WO2010082443A1 - Poudre de noir de platine, colloïde de noir de platine, procédé de production de poudre de noir de platine, et procédé pour la production de colloïde de noir de platine - Google Patents

Poudre de noir de platine, colloïde de noir de platine, procédé de production de poudre de noir de platine, et procédé pour la production de colloïde de noir de platine Download PDF

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WO2010082443A1
WO2010082443A1 PCT/JP2009/071740 JP2009071740W WO2010082443A1 WO 2010082443 A1 WO2010082443 A1 WO 2010082443A1 JP 2009071740 W JP2009071740 W JP 2009071740W WO 2010082443 A1 WO2010082443 A1 WO 2010082443A1
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platinum
platinum black
colloid
nanocolloid
black powder
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Japanese (ja)
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賢 伊藤
吉朗 杉田
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株式会社フルヤ金属
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/613—10-100 m2/g
    • 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
    • B01J37/12—Oxidising
    • B01J37/14—Oxidising with gases containing free oxygen
    • 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
    • B01J37/16—Reducing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
    • H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a high specific surface area platinum black powder having high catalytic activity, a platinum black colloid, and a method for producing them.
  • Platinum platinum has long been used as a hydrogenation catalyst or oxidation catalyst for fin chemicals. In recent years, it has been used as a catalyst for gas diffusion electrodes in applications of fuel cells, electrolytic cells, and electrochemical sensors.
  • platinum black has been pointed out as having the following merits that the supported platinum catalyst does not have. That is, (1) platinum utilization efficiency is improved because platinum nanoparticles as active species are not embedded in the pores of the support, and (2) the supported catalyst may corrode or deteriorate the support depending on the reaction conditions. This may promote the aggregation of the supported platinum nanoparticles, but platinum black does not have these fears, and (3) the catalyst layer thickness is particularly important for electrode catalyst applications. Since it can be formed much thinner than the above case, it is possible to improve material transport and to localize the catalyst layer in the vicinity of the electrolyte membrane, so that a high-performance electrode can be formed.
  • platinum black and the BET specific surface area (hereinafter also referred to as “specific surface area”) of platinum black obtained by the production method have been many reports on the production method of platinum black and the BET specific surface area (hereinafter also referred to as “specific surface area”) of platinum black obtained by the production method.
  • platinum black having a specific surface area of 8 m 2 / g is obtained by reducing formal solution of H 2 PtCl 6 aqueous solution at room temperature in the presence of concentrated KOH aqueous solution (see, for example, Non-Patent Document 1).
  • Non-Patent Document 3 After adding excess deionized water to a dilute nitric acid solution of hexahydroxoplatinum (IV) acid, the mixture was heated to 70 ° C. to obtain an orange suspension of platinum dioxide, and concentrated ammonia water was added thereto to adjust the pH to 5 And then reduced with formic acid to obtain platinum black having a crystallite size of 5.3 nm (for example, see Patent Document 1).
  • Patent Document 2 The platinum dioxide powder obtained after washing is dispersed in water, and 3% NaOH and 6% hydrazine aqueous solution A method for obtaining platinum black having a specific surface area of 47 to 52 m 2 / g by reduction is reported (for example, see Patent Document 2).
  • Patent Document 2 also describes that an alloy powder having a specific surface area of 84 to 87 m 2 / g and an atomic ratio of platinum and ruthenium of 50:50 can be obtained by the same melting method as described above.
  • Non Patent Document 1 specific surface area as described above is that 8m 2 / g, in Non-Patent Document 2 specific surface area of 22.2 ⁇ 31.7m 2 / g, Non Patent Document 3 a specific surface area of 10 m 2 / g.
  • Patent Document 2 describes an alloy powder of platinum and ruthenium having a specific surface area of 84 to 87 m 2 / g, but does not describe a production example of platinum powder having a high specific surface area exceeding 70 m 2 / g. .
  • Patent Document 2 can read the description of platinum black with a high specific surface area formally, but Pt-Ru alloy is the main invention and has a high specific surface area exceeding 70 m 2 / g. Examples of platinum black are not taught.
