WO2015050106A1 - Paper-like catalyst structure and method for manufacturing same - Google Patents

Paper-like catalyst structure and method for manufacturing same Download PDF

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Publication number
WO2015050106A1
WO2015050106A1 PCT/JP2014/076027 JP2014076027W WO2015050106A1 WO 2015050106 A1 WO2015050106 A1 WO 2015050106A1 JP 2014076027 W JP2014076027 W JP 2014076027W WO 2015050106 A1 WO2015050106 A1 WO 2015050106A1
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paper
catalyst structure
aluminum
catalyst
nickel
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PCT/JP2014/076027
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French (fr)
Japanese (ja)
Inventor
康男 柿原
真司 高橋
祐介 白鳥
美緒 坂本
卓也 北岡
一成 佐々木
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戸田工業株式会社
国立大学法人九州大学
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Priority to JP2015540499A priority Critical patent/JPWO2015050106A1/en
Publication of WO2015050106A1 publication Critical patent/WO2015050106A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
    • C01B3/40—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts characterised by the catalyst
    • 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
    • H01M4/88—Processes of manufacture
    • H01M4/8875—Methods for shaping the electrode into free-standing bodies, like sheets, films or grids, e.g. moulding, hot-pressing, casting without support, extrusion without support
    • 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
    • H01M4/88—Processes of manufacture
    • H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
    • H01M4/8882—Heat treatment, e.g. drying, baking
    • H01M4/8885—Sintering or firing
    • 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
    • H01M4/9041—Metals or alloys
    • H01M4/905—Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0227—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step
    • C01B2203/0233—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being a steam reforming step
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/10—Catalysts for performing the hydrogen forming reactions
    • C01B2203/1005—Arrangement or shape of catalyst
    • C01B2203/1011—Packed bed of catalytic structures, e.g. particles, packing elements
    • C01B2203/1017—Packed bed of catalytic structures, e.g. particles, packing elements characterised by the form of the structure
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/10—Catalysts for performing the hydrogen forming reactions
    • C01B2203/1041—Composition of the catalyst
    • C01B2203/1047—Group VIII metal catalysts
    • C01B2203/1052—Nickel or cobalt catalysts
    • C01B2203/1058—Nickel catalysts
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/10—Catalysts for performing the hydrogen forming reactions
    • C01B2203/1041—Composition of the catalyst
    • C01B2203/1082—Composition of support materials
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/12—Feeding the process for making hydrogen or synthesis gas
    • C01B2203/1205—Composition of the feed
    • C01B2203/1211—Organic compounds or organic mixtures used in the process for making hydrogen or synthesis gas
    • C01B2203/1235—Hydrocarbons
    • C01B2203/1241—Natural gas or methane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M2008/1293—Fuel cells with solid oxide electrolytes
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • the present invention relates to a paper-like catalyst structure for efficiently producing hydrogen from a gas containing hydrocarbon and a method for producing the same.
  • a catalyst used in the reforming reaction a catalyst is used in which ruthenium or cheaper nickel is supported on a carrier mainly composed of alumina and the catalyst is further shaped into a pellet.
  • Patent Documents 1 and 2 Also proposed are powders of complex metal oxides containing magnesium and aluminum carrying inexpensive nickel fine particles, and reforming catalysts in which the powders are formed into pellets.
  • Patent Documents 3 and 4 As a catalyst molded body, a paper-like catalyst structure molded into a sheet shape different from the pellet-shaped structure and the conventional honeycomb structure has been proposed (Patent Documents 3 and 4).
  • the paper-like catalyst structure can be easily obtained by a wet papermaking method. Furthermore, it is considered that the reaction of the reaction gas can proceed efficiently by the unique fiber network structure possessed by the paper-like catalyst structure and the metal catalyst supported on the fiber network. Further, there is an advantage that the reactivity can be controlled by stacking a plurality of types of paper-like catalyst structures together with high shape processability. Furthermore, a configuration in which a paper-like catalyst structure is arranged in front of the fuel electrode of a solid oxide fuel cell has also been proposed (Patent Document 5).
  • Biogas which is a mixed gas of methane gas and carbon dioxide gas, is generated from domestic wastewater and wastewater from the livestock industry by methane fermentation.
  • it is better to convert the biogas directly into hydrogen and carbon monoxide by dry reforming and to generate electricity with a solid oxide fuel cell.
  • no catalyst structure having sufficient reforming performance has been reported so far.
  • the carbon component deposited in the catalyst is always a problem when reforming hydrocarbons containing methane gas.
  • the carbon component When the carbon component is deposited on the metal serving as the reforming catalyst to deteriorate the reforming performance, the carbon component causes problems such as blocking the gas diffusion flow path in the porous catalyst structure. In order to maintain the reforming performance for a long time, it is necessary to suppress carbon precipitation.
  • a noble metal such as ruthenium with relatively little carbon deposition is used as a reforming catalyst, but ruthenium metal is generally an expensive material. Therefore, various inexpensive catalysts using nickel metal have been studied, but dry reforming of biogas is possible, but it is difficult to suppress carbon deposition.
  • Patent Document 4 a paper-like catalyst structure for steam reforming a gas mainly composed of methane such as city gas has been proposed (Patent Document 4).
  • Patent Document 4 requires firing at 1000 ° C. or higher in order to improve the gas reforming ability of a paper catalyst in which a nickel metal catalyst is held by an inorganic binder.
  • the nickel metal particles acting as a catalyst will sinter and become coarser, and the catalytic ability will deteriorate, and the general heat-resistant fiber constituting the paper-like catalyst structure will increase the crystallinity. Therefore, there is a concern about deterioration of mechanical strength.
  • Non-patent Document 1 As a catalyst for carbon dioxide reforming (dry reforming) of methane gas, a composite metal oxide powder of magnesium and aluminum produced from hydrotalcite and containing nickel fine particles has been proposed (Non-patent Document 1).
  • the catalyst is considered to be very effective as a catalyst that has high reforming characteristics and suppresses carbon deposition.
  • it is considered desirable to form a paper-like catalyst structure as shown in the present invention rather than as a catalyst powder. There has been no evaluation of reformability when a method or dry reforming is performed.
  • carbon deposition may be observed after the biogas reforming test, and it is necessary to improve the composition and manufacturing method of the paper-like catalyst structure in order to maintain stable reforming for a longer time. there were.
  • an object of the present invention is to provide a paper-like catalyst structure for efficiently producing hydrogen.
  • the present invention provides a paper-like catalyst structure capable of performing the reforming reaction at a low temperature in order to efficiently produce hydrogen during biogas dry reforming. Further, the present invention provides a paper-like catalyst structure having a high carbon deposition resistance during dry reforming of biogas.
  • the present invention is a paper-like catalyst structure (catalyst sheet) comprising inorganic fibers and a composite metal oxide containing magnesium and aluminum on which nickel metal fine particles having an average particle diameter of 1 to 20 nm are supported (the present invention). 1).
  • the present invention is a paper-like catalyst structure (catalyst sheet) according to the first aspect of the present invention, wherein the inorganic fiber is a fiber containing at least one selected from alumina, silica, zirconia, and ceria (Invention 2).
  • the present invention is the paper-like catalyst structure (catalyst sheet) according to the first or second aspect of the present invention, wherein the inorganic fibers include low crystalline fibers (Invention 3).
  • the present invention provides a sheet-like formed body by a wet papermaking method using a slurry containing inorganic fibers, an inorganic binder, and layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum,
  • the molded body is fired at a temperature of 500 ° C. or more and 950 ° C. or less, immersed in an aqueous solution in which a nickel compound is dissolved, dried, and then heated and reduced at a temperature of 700 ° C. or more and 950 ° C. or less.
  • a method for producing a paper-like catalyst structure (catalyst sheet) according to any one of 3 (present invention 4).
  • the present invention provides a slurry containing inorganic fibers, inorganic binders and layered double hydroxide particles containing magnesium, aluminum and nickel or composite metal oxide particles containing magnesium, aluminum and nickel by a wet papermaking method.
  • Is a method for producing a catalyst structure (catalyst sheet) (Invention 5).
  • the present invention provides the paper-like catalyst according to the present invention 4 or 5 using layered double hydroxide particles or composite metal oxide particles having a BET specific surface area of 100 m 2 / g or less after calcination at 600 ° C. for 5 hours. It is a manufacturing method of a structure (catalyst sheet) (Invention 6).
  • the paper-like catalyst structure of the present invention carries fine particles of nickel metal and can efficiently produce hydrogen from a hydrocarbon-containing gas such as methane.
  • a hydrocarbon-containing gas such as methane.
  • high reforming characteristics are provided, so that hydrogen can be efficiently produced even in dry reforming of biogas which is a mixed gas of methane gas and carbon dioxide gas.
  • the paper-like catalyst structure of the present invention can improve the carbon precipitation resistance by the composite metal oxide particles contained in the catalyst structure, so that there is no blockage of the gas diffusion region in the catalyst structure. A stable reforming reaction for a long time can be maintained.
  • a paper-like catalyst structure that can easily carry fine nickel metal particles on the paper-like catalyst structure and can efficiently produce hydrogen.
  • a catalyst structure can be produced.
  • the paper-like catalyst structure according to the present invention includes inorganic fibers and a composite metal oxide containing magnesium and aluminum on which nickel metal fine particles having an average particle diameter of 20 nm or less are supported.
  • the “paper” is a catalyst sheet or a catalyst inorganic fiber sheet in which the catalyst structure of the present invention contains the above-mentioned components, and is obtained by a method of producing paper using a paper making apparatus or the like using inorganic fibers as constituent components It means having properties as an aggregate of inorganic fibers such as paper. Therefore, it is described as “paper” for convenience.
  • the thickness of the paper-like catalyst structure (catalyst sheet) according to the present invention is usually 0.5 to 3 mm, although it depends on the type of inorganic fiber used and the type and amount of oxide particles to be formed. When the thickness exceeds 3 mm, the shape workability deteriorates, and when the thickness is less than 0.5 mm, the strength as the catalyst structure is insufficient.
  • the inorganic fiber constituting the paper-like catalyst structure a fiber body made of an inorganic substance having high thermal stability and chemical stability under the use conditions of the paper-like catalyst structure of the present invention can be used.
