WO2016013245A1 - Catalyst material and method for producing same - Google Patents

Catalyst material and method for producing same Download PDF

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Publication number
WO2016013245A1
WO2016013245A1 PCT/JP2015/056440 JP2015056440W WO2016013245A1 WO 2016013245 A1 WO2016013245 A1 WO 2016013245A1 JP 2015056440 W JP2015056440 W JP 2015056440W WO 2016013245 A1 WO2016013245 A1 WO 2016013245A1
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Prior art keywords
catalyst material
dispersion
carbon
fine particles
carbon nanofibers
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PCT/JP2015/056440
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French (fr)
Japanese (ja)
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新井　進
貢 上島
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日本ゼオン株式会社
国立大学法人信州大学
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Priority to JP2016535809A priority Critical patent/JPWO2016013245A1/en
Publication of WO2016013245A1 publication Critical patent/WO2016013245A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold
    • B01J35/58—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
    • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
    • C07C51/23—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups
    • C07C51/235—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups of —CHO groups or primary alcohol groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C59/00—Compounds having carboxyl groups bound to acyclic carbon atoms and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
    • C07C59/01—Saturated compounds having only one carboxyl group and containing hydroxy or O-metal groups
    • C07C59/10—Polyhydroxy carboxylic acids
    • C07C59/105—Polyhydroxy carboxylic acids having five or more carbon atoms, e.g. aldonic acids

Definitions

  • the present invention relates to a catalyst material and a method for producing the same, and more particularly to a catalyst material containing gold fine particles and a method for producing the catalyst material.
  • Gold can be made into fine particles, such as low-temperature CO oxidation reaction, propylene vapor phase one-step epoxidation reaction, low-temperature water gas shift reaction, direct hydrogen peroxide synthesis reaction from oxygen and hydrogen, and partial oxidation reaction of hydrocarbons. In such reactions, it is known to exhibit excellent catalytic activity.
  • noble metals such as gold are expensive, they are required to be recovered after use as a catalyst.
  • catalytic materials in which gold fine particles are supported on a carrier have been studied, and in addition, technologies for exerting excellent catalytic activity on the catalytic materials have been widely studied. (For example, see Patent Documents 1 and 2).
  • Patent Document 1 discloses a catalyst material in which metal particles such as gold fine particles are supported on a carrier containing carbon, and at least a part of the metal particles has a planar region (for example, a maximum width of 3 to 100 nm), It has been reported that it exhibits excellent surface activity and, for example, exhibits excellent effects as a catalyst for treating nitrate nitrogen.
  • Patent Document 2 as a method for obtaining a catalyst material by dispersing and immobilizing gold fine particles on a support, gold-chalcogen ions formed by adding a chalcogenide to a gold compound solution are brought into contact with the support to form a support.
  • a method is disclosed in which gold chalcogenide is precipitated on the surface of the carrier by adsorbing gold-chalcogen ions, and then gold fine particles are precipitated on the surface of the carrier by separating and heating the carrier.
  • this method makes it possible to support gold fine particles on an acidic carrier, which has been difficult with the conventional method, and that the catalyst material obtained by this method has excellent catalytic activity.
  • Patent Documents 1 and 2 fail to exhibit a sufficiently satisfactory catalytic activity for the catalyst material.
  • Patent Documents 1 and 2 mainly focus on the gold fine particles and the supporting method thereof, and the carrier supporting the gold fine particles has not been sufficiently studied. That is, the above-described conventional technology has room for improvement, particularly in that the catalyst material exhibits excellent catalytic activity by improving the carrier supporting the gold fine particles.
  • an object of this invention is to provide the catalyst material which was carrying
  • Another object of the present invention is to provide a method for producing a catalyst material carrying gold fine particles and having excellent catalytic activity.
  • the inventors of the present invention have made extensive studies to achieve the above object.
  • the inventors of the present invention may further improve the catalytic activity of the catalyst material by using carbon nanofibers having a predetermined average diameter as the support in the catalyst material in which the gold fine particles are supported on the support.
  • the present invention has been completed by finding out what can be done.
  • the present invention aims to advantageously solve the above-mentioned problems, and the catalyst material of the present invention is such that gold fine particles are supported on carbon nanofibers having an average diameter (Av) of 5 nm or less.
  • Av average diameter
  • a catalyst material containing carbon nanofibers having an average diameter of 5 nm or less and gold fine particles supported on the carbon nanofibers has excellent catalytic activity.
  • fiber refers to those having an aspect ratio of 10 or more.
  • the “average diameter of carbon nanofibers” can be determined by measuring the diameter (outer diameter) of 100 carbon nanofibers selected at random using a transmission electron microscope.
  • the average diameter (Av) and the standard deviation ( ⁇ ) of the diameter satisfy the relational expression: 0.20 ⁇ (3 ⁇ / Av) ⁇ 0.60.
  • a carbon nanotube is preferred. This is because the catalytic activity of the catalyst material can be further improved by using carbon nanotubes having 3 ⁇ / Av of more than 0.20 and less than 0.60.
  • “average diameter (Av) of carbon nanotubes” and “standard deviation of carbon nanotube diameter ( ⁇ : sample standard deviation)” are carbons selected at random using a transmission electron microscope, respectively. It can be obtained by measuring the diameter (outer diameter) of 100 nanotubes.
  • the carbon nanofibers are preferably subjected to gas phase plasma treatment. This is because the catalytic activity of the catalyst material can be further improved by using the carbon nanofibers subjected to the gas phase plasma treatment as a carrier.
  • the average particle diameter of the gold fine particles is 2 nm or more and 10 nm or less. This is because if the average particle size of the gold fine particles supported on the carbon nanofibers is 2 to 10 nm, the catalytic activity of the catalyst material can be further improved.
  • the “average particle diameter of gold fine particles” is the particle diameter based on images of 100 gold fine particles carried on carbon nanofibers selected at random using a transmission electron microscope. (The maximum length among the lengths of line segments connecting two points on the outer edge of each particle) can be measured and determined.
  • the manufacturing method of the catalyst material of this invention is a manufacturing method of any of the catalyst materials mentioned above, Comprising: Average diameter (Av ) Is a process of dispersing carbon nanofibers of 5 nm or less in a solvent in the presence of an ionic surfactant and a high molecular weight surfactant in a solvent by a dispersion treatment that provides a cavitation effect or a crushing effect (carbon nanofiber dispersion step ) Is one of the major features.
  • a catalyst material can be obtained.
  • supported the gold fine particle and was excellent in catalyst activity can be provided.
  • supported the gold fine particle and was excellent in catalytic activity can be provided.
  • 4 is a TEM image of the catalyst material of Example 2. 4 is a TEM image of the catalyst material of Example 3.
  • the catalyst material of the present invention is excellent in catalytic activity and can be suitably used as a catalyst material (for example, an oxidation catalyst material) for various reactions.
  • the catalyst material of this invention can be prepared using the manufacturing method of the catalyst material of this invention, for example.
  • the catalyst material of the present invention includes carbon nanofibers having an average diameter of 5 nm or less as a support and gold fine particles present on the surface of the carbon nanofibers.
  • the catalyst material of the present invention is used as a catalyst for a chemical reaction in a state where gold fine particles having a very fine structure are supported on the surface of a carrier, not as they are.
  • the carbon nanofiber surface is excellent in affinity with the gold fine particles, and the gold fine particles are firmly supported on the carbon nanofiber surface, so that the gold fine particles remain supported on the carbon nanofiber surface after the chemical reaction.
  • the catalyst material can be easily recovered.
  • the catalyst material of the present invention is used, the reactivity of a chemical reaction such as an oxidation reaction can be improved, that is, the catalyst material of the present invention is excellent in catalytic activity.
  • the reason why the catalytic activity of the catalyst material is improved by using carbon nanofibers having an average diameter of a specific value or less as a carrier for supporting gold fine particles is not clear, but the above-mentioned carbon nanofiber surface and gold fine particles are good.
  • the average particle diameter of the gold fine particles formed on the carbon nanofiber is also reduced by the small average diameter of the carbon nanofiber.
  • the carbon nanofibers used as a carrier for supporting gold fine particles carbon nanotubes or carbon nanofibers having an average diameter of 5 nm or less can be used, and carbon nanotubes having an average diameter of 5 nm or less should be used. Is preferred.
  • the carbon nanofibers are preferably carbon nanofibers that have been subjected to oxidation treatment, in particular, gas phase plasma treatment. That is, as the carbon nanofiber used for the catalyst material, a carbon nanotube having an average diameter of 5 nm or less and subjected to gas phase plasma treatment is particularly preferable.
  • the CNT used for the catalyst material is not particularly limited as long as the average diameter is 5 nm or less, and single-walled carbon nanotubes and / or multi-walled carbon nanotubes can be used. It is preferably a carbon nanotube of up to 5 layers, and more preferably a single-walled carbon nanotube. This is because if single-walled carbon nanotubes are used, the average particle diameter of the gold fine particles can be made smaller than when multi-walled carbon nanotubes are used, and the catalytic activity of the catalyst material can be improved satisfactorily.
  • a CNT having a ratio (3 ⁇ / Av) of a value (3 ⁇ ) obtained by multiplying the standard deviation ( ⁇ ) of the diameter by 3 with respect to the average diameter (Av) is more than 0.20 and less than 0.60. It is preferable to use CNTs with 3 ⁇ / Av exceeding 0.25, and it is even more preferable to use CNTs with 3 ⁇ / Av exceeding 0.50. This is because if 3CNT / Av is more than 0.20 and less than 0.60, the average particle size of the gold fine particles can be reduced and the catalytic activity of the catalyst material can be further improved.
  • the average diameter (Av) and standard deviation ( ⁇ ) of CNTs may be adjusted by changing the CNT manufacturing method and manufacturing conditions, or by combining multiple types of CNTs obtained by different manufacturing methods. May be.
  • the diameter of 100 carbon nanotubes is measured using a transmission electron microscope, the measured diameter is plotted on the horizontal axis, and the frequency is plotted on the vertical axis, and approximated by Gaussian. In this case, a normal distribution is usually used.
  • the CNT preferably has a peak of Radial Breathing Mode (RBM) when evaluated using Raman spectroscopy. Note that there is no RBM in the Raman spectrum of multi-walled carbon nanotubes of three or more layers.
  • RBM Radial Breathing Mode
  • CNTs preferably have a G-band peak intensity ratio (G / D ratio) of 1 to 20 in the Raman spectrum. This is because if the G / D ratio is 1 or more and 20 or less, the average particle diameter of the gold fine particles can be reduced, and the catalytic activity of the catalyst material can be further improved.
  • G / D ratio G-band peak intensity ratio
  • the average diameter (Av) of the CNTs must be 5 nm or less, preferably 0.5 nm or more, and more preferably 1 nm or more. This is because if the average diameter (Av) of CNT exceeds 5 nm, the average particle diameter of the gold fine particles increases, and the catalytic activity of the catalyst material cannot be ensured. Moreover, if the average diameter (Av) of CNT is 0.5 nm or more, the aggregation of CNTs can be suppressed and the dispersibility of CNTs in a solvent in the production process of the catalyst material can be improved.
  • BET specific surface area of the CNT is preferably at 600 meters 2 / g or more in the unopened state, further preferably 800 m 2 / g or more, is preferably from 2500m 2 / g, 1200m 2 / G or less is more preferable. Furthermore, when the CNTs are mainly opened, the BET specific surface area is preferably 1300 m 2 / g or more. This is because if the BET specific surface area of CNT is 600 m 2 / g or more, the catalytic activity of the catalyst material can be improved satisfactorily.
  • the BET specific surface area of CNT is 2500 m ⁇ 2 > / g or less, aggregation of CNT can be suppressed and the dispersibility of CNT in the solvent in the manufacturing process of a catalyst material can be improved.
  • the “BET specific surface area” refers to a nitrogen adsorption specific surface area measured using the BET method.
  • CNTs are obtained as aggregates (CNT aggregates) oriented in a direction substantially perpendicular to the base material on a base material having a catalyst layer for carbon nanotube growth on the surface according to the super growth method described later.
  • the mass density of the CNTs as the aggregate is preferably 0.002 g / cm 3 or more and 0.2 g / cm 3 or less. If the mass density is 0.2 g / cm 3 or less, the CNTs are weakly bonded, so that the CNTs can be uniformly dispersed. In addition, if the mass density is 0.002 g / cm 3 or more, the integrity of the CNTs can be improved and the variation can be suppressed, so that handling becomes easy.
  • the CNT preferably has a plurality of micropores.
  • the CNT preferably has micropores having a pore diameter smaller than 2 nm, and the abundance thereof is a micropore volume determined by the following method, preferably 0.40 mL / g or more, more preferably 0.43 mL. / G or more, more preferably 0.45 mL / g or more, and the upper limit is usually about 0.65 mL / g. Since the CNTs have the above micropores, the aggregation of the CNTs is suppressed, the dispersibility of the CNTs is increased, and the carbon nanofiber dispersion liquid in which the CNTs are highly dispersed is very efficient in the production process of the catalyst material.
  • micropore volume can be adjusted, for example, by appropriately changing the CNT preparation method and preparation conditions.
  • P is a measurement pressure at the time of adsorption equilibrium
  • P0 is a saturated vapor pressure of liquid nitrogen at the time of measurement
  • M is an adsorbate (nitrogen) molecular weight of 28.010
  • ⁇ is an adsorbate (nitrogen).
  • the micropore volume can be determined using, for example, “BELSORP (registered trademark) -mini” (manufactured by Nippon Bell Co., Ltd.).
  • the CNT having the above-described properties is obtained by, for example, supplying a raw material compound and a carrier gas onto a base material having a catalyst layer for producing carbon nanotubes on the surface, and performing chemical vapor deposition (CVD).
  • CVD chemical vapor deposition
  • a catalyst is synthesized, a method of dramatically improving the catalytic activity of the catalyst layer by making a small amount of an oxidizing agent (catalyst activating substance) present in the system (super growth method; see International Publication No. 2006/011655) ),
  • the catalyst layer is formed on the surface of the substrate by a wet process, and a raw material gas containing acetylene as a main component (for example, a gas containing 50% by volume or more of acetylene) can be used for efficient production. it can.
  • the carbon nanotube obtained by the super growth method may be referred to as “SGCNT”.
  • the carbon nanofibers used for the catalyst material are preferably those subjected to oxidation treatment, particularly gas phase plasma treatment.
  • Surface-treated carbon nanofibers (surface-treated CNTs, etc.) obtained by performing oxidation treatment such as gas phase plasma treatment have defects and functional groups such as carboxyl groups, carbonyl groups, and hydroxyl groups on the surface. Presumed. It is surmised that the contribution of such defects and functional groups improves the affinity between the surface and the gold fine particles, but the surface-treated carbon nanofibers further improve the catalytic activity of the resulting catalyst material. Can be made.
  • the gas phase plasma treatment when CNT is used as the carbon nanofiber will be described in detail.
  • the vapor phase plasma treatment can be performed by, for example, a known low temperature plasma treatment.
  • the processing apparatus is not particularly limited, and a known internal electrode type or external electrode type is used, but an external electrode type is preferable because there is no contamination of the electrodes.
