JP5780589B2 - Carbon material, metal-supported carbon material using the same, and method for producing the same - Google Patents

Description

  The present invention relates to a carbon material and a metal-supported carbon material using the carbon material. More specifically, the present invention relates to a carbon material suitable for application to a hydrogen storage material or an electrode catalyst for a fuel cell, a metal-supported carbon material using the carbon material, 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 hydrogen storage materials such as hydrogen storage alloys, chemical hydrides, and adsorbent materials have been actively studied so far. Hydrogen storage alloys and chemical hydrides have a large storage capacity compared to adsorption materials and have a hydrogen storage capacity exceeding 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 in the process of occluding and releasing hydrogen in order to utilize physical adsorption, but have a problem that the amount of adsorption is small compared to hydrogen storage alloys and chemical hydrides. In recent years, hydrogen storage systems using spillover in addition to physical adsorption have 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 stored on the solid surface, it is considered that the hydrogen storage ability 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 practical use of fuel cell vehicles. In addition, the metal supported on the solid surface is mainly an expensive metal such as platinum, and only the surface portion of the metal particle contributes to spillover. Therefore, if the same amount of metal is supported, the particle size is reduced. It is essential to reduce the particle surface area as much as possible. However, there is a limit to making metal particles finer.

  Accordingly, an object of the present invention is to provide a carbon material for supporting a metal in a highly dispersed state on a solid surface, and a metal supporting material having a metal supported thereon.

  In view of the above problems, the present inventors have made extensive studies. In the process, we examined loading the metal on the surface of the carbon material as a metal complex, not as particles, and supporting the metal at the atomic level without oxidizing it. And it discovered that a metal can be easily introduce | transduced as a complex by introduce | transducing a ligand into the surface of a carbon material, and completed this invention.

  That is, the present invention is a carbon material having a phosphorus ligand, in which a phosphorus ligand is introduced into a carbon material having pores.

  According to the present invention, a metal complex can be introduced into the phosphorus ligand portion introduced into the carbon material, and therefore, the metal can be dispersed and supported on the carbon material at the atomic level. Therefore, the efficiency of hydrogen spillover is increased, and a hydrogen storage material with improved hydrogen storage efficiency can be obtained.

(A) Edge part of carbon material, (b) A carbon material in which a ligand is introduced into the carbon material, and (c) a metal-supported carbon material in which a metal atom is introduced through the ligand. is there. It is a schematic diagram showing a microporous carbon material. It is a figure showing the result of the XRD measurement of the sample manufactured by the synthesis examples 1-5. It is a figure showing the water vapor adsorption-desorption isotherm of the sample manufactured by the synthesis example 3. FIG. It is a figure showing the result of the XRD measurement of the sample manufactured in Example 6. It is a figure showing the result of the XPS measurement of the sample manufactured in Example 6. 6 is a diagram showing the results of solid ³¹ P-NMR measurement of a sample manufactured in Example 6. FIG. 6 is a diagram showing the results of solid ³¹ P-NMR measurement of a sample manufactured in Example 7. FIG. 6 is a diagram showing a hydrogen adsorption / desorption isotherm of a sample manufactured in Example 6. FIG. 6 is a diagram showing a hydrogen adsorption / desorption isotherm of a sample manufactured in Example 7. FIG. 6 is a diagram showing a hydrogen adsorption / desorption isotherm of a sample manufactured in Example 6. FIG. It is a figure showing the result of the XRD measurement of the sample manufactured in Example 8. It is a figure showing the result of the XPS measurement of the sample manufactured in Example 8. 10 is a diagram showing a hydrogen adsorption / desorption isotherm of a sample manufactured in Example 8. 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 differ from the actual ratios.

<Carbon material having phosphorus ligand>
One embodiment of the present invention is a carbon material having a phosphorus ligand, in which a phosphorus ligand is introduced into a carbon material having pores.

  As shown in FIG. 1B, the carbon material having a phosphorus ligand according to an embodiment of the present invention has a phosphorus ligand bonded to the surface of the carbon material, preferably the edge portion of the surface of the carbon material. Do it. Here, the edge of the carbon material is a surface on which the ends of the carbon condensed rings in the structure of the graphene sheet are arranged, for example, as shown in FIG.

  The carbon material according to the present embodiment is obtained by introducing a phosphorus ligand into at least a part of the surface of the carbon material. Preferably, a phosphorus ligand is introduced into at least a part of the edge portion on the surface of the carbon material. By introducing a phosphorus ligand, the metal complex can be stably coordinated to the phosphorus ligand. Therefore, the metal can be supported on the carbon material at the atomic level.

