JP4945884B2 - Method for producing porous carbon material - Google Patents

Description

The present invention relates to a porous carbon material, and in particular, relates to a porous carbon material in which pores forming a porous structure are regularly arranged in three dimensions.

The porous carbon material, including some long rod-shaped single crystal obtained by crystallization over a long time of monodispersed colloidal silica aqueous solution, silica opal plate presence predominantly polycrystal in the phenolic resin is thermally cured, further heated up to 1000 ° C. by sintering, then, that known porous carbon material obtained by dissolving and removing the silica opal with hydrofluoric acid ( (Refer nonpatent literature 1) .

As a first treatment, an organic substance is introduced into the surface of the porous material and inside the pores, and this is heated to carbonize the organic substance. Then, as a second treatment, the organic substance is further introduced into the carbon and carbonized. by removing the quality materials, has a long period ordered structure in the range of 0.5nm to 100 nm, that is known to a porous carbon material having pores therein are formed (see Patent Document 1 ).
Further , the inventors of the present application have developed a polymer gel in which voids corresponding to inorganic particles are regularly arranged by impregnating inorganic particles, performing polymerization to obtain a polymer, removing the inorganic particles, and removing the inorganic particles. (Patent Document 2).

Anvar A. Zakhidov, et.al., Science, 282, 1998, 897. JP 2002-29860 A JP 2004-27195 A

However, all of the porous carbon materials have insufficient regularity of pores, and it is difficult to increase the area and thickness, and the physical properties of the obtained material are not always satisfactory. There was a problem.
An object of the present invention is to provide a porous material in which the arrangement of pores is controlled macroscopically so that more satisfactory physical properties can be obtained.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a nanoscale structure-controlled colloidal crystal produced by a specific method as a template. The invention has been completed.

That is, the present invention
(1) In a porous carbon material in which pores have three-dimensional regularity, the pores are arranged in an arrangement that constitutes a crystal structure macroscopically,
(2) In a porous carbon material having three-dimensional regularity of vacancies, the vacancies are macroscopically arranged on the material surface in a (1,1,1) plane orientation of a face-centered cubic lattice. With respect to the porous carbon material
(3) The porous carbon material according to (2), wherein the pores form a crystal structure,
(4) The porous carbon material according to any one of (1) to (3), wherein the pores are continuously arranged,
(5) The porous carbon material according to any one of (1) to (4), wherein the pores are arranged in a face-centered cubic structure,
(6) The porous carbon material according to any one of (1) to (5), wherein the size of the pores in the maximum length direction is in the range of 1 to 1000 nm,
(7) The porous carbon material according to any one of (1) to (5), wherein the size of the pores in the maximum length direction is in the range of 100 to 500 nm,
(8) the shape of the pores, the porous carbon material according to any of you being a spherical or substantially spherical (1) to (7),
(9) The porous carbon material according to any one of (1) to (8), wherein the porous carbon material is a non-graphitizable carbon material or a graphitized carbon material,
(10) The porous carbon material according to any one of (1) to (9), wherein the porous carbon material is glassy or crystalline.

(11) The compositions containing it was or polymerizable monomer, to obtain the monomer or polymer with a formulation composition impregnated in the composition in the colloidal crystal body in which insoluble step, not In a method for producing a porous carbon material, comprising a step of baking at 800 to 3000 ° C. in an active gas atmosphere, and a step of immersing the colloidal crystal in a soluble solvent to dissolve and remove the colloidal crystal. The colloidal crystal is deposited from the colloidal solution dropped on the substrate. The colloidal crystal is obtained by distilling off the solvent used in the solution. The colloidal solution is suction filtered to remove the solvent and deposit the colloidal crystal. A colloidal crystal obtained by immersing a substrate in a colloidal solution and pulling it up or evaporating the solvent used in the solution. The method for producing a porous carbon material characterized.

As described above, by using the method of the present invention, it has become possible to obtain a porous carbon material with a more controlled structure at the nanoscale on a macroscale. Porous carbon materials with nano-level structural regularity and porosity are used as electrode materials for capacitors, lithium ion batteries, fuel cells, etc., as various conductive materials, and as optical materials that selectively reflect specific wavelengths. It is useful and has high industrial utility value.