  • Processing conditions such as processing pressure, power supply frequency and processing output are not particularly limited, and may be appropriately selected.
  • Organic or inorganic gas is used individually or in mixture of 2 or more types suitably.
  • the gas include oxygen, nitrogen, hydrogen, ammonia, methane, ethylene, argon, and carbon tetrafluoride. Among these, oxygen, nitrogen, and argon are preferable, and nitrogen is more preferable from the viewpoint of maintaining the cylindrical structure of CNT while suitably introducing defects and functional groups on the surface of CNT.
  • the vapor phase plasma treatment is preferably performed while rolling the CNTs.
  • CNT is usually used as a dry powder, and therefore, when the treatment is performed in a stationary state, there is a risk that plasma will not spread throughout.
  • “rolling CNT” does not keep the CNT stationary during the treatment, but reverses the container in which the CNT is accommodated during the treatment or stirs the CNT.
  • the simplest method is a method in which the gas phase plasma treatment is once performed, then taken out and stirred, and then subjected to the gas phase plasma treatment again. That is, the gas phase plasma treatment may be performed while rolling CNTs continuously or intermittently.
  • the conditions of the gas phase plasma treatment vary depending on the plasma generating gas used and the discharge form and cannot be generally stated.
  • the amount of electric power is 0.05 to 2.0 W in terms of energy per unit area of the plasma irradiation area. / Cm 2 and the gas pressure is preferably 5 to 150 Pa.
  • the treatment time irradiation time, treatment time for each time in the case of intermittent irradiation
  • the plasma exhibits a white color.
  • the plasma exhibiting white means that the carbon-carbon bond constituting CNT is eroded and the structure is destroyed. Therefore, in the vapor phase plasma treatment of CNT, it is preferable to select conditions under which the plasma does not exhibit white.
  • the surface of the CNT as a raw material is subjected to gas phase plasma treatment.
  • the processing conditions by appropriately selecting the processing conditions, only the surface layer of the CNT as a raw material can be processed mildly, and excessive destruction of the structure due to the vapor phase plasma processing can be suppressed.
  • the G / D ratio of the surface-treated CNT is 0.1 or more, preferably 0.5 or more, more preferably 1 or more, and usually the upper limit is about 5. is there.
  • the gold fine particle is a component that can function as a catalytically active component in the catalyst material, and is disposed on the surface of the carbon nanofiber as the support described above, and constitutes the catalyst component together with the carbon nanofiber.
  • the shape of the gold fine particles is not particularly limited, and examples thereof include plate shapes such as a spherical shape, a cubic shape, a rectangular shape and a hexagonal plate shape, and rod shapes such as a columnar shape and a hexagonal rod shape.
  • the average particle diameter of the gold fine particles is preferably 2 nm or more, more preferably 4 nm or more, and usually 15 nm or less, preferably 10 nm or less, and preferably 9 nm or less. More preferred. When the average particle diameter of the gold fine particles is within the above range, the catalytic activity of the catalyst material can be further improved.
  • the method for preparing the catalyst material of the present invention described above is not particularly limited as long as it is a method capable of supporting gold fine particles on carbon nanofibers having an average diameter of 5 nm or less. And it is preferable to use the manufacturing method of the catalyst material of this invention as a method of preparing the catalyst material of this invention.
  • carbon nanofibers having an average diameter (Av) of 5 nm or less are converted into cavitation effect or solution in the presence of an ionic surfactant and a polymeric surfactant.
  • One of the major features is that it includes a step of dispersing in a solvent (carbon nanofiber dispersion step) by a dispersion treatment that provides a crushing effect.
  • the dispersion treatment is performed in the presence of the ionic surfactant and the polymeric surfactant, the synergistic effect of the surfactants having different properties ensures the stability of the dispersion liquid and the carbon nano-particles.
  • the fibers can be dispersed well.
  • the carbon nanofibers are dispersed by a dispersion treatment that provides a cavitation effect or a crushing effect, the carbon nanofibers can be prevented from being damaged during the dispersion treatment. Therefore, by using the carbon nanofibers obtained through the above-mentioned carbon nanofiber dispersion process for the preparation of the catalyst material, a catalyst material capable of exhibiting excellent catalytic activity with gold fine particles uniformly supported on the carbon nanofibers is obtained. be able to.
  • the catalyst material of the present invention is, for example, the following steps (2) to (4) after the above (1) carbon nanofiber dispersion step: (2) A step of preparing a mixed solution containing the carbon nanofiber dispersion obtained in the carbon nanofiber dispersion step and a gold precursor (mixed solution preparation step), (3) adding a reducing agent to the mixed solution and reducing the gold precursor to deposit gold fine particles on the surface of the carbon nanofibers to obtain a catalyst material dispersion (reduction step); (4) a step of separating the catalyst material from the catalyst material dispersion (catalyst material separation step), It can be prepared by going through.
  • steps (1) to (4) will be described in detail.
  • Carbon nanofiber dispersion process In the carbon nanofiber dispersion step, carbon nanofibers having an average diameter of 5 nm or less are dispersed in a solvent by a dispersion treatment that provides a cavitation effect or a disintegration effect in the presence of an ionic surfactant and a polymeric surfactant. To obtain a carbon nanofiber dispersion.
  • the ionic surfactant and the polymeric surfactant can function as a dispersant for assisting the dispersion of the carbon nanofibers in the carbon nanofiber dispersion. And in the manufacturing method of the catalyst material of this invention, in order to disperse
  • the carbon nanofiber dispersion may contain a known dispersant other than the ionic surfactant and the polymeric surfactant.
  • any of a cationic surfactant and an anionic surfactant can be used.
  • the cationic surfactant include quaternary ammonium salts and quaternary phosphonium salts.
  • the anionic surfactant include sodium dodecyl sulfate, sodium deoxycholate, sodium cholate, sodium dodecylbenzenesulfonate, sodium dodecyldiphenyloxide disulfonate, and the like. Among these, sodium dodecyl sulfate and sodium deoxycholate are preferable from the viewpoint of excellent dispersibility of carbon nanofibers.
  • the polymer surfactant examples include polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polystyrene sulfonic acid, and salts thereof. Among these, hydroxypropylcellulose and polyvinylpyrrolidone are preferable from the viewpoint of excellent dispersibility of the carbon nanofibers. It should be noted that the surfactant corresponding to the polymeric surfactant composed of a polymer is not included in the ionic surfactant described above.
  • the total addition amount of the ionic surfactant and the polymer surfactant may be an amount that is at least the critical micelle concentration or more.
  • the total addition amount of the ionic surfactant and the polymeric surfactant in the carbon nanofiber dispersion is, for example, 1 to 20 times the amount of carbon nanofibers in the carbon nanofiber dispersion. It can be as follows.
  • the ratio of the addition amount of the polymer surfactant to the addition amount of the ionic surfactant is 0.05 or more and 5 or less.
  • the ratio of the addition amount of the polymeric surfactant to the addition amount of the ionic surfactant is within the above range, the effect obtained by using the ionic surfactant and the polymeric surfactant in combination can be obtained. This is because it can be made sufficiently high.
  • the dispersion treatment that provides a cavitation effect is a dispersion method that uses shock waves generated by bursting of vacuum bubbles generated in water when high energy is applied to a liquid. And by using the said dispersion
  • dispersion treatment examples include dispersion treatment using ultrasonic waves, dispersion treatment using a jet mill, and dispersion treatment using high shear stirring. These distributed processes may be performed only one, or may be performed in combination. More specifically, for example, an ultrasonic homogenizer, a jet mill, and a high shear stirrer are suitably used for the dispersion treatment. These devices may be conventionally known devices.
  • the output is preferably 100 W or more and 500 W or less, and the temperature is preferably 15 ° C. or more and 50 ° C. or less.
  • the number of treatments may be appropriately set depending on the amount of carbon nanofibers, and is preferably 2 times or more, more preferably 5 times or more, preferably 100 times or less, and 50 times or less. More preferred.
  • the pressure is preferably 20 MPa to 250 MPa, and the temperature is preferably 15 ° C. to 50 ° C.
  • the coarse dispersion may be treated with a high shear stirring device.
  • the operation time (the time during which the machine is rotating) is preferably 3 minutes to 4 hours
  • the peripheral speed is 5 m / s to 50 m / s
  • the temperature is preferably 15 ° C. to 50 ° C.
  • the dispersion treatment for obtaining the above cavitation effect it is more preferable to perform the dispersion treatment for obtaining the above cavitation effect at a temperature of 50 ° C. or lower. This is because a change in concentration due to the volatilization of the solvent is suppressed.
  • Dispersion treatment that can produce a crushing effect Moreover, in the carbon nanofiber dispersion step, a dispersion treatment capable of obtaining the crushing effect shown below can be applied. Dispersion treatment that provides this crushing effect allows carbon nanofibers to be uniformly dispersed in the solvent, as well as damage to carbon nanofibers caused by shock waves when bubbles disappear, compared to the dispersion treatment that provides the cavitation effect described above. This is more advantageous in this respect.
  • the above-mentioned coarse dispersion is subjected to shearing force to crush and disperse the aggregates of carbon nanofibers in the coarse dispersion, and a back pressure is applied to the obtained dispersion.
  • a back pressure is applied to the dispersion, the back pressure applied to the dispersion may be reduced to atmospheric pressure at a stretch, but it is preferable to reduce the pressure in multiple stages.
  • a dispersion system having a disperser having the following structure may be used.
  • the disperser has a disperser orifice having an inner diameter d1, a dispersion space having an inner diameter d2, and a terminal portion having an inner diameter d3 from the inflow side to the outflow side of the coarse dispersion liquid (where d2>d3> d1)).
  • the inflowing high-pressure (usually 10 to 400 MPa, preferably 50 to 250 MPa) coarse dispersion passes through the disperser orifice, so that the flow rate of the fluid is reduced while the pressure decreases. And flows into the dispersion space. Thereafter, the high-velocity coarse dispersion liquid flowing into the dispersion space flows at high speed in the dispersion space and receives a shearing force at that time. As a result, the flow rate of the coarse dispersion decreases, and the carbon nanofibers in the coarse dispersion are well dispersed. Then, a fluid having a pressure (back pressure) lower than the pressure of the inflowing coarse dispersion liquid flows out from the terminal portion as the dispersion liquid.
  • back pressure back pressure
  • the back pressure of the dispersion can be applied by applying a load to the flow of the dispersion.
  • a multistage step-down device described later can be provided on the downstream side of the disperser to provide a desired dispersion. Back pressure can be applied. By reducing the back pressure of the dispersion in multiple stages using this multistage pressure reducer, it is possible to suppress the generation of bubbles in the dispersion when the dispersion is finally released to atmospheric pressure.
  • the disperser may include a heat exchanger for cooling the dispersion and a coolant supply mechanism. This is because the generation of bubbles in the dispersion can be further suppressed by cooling the dispersion that has been heated to a high temperature by the shearing force applied by the distributor. In addition, it can suppress that a bubble generate
  • the effect of improving dispersibility by suppressing the adhesion of bubbles to the carbon nanofibers is very large in carbon nanofibers having a large BET specific surface area, particularly carbon nanofibers having a BET specific surface area of 600 m 2 / g or more. This is because the larger the specific surface area of the carbon nanofibers and the easier the carbon nanofibers to adhere to the surface, the more easily the dispersibility decreases when bubbles are generated and attached.
  • a distributed system having the above-described configuration for example, there is a distributed system in which a product name “BERYU SYSTEM PRO” (manufactured by Migrain Co., Ltd.) is combined with a multistage step-down device.
  • BERYU SYSTEM PRO manufactured by Migrain Co., Ltd.
  • a carbon nanofiber dispersion and a gold precursor are included by adding a gold precursor to the carbon nanofiber dispersion obtained through the above-described carbon nanofiber dispersion step and mixing by a known mixing method as necessary. Prepare a mixture.
  • the gold precursor a compound capable of generating gold by a reduction reaction is used.
  • a gold precursor that is soluble in the solvent to be used.
  • Such gold precursor H 2 [AuCl 4], (NH 4) 2 [AuCl 4], H [Au (NO 3) 4] ⁇ H 2 O, NaAuCl 2 ⁇ 2H 2 but O, and the like, It is not limited to these. These can be used singly or in combination of two or more. Of these, NaAuCl 2 .2H 2 O is preferable.
  • the addition amount of the gold precursor can be, for example, 50 times or more and 1000 times or less the addition amount of the carbon nanofibers.
  • a reducing agent is added to the liquid mixture containing the carbon nanofiber dispersion and the gold precursor to reduce the gold precursor. Then, by the reduction reaction, gold fine particles are deposited on the surface of the carbon nanofibers to obtain a catalyst material dispersion liquid in which the catalyst material is dispersed in the solvent.
  • the addition method to the liquid mixture of a reducing agent is not specifically limited, The method of adding a reducing agent to a liquid mixture sequentially is preferable. In order to allow the reduction reaction to proceed sufficiently, it is preferable to stir for about 5 to 30 minutes after the addition of the reducing agent.
  • the reducing agent is not particularly limited as long as it can reduce the above-described gold precursor (cation derived from the gold precursor) and deposit gold fine particles on the surface of the carbon nanofiber.
  • the reducing agent include formic acid, formaldehyde, ammonium formate, dimethylamine borane, tertiary butylamine borane, and triethylamine borane. These can be used singly or in combination of two or more. Of these, dimethylamine borane is preferred.
  • the addition amount of a reducing agent can be 0.01 times or more and 1 time or less of the addition amount of a gold precursor, for example.
  • a reduction reaction can be advanced favorable and gold fine particles can be deposited suitably on the surface of carbon nanofiber.
  • a catalyst material can be obtained from the catalyst material dispersion obtained through the reduction step, for example, by filtration or centrifugation, preferably by filtration.
  • the obtained catalyst material may be washed to remove ionic surfactants and polymer surfactants attached to the catalyst material, or dried to remove unnecessary solvents, if necessary. May be.
  • SGCNT-1> CNT (SGCNT-1) was prepared by the super-growth method according to the description in International Publication No. 2006/011655.
  • the catalyst layer iron thin film
  • the obtained SGCNT-1 has a BET specific surface area of 1050 m 2 / g (unopened) and a micropore volume of 0.45 mL / g, and is characteristic of single-walled CNT in measurement with a Raman spectrophotometer.
  • the obtained SGCNT-2 has a BET specific surface area of 860 m 2 / g (unopened) and a micropore volume of 0.41 mL / g, and is characteristic of single-walled CNT in measurement with a Raman spectrophotometer.
  • a spectrum of radial breathing mode (RBM) was observed in the low wavenumber region of ⁇ 300 cm ⁇ 1 .
  • the average diameter (Av) was 4.6 nm and the standard deviation ( ⁇ ) of the diameter was multiplied by 3.
  • the value (3 ⁇ ) was 2.3 nm and the ratio (3 ⁇ / Av) was 0.50.
  • ⁇ Synthesis Example 3 Surface Treatment SGCNT-2>
  • the SGCNT-2 was subjected to gas phase plasma treatment (plasma generating gas: nitrogen, treatment time: 5 minutes) to prepare surface-treated SGCNT-2.
  • the average diameter (Av), the standard deviation of diameter ( ⁇ ), and 3 ⁇ / Av of the surface-treated SGCNT-2 were the same as the values before the surface treatment.