In this case, the phosphorus ligand used is not particularly limited, but is preferably PPh ¹ Ph ² (Ph ¹ and Ph ¹ may be the same or different, and are substituted or unsubstituted phenyl groups. The phosphorus ligand represented by this can be preferably used. 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.

Since P has a large d-orbit, it is easy to coordinate with a metal of group 8 to 10. In addition, if Ph ¹ and Ph ² are substituted or unsubstituted phenyl groups, they are sized to enter the pores of ZTC, which is advantageous for the reaction.

  Examples of the phosphorus ligand include, but are not limited to, diphenylphosphine, bis (3,5-dimethylphenyl) phosphine, bis (4-methoxyphenyl) phosphine, bis [4- (trifluoromethyl) phenyl] phosphine , Di (p-tolyl) phosphine, bis (3,5-di-tert-butyl-4-methoxyphenyl) phosphine, bis [3,5-bis (trifluoromethyl) phenyl] phosphine, and the like.

  The carbon material is not particularly limited as long as it has pores and edges as described above, and carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite, etc. can be used. In particular, a microporous carbon material such as zeolite-templated carbon (ZTC) can be preferably used. In ZTC, spherical thin graphene sheets are regularly connected in a three-dimensional manner, and the number of carbon atoms at the edge is relatively large. Furthermore, since it has an ultra-high surface area, it has excellent hydrogen adsorption 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 be an edge-modified carbon material in which a functional group is introduced into at least a part of the edge portion. Preferably, the carbon material is obtained by introducing a functional group having an amidine structure into at least a part of the edge portion of the carbon material. At this time, a phosphorus ligand is bonded to the functional group having the amidine structure.

  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 ¹ , R ² and R ³ 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 ¹ and R ² may combine to form a ring, or R ² and R ³ 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 ¹ and R ² are combined to form a ring, or when R ² and R ³ 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.

The edge-modified carbon material into which the functional group having the amidine structure is introduced, the carbon material having a phosphorus ligand, or the metal-supported carbon material described later 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.

  The edge-modified carbon material into which the functional group having the amidine structure is introduced, the carbon material having a phosphorus ligand, or the metal-supported carbon material to be described later is adsorbed as the two-dimensional stacking regularity is less as a structural feature. Strength increases. 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.

Further, the edge-modified carbon material into which the functional group having the amidine structure is introduced has a relative pressure (P / P ₀ ) showing a maximum value of the inclination of the water vapor adsorption isotherm at 25 ° C. of 0.70 or less. It is preferable. If it is the said range, the hydrophilicity of the surface of a carbon material is high, and functionality can be provided to a carbon material.

  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.

(Method for producing edge-modified carbon material)
The edge-modified carbon material into which the functional group having an amidine structure is introduced includes a step of preparing a carbon material having an edge (carbon material precursor), and reacting the carbon material with an azo compound having an amidine structure. And a step of introducing a functional group having an amidine structure into the edge of the carbon material.

  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-supported 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. However, as described later, the removal of the template can be performed simultaneously with the reaction for introducing the functional group having an amidine structure. Therefore, an azo compound having an amidine structure is obtained using a composite in which carbon is deposited on a porous material as a raw material. An edge-modified carbon material may be produced by reacting with a compound.

  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 diameter. 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. The heating temperature is more preferably 450 to 1100 ° C, further preferably 500 to 900 ° C. 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 about 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 about 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.

  Next, a functional group having an amidine structure is introduced into the edge of the carbon material thus obtained. Edges on the surface of the carbon material are active surfaces, and various amidine structures can be introduced using a polymerization initiator or the like that can generate radicals. The method for introducing a functional group having an amidine structure at the edge of the carbon material is not particularly limited. For example, there is a method comprising a step of reacting a carbon material having an edge portion with an azo compound having an amidine structure (for example, a water-soluble azo polymerization initiator) to introduce a functional group having an amidine structure at the edge of the carbon material. It 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.

  In addition, normally, when preparing ZTC, it is necessary to prepare a composite of zeolite and carbon as a precursor of ZTC and then to remove the zeolite by treatment with hydrofluoric acid. The step of introducing the 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.

  When an amidine functional group is introduced into the edge portion of the carbon material, various chemical structures can be further introduced into the functional group portion. At this time, by introducing a phosphorus ligand into the amidine functional group portion. The metal complex described later can be coordinated stably.

