JP5915978B2 - Metal-supported carbon material and method for producing the same - Google Patents

Description

  The present invention relates to a metal-supported carbon material and a method for producing the same. More specifically, the present invention relates to a metal-supported carbon material suitable for application to a hydrogen storage material for a fuel cell or an electrode catalyst, and a method for producing the same.

  The storage of a large amount of hydrogen is an indispensable technology for the practical application of fuel cell vehicles, and research on hydrogen storage materials such as hydrogen storage alloys, chemical hydrides, and adsorbent materials has been actively conducted. Hydrogen storage alloys and chemical hydrides have a large storage capacity compared to adsorption materials and have a hydrogen storage capacity of more than 5% by weight. There are problems such as being short. On the other hand, examples of the adsorption material include carbon materials such as activated carbon and carbon nanotubes. Adsorption-based materials do not require heating during the hydrogen storage / release process in order to use physical adsorption, but have a problem that the storage amount is small compared to hydrogen storage alloys and chemical hydrides. Therefore, in recent years, a hydrogen storage method using spillover in addition to physical adsorption has attracted attention.

  Spillover is a phenomenon in which, when a metal such as platinum is supported on a solid surface, hydrogen molecules in the gas phase are dissociated into hydrogen atoms on the metal surface by the action of the metal and flow out onto the solid surface. Since the outflowing hydrogen atoms are adsorbed on the solid surface, it is considered that the hydrogen storage capacity can be improved in combination with physical adsorption in which hydrogen is adsorbed as molecules. For example, Non-Patent Document 1 reports that when platinum nanoparticles are supported on activated carbon with a high surface area, the hydrogen storage capacity at room temperature is greatly increased compared to that before support, which is in addition to physical adsorption. This is due to the effect of spillover.

J. et al. Phys. Chem. C, 111 (2007) 11086.

  However, a hydrogen storage material capable of storing a larger amount of hydrogen is required for the practical application of fuel cell vehicles. Therefore, in order to further improve the hydrogen storage capacity, it is necessary to promote the adsorption of atomic hydrogen by the spillover phenomenon in addition to the physical adsorption, but the mechanism of the spillover has not been elucidated yet, and the spillover phenomenon It is difficult to increase the amount of hydrogen occluded by the adsorption of atomic hydrogen.

  Therefore, an object of the present invention is to provide a metal-supported carbon material having improved hydrogen storage characteristics due to spillover.

  In view of the above problems, the present inventors have made extensive studies. In the process, the inventors found that spillover activity can be improved by controlling the form of the metal supported on the carbon material, and completed the present invention.

  That is, the present invention is a metal-supported carbon material in which metal particles are supported on a carbon material having pores, and the average particle size of the supported metal particles is 3 nm or less, and 50% of the supported metal particles. This is a metal-supported carbon material having a particle size of 1 nm or less.

  According to the present invention, a high spillover effect can be obtained, and a hydrogen storage material with improved hydrogen storage capacity can be obtained.

It is a schematic diagram showing the metal carrying | support carbon material in which the metal particle was introduce | transduced. It is a schematic diagram showing a microporous carbon material. 2 is a TEM photograph of a sample prepared in Reference Example 1. 2 is a TEM photograph of a sample prepared in Example 1. 2 is a TEM photograph of a sample prepared in Example 2. 4 is a TEM photograph of a sample prepared in Example 3. 4 is a TEM photograph of a sample prepared in Comparative Example 1. The XRD pattern measured in the air atmosphere before and after heat treatment and hydrogen treatment of the sample prepared in Example 1 and the XRD pattern measured in the air atmosphere before and after hydrogen treatment of the sample prepared in Example 2 are shown. FIG. It is a XRD pattern of the sample prepared in Reference Example 1 and Comparative Example 1. It is a TEM photograph after heat-processing at 200 degreeC of the sample prepared in Example 1. FIG. 2 is a TEM photograph after heat treatment at 300 ° C. of the sample prepared in Example 1. FIG. It is the TEM photograph measured after hydrogen-treating the sample prepared in Example 1 at 25 degreeC and 50 degreeC. It is the TEM photograph measured after hydrogen-treating the sample prepared in Example 1 at 25 degreeC, 50 degreeC, and 70 degreeC. It is the TEM photograph measured after hydrogen-treating the sample prepared in Example 2 at 25 degreeC and 50 degreeC. It is the TEM photograph measured after hydrogen-treating the sample prepared in Example 2 at 25 degreeC, 50 degreeC, and 70 degreeC. It is a figure which shows the XAFS measurement result of the sample prepared in Example 1. FIG. It is a figure which shows the XAFS measurement result of the sample prepared in Example 2. FIG. It is a figure which shows the XAFS measurement result of the sample prepared by the comparative example 1. For the samples prepared in Example 1, Example 2, and Comparative Example 1, EXAFS of samples before hydrogen treatment (room temperature, in He) and after hydrogen treatment (room temperature, 50 ° C., 70 ° C., 100 ° C.), respectively (A) plotting the average coordination number of platinum determined from the above, and the average coordination number of carbon atoms or nitrogen atoms around the platinum atom, (b) plotting the interatomic distance, and average coordination in platinum particles It is the figure (c) which plotted the relationship between an order and an average particle diameter. 6 is a diagram showing a hydrogen adsorption / desorption isotherm of a sample manufactured in Example 2. FIG. It is a figure showing the hydrogen adsorption-desorption isotherm before the hydrogen treatment of the sample manufactured in Example 1, and after the hydrogen treatment. It is a figure showing the hydrogen adsorption-desorption isotherm before the hydrogen treatment of the sample manufactured in Example 2, and after the hydrogen treatment. It is a figure showing the high pressure hydrogen storage characteristic of the sample prepared in (a) Reference example 1, (b) Comparative example 1, and (c) Example 3. 2 is a diagram showing hydrogen adsorption / desorption isotherms of samples manufactured in Example 1, Example 2, and Comparative Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

<Metal-supported carbon material>
One embodiment of the present invention is a metal-supported carbon material in which metal particles are supported on a carbon material having pores, and the supported metal particles have an average particle size of 3 nm or less, and the supported metal particles Is a metal-supported carbon material having a particle diameter of 50% or more of 1 nm or less.

  As shown in FIG. 1, the metal-supported carbon material according to the present embodiment has metal particles supported on at least a part of the surface of the carbon material. Hydrogen molecules dissociate in contact with metal particles, and the dissociated hydrogen atoms are trapped in the carbon material.

  In the metal-supported carbon material according to the present embodiment, the average particle size of the supported metal particles is 3 nm or less, and 50% or more of the supported metal particles are particles having a particle size of 1 nm or less. Here, for example, when the metal is Pt, the number of Pt particles contained in particles having an average particle diameter of 3 nm is about 612, and the number of Pt particles contained in particles having an average particle diameter of 1 nm is about 10. When the average particle size of the metal particles is larger than 3 nm, or when the number of metal particles having a particle size of 1 nm or less is less than 50% of the total number of particles, sufficient spillover activity cannot be obtained. Preferably, the average particle diameter of the metal particles is 1 nm or less. The lower limit of the average particle diameter is not particularly limited, but is, for example, 0.28 nm from the viewpoint of obtaining high spillover activity. More preferably, the number of particles having a particle size of 1 nm or less is 70% or more of the total number of particles, more preferably 90% or more, still more preferably 95% or more, and particularly preferably 99% or more. . The particle size of the metal particles can be measured using CO adsorption or an ultra-high performance transmission electron microscope.

  In the present specification, the particle diameter means the maximum distance among the distances between any two points on the outline of the particle (observation surface) observed using an observation means such as a transmission electron microscope. As the value of the average particle diameter, a value calculated as an average value of particle diameters of particles observed in several to several tens of fields using an observation means such as a transmission electron microscope is used.

  Preferably, the metal particles have an average coordination number of metal atoms determined from XAFS of 5.5 or less and an average particle size of 1.2 nm or less. If it is the said range, the effect of this invention can be acquired more notably. The average coordination number of the metal atoms is more preferably 4.1 or less, and even more preferably 4.0 or less. The average particle diameter of the metal particles is more preferably 0.70 nm or less, and further preferably 0.65 nm or less. In addition, the average ligand number of a metal atom and the average particle diameter of a metal particle can be calculated | required by the method as described in the below-mentioned Example.

  In the metal-supported carbon material of the present embodiment, the metal particles may be supported on at least a part of the surface of the carbon material. The metal particles may be introduced into the pores of the carbon material.

  The metal to carry | support can use a 8-10 group metal from a viewpoint of providing functionality. In addition, the metal is not limited to a single substance, and two or more kinds of metals may be supported. Among them, when used as a hydrogen storage material, Pt, Pd, Ir, Rh, Co, Ni, Ru, and Fe are preferably used, Pt, Pd, and Ni are more preferably used, and Pt is particularly preferable.

  The metal is supported within a concentration range of preferably 0.01 to 50 wt%, more preferably 0.01 to 15 wt% with respect to the material for supporting the metal. Here, the material for supporting the metal is a carbon material, or when a functional group or a ligand is introduced into the carbon material, a carbon material into which the functional group or a ligand is introduced. sell. If the supported metal is 0.01 wt% or more, the metal function can be sufficiently obtained. On the other hand, when the supported metal is 50 wt% or less, the pore function of the carbon material can be maintained and a high BET surface area can be obtained.

  The carbon material is not particularly limited as long as it has pores, and carbon particles such as carbon black, activated carbon, coke, natural graphite, and artificial graphite can be used. In order to increase the hydrogen storage capacity, a microporous carbon material such as zeolite template carbon (ZTC) can be preferably used. ZTC has a structure in which spherical, thin graphene sheets are regularly connected in a three-dimensional manner and has an ultra-high surface area, and thus has excellent hydrogen storage characteristics.

  FIG. 2 schematically shows an example of zeolite-templated carbon as a microporous carbon material. Zeolite template carbon 2 is zeolite carbon 2 obtained using zeolite 1 as a template. More specifically, the zeolite-templated carbon 2 is produced by first introducing an organic compound as a carbon source into the micropores 1a of the zeolite 1 shown in FIG. A composite 3 of the indicated zeolite 1 and zeolite carbon 2 is prepared. Thereafter, only zeolite 1 is removed to obtain zeolite-templated carbon 2 (FIG. 2 (c)). The zeolite-templated carbon 2 has a three-dimensional long-period regular structure reflecting the structural characteristics of the zeolite 1 used as a template, and micropores 2a inside.