  • inorganic substances include metal oxides, metal carbides, and metal nitrides, and are usually metal oxides.
  • the fiber body made of such an inorganic material include alumina and fiber bodies mainly composed of alumina and silica.
  • the paper-like catalyst structure according to the present invention may use ion conductive oxide fibers in combination as part of the inorganic fibers.
  • an ion conductive oxide in combination, it acts as a promoter for suppressing carbon deposition.
  • ion conductive oxides include zirconia (ZrO 2 ) -based oxides and ceria (CeO 2 ) -based oxides, and the ion-conductive oxide is particularly high because of its high chemical stability in a high-temperature reducing atmosphere. It is preferable that a stabilized zirconia fiber is included as a physical fiber.
  • yttria stabilized zirconia YSZ
  • ScSZ scandia stabilized zirconia
  • CaSZ calcia stabilized zirconia
  • YSZ yttria-stabilized zirconia
  • the inorganic fiber constituting the paper-like catalyst structure includes a low crystalline fiber.
  • the paper-like catalyst structure has high mechanical strength and toughness.
  • the low crystalline fiber for example, an amorphous refractory ceramic fiber (for example, IBI WOOL (registered trademark) manufactured by Ibiden Co., Ltd., isowool manufactured by Isolite Industrial Co., Ltd.) is a fiber body mainly composed of alumina and silica. (Registered trademark)) or low crystalline alumina fiber (for example, Denka Arsen (registered trademark) B80L manufactured by Denki Kagaku Kogyo Co., Ltd.) is preferable.
  • the low crystallinity of an inorganic fiber is maintained, without passing through the high temperature exceeding 950 degreeC.
  • the low crystalline fiber is preferably 30% or more of the inorganic fibers constituting the paper-like catalyst structure.
  • the inorganic fibers constituting the paper-like catalyst structure are bound by the inorganic binder component.
  • the ratio of the composition ratio of magnesium and aluminum is preferably 3: 1 to 1.5: 1.
  • the composite metal oxide containing magnesium and aluminum contained in the paper-like catalyst structure according to the present invention carries nickel metal fine particles having an average particle diameter of 1 to 20 nm. It is difficult to make the average particle diameter of metallic nickel supported on the composite metal oxide less than 1 nm. When the average particle diameter of the nickel metal fine particles exceeds 20 nm, the initial activity of the catalyst is lowered and the carbon deposition resistance is deteriorated.
  • the average particle diameter of the nickel metal fine particles is preferably 1 to 18 nm, more preferably 2 to 15 nm.
  • the particle diameter of the nickel metal fine particles is observed with a scanning transmission electron microscope (STEM), and can be measured from the nickel metal fine particles present on the composite metal oxide containing magnesium and aluminum.
  • STEM scanning transmission electron microscope
  • the amount of nickel contained in the paper-like catalyst structure is appropriately selected according to the use of the paper-like catalyst structure, the composition of the raw material gas, etc., but usually when the entire paper-like catalyst structure is 100% by weight And in the range of 1 to 20% by weight in terms of nickel element.
  • the paper-like catalyst structure according to the present invention preferably has a BET specific surface area of 5 m 2 / g or more. If the BET specific surface area is smaller than 5 m 2 / g, the contact area between the hydrocarbon-containing gas and the nickel fine particles becomes small, resulting in a poor conversion rate.
  • the BET specific surface area is more preferably 6 m 2 / g or more, and even more preferably 6 to 20 m 2 / g.
  • the BET specific surface area is adjusted by the type and amount of layered double hydroxide particles containing magnesium, aluminum and nickel or composite metal oxide particles containing magnesium, aluminum and nickel incorporated into the paper-like catalyst structure. .
  • the strength of the paper-like catalyst structure according to the present invention can be measured by, for example, the maximum load until the test piece is torn when the test piece is held and pulled as shown in FIG.
  • the maximum load until the test piece is torn is preferably 1.0 (N) or more. When the maximum load is less than 1.0 (N), handling is not easy because the paper-like catalyst structure is brittle.
  • the paper-like catalyst structure according to the present invention is a sheet formed by wet papermaking using a slurry containing inorganic fibers, an inorganic binder, and layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum. It can be produced by forming a shaped molded body, dipping the molded body in an aqueous solution in which a nickel compound is dissolved, drying, firing, and heat reduction.
  • inorganic fiber, inorganic binder and layered double hydroxide particles containing magnesium and aluminum, or composite metal oxide particles containing magnesium and aluminum, and other components as necessary (porosity adjusting agent, dispersant, etc.) )
  • solvent to prepare a slurry dispersed until uniform.
  • Water, alcohols, and water-soluble ketones can be used as the slurry solvent.
  • the inorganic fiber various fiber bodies made of an inorganic material having high thermal stability and chemical stability under the use conditions of the paper-like catalyst structure of the present invention can be used.
  • the length and thickness of the inorganic fiber may be within a range in which a paper-like catalyst structure can be formed, and is appropriately determined in consideration of the use of the paper-like catalyst structure of the present invention.
  • the average total length is 30 ⁇ m to 6 mm, preferably 50 ⁇ m to 3 mm
  • the average diameter is 1 to 20 ⁇ m, preferably 4 to 10 ⁇ m
  • the minimum fiber diameter is 3.0 ⁇ m or more.
  • the length and thickness of inorganic fiber can be confirmed with a scanning electron microscope (SEM).
  • inorganic binder component conventionally known as long as it has sufficient chemical stability under the conditions of use of the paper-like catalyst structure of the present invention and can bind inorganic fibers to sufficient mechanical strength.
  • Inorganic binders can be used.
  • commercially available alumina sol, zirconia sol, or ceria sol can be used. Considering the effect of suppressing carbon deposition, zirconia sol or ceria sol is more preferable.
  • the amount of the inorganic binder in the slurry is preferably 1 to 70 parts by weight as the solid content of the inorganic binder with respect to 100 parts by weight of the inorganic fibers.
  • the precursor of the composite metal oxide containing magnesium and aluminum contained in the paper-like catalyst structure is preferably a hydrotalcite-like compound.
  • layered double hydroxide particles containing magnesium and aluminum which are hydrotalcite-like compounds, or a composite containing magnesium and aluminum from which interlayer water of hydrotalcite-like compounds has been released. It is preferred to add a metal oxide to the solvent.
  • the hydrotalcite-like compound is dehydrated and decarboxylated from the structure by heating to become a composite metal oxide, but afterwards it is known that the layered structure of the hydrotalcite-like compound is regenerated by immersion in an aqueous solution. It has been. At this time, by immersing in an aqueous solution in which nickel ions are dissolved, a part of magnesium ions is replaced with nickel ions while the layered structure is regenerated. Thereafter, it is known that nickel ions become fine metal particles when heated and reduced. Alternatively, it is known that nickel metal fine particles are precipitated by mixing a nickel ion in place of a part of magnesium ion to prepare a hydrotalcite-like compound, followed by heat reduction (Non-patent Document 2). ).
  • the layered double hydroxide particles containing magnesium and aluminum added to the slurry or the composite metal oxide particles containing magnesium and aluminum preferably have an average particle size of preferably 50 to 500 nm, more preferably 70. ⁇ 150 nm.
  • the ratio of the composition ratio of magnesium to aluminum in the layered double hydroxide containing magnesium and aluminum added to the slurry or the composite metal oxide containing magnesium and aluminum should be 3: 1 to 1.5: 1. preferable.
  • the layered double hydroxide particles containing magnesium and aluminum used in the present invention or the composite metal oxide particles containing magnesium and aluminum have a BET specific surface area of 100 m 2 / g after being heated and fired at a temperature of 600 ° C. It is preferable not to exceed the carbon deposition resistance.
  • the BET specific surface area can be adjusted to the above range by adjusting the particle size and composition ratio of the layered double hydroxide particles containing magnesium and aluminum, or the composite metal oxide particles containing magnesium and aluminum. . Note that the layered double hydroxide containing magnesium and aluminum added to the slurry, or the composite metal oxide containing magnesium and aluminum does not have to be heated and fired at 600 ° C.
  • a layered double hydroxide containing magnesium and aluminum or a composite metal oxide containing magnesium and aluminum having a BET specific surface area of greater than 100 m 2 / g under heating conditions of 600 ° C. is heated and fired to produce a paper-like catalyst structure During the process, it strongly interacts with the inorganic binder present at around 500 to 600 ° C., thereby inhibiting the melting and particle growth of the inorganic binder. Therefore, a fine inorganic binder exists in the paper-like catalyst structure. This fine inorganic binder remains in the paper-like catalyst structure. It is believed that thermal decomposition of the methane component in the biogas occurs remarkably on this fine inorganic binder, and as a result, carbon is deposited.
  • a layered double hydroxide containing magnesium and aluminum having a BET specific surface area of less than 100 m 2 / g under a heating condition of 600 ° C. or a composite metal oxide containing magnesium and aluminum has a small interaction with an inorganic binder. Or almost no melting and particle growth between the inorganic binders during the heating and baking process for producing the paper-like catalyst structure, and the thermal decomposition reaction of methane hardly occurs, and as a result, it does not cause carbon precipitation. Yes.
  • the amount of the layered double hydroxide particles containing magnesium and aluminum or the composite metal oxide particles containing magnesium and aluminum in the slurry is preferably 1 part by weight to 70 parts by weight with respect to 100 parts by weight of the inorganic fibers. .
  • the layered double hydroxide particles containing magnesium and aluminum, or the composite metal oxide particles containing magnesium and aluminum contain a metal or metal oxide such as nickel or ruthenium in advance when the slurry is prepared. May be.
  • the layered double hydroxide particles containing magnesium and aluminum or the composite metal oxide particles containing magnesium and aluminum are dispersed as necessary in order to disperse them uniformly in the paper-like catalyst structure. It may be dispersed in advance. Further, a dispersant or the like may be added.
  • the pulp ensures the strength in the wet state after paper making, and facilitates the collection of the sheet-like molded body before firing from the mesh for filtration. Further, since the pulp is burned off during the firing of the sheet-like molded body and voids (diffusion paths) are generated, the pores inside the paper-like catalyst structure can be adjusted.
  • the amount of the pulp is 1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the inorganic fibers. It is preferable to use a pulp that has been beaten in advance.