  Since the functional group having an amidine structure is a strong base and exhibits nucleophilicity, a phosphorus ligand can be introduced into the carbon material using the amidine structure as a base point. Thereafter, as described later, a metal complex containing a metal serving as a catalyst is introduced into the phosphorus ligand. In this reaction, the ligand of the metal complex can proceed by a ligand exchange reaction in which the phosphorus ligand having a strong coordination power is replaced. As a result, a bidentate ligand composed of a phosphorus ligand and a strongly basic amidine structure is formed. Accordingly, a phosphorus atom and a nitrogen atom are simultaneously chelated to the metal atom, and the metal can be supported as a stable complex. If the metal complex can be supported in this way, it becomes possible to disperse the metal at the atomic level instead of the particles.

  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.

  The conditions for reacting the edge-modified carbon material with the phosphorus compound are not particularly limited. Preferably, the edge-modified carbon material that has been dried by heating under vacuum and allowed to cool is reacted with a phosphorus compound, preferably in the presence of an amine, with nitrogen substitution. The reaction temperature and reaction time are not particularly limited. Preferably, the edge-modified 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.

  The amount of the phosphorus compound used is not particularly limited, but is preferably 0.5 to 100 mol, more preferably 1 to 10 mol, relative to 1 mol of the functional group having an amidine structure bonded to the carbon material. If it is the said range, reaction can advance efficiently.

  On the other hand, a phosphorus ligand can be directly introduced into a carbon material that is not edge-modified. As the phosphorus compound for introducing the phosphorus ligand and the reaction conditions for reacting the phosphorus compound with the carbon material, the same conditions as in the case of the edge-modified carbon material described above can be adopted. When a carbon material that is not edge-modified is used, it is considered that the phosphorus compound is introduced into the carbon material by reacting with oxygen-containing functional groups on the surface of the carbon material. For this reason, it is considered that not only ZTC with a high ratio of edge portions but also a carbon material with a relatively small ratio of edge portions can efficiently introduce a phosphorus ligand. In addition, since the step of edge modification can be omitted, the cost can be reduced.

<Metal-supported carbon material>
One embodiment of the present invention is a metal-supported carbon material in which a group 8-10 metal is coordinated to a phosphorus ligand in the above carbon material having a phosphorus ligand.

  As shown in FIG. 1C, the metal-supported carbon material according to this embodiment is supported by a metal of group 8 to 10 coordinated as a complex via a ligand on the surface of the carbon material. Has been. That is, the metal is supported not as particles but as a complex. By doing so, the metal can be dispersed at the atomic level without being oxidized, so that a more efficient spillover is possible.

  Preferably, the metal is supported in a carbon material within a concentration range of 0.01 to 10 wt%. 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 10 wt% or less, the pore function is maintained and a high BET surface area can be obtained.

  It is preferable that the metal to carry | support is 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.

In the metal-supported carbon material according to the present embodiment, the volume occupied by the micropores 2a is preferably 1.0 cm ³ / g or more in a state where a metal is supported. The volume occupied by the micropores 2a is more preferably 1.2 cm ³ / g or more, and further preferably 1.5 cm ³ / g or more. Moreover, it is preferable that a BET surface area is 1500 m < ² > / g or more in the state which carry | supported the metal. The BET surface area, for example 2000 m ² / g or more, preferably 2500 m ² / g or more, more preferably 3000 m ² / g or more, and more preferably BET surface area of 3500 m ² / g or more. When the volume occupied by the micropores is 1.0 cm ³ / g or more, or the BET surface area is 1500 m ³ / g or more, sufficient hydrogen storage performance can be obtained.

  Further, it is preferable that the metal-supported carbon material has as few diffraction peaks as possible in the X-ray diffraction pattern obtained when powder X-ray diffraction measurement is performed, which usually shows a two-dimensional stacking regularity around 26 °.

  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. Further, dissociative adsorption of hydrogen molecules is promoted and hydrogen storage capacity can be improved as compared with the case where particulate metal is supported. Therefore, when the metal-supported carbon material is used as a hydrogen storage material, highly efficient storage and release of hydrogen becomes possible.

(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 obtaining a carbon material having a phosphorus ligand by reacting the carbon material with a phosphorus compound, and the phosphorus coordination. Reacting a carbon material having a child with a group 8-10 metal compound to coordinate a group 8-10 metal to the phosphorus ligand.

  Here, the step of preparing the carbon material having pores and the step of obtaining the carbon material having a phosphorus ligand by reacting the carbon material with a phosphorus compound are the same as described above, and thus the description thereof is omitted. 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 the phosphorus ligand and the metal complex are reacted under reflux in a nitrogen atmosphere. 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.

<Hydrogen storage material>
The above-mentioned metal-supported carbon material 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.