  Zeolite template carbon 2 is a porous carbon material that reflects the structural characteristics of zeolite 1 having a specific three-dimensional regular structure, which is a template material used in the production thereof. The zeolite template carbon 2 has a structure in which pores (micropores 2a) having a diameter in the range of 0.1 to 2 nm are connected in a network. Specifically, the zeolite-templated carbon 2 has a three-dimensional long-period regular structure in the range of 0.5 to 100 nm and has micropores 2a. More specifically, the zeolite-templated carbon 2 has a distance between carbon chains constituting the three-dimensional long-period ordered structure, preferably 0.5 to 100 nm, more preferably 0.7 to 50 nm. More preferably, it is 0.7-2 nm. Thus, the zeolite template carbon 2 is a carbon material having a structure in which the distance between the carbon chains is regularly repeated over a long period three-dimensionally at an arbitrary interval. In IUPAC (International Genuine and Applied Chemistry Union), pores with a diameter of 2 nm or less are micropores, pores with a diameter of 2-50 nm are mesopores, and pores with a diameter of 50 nm or more are macro. It is defined as a pore. Substances having micropores are collectively referred to as a microporous material.

  In the present embodiment, the carbon material may not be chemically modified, or may be an edge-modified carbon material in which a functional group is introduced into at least a part of the edge portion. When the functional group is introduced, the functional group is introduced into at least a part of the edge portion of the carbon material, for example, and a functional group having an amidine structure can be used.

  In the present specification, the amidine structure is a structure in which one nitrogen atom is bonded to one carbon atom through a double bond, and one nitrogen atom is bonded through a single bond. Since the amidine structure is a strong base and exhibits nucleophilicity, as described later, a phosphorus ligand can be further introduced into the amidine structure portion to introduce a metal complex. As a functional group which has an amidine structure used for this invention, the functional group represented by following Chemical formula 1 is mentioned, for example.

In the formula, R ^a , R ^b and R ^c are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms or a substituted or unsubstituted cycloalkyl group having 3 to 6 carbon atoms, R ^a and R ^b may combine to form a ring, or R ^b and R ^c may combine to form a ring.

The alkyl group may be linear or branched. The alkyl group or cycloalkyl group may be substituted or unsubstituted. Although carbon number which an alkyl group has is not specifically limited, Preferably it is 1-10 pieces, More preferably, it is 1-5 pieces. Although carbon number which a cycloalkyl group has is not specifically limited, Preferably it is 3-6. The substituent of the alkyl group or cycloalkyl group is not particularly limited, and examples thereof include a hydroxyl group, a carboxyl group, an amino group, a cyano group, and a halogen atom. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group. Octyl group, nonyl group, decyl group, and the like. Examples of the cycloalkyl group include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group. Alkyl groups or cycloalkyl groups other than these may be used. When R ^a and R ^b are combined to form a ring, or when R ^b and R ^c are combined to form a ring, the ring is preferably a 5- to 6-membered ring, more preferably It is a 5-membered ring.

  Among these, a functional group represented by the following chemical formula can be preferably used.

  Since the carbon material into which the functional group having the amidine structure is introduced has hydrophilicity, it is useful as an adsorbent for polar gases such as water vapor, acid gas, oxygen-containing hydrocarbon vapor and the like. Further, when applied as an electrode of an electric double layer capacitor (EDLC), an improvement in performance can be expected. In general, the electrolyte solution of EDLC has a large polarity, and considering the affinity (wetting property) with the electrode surface, an electrode exhibiting hydrophilicity is desired. Carbon materials, including activated carbon and microporous carbon materials, are highly hydrophobic and modify the affinity (wetting properties) when applied to capacitors and the like. For this reason, secondary surface modification treatment that does not involve the direct performance of EDLC may be performed. On the other hand, the carbon material into which the functional group having the amidine structure is introduced does not need to be subjected to secondary surface modification treatment and can be used as it is. For this reason, a better effect can be expected. In addition, in an adsorption heat pump that uses adsorption / desorption of water vapor, since performance can be significantly improved as compared with zeolite currently used as an adsorbent, performance improvement such as downsizing of the apparatus can be expected.

The carbon material or the metal-supported carbon material of the present embodiment preferably has a BET surface area of 1500 m ² / g or more. For example, a carbon material using zeolite-templated carbon or a metal-supported carbon material has a large BET surface area because it has a three-dimensional long-period ordered structure and micropores. In general, for application to adsorbents, a large BET surface area is preferred. The presence of micropores is also considered important, although it is affected by the size of molecules to be adsorbed. On the other hand, it is considered that mesopores are not very effective when applied to the aforementioned uses. For this reason, in order to express a desired high function, it is important that a relatively large number of micropores are present, and it is considered that it is better to have as few mesopores as possible. As a guide, the BET surface area is preferably 1500 m ² / g or more. Moreover, it is more preferable that it is 2000 m < ² > / g or more, Furthermore, it is preferable that it is 2500 m < ² > / g or more. Even more preferably, the BET surface area is 3000 m ² / g or more, particularly preferably 3500 m ² / g or more. When the BET surface area is 1500 m ³ / g or more, a high hydrogen storage capacity can be obtained. The BET surface area can be determined by nitrogen adsorption / desorption measurement.

In the carbon material or the metal-supported carbon material according to the present embodiment, the volume occupied by the micropores 2a is, for example, 0.6 cm ³ / g or more, preferably 0.8 cm ³ / g or more, and 1.0 cm. More preferably, it is ³ / g or more. The volume occupied by the micropores 2a is still more preferably 1.2 cm ³ / g or more, and particularly preferably 1.5 cm ³ / g or more. When the volume occupied by the micropores is 0.6 cm ³ / g or more, particularly 1.0 cm ³ / g or more, sufficient hydrogen storage performance can be obtained. The volume occupied by the micropores can be determined by nitrogen adsorption / desorption measurement.

  The carbon material or the metal-supported carbon material of the present embodiment has a higher adsorptive power as the two-dimensional stacking regularity is smaller as a structural feature. For example, when powder X-ray diffraction measurement is performed, it is preferable that the obtained X-ray diffraction pattern has as few diffraction peaks as possible that usually appear in the vicinity of 26 ° indicating two-dimensional stacking regularity. The presence of diffraction peaks appearing near 26 ° means an increase in the nonporous carbon layer and a decrease in the BET surface area.

  The metal-supported carbon material according to this embodiment can occlude and release hydrogen in the range of −40 ° C. to 150 ° C. Conventionally, a carbon material that is not metal-supported has a case where the hydrogen occlusion amount decreases as the temperature rises. However, the metal-supported carbon material according to the present embodiment improves the occlusion ability as the temperature increases. Moreover, compared with the case where a particulate metal having an average particle diameter of 2 to 3 nm is supported, dissociative adsorption of hydrogen molecules is promoted, and the hydrogen storage ability can be improved. Therefore, when the metal-supported carbon material is used as a hydrogen storage material, highly efficient storage and release of hydrogen becomes possible.

  In addition, the metal-supported carbon material according to the present embodiment has a hydrogen storage amount (a value obtained by subtracting the hydrogen storage amount by physical adsorption from the total hydrogen storage amount) due to the spillover effect when high-pressure hydrogen absorption / desorption measurement up to 10 MPa is performed. For example, it is 0.1% or more with respect to the weight of the carbon material, and preferably 0.2% or more.

<Method for producing metal-supported carbon material>
The metal-supported carbon material according to the present embodiment includes a step of preparing a carbon material having pores, a step of introducing a metal complex into the carbon material, a heat treatment of the carbon material into which the metal complex has been introduced, or hydrogen. And reducing the metal complex by contacting to obtain a metal-supported carbon material on which metal particles are supported.

In general, as a method for introducing nano-sized metal particles into a carbon material, a metal complex such as Pt (NO ₂ ) ₂ (NH ₃ ) ₂ or H ₂ PtCl ₆ is used using a reducing agent such as sodium borohydride. A reduction method is used. However, with such a method, it is not easy to produce metal particles having an average particle size of 3 nm or less while controlling the particle size.

  On the other hand, according to the method of the present embodiment, the metal is first supported on the surface of the carbon material at the atomic level by introducing the metal into the carbon material as a complex. Thereafter, the metal atoms are desorbed from the ligand by heat treatment or contact with hydrogen. The detached metal atoms can form a nanocluster having several atoms to several tens of atoms by gathering (sintering) a plurality of atoms. Therefore, it is possible to introduce the metal into the carbon material with high dispersion, and to suppress excessive aggregation of metal atoms as compared with the case of reducing the metal using a reducing agent such as sodium borohydride. it can. Moreover, there is an advantage that complicated experimental operation can be avoided.

(Step of preparing a carbon material having pores)
There are no particular restrictions on the route for obtaining the carbon material (carbon material precursor) as a raw material. Commercially available products may be used or prepared by themselves. Hereinafter, the case where a microporous carbon material such as zeolite-templated carbon is used will be described.

  First, in order to obtain a microporous carbon material having the above-mentioned structural characteristics, a porous material having a structure in which pores are connected inside the structure and connected in a mesh form is used as a template. Then, an organic compound is introduced into the surface of the porous material and inside the micropores under heating conditions, and the organic compound is carbonized by heating to deposit carbon on the porous material. Carbonization / deposition of an organic compound is performed by, for example, a chemical vapor deposition (CVD) method. Next, the porous material which is a template is removed. By this method, a microporous carbon material having micropores can be easily produced.

  The porous material used as the template needs to be able to introduce an organic compound into the micropores, to keep the original structure stable during the CVD method, and to be separable from the generated microporous carbon material. For this reason, for example, a material that is excellent in heat resistance, such as a porous oxide, and is soluble in an acid or alkali is desirable. Further, as already described, the microporous carbon material is synthesized with the form of the template transferred. For this reason, it is desirable that the porous material used as a template is a material in which crystals (structures) are sufficiently developed and the structure and composition are uniform in particle size. Considering the material properties that the porous material should have and the physical properties of the resulting microporous carbon material, it is preferable to use zeolite as the porous material. Zeolite is an aluminosilicate in which a part of silicon (Si) having a silica structure is replaced with aluminum (Al), and the skeleton itself has a negative charge, so that cations are distributed in the structure. Zeolite has a variety of crystal structures depending on the Si / Al molar ratio, the type and amount of cation, and the number of water molecules hydrated to the cation, for example, a structure in which pores are two-dimensionally connected or three-dimensional. It is a porous material having pores of various sizes, such as a connected structure. Typical zeolites include those having a void structure such as a cage or a super cage. Among zeolites, it is desirable to use YAU zeolite among FAU zeolite and FAU zeolite. For removing the porous material, any method may be used as long as the produced microporous carbon material can be separated. For example, zeolite can be dissolved with an acid, and can be easily dissolved by using, for example, hydrochloric acid or hydrofluoric acid.