  • a floc is formed by adding a flocculant such as an ionic polymer to the slurry, and the floc is collapsed by applying a hydraulic shear force.
  • a sheet-like composite is obtained.
  • the obtained sheet-like composite is dried and subjected to heat treatment and pressure treatment to obtain a sheet-like molded article having a uniform thickness.
  • the sheet-like molded body is fired in a temperature range of 500 ° C. or more and 950 ° C. or less (first firing).
  • Air, inert gas (nitrogen gas, argon gas, etc.), etc. are used for the baking atmosphere at the time of baking, but air is usually used.
  • the composite metal oxide containing magnesium and aluminum is bound to the inorganic fiber and the inorganic fibers are bonded together. Do the binding.
  • the firing temperature is preferably 700 ° C. to 950 ° C., more preferably 800 ° C. to 900 ° C.
  • a spinel structure starts to grow by heating at about 1000 ° C.
  • a compound having a spinel structure is difficult to regenerate into a hydrotalcite-like compound even when immersed in an aqueous solution, and at the same time, it is difficult for substitution of magnesium ions and nickel ions to occur. It becomes difficult to obtain. Therefore, it is preferable to perform firing in a temperature range in which a spinel structure compound is not generated or is slightly generated.
  • the firing temperature is higher than 950 ° C.
  • the crystallization of inorganic fibers proceeds excessively, and the mechanical strength of the paper-like catalyst body is lowered, which is not preferable.
  • the fired sheet-like molded body is dipped in an aqueous solution in which a nickel compound is dissolved and dried to incorporate a composite metal oxide containing nickel, whereby a fired sheet-like molded body can be obtained.
  • a nickel compound nitrates, sulfates, carbonates, acetates, halides, ammonium salts, oxalates and the like may be selected as appropriate.
  • the concentration of nickel in the aqueous nickel compound solution is preferably 0.1 mol / L to 1 mol / L.
  • the sheet-shaped molded body may be washed with water after the sheet-shaped molded body is immersed in an aqueous solution in which a nickel compound is dissolved.
  • a nickel compound By washing with water, the nickel compound adhering to the surface of the sheet-like molded body can be washed away, and nickel can be supported only on the precursor of the composite metal oxide containing magnesium and aluminum.
  • Excess nickel component deposited on the inorganic fiber or inorganic binder can cause carbon deposition depending on the conditions during the reforming reaction. Therefore, excess nickel components can be removed by washing or the like according to the reforming conditions.
  • the sheet-like molded body dipped in an aqueous solution in which a nickel compound is dissolved and dried may be further fired at 600 ° C. or more and 950 ° C. or less (second firing).
  • Air, inert gas (nitrogen gas, argon gas, etc.), etc. are used for the baking atmosphere at the time of baking, but air is usually used.
  • the anion components (nitrate ions, carbonate ions, halogen ions, etc.) of the nickel compounds adhering to the surface of the sheet-like molded body can be decomposed and removed, and during the subsequent reduction, nickel fine particles are formed Can be prevented.
  • the layered double hydroxide particles containing magnesium and aluminum or the composite metal oxide particles containing magnesium and aluminum incorporated into the sheet-shaped molded body contain nickel metal or metal oxide in advance
  • the sheet-shaped molded body may be fired only once to obtain a fired sheet-shaped molded body.
  • the sheet-shaped molded body is in an aqueous solution in which the nickel compound is dissolved after the first firing. It is possible to obtain a sheet-like molded body that is immersed in the substrate, contains a large amount of nickel in the precursor of the composite metal oxide containing magnesium and aluminum, and further baked by second baking.
  • the fired sheet-like molded body is heated and reduced at 700 ° C. or more and 950 ° C. or less.
  • the atmosphere during the reduction is not particularly limited as long as it is a reducing atmosphere such as a gas containing hydrogen.
  • a paper-like catalyst structure including a composite metal oxide containing magnesium and aluminum on which nickel fine particles having a particle diameter of 20 nm or less are supported can be obtained.
  • Heat reduction at a temperature higher than 950 ° C. is not preferable because the particle size of the nickel particles increases, the BET specific surface area decreases, and the gas reforming efficiency decreases.
  • the heating reduction temperature is preferably 800 ° C. to 950 ° C.
  • the heating reduction temperature is higher than 950 ° C.
  • the crystallization of inorganic fibers proceeds excessively and the mechanical strength of the paper-like catalyst body is lowered, which is not preferable.
  • the present inventors have found that hydrotalcite-like It has been found that when the compound is a nickel carrier, high catalytic properties are exhibited by heat treatment at 950 ° C. or lower.
  • the methane conversion rate in the reforming tests described in the examples is usually 50% or more, preferably 60% or more.
  • the paper-like catalyst structure is obtained by immersing the hydrotalcite-like compound present in the paper-like catalyst structure bound by an inorganic binder in an aqueous solution containing nickel ions and then heating and reducing it at 950 ° C. or lower.
  • Nickel contained in the body is preferentially produced as ultrafine particles of nickel metal having an average particle diameter of 1 to 20 nm on a composite metal oxide containing magnesium and aluminum, and reforming reaction at a low temperature of 800 ° C. or lower.
  • the present inventors have found that a high conversion rate can be obtained during dry reforming of biogas.
  • the inventors of the present invention have a layered double hydroxide or magnesium and aluminum containing magnesium and aluminum as precursors of a composite metal oxide containing magnesium and aluminum on which nickel as a catalyst is supported.
  • the composite metal oxide containing methane the methane conversion rate of biogas and the carbon deposition resistance
  • it contains magnesium and aluminum having a BET specific surface area of not more than 100 m 2 / g after firing at 600 ° C.
  • an aqueous solution containing nickel ions for layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum present in a paper-like catalyst structure bound by an inorganic binder
  • the nickel contained in the paper-like catalyst structure is preferentially nickel having an average particle diameter of 1 to 20 nm on the composite metal oxide containing magnesium and aluminum by being heated and reduced at 950 ° C. or lower after being immersed therein. It has been found that a high methane conversion rate can be obtained at the time of biogas reforming even in a reforming reaction produced as ultrafine metal particles at a low temperature of 800 ° C. or lower.
  • the length and thickness of the inorganic fibers were confirmed with a scanning electron microscope (SEM) (HITACHI S-4800 type).
  • the average particle diameter of the layered double hydroxide particles containing magnesium and aluminum added to the slurry, or the composite metal oxide particles containing magnesium and aluminum confirmed.
  • the BET specific surface area of the layered double hydroxide containing magnesium and aluminum or the composite metal oxide containing magnesium and aluminum was indicated by a value measured using (BELSOPE-mini II manufactured by Nippon Bell). The BET specific surface area was measured for those dried in air at 105 ° C. for 3 hours and cooled to room temperature, and those fired in air at 600 ° C. for 5 hours and cooled to room temperature.
  • the ratio of magnesium to aluminum contained in the layered double hydroxide containing magnesium and aluminum or the composite metal oxide containing magnesium and aluminum was measured using an ICP plasma emission spectrometer (iCAP-6500DUO manufactured by Thermo Fisher). It was shown by the value.
  • the average particle diameter of the nickel metal fine particles was observed by a scanning transmission electron microscope (STEM) (HD-2300A manufactured by HITACHI) after roughly pulverizing the paper-like catalyst structure, and a composite metal oxide containing magnesium and aluminum It calculated as an average value of 50 nickel metal fine particles existing above.
  • STEM scanning transmission electron microscope
  • the amount of nickel contained in the paper-like catalyst structure is measured by preparing a measurement sample by pulverizing the pulverized paper-like catalyst structure using lithium tetraborate, an ICP plasma emission spectrometer (iCAP-6500DUO manufactured by Thermo Fisher). It showed by the value measured using.
  • the BET specific surface area of the paper-like catalyst structure was indicated by a value measured using (BELSOPE-mini II, manufactured by Nippon Bell).
  • the strength of the paper-like catalyst structure is obtained by chucking a test piece obtained by cutting the paper-like catalyst structure into a strip of 50 mm ⁇ 15 mm with a gripping portion having a width of 5 mm at intervals of 30 mm. The maximum load until the specimen was torn and was pulled with an IMADA tensile tester at a pulling rate of 100 mm / min.
  • Used raw materials Inorganic fiber / Amorphous silica-alumina fiber IBI WOOL (registered trademark) J-15, manufactured by Ibiden Co., Ltd.) Average fiber diameter: 2.3 ⁇ m Average fiber length: 38 ⁇ m 2.
  • Oxide sol (inorganic binder) ⁇ Zirconia sol (manufactured by Daiichi rare element chemical industry) ⁇ Ceria sol (Daiichi Rare Element Chemical Industries) ⁇ Yttria stabilized zirconia sol (manufactured by Nissan Chemical Industries, Ltd.) 3. All of the ionic polymers were prepared in 0.2 wt% aqueous solutions.
  • PDADMAC manufactured by polydyldimethylammonium chloride, Sigma-Aldrich, Ltd.
  • Cationic molecular weight about 3 ⁇ 10 5 Charge density: 5.5 meq / g ⁇ Polyacrylamide (Fujikamizu Co., Ltd.)
  • Anionic molecular weight about 1.2 ⁇ 10 7 Charge density: 0.83-1.36 meq / g
  • Example 1 As inorganic fibers, IBI WOOL J-15 (5 g) and 600 mL of distilled water were mixed with a mixer for about 3 minutes. Next, a magnetic stirrer chip, 1 g of hydrotalcite (average particle size: 150 nm, Mg / Al ratio: 3) and the previously mixed IBI WOOL slurry were put into a 3 L plastic cup, and 1.5 L of the total was added. Distilled water was added to make the volume, and the mixture was stirred for about 30 seconds. While stirring with a stirrer, 15.0 g of an aqueous solution (0.2 wt%) of PDADMAC, which is a cationic polymer, was added and stirred for about 3 minutes.
  • the obtained slurry was poured into a commercially available papermaking apparatus (manufactured by Kumagai Riki Kogyo Co., Ltd.), and the suspension mixture was deposited on a circular metal mesh (200 mesh) having a diameter of 160 mm by dehydration.
  • the formed deposit was peeled off from the mesh, pressed at 350 kPa for 3 minutes, and dried at 105 ° C. for 2 hours to obtain a sheet-like molded body.
