JP2011032117A - Method for manufacturing porous carbon and method for manufacturing electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing porous carbon and a method for manufacturing an electronic device. <P>SOLUTION: The method for manufacturing porous carbon includes a process for forming a hydrated polymer gel by polymerizing a phenolic compound and an aldehyde compound in the presence of a basic catalyst by using water as a solvent, a process for quickly freezing or slowly freezing the hydrated polymer gel, a process for freeze-drying the frozen hydrated polymer gel and a process for firing the freeze-dried hydrated polymer gel to form a carbonized gel, and the size of pore diameter is controlled by the time during which the hydrated polymer gel passes the maximum ice crystal formation range, and porous carbon which has a pore diameter of 1-1,000 μm is formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing porous carbon capable of controlling a pore size of 1 μm or more, and a method for producing an electronic device to which this production method is applied.

  Porous carbon is widely used in energy storage systems such as secondary batteries and capacitors, adsorbents, and supports for various metal catalysts.

  Conventionally, carbon gel, which is porous carbon, is prepared by, for example, resorcinol (R) and formaldehyde (F) being sol-gel polymerized under weak basicity, and drying the RF wet gel obtained by this polymerization to form a dry gel. It was prepared and carbonized under an inert atmosphere.

  As one method for producing porous carbon, a method using a wet gel is known (see, for example, Patent Document 1 and Patent Document 2 described later).

  First, Patent Document 1 below entitled “activated carbon” has the following description.

  As a manufacturing method of organic airgel (2), for example, a phenolic compound, an aldehyde compound, a basic catalyst, and an aqueous solvent are mixed together and usually stirred at 0 to 100 ° C., preferably 30 to 90 ° C. A method in which a wet gel is obtained and then dried; an aldehyde compound is usually mixed at 0 to 100 ° C., preferably 30 to 90 ° C., with a mixture comprising a phenolic compound, a basic catalyst and an aqueous solvent to obtain a wet gel. A method of drying after obtaining; after obtaining a wet gel by mixing a phenolic compound with a mixture comprising an aldehyde compound, a basic catalyst and an aqueous solvent, usually at 0 to 100 ° C., preferably 30 to 90 ° C. A method of drying; a basic catalyst in a mixture comprising a phenolic compound, an aldehyde compound and an aqueous solvent, usually at 0 to 100 ° C., preferably 30 After obtaining a wet gel by mixing at 90 ° C., a method for drying and the like. Among them, a method of obtaining a wet gel by mixing an aldehyde compound with a mixture comprising a phenolic compound, a basic catalyst and an aqueous solvent is preferred.

  Examples of the drying of the wet gel include a method of ventilating at room temperature to about 100 ° C. or drying under reduced pressure. In addition, when the solvent in the wet gel is water, after substitution with a hydrophilic organic solvent, a method of ventilating at room temperature to about 100 ° C. or drying under reduced pressure can be used. Examples of the hydrophilic organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, and t-butyl alcohol; aliphatic nitriles such as acetonitrile; aliphatic ketones such as acetone; dimethyl sulfoxide, and the like. Aliphatic sulfoxides; and aliphatic carboxylic acids such as acetic acid.

  As the hydrophilic organic solvent, t-butyl alcohol, dimethyl sulfoxide, and acetic acid are preferably used, and t-butyl alcohol is particularly preferable because it can be easily replaced with water. Moreover, it may replace with the method of ventilating at room temperature-about 100 degreeC, or drying under reduced pressure, and may perform freeze-drying. The temperature in lyophilization is usually in the range of −70 to 20 ° C., preferably in the range of −30 to 10 ° C. In addition, lyophilization is usually performed under vacuum. Further, as described in JP-A-9-328308, carbon dioxide or the like may be used for drying under supercritical conditions. As a method for drying a wet gel, lyophilization is preferred because there is little variation in pore volume due to drying.

  Further, Patent Document 2 described later entitled “Method for producing carbon material and electric double layer capacitor including the carbon material” includes the following description.

The invention of Patent Document 2 is a carbon material manufacturing method including the following steps [1] to [5], and an electric double layer capacitor including the carbon material.
[1] A step of producing a wet gel by reacting an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[2] A step of dehydrating the wet gel obtained in [1] to produce a dry gel.
[3] A step of preparing a rewet gel by impregnating and reacting the dry gel obtained in [2] with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[4] A step of dehydrating the rewet gel obtained in [3] to produce a re-dried gel.
[5] A step of firing the redried gel obtained in [4] to produce a carbon material.
[2] The step is a step of dehydrating the wet gel obtained in [1], and a dry gel can be obtained in this step. As a method for removing water from the wet gel, for example, direct water drying method, drying method under reduced pressure, heat drying method at about 30 to 150 ° C., freeze drying method at 0 ° C. or less, or these drying methods As a preferred embodiment, a method of removing the hydrophilic organic solvent after replacing the water in the wet gel with the hydrophilic organic solvent is recommended.

  Examples of the method for removing the hydrophilic organic solvent include a ventilation drying method, a vacuum drying method, a heat drying method at about 30 to 150 ° C., a freeze drying method at 0 ° C. or less, or a combination of these drying methods. The lyophilization method is preferable because it can retain the three-dimensional network structure of the particles constituting the wet gel made by the sol-gel reaction. That is, the liquid such as the hydrophilic organic solvent in the wet gel can be removed while maintaining the properties of the freeze-drying method and the functionally three-dimensional network structure.

  Furthermore, it is preferable to use a freeze-drying apparatus because the wet gel can be dried in a short time and the production cost of the dry gel can be reduced. The freezing temperature in lyophilization is usually in the range of −70 to 0 ° C., preferably in the range of −30 to −5 ° C.

  [3] The step is a step in which the dry gel obtained in the step [2] is impregnated with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst and reacted, and the dried gel has macropores, mesopores, etc. The pores, particularly the mesopores, were impregnated with an aqueous solution containing a phenolic compound, an aldehyde compound and a basic catalyst, and colloidal particles were formed from the aqueous solution to further form a three-dimensional network structure in the pores in the dried gel. This is a step of obtaining a wet gel.

  [4] The step is a step of dehydrating the impregnated gel obtained in the [3] step, and is a step of obtaining a re-dried gel. Specifically, it may be carried out in the same manner as the method exemplified in the section [2]. The [2] step and the [4] step may be performed under the same conditions or different conditions.

  [5] The step is a step of baking (carbonizing) the re-dried gel obtained in the [4] step to obtain a carbon material. Usually, it is performed in an inert gas atmosphere, and nitrogen, argon, helium, hydrogen, etc. are preferable as the inert gas at the time of firing (carbonization). The firing (carbonization) temperature is usually in the range of 200 to 3000 ° C., and in order to reduce the volume resistivity, it is preferably 800 ° C. or higher that can remove a functional group such as a carboxyl group, and graphitization is performed. In order to suppress, it is preferable that it is 1100 degrees C or less. The firing time is usually in the range of several minutes to several hours.

  First, terms used in the following explanation will be explained.