  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.

1. 1. Introduction of amidine structure to microporous carbon material 1-1. Sample Preparation <Reference Example 1: NaY-PFA-P7 (1) -H9 (3)>
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, and the zeolite as a template was dissolved and removed to take out a microporous carbon material (MPC). The sample thus obtained was named NaY-PFA-P7 (1) -H9 (3).

<Synthesis Example 1>
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 0.15 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.

<Synthesis Example 2>
An edge-modified microporous carbon material was obtained in the same manner as in Synthesis Example 1 except that VA-044 was added to 0.50 wt% with respect to the total weight of the reaction solution.

<Synthesis Example 3>
An edge-modified microporous carbon material was obtained in the same manner as in Synthesis Example 1 except that VA-044 was added to 2.50 wt% with respect to the total weight of the reaction solution.

<Synthesis Example 4>
VA-044 was added so as to be 2.50 wt% with respect to the total weight of the reaction solution, and the reaction was performed for 1 hour after the temperature of hydrofluoric acid reached 60 ° C. Similarly, an edge-modified microporous carbon material was obtained.

<Synthesis Example 5>
Synthesis Example 1 except that the carbon / zeolite composite prepared 15 months ago was used and VA-044 was added to 2.50 wt% with respect to the total weight of the reaction solution. Similarly, an edge-modified microporous carbon material was obtained.

1-2. Evaluation The powder X-ray diffraction measurement of the microporous carbon material synthesized in Synthesis Examples 1 to 5 and Reference Example 1 was performed using XRD-6100 manufactured by Shimadzu Corporation, and the radiation source was Cu-Kα, voltage 30 kV, and current 20 mA. It was. The BET surface area was measured using BELSORP mini manufactured by Nippon Bell Co., Ltd. at a temperature of −196 ° C. by a multipoint method. The water vapor adsorption isotherm was measured at a temperature of 25 ° C. using BELSORP MAX manufactured by Nippon Bell.

Table 1 shows the pore structure of the sample calculated from the BET surface area S _BET , nitrogen content (N / C), and nitrogen adsorption / desorption measurement results of the microporous carbon materials synthesized in Synthesis Examples 1 to 5 and Reference Example 1. Shown in Here, _VTotal , _Vmicro , and _Vmeso represent the volume occupied by all pores, the volume occupied by micropores, and the volume occupied by mesopores, respectively. The results of measurement using a powder X-ray diffractometer (XRD) indicating the presence or absence of a long-period ordered structure are summarized in FIG.

From the results of Table 1 and FIG. 3, as the charged concentration of VA-044 is increased and when the reaction time is increased from 1 hour to 6 hours, the N / C ratio increases and more functional groups having an amidine structure are introduced. You can see that Further, the more functional groups having an amidine structure are introduced, the BET surface area tends to decrease. In Synthesis Example 3, the amount is reduced by 17% compared to Reference Example 1. However, it was found that a sufficiently large BET surface area of 2000 m ² / g or more was maintained even when a functional group having an amidine structure was introduced.

  As shown in FIG. 3, in the X-ray diffraction patterns of the samples of Synthesis Examples 1 to 5, a peak indicating a long-period regular structure near 2θ = 6 ° is clearly observed, and the carbon network surface is 2θ = 20 to 30 °. The intensity of the peak derived from the lamination of was small. From this, it was confirmed that the ordered structure of the microporous carbon material (MPC) was maintained in the obtained sample.

  The ratio of the edge of ZTC is determined from the mass of ZTC and the H / C ratio, and even if it is assumed that the edges are all radicals, the concentration of VA-044 is 0.15 wt% in order to react all the radicals of the edges. Although considered to be sufficient, when the synthesis examples 1 to 3 are compared, N / C increases as the concentration of VA-044 increases. Furthermore, when Synthetic Example 3 and Synthetic Example 4 having different reaction times at the same concentration are compared, it can be seen that N / C increases as the reaction time increases. This is because when VA-044 is excessive or the reaction time is long, not only the reaction between the radical derived from VA-044 and the radical site of ZTC, but also the hydrogen at the edge of ZTC is attracted to the radical derived from VA-044. It is considered that the mechanism by which the radical site generated as a result of ZTC is recombined with the radical derived from VA-044 is also involved.

  FIG. 4 shows the water vapor adsorption / desorption isotherms of Reference Example 1 and Synthesis Example 3. When the pore diameter is the same, the smaller the relative pressure at which the amount of adsorption increases rapidly, the more hydrophilic the material surface. Comparing the water vapor adsorption isotherms of Reference Example 1 and Synthesis Example 3, both rises are about the same at about 0.5 relative pressure. This is considered to be due to the influence of oxygen-containing functional groups contained in a sample in a certain amount as shown in the elemental analysis results in Table 1 in addition to the effect of introducing hydrophilic functional groups.