  • the filtrate was adjusted to 80 ° C., and stirred with a stirrer.
  • a Ferring solution (69.2 g / L copper sulfate pentahydrate aqueous solution, 50 mg potassium potassium tartrate at a concentration of 364 g / L, 100 g / L (Prepared by mixing 50 mL of an aqueous solution in which sodium hydroxide was dissolved in each concentration), and stirring was continued for 30 minutes after the addition of the failing solution. Thereafter, cuprous oxide obtained by suction filtration was recovered, and its weight X was measured.
  • reaction rate (%) (1 ⁇ X / Y) ⁇ 100
  • Example 1 An aqueous solution containing 0.01 g of SGCNT-1 as carbon nanofibers, sodium dodecyl sulfate (SDS) as an ionic surfactant, and hydroxypropyl cellulose (HPC) as a polymeric surfactant, each at a concentration of 1 g / L. In addition to 1 L, the mixture was stirred with a stirrer for 30 minutes to obtain a crude dispersion. SGCNT is obtained by subjecting this coarse dispersion to a dispersion process 20 times under the condition of 50 MPa using a jet mill (manufactured by Joko Co., Ltd., product name “JN-20”), which is a dispersion apparatus utilizing the cavitation effect.
  • SGCNT-1 sodium dodecyl sulfate
  • HPC hydroxypropyl cellulose
  • this catalyst material dispersion was subjected to suction filtration, and the catalyst material 1 could be easily separated from the dispersion.
  • the reaction rate (%) of the catalyst material 1 was 27.9%, and it was confirmed that the catalyst material 1 showed high catalytic activity for glucose oxidation.
  • Example 2 SGCNT-2 is used instead of SGCNT-1 as the carbon nanofiber, and the product name “BERYU SYSTEM PRO” (manufactured by Miebu Co., Ltd.) is used instead of the dispersion treatment for obtaining a cavitation effect as the dispersion treatment.
  • a catalyst material 2 was obtained in the same manner as in Example 1 except that a dispersion treatment that can provide a crushing effect was performed using a dispersion system that is a combination of multistage step down devices.
  • TEM transmission electron microscope
  • Example 3 Catalyst material 3 was obtained in the same manner as in Example 2 except that surface-treated SGCNT-2 was used instead of SGCNT-2 as the carbon nanofiber.
  • TEM transmission electron microscope
  • the catalyst material 3 in which gold fine particles (average particle diameter: 6 nm) are supported on a single-walled CNT structure (SWCNT). was observed (see FIG. 2).
  • the reaction rate (%) of the catalyst material 3 was 28.9%, and it was confirmed that the catalyst material 3 showed high catalytic activity for glucose oxidation.
  • Comparative Example 1 instead of SGCNT-1 as the carbon nanofiber, except that multi-walled carbon nanotubes (MWCNT; manufactured by Nanocyl, product name “NC7000”, BET specific surface area: 290 m 2 / g, average diameter: 9.3 nm) were used.
  • Comparative Example Catalyst Material 1 was obtained in the same manner as Example 1. When the catalyst material dispersion containing the comparative catalyst material 1 is observed with a transmission electron microscope (TEM), a comparative catalyst in which gold fine particles (average particle diameter: 18 nm) are supported on a multilayer CNT structure (MWCNT) Material 1 was observed. The reaction rate (%) of the comparative catalyst material 1 was 21.5%, and it was confirmed that the catalytic activity for glucose oxidation was inferior to that of Examples 1 to 3.
  • TEM transmission electron microscope
  • supported the gold fine particle and was excellent in catalyst activity can be provided.
  • supported the gold fine particle and was excellent in catalytic activity can be provided.

Abstract

The purpose of the present invention is to provide: a catalyst material which is loaded with fine gold particles and has excellent catalytic activity; and a method for producing this catalyst material. A catalyst material according to the present invention is characterized by being obtained by loading carbon nanofibers having an average diameter (Av) of 5 nm or less with fine gold particles. A method for producing a catalyst material according to the present invention is characterized by comprising a step wherein carbon nanofibers having an average diameter (Av) of 5 nm or less are dispersed in a solvent by a dispersing process, by which a cavitation effect or crushing effect can be achieved, in the presence of an ionic surfactant and a polymer surfactant.

Description

触媒材料およびその製造方法Catalyst material and method for producing the same
　本発明は、触媒材料およびその製造方法に関し、特には、金微粒子を含有する触媒材料、および当該触媒材料の製造方法に関するものである。 The present invention relates to a catalyst material and a method for producing the same, and more particularly to a catalyst material containing gold fine particles and a method for producing the catalyst material.
　金は、微粒子とすることにより、低温ＣＯ酸化反応、プロピレンの気相一段エポキシ化反応、低温水性ガスシフト反応、酸素と水素からの直接過酸化水素合成反応、炭化水素類の部分酸化反応など、様々な反応において、優れた触媒活性を発現することが知られている。
　ここで、金などの貴金属は高価であるため、触媒としての使用後に回収することが求められる。そのような使用後の回収を容易とすべく、近年、金微粒子を担体に担持してなる触媒材料が検討されており、併せて、当該触媒材料に優れた触媒活性を発揮させる技術が広く検討されている（例えば、特許文献１、２参照）。 Gold can be made into fine particles, such as low-temperature CO oxidation reaction, propylene vapor phase one-step epoxidation reaction, low-temperature water gas shift reaction, direct hydrogen peroxide synthesis reaction from oxygen and hydrogen, and partial oxidation reaction of hydrocarbons. In such reactions, it is known to exhibit excellent catalytic activity.
Here, since noble metals such as gold are expensive, they are required to be recovered after use as a catalyst. In order to facilitate such post-use recovery, in recent years, catalytic materials in which gold fine particles are supported on a carrier have been studied, and in addition, technologies for exerting excellent catalytic activity on the catalytic materials have been widely studied. (For example, see Patent Documents 1 and 2).
　特許文献１には、金微粒子などの金属粒子が炭素を含有する担体に担持されてなり、当該金属粒子の少なくとも一部が面状領域（例えば最大幅が３~１００ｎｍ）を有する触媒材料が、優れた表面活性を示し、例えば、硝酸性窒素処理用の触媒として優れた効果を奏するとの報告がされている。
　特許文献２には、担体上に金微粒子を分散・固定化して触媒材料を得る方法として、金化合物溶液にカルコゲン化物を添加して形成された金−カルコゲン系イオンを担体と接触させて担体に金−カルコゲン系イオンを吸着させること等により担体表面に金カルコゲナイドを沈殿析出させ、その後担体を分離し加熱することにより担体表面に金微粒子を析出させる方法が開示されている。そして、この方法は特に従来の方法では困難であった酸性担体上への金微粒子の担持を可能とし、そして当該方法により得られる触媒材料は優れた触媒活性を有するとの報告がされている。 Patent Document 1 discloses a catalyst material in which metal particles such as gold fine particles are supported on a carrier containing carbon, and at least a part of the metal particles has a planar region (for example, a maximum width of 3 to 100 nm), It has been reported that it exhibits excellent surface activity and, for example, exhibits excellent effects as a catalyst for treating nitrate nitrogen.
In Patent Document 2, as a method for obtaining a catalyst material by dispersing and immobilizing gold fine particles on a support, gold-chalcogen ions formed by adding a chalcogenide to a gold compound solution are brought into contact with the support to form a support. A method is disclosed in which gold chalcogenide is precipitated on the surface of the carrier by adsorbing gold-chalcogen ions, and then gold fine particles are precipitated on the surface of the carrier by separating and heating the carrier. In addition, it has been reported that this method makes it possible to support gold fine particles on an acidic carrier, which has been difficult with the conventional method, and that the catalyst material obtained by this method has excellent catalytic activity.
特開２０１０−８９０３２号公報JP 2010-89032 A 特開２００９−２４０９５１号公報JP 2009-240951 A
　しかしながら、上記特許文献１および２の技術では、触媒材料に十分満足のいく触媒活性を発揮させることができなかった。例えば特許文献１の技術においては、金微粒子に面状領域を確保するため、金微粒子の粒径をある程度大きくする必要があり、故に金微粒子の比表面積が減少して得られる触媒材料の触媒活性が低下する場合があった。
　くわえて、上記特許文献１および２では、金微粒子およびその担持方法が主として着目されており、金微粒子を担持する担体については、その検討が十分にされていない。すなわち、上記従来の技術には、特に、金微粒子を担持する担体を改良することで、触媒材料に優れた触媒活性を発揮させるという点において、改良の余地があった。 However, the techniques disclosed in Patent Documents 1 and 2 fail to exhibit a sufficiently satisfactory catalytic activity for the catalyst material. For example, in the technique of Patent Document 1, it is necessary to increase the particle size of the gold fine particles to some extent in order to secure a planar region in the gold fine particles, and thus the catalytic activity of the catalyst material obtained by reducing the specific surface area of the gold fine particles. May be reduced.
In addition, Patent Documents 1 and 2 mainly focus on the gold fine particles and the supporting method thereof, and the carrier supporting the gold fine particles has not been sufficiently studied. That is, the above-described conventional technology has room for improvement, particularly in that the catalyst material exhibits excellent catalytic activity by improving the carrier supporting the gold fine particles.
　そこで、本発明は、金微粒子が担持された、触媒活性に優れる触媒材料を提供することを目的とする。
　また、本発明は、金微粒子が担持された、触媒活性に優れる触媒材料の製造方法を提供することを目的とする。 Then, an object of this invention is to provide the catalyst material which was carrying | supported the gold fine particle and was excellent in the catalyst activity.
Another object of the present invention is to provide a method for producing a catalyst material carrying gold fine particles and having excellent catalytic activity.
　本発明者らは、上記目的を達成するために鋭意検討を重ねた。そして、本発明者らは、金微粒子が担体に担持された触媒材料において、担体として、所定の平均直径を備える炭素ナノ繊維を用いることで、触媒材料の触媒活性を優れたものとすることができることを見出し、本発明を完成させた。 The inventors of the present invention have made extensive studies to achieve the above object. The inventors of the present invention may further improve the catalytic activity of the catalyst material by using carbon nanofibers having a predetermined average diameter as the support in the catalyst material in which the gold fine particles are supported on the support. The present invention has been completed by finding out what can be done.
　即ち、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の触媒材料は、平均直径（Ａｖ）が５ｎｍ以下の炭素ナノ繊維に金微粒子が担持されてなることを大きな特徴の一つとする。このように、平均直径が５ｎｍ以下の炭素ナノ繊維と、当該炭素ナノ繊維に担持された金微粒子を含有する触媒材料は、優れた触媒活性を有する。
　なお、本発明において、「繊維」とは、アスペクト比が１０以上のものを指す。また、本発明において、「炭素ナノ繊維の平均直径」は、透過型電子顕微鏡を用いて無作為に選択した炭素ナノ繊維１００本の直径（外径）を測定して求めることができる。 That is, the present invention aims to advantageously solve the above-mentioned problems, and the catalyst material of the present invention is such that gold fine particles are supported on carbon nanofibers having an average diameter (Av) of 5 nm or less. Is one of the major features. Thus, a catalyst material containing carbon nanofibers having an average diameter of 5 nm or less and gold fine particles supported on the carbon nanofibers has excellent catalytic activity.
In the present invention, “fiber” refers to those having an aspect ratio of 10 or more. In the present invention, the “average diameter of carbon nanofibers” can be determined by measuring the diameter (outer diameter) of 100 carbon nanofibers selected at random using a transmission electron microscope.
　ここで、本発明の触媒材料において、前記炭素ナノ繊維が、平均直径（Ａｖ）と直径の標準偏差（σ）とが、関係式：０．２０＜（３σ／Ａｖ）＜０．６０を満たすカーボンナノチューブであることが好ましい。３σ／Ａｖが０．２０超０．６０未満のカーボンナノチューブを使用すれば、触媒材料の触媒活性を更に向上させることができるからである。
　なお、本発明において、「カーボンナノチューブの平均直径（Ａｖ）」および「カーボンナノチューブの直径の標準偏差（σ：標本標準偏差）」は、それぞれ、透過型電子顕微鏡を用いて無作為に選択したカーボンナノチューブ１００本の直径（外径）を測定して求めることができる。 Here, in the catalyst material of the present invention, in the carbon nanofiber, the average diameter (Av) and the standard deviation (σ) of the diameter satisfy the relational expression: 0.20 <(3σ / Av) <0.60. A carbon nanotube is preferred. This is because the catalytic activity of the catalyst material can be further improved by using carbon nanotubes having 3σ / Av of more than 0.20 and less than 0.60.
In the present invention, “average diameter (Av) of carbon nanotubes” and “standard deviation of carbon nanotube diameter (σ: sample standard deviation)” are carbons selected at random using a transmission electron microscope, respectively. It can be obtained by measuring the diameter (outer diameter) of 100 nanotubes.
　また、本発明の触媒材料において、前記炭素ナノ繊維は、気相プラズマ処理が施されていることが好ましい。気相プラズマ処理が施された炭素ナノ繊維を担体として用いることで、触媒材料の触媒活性を更に向上させることができるからである。 In the catalyst material of the present invention, the carbon nanofibers are preferably subjected to gas phase plasma treatment. This is because the catalytic activity of the catalyst material can be further improved by using the carbon nanofibers subjected to the gas phase plasma treatment as a carrier.
　そして、本発明の触媒材料において、前記金微粒子の平均粒径が２ｎｍ以上１０ｎｍ以下であることが好ましい。炭素ナノ繊維に担持された金微粒子の平均粒径が２~１０ｎｍであれば、触媒材料の触媒活性を更に向上させることができるからである。
　なお、本発明において、「金微粒子の平均粒径」は、透過型電子顕微鏡を用いて無作為に選択された１００個の、炭素ナノ繊維に担持された金微粒子の画像に基づいてその粒径（個々の粒子の外縁上の２点を結ぶ線分の長さのうち、最大の長さ）を測定し、求めることができる。 In the catalyst material of the present invention, it is preferable that the average particle diameter of the gold fine particles is 2 nm or more and 10 nm or less. This is because if the average particle size of the gold fine particles supported on the carbon nanofibers is 2 to 10 nm, the catalytic activity of the catalyst material can be further improved.
In the present invention, the “average particle diameter of gold fine particles” is the particle diameter based on images of 100 gold fine particles carried on carbon nanofibers selected at random using a transmission electron microscope. (The maximum length among the lengths of line segments connecting two points on the outer edge of each particle) can be measured and determined.
　また、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の触媒材料の製造方法は、上述した何れかの触媒材料の製造方法であって、平均直径（Ａｖ）が５ｎｍ以下の炭素ナノ繊維を、イオン性界面活性剤および高分子系界面活性剤の存在下で、キャビテーション効果または解砕効果が得られる分散処理によって溶媒に分散させる工程（炭素ナノ繊維分散工程）を含むことを大きな特徴の一つとする。上述の炭素ナノ繊維分散工程を経て得られる炭素ナノ繊維を触媒材料の調製に用いることで、金微粒子が炭素ナノ繊維に均一に担持され、優れた触媒活性を発揮可能である上述した何れかの触媒材料を得ることができる。 Moreover, this invention aims at solving the said subject advantageously, The manufacturing method of the catalyst material of this invention is a manufacturing method of any of the catalyst materials mentioned above, Comprising: Average diameter (Av ) Is a process of dispersing carbon nanofibers of 5 nm or less in a solvent in the presence of an ionic surfactant and a high molecular weight surfactant in a solvent by a dispersion treatment that provides a cavitation effect or a crushing effect (carbon nanofiber dispersion step ) Is one of the major features. By using the carbon nanofibers obtained through the above-mentioned carbon nanofiber dispersion process for the preparation of the catalyst material, the gold fine particles are uniformly supported on the carbon nanofibers and can exhibit excellent catalytic activity. A catalyst material can be obtained.
