at 100° C. for 3 hours. Next, the temperature was returned to normal temperature, the silica gel was collected by filtration, washed with 2-propanol, and dried to obtain ethylenediamine silica gel into which ethylenediamine groups were introduced. The amount of ethylenediamine groups introduced was 250 μmol/mL gel per gel volume. Next, a silica column C2 was produced by packing ethylenediamine silica gel into a resin column (inner diameter: 5.5 mm) with an adsorbent height of 10 mm.

(Palladium dynamic adsorption and adsorption amount measurement)
42.4 mg of palladium acetate was dissolved in 2 mL of hydrochloric acid methanol solution (concentration 3.5% by weight) and diluted with water to a volume of 200 mL to obtain solution A containing palladium with a concentration of 100 ppm (by weight). Next, solution A was passed through each of columns C1 and C2 at a flow rate of 1 mL/min, and 5 mL of the solution was recovered from the outlet of each column. From each collected solution, the concentration of palladium on the outlet side of each column was calculated by the potassium iodide titration method. FIG. 32 shows the relationship (breakthrough curve) between the palladium concentration and the total amount of solution discharged from the outlet of each column. As shown in Figure 32, columns C1 and C2 showed comparable adsorption performance for palladium.

In column C1, palladium began to elute (breakthrough) when 50 mL of solution A was flowed. The dynamic adsorption amount of palladium at the time of breakthrough was 5 mg. The gel volume of column C1 is 0.238 mL. The dynamic adsorption amount of palladium per gel volume was 21 mg/mLgel (=200 μmol/mLgel).

In column C2, palladium began to elute when 45 mL of solution A was run. The dynamic adsorption amount of palladium at the time of breakthrough was 4.5 mg. The gel volume of column C2 is 0.238 mL. The dynamic adsorption amount of palladium per gel volume was 19 mg/mLgel (=180 μmol/mLgel). Here, the amount of ethylenediamine groups introduced into the silica gel of column C2 is 240 μmol/mLgel. That is, breakthrough was confirmed when palladium was adsorbed by 75% of the introduced amount of ethylenediamine groups.

The palladium adsorption capacities of columns C1 and C2 are comparable as shown in FIG. Therefore, the amount of palladium ion-exchange groups (amino groups and hydroxyl groups) that act effectively in the organic porous material packed in column C1 was considered to be equivalent to the amount of ethylenediamine groups introduced in the silica gel of column C2. From the above results, the amount of palladium ion-exchange groups in the porous material was estimated to be 250 μmol/mLgel or more.

(Measurement of selective adsorption and desorption of metal ions)
As a solution B containing a plurality of metal ions, 1 mL of a general-purpose mixed standard solution XSTC-7, manufactured by US SPEX, diluted with ultrapure water was prepared. XSTC-7 contains metal ions of Au, Ir, Pd, Pt, Rh, Ru, Sn, Te, Hf and Sb at a concentration of 10 mg/L. XSTC-7 also contains 10% by weight hydrochloric acid and 1% by weight nitric acid. As the ultrapure water, water passed through a microfiltration membrane was used. In addition, XSTC-7 was diluted 10-fold with ultrapure water.

Next, solution B was passed through each of columns C1 and C2 at a flow rate of 1 mL/min, and the entire amount was recovered from the outlet of each column (column C1: recovered liquid RE1, column C2: recovered liquid RE2).

Next, for each of columns C1 and C2, an aqueous solution containing nitric acid with a concentration of 1 mol/L, hydrochloric acid with a concentration of 1 mol/L, and thiourea (with a concentration of 0.1 mol/L) and hydrochloric acid (with a concentration of 1 mol/L) was continuously flowed in this order at a flow rate of 1 mL/min, and the entire amount was recovered from the outlet of each column (Column C1: recovery liquid RE3 (nitric acid), RE4 (hydrochloric acid), RE5 (thiourea + hydrochloric acid ), column C2: recovery liquid RE6 (nitric acid), RE7 (hydrochloric acid), RE8 (thiourea + hydrochloric acid)).

Concentrations of metal ions (Ru, Pd, Hf, Ir, Pt, Au, Rh and Te) contained in solution B and recovery solutions RE1 to RE8 were analyzed by the ICP-AES method. FIG. 33(a) shows the metal ion removal rate of the column C1 determined by the analysis of the solution B and the recovery liquid RE1. (b) shows the metal ion removal rate of column C2 obtained by analysis of solution B and recovery liquid RE2. (c) shows the integrated recovery rate of metal ions in column C1 obtained by analysis of recovery liquids RE3 to RE5. (d) shows the integrated recovery rate of metal ions in column C2 obtained by analysis of recovered liquids RE6 to RE8. The integrated recovery rate is the integration of the recovery rate by nitric acid, the recovery rate by hydrochloric acid, and the recovery rate by thiourea + hydrochloric acid.