  • an object of the present invention is to provide a highly active platinum black catalyst powder having a high specific surface area exceeding 70 m 2 / g, a colloid in which it is dispersed, and a practical production method thereof.
  • the present inventors have found that platinum black having a high specific surface area can be obtained by using a nanocolloid of hexahydroxoplatinic acid as a production intermediate. Completed. That is, the platinum black powder according to the present invention has a specific surface area of 80 m 2 / g or more. Furthermore, the platinum black powder according to the present invention is characterized by having a specific surface area of 90 m 2 / g or more. The platinum black powder according to the present invention is characterized in that the total pore volume is 0.038 cm 3 / g or more.
  • the content of oxygen in terms of dry mass by elemental analysis is 3.5% by mass or more and 7.0% by mass or less.
  • the dry mass conversion contents of chlorine and alkali metal contained as impurities by elemental analysis are both 500 ppm or less.
  • the platinum-containing species detected by powder X-ray diffraction is only cubic platinum, and the Pt (220) crystallite size is 3.0 nm or less.
  • the colloid of platinum black according to the present invention is a colloid of platinum black in which the platinum black powder according to the present invention is dispersed in a protic polar solvent, and has a particle diameter of 0.1 nm or more measured by a dynamic light scattering method.
  • the particle size distribution in the region of 10,000 nm has a particle size distribution curve having a single peak, an average particle size of 250 nm or less, and a polydispersity index of 0.15 or less.
  • the platinum black colloid according to the present invention preferably has a zeta potential of minus 40 mV or less.
  • the method for producing a platinum black powder according to the present invention includes a nanocolloid generation step of generating a nanocolloid of hexahydroxoplatinic acid in a liquid phase, a reducing agent added to the nanocolloid to reduce the nanocolloid, A reduction step of forming a colloid-containing colloid, a washing step of filtering the platinum-containing colloid and washing with pure water, a drying step of drying the washed platinum-containing colloid, It is characterized by having.
  • the method for producing platinum black powder according to the present invention preferably further includes an oxygen treatment step of blowing air or oxygen gas into the platinum-containing colloid after the reduction step.
  • the method for producing a platinum black colloid according to the present invention includes a nanocolloid generating step of generating a nanocolloid of hexahydroxoplatinic acid in a liquid phase, a reducing agent added to the nanocolloid to reduce the nanocolloid, A reduction step of forming a colloid containing, a washing step of filtering the platinum-containing colloid and washing with pure water, and a dispersion step of dispersing the washed platinum-containing colloid in a solvent.
  • the method for producing a platinum black colloid according to the present invention preferably further includes an oxygen treatment step of blowing air or oxygen gas into the platinum-containing colloid after the reduction step.
  • the platinum black powder according to the present invention has a high specific surface area exceeding 70 m 2 / g, as the highly active platinum black catalyst powder, the above-mentioned potential merit, that is, (1) platinum nanoparticles which are active species are The platinum utilization efficiency can be improved because it is not embedded in the pores of the support, and (2) platinum black has high resistance to corrosion and deterioration even under reaction conditions where the support of the supported catalyst corrodes and deteriorates. (3) Especially in the use of an electrocatalyst, the thickness of the catalyst layer can be significantly reduced compared to the case of the supported catalyst, so that mass transport is improved and the catalyst layer can be localized in the vicinity of the electrolyte membrane. Therefore, it is possible to form a high-performance electrode.
  • the method for producing platinum black powder according to the present invention can provide a high specific surface area exceeding 70 m 2 / g.
  • the platinum black according to the present invention is easily dispersed in a protic polar solvent, and the thus obtained platinum black colloid of the present invention has a high absolute value of zeta potential and a sharp particle size distribution, and therefore has high stability as a colloid.
  • FIG. 2 is an observation image of platinum black obtained in Example 1 with a transmission electron microscope TEM.
  • the method for producing platinum black powder according to the present embodiment includes a nanocolloid generation step of forming a nanocolloid of hexahydroxoplatinic acid in a liquid phase, and a nanocolloid obtained by adding a reducing agent to the nanocolloid.
  • a reduction step of reducing and forming a platinum-containing colloid a washing step of filtering the platinum-containing colloid and washing with pure water, and a drying step of drying the washed platinum-containing colloid.