  “Organic polymer hydrogel (also referred to simply as polymer hydrogel)” is a hydrated organic polymer gel (also referred to simply as polymer gel), including water entrapped between organic polymer backbones, Also referred to as organic wet gel (also referred to simply as wet gel).

  “Organic polymer cryogel (also simply referred to as polymer cryogel or organic aerogel)” means a gel obtained by freeze-drying a polymer hydrogel and replacing the water contained in the gel with air.

  "Carbonized gel" shall mean a gel obtained by firing a polymer cryogel.

  Porous carbon is used in many fields such as the chemical field such as an adsorbent and a catalyst carrier, and the electronics field such as a highly conductive material. How to produce porous carbon having optimum pore characteristics corresponding to the purpose of using porous carbon is a very important issue.

  In order to improve the capacity of an energy storage system such as a secondary battery or a capacitor, porous carbon having a controlled pore size is required so as to best suit the application of the carbon material used. Similarly, regarding carbon materials used for adsorbents, supports for various metal catalysts, etc., porous carbons whose pore sizes are controlled so as to be most suitable for the applications are required. Conventionally, research and development on porous carbon with pore size of nanometer (nm) order has been active, but research and development on porous carbon with pore size of micrometer (μm) order has not progressed and is used There is a demand for a method for producing porous carbon in which the pore size is controlled to suit the application.

  For example, porous carbon has attracted attention as a support for catalysts used in fuel cells, but research and development so far has been conducted mainly on pores in the size range of 0.001 μm to 0.002 μm called micropores. It was related to porous carbon with These micropores are indispensable for realizing a large surface area, but pores larger than micropores and mesopores affect properties such as pore volume and bulk density.

  In fuel cells that use porous carbon for the catalyst layer and diffusion layer, the characteristics of the catalyst layer and diffusion layer, such as the fuel gas and oxidant gas permeability, moisture permeability, and mechanical strength, are porous. It depends greatly on the properties of carbonaceous material. In methanol fuel cells, the flooding phenomenon and methanol crossover are related to the size of the gaps in the diffusion layer and the catalyst layer. In order to improve the fuel cell characteristics, the size of the pores in the porous carbon is large. It is important to control so that the length is optimal. In order to realize a fuel cell with excellent characteristics, porous carbon with controlled pore size is required, and a method for producing porous carbon with controlled pore size is desired.

  Conventionally, in most methods for producing porous carbon using a wet gel, water is removed from the wet gel by replacing the water in the wet gel with a hydrophilic organic solvent and then removing the hydrophilic organic solvent. The way to do it is taken. As a method for removing the hydrophilic organic solvent, a vacuum drying method, a heat drying method, a freeze drying method, a supercritical drying method or the like is used, but a porous carbon having macropores of 1 μm or more and 1000 μm or less is manufactured. The drying method for doing so has not been studied so far.

  The present invention has been made to solve the above-described problems, and the object thereof is to apply a method for producing porous carbon capable of controlling a pore size of 1 μm or more, and this production method. An object is to provide a method for manufacturing an electronic device.

  That is, the present invention uses a phenol compound (for example, described later) in the presence of a basic catalyst (for example, sodium carbonate in the following embodiment) using water (for example, deionized water in the embodiment described later) as a solvent. A first step of polymerizing resorcinol) and an aldehyde compound (for example, formaldehyde in the embodiments described later) to produce an organic polymer hydrogel, and a second step of freezing the organic polymer hydrogel, A method for producing porous carbon, comprising: a third step of freeze-drying the frozen organic polymer hydrogel; and a fourth step of firing the freeze-dried organic polymer hydrogel to produce porous carbon. It is.

  The present invention also relates to an electronic device manufacturing method in which the above porous carbon manufacturing method is applied, and at least one of a catalyst carrier, a gas diffusion layer, and an electrode is formed by the porous carbon.

  According to the present invention, the first step of producing an organic polymer hydrogel by polymerizing a phenol compound and an aldehyde compound in the presence of a basic catalyst using water as a solvent, and the second step of freezing the organic polymer hydrogel. And having a third step of freeze-drying the frozen organic polymer hydrogel and a fourth step of firing the freeze-dried organic polymer hydrogel to produce porous carbon, so that the organic polymer hydrogel is incorporated into the organic polymer hydrogel. Since the organic polymer hydrogel is frozen without replacing the water with an organic solvent, porous carbon having pores of 1 μm or more can be produced at a low cost with fewer steps without using an expensive apparatus. A method for producing porous carbon that can be provided can be provided.

  According to the present invention, since the porous carbon production method is applied and at least one of the catalyst carrier, the gas diffusion layer, and the electrode is formed by the porous carbon, the target electron can be produced at low cost. An electronic device manufacturing method capable of manufacturing a device can be provided.

It is a figure explaining the manufacturing method of the carbon material in embodiment of this invention. It is a figure explaining the freezing method of the hydrated polymer gel same as the above. It is a figure explaining the outline | summary of a freezing curve same as the above. It is a figure explaining the outline | summary of the apparatus which freeze-drys the hydrated polymer gel same as the above. It is sectional drawing which shows the structural example of a direct methanol fuel cell (DMFC) same as the above. It is sectional drawing which shows the structural example of a polymer electrolyte fuel cell (PEFC) same as the above. It is sectional drawing explaining the outline | summary of the basic composition of an electric double layer capacitor same as the above. It is sectional drawing explaining the outline | summary of the basic composition of a hybrid capacitor same as the above. It is sectional drawing explaining the outline | summary of the basic composition of a redox capacitor same as the above. It is a figure explaining the manufacturing method of carbonized gel in the Example of this invention. It is a figure which shows the optical microscope image of a polymer cryogel same as the above. It is a figure which shows the optical microscope image of a polymer cryogel same as the above. It is a figure which shows the scanning electron microscope image of carbonization gel same as the above. It is a figure explaining logarithmic differential pore volume distribution of carbonization gel same as the above. It is a figure explaining the characteristic comparison of carbonization gel and commercial item carbon same as the above. It is a figure which shows the optical microscope image of a polymer cryogel same as the above. It is a figure which shows the scanning electron microscope image of carbonization gel same as the above. It is a figure which shows the scanning electron microscope image of carbonization gel same as the above.

  In the method for producing porous carbon of the present invention, in the second step, the pore size may be controlled by the time during which the organic polymer hydrogel passes through the maximum ice crystal formation zone. According to such a configuration, the porous polymer having the desired pore diameter can be obtained by controlling the size of the ice crystals that are the source of the pores according to the time during which the organic polymer hydrogel passes through the maximum ice crystal formation zone. Can be generated. The maximum ice crystal formation zone reaches a temperature (freezing point) at which the water contained in the organic polymer hydrogel turns into ice, and a temperature range from about 0 ° C. to −5 ° C. to −7 ° C. at which ice crystals are formed. Meaning, the time for passing through the maximum ice crystal formation zone is the time during which the organic polymer hydrogel is at the temperature of the maximum ice crystal formation zone and ice crystals are formed (that is, the freezing time).