  • the obtained sheet-like molded body was first baked at 800 ° C. for 5 hours in an air atmosphere.
  • SEM scanning electron microscope
  • the sheet-like molded body after the first firing was immersed in a 0.1 mol / L nickel nitrate aqueous solution for 1 hour, dried at 105 ° C. for 3 hours, and then subjected to second firing at 800 ° C. for 5 hours.
  • the sheet-like molded body after the second baking was subjected to a reduction treatment in 5% H 2 / N 2 at 800 ° C. for 15 hours to obtain a paper-like catalyst structure having a thickness of about 1 mm.
  • SEM scanning electron microscope
  • Example 2 A paper-like catalyst structure was obtained in the same manner as in Example 1 except that the hydrotalcite was changed to that shown in Table 1.
  • Example 3 A paper-like catalyst structure was obtained in the same manner as in Example 1 except that the hydrotalcite was changed to that shown in Table 1.
  • Example 4 As inorganic fibers, IBI WOOL J-15 (5 g) and 600 mL of distilled water were mixed with a mixer for about 3 minutes. Next, the magnetic stirrer chip, 1 g of hydrotalcite (average particle size: 150 nm, Mg / Al ratio: 3) and the previously mixed IBI WOOL slurry were put into a 3 L plastic cup, and 1.5 L in total. Distilled water was added so that the volume of the mixture became about 30 seconds, followed by stirring for about 30 seconds. While stirring with a stirrer, 15.0 g of an aqueous solution (0.2 wt%) of PDADMAC, which is a cationic polymer, was added and stirred for about 3 minutes.
  • PDADMAC a aqueous solution
  • the obtained slurry was poured into a commercially available paper making apparatus (manufactured by Kumagai Riki Kogyo Co., Ltd.), and the suspension mixture was deposited on a 160 mm circular metal mesh for filtration (200 mesh) by dehydration.
  • the formed deposit was peeled off from the mesh, pressed at 350 kPa for 3 minutes, and dried at 105 ° C. for 2 hours to obtain a sheet-like molded body.
  • the obtained sheet-like molded body was first baked at 800 ° C. for 5 hours in an air atmosphere. Subsequently, the sheet-like molded body was immersed in a 0.1 mol / L nickel nitrate aqueous solution for 1 hour, dried at 105 ° C. for 3 hours, and then subjected to second baking at 800 ° C. for 5 hours. A reduction treatment was performed for 15 hours at 800 ° C. in 5% H 2 / N 2 to obtain a paper-like catalyst structure having a thickness of about 1 mm.
  • Comparative Example 1 A paper-like catalyst structure having a thickness of about 1 mm was obtained by carrying out the same treatment as in Example 1 except that the reduction treatment was carried out in 5% H 2 / N 2 at 1000 ° C. for 1 hour.
  • Table 2 shows the analysis results of the paper-like catalyst structures obtained in Examples 1 to 4 and Comparative Example 1.
  • the paper-like catalyst structures of the examples had mechanical strength, and the nickel metal fine particles had a fine average particle size of 20 nm or less.
  • the paper-like catalyst structure of Comparative Example 1 was brittle because of the reduction at high temperature, and the size of the nickel metal fine particles was large.
  • Example 5 A paper-like catalyst structure was obtained in the same manner as in Example 1 except that the inorganic binder was changed to 1.67 g of yttria-stabilized zirconia sol (solid content concentration 30 wt%).
  • Example 6 A paper-like catalyst structure was obtained in the same manner as in Example 2 except that the inorganic binder was changed to 1.67 g of yttria-stabilized zirconia sol (solid content concentration 30 wt%).
  • Example 7 A paper-like catalyst structure was obtained in the same manner as in Example 2 except that the inorganic binder was changed to 1.67 g of ceria sol (solid content concentration 30 wt%).
  • Example 8 A paper-like catalyst structure was obtained in the same manner as in Example 3 except that the inorganic binder was changed to 1.67 g of yttria-stabilized zirconia sol (solid content concentration 30 wt%).
  • Example 9 A paper-like catalyst structure was obtained in the same manner as in Example 3 except that the inorganic binder was changed to 1.67 g of ceria sol (solid content concentration 30 wt%).
  • Table 4 shows the analysis results of the paper-like catalyst structures obtained in Examples 5 to 9.
  • Table 5 shows the characteristics of the layered double hydroxide or composite metal oxide used in Examples 1 to 9 and the analysis results of carbon deposition of the obtained paper-like catalyst structure.
  • the carbon precipitation was evaluated by observing the paper-like catalyst structure after the reforming test.
  • Table 5 classifies the carbon deposition properties according to the following criteria. Trace amount: Almost no change in the color of the surface of the catalyst structure was observed before and after the reforming test, and carbon deposition was observed on less than 10% of the surface of the catalyst structure. Less: Less than 50% of the surface of the catalyst structure is blackened due to carbon deposition. Many: 50% or more of the surface of the catalyst structure is blackened by carbon deposition.
  • the paper-like catalyst structure according to the present invention is easy to handle because it can efficiently produce hydrogen and has mechanical strength. Further, hydrogen can be efficiently produced even in a reforming reaction at a low temperature, which is suitable for dry reforming of biogas.
  • Test piece 2 Chucking 11: Paper-like catalyst structure 12: Reaction tube 13: Heating device 14: Support GC: Gas chromatograph

Abstract

The purpose of the present invention is to address the problem of providing: a paper-like catalyst structure that makes it possible to produce hydrogen efficiently in a reaction for reforming a methane-containing gas and that is provided with mechanical strength, facilitating handling; and a method for manufacturing the paper-like catalyst structure. The present invention pertains to a paper-like catalyst structure (catalyst sheet) containing an inorganic fiber obtained by firing and heat-reducing a sheet-shaped molded body, molded by a wet papermaking method, at a temperature of 950ºC or less, and a composite metal oxide containing aluminum and magnesium and supporting nickel metal microparticles having an average particle diameter of 1 to 20 nm.

Description

ペーパー状触媒構造体及びその製造方法Paper-like catalyst structure and method for producing the same
　本発明は、炭化水素を含有するガスから水素を効率よく製造するためのペーパー状触媒構造体及びその製造方法に関するものである。 The present invention relates to a paper-like catalyst structure for efficiently producing hydrogen from a gas containing hydrocarbon and a method for producing the same.
　近年、メタンを主成分として含有する都市ガス等を水蒸気により改質反応させ水素を製造し、得られた水素を燃料とした家庭用燃料電池が普及しつつある。改質反応に用いられる触媒としては、ルテニウムあるいはより安価なニッケルを、アルミナを主成分とする担体に担持し、該触媒を更にペレット状に成形した触媒が使用されている。 In recent years, household fuel cells using hydrogen produced by reforming and reacting city gas containing methane as a main component with steam to produce hydrogen are becoming widespread. As a catalyst used in the reforming reaction, a catalyst is used in which ruthenium or cheaper nickel is supported on a carrier mainly composed of alumina and the catalyst is further shaped into a pellet.
　また安価なニッケル微粒子を担持したマグネシウムとアルミニウムを含む複合金属酸化物の粉末や該粉末をペレット状に成形した改質触媒が提案されている（特許文献１、特許文献２）。 Also proposed are powders of complex metal oxides containing magnesium and aluminum carrying inexpensive nickel fine particles, and reforming catalysts in which the powders are formed into pellets (Patent Documents 1 and 2).
　触媒の成形体としては、前記ペレット状の構造体や従来のハニカム構造体とは異なるシート状に成形したペーパー状触媒構造体が提案されている（特許文献３、特許文献４）。前記ペーパー状触媒構造体は湿式抄紙法によって容易に得ることができる。更にペーパー状触媒構造体の有している特有な繊維ネットワーク構造及び該繊維ネットワーク上に担持された金属触媒により、反応ガスの反応を効率的に進行させることができると考えられている。また、形状加工性が高いとともに複数の種類のペーパー状触媒構造体を積層することで、反応性の制御も可能という優位性がある。さらにはペーパー状触媒構造体を固体酸化物形燃料電池の燃料極前段に配置した構成も提案されている（特許文献５） As a catalyst molded body, a paper-like catalyst structure molded into a sheet shape different from the pellet-shaped structure and the conventional honeycomb structure has been proposed (Patent Documents 3 and 4). The paper-like catalyst structure can be easily obtained by a wet papermaking method. Furthermore, it is considered that the reaction of the reaction gas can proceed efficiently by the unique fiber network structure possessed by the paper-like catalyst structure and the metal catalyst supported on the fiber network. Further, there is an advantage that the reactivity can be controlled by stacking a plurality of types of paper-like catalyst structures together with high shape processability. Furthermore, a configuration in which a paper-like catalyst structure is arranged in front of the fuel electrode of a solid oxide fuel cell has also been proposed (Patent Document 5).
　一方、温暖化ガスの排出量削減の取り組みとして、これまで見過ごされてきたバイオマスをエネルギーとして有効利用する試みが種々行われている。生活排水や畜産業からの排水をメタン発酵によりメタンガスと炭酸ガスの混合ガスであるバイオガスを生成し、発電可能な濃度までメタンガスを濃縮後、ガスエンジンによる発電が行われている。しかしながら、エネルギー変換効率の観点から、バイオガスからドライリフォーミングにより直接に水素と一酸化炭素へと改質し、固体酸化物形燃料電池で発電する方がより変換効率的に優れていることが知られているが、これまでに十分な改質性能を有する触媒構造体は報告されていない。 On the other hand, various attempts have been made to effectively use biomass that has been overlooked as energy as efforts to reduce greenhouse gas emissions. Biogas, which is a mixed gas of methane gas and carbon dioxide gas, is generated from domestic wastewater and wastewater from the livestock industry by methane fermentation. However, from the viewpoint of energy conversion efficiency, it is better to convert the biogas directly into hydrogen and carbon monoxide by dry reforming and to generate electricity with a solid oxide fuel cell. Although known, no catalyst structure having sufficient reforming performance has been reported so far.