  • Hexahydroxoplatinic acid used in this step is a known substance, and a method for producing hexahydroxoplatinic acid is also known as taught in Patent Document 3 or 4. It is also known that hexahydroxoplatinic acid is dissolved in an amine solution and solubilized, as taught by Patent Document 5, 6 or 7.
  • the hexahydroxoplatinic acid nanocolloid is prepared by preparing an amine solution of hexahydroxoplatinic acid or a dilute solution of sodium or potassium salt of hexahydroxoplatinic acid and adding a dilute solution of the neutralizing agent dropwise or while stirring vigorously. Obtained by spray addition.
  • An amine solution of hexahydroxoplatinic acid is preferable.
  • it can be obtained by adding dropwise or spraying a dilute solution of hexahydroxoplatinic acid or a dilute solution of sodium salt or potassium salt of hexahydroxoplatinate to a dilute solution of the neutralizing agent sufficiently vigorously.
  • An amine solution of hexahydroxoplatinic acid is preferable.
  • the sufficiently vigorous stirring is stirring in a state where the liquid level of the reaction solution is undulating, and the rotation speed of the stirring bar or the stirring blade is usually 100 rpm to 400 rpm, preferably 250 rpm to 350 rpm.
  • neutralizing agent various acids are used, and preferred are carboxylic acids such as acetic acid and propionic acid, or nitric acid.
  • carboxylic acids such as acetic acid and propionic acid, or nitric acid.
  • Various amines are used as the amine, and 2-ethanolamine is preferred.
  • solvent various solvents such as water, methanol and ethanol are used, and water is preferred.
  • the conditions for dropping are room temperature of about 15 ° C. to 30 ° C., and the dropping time is usually about 10 minutes to 3 hours, preferably 20 minutes to 1 hour.
  • the interval of dropping is usually 1 to 60 seconds, preferably 5 to 20 seconds, depending on the diameter of the droplets. Instead of dropping, it may be added by spraying from a spray nozzle at a corresponding flow rate.
  • the concentration of the substrate in the stirred reaction solution is usually 0.1 mmol / L to 50 mmol / L, preferably 1 mmol / L to 20 mmol / L, and the concentration of the other substrate added dropwise is usually 1 mmol / L to 1 mol / L, preferably 10 mmol / L to 200 mmol / L.
  • the amount of the neutralizing agent to be used is selected so that the pH at the end of dropping is substantially neutral, that is, usually 5.3 to 8.0, preferably 5.7 to 7.8.
  • the primary particle size of the resulting hexahydroxoplatinic acid nanocolloid is usually 0.5 nm to 3.0 nm, preferably 0.5 nm to 2.0 nm.
  • the secondary particle size is usually 50 to 200 nm, preferably 50 to 100 nm.
  • the primary particle diameter of the colloid refers to the number average particle diameter determined by morphological observation with a high-resolution transmission electron microscope (TEM) or a field emission scanning electron microscope (FE-SEM).
  • TEM transmission electron microscope
  • FE-SEM field emission scanning electron microscope
  • the crystallite size determined by powder method X diffraction is usually almost the same as the primary particle size observed with these electron microscopes.
  • the particle size distribution of the secondary particles of the colloid is measured by a dynamic light scattering (DPS) method, and Z-Average and PDI obtained by the photon correlation method are used as the average particle size and polydispersity coefficient.
  • DPS dynamic light scattering
  • Reduction process In this step, a reducing agent is added to the hexahydroxoplatinic acid nanocolloid obtained in the nanocolloid production step to reduce IV valent platinum to zero valence.
  • the reducing agent conventionally known liquid phase reducing agents such as formalin, formic acid, hydrazine hydrate, citric acid, ascorbic acid and hydrogen-containing gas bubbling into the colloid are used, but formic acid is preferred.
  • the conditions for the reduction reaction are the conditions under which the hexahydroxoplatinic acid nanocolloid obtained in the nanocolloid production step is reduced to zero and the produced platinum nanocolloid does not aggregate depending on the type and concentration of the reducing agent used. select.
  • the concentration of the reducing agent in the reducing agent solution is usually 10 mmol / L to 10 mol / L, preferably 100 mmol / L to 1.0 mol / L.