  The CVD method used for carbonizing an organic compound to deposit carbon is an industrial method for producing a thin film (for example, a thin film made of carbon) made of a specific element or element composition on a substrate such as a mold. Normally, by applying energy to the gas containing the raw material by heat or light, or by making it into plasma at a high frequency, the raw material becomes radical due to chemical reaction or thermal decomposition and becomes highly reactive. This is a technology that uses adsorption and deposition. Distinguishing materials from which the source material is deposited by raising the temperature is differentiated from the thermal CVD method, irradiating light to promote chemical reaction and thermal decomposition, the photo CVD method, and the method of exciting the gas to the plasma state is distinguished from the plasma CVD method. Sometimes.

  The organic compound used in the CVD method is preferably a gas that can be vaporized or vaporized at room temperature. The vaporization method includes a method of heating above the boiling point, a method of reducing the atmosphere, and the like. The organic compound to be used can be appropriately selected from carbon source materials known to those skilled in the art. Particularly preferred are compounds that are thermally decomposed by heating. For example, a compound capable of depositing carbon on a skeleton of a porous material used as a template in the CVD method (for example, on a silica gel skeleton) is preferable.

  The organic compound used may be an organic compound containing hydrogen. The organic compound may be an unsaturated or saturated organic compound or a mixture thereof. The organic compound to be used may include unsaturated linear or branched hydrocarbons having a double bond and / or triple bond, saturated linear or branched hydrocarbons, etc. Aromatic hydrocarbons and the like may be included. Examples of the organic compound include acetylene, methylacetylene, ethylene, propylene, isoprene, cyclopropane, methane, ethane, propane, benzene, a vinyl compound, ethylene oxide, and the like. Among them, it is desirable to use an organic compound that can enter the porous micropores, such as acetylene, ethylene, methane, ethane, and the like. The organic compound used for CVD at a higher temperature may be the same as or different from that used for CVD at a lower temperature. For example, acetylene, ethylene, or the like may be used for CVD at a low temperature, and propylene, isoprene, benzene, or the like may be used for CVD at a high temperature.

  When the organic compound is introduced into the micropores of the porous material, the porous material may be previously depressurized or the system itself may be depressurized. Since the porous material is stable, any method may be used as long as carbon is deposited by CVD. Usually, carbon produced by chemical reaction or thermal decomposition of an organic compound is deposited (or adsorbed) on the skeleton of the porous material to obtain a composite composed of the porous material and a microporous carbon material containing carbon. When performing CVD, the heating temperature can be appropriately selected depending on the organic compound used. Usually, it is preferable that it is 400-1500 degreeC. As for heating temperature, it is more preferable that it is 450-1100 degreeC, and it is still more preferable that it is 500-900 degreeC. Moreover, it is more preferable that it is 550-800 degreeC, and it is desirable to set it as the range of 575-750 degreeC, and also 600-700 degreeC. The heating temperature can be appropriately selected depending on the CVD processing time and / or the pressure in the reaction system. The CVD treatment time is preferably set to a time sufficient for carbon deposition, and an appropriate time can be selected depending on the organic compound used and the temperature.

CVD can be performed under reduced pressure or under vacuum, under pressure, or in an inert gas atmosphere. When performed in an inert gas atmosphere, examples of the inert gas include N ₂ gas, helium, neon, and argon. In the CVD method, usually, a gaseous organic compound can be heated while flowing in contact with the porous material together with the carrier gas, and carbon can be easily deposited on the porous material in the gas phase. The type, flow rate, flow rate, and heating temperature of the carrier gas are appropriately adjusted depending on the type of organic compound and porous material used. Examples of the carrier gas include the above-described inert gas. Considering the explosion limit, it may be a mixture with oxygen gas or hydrogen gas.

  As a condition for depositing carbon inside the micropores of the porous material by the CVD method, the filling amount of carbon in the micropores is preferably in the range of 10 to 40 wt%. Moreover, it is more preferable to control the filling amount of carbon within a range of 15 to 30 wt% based on the weight of the porous material. If the filling amount of carbon is 10 wt% or more, an amount of carbon necessary for forming the carbon skeleton is introduced, so that a stable regular structure can be obtained. If the filling amount of carbon is 40 wt% or less, the micropore volume and the BET surface area can be maintained without adhering more carbon than necessary.

  After deposition (adsorption) of carbon by CVD, the composite of the porous material and the microporous carbon material may be further heated at a temperature higher than the CVD temperature. Although this heating temperature can be suitably selected according to the organic compound to be used, it is usually 700 to 1500 ° C. The heating temperature is preferably 750 to 1200 ° C, and more preferably 800 to 1100 ° C. Moreover, it is preferable that it is 825-1000 degreeC, and it is preferable to set it as the range of 850-950 degreeC, and also 875-925 degreeC. The heating temperature can also be appropriately selected according to the heating time and / or the pressure in the reaction system. The heating time can be set to a time required for sufficient carbon deposition based on the result of analyzing the product.

  Further, an organic compound may be further introduced into the composite of the porous material and the microporous carbon material and heated to further deposit carbon. In this case, the structure of the microporous carbon material obtained by the CVD method is more stable. Carbonization may be performed by a CVD method or another heating method. Moreover, the heating temperature may be higher than the CVD temperature or may be lower. Further, the organic compound to be introduced may be the same as or different from the organic compound introduced by the CVD method. This operation may be performed a plurality of times.

  Before introducing the organic compound into the surface and the micropores of the porous material and performing CVD, the organic compound may be impregnated and carbonized. As the organic compound to be impregnated, any organic compound having a molecular size smaller than the micropore diameter of the porous material can be used. Specifically, the organic compound is preferably a thermopolymerizable monomer such as furfuryl alcohol having a high carbonization yield. As the method for impregnating the organic compound, known means can be employed, for example, if the monomer is liquid, or if it is solid, it is dissolved in a solvent and brought into contact with the porous material. In addition, it is preferable to remove the excess monomer remaining on the surface of the porous material in advance by washing or the like. For example, furfuryl alcohol can be introduced into the micropores of the porous material by bringing the porous material into contact with furfuryl alcohol under reduced pressure at room temperature and then returning the mixture to atmospheric pressure. Moreover, excess alcohol adhering to the surface of the porous material can be removed by washing with an organic solvent.

  The organic compound to be used can be used without particular limitation as long as it has a size that can be inserted into the micropores of the porous material and remains in the micropores as carbon during carbonization. Examples of the organic compound include vinyl compounds such as vinyl acetate, acrylonitrile, and vinyl chloride, vinylidene compounds such as vinylidene chloride and methyl methacrylate, vinylene compounds such as maleic anhydride, and epoxy derivatives such as ethylene oxide. In addition, sugars such as glucose and saccharose, aliphatic polyhydric alcohols, aromatic polyhydric alcohols (diols) such as resorcinol and catechol, nitrogen-containing heterocyclic compounds such as thiophene, nitrogen-containing heterocyclic compounds such as pyridine and pyrimidine Can also be used.

  When a functional group is introduced into the edge portion of the carbon material, the method is not particularly limited. For example, a method of introducing a functional group having an amidine structure by reacting a carbon material with an azo compound having an amidine structure (for example, a water-soluble azo polymerization initiator) can be preferably used. Specifically, a method of generating a radical using a water-soluble azo polymerization initiator and reacting with the edge of the carbon material can be preferably used. According to such a method, for example, when ZTC or the like is used as the carbon material, the target hydrophilic functional group can be introduced into the edge portion without lowering the structural regularity of ZTC.

  Further, usually, when preparing ZTC, it is necessary to prepare a composite of zeolite and carbon as a precursor of ZTC and then remove the zeolite by treatment with hydrofluoric acid or the like. However, the step of introducing the hydrophilic functional group can be performed simultaneously with the step of removing the zeolite. Therefore, it is not necessary to increase the reaction step in order to introduce a hydrophilic functional group, and complicated experimental operation is not required. Furthermore, since many water-soluble azo polymerization initiators are used industrially, they can be used at a relatively low cost.

  Here, the water-soluble azo polymerization initiator that can be used for introducing the amidine structure is not particularly limited, but for example, a compound represented by the following formula can be preferably used.

  The conditions for reacting the carbon material with the azo compound having an amidine structure are not particularly limited. Preferably, an azo compound having an amidine structure and a carbon material are added to the reaction vessel while purging with nitrogen, and the reaction is performed while heating and stirring. The reaction temperature can be selected so that radicals are sufficiently generated depending on the 10-hour half-life temperature of the water-soluble azo polymerization initiator used. For example, when VA-044, which is a water-soluble azo polymerization initiator and has a 10-hour half-life temperature in water of 44 ° C., the reaction temperature is, for example, 0 to 85 ° C., preferably 30 to 70 ° C. More preferably, it is 40-65 degreeC. The reaction time is, for example, 0.5 to 10 hours, preferably 1 to 6 hours.

  Although the usage-amount of the azo compound which has an amidine structure is not restrict | limited especially, it is 10-10000 mass% with respect to the mass of a carbon material, Preferably it is 100-5000 mass%, More preferably, it is 100-500 mass. %. If it is the said range, there will be no big reduction of the BET surface area of a carbon material, and the functional group which has an amidine structure can be efficiently introduce | transduced into the edge of a carbon material, maintaining the structure of a carbon material.

  In addition, when manufacturing edge modification ZTC, you may make it react with a water-soluble azo polymerization initiator using ZTC as a raw material, but it uses acid and solution, such as a hydrofluoric acid, using the composite of a zeolite and carbon as a raw material. In the reaction, it may be reacted with a water-soluble azo polymerization initiator to simultaneously introduce the amidine structure and remove the zeolite. When ZTC is used as a raw material, for example, by mixing well distilled water and ZTC in a general glass flask, bubbling an inert gas, and then adding a water-soluble azo polymerization initiator to react. Modified ZTC can be produced.