The porous carbon material of the present invention is characterized by being porous having a structure in which pores are arranged in a macroscopic crystal structure. The porous carbon material of the present invention is produced, for example, by polymerizing and firing nanoscale inorganic particles impregnated with a monomer or a solution containing a monomer, and then removing the inorganic particles. A void | hole represents the space | gap corresponding to each removed inorganic particle.

The pores may be voids closed with a porous carbon material as long as they have the above-mentioned regularity, but the continuous arrangement increases the surface area and expresses optical characteristics. Is preferable. If the holes are arranged to continue communicating, pores in the air gap was closed around a porous carbon material, or may be a void having a portion extending through an adjacent vacancy.

Regularity in arrangement of voids is not particularly limited as long as an arrangement constituting a crystal structure, for example, face-centered cubic, body-centered cubic, can be exemplified a simple cubic or the like, especially a face-centered cubic structure, That is, the close-packed structure is preferable from the viewpoint of optical characteristics and the like since the material has a large surface area and the pores are densely arranged. In particular, the crystal structure is preferably a single crystal structure.

Further, in the case of including holes of different sizes, it is possible to form a more complicated pattern. In the production method described above, will be sequences by Risora holes packing arrangement of the inorganic particles is determined, the structure capable sequences of the inorganic particles to be reflected in the regularity of the arrangement of voids become.

  Macro means to exclude a material that expresses its structure only in a very small area. For example, the reflection spectrum described below absorbs almost a single wavelength in any part of the obtained material. Means that the entire material is monochromatic.

The porous carbon material of the present invention is characterized by having a structure in which vacancies are arranged macroscopically in a (1,1,1) plane orientation of a face-centered cubic lattice on the surface of the carbon material. This means that, for example, even when the porous carbon material is cut on an arbitrary surface, the surface always has the above orientation.

The shape of the pores is not particularly limited. For example, in the manufacturing method described above, the shape is determined to some extent by the shape of the inorganic particles used, but the mechanical strength of the porous carbon material, the inorganic particles on the nanoscale considering that control the shape, preferably a spherical or substantially spherical.

  The size of the pores in the maximum length direction is not particularly limited, but is preferably in the range of 1 to 1000 nm. If it is 1 nm or less, the void is too small to show a significant difference from the bulk carbon material, and if it is 1000 nm or more, the void is too large as a whole, which may reduce the mechanical strength. In consideration of optical characteristics, the surface area of the polymer, etc., the size of the pores in the maximum length direction is preferably in the range of 100 to 500 nm.

The method for producing the porous carbon material of the present invention is not particularly limited, but considering the ease of the production method, the ease of control of the fine structure, etc., JP-A-9-67405 or Applying the method described in Japanese Patent Application Laid-Open No. 2001-2131992, a polymerizable monomer or a composition containing the same is used as a particulate material insoluble in the monomer or composition and soluble in other solvents the blend composition obtained by mixing colloidal crystal used as, first, the monomer is polymerized, further calcined by raising the temperature to about 800 to 3000 ° C., then the colloidal crystal is immersed in a soluble solution colloidal crystals It is preferable to manufacture by dissolving and removing. In this case , the colloidal crystal represents a state in which colloidal particles gather to form a crystal structure.

As a method for obtaining a colloidal crystal, specifically, (i) a method in which an electric field is applied to a colloidal solution and then the solvent is removed; (ii) a relatively dilute solution having a solid content concentration of 1 to 5% by weight , two flat substrates with an interval of several tens of mu m by opposed to dipping the substrate lower, the colloidal solution is increased to between the substrates by capillarity, by the solvent is evaporated off, colloidal between substrates Examples include a method for precipitating crystals, (iii) a method in which a dispersed colloidal solution is allowed to stand, a colloidal particle is naturally precipitated and deposited, and then a solvent is removed, and (iv) a known method such as an advection accumulation method. be able to.

  As another method for producing a colloidal crystal, a method in which a colloidal solution is dropped on a substrate and the solvent used in the colloidal solution is distilled off can be preferably exemplified. Although the solvent can be distilled off at room temperature, it is preferably heated and dried at a temperature equal to or higher than the boiling point of the solvent used. In addition, this method may be any method such as dropping a colloidal solution onto a substrate and then heating the substrate to distill off the solvent, or dropping the colloidal solution onto a preheated substrate and distilling off the solvent. It can be carried out. Further, the substrate may be rotated when or after the colloidal solution is dropped.