  • the atmosphere at the time of adding a liquid phase reducing agent it is preferable to carry out by the open air system or oxygen-containing gas atmosphere, for example, the circulation of synthetic air.
  • the open air system or oxygen-containing gas atmosphere for example, the circulation of synthetic air.
  • the specific surface area may be suppressed.
  • the reducing agent is a hydrogen-containing gas
  • the hydrogen concentration is usually 1% to 100%, preferably 10% to 50%, and the balance is nitrogen, argon or helium, preferably nitrogen.
  • the reaction temperature in the reduction step is usually 4 ° C to 100 ° C, preferably 20 ° C to 98 ° C.
  • the amount of the reducing agent to be added is usually 0.5 to 2.0 equivalents, preferably 0.7 to 1.5 equivalents, relative to the stoichiometric amount necessary for reducing IV valent platinum to zero valence. is there.
  • the time required for the addition of the reducing agent is usually 5 minutes to 4 hours, preferably 20 minutes to 2 hours.
  • the interval of dropping depends on the diameter of the droplet, but is usually every 1 to 60 seconds, preferably every 5 to 20 seconds. Instead of dripping, spray addition may be performed at a corresponding addition rate using a spray nozzle.
  • the reduction reaction holding time for maintaining stirring at a constant temperature after the addition is usually 5 minutes to 24 hours, preferably 20 minutes to 8 hours.
  • the degree of progress of the reduction reaction can be followed by a change in color tone, in which the milky white color of the first colloidal hexahydroxoplatinic acid gradually turns gray and finally turns to black black.
  • the platinum-containing colloid obtained in the reduction step is filtered and washed with pure water.
  • a membrane filter having a maximum passing particle size of 0.1 to 0.2 ⁇ m is used to prevent filtration leakage of the nanoparticles.
  • the post-filtration cake has an electrical conductivity of 1 ⁇ s / cm or less, preferably 0.8 ⁇ s / cm or less, in deionized water or ultrapure water, preferably the same temperature water, and the filtrate has a conductivity of 2.0 ⁇ s / cm or less, preferably Wash until 1.0 ⁇ s / cm or less.
  • the washed platinum-containing colloid is dried. Specifically, the washed filter cake is sucked and air-dried in the air, and dried to a moisture content of 45% or less, preferably 42 to 35%. If it is air-dried to a moisture content of 45% or less, it can be scraped off from filter paper, weighed with a medicine basket, or handled as a powder. If the moisture content is higher than 45%, it becomes a viscous mud and may be difficult to handle.
  • the high specific surface area platinum black of the present invention has high activity, and it is preferable to store it in such a wet cake in order to avoid the risk of ignition due to drying.
  • the solid after air drying may be further dried to a moisture content of about 4% in a dryer or desiccator.
  • a change in moisture content with time can be almost ignored, and storage and handling are easy, but care must be taken in managing the drying conditions.
  • drying in air is preferable.
  • the drying temperature is as low as possible in order to prevent aggregation of platinum particles. Preferably it is 80 degrees C or less, More preferably, it is 60 degrees C or less.
  • the final moisture content is preferably not less than the moisture content equivalent to the total pore volume of the platinum black of the present invention.
  • the lower limit of the preferable moisture content of platinum black having a total pore volume of 0.04 cm 3 / g is 4% by mass. Drying more than this may cause fire during handling.
  • an oxygen treatment step of blowing air or oxygen gas into the platinum-containing colloid after the reduction step is an additional step for obtaining a more preferable production method, and air or oxygen gas is blown into the platinum-containing colloid obtained in the reduction step to highly disperse the platinum nanoparticles.
  • air or oxygen gas is introduced into the liquid, for example, at a flow rate of 100 mL / min to 10 L / min, preferably at a flow rate of 200 mL / min to 2 L / min, for example, 10 minutes. Blow for ⁇ 4 hours, preferably 20 minutes to 2 hours. Then, it progresses to a washing process and a drying process.
  • the blowing of air or oxygen gas is performed at, for example, a liquid temperature of 4 ° C. to 100 ° C., preferably a liquid temperature of 15 ° C. to 60 ° C., more preferably 20 ° C. to 40 ° C.