As shown in FIG. 33, column C1, like column C2, has a removal rate of about 70 to 100% for noble metal ions such as Au, Pt, Pd, Rh and Ir even at a low concentration of about 1 ppm. Indicated. Further, it was confirmed that the noble metal adsorbed on the column can be recovered by washing with the above nitric acid, the above hydrochloric acid, or the above thiourea-containing hydrochloric acid aqueous solution. Considering that the detection limit of the ICP-AES method is about 1 to 5 ppb, at a removal rate of 100%, it is possible to selectively adsorb and recover metal ions to the order of sub-ppb. Also, the organic porous material can be incinerated to recover only the noble metal. On the other hand, since silica gel does not disappear by incineration, it is difficult to recover precious metals by incineration.

(Separation of hydrophilic compounds and hydrophobic compounds by liquid chromatography)
Sample 2C was pulverized in a mortar and classified in the particle size range of 63/212 μm using a wire mesh sieve having mesh openings conforming to JIS Z8801. The classified porous material was packed in a stainless steel column (4.6 mm inner diameter×50 mm length) manufactured by GL Sciences to prepare an HPLC column C3.

The prepared column C3 was installed in an HPLC system LC-20AD manufactured by Shimadzu Corporation. Next, after injecting a sample containing uracil and naphthalene into column C3, a mixed solution of acetonitrile and water was separated under isocratic conditions at a flow rate of 1 mL/min. Separation was verified by a UV detector (detection wavelength 254 nm). FIG. 34 shows chromatographs obtained when the mixing ratio (by volume) of acetonitrile and water was changed to 75:25, 65:35, 50:50 and 40:60. In each graph, u means uracil and n means naphthalene.

As shown in Figure 34, naphthalene was detected first when the ratio of acetonitrile and water was 75:25 and 65:35. Uracil was detected first when the ratios of acetonitrile and water were 50:50 and 40:60. The organic porous material used in column C3 has, in its skeleton, interaction portions of both hydrophilic portions derived from amino groups, hydroxyl groups, etc. and hydrophobic portions derived from aromatic rings and carbon chains. It is presumed that when the concentration of the organic solvent is high, uracil is retained by interaction based on hydrogen bonding, and when the concentration of water is high, naphthalene is retained by hydrophobic interaction, and the separation shown in FIG. 34 was achieved. Ta. It was confirmed that column C3 can be used as a column for chromatography using hydrogen bonding and hydrophobic bonding.

The organic porous body obtained by the production method of the present invention can be used for various uses similar to conventional organic porous bodies.

Claims (12)

melamine and aldehyde monomers and/or oligomers of melamine and aldehyde monomers;
polyethylene oxide as a phase separation inducer;
In a solution system comprising a first solvent,
Formation of a melamine resin and spinodal decomposition of the solution system proceed by condensation polymerization of the monomer and/or the oligomer,
step (I) of forming a wet gel composed of said melamine resin-rich skeletal phase and said first solvent-rich solution phase;
By drying the wet gel, a skeleton based on the melamine resin is formed from the skeleton phase, macropores are formed from the solution phase, and an organic porous body having the skeleton and the macropores is formed. a step (II) of obtaining
including
The skeleton phase has pores with openings on the surface of the skeleton phase,
In the step (II), mesopores having openings on the surface are formed from the pores, and the organic porous structure has the mesopores and a hierarchical porous structure of the macropores and the mesopores. A method for producing an organic porous body to obtain a porous body. 2. The method for producing an organic porous material according to claim 1, wherein said oligomer is methylolmelamine. The wet gel has a co-continuous structure of the skeleton phase and the solution phase,
3. The method for producing an organic porous body according to claim 1, wherein the organic porous body has a co-continuous structure of the skeleton and the macropores. The method for producing an organic porous material according to any one of claims 1 to 3, wherein the pore size mode of the macropores is 0.1 µm or more and 10 µm or less. 5. The method for producing an organic porous material according to claim 1, wherein the mesopores have a pore diameter mode of 2 nm or more and 40 nm or less. 6. The production of the organic porous material according to any one of claims 1 to 5, wherein in the step (II), the wet gel is dried after the treatment for adjusting the pore diameter of the wet gel. Method. The method for producing an organic porous material according to any one of claims 1 to 6, wherein the solution system further contains a polymerization catalyst. The wet gel according to any one of claims 1 to 7, wherein in the step (II), the wet gel is dried after replacing the solvent contained in the wet gel from the first solvent with a second solvent different from the first solvent. A method for producing an organic porous material. 9. The method for producing an organic porous material according to claim 8, wherein the second solvent has a smaller surface tension and/or relative permittivity than the first solvent. 10. The method for producing an organic porous material according to claim 9, wherein the second solvent has a surface tension (20[deg.] C.) of 19.0 mN/m or less. 11. The method for producing an organic porous material according to any one of claims 1 to 10, wherein in the step (II), the wet gel is dried after the wet gel is impregnated with a liquid. 12. The method for producing an organic porous material according to claim 11, wherein the liquid impregnation treatment is hydrothermal treatment.

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