  Moreover, it is good to set it as the structure which produces | generates the porous carbon whose said pore diameter is 1 micrometer or more and 1000 micrometers or less. According to such a configuration, the porous carbon having the pore diameter in the range of 1 μm or more and 1000 μm or less can be generated by controlling the time during which the organic polymer hydrogel passes through the maximum ice crystal formation zone. it can.

  Moreover, it is good to set it as the structure by which the said pore diameter is controlled by the range of 1 micrometer or more and 100 micrometers or less by rapidly freezing the said organic polymer hydrogel. According to such a configuration, the porous carbon having the pore diameter in the range of 1 μm or more and 100 μm or less can be generated by controlling the time during which the organic polymer hydrogel passes through the maximum ice crystal formation zone. it can.

  Further, it is preferable that the pore diameter is controlled in a range of 10 μm or more and 30 μm or less by rapidly freezing the organic polymer hydrogel. According to such a configuration, the porous carbon having the pore diameter in the range of 10 μm or more and 30 μm or less is controlled by controlling the organic polymer hydrogel to pass through the maximum ice crystal formation zone. Can be generated.

  The organic polymer hydrogel may be cooled to a temperature of 63K or higher and 77K or lower. According to such a configuration, the organic polymer hydrogel can be rapidly frozen in a short time using inexpensive liquid nitrogen.

  Further, it is preferable that the pore diameter is controlled in a range of 1 μm or more and 2 μm or less by rapid freezing after dividing the organic polymer hydrogel into small pieces. According to such a configuration, the organic polymer hydrogel can be rapidly frozen efficiently, and the pore diameter can be 1 μm or more and 2 μm or less.

  Moreover, it is good to set it as the structure frozen by spraying the dispersion solution which disperse | distributed the said organic polymer hydrogel in water. According to such a configuration, the organic polymer hydrogel formed into fine droplets by spraying can be quickly and efficiently frozen.

  The sprayed droplets of the dispersion solution may be cooled to a temperature of 63K or higher and 77K or lower. According to such a configuration, the organic polymer hydrogel can be rapidly frozen in a short time using inexpensive liquid nitrogen.

  Moreover, it is good to set it as the structure by which the said pore diameter is controlled in the range of 100 micrometers or more and 1000 micrometers or less by making the said organic polymer hydrogel freeze slowly. According to such a configuration, the porous carbon having the pore diameter in the range of 100 μm or more and 1000 μm or less can be generated by controlling the time during which the organic polymer hydrogel passes through the maximum ice crystal formation zone. it can.

  Moreover, it is good to set it as the structure by which the said pore diameter is controlled by the range of 500 micrometers or more and 1000 micrometers or less by making the said organic polymer hydrogel freeze slowly. According to such a configuration, the porous carbon having the pore diameter in the range of 500 μm or more and 1000 μm or less is controlled by controlling the organic polymer hydrogel to pass through the maximum ice crystal formation zone longer. Can be generated.

  The organic polymer hydrogel may be cooled to a temperature of 200K or higher and 273K or lower. According to such a structure, the said organic polymer hydrogel can be frozen using a general purpose low-cost apparatus.

  The organic polymer hydrogel may be frozen in a refrigerator or freezer. According to such a configuration, the time for the organic polymer hydrogel to pass through the maximum ice crystal formation zone can be controlled by controlling the operating temperature condition of the refrigerator or the freezer.

  In the first step, the phenol compound, the aldehyde compound, and the basic catalyst are dissolved in the solvent and then heated to a temperature of 355 K or more and 365 K or less. Is good. According to such a configuration, there is no excessive evaporation of water as the solvent, the reaction rate of sol-gel polymerization in an aqueous solution of the phenol compound and the aldehyde compound is increased, and the uniform is efficiently performed. Organic polymer hydrogels can be produced.

  The phenol compound is preferably resorcinol, the aldehyde compound is formaldehyde, and the basic catalyst is sodium carbonate. According to such a configuration, it is possible to generate hydrocarbons at other schools with an inexpensive material.

  The organic polymer hydrogel preferably contains 95% by mass to 97% by mass of water. According to such a configuration, porous carbon having a pore diameter of 1 μm or more and 1000 μm or less can be generated.

  In the fourth step, the freeze-dried organic polymer hydrogel may be fired under an inert gas at atmospheric pressure. According to such a configuration, the organic polymer hydrogel can be carbonized without loss due to oxidation.

  In addition, the freeze-dried organic polymer hydrogel may be fired at a temperature of 873 K or higher and 1473 K or lower. According to such a configuration, activated porous carbon can be generated.

  In the electronic device manufacturing method of the present invention, the electronic device may be configured as a fuel cell, an electric double layer capacitor, a hybrid capacitor, or a redox capacitor. According to such a configuration, it is possible to provide an electronic device manufacturing method capable of manufacturing an electronic device at low cost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Embodiment]
<Method for producing porous carbon>
In the present invention, a phenol compound and an aldehyde compound are polymerized in an aqueous solution in the presence of a basic catalyst, and a polymer formed by the polymerization reaction is finally passed through a sol state in which the aqueous solution is contained. To form an organic wet gel containing water. Then, the wet gel is frozen under a controlled time for the wet gel to pass through the maximum ice crystal formation zone, followed by drying by freeze-drying, and a dry gel (organic aerogel) having a controlled pore size. Can be fired under an inert atmosphere and carbonized to obtain porous carbon having a controlled pore size. When freezing the wet gel, as will be described later with reference to FIG. 3, the time for allowing the wet gel to pass through the maximum ice crystal formation zone (the time during which the wet gel is placed at the temperature of the maximum ice crystal formation zone and ice crystals are formed (freezing time)) By controlling this, the size of the ice crystal that is the source of the pores can be controlled.

  FIG. 1 is a diagram for explaining a method for producing porous carbon in an embodiment of the present invention.

  As shown in FIG. 1, first, a phenol compound and an aldehyde compound are mixed using water as a solvent in the presence of a basic catalyst, an acid is added to dissolve the solid phase, and then the phenol compound is heated. The compound and the aldehyde compound are polymerized to form a hydrated polymer gel (organic polymer hydrogel or organic wet gel).

  The organic wet gel is then rapidly or slowly frozen, followed by lyophilization of the frozen organic wet gel to produce a polymer cryogel (organic aerogel), and finally the polymer cryogel is inerted The porous carbon is obtained by calcination and carbonization below. The porous carbon thus obtained is pulverized so as to have a desired particle size.

  Hereinafter, generation of a hydrated polymer gel (organic polymer hydrogel), freezing of an organic polymer hydrogel, generation of a polymer cryogel, and generation of a carbonized gel will be described in more detail.