  • an inert gas such as nitrogen or argon gas
  • hydrogen gas is blown in, the specific surface area may be significantly reduced.
  • the effect of increasing the specific surface area of platinum black by the contact of platinum-containing colloids with air or oxygen gas is that the specific surface area of wet black platinum black with a moisture content of about 40% after cleaning and air-drying is from 1 month to 6 months.
  • a platinum black powder manufacturing method (first embodiment) according to the present embodiment a platinum black powder having a BET specific surface area of 80 m 2 / g or more is obtained. Furthermore, according to the production method (second embodiment) in which an oxygen treatment step is additionally added, a platinum black powder having a BET specific surface area of 90 m 2 / g or more is easily obtained.
  • the specific surface area of platinum black in the production method of the present invention is reduced by reducing the primary particle size of the intermediate hexahydroxoplatinic acid nanocolloid from 0.5 nm to 2.0 nm without growing as much as possible to platinum black.
  • the platinum black powder whose total pore volume is 0.038 cm ⁇ 3 > / g or more is obtained.
  • the total pore volume is 0.040 cm 3 / g or more.
  • the content rate of the dry mass conversion of oxygen by elemental analysis is 3.5 mass% or more and 7.0 mass% or less. More preferably, it is 4.0 mass% or more and 6.5 mass% or less.
  • the content in terms of dry mass of element A in platinum black is a content with the mass of platinum black not containing any water as a denominator, and is obtained from (Equation 9).
  • (Equation 9) Content (%) in terms of dry mass (mass of element A in platinum black / mass of platinum black when no moisture is contained) ⁇ 100
  • the moisture content of platinum black is calculated from the mass change before and after the vacuum drying treatment at 60 ° C. for 2 hours at a vacuum degree of 10 ⁇ 2 kPa or less.
  • the oxygen contained in the platinum black powder can take various forms such as atomic oxygen, adsorbed oxygen molecules, peroxides, oxygen radicals, nitrogen oxides, and the composition is an elemental analysis value of oxygen.
  • the oxygen content is analyzed by an oxygen / nitrogen analyzer such as TC-600 manufactured by LECO Japan.
  • the obtained platinum black powder has a primary particle size such that the platinum-containing species detected by powder X-ray diffraction is only cubic platinum, and the Pt (220) crystallite size is 3.0 nm or less. Is a small platinum black powder.
  • the platinum black powder obtained in this embodiment preferably has a dry mass equivalent content of chlorine and alkali metals contained as impurities of 500 ppm or less. Chlorine and alkali metals are analyzed with an ICP (High Frequency Inductively Coupled Plasma) emission spectrometer. In order to reduce chlorine and alkali metal contained as impurities, it is preferable to use an amine solution starting from crystals of hexahydroxoplatinic acid having a chlorine and alkali metal content as low as 500 ppm or less, respectively.
  • ICP High Frequency Inductively Coupled Plasma
  • the post-filter cake is obtained by washing with pure warm water having an electric conductivity of 0.8 ⁇ s / cm or less until the filtrate has an electric conductivity of 1.0 ⁇ s / cm or less.
  • the method for producing a platinum black colloid according to the present embodiment includes a nanocolloid production step of producing a hexahydroxoplatinic acid nanocolloid in a liquid phase, and a reducing agent added to the nanocolloid to form the nanocolloid.
  • a reduction step of reducing the colloid to form a platinum-containing colloid a washing step of filtering the platinum-containing colloid and washing with pure water, and a dispersion step of dispersing the washed platinum-containing colloid in a solvent.
  • the nanocolloid generation step, reduction step, and washing step are the same as in the method for producing platinum black powder according to this embodiment.
  • the platinum black wet cake after the washing step is placed in an appropriate solvent and dispersed with an ultrasonic wave or a planetary ball mill, etc., and in the particle size distribution measurement, a single peak is observed in the region of the particle diameter of 0.1 nm to 10,000 nm.
  • a platinum black colloid having a particle size distribution curve, an average particle size of 250 nm or less, and a polydispersity index of 0.15 or less and having a sharp particle size distribution is obtained.