　また、メタンガスを含む炭化水素の改質時に常に問題となっているのが、触媒内部に析出する炭素成分である。炭素成分は改質触媒となる金属上に析出し改質性能を劣化させる場合や、多孔質である触媒構造体内のガス拡散流路を閉塞させるなどの問題を起こしてしまう。長時間の改質性能を維持するためには炭素析出性を抑える必要がある。 Also, the carbon component deposited in the catalyst is always a problem when reforming hydrocarbons containing methane gas. When the carbon component is deposited on the metal serving as the reforming catalyst to deteriorate the reforming performance, the carbon component causes problems such as blocking the gas diffusion flow path in the porous catalyst structure. In order to maintain the reforming performance for a long time, it is necessary to suppress carbon precipitation.
　炭素析出を抑制するために比較的炭素析出の少ないルテニウムなどの貴金属が改質触媒として使われるが、ルテニウム金属は一般的に高価な材料である。そのためより安価なニッケル金属を用いる触媒が種々検討されているが、バイオガスのドライリフォーミングは可能であるが炭素析出を抑制するのは難しい。 In order to suppress carbon deposition, a noble metal such as ruthenium with relatively little carbon deposition is used as a reforming catalyst, but ruthenium metal is generally an expensive material. Therefore, various inexpensive catalysts using nickel metal have been studied, but dry reforming of biogas is possible, but it is difficult to suppress carbon deposition.
特開２００３－２２５５６６号公報JP 2003-225566 A 特開２００６－０６１７６０号公報JP 2006-061760 A 特開平６－１３４３０７号公報JP-A-6-134307 特開２０１１－９２８２５号公報JP 2011-92825 A 国際公開２０１４／０２１３８５号International Publication No. 2014/021385
　これまでに都市ガス等のメタンを主成分としたガスを水蒸気改質するペーパー状触媒構造体が提案されている（特許文献４）。しかし、特許文献４にはニッケル金属触媒を無機バインダーにて保持させたペーパー触媒のガス改質能力の向上のために１０００℃以上の焼成が必要とされている。しかし、焼成温度を上げてしまうと、触媒として作用するニッケル金属粒子が焼結して粗大化する触媒能の劣化や、ペーパー状触媒構造体を構成する一般的な耐熱性繊維では結晶性が上がるために起こる機械的強度の劣化が懸念される。ペーパー状触媒構造体の機械的強度が劣ると、工業的に製造することが困難になる、使用中の振動などで構造体に亀裂が入ると燃料ガスが漏れ、転化率の低下だけでなく燃料電池セルの電極部へのダメージが生じるなどの恐れがある。そのため、ペーパー状触媒構造体の製造はできるだけ低い温度で行うことが望ましい。 So far, a paper-like catalyst structure for steam reforming a gas mainly composed of methane such as city gas has been proposed (Patent Document 4). However, Patent Document 4 requires firing at 1000 ° C. or higher in order to improve the gas reforming ability of a paper catalyst in which a nickel metal catalyst is held by an inorganic binder. However, if the calcination temperature is raised, the nickel metal particles acting as a catalyst will sinter and become coarser, and the catalytic ability will deteriorate, and the general heat-resistant fiber constituting the paper-like catalyst structure will increase the crystallinity. Therefore, there is a concern about deterioration of mechanical strength. If the mechanical strength of the paper-like catalyst structure is inferior, it will be difficult to manufacture industrially, and if the structure cracks due to vibration during use, fuel gas leaks, not only the conversion rate decreases but also the fuel There is a risk of damage to the electrode portion of the battery cell. For this reason, it is desirable to produce the paper-like catalyst structure at the lowest possible temperature.
　メタンガスの炭酸ガスリフォーミング（ドライリフォーミング）を目的とした触媒としてハイドロタルサイトから生成し、ニッケル微粒子を含むマグネシウム及びアルミニウムの複合金属酸化物の粉体が提案されている（非特許文献１）。前記触媒は高い改質特性及び炭素析出が抑えられる触媒として非常に有効であると考えられる。しかしながら、実際にガス改質器として用いるためには触媒粉体としてではなく本発明に示すようなペーパー状触媒構造体に成形することが望ましいと考えられるが、そのような成形体にするための方法やドライリフォーミングを行ったときの改質性評価はこれまで行われていない。 As a catalyst for carbon dioxide reforming (dry reforming) of methane gas, a composite metal oxide powder of magnesium and aluminum produced from hydrotalcite and containing nickel fine particles has been proposed (Non-patent Document 1). The catalyst is considered to be very effective as a catalyst that has high reforming characteristics and suppresses carbon deposition. However, for actual use as a gas reformer, it is considered desirable to form a paper-like catalyst structure as shown in the present invention rather than as a catalyst powder. There has been no evaluation of reformability when a method or dry reforming is performed.
　また、バイオガスの改質試験後には炭素析出が見られる場合があり、より長時間の安定した改質性を維持するためには、ペーパー状触媒構造体の組成及び製造方法を改善する必要があった。 In addition, carbon deposition may be observed after the biogas reforming test, and it is necessary to improve the composition and manufacturing method of the paper-like catalyst structure in order to maintain stable reforming for a longer time. there were.
　本発明は、このような事情に鑑みて、水素を効率よく製造するためのペーパー状触媒構造体を提供することを目的とする。特に、本発明は、バイオガスのドライリフォーミング時において効率よく水素を製造させるため、改質反応を低温で行うことができるペーパー状触媒構造体を提供する。また、バイオガスのドライリフォーミング時において耐炭素析出性の高いペーパー状触媒構造体を提供する。 In view of such circumstances, an object of the present invention is to provide a paper-like catalyst structure for efficiently producing hydrogen. In particular, the present invention provides a paper-like catalyst structure capable of performing the reforming reaction at a low temperature in order to efficiently produce hydrogen during biogas dry reforming. Further, the present invention provides a paper-like catalyst structure having a high carbon deposition resistance during dry reforming of biogas.
　本発明者は、上記課題を解決すべく誠意研究を重ねた結果、下記の発明が目的に合致することを見出し、本発明に至った。 As a result of conducting sincerity studies to solve the above problems, the present inventor has found that the following invention meets the purpose, and has reached the present invention.
　本発明は、無機繊維と平均粒子径が１～２０ｎｍであるニッケル金属微粒子が担持されたマグネシウム及びアルミニウムを含有する複合金属酸化物とを含むペーパー状触媒構造体（触媒シート）である（本発明１）。 The present invention is a paper-like catalyst structure (catalyst sheet) comprising inorganic fibers and a composite metal oxide containing magnesium and aluminum on which nickel metal fine particles having an average particle diameter of 1 to 20 nm are supported (the present invention). 1).
　また、本発明は、無機繊維がアルミナ、シリカ、ジルコニア、セリアから選ばれる一種以上を含む繊維である本発明１記載のペーパー状触媒構造体（触媒シート）である（本発明２）。 Further, the present invention is a paper-like catalyst structure (catalyst sheet) according to the first aspect of the present invention, wherein the inorganic fiber is a fiber containing at least one selected from alumina, silica, zirconia, and ceria (Invention 2).
　また、本発明は、無機繊維が低結晶性繊維を含む本発明１又は２に記載のペーパー状触媒構造体（触媒シート）である（本発明３）。 Further, the present invention is the paper-like catalyst structure (catalyst sheet) according to the first or second aspect of the present invention, wherein the inorganic fibers include low crystalline fibers (Invention 3).
　また、本発明は、無機繊維、無機バインダー並びにマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子を含むスラリーを湿式抄紙法によってシート状成形体とし、該成形体を５００℃以上９５０℃以下の温度で焼成後、ニッケル化合物を溶解した水溶液に浸漬し、乾燥後、７００℃以上９５０℃以下の温度で加熱還元することを特徴とする本発明１～３のいずれかに記載のペーパー状触媒構造体（触媒シート）の製造方法である（本発明４）。 In addition, the present invention provides a sheet-like formed body by a wet papermaking method using a slurry containing inorganic fibers, an inorganic binder, and layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum, The molded body is fired at a temperature of 500 ° C. or more and 950 ° C. or less, immersed in an aqueous solution in which a nickel compound is dissolved, dried, and then heated and reduced at a temperature of 700 ° C. or more and 950 ° C. or less. 3. A method for producing a paper-like catalyst structure (catalyst sheet) according to any one of 3 (present invention 4).
　また、本発明は、無機繊維、無機バインダー並びにマグネシウム、アルミニウム及びニッケルを含有する層状複水酸化物粒子又はマグネシウム、アルミニウム及びニッケルを含有する複合金属酸化物粒子を含むスラリーを湿式抄紙法によってシート状成形体とし、該成形体を５００℃以上９５０℃以下の温度で焼成、続いて７００℃以上９５０℃以下の温度で加熱還元することを特徴とする本発明１～３のいずれかに記載のペーパー状触媒構造体（触媒シート）の製造方法である（本発明５）。 Further, the present invention provides a slurry containing inorganic fibers, inorganic binders and layered double hydroxide particles containing magnesium, aluminum and nickel or composite metal oxide particles containing magnesium, aluminum and nickel by a wet papermaking method. The paper according to any one of the present inventions 1 to 3, wherein the paper is formed into a formed body, and the formed body is fired at a temperature of 500 ° C. or higher and 950 ° C. or lower and subsequently heated and reduced at a temperature of 700 ° C. or higher and 950 ° C. or lower. Is a method for producing a catalyst structure (catalyst sheet) (Invention 5).
　また、本発明は６００℃で５時間焼成した後のＢＥＴ比表面積が１００ｍ２／ｇ以下になる層状複水酸化物粒子又は複合金属酸化物粒子を用いる本発明４又は５に記載のペーパー状触媒構造体（触媒シート）の製造方法である（本発明６）。 In addition, the present invention provides the paper-like catalyst according to the present invention 4 or 5 using layered double hydroxide particles or composite metal oxide particles having a BET specific surface area of 100 m 2 / g or less after calcination at 600 ° C. for 5 hours. It is a manufacturing method of a structure (catalyst sheet) (Invention 6).
　本発明のペーパー状触媒構造体は、ニッケル金属の微細な粒子が担持されており、メタンなどの炭化水素含有ガスから水素を効率よく製造することができる。また、低温で改質反応を行った場合でも高い改質特性を備えているために、メタンガスと炭酸ガスの混合ガスであるバイオガスのドライリフォーミングにおいても水素を効率よく製造することができる。 The paper-like catalyst structure of the present invention carries fine particles of nickel metal and can efficiently produce hydrogen from a hydrocarbon-containing gas such as methane. In addition, even when the reforming reaction is performed at a low temperature, high reforming characteristics are provided, so that hydrogen can be efficiently produced even in dry reforming of biogas which is a mixed gas of methane gas and carbon dioxide gas.