Colloids obtained by repeating colloidal solution dripping and solvent evaporation operations, adjusting the concentration of colloidal solution, adjusting the amount of colloidal solution to be dripped, and any combination of the above. The film thickness and area of the crystal can be freely controlled. In particular, since it is possible to easily increase the area or volume while maintaining regularity, the porous carbon material of the present invention can be increased in area and volume in accordance with it.

For example, according to the present method, since a colloidal solution having a solid content concentration of 10% by weight or more can be used, a colloidal crystal having a considerable film thickness can be formed on the substrate by a single dropping, By repeating the drying, the film thickness can be freely controlled. Furthermore, in this method, for example, by using a monodispersed colloid solution, the obtained colloidal crystal can be made into a colloidal crystal having a single crystal structure. Porous carbon materials obtained using colloidal single crystals have regularity and continuity in the arrangement of pores in the macro, there is no variation in the wavelength of reflected light, and the wavelength of selective reflected light is unified as a whole. can do.

Further, as another method, by vacuum suction or the like solution using a suction funnel containing colloidal particles, the solution more to the suction removal filter paper on the suction funnel, or a method of depositing colloidal particles on the filter cloth It can be illustrated preferably. Also in the above method, for example, a colloidal single crystal can be obtained by using a monodispersed colloidal solution.

  The concentration of the solution used for suction filtration can be freely selected depending on the volume of the colloidal crystal to be obtained in one operation. Further, once all the solvent is removed by suction, a solution is added again and the same operation is repeated to obtain a colloidal crystal having an arbitrary volume. By using this method, it is possible to increase the area and increase the volume while maintaining regularity as before.

  The method of sucking the solvent is not particularly limited, and examples thereof include a method of sucking with aspirator or pump. The speed of suction is not particularly limited, but specifically, a speed at which the solution interface in the funnel is constantly lowered at a reduced pressure of about 40 mmHg can be preferably exemplified.

  As another method, a method of immersing a substrate in a colloidal solution and pulling it up or evaporating a solvent used in the solution can be preferably exemplified. Also in this method, a colloidal crystal having an arbitrary area and volume can be obtained by adjusting the concentration of the colloid solution to be used or repeating the same operation. The pulling speed is not particularly limited, but it is preferably pulled at a slow speed because crystals grow at the interface of the solution with the atmosphere. Also, the speed of evaporating the solution is not particularly limited, but it is preferably slower for the same reason. Moreover, a colloidal single crystal can be obtained by using a monodispersed colloidal solution.

Although the property of the substrate surface to be used is not particularly limited, a substrate having a smooth surface is preferable in consideration of the optical characteristics of the porous carbon material obtained using the colloidal crystal.

  The colloidal particles, which are particulate materials used in the production of the porous carbon material of the present invention, preferably have a spherical or substantially spherical shape such as a true sphere. For example, a fluorine compound solution such as hydrofluoric acid, Inorganic compound particles that can be dissolved in an alkaline solution or an acidic solution can be preferably used.

Specific examples of the inorganic compound include alkaline earth metal carbonates, silicates, metal oxides, metal hydroxides, other metal silicates, and other metal carbonates. the Examples of the alkaline earth metal carbonate, calcium carbonate, barium carbonate, or the like carbonate Maguneumu is, as the alkaline earth metal silicate, calcium silicate, barium silicate, magnesium silicate and the like, also alkaline earth metal the salt of phosphoric acid, calcium phosphate, barium phosphate, magnesium phosphate and the like. Further, as the metal oxide, silica, titanium oxide, iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide, aluminum oxide and the like, metal hydroxides, iron hydroxide, nickel hydroxide, hydroxide Aluminum, calcium hydroxide, chromium hydroxide and the like can be exemplified. Then, as the other metal silicates, zinc silicate, aluminum silicate and the like. Examples of the other metal carbonates, zinc carbonate, basic copper carbonate and the like can be exemplified, respectively. Examples of natural products include shirasu balloon and pearlite.

  The size in the maximum length direction of these colloidal particles is preferably in the range of 1 to 1000 nm, and more preferably in the range of 100 to 500 nm.