  • a protic polar solvent composed of water, methanol, ethanol, n-propanol, isopropanol, or a mixture thereof is usually used, and preferably water.
  • the time for the dispersion treatment is usually 1 minute to 2 hours, preferably 5 minutes to 1 hour.
  • the concentration after dispersion is, for example, 0.01 g / L to 10.0 g / L of dry conversion platinum black, and preferably 0.10 g / L to 2.0 g / L.
  • the zeta potential of this colloid is measured, it is minus 40 mV or less, preferably minus 45 mV or less.
  • the higher the absolute value of the colloid zeta potential is 40 mV or higher, the higher the stability as a colloid.
  • the colloid of platinum black of the present invention is stable without agglomeration at room temperature in air for at least several days, preferably for a month, for example.
  • the platinum black powder is put into an appropriate solvent and dispersed by an ultrasonic wave or a planetary ball mill, thereby colloidalizing. May be.
  • the particle size distribution measurement has a single peak particle size distribution curve in the region of the particle diameter of 0.1 nm to 10000 nm, the average particle diameter is 250 nm or less, and the polydispersity index is 0.15 or less.
  • a colloid of platinum black having a sharp particle size distribution is obtained.
  • the type of the dispersion solvent, the dispersion treatment time, and the concentration after dispersion are the same as those described in the previous paragraph.
  • the method further includes an oxygen treatment step of blowing air or oxygen gas into the platinum-containing colloid after the reduction step. Two forms). This treatment increases the degree of dispersion of the platinum black colloidal particles.
  • the colloid of platinum black of the present invention includes, in addition to the solvent and platinum black, an ionomer of a perfluorosulfonic acid-based polymer electrolyte, for example, the trade name Nafion (manufactured by Deyupon), the trade name Flemion (manufactured by Asahi Glass), and the like. It may be added.
  • the ionomer may be added to a platinum black colloid after it has been prepared, or platinum black and ionomer may be added to a solvent and simultaneously dispersed to be colloidalized.
  • the addition ratio of the ionomer is, for example, in a mass ratio of 1: 0.01 to 1:10, preferably 1: 0.05 to 1: 2 with respect to platinum black 1.
  • Such an ionomer-added platinum black colloid is used as a catalyst ink for electrochemical electrode formation.
  • the pure water used in the examples was ultrapure water having a pH of 6.0 to 7.0 and an electric conductivity of 0.8 ⁇ s / cm or less, which was subjected to ion exchange twice.
  • the flask and Teflon (registered trademark) stirring blade used in the reaction were washed with aqua regia before use and then rinsed thoroughly with pure water before use.
  • An alkali metal was analyzed from a solution in which the crystals were dissolved in hydrochloric acid, and chlorine was analyzed from an filtrate obtained by dissolving platinum in an aqueous sulfuric acid solution and then removing platinum by aluminum reduction, using an ICP emission spectrometer (CIROS 120, manufactured by Rigaku Corporation).
  • the chlorine and Na contents in the hexahydroxoplatinic acid were 300 ppm and 450 ppm, respectively, with respect to platinum.
  • the concentration of alkali metals other than Na was below the detection limit of ICP analysis.
  • a hexahydroxoplatinic acid 2-aminoethanol aqueous solution was prepared as described in Example 1 of Patent Document 7 as follows.
  • Example 1 Production of high specific surface area platinum black (production method through oxygen treatment step) (Nano colloid production process) 1.2 L of pure water was placed in a 3 L four-necked flask, and 1.50 g of glacial acetic acid in 20 ml of pure water was added thereto. A Teflon (registered trademark) stirring rod with a Teflon (registered trademark) blade was connected to a motor, and the mixture was sufficiently stirred by rotating at a liquid temperature of 25 ° C. and 320 rpm. The inside of the flask was purged with synthetic air (zero air).
  • colloid average particle diameter Z-Average 110 nm, polydispersity index PDI 0.110 is obtained. Obtained and confirmed the formation of hexahydroxoplatinic acid nanocolloids.