2. 2. Introduction of atomic order platinum into edge-modified microporous carbon material 2-1. Sample Preparation <Example 6>
(Introduction reaction of phosphorus ligand into edge-modified microporous carbon material)
Reaction was performed according to the following formula.

  ZTC into which an amidine structure was introduced was prepared by the same procedure as in Synthesis Example 3.

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 under vacuum 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 elemental analysis results of this sample are shown in Table 2 below. The N / C of ZTC-VA044-PPh ₂ calculated from the weight change of the sample before and after the reaction from ZTC-VA044 to ZTC-VA044-PPh ₂ was in good agreement with the N / C value obtained by elemental analysis.

  The phosphorus content measured by inductively coupled plasma (ICP) emission spectroscopy was 2.53 wt%. As a result of calculating from the contents of nitrogen and phosphorus, it was found that a phosphorus ligand was introduced into a functional group having an amidine structure of 82.76%. Here, the content of phosphorus 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.

(Introduction of platinum complex into edge-modified microporous carbon material with phosphorus ligand)
Reaction was performed 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 and then filtered through a membrane filter (0.1 μm, H010A047A manufactured by ADVANTEC), washed with 100 ml of acetonitrile and subsequently with 100 ml of diethyl ether, and then dried under vacuum. (100 ° C., 6 hours). This sample represents the _{ZTC-VA044-PPh 2 -PtMe 2} . The yield was 0.37g.

After quantitative analysis of phosphorus and platinum contained in ZTC-VA044-PPh ₂ -PtMe ₂ which is a sample prepared in Example 6, the sample was decomposed by alkali melting into a solution, and then inductively coupled plasma manufactured by SII Nanotechnology Inc. (ICP) The emission spectroscopic analyzer was used. The phosphorus contained in the sample was 1.62 wt%, and platinum was 11.1 wt%.

Also, BET surface area of the ZTC-VA044-PPh ₂ and _{ZTC-VA044-PPh 2} -PtMe 2 calculated by the nitrogen adsorption-desorption measurements were respectively 1910m ² / g and 1550 g / ^{m 2.}

<Example 7>
(Introduction reaction of phosphorus ligand into microporous carbon material)
Example 6 (excluding phosphorus ligands on edge-modified microporous carbon material) except that a microporous carbon material prepared by the same procedure as in Reference Example 1 was used instead of ZTC into which the amidine structure was introduced. A carbon material having a phosphorus ligand was obtained by the same procedure as in the introduction reaction. This sample represents the ZTC-PPh _2.

Furthermore, in place of ZTC-VA044-PPh ₂ except that ZTC-PPh ₂ prepared above was used, Example 6 (platinum complex to edge-modified microporous carbon material having a phosphorus ligand) A carbon material having a phosphorus ligand was obtained in the same manner as in the introduction). This sample represents the _{ZTC-PPh 2} -PtMe 2.

After quantitative analysis of phosphorus and platinum contained in the sample ZTC-PPh ₂ -PtMe ₂ prepared in Example 7, the sample was decomposed into a solution by melting with an alkali, and then inductively coupled plasma (ICP) manufactured by SII Nanotechnology Inc. was used. ) Using an emission spectroscopic analyzer. The phosphorus contained in the sample was 1.48 wt%, and platinum was 10.3 wt%.

The BET surface areas of ZTC-PPh ₂ and ZTC-PPh ₂ -PtMe ₂ calculated by nitrogen adsorption / desorption measurement were 1930 m ² / g and 1860 g / m ² , respectively.

<Comparative Example 1>
In the same procedure as in Reference Example 1, a microporous carbon material (MPC) was obtained.

Next, as a Pt aqueous solution, 6.7 ml of a 0.096 wt% aqueous solution A of diamine dinitroplatinum [Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ], which is a compound containing Pt, and borohydride that is an aqueous reducing agent solution An aqueous solution B of sodium (66.7 ml) was prepared, and solutions A and B were cooled to 0 ° C. The concentrations of solutions A and B were calculated so that the supported amount of platinum was 3.8 wt% with respect to the obtained MPC. Next, 100 mg of MPC was added to the solution A at 0 ° C., and stirred at 0 ° C. for 30 minutes in a reduced pressure atmosphere. Next, this was centrifuged, mixed with solution B at 0 ° C., and stirred at 0 ° C. for 10 minutes to reduce Pt to produce platinum nanoparticles. Finally, the operation of filtering the MPC supporting platinum nanoparticles and washing with pure water was repeated several times, followed by vacuum drying at 150 ° C. for 6 hours to obtain MPC supporting platinum. This sample is denoted as Pt / ZTC.