　本発明によれば、金微粒子が担持された、触媒活性に優れる触媒材料を提供することができる。
　また、本発明によれば、金微粒子が担持された、触媒活性に優れる触媒材料の製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the catalyst material which was carrying | supported the gold fine particle and was excellent in catalyst activity can be provided.
Moreover, according to this invention, the manufacturing method of the catalyst material which was carrying | supported the gold fine particle and was excellent in catalytic activity can be provided.
実施例２の触媒材料のＴＥＭ画像である。4 is a TEM image of the catalyst material of Example 2. 実施例３の触媒材料のＴＥＭ画像である。4 is a TEM image of the catalyst material of Example 3.
　以下、本発明の実施形態について詳細に説明する。
　ここで、本発明の触媒材料は、触媒活性に優れ、各種反応の触媒材料（例えば酸化触媒材料）として好適に用いることができる。そして本発明の触媒材料は、例えば、本発明の触媒材料の製造方法を用いて調製することができる。 Hereinafter, embodiments of the present invention will be described in detail.
Here, the catalyst material of the present invention is excellent in catalytic activity and can be suitably used as a catalyst material (for example, an oxidation catalyst material) for various reactions. And the catalyst material of this invention can be prepared using the manufacturing method of the catalyst material of this invention, for example.
（触媒材料）
　本発明の触媒材料は、担体としての平均直径が５ｎｍ以下の炭素ナノ繊維と、当該炭素ナノ繊維の表面に存在する金微粒子とを備える。そして、本発明の触媒材料は、非常に微細な構造をとる金微粒子を、そのままではなく、担体の表面に担持した状態で、化学反応の触媒として使用される。そして、炭素ナノ繊維表面は、金微粒子との親和性に優れ、金微粒子は炭素ナノ繊維表面に強固に担持されているため、化学反応後に、金微粒子が炭素ナノ繊維表面に担持されたままの触媒材料を容易に回収することができる。
　加えて、本発明の触媒材料を用いれば、特に酸化反応などの化学反応の反応性を向上させることができ、すなわち、本発明の触媒材料は触媒活性に優れる。金微粒子を担持する担体として平均直径が特定の値以下の炭素ナノ繊維を使用することで、触媒材料の触媒活性が向上する理由は定かではないが、上述した炭素ナノ繊維表面と金微粒子の良好な親和性に加え、炭素ナノ繊維の平均直径が小さいことで当該炭素ナノ繊維上に形成される金微粒子の平均粒径も小さくなるためであると推察される。 (Catalyst material)
The catalyst material of the present invention includes carbon nanofibers having an average diameter of 5 nm or less as a support and gold fine particles present on the surface of the carbon nanofibers. The catalyst material of the present invention is used as a catalyst for a chemical reaction in a state where gold fine particles having a very fine structure are supported on the surface of a carrier, not as they are. The carbon nanofiber surface is excellent in affinity with the gold fine particles, and the gold fine particles are firmly supported on the carbon nanofiber surface, so that the gold fine particles remain supported on the carbon nanofiber surface after the chemical reaction. The catalyst material can be easily recovered.
In addition, if the catalyst material of the present invention is used, the reactivity of a chemical reaction such as an oxidation reaction can be improved, that is, the catalyst material of the present invention is excellent in catalytic activity. The reason why the catalytic activity of the catalyst material is improved by using carbon nanofibers having an average diameter of a specific value or less as a carrier for supporting gold fine particles is not clear, but the above-mentioned carbon nanofiber surface and gold fine particles are good. In addition to the above-mentioned affinity, it is presumed that the average particle diameter of the gold fine particles formed on the carbon nanofiber is also reduced by the small average diameter of the carbon nanofiber.
＜炭素ナノ繊維＞
　触媒材料中において、金微粒子を担持する担体として用いられる炭素ナノ繊維としては、平均直径が５ｎｍ以下のカーボンナノチューブまたはカーボンナノファイバーなどを用いることができ、平均直径が５ｎｍ以下のカーボンナノチューブを用いることが好ましい。また、触媒材料の触媒活性を更に向上させる観点からは、炭素ナノ繊維は、酸化処理、特に気相プラズマ処理を施された炭素ナノ繊維であることが好ましい。
　すなわち、触媒材料に用いられる炭素ナノ繊維としては、平均直径が５ｎｍ以下の、気相プラズマ処理が施されたカーボンナノチューブが特に好ましい。 <Carbon nanofiber>
In the catalyst material, as the carbon nanofibers used as a carrier for supporting gold fine particles, carbon nanotubes or carbon nanofibers having an average diameter of 5 nm or less can be used, and carbon nanotubes having an average diameter of 5 nm or less should be used. Is preferred. Further, from the viewpoint of further improving the catalytic activity of the catalyst material, the carbon nanofibers are preferably carbon nanofibers that have been subjected to oxidation treatment, in particular, gas phase plasma treatment.
That is, as the carbon nanofiber used for the catalyst material, a carbon nanotube having an average diameter of 5 nm or less and subjected to gas phase plasma treatment is particularly preferable.
［カーボンナノチューブ］
　ここで、触媒材料に用いられるＣＮＴとしては、平均直径が５ｎｍ以下であれば特に限定されることなく、単層カーボンナノチューブおよび／または多層カーボンナノチューブを用いることができるが、ＣＮＴは、単層から５層までのカーボンナノチューブであることが好ましく、単層カーボンナノチューブであることがより好ましい。単層カーボンナノチューブを使用すれば、多層カーボンナノチューブを使用した場合と比較し、金微粒子の平均粒径を小さくでき、触媒材料の触媒活性を良好に向上させることができるからである。 [carbon nanotube]
Here, the CNT used for the catalyst material is not particularly limited as long as the average diameter is 5 nm or less, and single-walled carbon nanotubes and / or multi-walled carbon nanotubes can be used. It is preferably a carbon nanotube of up to 5 layers, and more preferably a single-walled carbon nanotube. This is because if single-walled carbon nanotubes are used, the average particle diameter of the gold fine particles can be made smaller than when multi-walled carbon nanotubes are used, and the catalytic activity of the catalyst material can be improved satisfactorily.
　また、ＣＮＴとしては、平均直径（Ａｖ）に対する、直径の標準偏差（σ）に３を乗じた値（３σ）の比（３σ／Ａｖ）が０．２０超０．６０未満のＣＮＴを用いることが好ましく、３σ／Ａｖが０．２５超のＣＮＴを用いることがより好ましく、３σ／Ａｖが０．５０超のＣＮＴを用いることが更に好ましい。３σ／Ａｖが０．２０超０．６０未満のＣＮＴを使用すれば、金微粒子の平均粒径を小さくでき、触媒材料の触媒活性を更に向上させることができるからである。
　なお、ＣＮＴの平均直径（Ａｖ）および標準偏差（σ）は、ＣＮＴの製造方法や製造条件を変更することにより調整してもよいし、異なる製法で得られたＣＮＴを複数種類組み合わせることにより調整してもよい。 In addition, as the CNT, a CNT having a ratio (3σ / Av) of a value (3σ) obtained by multiplying the standard deviation (σ) of the diameter by 3 with respect to the average diameter (Av) is more than 0.20 and less than 0.60. It is preferable to use CNTs with 3σ / Av exceeding 0.25, and it is even more preferable to use CNTs with 3σ / Av exceeding 0.50. This is because if 3CNT / Av is more than 0.20 and less than 0.60, the average particle size of the gold fine particles can be reduced and the catalytic activity of the catalyst material can be further improved.
The average diameter (Av) and standard deviation (σ) of CNTs may be adjusted by changing the CNT manufacturing method and manufacturing conditions, or by combining multiple types of CNTs obtained by different manufacturing methods. May be.
　そして、本発明において、ＣＮＴとしては、透過型電子顕微鏡を用いて１００本のカーボンナノチューブの直径を測定し、測定した直径を横軸に、その頻度を縦軸に取ってプロットし、ガウシアンで近似した際に、正規分布を取るものが通常使用される。 In the present invention, as the CNT, the diameter of 100 carbon nanotubes is measured using a transmission electron microscope, the measured diameter is plotted on the horizontal axis, and the frequency is plotted on the vertical axis, and approximated by Gaussian. In this case, a normal distribution is usually used.
　更に、ＣＮＴは、ラマン分光法を用いて評価した際に、Ｒａｄｉａｌ　Ｂｒｅａｔｈｉｎｇ　Ｍｏｄｅ（ＲＢＭ）のピークを有することが好ましい。なお、三層以上の多層カーボンナノチューブのラマンスペクトルには、ＲＢＭが存在しない。 Furthermore, the CNT preferably has a peak of Radial Breathing Mode (RBM) when evaluated using Raman spectroscopy. Note that there is no RBM in the Raman spectrum of multi-walled carbon nanotubes of three or more layers.
　また、ＣＮＴは、ラマンスペクトルにおけるＤバンドピーク強度に対するＧバンドピーク強度の比（Ｇ／Ｄ比）が１以上２０以下であることが好ましい。Ｇ／Ｄ比が１以上２０以下であれば、金微粒子の平均粒径を小さくでき、触媒材料の触媒活性を更に向上させることができるからである。 CNTs preferably have a G-band peak intensity ratio (G / D ratio) of 1 to 20 in the Raman spectrum. This is because if the G / D ratio is 1 or more and 20 or less, the average particle diameter of the gold fine particles can be reduced, and the catalytic activity of the catalyst material can be further improved.
　更に、ＣＮＴの平均直径（Ａｖ）は、５ｎｍ以下であることが必要であり、０．５ｎｍ以上であることが好ましく、１ｎｍ以上であることが更に好ましくい。ＣＮＴの平均直径（Ａｖ）が５ｎｍ超であると、金微粒子の平均粒径が大きくなり、触媒材料の触媒活性を確保することができないからである。また、ＣＮＴの平均直径（Ａｖ）が０．５ｎｍ以上であれば、ＣＮＴの凝集を抑制して、触媒材料の製造工程における溶媒中でのＣＮＴの分散性を高めることができるからである。 Furthermore, the average diameter (Av) of the CNTs must be 5 nm or less, preferably 0.5 nm or more, and more preferably 1 nm or more. This is because if the average diameter (Av) of CNT exceeds 5 nm, the average particle diameter of the gold fine particles increases, and the catalytic activity of the catalyst material cannot be ensured. Moreover, if the average diameter (Av) of CNT is 0.5 nm or more, the aggregation of CNTs can be suppressed and the dispersibility of CNTs in a solvent in the production process of the catalyst material can be improved.
　更に、ＣＮＴのＢＥＴ比表面積は、未開口の状態で６００ｍ２／ｇ以上であることが好ましく、８００ｍ２／ｇ以上であることが更に好ましく、２５００ｍ２／ｇ以下であることが好ましく、１２００ｍ２／ｇ以下であることが更に好ましい。更に、ＣＮＴが主として開口したものにあっては、ＢＥＴ比表面積が１３００ｍ２／ｇ以上であることが好ましい。ＣＮＴのＢＥＴ比表面積が６００ｍ２／ｇ以上であれば、触媒材料の触媒活性を良好に向上させることができるからである。また、ＣＮＴのＢＥＴ比表面積が２５００ｍ２／ｇ以下であれば、ＣＮＴの凝集を抑制して、触媒材料の製造工程における溶媒中でのＣＮＴの分散性を高めることができるからである。
　なお、本発明において、「ＢＥＴ比表面積」とは、ＢＥＴ法を用いて測定した窒素吸着比表面積を指す。 Further, BET specific surface area of the CNT is preferably at 600 meters 2 / g or more in the unopened state, further preferably 800 m 2 / g or more, is preferably from 2500m 2 / g, 1200m 2 / G or less is more preferable. Furthermore, when the CNTs are mainly opened, the BET specific surface area is preferably 1300 m 2 / g or more. This is because if the BET specific surface area of CNT is 600 m 2 / g or more, the catalytic activity of the catalyst material can be improved satisfactorily. Moreover, if the BET specific surface area of CNT is 2500 m < 2 > / g or less, aggregation of CNT can be suppressed and the dispersibility of CNT in the solvent in the manufacturing process of a catalyst material can be improved.
In the present invention, the “BET specific surface area” refers to a nitrogen adsorption specific surface area measured using the BET method.
　更に、ＣＮＴは、後述のスーパーグロース法によれば、カーボンナノチューブ成長用の触媒層を表面に有する基材上に、基材に略垂直な方向に配向した集合体（ＣＮＴ配向集合体）として得られるが、当該集合体としての、ＣＮＴの質量密度は、０．００２ｇ／ｃｍ３以上０．２ｇ／ｃｍ３以下であることが好ましい。質量密度が０．２ｇ／ｃｍ３以下であれば、ＣＮＴ同士の結びつきが弱くなるので、ＣＮＴを均質に分散させることができる。また、質量密度が０．００２ｇ／ｃｍ３以上であれば、ＣＮＴの一体性を向上させ、バラけることを抑制できるため取り扱いが容易になる。 Furthermore, CNTs are obtained as aggregates (CNT aggregates) oriented in a direction substantially perpendicular to the base material on a base material having a catalyst layer for carbon nanotube growth on the surface according to the super growth method described later. However, the mass density of the CNTs as the aggregate is preferably 0.002 g / cm 3 or more and 0.2 g / cm 3 or less. If the mass density is 0.2 g / cm 3 or less, the CNTs are weakly bonded, so that the CNTs can be uniformly dispersed. In addition, if the mass density is 0.002 g / cm 3 or more, the integrity of the CNTs can be improved and the variation can be suppressed, so that handling becomes easy.