  • the hexahydroxoplatinic acid nanocolloid was heated with a mantle heater while stirring under air flow, and the temperature was raised to 95 ° C. in 40 minutes. At 95 ° C., 0.92 ml of 25% pure aqueous solution of 98% formic acid was slowly dropped from the dropping funnel at a constant dropping rate over 40 minutes. Even after completion of the dropping, stirring was maintained at a liquid temperature of 95 ° C. for 40 minutes.
  • the color of the colloid changed to gray 30 minutes after the start of dropping, and changed to dark black several minutes later.
  • stirring was maintained at a liquid temperature of 95 ° C. for about 10 minutes, and then the heating was stopped and the mixture was cooled to room temperature while stirring.
  • Oxygen treatment process When the liquid temperature was cooled to 30 ° C., the colloid was stirred while blowing synthetic air from the side tube at a flow rate of 300 mL / min, and held for 30 minutes.
  • the dry-converted oxygen content in the platinum black was analyzed to be 5.6% by mass using an oxygen / nitrogen analyzer (manufactured by LECO Japan, TC-600). According to ICP analysis, the dry conversion contents of chlorine and Na were 250 ppm and 200 ppm, respectively. The content of alkali metals other than Na was below the lower limit of detection by ICP analysis.
  • Example 2 Production of platinum black colloid 0.10 g of platinum black obtained in Example 1 was added to 50 ml of pure water and subjected to ultrasonic dispersion treatment for 15 minutes to obtain a black colloid.
  • the particle size of the colloidal particles was measured with a dynamic light scattering particle size distribution meter, the average particle size was Z-Average 195 nm and the polydispersity index PDI was 0.15.
  • the zeta potential of this colloid was measured with a zeta potential measuring device (manufactured by Malvern, Zeta Sizer Nano) and found to be minus 47 mV.
  • Example 3 Production of high specific surface area platinum black (production method without passing through oxygen treatment step) (Nano colloid production process) Add 0.75 g of glacial acetic acid in 10 ml of pure water to 1.2 L of pure water, and add dropwise dropwise dilute 7.5 ml of pure water in 8.83 g of hexahydroxoplatinic acid 2-ethanolamine containing 0.75 g of platinum. Except that, milky white hexahydroxoplatinic acid nanocolloid was obtained in the same manner as in the nanocolloid production step of Example 1.
  • the colloid turned dark black 20 minutes after the dropping. In addition, after hold
  • the obtained black slurry was treated in the same manner as in the washing step and the drying step of Example 1 to obtain 0.75 g of platinum black powder.
  • the specific surface area after the pretreatment was measured in the same manner as in Example 1 to obtain a BET specific surface area of 82 m 2 / g and a total pore volume of 0.041 cm 3 / g.
  • the powder method X-ray diffraction showed that the diffraction angle of fcc platinum (111) was 2 ⁇ 38.9 ° and the (220) crystallite diameter was 2.2 nm.
  • the oxygen content in platinum black was 4.6%, and the chlorine and Na contents were 270 ppm and 200 ppm, respectively.
  • the content of alkali metals other than Na was below the lower limit of detection by ICP analysis.
  • Example 4 Production of high specific surface area platinum black (production method through an oxygen treatment step) (Nano colloid production process)
  • a milky white nanocolloid of hexahydroxoplatinic acid containing 1.50 g of platinum was obtained.
  • the colloid was heated with a mantle heater while stirring under a synthetic air flow, and the temperature was raised to 90 ° C. in 40 minutes.
  • 0.92 ml of 25% pure aqueous solution of 98% formic acid was dropped from the dropping funnel over 40 minutes at a constant dropping rate. Even after completion of the dropping, stirring was maintained at a liquid temperature of 90 ° C. for 3 hours.
  • Example 1 Production of Conventional Platinum Black According to the production method of Example 1 described in Patent Document 1, treatment was performed as follows. 2.34 g of hexahydroxoplatinic acid white crystals corresponding to 1.50 g of platinum were dissolved in 27.6 g of a 31.4 mass% nitric acid aqueous solution. Put the hexahydroxoplatinic acid aqueous solution of hexahydroxoplatinic acid into a 500 ml four-necked flask, and stir it well with a Teflon (registered trademark) stirring blade, and slowly add 126 ml of pure water from the dropping funnel of the side tube over 1 hour. It was dripped.