<Comparative Example 2>
After the carbon material prepared in Reference Example 1 was dried by heating under vacuum, a (1,5-cyclooctadiene) dimethylplatinum (II) complex was injected and vacuum impregnated, impregnated with the platinum complex, and the carbon material ZTC-PtMe ₂ COD was obtained. The amount of platinum contained in this sample was 13.3 wt%.

2-2. Evaluation The sample prepared in Example 6 was subjected to XRD measurement and hydrogen adsorption / desorption measurement. XRD measurement was performed in the same manner as in 1-2 above.

FIG. 5 shows the X-ray diffraction patterns of the samples prepared in Example 6, ZTC-VA044-PPh ₂ and ZTC-VA044-PPh ₂ -PtMe ₂ . For comparison, an X-ray diffraction pattern of a sample in which ZTC not having an amidine structure and an amidine structure were introduced was shown. As shown in FIG. 5, the X-ray diffraction patterns of ZTC-VA044-PPh ₂ and ZTC-VA044-PPh ₂ -PtMe ₂ are weak compared to the X-ray diffraction pattern of MPC of Reference Example 1, but 2θ indicated by 2X. = 6 ° shows a peak, and the peak intensity at 2θ = 20-30 ° is small. This shows that the sample obtained in Example 6 retains the regular structure of MPC. In addition, no peak derived from zero-valent platinum was confirmed.

FIG. 6 shows the XPS spectrum of ZTC-VA044-PPh ₂ -PtMe ₂ obtained in Example 6. Peaks derived from divalent platinum were observed around 72.3 eV and 75.9 eV. From the results of FIGS. 5 and 6, it was confirmed that divalent platinum was supported on ZTC. The XPS spectrum was measured using ESCA-3400 manufactured by KRATOS, and the radiation source was Mg-Kα, the voltage was 10 kV, and the current was 10 mA.

7 and 8 show the solid ³¹ P-NMR spectrum of the sample obtained in Example 6. FIG. The solid ³¹ P-NMR spectrum (FIG. 8) of ZTC-VA044-PPh ₂ not carrying a Pt complex shows one peak at 21.08 ppm, whereas in ZTC-VA044-PPh ₂ -PtMe ₂ It can be seen that the peak is split into two, and Pt is supported as a complex on a part of the phosphorus ligand contained in the sample. The integration ratio of the two peaks was 3.1 (48.79 ppm): 84.7 (21.39 ppm). From this integration ratio and the amount of platinum contained in the sample (11.1 wt%), the proportion of platinum coordinated to the phosphorus ligand is 3.2% based on the amount of platinum contained in the sample. Can be estimated.

On the other hand, as shown in FIG. 8, when the solid ³¹ P-NMR spectrum of the sample obtained in Example 7 was compared with the sample of Example 6, ZTC-PPh ₂ was in a position different from ZTC-VA044-PPh _2. It turns out that the peak top is shown. This suggests that in ZTC-PPh ₂ , the atom to which the phosphorus atom of the introduced phosphorus ligand is bonded is different in both. In ZTC-VA044-PPh ₂ , the generation of oxygen-containing functional groups on the ZTC surface is suppressed by reacting radicals during the removal of zeolite by the hydrofluoric acid treatment at the end of ZTC synthesis. Therefore, ZTC-VA044 has a small amount of oxygen-containing functional groups, and it is considered that amidine reacted with chlorodiphenylphosphine. However, in the reaction of ZTC-PPh ₂ and chlorodiphenylphosphine, it is considered that the oxygen-containing functional group on the surface of ZTC and chlorodiphenylphosphine reacted. In ZTC-PPh ₂ -PtMe ₂ after supporting the platinum complex, the peak slightly shifted to the high magnetic field side.