　更に、ＣＮＴは、複数の微小孔を有することが好ましい。ＣＮＴは、中でも、孔径が２ｎｍよりも小さいマイクロ孔を有するのが好ましく、その存在量は、下記の方法で求めたマイクロ孔容積で、好ましくは０．４０ｍＬ／ｇ以上、より好ましくは０．４３ｍＬ／ｇ以上、更に好ましくは０．４５ｍＬ／ｇ以上であり、上限としては、通常、０．６５ｍＬ／ｇ程度である。ＣＮＴが上記のようなマイクロ孔を有することで、ＣＮＴの凝集が抑制され、ＣＮＴの分散性が高まり、触媒材料の製造工程において、ＣＮＴが高度に分散した炭素ナノ繊維分散液を非常に効率的に得ることができる。なお、マイクロ孔容積は、例えば、ＣＮＴの調製方法および調製条件を適宜変更することで調整することができる。
　ここで、「マイクロ孔容積（Ｖｐ）」は、ＣＮＴの液体窒素温度（７７Ｋ）での窒素吸脱着等温線を測定し、相対圧Ｐ／Ｐ０＝０．１９における窒素吸着量をＶとして、式（Ｉ）：Ｖｐ＝（Ｖ／２２４１４）×（Ｍ／ρ）より、算出することができる。なお、Ｐは吸着平衡時の測定圧力、Ｐ０は測定時の液体窒素の飽和蒸気圧であり、式（Ｉ）中、Ｍは吸着質（窒素）の分子量２８．０１０、ρは吸着質（窒素）の７７Ｋにおける密度０．８０８ｇ／ｃｍ３である。マイクロ孔容積は、例えば、「ＢＥＬＳＯＲＰ（登録商標）−ｍｉｎｉ」（日本ベル（株）製）を使用して求めることができる。 Furthermore, the CNT preferably has a plurality of micropores. Among them, the CNT preferably has micropores having a pore diameter smaller than 2 nm, and the abundance thereof is a micropore volume determined by the following method, preferably 0.40 mL / g or more, more preferably 0.43 mL. / G or more, more preferably 0.45 mL / g or more, and the upper limit is usually about 0.65 mL / g. Since the CNTs have the above micropores, the aggregation of the CNTs is suppressed, the dispersibility of the CNTs is increased, and the carbon nanofiber dispersion liquid in which the CNTs are highly dispersed is very efficient in the production process of the catalyst material. Can get to. The micropore volume can be adjusted, for example, by appropriately changing the CNT preparation method and preparation conditions.
Here, the “micropore volume (Vp)” is an equation in which the nitrogen adsorption / desorption isotherm at the liquid nitrogen temperature (77 K) of CNT is measured and the nitrogen adsorption amount at relative pressure P / P0 = 0.19 is V. (I): Vp = (V / 22414) × (M / ρ). Here, P is a measurement pressure at the time of adsorption equilibrium, P0 is a saturated vapor pressure of liquid nitrogen at the time of measurement, and in formula (I), M is an adsorbate (nitrogen) molecular weight of 28.010, and ρ is an adsorbate (nitrogen). ) At 77K with a density of 0.808 g / cm 3 . The micropore volume can be determined using, for example, “BELSORP (registered trademark) -mini” (manufactured by Nippon Bell Co., Ltd.).
　なお、上述した性状を有するＣＮＴは、例えば、カーボンナノチューブ製造用の触媒層を表面に有する基材上に、原料化合物およびキャリアガスを供給して、化学的気相成長法（ＣＶＤ法）によりＣＮＴを合成する際に、系内に微量の酸化剤（触媒賦活物質）を存在させることで、触媒層の触媒活性を飛躍的に向上させるという方法（スーパーグロース法；国際公開第２００６／０１１６５５号参照）において、基材表面への触媒層の形成をウェットプロセスにより行い、アセチレンを主成分とする原料ガス（例えば、アセチレンを５０体積％以上含むガス）を用いることにより、効率的に製造することができる。なお、以下では、スーパーグロース法により得られるカーボンナノチューブを「ＳＧＣＮＴ」と称することがある。 The CNT having the above-described properties is obtained by, for example, supplying a raw material compound and a carrier gas onto a base material having a catalyst layer for producing carbon nanotubes on the surface, and performing chemical vapor deposition (CVD). When a catalyst is synthesized, a method of dramatically improving the catalytic activity of the catalyst layer by making a small amount of an oxidizing agent (catalyst activating substance) present in the system (super growth method; see International Publication No. 2006/011655) ), The catalyst layer is formed on the surface of the substrate by a wet process, and a raw material gas containing acetylene as a main component (for example, a gas containing 50% by volume or more of acetylene) can be used for efficient production. it can. Hereinafter, the carbon nanotube obtained by the super growth method may be referred to as “SGCNT”.
［気相プラズマ処理］
　触媒材料に用いられる炭素ナノ繊維は、酸化処理、特に気相プラズマ処理を施したものであることが好ましい。気相プラズマ処理などの酸化処理を施すことで得られる表面処理炭素ナノ繊維（表面処理ＣＮＴなど）は、その表面に欠陥、並びにカルボキシル基、カルボニル基及びヒドロキシル基などの官能基が生じていると推定される。そのような欠陥および官能基の寄与により当該表面と金微粒子との親和性が向上するためであると推察されるが、表面処理炭素ナノ繊維を用いれば、得られる触媒材料の触媒活性を更に向上させることができる。以下、炭素ナノ繊維としてＣＮＴを使用した場合の、気相プラズマ処理について詳述する。 [Gas phase plasma treatment]
The carbon nanofibers used for the catalyst material are preferably those subjected to oxidation treatment, particularly gas phase plasma treatment. Surface-treated carbon nanofibers (surface-treated CNTs, etc.) obtained by performing oxidation treatment such as gas phase plasma treatment have defects and functional groups such as carboxyl groups, carbonyl groups, and hydroxyl groups on the surface. Presumed. It is surmised that the contribution of such defects and functional groups improves the affinity between the surface and the gold fine particles, but the surface-treated carbon nanofibers further improve the catalytic activity of the resulting catalyst material. Can be made. Hereinafter, the gas phase plasma treatment when CNT is used as the carbon nanofiber will be described in detail.
　気相プラズマ処理は、例えば、公知の低温プラズマ処理により行うことができる。処理装置としては、特に限定されるものではなく、公知の内部電極方式又は外部電極方式のものが使用されるが、電極の汚染がない点から外部電極方式のものが好ましい。処理圧力、電源周波数及び処理出力などの処理条件は特に限定されるものではなく、適宜選定すればよい。プラズマ発生ガスとしては、特に限定されないが、有機又は無機ガスが適宜、単独で又は２種以上を混合して用いられる。当該ガスとしては、例えば、酸素、窒素、水素、アンモニア、メタン、エチレン、アルゴン、及び四フッ化炭素などが挙げられる。中でも、ＣＮＴの表面に欠陥および官能基を好適に導入しつつ、ＣＮＴの円筒構造を保持する観点からは、酸素、窒素、アルゴンが好ましく、窒素がより好ましい。 The vapor phase plasma treatment can be performed by, for example, a known low temperature plasma treatment. The processing apparatus is not particularly limited, and a known internal electrode type or external electrode type is used, but an external electrode type is preferable because there is no contamination of the electrodes. Processing conditions such as processing pressure, power supply frequency and processing output are not particularly limited, and may be appropriately selected. Although it does not specifically limit as plasma generation gas, Organic or inorganic gas is used individually or in mixture of 2 or more types suitably. Examples of the gas include oxygen, nitrogen, hydrogen, ammonia, methane, ethylene, argon, and carbon tetrafluoride. Among these, oxygen, nitrogen, and argon are preferable, and nitrogen is more preferable from the viewpoint of maintaining the cylindrical structure of CNT while suitably introducing defects and functional groups on the surface of CNT.
　気相プラズマ処理は、ＣＮＴを転動させながら行うことが好ましい。ＣＮＴは、通常、乾燥粉体として用いられるため、静置した状態で当該処理を行うと、全体にプラズマが行き渡らない虞があるからである。ここで本発明において「ＣＮＴを転動させる」とは、処理の際にＣＮＴを静置させ続けるのではなく、当該処理の際にＣＮＴが収容されている容器を反転することや、ＣＮＴを攪拌することをいう。最も簡単には、一旦気相プラズマ処理を施した後、一度取り出して攪拌し、再度気相プラズマ処理を施す方法が挙げられる。すなわち、気相プラズマ処理は、連続的または間欠的にＣＮＴを転動させながらおこなってもよい。 The vapor phase plasma treatment is preferably performed while rolling the CNTs. This is because CNT is usually used as a dry powder, and therefore, when the treatment is performed in a stationary state, there is a risk that plasma will not spread throughout. Here, in the present invention, “rolling CNT” does not keep the CNT stationary during the treatment, but reverses the container in which the CNT is accommodated during the treatment or stirs the CNT. To do. The simplest method is a method in which the gas phase plasma treatment is once performed, then taken out and stirred, and then subjected to the gas phase plasma treatment again. That is, the gas phase plasma treatment may be performed while rolling CNTs continuously or intermittently.
　気相プラズマ処理の条件は、用いるプラズマ発生ガスや放電形態などにより異なり、一概には言えないが、例えば、電力量としてはプラズマ照射面積の単位面積当たりのエネルギーで、０．０５~２．０Ｗ／ｃｍ２、ガス圧は５~１５０Ｐａが好ましい。
　処理時間（照射時間、間欠的に照射する場合は各回の処理時間）は適宜設定すればよいが、通常、０．１~１２０分、好ましくは１~３０分、より好ましくは２~２０分である。処理時間を上述の範囲内とすることで、ＣＮＴの表面に欠陥および官能基を好適に導入しつつ、ＣＮＴの円筒構造を十分に保持することができる。
　なお、プラズマ発生ガスとして二酸化炭素を使用した場合、プラズマが白色を呈することが一般に知られている。ここで、ＣＮＴの気相プラズマ処理においてプラズマが白色を呈するということは、ＣＮＴを構成する炭素−炭素の結合が侵され、構造が破壊されていることを意味する。従って、ＣＮＴの気相プラズマ処理では、プラズマが白色を呈さない条件を選択することが好ましい。 The conditions of the gas phase plasma treatment vary depending on the plasma generating gas used and the discharge form and cannot be generally stated. For example, the amount of electric power is 0.05 to 2.0 W in terms of energy per unit area of the plasma irradiation area. / Cm 2 and the gas pressure is preferably 5 to 150 Pa.
The treatment time (irradiation time, treatment time for each time in the case of intermittent irradiation) may be set as appropriate, but is usually 0.1 to 120 minutes, preferably 1 to 30 minutes, more preferably 2 to 20 minutes. is there. By setting the treatment time within the above-described range, it is possible to sufficiently hold the cylindrical structure of the CNT while suitably introducing defects and functional groups on the surface of the CNT.
Note that it is generally known that when carbon dioxide is used as the plasma generating gas, the plasma exhibits a white color. Here, in the vapor phase plasma treatment of CNT, the plasma exhibiting white means that the carbon-carbon bond constituting CNT is eroded and the structure is destroyed. Therefore, in the vapor phase plasma treatment of CNT, it is preferable to select conditions under which the plasma does not exhibit white.
　以上により、原料としてのＣＮＴの表面が気相プラズマ処理される。なお、処理条件を適宜選択することで、原料としてのＣＮＴの表面層のみをマイルドに処理可能であり、気相プラズマ処理による構造の過度な破壊を抑制することができる。本発明の所望の効果を発現させる観点から、表面処理ＣＮＴのＧ／Ｄ比は０．１以上であり、好ましくは０．５以上、より好ましくは１以上であり、通常、上限は５程度である。 Thus, the surface of the CNT as a raw material is subjected to gas phase plasma treatment. Note that by appropriately selecting the processing conditions, only the surface layer of the CNT as a raw material can be processed mildly, and excessive destruction of the structure due to the vapor phase plasma processing can be suppressed. From the viewpoint of expressing the desired effect of the present invention, the G / D ratio of the surface-treated CNT is 0.1 or more, preferably 0.5 or more, more preferably 1 or more, and usually the upper limit is about 5. is there.
＜金微粒子＞
　金微粒子は、触媒材料中において、触媒活性成分として機能しうる成分であり、上述した担体としての炭素ナノ繊維の表面に配置され、炭素ナノ繊維と一体となって触媒成分を構成する。金微粒子の形状としては、特に限定されるものではなく、例えば、球状、立方体状、長方形状および六角板状などの板状、柱状、六角棒状などの棒状が挙げられる。 <Gold fine particles>
The gold fine particle is a component that can function as a catalytically active component in the catalyst material, and is disposed on the surface of the carbon nanofiber as the support described above, and constitutes the catalyst component together with the carbon nanofiber. The shape of the gold fine particles is not particularly limited, and examples thereof include plate shapes such as a spherical shape, a cubic shape, a rectangular shape and a hexagonal plate shape, and rod shapes such as a columnar shape and a hexagonal rod shape.
　ここで、金微粒子の平均粒径は、２ｎｍ以上であることが好ましく、４ｎｍ以上であることがより好ましく、また、通常１５ｎｍ以下であり、１０ｎｍ以下であることが好ましく、９ｎｍ以下であることがより好ましい。金微粒子の平均粒径が上述の範囲内であることで、触媒材料の触媒活性を更に優れたものとすることができる。 Here, the average particle diameter of the gold fine particles is preferably 2 nm or more, more preferably 4 nm or more, and usually 15 nm or less, preferably 10 nm or less, and preferably 9 nm or less. More preferred. When the average particle diameter of the gold fine particles is within the above range, the catalytic activity of the catalyst material can be further improved.
（触媒材料の製造方法）
　上述した本発明の触媒材料を調製する方法としては、平均直径が５ｎｍ以下の炭素ナノ繊維上に金微粒子を担持させることが可能な方法であれば特に限定されない。そして、本発明の触媒材料を調製する方法としては、本発明の触媒材料の製造方法を用いることが好ましい。 (Method for producing catalyst material)
The method for preparing the catalyst material of the present invention described above is not particularly limited as long as it is a method capable of supporting gold fine particles on carbon nanofibers having an average diameter of 5 nm or less. And it is preferable to use the manufacturing method of the catalyst material of this invention as a method of preparing the catalyst material of this invention.
　具体的には、本発明の触媒材料の製造方法は、平均直径（Ａｖ）が５ｎｍ以下の炭素ナノ繊維を、イオン性界面活性剤および高分子系界面活性剤の存在下で、キャビテーション効果または解砕効果が得られる分散処理によって溶媒に分散させる工程（炭素ナノ繊維分散工程）を含むことを大きな特徴の一つとする。このように、イオン性界面活性剤および高分子系界面活性剤の存在下で分散処理を実施すれば、性状の異なる界面活性剤の相乗効果により、分散液の安定性を確保しつつ、炭素ナノ繊維を良好に分散させることができる。また、キャビテーション効果または解砕効果が得られる分散処理によって炭素ナノ繊維を分散させれば、分散処理中に炭素ナノ繊維が損傷するのを抑制することができる。したがって、上述の炭素ナノ繊維分散工程を経て得られる炭素ナノ繊維を触媒材料の調製に用いることで、金微粒子が炭素ナノ繊維に均一に担持され、優れた触媒活性を発揮可能な触媒材料を得ることができる。 Specifically, in the method for producing a catalyst material of the present invention, carbon nanofibers having an average diameter (Av) of 5 nm or less are converted into cavitation effect or solution in the presence of an ionic surfactant and a polymeric surfactant. One of the major features is that it includes a step of dispersing in a solvent (carbon nanofiber dispersion step) by a dispersion treatment that provides a crushing effect. As described above, when the dispersion treatment is performed in the presence of the ionic surfactant and the polymeric surfactant, the synergistic effect of the surfactants having different properties ensures the stability of the dispersion liquid and the carbon nano-particles. The fibers can be dispersed well. In addition, if the carbon nanofibers are dispersed by a dispersion treatment that provides a cavitation effect or a crushing effect, the carbon nanofibers can be prevented from being damaged during the dispersion treatment. Therefore, by using the carbon nanofibers obtained through the above-mentioned carbon nanofiber dispersion process for the preparation of the catalyst material, a catalyst material capable of exhibiting excellent catalytic activity with gold fine particles uniformly supported on the carbon nanofibers is obtained. be able to.