  • Teflon registered trademark
  • the mixture was stirred and held for 30 minutes, then heated with a mantle heater, heated to 70 ° C. over 2 hours, and stirred and held at 70 ° C. for 1 hour to obtain an orange suspension.
  • 12 ml of concentrated aqueous ammonia was added dropwise to neutralize the suspension until the pH of the suspension was 5.0.
  • 1.50 ml of formic acid was added at a constant rate over 1 hour using a microfeeder.
  • the color of the suspension changed from orange to black.
  • the stirring was kept for 1 hour, and then allowed to cool to room temperature, and the precipitated platinum black was filtered.
  • the filtrate was washed with pure water until the conductivity was 2.0 ⁇ s / cm or less, air-dried, and dried at 120 ° C. Similarly to measure the surface area as in Example 1 to obtain a specific surface area of 53m 2 / g, a total pore volume of 0.025 cm 3 / g.
  • the powder method X-ray diffraction of this platinum black showed that the (220) crystallite diameter of fcc platinum was 5.1 nm.
  • the platinum black powder and the platinum black colloid according to the present invention are, for example, a fin chemical hydrogenation catalyst or oxidation catalyst, or a gas diffusion electrode catalyst for use in fuel cells, electrolysis cells and electrochemical sensors. Available as

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Abstract

L'invention porte sur une poudre de catalyseur de noir de platine hautement active. La poudre de noir de platine a une surface spécifique BET de 80 m²/g ou plus, ou même de 90 m²/g ou plus. La poudre de noir de platine est produite comme suit : un nanocolloïde d'acide hexahydroxoplatinique est produit dans une phase liquide ; le nanocolloïde est réduit par ajout d'un agent réducteur à celui-ci, de telle sorte qu'un colloïde contenant du platine est formé ; le colloïde contenant du platine est filtré, et nettoyé avec de l'eau purifiée ; et le colloïde contenant du platine nettoyé est séché.
PCT/JP2009/071740 2009-01-13 2009-12-28 Poudre de noir de platine, colloïde de noir de platine, procédé de production de poudre de noir de platine, et procédé pour la production de colloïde de noir de platine WO2010082443A1 (fr)

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CN104416164A (zh) * 2013-09-04 2015-03-18 中国科学院苏州纳米技术与纳米仿生研究所 铂黑及其制备方法
WO2019064931A1 (fr) * 2017-09-29 2019-04-04 日立Ｇｅニュークリア・エナジー株式会社 Solution colloïdale d'oxyde de platine, méthode de production de solution colloïdale d'oxyde de platine et dispositif d'injection de solution colloïdale d'oxyde de platine
CN111745164A (zh) * 2020-07-14 2020-10-09 昆明理工大学 一种超细球状铂粉的制备方法
CN113681023A (zh) * 2021-08-18 2021-11-23 中国科学院城市环境研究所 一种规则形貌纳米铂黑及其制备方法与应用
WO2024042610A1 (fr) * 2022-08-23 2024-02-29 株式会社Ｃｅｐプロジェクト Procédé de production d'une solution de nanoparticules de platine, agent antibactérien et produit antibactérien

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CN104416164A (zh) * 2013-09-04 2015-03-18 中国科学院苏州纳米技术与纳米仿生研究所 铂黑及其制备方法
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WO2019064931A1 (fr) * 2017-09-29 2019-04-04 日立Ｇｅニュークリア・エナジー株式会社 Solution colloïdale d'oxyde de platine, méthode de production de solution colloïdale d'oxyde de platine et dispositif d'injection de solution colloïdale d'oxyde de platine
CN111745164A (zh) * 2020-07-14 2020-10-09 昆明理工大学 一种超细球状铂粉的制备方法
CN111745164B (zh) * 2020-07-14 2022-12-23 昆明理工大学 一种超细球状铂粉的制备方法
CN113681023A (zh) * 2021-08-18 2021-11-23 中国科学院城市环境研究所 一种规则形貌纳米铂黑及其制备方法与应用
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WO2024042610A1 (fr) * 2022-08-23 2024-02-29 株式会社Ｃｅｐプロジェクト Procédé de production d'une solution de nanoparticules de platine, agent antibactérien et produit antibactérien

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