(Formation of hydrated polymer gel)
Hydrated polymer gel (organic polymer hydrogel) uses distilled water and ion-exchanged water as a solvent, and polymerizes a phenol compound and an aldehyde compound in the presence of a basic catalyst to form an organic polymer hydrogel. However, as the phenol compound, for example, resorcinol (m-dioxybenzene), hydroquinone (p-dioxybenzene), catechol (o-dioxybenzene), and phenol can be used. Moreover, formaldehyde, paraformaldehyde, acetaldehyde, and butyraldehyde can be used as an aldehyde compound. Formaldehyde is water-soluble, has good reactivity with phenolic compounds, and can efficiently perform a sol-gel reaction. As basic catalysts, water-soluble alkali or alkaline earth metal hydroxides or carbonates such as sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), lithium carbonate (Li ₂ CO) ₃ ), sodium hydroxide (NaOH), potassium hydroxide (KOH) can be used.

  Preferable specific examples include resorcinol as a phenol compound, formaldehyde as an aldehyde compound, sodium carbonate as a basic catalyst, and an aqueous solution in which these are dissolved by addition of an acid at a temperature of 355 K or more and 365 K or less. The temperature is raised, and the sol-gel reaction proceeds to form an organic polymer hydrogel containing 95% by mass or more and 97% by mass or less of water.

  Next, freezing of the organic polymer hydrogel will be described.

(Freezing organic polymer hydrogel)
FIG. 2 is a diagram for explaining a method of freezing a hydrated polymer gel (wet gel) according to an embodiment of the present invention. FIG. 2 (A) and FIG. 2 (B) are quick freezing and FIG. ) Is a diagram for explaining slow freezing.

  FIG. 3 is a diagram for explaining the outline of the freezing curve in the embodiment of the present invention.

  The freezing curve shown in FIG. 3 shows changes in the temperature of the object to be frozen over time when the object to be frozen (here, a wet gel) is frozen, and the vertical axis represents the object to be frozen. The temperature and horizontal axis indicate the passage of time.

  In general, when the object to be frozen is placed in a cooling environment, the temperature of the object to be frozen decreases with time, reaches the freezing point of the object to be frozen (the temperature at which water turns into ice), and generates approximately 0 ice crystals. It passes through the temperature zone from ℃ to -5 ℃ to -7 ℃ (referred to as the “maximum ice crystal formation zone”), and the temperature of the object to be frozen decreases with the passage of time. Go down. The cooling environment is given by, for example, a refrigerant made of solid carbon and an organic solvent, a refrigerant such as liquid nitrogen or liquid oxygen, a refrigerator, a freezer, or the like.

  In the zone from about 0 ° C. to −5 ° C. to −7 ° C., called the maximum ice crystal formation zone shown in FIG. 3, the water contained in the object to be frozen changes to ice, and the heat of cooling is required for the formation of ice crystals. This zone is consumed as latent heat and promotes the growth of ice crystals. Therefore, the passage time (T) passing through the maximum ice crystal formation zone, in other words, the time (T) when the object to be frozen is placed in the maximum ice crystal formation zone and ice crystals are generated (hereinafter referred to as “freezing time”). )), The size of ice crystals generated from the water contained in the object to be frozen differs.

  As shown by the freezing curve on the right side shown in FIG. 3, in the quick freezing that rapidly passes through the ice crystal formation zone in a short time, a large number of fine crystal ice crystals are generated in the object to be frozen. On the other hand, in the slow freezing shown in the left freezing curve shown in FIG. 3 and slowly passing the maximum ice crystal formation zone over time, a small number of large ice crystals are generated in the object to be frozen. In FIG. 3, the freezing time (T) in rapid freezing is denoted by Tr, and the freezing time (T) in slow freezing is denoted by Ts.

  In the present invention, by controlling the time (T) during which the wet gel passes through the maximum ice crystal formation zone (T), the size of the ice crystals that finally become the source of pores generated in the carbonized gel is reduced. The pore diameter of the carbonized gel can be controlled in the range of 1 μm or more and 1000 μm or less.

  FIG. 2 (A) shows an example in which a fragmented hydrated polymer (wet gel) is put into liquid nitrogen and rapidly frozen. Cooling the wet gel to a temperature of 63K or more and 77K or less using liquid nitrogen, for example, changing the size of the wet gel to be frozen, etc., so that the freezing time (Tr) in quick freezing becomes a short time. By controlling, the pore diameter can be controlled in the range of 1 μm to 100 μm, or in the range of 10 μm to 30 μm.

  FIG. 2 (B) shows an example in which the atomized hydrated polymer (wet gel) is rapidly frozen in liquid nitrogen. The wet gel is divided into fine pieces and dispersed in water. The dispersion is sprayed onto liquid nitrogen, and the mist (droplet) containing the wet gel is cooled to a temperature of 63K or higher and 77K or lower to form a fine frozen body. The pore diameter can be controlled in the range of 1 μm or more and 2 μm or less by rapid freezing so that the freezing time (Tr) is short.

  FIG. 2 (C) shows that the fragmented hydrated polymer (wet gel) is put in a freezing storage to control the temperature in the refrigerator, and the wet gel is cooled to a temperature of 200 K or more and 273 K or less, for example. An example of slow freezing. For example, by controlling the freezing time (Ts) by changing the size of the wet gel to be frozen or by controlling the temperature in the freezer so that the freezing time (Ts) is long, The pore diameter can be controlled in the range of 100 μm or more and 1000 μm or less, or in the range of 500 μm or more and 1000 μm or less. It goes without saying that the freezing of the wet gel can be performed by using a cooling storage that can be cooled to -10 ° C or lower instead of the freezer.

  Next, production of a polymer cryogel by freeze drying of a frozen wet gel will be described.

(Freeze drying of frozen wet gel: production of polymer cryogel)
The examples that are lyophilized are those obtained by rapid freezing shown in FIG. 2 (A) or FIG. 2 (B) ((A) or (B) shown in FIG. 4) in liquid nitrogen. A frozen wet gel, or one obtained by slow freezing as shown in FIG. 2C (FIG. 4C), and a frozen wet gel in a freezing container of a freezer.

  As shown in FIG. 4, a freeze-drying (freeze-drying) apparatus includes a vacuum chamber that is evacuated by an exhaust pump, a heating stage that is placed in the vacuum chamber and heated by a heat medium, and a cold trap that is held at a low temperature by a refrigerator. It is composed of The outline of freeze-drying is as follows.

  For example, under a pressure of 0.1 mmHg, 1 g of ice evaporates and expands to 10,000 L, so that it cannot be practically exhausted by only an exhaust pump. In the freeze-drying apparatus, water vapor sublimated from a frozen object to be dried (here, a frozen polymer hydrogel) has the same volume in a cold trap (for example, a freezing pipe) held at a low temperature by a refrigerator. Because it is solidified as ice, the cold trap plays the role of an exhaust pump. The degree of vacuum in the apparatus is always kept low, the temperature of the object to be dried is kept at a low temperature corresponding to the saturated vapor pressure, the water sublimation proceeds, and the object to be dried is dehydrated. The exhaust pump is used to exhaust the air in the apparatus at the beginning of drying, and is used to exhaust non-condensable gas that has not been trapped by the cold trap in the drying process.