　そして、本発明の触媒材料は、上述の（１）炭素ナノ繊維分散工程後に、例えば更に以下の工程（２）~（４）：
（２）前記炭素ナノ繊維分散液工程で得られた炭素ナノ繊維分散液および金前躯体を含む混合液を調製する工程（混合液調製工程）、
（３）前記混合液に還元剤を添加し、前記金前躯体を還元することで前記炭素ナノ繊維の表面に金微粒子を析出させ、触媒材料分散液を得る工程（還元工程）、
（４）前記触媒材料分散液から触媒材料を分離する工程（触媒材料分離工程）、
　を経ることで、調製することができる。以下、上述した（１）~（４）の工程について詳述する。 Then, the catalyst material of the present invention is, for example, the following steps (2) to (4) after the above (1) carbon nanofiber dispersion step:
(2) A step of preparing a mixed solution containing the carbon nanofiber dispersion obtained in the carbon nanofiber dispersion step and a gold precursor (mixed solution preparation step),
(3) adding a reducing agent to the mixed solution and reducing the gold precursor to deposit gold fine particles on the surface of the carbon nanofibers to obtain a catalyst material dispersion (reduction step);
(4) a step of separating the catalyst material from the catalyst material dispersion (catalyst material separation step),
It can be prepared by going through. Hereinafter, the above-described steps (1) to (4) will be described in detail.
＜炭素ナノ繊維分散工程＞
　炭素ナノ繊維分散工程では、平均直径が５ｎｍ以下の炭素ナノ繊維を、イオン性界面活性剤および高分子系界面活性剤の存在下で、キャビテーション効果または解砕効果が得られる分散処理によって溶媒に分散させ、炭素ナノ繊維分散液を得る。 <Carbon nanofiber dispersion process>
In the carbon nanofiber dispersion step, carbon nanofibers having an average diameter of 5 nm or less are dispersed in a solvent by a dispersion treatment that provides a cavitation effect or a disintegration effect in the presence of an ionic surfactant and a polymeric surfactant. To obtain a carbon nanofiber dispersion.
［イオン性界面活性剤および高分子系界面活性剤］
　イオン性界面活性剤および高分子系界面活性剤は、炭素ナノ繊維分散液中で炭素ナノ繊維の分散を補助する分散剤として機能し得るものである。そして、本発明の触媒材料の製造方法では、炭素ナノ繊維を良好に分散させるために、イオン性界面活性剤と高分子系界面活性剤とを併用する。なお、炭素ナノ繊維分散液は、イオン性界面活性剤および高分子系界面活性剤以外の既知の分散剤を含有していてもよい。 [Ionic surfactants and polymeric surfactants]
The ionic surfactant and the polymeric surfactant can function as a dispersant for assisting the dispersion of the carbon nanofibers in the carbon nanofiber dispersion. And in the manufacturing method of the catalyst material of this invention, in order to disperse | distribute carbon nanofiber favorably, an ionic surfactant and polymeric surfactant are used together. The carbon nanofiber dispersion may contain a known dispersant other than the ionic surfactant and the polymeric surfactant.
−イオン性界面活性剤−
　ここで、イオン性界面活性剤としては、カチオン性界面活性剤およびアニオン性界面活性剤の何れも用いることができる。
　そして、カチオン性界面活性剤としては、例えば、４級アンモニウム塩、４級ホスホニウム塩などが挙げられる。
　また、アニオン性界面活性剤としては、例えば、ドデシル硫酸ナトリウム、デオキシコール酸ナトリウム、コール酸ナトリウム、ドデシルベンゼンスルホン酸ナトリウム、ドデシルジフェニルオキシドジスルホン酸ナトリウムなどが挙げられる。これらの中でも、炭素ナノ繊維の分散性に優れる観点からは、ドデシル硫酸ナトリウム、デオキシコール酸ナトリウムが好ましい。 -Ionic surfactant-
Here, as the ionic surfactant, any of a cationic surfactant and an anionic surfactant can be used.
Examples of the cationic surfactant include quaternary ammonium salts and quaternary phosphonium salts.
Examples of the anionic surfactant include sodium dodecyl sulfate, sodium deoxycholate, sodium cholate, sodium dodecylbenzenesulfonate, sodium dodecyldiphenyloxide disulfonate, and the like. Among these, sodium dodecyl sulfate and sodium deoxycholate are preferable from the viewpoint of excellent dispersibility of carbon nanofibers.
−高分子系界面活性剤−
　高分子系界面活性剤としては、ポリビニルピロリドン、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、ポリビニルアルコール、ポリスチレンスルホン酸、および、それらの塩などが挙げられる。これらの中でも、炭素ナノ繊維の分散性に優れる観点からは、ヒドロキシプロピルセルロース、ポリビニルピロリドンが好ましい。なお、高分子で構成される高分子系界面活性剤に該当する界面活性剤は、上述したイオン性界面活性剤には含まれないものとする。 -High molecular weight surfactant-
Examples of the polymer surfactant include polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polystyrene sulfonic acid, and salts thereof. Among these, hydroxypropylcellulose and polyvinylpyrrolidone are preferable from the viewpoint of excellent dispersibility of the carbon nanofibers. It should be noted that the surfactant corresponding to the polymeric surfactant composed of a polymer is not included in the ionic surfactant described above.
−添加量−
　なお、イオン性界面活性剤および高分子系界面活性剤の合計添加量は、少なくとも臨界ミセル濃度以上となる量であればよい。具体的には、炭素ナノ繊維分散液中のイオン性界面活性剤および高分子系界面活性剤の合計添加量は、例えば、炭素ナノ繊維分散液中の炭素ナノ繊維の量の１倍以上２０倍以下とすることができる。
　そして、イオン性界面活性剤の添加量に対する高分子系界面活性剤の添加量の比（高分子系界面活性剤の添加量／イオン性界面活性剤の添加量）は、０．０５以上５以下とすることが好ましい。イオン性界面活性剤の添加量に対する高分子系界面活性剤の添加量の比を上記範囲内とすれば、イオン性界面活性剤と高分子系界面活性剤とを併用することにより得られる効果を十分に高くすることができるからである。 -Addition amount-
In addition, the total addition amount of the ionic surfactant and the polymer surfactant may be an amount that is at least the critical micelle concentration or more. Specifically, the total addition amount of the ionic surfactant and the polymeric surfactant in the carbon nanofiber dispersion is, for example, 1 to 20 times the amount of carbon nanofibers in the carbon nanofiber dispersion. It can be as follows.
The ratio of the addition amount of the polymer surfactant to the addition amount of the ionic surfactant (addition amount of the polymer surfactant / addition amount of the ionic surfactant) is 0.05 or more and 5 or less. It is preferable that If the ratio of the addition amount of the polymeric surfactant to the addition amount of the ionic surfactant is within the above range, the effect obtained by using the ionic surfactant and the polymeric surfactant in combination can be obtained. This is because it can be made sufficiently high.
［キャビテーション効果が得られる分散処理］
　次に、炭素ナノ繊維分散工程に使用しうる、キャビテーション効果が得られる分散処理について説明する。キャビテーション効果が得られる分散処理は、液体に高エネルギーを付与した際に、水に生じた真空の気泡が破裂することにより生じた衝撃波を利用した分散方法である。そして、当該分散処理方法を用いることにより、炭素ナノ繊維を溶媒中に均一に分散させることができ、ひいては、得られる触媒材料の触媒活性を向上させることが可能となる。 [Distributed processing with cavitation effect]
Next, a dispersion treatment that can be used in the carbon nanofiber dispersion step and that provides a cavitation effect will be described. The dispersion treatment that provides a cavitation effect is a dispersion method that uses shock waves generated by bursting of vacuum bubbles generated in water when high energy is applied to a liquid. And by using the said dispersion | distribution processing method, carbon nanofiber can be disperse | distributed uniformly in a solvent, and it becomes possible to improve the catalyst activity of the catalyst material obtained by extension.
　ここで、キャビテーション効果が得られる分散処理の具体例としては、超音波による分散処理、ジェットミルによる分散処理および高せん断撹拌による分散処理が挙げられる。これらの分散処理は一つのみを行なってもよく、複数を組み合わせて行なってもよい。より具体的には、分散処理には、例えば超音波ホモジナイザー、ジェットミル、および高せん断撹拌装置が好適に用いられる。これらの装置は従来公知のものを使用すればよい。 Here, specific examples of the dispersion treatment that can obtain the cavitation effect include dispersion treatment using ultrasonic waves, dispersion treatment using a jet mill, and dispersion treatment using high shear stirring. These distributed processes may be performed only one, or may be performed in combination. More specifically, for example, an ultrasonic homogenizer, a jet mill, and a high shear stirrer are suitably used for the dispersion treatment. These devices may be conventionally known devices.
　炭素ナノ繊維の分散に超音波ホモジナイザーを用いる場合には、イオン性界面活性剤および高分子系界面活性剤を添加した溶媒に炭素ナノ繊維を加えた後、得られた粗分散液に対して超音波ホモジナイザーにより超音波を照射すればよい。照射する時間は、炭素ナノ繊維の量などにより適宜設定すればよく、例えば、３分以上が好ましく、３０分以上がより好ましく、また、５時間以下が好ましく、２時間以下がより好ましい。また、例えば、出力は１００Ｗ以上５００Ｗ以下、温度は１５℃以上５０℃以下が好ましい。 When using an ultrasonic homogenizer to disperse carbon nanofibers, after adding carbon nanofibers to a solvent containing an ionic surfactant and a polymeric surfactant, What is necessary is just to irradiate an ultrasonic wave with a sound wave homogenizer. What is necessary is just to set suitably for the time to irradiate according to the quantity of carbon nanofiber etc. For example, 3 minutes or more are preferable, 30 minutes or more are more preferable, 5 hours or less are preferable, and 2 hours or less are more preferable. For example, the output is preferably 100 W or more and 500 W or less, and the temperature is preferably 15 ° C. or more and 50 ° C. or less.
　また、ジェットミルを用いる場合、処理回数は、炭素ナノ繊維の量などにより適宜設定すればよく、例えば、２回以上が好ましく、５回以上がより好ましく、１００回以下が好ましく、５０回以下がより好ましい。また、例えば、圧力は２０ＭＰａ~２５０ＭＰａ、温度は１５℃~５０℃が好ましい。 In the case of using a jet mill, the number of treatments may be appropriately set depending on the amount of carbon nanofibers, and is preferably 2 times or more, more preferably 5 times or more, preferably 100 times or less, and 50 times or less. More preferred. For example, the pressure is preferably 20 MPa to 250 MPa, and the temperature is preferably 15 ° C. to 50 ° C.
　さらに、高せん断撹拌を用いる場合には、高せん断撹拌装置により粗分散液を処理すればよい。旋回速度は速ければ速いほどよい。例えば、運転時間（機械が回転動作をしている時間）は３分以上４時間以下、周速は５ｍ／ｓ以上５０ｍ／ｓ以下、温度は１５℃以上５０℃以下が好ましい。 Furthermore, when using high shear stirring, the coarse dispersion may be treated with a high shear stirring device. The faster the turning speed, the better. For example, the operation time (the time during which the machine is rotating) is preferably 3 minutes to 4 hours, the peripheral speed is 5 m / s to 50 m / s, and the temperature is preferably 15 ° C. to 50 ° C.
　なお、上記したキャビテーション効果が得られる分散処理は、５０℃以下の温度で行なうことがより好ましい。溶媒の揮発による濃度変化が抑制されるからである。 In addition, it is more preferable to perform the dispersion treatment for obtaining the above cavitation effect at a temperature of 50 ° C. or lower. This is because a change in concentration due to the volatilization of the solvent is suppressed.
［解砕効果が得られる分散処理］
　また、炭素ナノ繊維分散工程では、以下に示す解砕効果が得られる分散処理を適用することもできる。この解砕効果が得られる分散処理は、炭素ナノ繊維を溶媒中に均一に分散できることは勿論、上記したキャビテーション効果が得られる分散処理に比べ、気泡が消滅する際の衝撃波による炭素ナノ繊維の損傷を抑制することができるので、この点で一層有利である。 [Dispersion treatment that can produce a crushing effect]
Moreover, in the carbon nanofiber dispersion step, a dispersion treatment capable of obtaining the crushing effect shown below can be applied. Dispersion treatment that provides this crushing effect allows carbon nanofibers to be uniformly dispersed in the solvent, as well as damage to carbon nanofibers caused by shock waves when bubbles disappear, compared to the dispersion treatment that provides the cavitation effect described above. This is more advantageous in this respect.
　この解砕効果が得られる分散処理では、上記した粗分散液にせん断力を与えて粗分散液中の炭素ナノ繊維の凝集体を解砕・分散させ、さらに得られた分散液に背圧を負荷し、また所望により、分散液を冷却することで、キャビテーションの発生を抑制しつつ、炭素ナノ繊維を溶媒中に均一に分散させることができる。
　なお、分散液に背圧を負荷する場合、分散液に負荷した背圧は、大気圧まで一気に降圧させてもよいが、多段階で降圧することが好ましい。 In the dispersion treatment in which this crushing effect is obtained, the above-mentioned coarse dispersion is subjected to shearing force to crush and disperse the aggregates of carbon nanofibers in the coarse dispersion, and a back pressure is applied to the obtained dispersion. By loading and, if desired, cooling the dispersion, the carbon nanofibers can be uniformly dispersed in the solvent while suppressing the occurrence of cavitation.
When a back pressure is applied to the dispersion, the back pressure applied to the dispersion may be reduced to atmospheric pressure at a stretch, but it is preferable to reduce the pressure in multiple stages.
　ここに、粗分散液にせん断力を与えて粗分散液中の炭素ナノ繊維をさらに分散させるには、例えば、以下のような構造の分散器を有する分散システムを用いればよい。
　すなわち、分散器は、粗分散液の流入側から流出側に向かって、内径がｄ１の分散器オリフィスと、内径がｄ２の分散空間と、内径がｄ３の終端部と（但し、ｄ２＞ｄ３＞ｄ１である。）、を順次備える。
　そして、この分散器では、流入する高圧（通常、１０~４００ＭＰａ、好ましくは５０~２５０ＭＰａ）の粗分散液が、分散器オリフィスを通過することで、圧力の低下を伴いつつ、高流速の流体となって分散空間に流入する。その後、分散空間に流入した高流速の粗分散液は、分散空間内を高速で流動し、その際にせん断力を受ける。その結果、粗分散液の流速が低下すると共に、粗分散液中の炭素ナノ繊維が良好に分散する。そして、終端部から、流入した粗分散液の圧力よりも低い圧力（背圧）の流体が、分散液として流出することになる。 Here, in order to further disperse the carbon nanofibers in the coarse dispersion by applying a shearing force to the coarse dispersion, for example, a dispersion system having a disperser having the following structure may be used.
In other words, the disperser has a disperser orifice having an inner diameter d1, a dispersion space having an inner diameter d2, and a terminal portion having an inner diameter d3 from the inflow side to the outflow side of the coarse dispersion liquid (where d2>d3> d1)).