(Introducing a metal complex into a carbon material)
The method for introducing the metal complex into the carbon material is not particularly limited. For example, (1) a step of reacting a carbon material with a phosphorus compound to obtain a carbon material having a phosphorus ligand, and a reaction of the carbon material having a phosphorus ligand with a metal compound, Or (2) a method of reacting a carbon material with a metal complex.

  Hereinafter, the methods (1) and (2) will be described.

(1) reacting a carbon material with a phosphorus compound to obtain a carbon material having a phosphorus ligand; reacting the carbon material having a phosphorus ligand with a metal compound; In this method, a phosphorus ligand is first introduced into a carbon material, and then a metal complex containing a metal serving as a catalyst is introduced into the phosphorus ligand and reacted. This reaction can proceed by a ligand exchange reaction in which the ligand of the metal complex is replaced with a phosphorus ligand having strong coordination power. As a result, it can be supported as a complex in which a phosphorus ligand is coordinated to a metal atom.

  At this time, the phosphorus compound for introducing the phosphorus ligand to be used is not particularly limited, but a phosphorus compound represented by the following chemical formula may be preferably used.

In the formula, Ph ¹ and Ph ² may be the same or different, and are substituted or unsubstituted phenyl groups, and X is a halogen atom. As the halogen atom, Cl and Br are preferable, and Cl is more preferable. Examples of the substituent of Ph ¹ or Ph ^2, is not particularly limited, for example, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogenated alkyl group.

Examples of the phosphorus compound include chlorodiphenylphosphine, chlorobis (3,5-dimethylphenyl) phosphine, chlorobis (4-methoxyphenyl) phosphine, chlorobis [4- (trifluoromethyl) phenyl] phosphine, and chlorodi (p-tolyl). ) Phosphine, bis (3,5-di-tert-butyl-4-methoxyphenyl) chlorophosphine, chlorobis [3,5-bis (trifluoromethyl) phenyl] phosphine, and the like. When such a phosphorus compound is used, a complex having PPh ¹ Ph ² as a ligand can be introduced.

  There are no particular restrictions on the conditions for reacting the carbon material and the phosphorus compound. Preferably, the carbon material that has been dried by heating under vacuum and allowed to cool is reacted with the phosphorus compound, preferably in the presence of an amine, while purging with nitrogen. The reaction temperature and reaction time are not particularly limited. Preferably, the carbon material is first impregnated with an amine dissolved in a solvent, and a phosphorus compound is added thereto little by little at, for example, −100 to 10 ° C., preferably −100 to 5 ° C., and mixed. Thereafter, the temperature of the reaction solution is raised to, for example, 0 to 100 ° C., preferably 10 to 30 ° C., and reacted while stirring. The reaction time after raising the reaction temperature is preferably 0.5 to 72 hours, more preferably 2 to 24 hours, and further preferably 12 to 24 hours.

  In this case, the solvent is not particularly limited, but an aprotic polar solvent can be preferably used. Examples of the aprotic polar solvent include tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), hexamethylphosphoric triamide (HMPT), dimethylformamide (DMF), acetone, acetonitrile, and the like. Of these, THF is preferable.

  As the amine, a tertiary amine is preferably used. The tertiary amine is not particularly limited, and examples thereof include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, diethylmethylamine (N, N-diethylmethylamine), dimethylethylamine ( N, N-dimethylethylamine) and the like. Of these, triethylamine is preferable.

  Although the usage-amount of a phosphorus compound is not restrict | limited, Preferably, it is 0.1-50 mmol with respect to 1 g of carbon materials, More preferably, it is 1-20 mmol. If it is the said range, reaction can advance efficiently.

  After obtaining a carbon material having a phosphorus ligand, it is preferably washed and dried under vacuum heating and then reacted with a metal complex. The metal complex used is not particularly limited. Preferred platinum complexes include, for example, (1,5-cyclooctadiene) dimethylplatinum (II), (2,2′-bipyridine) dichloroplatinum (II), (ethylenediamine) iodoplatinum dimer, dichloro (1,10- Phenanthroline) platinum (II), dichloro (ethylenediamine) platinum (II), dichlorobis (dimethylsulfide) platinum (II), dichlorobis (ethylenediamine) platinum (II), trichloro (ethylene) platinum (II) acid salt (for example, trichloro (ethylene) ) (Potassium platinum (II) acid), hexahydroxyplatinum (IV) acid salt (for example, sodium hexahydroxyplatinum (IV)), cis-bis (acetonitrile) dichloroplatinum (II), cis-diamminetetrachloroplatinum (IV) Cis-Dichlorobis (pyridine) Gold (II), cis-diammineplatinum (II) dichloride, cis-dichlorobis (diethyl sulfide) platinum (II), cis-dichlorobis (triethylphosphine) platinum (II), cis-dichlorobis (triphenylphosphine) platinum (II) Cis-bis (benzonitrile) dichloroplatinum (II), trans-dichlorobis (triphenylphosphine) platinum (II), trans-dichlorobis (triethylphosphine) platinum (II), ethylenebis (triphenylphosphine) platinum (0) , Diaminedinitritoplatinum (II), platinum (0) -1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum (0) -2,4,6,8-tetramethyl- 2,4,6,8-tetravinylcyclotetrasiloxane complex, white (II) Acetylacetonate, tetraammineplatinum nitrate (II), dichloro (1,2-diaminocyclohexane) platinum (II), dichloro (1,5-cyclooctadiene) platinum (II), dichloro (dicyclopentadienyl) ) Platinum (II), tetraammine platinum (II) chloride, tetrakis (triphenylphosphine) platinum (0), trimethyl (methylcyclopentadienyl) platinum (IV), bis (tri-tert-butylphosphine) platinum (0) Hexachloroplatinum (IV) acid salt (for example, potassium hexachloroplatinum (IV), tetrabutylammonium hexachloroplatinum (IV)), platinum iodide, platinum chloride, and the like.

  Preferable palladium complexes include, for example, palladium chloride, chloro (1,5-cyclooctadiene) methylpalladium (II), dichloro (1,5-cyclooctadiene) palladium (II), bicyclo ([2.2.1 Hepta-2,5-diene) dichloropalladium (II), (ethylenediamine) palladium (II) chloride, and the like.

  The conditions for reacting the carbon material having the phosphorus ligand with the metal complex are not particularly limited. Preferably, the carbon material having a phosphorus ligand is reacted with a metal complex in a nitrogen atmosphere while stirring or refluxing. The reaction temperature is, for example, 0 to 150 ° C., preferably 20 to 100 ° C. The reaction time is, for example, 0.5 to 72 hours, preferably 1 to 12 hours.

The amount of the metal complex used is not particularly limited, but is preferably 0.001 to 10 mol, more preferably 0.01 to 5 mol, relative to 1 mol of the phosphorus ligand. If it is the said range, reaction can advance efficiently. After the reaction, it is filtered, washed, and dried under vacuum heating to obtain a metal-supported carbon material. The introduction rate of the metal complex with respect to the introduced phosphorus ligand can be estimated from inductively coupled plasma (ICP) emission spectroscopic analysis and ³¹ P-NMR measurement.

(2) Method of reacting carbon material and metal complex In this method, the metal complex is directly introduced into the carbon material and reacted. Depending on the coordination power of the ligand of the metal complex to be introduced, one or more of the ligands of the metal complex to be introduced can be eliminated or replaced with solvent molecules.

  The conditions for reacting the carbon material and the metal complex are not particularly limited. Preferably, the carbon material that has been dried by heating under vacuum and allowed to cool is reacted with the metal complex in a solvent while stirring or refluxing. The reaction temperature and reaction time are not particularly limited. The reaction temperature is, for example, 0 to 100 ° C, preferably 10 to 30 ° C. The reaction time is, for example, 0.5 to 72 hours, preferably 2 to 24 hours.

  The solvent is not particularly limited as long as it dissolves the metal complex, and the same solvent as in the method (1) can be used.

  Although it does not restrict | limit especially as a metal complex to be used, For example, the metal complex represented by following Chemical formula 2 may be used preferably.

Where M is selected from Group 8-10 metals;
In the formula, R ₁ and R ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms,
L ₁ and L ₂ are monodentate ligands, each independently selected from the group consisting of acetonitrile, benzonitrile, THF, diethyl sulfide, dimethyl sulfide, and pyridine; or
L ₁ and _{L 2} form a bidentate ligand linked, the bidentate ligand, dicyclopentadiene, 1,5-cyclooctadiene, Norubo Le Najien, 2,2'-bipyridine, 1 , 10-phenanthroline, ethylenediamine, N, N, N′N′-tetramethylethylenediamine, and trans, trans-dibenzylideneacetone.

  Here, the alkyl group may be linear or branched. The substituent of the alkyl group is not particularly limited, and examples thereof include a hydroxyl group, a carboxyl group, an amino group, a cyano group, and a halogen atom. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group. Octyl group, nonyl group, decyl group, and the like. Specific examples of the aryl group include a phenyl group, a biphenylyl group, a naphthyl group, and the substituent of the aryl group is not particularly limited. For example, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, Examples include halogenated alkyl groups.

Among them, a metal complex in which R ₁ and R ₂ are alkyl groups is preferable because the metal complex is easily reduced by the concerted elimination of the alkyl groups. In particular, (1,5-cyclooctadiene) dimethylplatinum (II), (1,5-cyclooctadiene) dimethylpalladium (II) and the like can be preferably used.

  The amount of the metal complex used is not particularly limited, but is preferably 0.01 to 100 wt%, and more preferably 0.01 to 30 wt%, based on the carbon material. If it is the said range, reaction can advance efficiently.

  After the reaction, it is filtered, washed, and dried under vacuum heating to obtain a metal-supported carbon material. The introduction rate of the metal complex can be estimated from inductively coupled plasma (ICP) emission spectroscopy.

(Step of obtaining a metal-supported carbon material on which metal particles are supported by heat-treating a carbon material into which a metal complex has been introduced or contacting it with hydrogen)
When the carbon material into which the metal complex produced in the above step is introduced is heat-treated or brought into contact with hydrogen, the metal complex is reduced to become a zero-valent metal. These zero-valent metals aggregate to form metal particles (metal clusters) having an average particle size of 3 nm or less and particles of 1 nm or less being 50% or more of the total number of particles. According to the method of this embodiment, since metal is first introduced as a complex, metal particles can be supported in a highly dispersed state. In addition, since the reaction can proceed gently compared with a method of obtaining metal particles using a reducing agent, a metal-supported carbon material having a predetermined particle diameter and metal particles having a uniform particle diameter can be obtained. .