  The heat energy from the heat source is applied to the heat medium through the heat exchanger, the heating stage is heated by the heat medium, and is transmitted as sublimation latent heat to the object to be dried. The heat is released to the cooling water of the cooler. The sublimation of water from the drying target proceeds, and as the amount of water sublimation decreases, the heat supplied from the heating stage increases, the heat balance is lost, and the temperature of the drying target increases. By using a freeze-drying apparatus, a wet gel can be dried in a short time at a low cost, and a polymer cryogel can be produced.

  In the above description, the freezing of the wet gel and the freeze drying of the frozen wet gel have been described separately. However, the freezing of the wet gel and the freeze drying of the frozen wet gel are performed in the freeze drying apparatus shown in FIG. Needless to say, it can be performed continuously.

  Next, the production | generation of the carbonized gel by baking processing of a polymer cryogel is demonstrated.

(Baking of polymer cryogel: generation of carbonized gel)
The polymer cryogel is baked at a temperature of 873 K or more and 1473 K or less under an inert gas at atmospheric pressure to obtain a carbonized gel, and activated porous carbon is obtained. The obtained porous carbon is made into a desired particle size according to the purpose of use using a pulverizer.

  The porous carbon obtained in this way can be used for various electronic devices. The electronic device includes, for example, a fuel cell comprising porous carbon as a support on which a platinum catalyst is supported, porous carbon. A fuel cell having a gas diffusion layer formed using, a secondary battery having an electrode formed using porous carbon, and a capacitor having an electrode formed using porous carbon (electricity Double layer capacitor, hybrid capacitor, redox capacitor) and the like.

  Needless to say, the porous carbon can be used as an adsorbent of various chemical species and as a support for a catalyst for a general chemical reaction.

  Next, a fuel cell to which the porous carbon according to the present invention is applied will be described.

<Fuel Cell for Porous Carbon According to the Present Invention>
The catalyst layer and the gas diffusion layer formed by applying the porous carbon according to the present invention can be used for a fuel cell. Next, an example of this fuel cell will be described.

  FIG. 5 is a cross-sectional view illustrating a configuration example of a DMFC (direct methanol fuel cell) according to the embodiment of the present invention.

  As shown in FIG. 5, the methanol aqueous solution is flowed from the inlet 26a of the fuel supply section (separator) 50 having a flow path to the passage 27a as the fuel 25, through the conductive gas diffusion layer 24a as the base, The catalyst electrode 22a held by the gas diffusion layer 24a is reached, and according to the anode reaction shown in the lower part of FIG. 5, methanol and water react on the catalyst electrode 22a to generate hydrogen ions, electrons, and carbon dioxide. The exhaust gas 29a containing is discharged from the outlet 28a. The generated hydrogen ions pass through the polymer electrolyte membrane 23 formed by the proton-conducting composite electrolyte, and the generated electrons pass through the gas diffusion layer 24a and the external circuit 70, and further, conductive gas diffusion as a substrate. The catalyst electrode 22b held by the gas diffusion layer 24b is reached through the layer 24b.

  As shown in FIG. 5, air or oxygen 35 flows from the inlet 26b of the air or oxygen supply section (separator) 60 having a flow path to the passage 27b, passes through the gas diffusion layer 24b, and passes through the gas diffusion layer 24b. Reaching the retained catalyst electrode 22a, hydrogen ions, electrons, and oxygen react on the catalyst electrode 22b according to the cathode reaction shown in the lower part of FIG. 5 to produce water, and the exhaust gas 29b containing water is discharged from the outlet 28b. Is done. As shown in the lower part of FIG. 5, the entire reaction is a methanol combustion reaction in which electric energy is extracted from methanol and oxygen and water and carbon dioxide are discharged.

  FIG. 6 is a cross-sectional view illustrating a configuration example of a PEFC (polymer electrolyte fuel cell) according to the embodiment of the present invention.

  As shown in FIG. 6, the humidified hydrogen gas flows as fuel 25 from the inlet 26a of the fuel supply unit 50 to the passage 27a, passes through the gas diffusion layer 24a, and reaches the catalyst electrode 22a. In accordance with the anode reaction shown in FIG. 2, hydrogen ions and electrons are generated from the hydrogen gas on the catalyst electrode 22a, and the exhaust gas 29a containing excess hydrogen gas is discharged from the outlet 28a. The generated hydrogen ions pass through the polymer electrolyte membrane 23 formed by the proton conductive composite electrolyte, and the generated electrons pass through the gas diffusion layer 24a and the external circuit 70, and further pass through the gas diffusion layer 24b to form a catalyst. It reaches the electrode 22b.

  As shown in FIG. 6, air or oxygen 35 flows from the inlet 26b of the air or oxygen supply section 60 to the passage 27b, reaches the catalyst electrode 22a through the gas diffusion layer 24b, and is shown in the lower part of FIG. According to the cathode reaction, hydrogen ions, electrons, and oxygen react on the catalyst electrode 22b to generate water, and the exhaust gas 29b containing water is discharged from the outlet 28b. As shown in the lower part of FIG. 6, the entire reaction is a hydrogen gas combustion reaction in which electric energy is extracted from hydrogen gas and oxygen and water is discharged.

  5 and 6, the polymer electrolyte membrane 23 is formed by binding a proton conductive composite electrolyte with a binder (eg, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.). Has been. The anode 20 and the cathode 30 are separated by the polymer electrolyte membrane 23, and hydrogen ions and water molecules move through the polymer electrolyte membrane 23. The polymer electrolyte membrane 23 is a membrane having high hydrogen ion conductivity, preferably chemically stable and high in mechanical strength.

  5 and 6, the catalyst electrodes 22a and 22b constitute a conductive substrate as a current collector and are formed in close contact with gas diffusion layers 24a and 24b that are permeable to gases and solutions. Has been. The gas diffusion layers 24a and 24b are made of, for example, a porous substrate such as carbon paper, a carbon molded body, a carbon sintered body, a sintered metal, and a foam metal. In order to prevent a decrease in gas diffusion efficiency due to water generated by driving the fuel cell, the gas diffusion layer is subjected to water repellent treatment with a fluororesin or the like.

  The catalyst electrodes 22a and 22b are made of, for example, a carrier on which a catalyst made of platinum, ruthenium, osmium, platinum-osmium alloy, platinum-palladium alloy or the like is supported by a binder (eg, polytetrafluoroethylene, polyvinylidene fluoride ( PVDF), etc.)). As the carrier, for example, acetylene black, carbon such as graphite, inorganic fine particles such as alumina and silica are used. A solution in which carbon particles (catalyst metal is supported) is dispersed in an organic solvent in which the binder is dissolved is applied to the gas diffusion layers 24a and 24b, and the organic solvent is evaporated and bound by the binder. The attached film-like catalyst electrodes 22a and 22b are formed.