In this disperser, the inflowing high-pressure (usually 10 to 400 MPa, preferably 50 to 250 MPa) coarse dispersion passes through the disperser orifice, so that the flow rate of the fluid is reduced while the pressure decreases. And flows into the dispersion space. Thereafter, the high-velocity coarse dispersion liquid flowing into the dispersion space flows at high speed in the dispersion space and receives a shearing force at that time. As a result, the flow rate of the coarse dispersion decreases, and the carbon nanofibers in the coarse dispersion are well dispersed. Then, a fluid having a pressure (back pressure) lower than the pressure of the inflowing coarse dispersion liquid flows out from the terminal portion as the dispersion liquid.
　なお、分散液の背圧は、分散液の流れに負荷をかけることで負荷することができ、例えば、後述する多段降圧器を分散器の下流側に配設することにより、分散液に所望の背圧を負荷することができる。
　この多段降圧器により分散液の背圧を多段階で降圧することで、最終的に分散液を大気圧に開放した際に、分散液中に気泡が発生するのを抑制できる。 Note that the back pressure of the dispersion can be applied by applying a load to the flow of the dispersion. For example, a multistage step-down device described later can be provided on the downstream side of the disperser to provide a desired dispersion. Back pressure can be applied.
By reducing the back pressure of the dispersion in multiple stages using this multistage pressure reducer, it is possible to suppress the generation of bubbles in the dispersion when the dispersion is finally released to atmospheric pressure.
　また、この分散器は、分散液を冷却するための熱交換器や冷却液供給機構を備えていてもよい。というのは、分散器でせん断力を与えられて高温になった分散液を冷却することにより、分散液中で気泡が発生するのをさらに抑制できるからである。
　なお、熱交換器等の配設に替えて、粗分散液を予め冷却しておくことでも、分散液中で気泡が発生することを抑制できる。 Further, the disperser may include a heat exchanger for cooling the dispersion and a coolant supply mechanism. This is because the generation of bubbles in the dispersion can be further suppressed by cooling the dispersion that has been heated to a high temperature by the shearing force applied by the distributor.
In addition, it can suppress that a bubble generate | occur | produces in a dispersion liquid by replacing with arrangement | positioning of a heat exchanger etc. and cooling a rough dispersion liquid previously.
　上記したように、この解砕効果が得られる分散処理では、キャビテーションの発生を抑制できるので、時として懸念されるキャビテーションに起因した炭素ナノ繊維の損傷、特に、気泡が消滅する際の衝撃波に起因した炭素ナノ繊維の損傷を抑制することができる。加えて、炭素ナノ繊維への気泡の付着や、気泡の発生によるエネルギーロスを抑制して、比表面積が大きい炭素ナノ繊維であっても、均一かつ効率的に分散させることができる。
　なお、炭素ナノ繊維への気泡の付着の抑制による分散性の向上効果は、ＢＥＴ比表面積が大きい炭素ナノ繊維、特に、ＢＥＴ比表面積が６００ｍ２／ｇ以上の炭素ナノ繊維において非常に大きい。炭素ナノ繊維の比表面積が大きく、表面に気泡が付着し易い炭素ナノ繊維であるほど、気泡が発生して付着した際に分散性が低下し易いからである。 As described above, in the dispersion treatment that can obtain this crushing effect, it is possible to suppress the occurrence of cavitation, which is sometimes caused by damage to carbon nanofibers caused by cavitation, which is sometimes a concern, particularly due to shock waves when bubbles disappear. Damage to the carbon nanofibers can be suppressed. In addition, it is possible to uniformly and efficiently disperse even carbon nanofibers having a large specific surface area by suppressing the adhesion of bubbles to the carbon nanofibers and energy loss due to the generation of bubbles.
The effect of improving dispersibility by suppressing the adhesion of bubbles to the carbon nanofibers is very large in carbon nanofibers having a large BET specific surface area, particularly carbon nanofibers having a BET specific surface area of 600 m 2 / g or more. This is because the larger the specific surface area of the carbon nanofibers and the easier the carbon nanofibers to adhere to the surface, the more easily the dispersibility decreases when bubbles are generated and attached.
　以上のような構成を有する分散システムとしては、例えば、製品名「ＢＥＲＹＵ　ＳＹＳＴＥＭ　ＰＲＯ」（株式会社美粒製）に多段降圧器を組み合わせてなる分散システムなどがある。このような分散システムを用い、分散条件を適切に制御することで、分散処理を実施することができる。 As a distributed system having the above-described configuration, for example, there is a distributed system in which a product name “BERYU SYSTEM PRO” (manufactured by Migrain Co., Ltd.) is combined with a multistage step-down device. By using such a distributed system and appropriately controlling the distribution conditions, distributed processing can be performed.
＜混合液調製工程＞
　上述の炭素ナノ繊維分散工程を経て得られた炭素ナノ繊維分散液に金前躯体を添加し、必要に応じて既知の混合方法で混合することで、炭素ナノ繊維分散液および金前躯体を含む混合液を調製する。 <Mixed liquid preparation process>
A carbon nanofiber dispersion and a gold precursor are included by adding a gold precursor to the carbon nanofiber dispersion obtained through the above-described carbon nanofiber dispersion step and mixing by a known mixing method as necessary. Prepare a mixture.
−金前躯体−
　金前躯体としては、還元反応により金を生成し得る化合物が用いられる。ここで、金前躯体は、炭素ナノ繊維の表面に均一に金微粒子を担持する観点からは、用いる溶媒に溶解するものを選択して用いるのが好ましい。かかる金前躯体としては、Ｈ２［ＡｕＣｌ４］、（ＮＨ４）２［ＡｕＣｌ４］、Ｈ［Ａｕ（ＮＯ３）４］・Ｈ２Ｏ、ＮａＡｕＣｌ２・２Ｈ２Ｏ等が挙げられるが、これらに限定されるものではない。これらは、１種単独で、あるいは２種以上を組み合わせて用いることができる。そしてこれらの中でも、ＮａＡｕＣｌ２・２Ｈ２Ｏが好ましい。 -Golden body-
As the gold precursor, a compound capable of generating gold by a reduction reaction is used. Here, from the viewpoint of uniformly supporting gold fine particles on the surface of the carbon nanofiber, it is preferable to select and use a gold precursor that is soluble in the solvent to be used. Such gold precursor, H 2 [AuCl 4], (NH 4) 2 [AuCl 4], H [Au (NO 3) 4] · H 2 O, NaAuCl 2 · 2H 2 but O, and the like, It is not limited to these. These can be used singly or in combination of two or more. Of these, NaAuCl 2 .2H 2 O is preferable.
−添加量−
　金前躯体の添加量は、例えば炭素ナノ繊維の添加量の５０倍以上１０００倍以下とすることができる。金前躯体の使用量を上述の範囲内とすることで、後述する還元工程において、炭素ナノ繊維の表面に金微粒子を好適に析出させることができる。 -Addition amount-
The addition amount of the gold precursor can be, for example, 50 times or more and 1000 times or less the addition amount of the carbon nanofibers. By making the usage-amount of a gold precursor into the above-mentioned range, in the reduction | restoration process mentioned later, a gold fine particle can be suitably deposited on the surface of carbon nanofiber.
＜還元工程＞
　次に、炭素ナノ繊維分散液および金前躯体を含む混合液に還元剤を添加し、金前躯体を還元する。そして当該還元反応により炭素ナノ繊維の表面に金微粒子を析出させ、溶媒中に触媒材料が分散した触媒材料分散液を得る。なお、還元剤の混合液への添加方法は特に限定されないが、混合液に対し、還元剤を逐次添加する方法が好ましい。また還元反応を十分に進行させるべく、還元剤を添加終了後、５~３０分程度、攪拌することが好ましい。 <Reduction process>
Next, a reducing agent is added to the liquid mixture containing the carbon nanofiber dispersion and the gold precursor to reduce the gold precursor. Then, by the reduction reaction, gold fine particles are deposited on the surface of the carbon nanofibers to obtain a catalyst material dispersion liquid in which the catalyst material is dispersed in the solvent. In addition, the addition method to the liquid mixture of a reducing agent is not specifically limited, The method of adding a reducing agent to a liquid mixture sequentially is preferable. In order to allow the reduction reaction to proceed sufficiently, it is preferable to stir for about 5 to 30 minutes after the addition of the reducing agent.
−還元剤−
　還元剤としては、上述した金前躯体（金前躯体由来の陽イオン）を還元し、炭素ナノ繊維の表面に金微粒子を析出させることができるものであれば、特に限定されない。かかる還元剤としては、ギ酸、ホルムアルデヒド、ギ酸アンモニウム、ジメチルアミンボラン、ターシャリーブチルアミンボラン、トリエチルアミンボランなどが挙げられる。これらは、１種単独で、あるいは２種以上を組み合わせて用いることができる。そしてこれらの中でも、ジメチルアミンボランが好ましい。 -Reducing agent-
The reducing agent is not particularly limited as long as it can reduce the above-described gold precursor (cation derived from the gold precursor) and deposit gold fine particles on the surface of the carbon nanofiber. Examples of the reducing agent include formic acid, formaldehyde, ammonium formate, dimethylamine borane, tertiary butylamine borane, and triethylamine borane. These can be used singly or in combination of two or more. Of these, dimethylamine borane is preferred.
−添加量−
　還元剤の添加量は、例えば金前躯体の添加量の０．０１倍以上１倍以下とすることができる。還元剤の使用量を上述の範囲内とすることで、還元反応を良好に進行させ、炭素ナノ繊維の表面に金微粒子を好適に析出させることができる。 -Addition amount-
The addition amount of a reducing agent can be 0.01 times or more and 1 time or less of the addition amount of a gold precursor, for example. By making the usage-amount of a reducing agent into the above-mentioned range, a reduction reaction can be advanced favorable and gold fine particles can be deposited suitably on the surface of carbon nanofiber.
＜触媒材料分離工程＞
　そして、上記還元工程を経て得られた触媒材料分散液から、例えばろ過や遠心分離など、好ましくはろ過により触媒材料を得ることができる。また得られた触媒材料は、必要に応じて、当該触媒材料に付着したイオン性界面活性剤および高分子系界面活性剤などを除去すべく洗浄したり、不要な溶媒を除去すべく乾燥したりしてもよい。 <Catalyst material separation process>
A catalyst material can be obtained from the catalyst material dispersion obtained through the reduction step, for example, by filtration or centrifugation, preferably by filtration. In addition, the obtained catalyst material may be washed to remove ionic surfactants and polymer surfactants attached to the catalyst material, or dried to remove unnecessary solvents, if necessary. May be.
　以下、本発明について実施例に基づき具体的に説明するが、本発明はこれら実施例に限定されるものではない。
　なお、実施例において使用した炭素ナノ繊維としてのカーボンナノチューブは、以下の方法で合成した。また、調製した触媒材料の評価は、以下の方法を使用して行った。 EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
In addition, the carbon nanotube as a carbon nanofiber used in the Example was synthesize | combined with the following method. Moreover, evaluation of the prepared catalyst material was performed using the following method.
（カーボンナノチューブの合成）
＜合成例１：ＳＧＣＮＴ−１の合成＞
　国際公開第２００６／０１１６５５号の記載に従い、スーパーグロース法によりＣＮＴ（ＳＧＣＮＴ−１）を調製した。なお、ＳＧＣＮＴ−１の調製時には、基材表面への触媒層（鉄薄膜）の形成をウェットプロセスにより行い、アセチレンを主成分とする原料ガスを用いた。
　得られたＳＧＣＮＴ−１は、ＢＥＴ比表面積が１０５０ｍ２／ｇ（未開口）、マイクロ孔容積が０．４５ｍＬ／ｇであり、ラマン分光光度計での測定において、単層ＣＮＴに特長的な１００~３００ｃｍ−１の低波数領域にラジアルブリージングモード（ＲＢＭ）のスペクトルが観察された。また、透過型電子顕微鏡を用い、無作為に１００本のＳＧＣＮＴ−１の直径および長さを測定した結果、平均直径（Ａｖ）が３．３ｎｍ、直径の標準偏差（σ）に３を乗じた値（３σ）が１．９ｎｍ、それらの比（３σ／Ａｖ）が０．５８であった。
＜合成例２：ＳＧＣＮＴ−２の合成＞
　触媒層（鉄薄膜）の厚みを変えたこと以外は、合成例１と同様にして、ＳＧＣＮＴ−２を調製した。
　得られたＳＧＣＮＴ−２は、ＢＥＴ比表面積が８６０ｍ２／ｇ（未開口）、マイクロ孔容積が０．４１ｍＬ／ｇであり、ラマン分光光度計での測定において、単層ＣＮＴに特長的な１００~３００ｃｍ−１の低波数領域にラジアルブリージングモード（ＲＢＭ）のスペクトルが観察された。また、透過型電子顕微鏡を用い、無作為に１００本のＳＧＣＮＴ−２の直径および長さを測定した結果、平均直径（Ａｖ）が４．６ｎｍ、直径の標準偏差（σ）に３を乗じた値（３σ）が２．３ｎｍ、それらの比（３σ／Ａｖ）が０．５０であった。
＜合成例３：表面処理ＳＧＣＮＴ−２＞
　上記ＳＧＣＮＴ−２に、気相プラズマ処理（プラズマ発生ガス：窒素、処理時間：５分）を施し、表面処理ＳＧＣＮＴ−２を調製した。なお、表面処理ＳＧＣＮＴ−２の平均直径（Ａｖ）、直径の標準偏差（σ）、３σ／Ａｖは、表面処理前の値と同じであった。 (Synthesis of carbon nanotubes)
<Synthesis Example 1: Synthesis of SGCNT-1>
CNT (SGCNT-1) was prepared by the super-growth method according to the description in International Publication No. 2006/011655. At the time of preparing SGCNT-1, the catalyst layer (iron thin film) was formed on the surface of the substrate by a wet process, and a raw material gas mainly composed of acetylene was used.
The obtained SGCNT-1 has a BET specific surface area of 1050 m 2 / g (unopened) and a micropore volume of 0.45 mL / g, and is characteristic of single-walled CNT in measurement with a Raman spectrophotometer. A spectrum of radial breathing mode (RBM) was observed in the low wavenumber region of ˜300 cm −1 . Moreover, as a result of measuring the diameter and length of 100 SGCNT-1 at random using a transmission electron microscope, the average diameter (Av) was 3.3 nm and the standard deviation (σ) of the diameter was multiplied by 3. The value (3σ) was 1.9 nm, and the ratio (3σ / Av) was 0.58.
<Synthesis Example 2: Synthesis of SGCNT-2>
SGCNT-2 was prepared in the same manner as in Synthesis Example 1 except that the thickness of the catalyst layer (iron thin film) was changed.
The obtained SGCNT-2 has a BET specific surface area of 860 m 2 / g (unopened) and a micropore volume of 0.41 mL / g, and is characteristic of single-walled CNT in measurement with a Raman spectrophotometer. A spectrum of radial breathing mode (RBM) was observed in the low wavenumber region of ˜300 cm −1 . Moreover, as a result of measuring the diameter and length of 100 SGCNT-2 at random using a transmission electron microscope, the average diameter (Av) was 4.6 nm and the standard deviation (σ) of the diameter was multiplied by 3. The value (3σ) was 2.3 nm and the ratio (3σ / Av) was 0.50.