  Although the mechanism by which metal particles having an average particle diameter of 3 nm or less and particles having a particle diameter of 1 nm or less are 50% or more of the total number of particles by heat treatment or hydrogen contact is not clear, In the case of the represented metal complex, heating may produce metal particles (metal clusters) having an average particle size of 3 nm or less and a particle size of 1 nm or less of 50% or more of the total number of particles by a mechanism such as the following formula. it is conceivable that.

  The heat treatment method is not particularly limited. For example, the carbon material into which the metal complex has been introduced is vacuum-heated and dried, and then preferably heated in an inert gas atmosphere. The temperature of heat processing is 100-400 degreeC, for example, Preferably it is 150-400 degreeC, More preferably, it is 200-350 degreeC, More preferably, it is 200-300 degreeC. If the temperature of heat processing is 100 degreeC or more, a metal complex will be decompose | disassembled efficiently and a metal particle may be produced | generated. Moreover, if the temperature of heat processing is 400 degrees C or less, it can suppress that a metal particle becomes large too much. Therefore, metal particles (metal clusters) having an average particle size of 3 nm or less and particles having a size of 1 nm or less of 50% or more of the total number of particles can be efficiently obtained. The time of heat processing is 0.1 to 10 hours, for example, More preferably, it is 0.5 to 2 hours. If it is the said range, the metal cluster of this embodiment can be obtained stably. Note that the heat treatment may be performed a plurality of times.

  Further, in the case of the metal complex represented by the above chemical formula 2, by hydrogen treatment, a metal having an average particle size of 3 nm or less and a particle size of 1 nm or less is 50% or more of the total number of particles by the mechanism as shown in the following formula It is thought that particles (metal clusters) can be generated.

  The conditions for the hydrogen treatment are not particularly limited. For example, after the carbon material into which the metal complex has been introduced is dried by heating under vacuum, an inert gas such as nitrogen is introduced. Thereafter, hydrogen gas is circulated at, for example, 10 to 1000 cc / min, preferably 20 to 200 cc / min, and at a temperature of 0 to 150 ° C., preferably 20 to 100 ° C., for example, for 0.1 to 10 hours, More preferably, it is contacted with hydrogen for 0.5 to 5 hours. If the temperature when contacting with hydrogen is 0 ° C. or higher or the time when contacting with hydrogen is 0.1 hour or longer, the metal complex can be efficiently decomposed and metal particles can be generated. Moreover, if the temperature at the time of making it contact with hydrogen is 150 degrees C or less or the time to make it contact with hydrogen is 10 hours or less, it can suppress that a metal particle becomes large too much. Therefore, even under the above conditions, a metal cluster having an appropriate particle size and little variation in particle size can be obtained efficiently. Note that the hydrogen treatment may be performed a plurality of times at the same temperature or at different temperatures. For example, the hydrogen treatment may be performed a plurality of times while raising the temperature stepwise. When the hydrogen treatment is performed a plurality of times, the total time for contacting with hydrogen is preferably in the above range. Moreover, it is preferable that the temperature when making it contact with hydrogen is the said range in at least 1 time of hydrogen treatment. As will be described later, the metal complex may be gradually formed by contact with hydrogen during the hydrogen adsorption / desorption measurement cycle of the carbon material introduced with the metal complex. In such a case, instead of the hydrogen treatment described above, the hydrogen adsorption / desorption measurement cycle may be performed as a step of contacting with hydrogen.

<Hydrogen storage material>
The metal-supported carbon material according to the present embodiment has a high hydrogen storage capacity, and can store and release hydrogen at a temperature of 100 ° C. or lower. In addition, since no chemical reaction is involved in the storage and release of hydrogen, the durability is excellent. Therefore, it can be suitably used particularly as a hydrogen storage material for fuel cell vehicles.

<Catalyst material>
The metal-supported carbon material according to the present embodiment can support a metal in a highly active state. Moreover, the metal usage-amount can be reduced by setting it as a metal cluster of about several atoms-dozens of atoms. Therefore, a catalyst material with improved activity per mass of catalyst metal can be obtained. The metal-supported carbon material according to the present embodiment can be suitably used for various catalysts such as a fuel cell electrode catalyst.

  The effects of the present invention will be described with reference to the following examples. However, the technical scope of the present invention is not limited only to the following examples.

<Reference Example 1: Preparation of ZTC>
The dried zeolite (NaY5.5) was impregnated with furfuryl alcohol (FA). This was heat-treated at 150 ° C. for 8 hours to polymerize FA to obtain a PFA / zeolite composite. This was heated to 850 ° C. at 5 ° C./min in an N ₂ atmosphere, and then propylene CVD was performed at 700 ° C. for 1 hour. Thereafter, the temperature was raised to 900 ° C. at 5 ° C./min in an N ₂ atmosphere and held for 3 hours to prepare a carbon / zeolite composite. Finally, the composite was put into 100 ml of 47 wt% hydrofluoric acid, stirred for 5 hours and treated with hydrofluoric acid to dissolve and remove the zeolite as a template to remove ZTC as a microporous carbon material (MPC). Obtained.

The obtained sample had a BET surface area S _BET of 3690 m ² / g.

<Preparation of carbon material with metal complex introduced>
(Example 1: Preparation of ZTC-Pt)
ZTC prepared in Reference Example 1 was reacted with (1,5-cyclooctadiene) dimethylplatinum (II) in acetonitrile to obtain a carbon material into which a Pt complex represented by the following formula was introduced.

  Specifically, a magnetic stirrer bar and 1.0 g of ZTC prepared in Reference Example 1 were placed in a 200 ml two-necked flask, a silicone rubber septum and a three-way cock were attached, and heated to 150 ° C. for 6 hours. Vacuum-dried. After drying, the flask was allowed to cool and then kept at 25 ° C. using a thermostatic bath. Subsequently, 40 ml (Pt: 0.089 mmol) of a (1,5-cyclooctadiene) dimethylplatinum (II) / acetonitrile solution prepared in advance was injected from the septum using a syringe and stirred for 6 hours. The (1,5-cyclooctadiene) dimethylplatinum (II) / acetonitrile solution used was prepared as follows. A magnetic stir bar was placed in a 100 ml two-necked eggplant type flask, and 32.8 mg of (1,5-cyclooctadiene) dimethylplatinum (II) was added. Next, 44 ml of dehydrated acetonitrile (Wako Pure Chemical Industries, Ltd.) was added and stirred for several minutes to dissolve (1,5-cyclooctadiene) dimethylplatinum (II) (1,5-cyclooctadiene). A dimethylplatinum (II) / acetonitrile solution was prepared.

  After stirring for 6 hours, the reaction solution was filtered using a 0.1 μm membrane filter (H010A047A manufactured by ADVANTEC, φ = 47 mm), and then 200 ml of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd.), followed by 100 ml of Washing was performed using tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.). The washed sample was put into a 200 ml two-necked flask together with a magnetic stirrer bar, a three-way cock and a glass stopper were attached, and dried under vacuum heating at 100 ° C. for 6 hours. Let the obtained sample be ZTC-Pt.

The ICP analysis value of the obtained sample was Pt: 13.3 wt%. In addition, S _BET was 2570 m ² / g.

(Example 2: Preparation of ZTC-P-Pt)
About ZTC prepared in Reference Example 1, diphenylphosphine ligand was introduced, and then ZTC into which diphenylphosphine ligand was introduced was reacted with (1,5-cyclooctadiene) dimethylplatinum (II) in acetonitrile, The carbon material which introduce | transduced Pt complex like a following formula was obtained.

  Specifically, a magnetic stirrer bar and 300 mg of ZTC prepared in Reference Example 1 were placed in a 50 ml two-necked eggplant type flask, and a silicone rubber septum and a three-way cock were attached to the mouths of the flasks, respectively. While stirring using a stirrer bar, the ZTC was heated to 150 ° C. and dried under vacuum heating for 6 hours. After drying, the flask was allowed to cool to room temperature. Next, in a state where the dried flask containing ZTC was decompressed, 20 ml of a THF / triethylamine solution prepared in advance was injected from the septum using a syringe and stirred at room temperature for 10 minutes. Here, the THF / triethylamine solution was added to a nitrogen-substituted 50 ml two-necked eggplant type flask by adding 25 ml of dehydrated THF (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.536 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) at room temperature. And prepared by stirring for a few minutes. Subsequently, after the flask was cooled to 0 ° C. using a thermostatic bath and stirred for 30 minutes, the flask was purged with nitrogen until 1 atm, and 0.788 g of chlorodiphenylphosphine (manufactured by Wako Pure Chemical Industries, Ltd.) was added. It added to the flask using the syringe and stirred for 10 minutes. Thereafter, the temperature of the thermostatic bath was set to 25 ° C., and after reaching 25 ° C., the mixture was further stirred for 15 hours to be reacted. Thereafter, the mixture was filtered through a membrane filter (0.1 μm, T010A047A manufactured by ADVANTEC), and further washed well with 150 ml of THF. Next, the sample was thoroughly washed by stirring in 2000 ml of ion exchange water for 30 minutes, filtered through a membrane filter (0.1 μm, H010A047A manufactured by ADVANTEC), and then the sample was dried under reduced pressure at 150 ° C. for 6 hours. This sample is designated as ZTC-P.

  120 mg of ZTC-P prepared above and a magnetic stirrer bar were placed in a Schlenk tube, and a silicone rubber septum was attached to the mouth of the Schlenk tube. While stirring using a stir bar, ZTC-P was vacuum-heated and dried at 150 ° C. for 6 hours, and then allowed to cool to room temperature. Subsequently, 4.8 ml of a (1,5-cyclooctadiene) dimethylplatinum (II) / acetonitrile solution (Pt: 1.5 mmol / (1 g) prepared in advance in a state where the dried Schlenk tube containing ZTC-P was decompressed. -ZTC-P)) was injected from the septum using a syringe and stirred for 10 minutes. As for the (1,5-cyclooctadiene) dimethylplatinum (II) / acetonitrile solution, 60 mg of (1,5-cyclooctadiene) dimethylplatinum (II) (manufactured by Aldrich) was added to a 20 ml one-necked eggplant type flask. The flask was purged with nitrogen, and 4.8 ml of dehydrated acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) was added and the mixture prepared by stirring for several minutes at room temperature was used.