  The polymer electrolyte membrane 23 is sandwiched between catalyst electrodes 22a and 22b formed in close contact with the gas diffusion layers 24a and 24b, thereby forming a membrane-electrode assembly (MEA) 40. The anode 20 is constituted by the catalyst electrode 22a and the gas diffusion layer 24a, and the cathode 30 is constituted by the catalyst electrode 22b and the gas diffusion layer 24b. The anode 20 and the cathode electrode 30 are in close contact with the polymer electrolyte membrane 23, the proton conductor enters between the carbon particles, and the catalyst electrodes 22a and 22b are impregnated with the polymer electrolyte (proton conductor). The catalyst electrodes 22a, 22 and the polymer electrolyte membrane 23 are closely bonded to each other, and high conductivity of hydrogen ions is maintained at the bonding interface, and electric resistance is kept low.

In the examples shown in FIGS. 5 and 6, the openings of the fuel 26 inlet 26a, the exhaust gas 29a outlet 28a, the air or oxygen (O ₂ ) 35 inlet 26b, and the exhaust gas 29b outlet 28b are provided with a polymer. Although arranged perpendicularly to the surfaces of the electrolyte membrane 23 and the catalyst electrodes 22a and 22b, the openings are arranged in parallel to the surfaces of the polymer electrolyte membrane 23 and the catalyst electrodes 22a and 22b. Various modifications can be made with respect to the arrangement of the openings.

  The fuel cells shown in FIGS. 5 and 6 can be manufactured by using general methods known in various literatures, and thus detailed description on the manufacturing will be omitted.

  Next, a capacitor to which the porous carbon according to the present invention is applied will be described.

<Electric double layer capacitor to which porous carbon according to the present invention is applied>
FIG. 7 is a cross-sectional view for explaining the outline of the basic configuration of the electric double layer capacitor in the embodiment of the present invention.

  As shown in FIG. 7, an electric double layer capacitor (EDC) includes a polarizable electrode (positive electrode) 10a and a polarizable electrode (negative electrode) 10b arranged with a separator 13 interposed therebetween, and a polarizable electrode. A current collector 12 joined to each of (positive electrode) 10a and polarizable electrode (negative electrode) 10b, and gasket 14 made of an electrically insulating resin that is insoluble and corrosion resistant to the electrolyte, and is hermetically sealed. It is configured. Each of the polarizable electrode (positive electrode) 10a and the polarizable electrode (negative electrode) 10b is an electrode made of porous carbon, and is impregnated with an electrolyte solution in which an electrolyte is dissolved in an aprotic solvent. Electric charges are stored in an interface (electric double layer) formed between the polarizable electrodes 10a and 10b and the electrolyte, and electric energy is stored.

  Examples of the electrolyte include tetraalkylammonium salts, quaternary ammonium salts having an alkylene group, phosphonium salts, and oniums such as ammonium halide salts in which at least one of H of these alkyl groups or alkylene groups is substituted with a halogen such as F. An ion dissociable salt composed of a salt or the like is used.

  Examples of the aprotic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate, chain carbonates such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate, γ-butyrolactone, γ-valerolactone and the like. Used as cyclic carboxylic acid esters, chain carboxylic acid esters such as methyl acetate and methyl propionate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, nitriles such as 3-methoxypropionitrile, sulfolane, trimethyl phosphate, etc. Is done.

  The separator is made of an electrically insulating resin having a high ion permeability, insoluble in an electrolyte and having corrosion resistance, a porous film made of glass fiber, ceramics, or the like, a nonwoven fabric or papermaking, and is impregnated with an electrolyte solution. As the current collector, for example, a metal such as copper, stainless steel, or aluminum alloy is used.

<Hybrid capacitor to which porous carbon according to the present invention is applied>
FIG. 8 is a cross-sectional view for explaining the outline of the basic configuration of the hybrid capacitor in the embodiment of the present invention.

  A hybrid capacitor is a device that stores electricity by charging lithium ions between layers of carbon such as graphite at the negative electrode during charging, and forming an electric double layer by attracting anions of electrolyte to the electrode surface at the positive electrode.

  As shown in FIG. 8, the hybrid capacitor has a configuration in which the polarizable electrode (negative electrode) 10b is replaced with the graphite electrode (negative electrode) 10c similar to the negative electrode of the lithium ion secondary battery in the electric double layer capacitor shown in FIG. Have.

As the electrolyte, a combination of a lithium cation and an inorganic anion is used, and the inorganic anion is at least one selected from the group consisting of BF ₄ ⁻ , PF ₆ ⁻ and ClO ₄ ⁻ . As the organic polar solvent contained in the electrolyte solution, cyclic carbonates such as propylene carbonate, ethylene carbonate and butylene carbonate, chain carbonates such as dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate, γ-butyrolactone, and the like are used.

<Redox capacitor to which porous carbon according to the present invention is applied>
FIG. 9 is a cross-sectional view for explaining the outline of the basic configuration of the redox capacitor in the embodiment of the present invention.

  A redox capacitor is a capacitor that expands the capacity of an electric double layer capacitor by using a pseudo-capacitance. For storage and release of electric energy, redox of an electrode material, charge / discharge in an electric double layer, ions on an electrode surface It utilizes the desorption of.

As shown in FIG. 9, the redox capacitor is the same as the electric double layer capacitor shown in FIG. 7, but the polarizable electrode (positive electrode) 10 a and the polarizable electrode (negative electrode) 10 b are respectively an electrode (positive electrode) 10 d and an electrode (negative electrode) 10. It has the structure replaced with. The electrode (positive electrode) 10d and the electrode (negative electrode) 10 are electrodes made of porous carbon, respectively, and are impregnated with an electrolyte solution containing an active material. The active material is a transition metal oxide such as ruthenium, a transition metal hydroxide, a conductive polymer, or the like. As an electrolyte solution, when a transition metal oxide such as ruthenium or a transition metal hydroxide is used as an active material, an aqueous solution of sulfuric acid is used as an electrolyte solution, and a conductive polymer is used as an active material, LiBF ₄ , LiPF ₆ , LiClO ₄ An organic solvent in which an electrolyte such as a lithium salt is dissolved and dissociated is used as an electrolytic solution. The aprotic solvent used in the electric double layer capacitor is used as the solvent contained in the electrolyte solution.

  Next, examples relating to porous carbon will be described.

  In an embodiment of the present invention, a hydrated resorcinol-formaldehyde polymer gel (wet gel) composed of a network structure in which resorcinol and formaldehyde are polymerized and interconnected with water is synthesized by a sol-gel process. Is done.

  When this wet gel is frozen, water taken into the gel is crystallized to form hexagonal ice crystals, so that the network structure of the gel becomes discrete. The size of the ice crystals can be controlled by changing the time that the wet gel passes through the maximum ice crystal formation zone.

  The rapid freezing of the wet gel produces small ice crystals, and the ice crystals are sublimated from the place where the small ice crystals are formed by post-treatment (freeze drying). For example, the fine gel having a size of 1 μm or more and 100 μm or less. Will result in holes. The quick freezing of the wet gel is performed, for example, by placing the wet gel in liquid nitrogen or other methods. The slow freezing of the wet gel forms larger ice crystals, and the ice crystals are sublimated from the place where the larger ice crystals are generated by post-treatment (freeze drying). For example, the size is 100 μm or more and 1000 μm or less. Will result in pores having. The slow freezing of the wet gel is performed, for example, by placing the wet gel in a freezer at −10 ° C. or other methods.