  In order to evaluate the hydrogen storage capacity of the obtained sample, a pressure-composition isotherm (PCT line) was obtained for the sample of Example 6 according to the Siebels method (capacity method, JIS H 7201). The hydrogen storage capacity was measured using a compression coefficient defined by the National Institute of Standards and Technology (NIST). The measurement accuracy depends on the filling amount of the sample. At least 1 g or more was charged, and the above synthesis scheme was repeated as necessary to prepare the required amount. The sample was weighed and placed in a pressure-resistant sample tube for measurement, and was evacuated at 100 ° C. for 4 hours to release the gas remaining in the sample tube, and measurement was performed after obtaining an origin where hydrogen was not occluded. The measurement temperature was 25 ° C, 70 ° C, and 100 ° C. The measurement order was measured at 70 ° C. after measurement at 25 ° C. with a new sample. Then, it measured at 100 degreeC with the new sample. After measuring the hydrogen storage capacity, the pressure was reduced to atmospheric pressure, and the hydrogen release amount was confirmed. The measurement results are shown in FIG. In FIG. 9, the filled plot is the data on the adsorption side, and the white plot is the data on the discharge side.

From the results of FIG. 9, it was found that the hydrogen adsorption amount of ZTC-VA044-PPh ₂ -PtMe ₂ prepared in Example 6 significantly increased as the temperature increased. In FIG. 9, H ₂ / Pt is the molar ratio of adsorbed hydrogen molecules and supported platinum at each measurement point. As shown in FIG. 9, in the sample of Example 6, the value of H ₂ / Pt is a maximum value of 4.82, and not only the hydrogen molecules are dissociated and adsorbed on the platinum complex, but also the dissociated hydrogen atoms flow out. (Spillover).

The sample of Example 7 was measured using the hydrogen storage capacity in the same manner as described above. The sample was evacuated at 100 ° C. for 6 hours to release the gas remaining in the sample tube, and the measurement was performed after obtaining an origin where hydrogen was not occluded. The measurement temperature was 25 ° C, 70 ° C, and 100 ° C. The measurement order was measured with a new sample at 25 ° C. and subsequently at 70 ° C. and then at 100 ° C. (upper FIG. 10). Thereafter, measurement was performed on a new sample at 100 ° C. (in FIG. 10, in FIG. 10, solid plots are data on the adsorption side, and white plots are data on the discharge side). As shown in FIG. 10, in the sample of Example 7, the maximum H ₂ / Pt value was 4.65. Therefore, even when a carbon material that is not edge-modified is used, a metal complex can be supported on the phosphorus ligand as in the case of using a carbon material that is edge-modified with amidine, and excellent hydrogen adsorption characteristics can be obtained. It was confirmed that

With respect to the sample of Comparative Example 2, the hydrogen storage capacity was measured at 25 ° C., 70 ° C., and 100 ° C. in the same manner as the sample of Example 6 above. Similar to the sample of Example 6 above, the amount of hydrogen adsorption increased with increasing temperature (not shown). The value of H ₂ / Pt at the maximum value of the adsorption amount is 1.67, and it is considered that 1.7 molecules of hydrogen are adsorbed and dissociated with respect to one molecule of the platinum complex.

FIG. 11 shows the amount of hydrogen adsorption per weight of the sample measured at 25 ° C. for ZTC-VA044-PPh ₂ -PtMe ₂ prepared in Example 6, ZTC of Reference Example 1, and Pt / ZTC of Comparative Example 1. FIG. In FIG. 11, the filled plot is the data on the adsorption side, and the white plot is the data on the discharge side. The measurement conditions are the same as in Example 6 except for the temperature conditions. For comparison, the results of the sample of Example 6 measured at a temperature of 25 ° C. are also shown. From the results of FIG. 11, it can be seen that the amount of hydrogen adsorption per weight of the sample of Example 6 is improved as compared with the samples of Reference Example 1 and Comparative Example 1.

  Furthermore, in the samples of Examples 6 and 7, the hydrogen adsorption amount increased with increasing temperature (FIGS. 9 and 10), whereas in the samples of Reference Example 1 and Comparative Example 1, the hydrogen adsorption amount increased at high temperatures. There was a tendency to decrease (not shown).

  Thus, it has been clarified that when the metal complex is supported on the carbon material, the hydrogen storage capacity is greatly improved as compared with the case where the metal complex is not contained or the case where the particulate metal is supported.

3. 3. Introduction of atomic-order palladium into edge-modified microporous carbon material 3-1. Sample Preparation <Example 8>
(Introduction reaction of phosphorus ligand into edge-modified microporous carbon material)
In the same manner as in Example 6, chlorodiphenylphosphine phosphorus ligand were introduced into ZTC introducing the amidine structure (ZTC-VA044), were prepared ZTC-VA044-PPh _2.

(Introduction of palladium complex into edge-modified microporous carbon material with phosphorus ligand)
Reaction was performed according to the following formula.