The polymer that can be converted into the porous carbon material of the present invention is not particularly limited as long as it is a polymer that can be converted into a carbon material by high-temperature firing, and specifically, a furfuryl alcohol resin, a phenol-aldehyde resin. And styrene-divinylbenzene copolymer, furfuryl alcohol-phenol resin, and the like. Becomes I Risumi material cost Gaga lath-shaped non-graphitizable carbon or graphitized carbon to selecting the sintering temperature, the polymer is preferable.

  In order to produce a polymer before firing in the presence of a regularly arranged colloidal single crystal or other particulate material, the monomer concentration is 0.1% to 99.9% by weight, and crosslinking is added as necessary. The agent concentration may be 0.001 wt% to 50 wt%. The reaction conditions such as the initiator concentration and the polymerization method may be selected according to the monomer. For example, the catalyst, the polymerization initiator, the monomer, the crosslinking agent, etc. are dissolved in an organic solvent substituted with nitrogen. The solution can be impregnated with a colloidal crystal that is regularly arranged and then impregnated with the solution, and then polymerized by heating to an appropriate temperature or irradiating with light.

  The above-mentioned various polymers can be obtained by a known solution such as radical polymerization, acid polycondensation, etc., bulk, emulsion, reverse phase suspension polymerization, etc., at a polymerization temperature of 0 to 100 ° C. and a polymerization time of 10 minutes to 48 hours. it can.

In order to dissolve and remove the colloidal crystal from the composite of the colloidal crystal and the polymer, for example, when the colloidal crystal is an inorganic compound, an acidic solution, an alkaline solution, an acidic solution, or the like of a fluorine compound can be used. For example, silica colloidal crystal body, in the case of shirasu balloon or silicate, aqueous hydrofluoric acid, ammonium fluoride, calcium fluoride, a complex compound in an alkaline solution such as an acid solution or sodium hydroxide, etc. sodium fluoride Just immerse it. The solution may be at least 4 times the amount of fluorine element relative to the silicon element of the composite, but the concentration is preferably at least 10% by weight. The alkaline solution is not particularly limited as long as it has a pH of 11 or more. Particulate compound metal oxides, if the metal hydroxide, it is only immersing the composite compound in an acidic solution such as hydrochloric acid. The acidic solution is not particularly limited as long as it has a pH of 3 or less.

  The dissolution and removal of the colloidal crystal may be performed before or after the obtained polymer is sintered, and can be performed in an inert atmosphere at a temperature in the range of 800 to 3000 ° C. The temperature increase rate up to the firing temperature is not particularly limited as long as the carbon structure is not collapsed by local heating.

  The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

A monodispersed silica colloid suspension aqueous solution ( prepared aqueous solution having a solid content concentration of 3% using monodispersed silica spherical fine particles KE-P30 manufactured by Nippon Shokubai Co., Ltd., colloidal particle diameter: 280 nm) was filtered through a filter cloth (a polycarbonate membrane manufactured by Whatman). A SPC filter holder (manufactured by Shibata Kagaku) with a diameter of 30 mm with a filter and filter pore size: 100 nm) was put in, and suctioned under reduced pressure (about 40 mmHg) using an aspirator to obtain a silica thin film on the filter cloth. After the filter cloth was peeled off, it was sintered in air at 1000 ° C. for 2 hours to obtain a silica colloid single crystal film.
A mixture of 10.0 g of furfuryl alcohol and 0.0500 g of oxalic acid hexahydrate (both manufactured by Wako Pure Chemical Industries, Ltd.) was dropped onto a silica colloid single crystal film on a Teflon (registered trademark) sheet, and silica colloid The excess mixture overflowing on the crystals was gently wiped off and polymerized in air at 80 ° C. for 48 hours. The obtained silica-polymer resin composite was subjected to moisture removal and polymer re-curing process at 200 ° C. for 1 hour in an argon atmosphere in a tubular furnace, and then heated to 1000 ° C. at 5 ° C./min. The silica-carbon composite was obtained by firing at 1000 ° C. for 1 hour and naturally cooling.

Further, it was immersed in a 48% hydrofluoric acid solution at room temperature for 1 week to dissolve the silica colloidal crystals. The hydrofluoric acid solution was changed every other day. Thereafter , washing with pure water was repeated until neutrality, and a porous carbon material 1 was obtained.