  By freezing the wet gel in this way and further freeze-drying, water is removed from the wet gel, and a low-density, porous resorcinol-formaldehyde polymer gel (organic aerogel) is formed.

  This organic aerogel is carbonized by heat treatment in an inert gas at atmospheric pressure to form a carbonized gel.

  In the method according to the embodiment of the present invention, since the pore diameter of the carbonized gel finally formed is determined by the size of the ice crystals formed in the freezing process of the wet gel, the wet gel has a maximum ice crystal formation zone. It was possible to adjust the size of the pore diameter by changing the time required to pass through, and to synthesize porous carbon having pores having a size in the range of 1 μm or more and 1000 μm or less.

  In the conventional method, in most cases, only porous carbon having pores with a size in the range of 0.5 nm to 10 nm is synthesized. In the conventional method, water is once substituted from the wet gel with the organic solvent, and then the organic solvent is removed. In the embodiment of the present invention, the sol in the aqueous solution is used without using the organic solvent. -Freeze the wet gel formed by the gel process without organic solvent substitution and remove the water by freeze-drying.

[Example 1]
FIG. 10 is a diagram illustrating a method for producing a carbonized gel in an example of the present invention.

  As shown in FIG. 10, first, a hydrated polymer gel (wet gel) is generated. As shown in FIG. 2 (A), after the wet gel is broken into pieces and this wet gel is frozen, it is then lyophilized to form a polymer cryogel, and finally it is baked to form a carbonized gel.

(Generation of wet gel)
Resorcinol (C ₆ H ₆ O ₂ ) 4 g, formaldehyde (HCHO) (10% aqueous solution) 6 g, deionized water 190 mL, sodium carbonate (Na ₂ CO ₃ ) 0.08 g can be sealed in a plastic container (volume 500 mL) While stirring with a magnetic stir bar, 5% nitric acid (HNO ₃ ) was added dropwise until the solid phase dissolved and the pH reached 6.0. The plastic container was sealed and placed in a heating furnace maintained at 87 ° C. for 24 hours. As a result, the gel formed (wet gel) was firm and occupied about 200 mL of the sealed plastic container. After cooling this gel to room temperature, the gel was agitated with a glass rod to make small pieces to obtain gel pieces having a size of about 1 cm ³ . The gel pieces were placed in a large Bucher funnel and the gel pieces were washed repeatedly with water.

(Quick freeze and freeze-drying of wet gel)
Next, the wet gel piece was put into a deer bottle containing liquid nitrogen. After the gel pieces are completely frozen, place the frozen gel in an evacuation vessel and evacuate the evacuation vessel through a cold trap until the vacuum pressure stabilizes and the ice is removed. Then, freeze-drying was performed to obtain a freeze-dried polymer (polymer cryogel). The time for lyophilization was 120 hours.

(Baking of polymer cryogel (generation of carbonized gel))
The polymer cryogel was transferred to an alumina container and heated to 1050 ° C. to carbonize the polymer cryogel to obtain a carbonized gel. The carbonized gel was pulverized and powdered. In this way, porous carbon was obtained.

  FIG. 11 is a diagram showing an optical microscope image (magnification: 35 times) of the polymer cryogel obtained in the example of the present invention.

In the optical microscope image of a polymer cryogel having a size of about 1 cm ³ and a magnification of 35 times shown in FIG. 11, no pores are observed.

  FIG. 12 is a diagram showing an optical microscopic image (magnification: 450 times) of the polymer cryogel obtained in the example of the present invention.

  As shown in FIG. 12, pores having a size of about 40 μm are observed as dark regions in the polymer cryogel.

  FIG. 13 is a view showing a scanning electron microscope image (magnification: 500 times) of the carbonized gel obtained in the example of the present invention.

  As shown in FIG. 13, pores having a size of about 40 μm are observed as dark regions, similarly to the polymer cryogel shown in FIG. 12.

  FIG. 14 is a diagram showing the relationship between the pore diameter and the pore volume of the carbonized gel obtained in the example of the present invention, and is a diagram for explaining the logarithmic differential pore volume distribution. In FIG. The pore diameter (Pore size diameter, μm), and the vertical axis represents logarithmic differential pore volume (Log deferential Intrusion, dV / d (logD)) (mL / g)).

  As shown in FIG. 14, the logarithmic differential pore volume distribution shows a peak centered on a pore diameter of about 45 μm, indicating the presence of main pores. Moreover, it has shown that the pore which has a diameter of about 20 micrometers or less does not exist. FIG. 14 shows the result of measuring the pore diameter distribution by mercury porosimetry with a sample set in automatic porosimeter autopore IV9500 (manufactured by SHIMAZU).

  FIG. 15 is a diagram illustrating a comparison of characteristics obtained from nitrogen adsorption regarding the carbonized gel obtained in the example of the present invention and commercial carbon.

  In FIG. 15, commercially available carbon is Ketjen Black (registered trademark), specifically Ketjen Black 900, and carbonized gel A and carbonized gel B are carbonized gels produced as follows.

  The carbonized gel A was prepared by freezing an aqueous solution (pH = 6) of 3% wet gel (hydrated resorcinol-formaldehyde polymer gel) prepared by the above-described method in liquid nitrogen, and then vacuum lyophilizer (EYELA). It was freeze-dried at −80 ° C. using Tokyo Rika Kikai FDU-2100). The freeze-dried polymer cryogel was transferred to an alumina container and heated to 1050 ° C. to carbonize the polymer cryogel to obtain a carbonized gel A. The carbonized gel B is obtained by further heating the carbonized gel A to 450 ° C. under a dry air flow.

V _m (cm ³ / g) is an adsorption amount required to form a monomolecular layer in the BET formula, A _s (m ² / g) is a specific surface area, and V _p (cm ³ / g g) is the total pore volume.

Average carbon gels A, carbon gels B A _s represents a substantially same value as 892 (m ² / g) and is Ketjenblack (registered trademark), carbon gels A, V carbonization Gel B The average value of _m is 204.5 (cm ³ / g), which is substantially the same value as Ketjen Black (registered trademark). V _p and A _p for carbonized gel A and carbonized gel B each show a smaller value than Ketjen Black (registered trademark), and R _{p for} carbonized gel A and carbonized gel B is larger than Ketjen black (registered trademark). The value is shown.

[Example 2]
In Example 1, the wet gel was rapidly frozen and lyophilized. In Example 2, as shown in FIG. 2 (C), the wet gel was slowly frozen and lyophilized. Generation of wet gel, lyophilization, and generation of carbonized gel were performed in the same manner as in Example 1.

(Slow freezing of wet gel)
Using a vacuum freeze dryer (EYELA Tokyo Rika Kikai FDU-2100), the wet gel was placed in the maximum ice crystal formation zone for a long and slow freezing, and then rapidly -80 ° C. The wet gel was frozen by controlling the cooling temperature so that it was cooled down, followed by lyophilization.