　また、本発明のペーパー状触媒構造体は、触媒構造体中に含まれる複合金属酸化物粒子によって、耐炭素析出性を高めることができるため、触媒構造体中でのガス拡散領域の閉塞もなく長時間の安定した改質反応を維持することができる。 Further, the paper-like catalyst structure of the present invention can improve the carbon precipitation resistance by the composite metal oxide particles contained in the catalyst structure, so that there is no blockage of the gas diffusion region in the catalyst structure. A stable reforming reaction for a long time can be maintained.
　また、本発明のペーパー状触媒構造体の製造方法によれば、ペーパー状触媒構造体上に容易にニッケル金属の微細な粒子を担持することができ、水素を効率よく製造することができるペーパー状触媒構造体を製造することができる。 Further, according to the method for producing a paper-like catalyst structure of the present invention, a paper-like catalyst structure that can easily carry fine nickel metal particles on the paper-like catalyst structure and can efficiently produce hydrogen. A catalyst structure can be produced.
強度試験方法Strength test method 改質試験機Reforming tester
　本発明に係るペーパー状触媒構造体は、無機繊維と平均粒子径が２０ｎｍ以下であるニッケル金属微粒子が担持されたマグネシウム及びアルミニウムを含有する複合金属酸化物とを含む。本発明において「ペーパー状」とは、本発明の触媒構造体が上記成分を含む触媒シートまたは触媒無機繊維シートであり、無機繊維を構成成分として抄紙装置などで紙を製造する方法で得られるものであり、紙のような無機繊維の集合体としての性質を有することを意味する。そのため、便宜上「ペーパー状」と記載する。 The paper-like catalyst structure according to the present invention includes inorganic fibers and a composite metal oxide containing magnesium and aluminum on which nickel metal fine particles having an average particle diameter of 20 nm or less are supported. In the present invention, the “paper” is a catalyst sheet or a catalyst inorganic fiber sheet in which the catalyst structure of the present invention contains the above-mentioned components, and is obtained by a method of producing paper using a paper making apparatus or the like using inorganic fibers as constituent components It means having properties as an aggregate of inorganic fibers such as paper. Therefore, it is described as “paper” for convenience.
　本発明に係るペーパー状触媒構造体（触媒シート）の厚さは、使用する無機繊維の種類や抄き込む酸化物粒子の種類、量にもよるが、通常０．５～３ｍｍである。厚さが３ｍｍを超えると形状加工性が悪化し、厚さが０．５ｍｍ未満であると触媒構造体としての強度が不足する。 The thickness of the paper-like catalyst structure (catalyst sheet) according to the present invention is usually 0.5 to 3 mm, although it depends on the type of inorganic fiber used and the type and amount of oxide particles to be formed. When the thickness exceeds 3 mm, the shape workability deteriorates, and when the thickness is less than 0.5 mm, the strength as the catalyst structure is insufficient.
　上記ペーパー状触媒構造体を構成する無機繊維としては、本発明のペーパー状触媒構造体の使用条件での熱的安定性、化学的安定性が高い無機物からなる繊維体を用いることができる。無機物としては、金属酸化物、金属炭化物、金属窒化物などが挙げられ、通常、金属酸化物である。このような無機物からなる繊維体としては、アルミナや、アルミナとシリカを主成分とする繊維体などが挙げられる。 As the inorganic fiber constituting the paper-like catalyst structure, a fiber body made of an inorganic substance having high thermal stability and chemical stability under the use conditions of the paper-like catalyst structure of the present invention can be used. Examples of inorganic substances include metal oxides, metal carbides, and metal nitrides, and are usually metal oxides. Examples of the fiber body made of such an inorganic material include alumina and fiber bodies mainly composed of alumina and silica.
　本発明に係るペーパー状触媒構造体は、無機繊維の一部としてイオン伝導性酸化物繊維を併用しても良い。イオン伝導性酸化物を併用することにより炭素析出を抑制する助触媒としての作用がある。イオン伝導性酸化物としては、ジルコニア（ＺｒＯ２）系酸化物、セリア（ＣｅＯ２）系酸化物などが挙げられるが、特に高温還元雰囲気中での化学的安定性が高いことからイオン伝導性酸化物繊維として、安定化ジルコニア繊維を含むことが好ましい。安定化ジルコニアとしては、イットリア安定化ジルコニア（ＹＳＺ）、スカンジア安定化ジルコニア（ＳｃＳＺ）、カルシア安定化ジルコニア（ＣａＳＺ）などが挙げられる。これらの中でも、イットリア安定化ジルコニア（ＹＳＺ）が、コスト、安定性の点で好ましく使用される。 The paper-like catalyst structure according to the present invention may use ion conductive oxide fibers in combination as part of the inorganic fibers. By using an ion conductive oxide in combination, it acts as a promoter for suppressing carbon deposition. Examples of ion conductive oxides include zirconia (ZrO 2 ) -based oxides and ceria (CeO 2 ) -based oxides, and the ion-conductive oxide is particularly high because of its high chemical stability in a high-temperature reducing atmosphere. It is preferable that a stabilized zirconia fiber is included as a physical fiber. Examples of the stabilized zirconia include yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), and calcia stabilized zirconia (CaSZ). Among these, yttria-stabilized zirconia (YSZ) is preferably used in terms of cost and stability.
　上記ペーパー状触媒構造体を構成する無機繊維は、低結晶性繊維を含むことが好ましい。低結晶性繊維を含むことによって、ペーパー状触媒構造体が高い機械的強度とじん性を備えたものとなる。低結晶性繊維としては、例えば、アルミナとシリカを主成分とする繊維体であって非晶質のリフラクトリーセラミックファイバー（例えば、イビデン株式会社製ＩＢＩ　ＷＯＯＬ（登録商標）、イソライト工業株式会社製イソウール（登録商標））や低結晶性のアルミナファイバー（例えば、電気化学工業株式会社製デンカアルセン（登録商標）　Ｂ８０Ｌ）等であることが好ましい。また、ペーパー状触媒構造体の製造工程において、９５０℃を超える高温での加熱を経ることなく、無機繊維の低結晶性が維持されていることが好ましい。低結晶性繊維は、ペーパー状触媒構造体を構成する無機繊維のうち、３０％以上であることが好ましい。 It is preferable that the inorganic fiber constituting the paper-like catalyst structure includes a low crystalline fiber. By including the low crystalline fiber, the paper-like catalyst structure has high mechanical strength and toughness. As the low crystalline fiber, for example, an amorphous refractory ceramic fiber (for example, IBI WOOL (registered trademark) manufactured by Ibiden Co., Ltd., isowool manufactured by Isolite Industrial Co., Ltd.) is a fiber body mainly composed of alumina and silica. (Registered trademark)) or low crystalline alumina fiber (for example, Denka Arsen (registered trademark) B80L manufactured by Denki Kagaku Kogyo Co., Ltd.) is preferable. Moreover, in the manufacturing process of a paper-like catalyst structure, it is preferable that the low crystallinity of an inorganic fiber is maintained, without passing through the high temperature exceeding 950 degreeC. The low crystalline fiber is preferably 30% or more of the inorganic fibers constituting the paper-like catalyst structure.
　ペーパー状触媒構造体を構成する無機繊維は、無機バインダー成分によってそれぞれが結着される。 The inorganic fibers constituting the paper-like catalyst structure are bound by the inorganic binder component.
　本発明に係るペーパー状触媒構造体に含まれるマグネシウム及びアルミニウムを含有する複合金属酸化物は、マグネシウムとアルミニウムの組成比の比率が３：１～１．５：１であることが好ましい。 In the composite metal oxide containing magnesium and aluminum contained in the paper-like catalyst structure according to the present invention, the ratio of the composition ratio of magnesium and aluminum is preferably 3: 1 to 1.5: 1.
　本発明に係るペーパー状触媒構造体に含まれるマグネシウム及びアルミニウムを含有する複合金属酸化物には、平均粒子径が１～２０ｎｍであるニッケル金属微粒子が担持されている。複合金属酸化物に担持される金属ニッケルの平均粒子径を１ｎｍ未満とすることは困難である。ニッケル金属微粒子の平均粒子径が２０ｎｍを超えると触媒の初期活性が低下すると同時に耐炭素析出性が悪くなる。ニッケル金属微粒子の平均粒子径は、好ましくは１～１８ｎｍ、より好ましくは２～１５ｎｍである。 The composite metal oxide containing magnesium and aluminum contained in the paper-like catalyst structure according to the present invention carries nickel metal fine particles having an average particle diameter of 1 to 20 nm. It is difficult to make the average particle diameter of metallic nickel supported on the composite metal oxide less than 1 nm. When the average particle diameter of the nickel metal fine particles exceeds 20 nm, the initial activity of the catalyst is lowered and the carbon deposition resistance is deteriorated. The average particle diameter of the nickel metal fine particles is preferably 1 to 18 nm, more preferably 2 to 15 nm.
　ニッケル金属微粒子の粒子径は、走査透過型電子顕微鏡（ＳＴＥＭ）にて観察し、マグネシウム及びアルミニウムを含有する複合金属酸化物上に存在するニッケル金属微粒子から計測することができる。 The particle diameter of the nickel metal fine particles is observed with a scanning transmission electron microscope (STEM), and can be measured from the nickel metal fine particles present on the composite metal oxide containing magnesium and aluminum.
　ペーパー状触媒構造体に含まれるニッケルの量はペーパー状触媒構造体の用途、原料ガスの組成などに応じて適宜選択されるが、通常、ペーパー状触媒構造体全体を１００重量％としたときに、ニッケル元素換算で１～２０重量％の範囲である。 The amount of nickel contained in the paper-like catalyst structure is appropriately selected according to the use of the paper-like catalyst structure, the composition of the raw material gas, etc., but usually when the entire paper-like catalyst structure is 100% by weight And in the range of 1 to 20% by weight in terms of nickel element.