<Synthesis Example 3: Surface Treatment SGCNT-2>
The SGCNT-2 was subjected to gas phase plasma treatment (plasma generating gas: nitrogen, treatment time: 5 minutes) to prepare surface-treated SGCNT-2. The average diameter (Av), the standard deviation of diameter (σ), and 3σ / Av of the surface-treated SGCNT-2 were the same as the values before the surface treatment.
（触媒材料の触媒活性評価）
　５０ｇ／Ｌのグルコース水溶液５０ｍｌを３０℃に調温し、スターラーで撹拌しながら、得られた触媒材料を（グルコース）／（触媒材料に担持された金）のモル比が６４０／１となるように添加した。なお、触媒材料に担持された金の量は、触媒材料の還元工程前後の液中の金イオン濃度の減少幅に基づいて算出することができる。そして、酸素をバブリングしながら、０．１Ｎの水酸化カリウム水溶液を添加してｐＨが９になるように調整した。ｐＨ調整後、得られた混合液を６時間攪拌した。攪拌後、吸引ろ過により触媒材料を回収し、ろ液を得た。このろ液を８０℃に調温し、スターラーで撹拌しながらフェーリング液（６９．２ｇ／Ｌの硫酸銅五水和物水溶液５０ｍｌと、３６４ｇ／Ｌの濃度で酒石酸カリウムナトリウムが、１００ｇ／Ｌの濃度で水酸化ナトリウムがそれぞれ溶解した水溶液５０ｍＬとを混合することにより調製）を加え、当該フェーリング液の添加後、３０分間攪拌を継続した。その後、吸引ろ過により得られた亜酸化銅を回収し、その重量Ｘを測定した。
　また、触媒材料に替えて、当該触媒材料の製造に使用した炭素ナノ繊維を、触媒材料の量と同量で使用した以外は、上述の操作と同様の操作を行うことで、得られる亜酸化銅を回収し、その重量Ｙを測定した。
　以下の式により、反応率（％）を算出し、触媒材料のグルコース酸化における触媒活性の指標とした。当該反応率の値が大きいほどグルコースが酸化されており、触媒材料がグルコース酸化の触媒活性に優れていることを示す。
　反応率（％）＝（１−Ｘ／Ｙ）×１００ (Evaluation of catalytic activity of catalyst materials)
50 ml of 50 g / L aqueous glucose solution was adjusted to 30 ° C. and stirred with a stirrer so that the resulting catalyst material had a molar ratio of (glucose) / (gold supported on the catalyst material) of 640/1. Added to. The amount of gold supported on the catalyst material can be calculated based on the amount of decrease in the gold ion concentration in the liquid before and after the reduction process of the catalyst material. Then, while bubbling oxygen, an aqueous 0.1N potassium hydroxide solution was added to adjust the pH to 9. After pH adjustment, the resulting mixture was stirred for 6 hours. After stirring, the catalyst material was recovered by suction filtration to obtain a filtrate. The filtrate was adjusted to 80 ° C., and stirred with a stirrer. A Ferring solution (69.2 g / L copper sulfate pentahydrate aqueous solution, 50 mg potassium potassium tartrate at a concentration of 364 g / L, 100 g / L (Prepared by mixing 50 mL of an aqueous solution in which sodium hydroxide was dissolved in each concentration), and stirring was continued for 30 minutes after the addition of the failing solution. Thereafter, cuprous oxide obtained by suction filtration was recovered, and its weight X was measured.
Also, sub-oxidation obtained by performing the same operation as described above, except that the carbon nanofibers used for the production of the catalyst material were used in the same amount as the amount of the catalyst material instead of the catalyst material. Copper was recovered and its weight Y was measured.
The reaction rate (%) was calculated by the following formula, and used as an index of the catalytic activity in the glucose oxidation of the catalyst material. As the value of the reaction rate is larger, glucose is oxidized, indicating that the catalyst material is excellent in the catalytic activity of glucose oxidation.
Reaction rate (%) = (1−X / Y) × 100
（実施例１）
　炭素ナノ繊維としてのＳＧＣＮＴ−１を０．０１ｇ、イオン性界面活性剤としてのドデシル硫酸ナトリウム（ＳＤＳ）および高分子系界面活性剤としてのヒドロキシプロピルセルロース（ＨＰＣ）の濃度がそれぞれ１ｇ／Ｌの水溶液１Ｌに加え、３０分間スターラーを用いて撹拌して粗分散液を得た。この粗分散液に対し、キャビテーション効果を利用した分散装置であるジェットミル（常光社製、製品名「ＪＮ−２０」）を用いて、５０ＭＰａの条件にて２０回分散処理を行うことにより、ＳＧＣＮＴ−１を含む分散液（炭素ナノ繊維分散液）を得た。次いで、金前躯体としてのＮａＡｕＣｌ２・２Ｈ２Ｏ　０．０１２５ｍｏｌ／Ｌの水溶液４０ｍｌ（ＮａＡｕＣｌ２が０．１４５ｇ相当）に、前記炭素ナノ繊維分散液を含む分散液を４０ｍｌ（ＳＧＣＮＴ−１が０．０００４ｇ、ＳＤＳが０．０４ｇ、ＨＰＣが０．０４ｇ相当）加え、３０分間スターラーを用いて撹拌し、混合液を得た。その後、還元剤としてのジメチルアミンボランの０．０２５ｍｏｌ／Ｌ水溶液１０ｍｌ（ジメチルアミンボランが０．０１４７ｇ相当）を、金前躯体と炭素ナノ繊維が混在した前記混合液（３０℃）に２分間かけて滴下し、滴下終了後、さらに８分間スターラーを用いて撹拌し、触媒材料分散液を得た。この触媒材料分散液を透過型電子顕微鏡（ＴＥＭ）で観察したところ、金微粒子（平均粒径：８ｎｍ）が単層のＣＮＴ構造体（ＳＷＣＮＴ）に担持されている触媒材料１が観察された。次いで、この触媒材料分散液を吸引ろ過し、当該分散液から触媒材料１を容易に分離することができた。この触媒材料１の反応率（％）は２７．９％であり、グルコース酸化に対して高い触媒活性を示すことが確認された。 (Example 1)
An aqueous solution containing 0.01 g of SGCNT-1 as carbon nanofibers, sodium dodecyl sulfate (SDS) as an ionic surfactant, and hydroxypropyl cellulose (HPC) as a polymeric surfactant, each at a concentration of 1 g / L. In addition to 1 L, the mixture was stirred with a stirrer for 30 minutes to obtain a crude dispersion. SGCNT is obtained by subjecting this coarse dispersion to a dispersion process 20 times under the condition of 50 MPa using a jet mill (manufactured by Joko Co., Ltd., product name “JN-20”), which is a dispersion apparatus utilizing the cavitation effect. -1 containing dispersion (carbon nanofiber dispersion) was obtained. Next, 40 ml of a dispersion containing the carbon nanofiber dispersion is added to 40 ml of an aqueous solution of NaAuCl 2 .2H 2 O 0.0125 mol / L as a gold precursor (corresponding to 0.145 g of NaAuCl 2 ). 0004 g, SDS 0.04 g, and HPC 0.04 g), and stirred for 30 minutes using a stirrer to obtain a mixed solution. Thereafter, 10 ml of a 0.025 mol / L aqueous solution of dimethylamine borane as a reducing agent (dimethylamine borane is equivalent to 0.0147 g) is applied to the mixed solution (30 ° C.) in which the gold precursor and carbon nanofibers are mixed for 2 minutes. After the completion of dropping, the mixture was further stirred for 8 minutes using a stirrer to obtain a catalyst material dispersion. When this catalyst material dispersion was observed with a transmission electron microscope (TEM), catalyst material 1 in which gold fine particles (average particle size: 8 nm) were supported on a single-walled CNT structure (SWCNT) was observed. Subsequently, this catalyst material dispersion was subjected to suction filtration, and the catalyst material 1 could be easily separated from the dispersion. The reaction rate (%) of the catalyst material 1 was 27.9%, and it was confirmed that the catalyst material 1 showed high catalytic activity for glucose oxidation.
（実施例２）
　炭素ナノ繊維としてのＳＧＣＮＴ−１に替えてＳＧＣＮＴ−２を使用し、そして、分散処理として、キャビテーション効果が得られる分散処理に替えて、製品名「ＢＥＲＹＵ　ＳＹＳＴＥＭ　ＰＲＯ」（株式会社美粒製）に多段降圧器を組み合わせてなる分散システムを用いて解砕効果が得られる分散処理を施した以外は、実施例１と同様にして触媒材料２を得た。当該触媒材料２を含む触媒材料分散液を透過型電子顕微鏡（ＴＥＭ）で観察したところ、金微粒子（平均粒径：９ｎｍ）が単層のＣＮＴ構造体（ＳＷＣＮＴ）に担持されている触媒材料２が観察された（図１参照、なお図１および後述する図２においては、ＳＷＣＮＴの輪郭の把握を容易とすべく、輪郭を表示する補助線を追加している）。この触媒材料２の反応率（％）は２６．８％であり、グルコース酸化に対して高い触媒活性を示すことが確認された。 (Example 2)
SGCNT-2 is used instead of SGCNT-1 as the carbon nanofiber, and the product name “BERYU SYSTEM PRO” (manufactured by Miebu Co., Ltd.) is used instead of the dispersion treatment for obtaining a cavitation effect as the dispersion treatment. A catalyst material 2 was obtained in the same manner as in Example 1 except that a dispersion treatment that can provide a crushing effect was performed using a dispersion system that is a combination of multistage step down devices. When the catalyst material dispersion containing the catalyst material 2 is observed with a transmission electron microscope (TEM), the catalyst material 2 in which gold fine particles (average particle diameter: 9 nm) are supported on a single-walled CNT structure (SWCNT). Was observed (see FIG. 1, and in FIG. 1 and FIG. 2 described later, an auxiliary line for displaying the contour is added to facilitate understanding of the contour of the SWCNT). The reaction rate (%) of the catalyst material 2 was 26.8%, and it was confirmed that the catalyst material 2 showed high catalytic activity for glucose oxidation.
（実施例３）
　炭素ナノ繊維としてのＳＧＣＮＴ−２に替えて、表面処理ＳＧＣＮＴ−２を使用した以外は、実施例２と同様にして触媒材料３を得た。当該触媒材料３を含む触媒材料分散液を透過型電子顕微鏡（ＴＥＭ）で観察したところ、金微粒子（平均粒径：６ｎｍ）が単層のＣＮＴ構造体（ＳＷＣＮＴ）に担持されている触媒材料３が観察された（図２参照）。この触媒材料３の反応率（％）は２８．９％であり、グルコース酸化に対して高い触媒活性を示すことが確認された。 (Example 3)
Catalyst material 3 was obtained in the same manner as in Example 2 except that surface-treated SGCNT-2 was used instead of SGCNT-2 as the carbon nanofiber. When the catalyst material dispersion containing the catalyst material 3 is observed with a transmission electron microscope (TEM), the catalyst material 3 in which gold fine particles (average particle diameter: 6 nm) are supported on a single-walled CNT structure (SWCNT). Was observed (see FIG. 2). The reaction rate (%) of the catalyst material 3 was 28.9%, and it was confirmed that the catalyst material 3 showed high catalytic activity for glucose oxidation.
（比較例１）
　炭素ナノ繊維としてのＳＧＣＮＴ−１に替えて、多層カーボンナノチューブ（ＭＷＣＮＴ；Ｎａｎｏｃｙｌ社製、製品名「ＮＣ７０００」、ＢＥＴ比表面積：２９０ｍ２／ｇ、平均直径：９．３ｎｍ）を使用した以外は、実施例１と同様にして比較例触媒材料１を得た。当該比較例触媒材料１を含む触媒材料分散液を透過型電子顕微鏡（ＴＥＭ）で観察したところ、金微粒子（平均粒径：１８ｎｍ）が多層ＣＮＴ構造体（ＭＷＣＮＴ）に担持されている比較例触媒材料１が観察された。この比較例触媒材料１の反応率（％）は２１．５％であり、実施例１~３に比してグルコース酸化に対する触媒活性が劣ることが確認された。 (Comparative Example 1)
Instead of SGCNT-1 as the carbon nanofiber, except that multi-walled carbon nanotubes (MWCNT; manufactured by Nanocyl, product name “NC7000”, BET specific surface area: 290 m 2 / g, average diameter: 9.3 nm) were used. Comparative Example Catalyst Material 1 was obtained in the same manner as Example 1. When the catalyst material dispersion containing the comparative catalyst material 1 is observed with a transmission electron microscope (TEM), a comparative catalyst in which gold fine particles (average particle diameter: 18 nm) are supported on a multilayer CNT structure (MWCNT) Material 1 was observed. The reaction rate (%) of the comparative catalyst material 1 was 21.5%, and it was confirmed that the catalytic activity for glucose oxidation was inferior to that of Examples 1 to 3.
　本発明によれば、金微粒子が担持された、触媒活性に優れる触媒材料を提供することができる。
　また、本発明によれば、金微粒子が担持された、触媒活性に優れる触媒材料の製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the catalyst material which was carrying | supported the gold fine particle and was excellent in catalyst activity can be provided.
Moreover, according to this invention, the manufacturing method of the catalyst material which was carrying | supported the gold fine particle and was excellent in catalytic activity can be provided.

Claims (5)

  1. 　平均直径（Ａｖ）が５ｎｍ以下の炭素ナノ繊維に金微粒子が担持されてなる触媒材料。 Catalyst material in which gold fine particles are supported on carbon nanofibers having an average diameter (Av) of 5 nm or less.
  2. 　前記炭素ナノ繊維が、平均直径（Ａｖ）と直径の標準偏差（σ）とが、関係式：０．２０＜（３σ／Ａｖ）＜０．６０を満たすカーボンナノチューブである、請求項１に記載の触媒材料。 The carbon nanofiber is a carbon nanotube in which an average diameter (Av) and a standard deviation (σ) of a diameter satisfy a relational expression: 0.20 <(3σ / Av) <0.60. Catalyst material.
  3. 　前記炭素ナノ繊維は、気相プラズマ処理が施されている、請求項１または２に記載の触媒材料。 The catalyst material according to claim 1 or 2, wherein the carbon nanofibers are subjected to gas phase plasma treatment.
  4. 　前記金微粒子の平均粒径が２ｎｍ以上１０ｎｍ以下である、請求項１~３の何れかに記載の触媒材料。 4. The catalyst material according to claim 1, wherein an average particle diameter of the gold fine particles is 2 nm or more and 10 nm or less.
  5. 　請求項１~４の何れかに記載の触媒材料の製造方法であって、
    　平均直径（Ａｖ）が５ｎｍ以下の炭素ナノ繊維を、イオン性界面活性剤および高分子系界面活性剤の存在下で、キャビテーション効果または解砕効果が得られる分散処理によって溶媒に分散させる工程を含む、触媒材料の製造方法。     A method for producing a catalyst material according to any one of claims 1 to 4,
    Including a step of dispersing carbon nanofibers having an average diameter (Av) of 5 nm or less in a solvent in the presence of an ionic surfactant and a polymeric surfactant by a dispersion treatment capable of obtaining a cavitation effect or a crushing effect. And a method for producing a catalyst material.
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