  Next, a reflux condenser was attached to the Schlenk tube, and the flask was heated in an oil bath heated to 100 ° C. and refluxed for 12 hours. After 12 hours, the reflux was stopped and the Schlenk tube was allowed to cool. Then, the reaction solution was filtered using a 0.1 μm membrane filter (ADVANTEC H010A047A, φ = 47 mm), and then 50 ml of acetonitrile (Wako Pure). Washed with 50 ml of diethyl ether. The washed sample was vacuum-heated and dried at 100 ° C. for 6 hours. The obtained sample is represented as ZTC-P-Pt.

From the ICP analysis of the obtained sample, it was found that phosphorus contained in the sample was 1.48 wt% and Pt was 10.3 wt%. In addition, S _BET was 1860 m ² / g.

(Example 3: Preparation of ZTC-Pt (comp))
An edge-modified microporous carbon material was prepared according to the following reaction formulas (1) and (2).

  Specifically, 46 wt% hydrofluoric acid (200 g) was added to a PTFE 4-neck flask (500 ml), and nitrogen gas was bubbled in advance at 100 cc / min for 30 minutes or more in order to remove dissolved oxygen gas. It was. Subsequently, VA-044, which is a water-soluble azo polymerization initiator, was added so as to be 2.50 wt% with respect to the total weight of the reaction solution, and heating was started at an oil bath set temperature of 70 ° C. When the temperature of hydrofluoric acid in the flask reached 50 ± 2 ° C., the carbon / zeolite composite prepared in Reference Example 1 (0.47 g) was added and stirred for a certain time. Approximately 1 hour after adding the carbon / zeolite composite, the temperature of the hydrofluoric acid in the flask was 60 ± 2 ° C. The reaction time was 6 hours after the hydrofluoric acid temperature reached 60 ° C.

  After the reaction, the reaction solution was filtered, and the product was washed well with 500 ml of distilled water, and further stirred with distilled water (500 g) for 30 minutes so that no ash remained. Thereafter, it was filtered and washed with distilled water to obtain an edge-modified microporous carbon material. Yield was 0.11 g.

  Next, a phosphorus ligand was introduced into the edge-modified microporous carbon material according to the following formula.

780 mg of ZTC (ZTC-VA044) having an amidine structure introduced therein and a stirrer bar were added to a linear flask having an outer diameter of 35 mm, dried by vacuum heating at 150 ° C. for 6 hours, and then allowed to cool to room temperature. Subsequently, while stirring the stirrer, 50 ml (triethylamine 1.13 g, 11.20 mmol) of 2.62 wt% triethylamine / THF solution was injected into the flask using a syringe and impregnated in vacuum. Thereafter, the flask was cooled in a water bath at 0 ° C. (addition of about 15% by weight of ethylene glycol) using a thermostatic bath. After 30 minutes, the flask was purged with nitrogen up to atmospheric pressure, and 2.26 g (10.25 mmol) of chlorodiphenylphosphine (manufactured by Aldrich) was poured into the flask using a syringe while flowing nitrogen so that air did not enter the flask. And stirred for 10 minutes. Thereafter, the temperature of the water bath was set to 25 ° C., and the reaction was performed for 15 hours after reaching 25 ° C. Thereafter, 80 ml of THF was added to the reaction solution and stirred for several minutes, followed by filtration with a membrane filter (0.1 μm, T010A047A manufactured by ADVANTEC), and further washed well with 500 ml of THF. Next, the sample was thoroughly washed by stirring in 2500 ml of distilled water for 30 minutes, filtered through a membrane filter (0.1 μm, H010A047A manufactured by ADVANTEC), and then the sample was vacuum dried at 150 ° C. The yield was 0.87g. This sample represents the ZTC-VA044-PPh _2.

  The platinum complex was introduced into an edge-modified microporous carbon material having a phosphorus ligand according to the following formula.

After 0.30 g of ZTC-VA044-PPh ₂ prepared above was vacuum-heated and dried at 150 ° C. for 6 hours, it was allowed to cool to room temperature and stirred with a stirrer, and 1.56 wt% ( 12 ml of 1,5-cyclooctadiene) dimethylplatinum (II) complex / acetonitrile solution was injected, vacuum impregnated, stirred for about 10 minutes, and then purged with nitrogen until atmospheric pressure was reached. Subsequently, the flask was fitted with a condenser and refluxed in an oil bath heated to 100 ° C. for 12 hours. After refluxing, the reaction solution was cooled to room temperature, filtered through a membrane filter (0.1 μm, H010A047A manufactured by ADVANTEC), washed with 100 ml of acetonitrile, and then with 100 ml of diethyl ether, and then dried under vacuum. (100 ° C., 6 hours). This sample is represented as ZTC-Pt (comp). The yield was 0.37g.

The phosphorus contained in the sample was 1.62 wt%, and platinum was 11.1 wt%. The BET surface area was 1550 g / m ² .

(Comparative Example 1: ZTC-Pt particles)
In order to compare with ZTC carrying the complex, Pt nanoparticles were carried on ZTC using a general method. Prepared 6.7 ml of 0.096 wt% aqueous solution of diammine dinitroplatinum [Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ] and 66.7 ml of 0.0095 wt% aqueous solution of sodium borohydride as a reducing agent aqueous solution. And cooled to 0 ° C. Subsequently, 100 mg of ZTC prepared in Reference Example 1 was added to a 0 ° C. diamminedinitroplatinum aqueous solution, cooled to 0 ° C., and stirred in a reduced pressure atmosphere for 30 minutes. Next, this solution was centrifuged, mixed with an aqueous sodium borohydride solution at 0 ° C., and stirred at 0 ° C. for 10 minutes to reduce diammine dinitroplatinum to produce platinum nanoparticles. The reaction solution was filtered using a 0.1 μm membrane filter (H010A047A manufactured by ADVANTEC, φ = 47 mm), the sample was thoroughly washed with ion-exchanged water, and dried under reduced pressure at 150 ° C. for 6 hours. This sample is represented as ZTC-Pt particles. Platinum was 2.28 wt% in the sample. The BET surface area was 3260 g / m ² . This sample is represented as ZTC-Pt particles.

Table 1 below shows the BET surface area S _BET and the pore structure calculated from the results of nitrogen adsorption / desorption measurement of the samples prepared in Reference Example 1, Examples 1 to 3 and Comparative Example 1. Here, _VTotal , _Vmicro , and _Vmeso represent the volume occupied by all pores, the volume occupied by micropores, and the volume occupied by mesopores, respectively.

  In addition, the measurement of the BET surface area of the carbon material prepared by each Example, the comparative example, and the reference example was performed using BELSORP mini by Nippon Bell, and was performed by the multipoint method at the temperature of -196 degreeC.

  The contents of phosphorus and platinum were measured by inductively coupled plasma (ICP) emission spectroscopy. Here, the content of phosphorus and platinum used was a value measured using an inductively coupled plasma (ICP) emission spectroscopic analyzer manufactured by SII Nano Technology after the sample was decomposed by alkali melting into a solution. Table 1 shows the platinum content.

  TEM observation was performed about the carbon material which introduce | transduced the metal complex prepared in each Example.

  The transmission electron microscope (TEM) was observed using a transmission electron microscope JEM-2010 manufactured by JEOL Ltd. at an acceleration voltage of 200 kV. In TEM observation, a small amount of ethanol was added to the sample and then suspended by sonication, and the suspension was dropped on a microgrid (Oken Shoji Co., Ltd .: popular product type B) at 40 ° C. The sample was dried under reduced pressure for 30 minutes to obtain an observation sample for TEM.

  3A to 3E show TEM photographs of materials into which the metal complexes prepared in Reference Example 1, Examples 1 to 3, and Comparative Example 1 were introduced, respectively. About each figure, (b) observes (a) at high magnification. As shown in FIG. 3E, in the TEM photograph of the sample of Comparative Example 1, platinum particles having an average particle diameter of 1 to 3 nm can be confirmed. However, in the sample of Example 1 shown in FIG. 3B, Pt on the particles was not observed even though the amount of Pt supported was 13.3 wt% compared to 2.28 wt% of Comparative Example 1. . From this, it is considered that in the sample of Example 1, platinum does not aggregate and is uniformly dispersed on the surface of the carbon material. Similarly, as shown in FIGS. 3C and 3D, particulate Pt having a size that can be detected by the samples of Examples 2 and 3 is not observed, and it is considered that platinum is uniformly dispersed.

<Heat treatment>
The carbon material into which the metal complex prepared in each example was introduced was subjected to heat treatment. The sample was subjected to vacuum heat treatment at 200 ° C. or 300 ° C. for 1 hour. The vacuum heat treatment was performed by using a pretreatment device Belprep for adsorption measurement manufactured by Nippon Bell Co., Ltd. Prior to the heat treatment, vacuum heating drying was performed at 100 ° C. (temperature rising in 1 hour) for 6 hours, and then the temperature was increased to a predetermined temperature at 10 ° C./min and vacuum heating treatment was performed for 1 hour.

<Hydrogen treatment>
About the carbon material which introduce | transduced the metal complex prepared in each Example, hydrogen treatment was performed for 30 minutes at each temperature in order of 25 degreeC, 50 degreeC, and 70 degreeC.

  Specifically, a sample and a stirrer bar were added to the flask, and the sample was dried by vacuum heating and drying at 100 ° C. for 6 hours. After drying the sample, the flask was allowed to cool, and then the flask was held at 25 ° C. using a thermostatic bath, and nitrogen gas was introduced into the flask. Subsequently, hydrogen gas was passed through the flask at 100 cc / min, and hydrogen treatment was performed at 25 ° C. for 30 minutes. After 30 minutes, the flask was evacuated and then heated to 50 ° C. with an oil bath to introduce nitrogen gas into the flask. Subsequently, hydrogen gas was passed through the flask at 100 cc / min, and hydrogen treatment was performed at 50 ° C. for 30 minutes. After 30 minutes, the flask was evacuated and then heated to 70 ° C. with an oil bath to introduce nitrogen gas into the flask. Subsequently, hydrogen gas was passed through the flask at 100 cc / min, and hydrogen treatment was performed at 50 ° C. for 30 minutes. After 30 minutes, the flask maintained at 70 ° C. was evacuated for 1 hour to remove hydrogen gas in the flask, and then the flask was allowed to cool. After allowing to cool, nitrogen gas was introduced into the flask, and the flask was moved into a glove box under an argon atmosphere, and a sample was taken out.