After 19.8 mg of ZTC-VA044-PPh ₂ prepared above was vacuum-heated and dried at 150 ° C. overnight, 15 ml of palladium chloride / acetonitrile solution was vacuum impregnated and stirred at 80 ° C. for 3 hours. Here, a palladium chloride / acetonitrile solution prepared by adding 20 ml of acetonitrile to 25.3 mg of palladium chloride under a nitrogen atmosphere and heating to about 80 ° C. to dissolve palladium chloride was used. Thereafter, the reaction solution was filtered with a membrane filter, washed with 200 ml of acetonitrile, further washed with 200 ml of THF, and then vacuum-heated and dried at 150 ° C. for 6 hours. This sample represents the _{ZTC-VA044-PPh 2 -PdCl 2} . The yield was 17.4 mg.

3-2. Evaluation FIG. 12 shows the XRD measurement results of the ZTC-VA044-PPh ₂ -PdCl ₂ prepared above. The apparatus and measurement conditions are the same as those described above. As shown in FIG. 12, a peak indicating a long-period regular structure in the vicinity of 2θ = 6 ° is observed, indicating that the MPC regular structure is maintained. Further, a peak derived from zero-valent Pd particles was observed in the vicinity of 2θ = 40 °.

13 shows a _{ZTC-VA044-PPh} 2 XPS measurements of -PdCl ₂ prepared above. The apparatus and measurement conditions are the same as those described above. Peaks derived from zero-valent palladium are observed at 340.4 eV and 335.2 eV. On the other hand, a peak derived from divalent palladium was observed in the vicinity of 337.5 eV, which is considered to be due to non-coordinated PdCl ₂ in addition to the divalent Pd complex coordinated to the phosphorus ligand. It is done.

FIG. 14 shows the hydrogen adsorption / desorption measurement results of ZTC-VA044-PPh ₂ -PdCl ₂ produced as described above. The measurement temperatures were 100 ° C., 120 ° C., and 140 ° C. The measurement order was as follows: first time: 100 ° C., second time: 120 ° C., third time: 150 ° C., fourth time: 100 ° C. In FIG. 14, the solid plot is the data on the adsorption side, and the white plot is the data on the discharge side.
It can be seen that the amount of adsorption increases as the temperature rises, and the maximum value of the amount of adsorption is about 0.2 wt%. Therefore, it has been clarified that ZTC carrying a Pd complex can obtain a high hydrogen storage capacity as in the case of carrying a Pt complex.

  In addition, the amount of adsorption increases as the temperature rises, and since desorption of hydrogen can be confirmed especially in the third (150 ° C.) and fourth (100 ° C.) measurements, it mainly contributes to hydrogen adsorption. It is thought that it is not a zero-valent Pd particle but a divalent Pd complex.

  Furthermore, even when measured four times, the sample is unlikely to deteriorate, which is presumably because the Pd complex has good thermal stability and lifetime.

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

Claims (7)

Ri Na and phosphorus ligand is introduced into the carbon material having pores,
A carbon material having a phosphorus ligand, wherein a functional group having an amidine structure is introduced into at least a part of an edge of a carbon material having pores, and a phosphorus ligand is bonded to the functional group having the amidine structure. . The phosphorus ligand according to claim ¹ , wherein the phosphorus ligand is PPh ¹ Ph ² (Ph ¹ and Ph ² may be the same or different, and are substituted or unsubstituted phenyl groups). Carbon material with a ligand.   The carbon material having a phosphorus ligand according to claim 1 or 2, wherein the carbon material is zeolite-templated carbon (ZTC). The carbon material having a phosphorus ligand according to any one of claims 1 to 3, wherein the functional group having the amidine structure is at least one selected from functional groups represented by the following chemical formula 1:
In the formula, R ¹ , R ² and R ³ 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 ¹ and R ² may combine to form a ring, or R ² and R ³ may combine to form a ring. A metal-supported carbon material obtained by coordinating a group 8-10 metal to the phosphorus ligand of the carbon material having the phosphorus ligand according to any one of claims 1 to 4 . Providing a carbon material having pores;
Reacting the carbon material with a phosphorus compound to obtain a carbon material having a phosphorus ligand;
Reacting the carbon material having the phosphorus ligand with a group 8-10 metal compound to coordinate the group 8-10 metal to the phosphorus ligand;
I have a,
Preparing a carbon material having the pores,
The carbon material precursor is reacted with an azo compound having the amidine structure comprises obtaining the carbon material precursor edge modified carbon material by introducing a functional group having an amidine structure edges, the metallic supporting carbon material Production method. A hydrogen storage material comprising the metal-supported carbon material according to claim 5 or the metal-supported carbon material produced by the method according to claim 6 .