　本発明に係るペーパー状触媒構造体は、ＢＥＴ比表面積が５ｍ２／ｇ以上であることが好ましい。ＢＥＴ比表面積が５ｍ２／ｇより小さいと炭化水素を含有するガスとニッケル微粒子との接触面積が小さくなり、結果、転化率が悪くなり好ましくない。ＢＥＴ比表面積は６ｍ２／ｇ以上であることがより好ましく、更により好ましくは６～２０ｍ２／ｇである。ＢＥＴ比表面積の調整は、ペーパー状触媒構造体に抄き込むマグネシウム、アルミニウム及びニッケルを含有する層状複水酸化物粒子又はマグネシウム、アルミニウム及びニッケルを含有する複合金属酸化物粒子の種類および量によって行う。 The paper-like catalyst structure according to the present invention preferably has a BET specific surface area of 5 m 2 / g or more. If the BET specific surface area is smaller than 5 m 2 / g, the contact area between the hydrocarbon-containing gas and the nickel fine particles becomes small, resulting in a poor conversion rate. The BET specific surface area is more preferably 6 m 2 / g or more, and even more preferably 6 to 20 m 2 / g. The BET specific surface area is adjusted by the type and amount of layered double hydroxide particles containing magnesium, aluminum and nickel or composite metal oxide particles containing magnesium, aluminum and nickel incorporated into the paper-like catalyst structure. .
　本発明に係るペーパー状触媒構造体の強度は、例えば図１に示すように試験片の上下をつかんで引っ張った際に試験片が断裂するまでの最大荷重で計測ことができる。厚さ１ｍｍ程度のペーパー状触媒構造体を５０ｍｍ×１５ｍｍの短冊状に切断した試験片を、上下を３０ｍｍの間隔で５ｍｍ幅のつかみ部でチャッキングして引っ張り速度１００ｍｍ／ｍｉｎで引っ張った場合においては、試験片が断裂するまでの最大荷重が１．０（Ｎ）以上であることが好ましい。最大荷重が１．０（Ｎ）未満のときにはペーパー状触媒構造体が脆いため取扱いが容易でない。 The strength of the paper-like catalyst structure according to the present invention can be measured by, for example, the maximum load until the test piece is torn when the test piece is held and pulled as shown in FIG. When a test piece obtained by cutting a paper-like catalyst structure having a thickness of about 1 mm into a strip of 50 mm × 15 mm is chucked with a gripping portion having a width of 5 mm at intervals of 30 mm and pulled at a pulling speed of 100 mm / min. The maximum load until the test piece is torn is preferably 1.0 (N) or more. When the maximum load is less than 1.0 (N), handling is not easy because the paper-like catalyst structure is brittle.
　次に、本発明に係るペーパー状触媒構造体の製造方法を述べる。 Next, a method for producing a paper-like catalyst structure according to the present invention will be described.
　本発明に係るペーパー状触媒構造体は、無機繊維、無機バインダー並びにマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子を含むスラリーを湿式抄紙法によってシート状成形体とし、該成形体を焼成後、ニッケル化合物を溶解した水溶液に浸漬し、乾燥、焼成後、加熱還元することによって製造することができる。 The paper-like catalyst structure according to the present invention is a sheet formed by wet papermaking using a slurry containing inorganic fibers, an inorganic binder, and layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum. It can be produced by forming a shaped molded body, dipping the molded body in an aqueous solution in which a nickel compound is dissolved, drying, firing, and heat reduction.
　以下に市販の抄紙装置を用いた場合のシート状成形体の作成について一例を記述するが、製造法を限定するものではない。各製紙装置に合わせて量や材料あるいは添加手順を最適化して選ぶことができる。 Hereinafter, an example of the production of a sheet-like molded product using a commercially available paper making apparatus will be described, but the production method is not limited. The amount, material, or addition procedure can be optimized and selected for each papermaking apparatus.
　まず、無機繊維、無機バインダー並びにマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子、及び必要に応じて他の成分（気孔量調製剤、分散剤等）を溶媒にいれて、均一になるまで分散させたスラリーを作製する。 First, inorganic fiber, inorganic binder and layered double hydroxide particles containing magnesium and aluminum, or composite metal oxide particles containing magnesium and aluminum, and other components as necessary (porosity adjusting agent, dispersant, etc.) ) In a solvent to prepare a slurry dispersed until uniform.
　スラリーの溶媒には水、アルコール類、水溶性のケトン類を用いることができる。 Water, alcohols, and water-soluble ketones can be used as the slurry solvent.
　無機繊維は、前述のとおり、本発明のペーパー状触媒構造体の使用条件での熱的安定性、化学的安定性が高い無機物からなる種々の繊維体を用いることができる。 As described above, as the inorganic fiber, various fiber bodies made of an inorganic material having high thermal stability and chemical stability under the use conditions of the paper-like catalyst structure of the present invention can be used.
　無機繊維の長さ及び太さは、ペーパー状触媒構造体を形成できる範囲であればよく、本発明のペーパー状触媒構造体の用途等を考慮して適宜決定される。通常、平均全長３０μｍ～６ｍｍ、好ましくは５０μｍ～３ｍｍ、平均直径が１～２０μｍ、好ましくは４～１０μｍで、最低繊維径が３．０μｍ以上であることが作業環境上好ましい。なお、無機繊維の長さ、太さは、走査型電子顕微鏡（ＳＥＭ）で確認することができる。 The length and thickness of the inorganic fiber may be within a range in which a paper-like catalyst structure can be formed, and is appropriately determined in consideration of the use of the paper-like catalyst structure of the present invention. In general, it is preferable in the working environment that the average total length is 30 μm to 6 mm, preferably 50 μm to 3 mm, the average diameter is 1 to 20 μm, preferably 4 to 10 μm, and the minimum fiber diameter is 3.0 μm or more. In addition, the length and thickness of inorganic fiber can be confirmed with a scanning electron microscope (SEM).
　無機バインダー成分としては、本発明のペーパー状触媒構造体の使用条件において、十分な化学的安定性を有し、且つ、無機繊維を十分な機械的強度に結着できるものであれば、従来公知の無機バインダーを使用できる。例えば市販されているアルミナゾル、ジルコニアゾルあるいはセリアゾルを使用することができる。炭素析出の抑制効果を考慮するとジルコニアゾルあるいはセリアゾルがより好ましい。 As the inorganic binder component, conventionally known as long as it has sufficient chemical stability under the conditions of use of the paper-like catalyst structure of the present invention and can bind inorganic fibers to sufficient mechanical strength. Inorganic binders can be used. For example, commercially available alumina sol, zirconia sol, or ceria sol can be used. Considering the effect of suppressing carbon deposition, zirconia sol or ceria sol is more preferable.
　スラリーにおける無機バインダーの量は、無機繊維１００重量部に対して無機バインダーの固形分として１重量部～７０重量部であることが好ましい。 The amount of the inorganic binder in the slurry is preferably 1 to 70 parts by weight as the solid content of the inorganic binder with respect to 100 parts by weight of the inorganic fibers.
　ペーパー状触媒構造体に含まれるマグネシウム及びアルミニウムを含有する複合金属酸化物の前駆体はハイドロタルサイト様化合物であることが好ましい。前記スラリーを作製する過程においては、ハイドロタルサイト様化合物であるマグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又は、ハイドロタルサイト様化合物の層間水が脱離したマグネシウム及びアルミニウムを含有する複合金属酸化物を溶媒に添加することが好ましい。 The precursor of the composite metal oxide containing magnesium and aluminum contained in the paper-like catalyst structure is preferably a hydrotalcite-like compound. In the process of preparing the slurry, layered double hydroxide particles containing magnesium and aluminum which are hydrotalcite-like compounds, or a composite containing magnesium and aluminum from which interlayer water of hydrotalcite-like compounds has been released. It is preferred to add a metal oxide to the solvent.
　ハイドロタルサイト様化合物は加熱により構造中から脱水と脱炭酸が生じて複合金属酸化物となるが、その後、水溶液中に浸漬させることでハイドロタルサイト様化合物の層状構造が再生されることが知られている。この時にニッケルイオンを溶解させた水溶液に浸漬させることで層状構造の再生とともにマグネシウムイオンの一部がニッケルイオンと置換される。その後、加熱還元するとニッケルイオンが金属微粒子となり析出することが知られている。あるいはニッケルイオンをマグネシウムイオンの一部に代えて混合して、ハイドロタルサイト様化合物を調製し、続いて加熱還元することでもニッケルの金属微粒子が析出することが知られている（非特許文献２）。 The hydrotalcite-like compound is dehydrated and decarboxylated from the structure by heating to become a composite metal oxide, but afterwards it is known that the layered structure of the hydrotalcite-like compound is regenerated by immersion in an aqueous solution. It has been. At this time, by immersing in an aqueous solution in which nickel ions are dissolved, a part of magnesium ions is replaced with nickel ions while the layered structure is regenerated. Thereafter, it is known that nickel ions become fine metal particles when heated and reduced. Alternatively, it is known that nickel metal fine particles are precipitated by mixing a nickel ion in place of a part of magnesium ion to prepare a hydrotalcite-like compound, followed by heat reduction (Non-patent Document 2). ).
　スラリーに添加するマグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子は、平均粒子径が好ましくは５０～５００ｎｍであることが好ましく、更に好ましくは７０～１５０ｎｍである。 The layered double hydroxide particles containing magnesium and aluminum added to the slurry or the composite metal oxide particles containing magnesium and aluminum preferably have an average particle size of preferably 50 to 500 nm, more preferably 70. ~ 150 nm.
　スラリーに添加するマグネシウム及びアルミニウムを含有する層状複水酸化物、又はマグネシウム及びアルミニウムを含有する複合金属酸化物のマグネシウムとアルミニウムの組成比の比率は３：１～１．５：１であることが好ましい。 The ratio of the composition ratio of magnesium to aluminum in the layered double hydroxide containing magnesium and aluminum added to the slurry or the composite metal oxide containing magnesium and aluminum should be 3: 1 to 1.5: 1. preferable.