  The sample prepared in each example was subjected to powder X-ray diffraction measurement before and after the heat treatment and before and after the hydrogen treatment, and the formation of nanoclusters by the heat treatment and the hydrogen treatment was observed. The powder X-ray diffraction measurement was performed using XRD-6100 manufactured by Shimadzu Corporation, and the radiation source was Cu-Kα, the voltage was 30 kV, and the current was 20 mA.

  FIG. 4A shows XRD patterns obtained by measuring the sample prepared in Example 1 in an air atmosphere before and after heat treatment and hydrogen treatment. In the sample of Example 1, an X-ray diffraction pattern before heat treatment and hydrogen treatment clearly shows a peak showing a long-period regular structure in the vicinity of 2θ = 6 °, and a stack of carbon network surfaces at 2θ = 20-30 °. There were almost no peaks derived from. From this, it was confirmed that the ordered structure of the microporous carbon material (MPC) was maintained in the obtained sample. In addition, no peak derived from zero-valent Pt particles was observed.

  However, when heat treatment was performed at 200 ° C., a peak derived from zero-valent platinum was observed in the vicinity of 2θ = 40 °, and a stronger peak was confirmed when heat treatment was performed at 300 ° C. This indicates that the growth of platinum particles is progressed by the heat treatment.

In addition, it was confirmed that platinum particle growth progressed as it proceeded to 25 ° C., 50 ° C., and 70 ° C. even in the case of hydrogen treatment.

  In addition, FIG. 4A shows XRD patterns measured in an air atmosphere before and after hydrogen treatment of the sample prepared in Example 2. Even when the sample of Example 2 was treated with hydrogen, it was confirmed that the particle growth of platinum progressed as it proceeded to 25 ° C., 50 ° C., and 70 ° C.

  For comparison, FIG. 4B shows XRD spectra of the sample of Reference Example 1 (ZTC) and the sample of Comparative Example 1 (ZTC-Pt particles). In the XRD spectra of the sample of Reference Example 1 and the sample of Comparative Example 1, the peak around 2θ = 6 ° indicates the long-period regular structure of the carbon material, and the XRD pattern of the sample of Comparative Example 1 is around 2θ = 40 °. The peak is derived from particulate platinum.

  5A and 5B show TEM photographs of the sample prepared in Example 1 after heat treatment at 200 ° C. and 300 ° C., respectively. 5A and 5B, (a) to (d) are observations of different regions of the sample. As shown in FIG. 5A, in the sample heat-treated at 200 ° C., platinum particles having a size of less than 1 nm were highly dispersed inside the ZTC particles, and almost no particles having a size of 1 nm or more could be confirmed. On the other hand, as shown in FIG. 5B, many of the ZTC particles in which particles of 1 nm or less were highly dispersed and those in which particles of about 1 nm were highly dispersed were observed after heat treatment at 300 ° C.

  FIG. 6A shows a TEM photograph measured after hydrogen-treating the sample prepared in Example 1 at 25 ° C. and 50 ° C., and FIG. 6B shows a TEM photograph measured after further hydrogen-treating at 70 ° C. FIG. 7A shows a TEM photograph measured after hydrogen treatment of the sample prepared in Example 2 at 25 ° C. and 50 ° C., and FIG. 7B shows a TEM photograph measured after further hydrogen treatment at 70 ° C. It can be seen that in the hydrogen treatment at 25 ° C. and 50 ° C., particles of 1 nm or less are dispersed in any of the samples of Examples 1 and 2. However, when compared with the sample heat-treated at 200 ° C. in FIG. 5A, the particle size became slightly non-uniform. Further, when the hydrogen treatment is performed at 70 ° C., the metal particles in the sample of Example 1 are considered to be about 1 nm at the largest. In the sample of Example 2, it is considered that most of the particles are 1 nm or less, but particles of 1 nm or more are also observed. In these TEM photographs, (a) to (d) are the same samples observed at different magnifications and regions.

  Next, the formation process of platinum clusters by hydrogen treatment was observed for the samples of Example 1 and Example 2 by X-ray absorption fine structure analysis (XAFS).

XAFS measurement was performed on three samples of ZTC-Pt, ZTC-P-Pt, and ZTC-Pt particles using transmission-type conventional XAFS. The sample was vacuum-heated and dried at 100 ° C. for 6 hours in advance to remove adsorbed water, and pellets were prepared from about 100 mg of the sample dried in an argon atmosphere glove box. The prepared pellet was set in the XAFS measurement sample cell, and then the cell was confined and set in the measuring apparatus. In the measurement, the sample was treated with hydrogen flow in the range from room temperature to 100 ° C. according to the following procedure, returned to the helium atmosphere, allowed to cool to room temperature, and then XAFS was performed:
(1) XAFS measurement in a helium atmosphere at room temperature,
(2) After hydrogen treatment at room temperature and hydrogen treatment for 30 minutes, return to the helium atmosphere again and perform XAFS measurement.
(3) The temperature was raised to a predetermined temperature in a helium atmosphere, and after reaching the predetermined temperature, hydrogen treatment was performed for 30 minutes. After returning to the helium atmosphere and allowing to cool to room temperature, XAFS measurement was performed. The temperature was 50 ° C., 70 ° C., and 100 ° C., followed by hydrogen treatment at each temperature, and after cooling to room temperature in a helium atmosphere, XAFS measurement was performed.

  8 to 10 show XAFS measurement results of the samples prepared in Example 1, Example 2, and Comparative Example 1, respectively. In each figure, (a) shows the absorption edge fine structure (XANES), and (b) shows the wide area X-ray absorption fine structure (EXAFS) (radial distribution function obtained by Fourier transform).

  As shown in FIG. 10A, the electronic state of the sample prepared in Comparative Example 1 does not change before and after the hydrogen treatment. In FIG. 10B, a peak derived from the Pt—Pt bond was observed in the vicinity of 2.6 mm, but this peak does not change before and after the hydrogen treatment. This is because platinum is supported as particles and the particles are not changed by hydrogen treatment.

  On the other hand, as shown in FIG. 8 (b), in the sample of Example 1, the peak near 2.6Å derived from the Pt-Pt bond in the spectrum after hydrogen treatment became strong, and 1.6Å derived from the platinum complex. Nearby peaks are weak. This indicates that platinum is sintered and the complex is decomposed as the hydrogen treatment progresses.

  Similarly, in the sample of Example 2 shown in FIG. 9B, it can be seen that platinum is sintered as the temperature of the hydrogen treatment increases.

  Furthermore, the wide area X-ray absorption fine structure (EXAFS) measured about the sample of Example 1, Example 2, and the comparative example 1 was analyzed, and the coordination element kind and average coordination number of platinum were calculated | required. The average coordination number of platinum was calculated by extracting a Pt-Pt bond from a radial distribution function obtained by Fourier transforming EXAFS data, and performing curve fitting after inverse Fourier transform. Pt foil (coordination number 12) was used as a standard sample.

  FIG. 11 (a) shows the samples prepared in Example 1, Example 2, and Comparative Example 1, respectively, before the hydrogen treatment (room temperature, in He) and after the hydrogen treatment (room temperature, 50 ° C., 70 ° C., It is the figure which plotted the average coordination number of platinum calculated | required from EXAFS of the sample of 100 degreeC), and the average coordination number of the carbon atom or nitrogen atom around a platinum atom.

  Furthermore, the average particle diameter of the platinum particles was estimated from the average coordination number of platinum atoms contained in the platinum particles (platinum clusters) as follows.

  Pt lattice constant: 0.39231 nm, Pt metal bond radius: 0.14 nm, one side of unit cell (fcc): 0.67 nm, unit cell 1 (63 atoms), unit cell 2 (number of atoms 14) shown below ), Octahedral clusters (6 atoms), and tetrahedral clusters (4 atoms) were calculated to calculate the equivalent sphere diameter, which was used as the particle size of the platinum particles. In addition, the average coordination numbers of platinum atoms constituting the unit cells 1 and 2, the regular octahedral cluster, and the regular tetrahedral cluster were calculated. And the relationship between the average coordination number of a platinum atom and the average particle diameter of a platinum particle was plotted in FIG.11 (c). Here, the particle diameter of one platinum atom (average coordination number 0) was atomic radius × 2 = 0.28 nm. Using the relationship between the average coordination number of platinum atoms and the average particle diameter of platinum particles thus obtained, the metal particles corresponding to the average coordination number of platinum atoms obtained in FIG. The average particle size can be estimated.

  As shown in FIG. 11A, in the sample of Comparative Example 1, the average coordination number (Pt−Pt) of platinum atoms is about 7 and does not change before and after the hydrogen treatment. This is consistent with the result of FIG. Furthermore, from FIG. 11C, when the average coordination number is 7, the average particle diameter of the metal particles can be estimated to be about 1.75 nm, which is consistent with the result of FIG. 3E.

  On the other hand, in the samples of Example 1 and Example 2, although the average coordination number (Pt-Pt) of platinum atoms before hydrogen treatment is close to 0, platinum atoms can be obtained by hydrogen treatment, particularly at high temperatures. The average coordination number of increases. At the same time, the average coordination number between the platinum atom and the nitrogen or carbon atom is reduced by the hydrogen treatment. This suggests that platinum is introduced into the carbon material as a complex, but the ligands are desorbed with the hydrogen treatment, and the platinum atoms aggregate to form a cluster. Match the result. Furthermore, even after hydrogen treatment, the average coordination number of platinum atoms (Pt-Pt) is 4.0 or less, which is an average particle size of 0.65 nm or less with reference to FIG. It corresponds to the metal particles. It is difficult to observe particles of such a size with a TEM.

  In FIG. 11 (b), the samples prepared in Example 1, Example 2, and Comparative Example 1 were each subjected to a sample before hydrogen treatment (room temperature, in He) and after hydrogen treatment (room temperature, 50 ° C., 70 ° C.). The interatomic distance of platinum-platinum and the interatomic distance between platinum and carbon or nitrogen determined from EXAFS of a sample at (° C., 100 ° C.) are shown. As shown in FIG. 11B, in the sample prepared in Comparative Example 1, the interatomic distance between platinum atoms does not change before and after the hydrogen treatment. On the other hand, in the samples prepared in Examples 1 and 2, as in FIGS. 8 to 10, it was found that the interatomic distance between platinum atoms changed to a value almost equal to that in Comparative Example 1 after the hydrogen treatment.