  FIG. 16 is a diagram showing an optical microscope image (magnification: 10 times) of the polymer cryogel obtained in Example 2 of the present invention.

  As shown in FIG. 16, the polymer cryogel has pores in the range of 500 μm to 1000 μm. Although not shown, in the carbonized gel obtained by firing this polymer cryogel, pores having the same size as the polymer cryogel shown in FIG. 16 were confirmed.

[Example 3]
In Example 3, the quick freezing of the wet gel was performed by a method different from that in Example 1. Generation of wet gel, lyophilization, and generation of carbonized gel were performed in the same manner as in Example 1.

(Quick freezing of wet gel)
The wet gel was snap frozen so that the time for the wet gel to be placed in the maximum ice crystal formation zone was short and the freezing proceeded rapidly. Subsequently, it was freeze-dried in the same manner as in Example 1.

  FIG. 17 is a view showing a scanning electron microscope image (magnification: 500 times) of the carbonized gel obtained in the example of the present invention.

  As shown in FIG. 17, the carbonized gel has pores of about 10 μm.

[Example 4]
In Example 4, quick freezing of the wet gel was performed by a method different from that in Example 1. Generation of wet gel, lyophilization, and generation of carbonized gel were performed in the same manner as in Example 1.

(Quick freezing of wet gel)
As shown in FIG. 2 (B), a dispersion solution in which the wet gel is fragmented and dispersed in water is sprayed into liquid nitrogen, and the mist (droplet) containing the wet gel is 63K or more and 77K or less. It was cooled to a temperature of 5 ° C. to obtain a fine frozen body. Subsequently, this fine frozen body was freeze-dried in the same manner as in Example 1.

  FIG. 18 is a view showing a scanning electron microscope image (magnification: 8000 times) of the carbonized gel obtained in the example of the present invention.

  As shown in FIG. 18, the carbonized gel has pores of about 1 μm.

  As described above, according to the present invention, by controlling the time during which the organic wet gel passes through the maximum ice crystal formation zone, it has a macropore diameter ranging from 1 μm to 1000 μm, and the pore diameter is controlled. The produced porous carbon could be produced.

  The porous carbon according to the present invention having a pore diameter controlled and a macropore diameter in the range of 1 μm or more and 1000 μm or less can be used as a constituent material for a catalyst carrier, a gas diffusion layer, and an electrode. It can be suitably applied to electronic devices such as fuel cells, electric double layer capacitors, hybrid capacitors, and redox capacitors.

  As mentioned above, although this invention was described about embodiment, this invention is not limited to the above-mentioned embodiment, Various deformation | transformation are possible based on the technical idea of this invention.

  According to the present invention, it is possible to provide a method for producing porous carbon in which the pore diameter is controlled in the range of 1 μm or more and 1000 μm or less.

10a, 10b, 10c, 10d, 10e ... electrode, 12 ... current collector, 13 ... separator,
14 ... gasket, 20 ... anode, 22a, 22b ... catalyst electrode,
23 ... polymer electrolyte membrane, 24a, 24b ... gas diffusion layer, 25 ... fuel,
26a, 26b ... inlet, 27a, 27b ... passage, 28a, 28b ... outlet,
29a, 29b ... exhaust gas, 30 ... cathode, 35 ... air or oxygen, 40 ... membrane electrode assembly, 50 ... fuel supply unit, 60 ... air or oxygen supply unit, 70 ... external circuit

JP2008-184359 (paragraphs 0028-0029) JP2009-40646 (paragraphs 0005 to 0028)

Claims (20)

A first step in which an organic polymer hydrogel is produced by polymerizing a phenol compound and an aldehyde compound in the presence of a basic catalyst using water as a solvent;
A second step of freezing the organic polymer hydrogel;
A third step of lyophilizing the frozen organic polymer hydrogel;
Calcination of the lyophilized organic polymer hydrogel to produce porous carbon;
A method for producing porous carbon, comprising a step.   2. The method for producing porous carbon according to claim 1, wherein in the second step, the size of the pore diameter is controlled by the time during which the organic polymer hydrogel passes through the maximum ice crystal formation zone.   The manufacturing method of the porous carbon of Claim 2 which produces | generates the porous carbon whose said pore diameter is 1 micrometer or more and 1000 micrometers or less.   The method for producing porous carbon according to claim 2, wherein the pore diameter is controlled in a range of 1 µm to 100 µm by rapidly freezing the organic polymer hydrogel.   The method for producing porous carbon according to claim 2, wherein the pore diameter is controlled in a range of 10 µm or more and 30 µm or less by rapidly freezing the organic polymer hydrogel.   The method for producing porous carbon according to claim 4 or 5, wherein the organic polymer hydrogel is cooled to a temperature of 63K or higher and 77K or lower.   The method for producing porous carbon according to claim 4, wherein the pore diameter is controlled in a range of 1 μm to 2 μm by rapidly freezing the organic polymer hydrogel after dividing into small pieces.   The manufacturing method of the porous carbon of Claim 7 which sprays and rapidly freezes the dispersion solution which disperse | distributed the said organic polymer hydrogel in water.   The method for producing porous carbon according to claim 8, wherein the sprayed droplets of the dispersion solution are cooled to a temperature of 63K or higher and 77K or lower.   The method for producing porous carbon according to claim 2, wherein the pore diameter is controlled in a range of 100 µm or more and 1000 µm or less by slowly freezing the organic polymer hydrogel.   The method for producing porous carbon according to claim 2, wherein the pore diameter is controlled in a range of 500 µm or more and 1000 µm or less by slowly freezing the organic polymer hydrogel.   The method for producing porous carbon according to claim 11, wherein the organic polymer hydrogel is cooled to a temperature of 200 K or more and 273 K or less.   The method for producing porous carbon according to claim 12, wherein the organic polymer hydrogel is frozen in a refrigerator or a freezer.   The said 1st process WHEREIN: After dissolving the said phenol compound, the said aldehyde compound, and the said basic catalyst in the said solvent, it heats up to the temperature of 355 K or more and 365 K or less. Method for producing porous carbon.   The method for producing porous carbon according to claim 1, wherein the phenol compound is resorcinol, the aldehyde compound is formaldehyde, and the basic catalyst is sodium carbonate.   The said organic polymer hydrogel is a manufacturing method of the porous carbon of Claim 1 containing 95 mass% or more and 97 mass% or less of water.   2. The method for producing porous carbon according to claim 1, wherein in the fourth step, the freeze-dried organic polymer hydrogel is fired under an inert gas at atmospheric pressure.   The method for producing porous carbon according to claim 17, wherein the freeze-dried organic polymer hydrogel is baked at a temperature of 873 K or more and 1473 K or less.   An electronic device manufacturing method, wherein the porous carbon manufacturing method according to any one of claims 1 to 18 is applied, and at least one of a catalyst carrier, a gas diffusion layer, and an electrode is formed by the porous carbon. Method.   The method of manufacturing an electronic device according to claim 19, wherein the electronic device is configured as a fuel cell, an electric double layer capacitor, a hybrid capacitor, or a redox capacitor.