  A scanning electron microscope (SEM) photograph of the surface of the porous carbon material obtained as described above is shown in FIG. As shown in FIG. 1B, the holes are spherical with a diameter of 280 nm, and the adjacent holes are connected with through holes of about 40 nm, and the holes are arranged in a face-centered cubic structure. It was found that the surface of the material was arranged with (1,1,1) plane orientation.

  The porous carbon material was placed in a dark place, irradiated with white light at a viewing angle of 0 °, and the wavelength of reflected light was measured. The result is shown in FIG. The obtained reflection spectrum shows unimodal absorption only in the vicinity of 450 nm, indicating that the pores are regularly arranged even inside the material.

A monodispersed silica colloid suspension aqueous solution (manufactured by Nippon Shokubai Co., Ltd., monodispersed silica colloid suspension KE-W30, solid content concentration 15 wt%, colloid particle size: 280 nm) was made from Teflon (registered trademark) 3 cm × 3 cm × 0.5 cm. the solvent was evaporated at poured into a container having a volume 100 ° C., to obtain a silica colloid crystals.

A mixture of 10.0 g of furfuryl alcohol and 0.0500 g of oxalic acid hexahydrate (both manufactured by Wako Pure Chemical Industries, Ltd.) is injected into the silica colloidal crystal in the container, and the excess mixture overflowing on the crystal is lightly removed. It was wiped off and polymerized in the air at 80 ° C. for 48 hours. The obtained silica-polymer resin composite is peeled off from the Teflon (registered trademark) plate, fired in a tube furnace in the same manner as in Example 1, and the silica is removed and washed with a 48% hydrofluoric acid solution. Thus, a porous carbon material 2 was obtained. The porous carbon material 2 was also subjected to SEM observation and reflected light spectrum measurement in the same manner as in Example 1. As a result, it was found that the porous carbon material 2 had almost the same structure as the porous carbon material 1.

  After obtaining the silica-polymer resin composite, the porous carbon material 3 was obtained in the same manner as in Example 1 except that the silica colloid crystal was dissolved using a hydrofluoric acid solution and then fired. When SEM observation and reflected light spectrum measurement of the obtained porous carbon material 3 were performed in the same manner as in Example 1, it was found that the porous carbon material 3 had the same structure as the porous carbon material 1.

Examples other than using monodispersed aqueous silica colloid suspensions with different particle sizes ( preparing an aqueous solution having a solid content concentration of 3% using monodispersed silica spherical fine particles KE-P100 manufactured by Nippon Shokubai Co., Ltd., colloid particle size: 1000 nm) 1 was performed to obtain a porous carbon material 4.
The surface areas of the porous carbon material 1 and the porous carbon material 4 were measured by the BET method. For comparison, powdered carbon produced under the same conditions without using silica colloidal crystals was also measured. The pore volume was also determined from the pore size distribution obtained at the same time. The results are summarized in Table 1.

(A) The electron microscope (SEM) photograph of the surface of the porous carbon material obtained in Example 1 is shown. (B) The enlarged view of (a) is shown.

It is a figure which shows each reflection spectrum of (a) silica colloid crystal obtained in Example 1, (b) silica-polymer resin composite, (c) silica-carbon composite, and (d) porous carbon material. .

Claims (2)

A step of impregnating a polymerizable monomer or a composition containing the same into a colloidal crystal, followed by polymerization to obtain a polymer, a step of baking at 800 to 3000 ° C. in an inert gas atmosphere, and the colloidal crystal body consists step of dissolving and removing the colloidal crystal body was immersed in soluble solvents, however, the step of dissolving and removing the colloidal crystal body is rather good before or after step that forms shrink the resulting polymer ,
Porous to obtain a thin film of colloidal crystals by depositing colloidal particles on the filter paper or filter cloth of the suction funnel by sucking and removing the solution containing the colloidal particles under reduced pressure using a suction funnel A method for producing a carbon material. The polymer, furfuryl alcohol resins, phenol - aldehyde resins, styrene - divinylbenzene copolymer, or furfuryl alcohol - a phenolic resin, wherein the colloidal particles are alkaline earth metal carbonates or silicates, metal oxides, metal hydroxides, metallic silicates or, method for manufacturing the porous carbon material according to claim 1 comprising a metallic carbonate.