  The evaluation of the hydrogen storage capacity is performed at 25 to 100 ° C. using a high-precision automatic gas / vapor adsorption measuring device (BEL SORP MAX, manufactured by Nippon Bell Co., Ltd.) as a low-pressure storage performance measurement (˜0.1 MPa = 100 kPa). The hydrogen adsorption / desorption isotherm was measured. The sample was vacuum-heated and dried at 100 ° C. for 6 hours before measurement. In order to avoid the adsorption of moisture when exposed to air, the sample was dried by the measuring apparatus main body, and then the adsorption / desorption measurement was performed without removing the sample tube. The dead volume was measured after the adsorption measurement. The equilibrium judgment condition was that the pressure change for 500 seconds was within 0.3% of the reading of the pressure gauge.

Moreover, as a high-pressure occlusion performance measurement (-10 MPa), a hydrogen adsorption / desorption isotherm at 20 to 80 ° C. was measured using a hydrogen adsorption evaluation apparatus (Resca Co., Ltd. = current Fuse Technonet Co., Ltd.). Before the measurement, the sample was heated and dried at 80 ° C. until the degree of vacuum dropped to 10 ⁻³ Pa or less. The adsorption / desorption measurement was performed as it was. The dead volume was measured before the adsorption measurement. As the equilibrium judgment condition, a pressure gauge reading in which the pressure change for 300 seconds settled to less than 1 kPa was adopted.

  The result of the low-pressure hydrogen measurement of the sample prepared in Example 2 is shown in FIG. 12A. In the hydrogen adsorption / desorption measurement of FIG. 12A, the sample prepared in Example 2 was not subjected to the hydrogen treatment by the above-described method, but the metal complex was measured in the measurement of the hydrogen adsorption / desorption isotherm. When contacted with hydrogen, the properties gradually change and platinum nanoclusters are formed. Therefore, the effect as in the case of performing a separate hydrogen treatment can be obtained. The sample prepared in Example 2 dramatically increased the amount of occluded hydrogen with increasing temperature (FIG. 14), despite about half of the sample of Comparative Example 1 carrying Pt particles with a surface area of 1 to 3 nm. The hydrogen storage capacity was extremely high. This shows a high value that cannot be explained by the amount of hydrogen molecules chemisorbed on the platinum complex, indicating that the spillover activity is extremely high. As described above, since the metal complex introduced into ZTC can be decomposed upon contact with hydrogen to generate platinum clusters, such a high spillover activity is derived from such a predetermined size of the platinum clusters. It is thought to be a thing. In addition, a high hydrogen storage amount was obtained in the sample of Example 1 as well (FIG. 14). FIG. 14 is a diagram showing hydrogen adsorption / desorption isotherms of the samples manufactured in Examples 1 and 2 in comparison with the samples of Reference Example 1 and Comparative Example 1.

  FIG. 12B shows hydrogen adsorption / desorption isotherms measured at 25 ° C. and 50 ° C., respectively, for the sample prepared in Example 1 and subjected to hydrogen treatment in the order of 25 ° C., 50 ° C., and 70 ° C. for 30 minutes. In addition, the hydrogen adsorption / desorption isotherm of the sample before hydrogen treatment measured at 25 ° C. and the hydrogen adsorption / desorption isotherm of the sample of Reference Example 1 and the sample of Comparative Example 1 measured at 25 ° C. are shown. In the figure, the dotted line attached to each isotherm represents the slope of the ZTC adsorption isotherm, and the portion where the slope increased compared to the ZTC adsorption isotherm corresponds to the hydrogen storage amount due to the effect of spillover. . As shown in FIG. 12B, even a sample that has not been subjected to hydrogen treatment shows a higher hydrogen storage capacity than ZTC that does not support platinum or ZTC that supports Pt particles of 1 to 3 nm, and is 10 kPa or more. The slope of the adsorption isotherm is large. In addition, the hydrogen storage amount increased by performing hydrogen treatment for 30 minutes at each temperature in the order of 25 ° C., 50 ° C., and 70 ° C., and the hydrogen storage amount further increased when the measurement temperature was changed from 25 ° C. to 50 ° C. From this result, it was confirmed that by introducing hydrogen and reducing the metal complex to obtain particles having a specific particle size, the hydrogen storage amount increases and the effect of hydrogen storage by spillover is high.

FIG. 12C shows hydrogen adsorption / desorption isotherms measured at 25 ° C. and 50 ° C., respectively, for the sample prepared in Example 2 and subjected to hydrogen treatment in the order of 25 ° C., 50 ° C., and 70 ° C. for 30 minutes. In addition, the maximum value of the number of moles of occluded hydrogen (H ₂ / Pt) with respect to the supported amount of platinum is shown. As in the case of Example 1, the sample prepared in Example 2 showed higher hydrogen storage capacity than ZTC not supporting platinum or ZTC supporting 1 to 3 nm Pt particles. Furthermore, hydrogen storage amount increased by hydrogen-treating for 30 minutes at each temperature in order of 25 degreeC, 50 degreeC, and 70 degreeC. Here, the hydrogen occlusion amount after the hydrogen treatment is smaller than that of the sample of Example 1, but in the sample of Example 2, the particle size of platinum particles generated by the hydrogen treatment is larger than that in Example 1. This is thought to be due to the tendency. Further, when the measurement temperature was increased from 25 ° C. to 50 ° C., the hydrogen storage amount further increased and the value of H ₂ / Pt also increased.

  The high-pressure hydrogen storage characteristics up to 10 MPa were measured in the range of 20 to 80 ° C. according to the measurement method of the pressure-composition isotherm of the JISH7291 hydrogen storage alloy. The results are shown in FIG. (A) is ZTC of the reference example 1, (b) is ZTC which introduce | transduced 1-3 nm Pt particle | grains of the comparative example 1, (c) is a result of the sample which introduce | transduced the complex of Example 3. FIG. At this time, the complex introduced into the metal-supported carbon material of Example 3 can generate platinum clusters by contacting with hydrogen during measurement.

  As shown in FIG. 13 (a), the hydrogen storage capacity of ZTC not supporting metal decreases with temperature in a typical physical adsorption behavior. As shown in FIG. 13 (b), the ZTC-Pt particles have a smaller surface area than ZTC, so that the hydrogen storage amount by physical adsorption decreases, but the hydrogen storage amount at 20 to 60 ° C. is the same as that of ZTC. It increased from ZTC at ° C. This is presumably because the spillover effect was strongly expressed at 60 to 80 ° C.

  As shown in FIG. 13 (c), the metal-carrying carbon material of Example 3 obtained a hydrogen storage amount that exceeded the value expected from the surface area, even though the surface area was less than half of ZTC. This indicates that a metal cluster of a predetermined size has a larger spillover effect compared to 1 to 3 nm nanoparticles. It was also confirmed that hydrogen was reversibly released by reducing the pressure.

  Further, for the hydrogen storage amount measured with the metal-supported carbon material of Example 3 and Comparative Example 1, the hydrogen storage amount by spillover was subtracted from the hydrogen storage amount by physical adsorption estimated from the adsorption isotherm of unsupported ZTC. Asked. As a result, in the sample of Comparative Example 1, the hydrogen storage amount by spillover was 10% of the total hydrogen storage amount, whereas in the sample of Example 3, the hydrogen storage amount by spillover was a value close to 0.3 wt%. This accounted for 46% of the total hydrogen storage.

  From the above, it can be seen that the metal-supported carbon material of the present invention has a metal cluster with high spillover activity, and the hydrogen storage capacity can be greatly improved.

  In this way, the metal can be supported in a highly dispersed state by supporting the metal complex on the carbon material. Furthermore, metal complexes can be converted into nanoclusters of a predetermined size with high spillover activity by a simple method such as heat treatment or hydrogen treatment, compared to the case where particulate metals of about 1 to 3 nm are supported. It was revealed that the hydrogen storage capacity was greatly improved.

1 zeolite,
1a, 2a micropore (micropore),
2 Zeolite carbon (zeolite template carbon),
3 Complex.

Claims (8)

A metal-supported carbon material in which metal particles are supported on a carbon material having pores, and the average particle size of the supported metal particles is 3 nm or less in the particle size of the metal particles estimated from TEM observation. Ri der particle diameter of more than 50% 1nm or less of the metal particles, wherein the carbon material is a zeolite template carbon (ZTC), metal on carbon materials.   The metal-supported carbon material according to claim 1, wherein the metal particles have an average coordination number of metal atoms determined from XAFS of 5.5 or less and an average particle diameter of 1.2 nm or less. Wherein the metal particles comprise one or more metals selected from Group 8-10 metals, metal loading carbon material according to claim 1 or 2. The metal-supported carbon material according to any one of claims 1 to 3, wherein a content of a metal to be supported is 10.3-13.3 wt% with respect to the metal-supported carbon material. Providing a carbon material having pores;
Introducing a metal complex into the carbon material;
The heat treatment of the carbon material into which the metal complex has been introduced, or reduction of the metal complex by contacting with hydrogen to obtain a metal-supported carbon material on which metal particles are supported is provided. The manufacturing method of the metal carrying | support carbon material of any one of Claims 1. The metal complex is a metal complex represented by the following chemical formula 2:
Where M is selected from Group 8-10 metals;
Where R ₁ , R ₂ Are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms,
L ₁ And L ₂ Are monodentate ligands, each independently selected from the group consisting of acetonitrile, benzonitrile, THF, diethyl sulfide, dimethyl sulfide, and pyridine; or
L ₁ And L ₂ Are linked to form a bidentate ligand, which is dicyclopentadiene, 1,5-cyclooctadiene, norbornadiene, 2,2′-bipyridine, 1,10-phenanthroline, ethylenediamine, Selected from the group consisting of N, N, N ′, N′-tetramethylethylenediamine, and trans, trans-dibenzylideneacetone:
The method for producing a metal-supported carbon material according to claim 5, wherein   The hydrogen storage material containing the metal carrying | support carbon material of any one of Claims 1-4.   The catalyst containing the metal carrying | support carbon material of any one of Claims 1-4.