　本発明に用いるマグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子は、６００℃の温度で加熱焼成した後のＢＥＴ比表面積が１００ｍ２／ｇを超えないことが耐炭素析出性向上のために好ましい。ＢＥＴ比表面積を上記範囲に調整するにはマグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子の粒子径や組成比を調整して行うことができる。なお、スラリーに添加するマグネシウム及びアルミニウムを含有する層状複水酸化物、又はマグネシウム及びアルミニウムを含有する複合金属酸化物は、６００℃での加熱焼成を経たものでなくてよい。 The layered double hydroxide particles containing magnesium and aluminum used in the present invention or the composite metal oxide particles containing magnesium and aluminum have a BET specific surface area of 100 m 2 / g after being heated and fired at a temperature of 600 ° C. It is preferable not to exceed the carbon deposition resistance. The BET specific surface area can be adjusted to the above range by adjusting the particle size and composition ratio of the layered double hydroxide particles containing magnesium and aluminum, or the composite metal oxide particles containing magnesium and aluminum. . Note that the layered double hydroxide containing magnesium and aluminum added to the slurry, or the composite metal oxide containing magnesium and aluminum does not have to be heated and fired at 600 ° C.
　耐炭素析出性が向上される明確な理由は不明であるが、以下のように考えている。 The clear reason why the carbon precipitation resistance is improved is unknown, but it is considered as follows.
　６００℃の加熱条件下で１００ｍ２／ｇより大きなＢＥＴ比表面積を有するマグネシウム及びアルミニウムを含む層状複水酸化物あるいはマグネシウム及びアルミニウムを含む複合金属酸化物は、ペーパー状触媒構造体を作製する加熱焼成工程時に、５００～６００℃付近で、同時に存在する無機バインダーと強く相互作用し、無機バインダー同士の溶融や粒子成長を阻害する。そのため、ペーパー状触媒構造体中に微細な無機バインダーが存在することになる。この微細な無機バインダーがペーパー状触媒構造体中に残ってしまう。この微細な無機バインダー上においてバイオガス中のメタン成分の熱分解が顕著に生じ、結果、炭素が析出してくると考えている。一方で、６００℃の加熱条件下でＢＥＴ比表面積が１００ｍ２／ｇより小さいマグネシウム及びアルミニウムを含む層状複水酸化物あるいはマグネシウム及びアルミニウムを含む複合金属酸化物は、無機バインダーとの相互作用が小さいかあるいはほとんどなく、ペーパー状触媒構造体を作製する加熱焼成工程時において無機バインダー同士での溶融や粒子成長が生じ、メタンの熱分解反応が生じ難く、結果、炭素析出の要因とならないと考えている。本発明において、後述する実施例に示す改質試験後のペーパー状触媒構造体の炭素析出性の評価方法において、微量（改質試験の前後でほとんど触媒構造体の表面の色に変化が見られず、触媒構造体の表面の１０％未満に炭素の析出が認められる）であることが好ましい。 A layered double hydroxide containing magnesium and aluminum or a composite metal oxide containing magnesium and aluminum having a BET specific surface area of greater than 100 m 2 / g under heating conditions of 600 ° C. is heated and fired to produce a paper-like catalyst structure During the process, it strongly interacts with the inorganic binder present at around 500 to 600 ° C., thereby inhibiting the melting and particle growth of the inorganic binder. Therefore, a fine inorganic binder exists in the paper-like catalyst structure. This fine inorganic binder remains in the paper-like catalyst structure. It is believed that thermal decomposition of the methane component in the biogas occurs remarkably on this fine inorganic binder, and as a result, carbon is deposited. On the other hand, a layered double hydroxide containing magnesium and aluminum having a BET specific surface area of less than 100 m 2 / g under a heating condition of 600 ° C. or a composite metal oxide containing magnesium and aluminum has a small interaction with an inorganic binder. Or almost no melting and particle growth between the inorganic binders during the heating and baking process for producing the paper-like catalyst structure, and the thermal decomposition reaction of methane hardly occurs, and as a result, it does not cause carbon precipitation. Yes. In the present invention, in the method for evaluating the carbon deposition of the paper-like catalyst structure after the reforming test shown in the examples described later, a slight amount (a change in the color of the surface of the catalyst structure is almost seen before and after the reforming test). It is preferable that carbon is deposited on less than 10% of the surface of the catalyst structure).
　スラリーにおけるマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子の量は、無機繊維１００重量部に対して１重量部～７０重量部であることが好ましい。 The amount of the layered double hydroxide particles containing magnesium and aluminum or the composite metal oxide particles containing magnesium and aluminum in the slurry is preferably 1 part by weight to 70 parts by weight with respect to 100 parts by weight of the inorganic fibers. .
　また、マグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子は、スラリーを作製する際に、予めニッケル、ルテニウム等の金属又は金属酸化物を含んでいても良い。 The layered double hydroxide particles containing magnesium and aluminum, or the composite metal oxide particles containing magnesium and aluminum contain a metal or metal oxide such as nickel or ruthenium in advance when the slurry is prepared. May be.
　マグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子は、ペーパー状触媒構造体中に均一に分散させることを目的に、必要に応じて粒子を分散剤中に予め分散させていても良い。また、分散剤などを添加していても良い。 The layered double hydroxide particles containing magnesium and aluminum or the composite metal oxide particles containing magnesium and aluminum are dispersed as necessary in order to disperse them uniformly in the paper-like catalyst structure. It may be dispersed in advance. Further, a dispersant or the like may be added.
　スラリーには、パルプを加えることが好ましい。パルプは、抄造後の湿潤状態の強度を確保し、ろ過用メッシュからの焼成前のシート状成形体の採取を容易にする。また、パルプはシート状成形体の焼成中に焼失し、空隙（拡散パス）を生成するため、ペーパー状触媒構造体内部の気孔調製ができる。パルプの量は無機繊維１００重量部に対し１重量部～１００重量部、好ましくは１重量部～５０重量部である。パルプは予め叩解処理した物を用いるのが好ましい。 It is preferable to add pulp to the slurry. The pulp ensures the strength in the wet state after paper making, and facilitates the collection of the sheet-like molded body before firing from the mesh for filtration. Further, since the pulp is burned off during the firing of the sheet-like molded body and voids (diffusion paths) are generated, the pores inside the paper-like catalyst structure can be adjusted. The amount of the pulp is 1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the inorganic fibers. It is preferable to use a pulp that has been beaten in advance.
　前記スラリーにイオン性ポリマーなどの凝集剤を添加してフロックを生成し、そのフロックに水力学的せん断力を加えて崩壊させると同時に２００メッシュの抄き網を用いて脱水・抄造し、均質なシート状の複合体を得る。得られたシート状複合体を乾燥し、熱処理及び加圧処理を行うことにより、均一な厚さのシート状成形体を得る。 A floc is formed by adding a flocculant such as an ionic polymer to the slurry, and the floc is collapsed by applying a hydraulic shear force. A sheet-like composite is obtained. The obtained sheet-like composite is dried and subjected to heat treatment and pressure treatment to obtain a sheet-like molded article having a uniform thickness.
　続いて、シート状成形体を５００℃以上９５０℃以下の温度範囲で焼成する（第一焼成）。焼成時の焼成雰囲気は、空気や不活性ガス（窒素ガス、アルゴンガス等）等が用いられるが、通常は空気が用いられる。焼成によりシート状成形体に含まれる有機物成分を除去するとともに、無機バインダーが溶融する温度域まで加熱することで、マグネシウム及びアルミニウムを含有する複合金属酸化物を無機繊維に結着させるとともに無機繊維同士の結着を行う。焼成温度が９５０℃より高い場合には後述する加熱還元時に微細なニッケル粒子の析出が起きにくくなり、ガス改質効率が低下するため好ましくない。焼成温度が５００℃より低いと無機バインダーが十分に溶融せずペーパー状触媒構造体の強度が落ちてしまうため好ましくない。焼成温度は好ましくは７００℃～９５０℃であり、より好ましくは８００℃～９００℃である。 Subsequently, the sheet-like molded body is fired in a temperature range of 500 ° C. or more and 950 ° C. or less (first firing). Air, inert gas (nitrogen gas, argon gas, etc.), etc. are used for the baking atmosphere at the time of baking, but air is usually used. By removing the organic component contained in the sheet-like molded body by firing and heating to a temperature range where the inorganic binder melts, the composite metal oxide containing magnesium and aluminum is bound to the inorganic fiber and the inorganic fibers are bonded together. Do the binding. When the firing temperature is higher than 950 ° C., precipitation of fine nickel particles is difficult to occur at the time of heat reduction described later, and gas reforming efficiency is lowered, which is not preferable. When the calcination temperature is lower than 500 ° C., the inorganic binder is not sufficiently melted and the strength of the paper-like catalyst structure is lowered, which is not preferable. The firing temperature is preferably 700 ° C. to 950 ° C., more preferably 800 ° C. to 900 ° C.
　特に、ハイドロタルサイト様化合物を前駆体とするマグネシウム及びアルミニウムを含有する複合金属酸化物は、１０００℃程度の加熱によってスピネル構造が成長しはじめる。スピネル構造となった化合物は、水溶液に浸漬してもハイドロタルサイト様化合物に再生し難くなり、併せてマグネシウムイオンとニッケルイオンの置換も生じ難くなり、その後の加熱還元時に微細なニッケル金属粒子を得ることが困難になる。従って、スピネル構造の化合物が生成しない、あるいはわずかに生成する程度の温度域で焼成することが好ましい。 In particular, in the case of a composite metal oxide containing magnesium and aluminum having a hydrotalcite-like compound as a precursor, a spinel structure starts to grow by heating at about 1000 ° C. A compound having a spinel structure is difficult to regenerate into a hydrotalcite-like compound even when immersed in an aqueous solution, and at the same time, it is difficult for substitution of magnesium ions and nickel ions to occur. It becomes difficult to obtain. Therefore, it is preferable to perform firing in a temperature range in which a spinel structure compound is not generated or is slightly generated.
　また、ニッケルを含むハイドロタルサイト様化合物を前駆体とするマグネシウム及びアルミニウムを含有する複合金属酸化物においても、１０００℃程度の加熱によってスピネル構造が成長してくると、同様にその後の加熱還元において微細なニッケル金属粒子を得ることが困難になる。 In addition, in a composite metal oxide containing magnesium and aluminum having a hydrotalcite-like compound containing nickel as a precursor, when a spinel structure grows by heating at about 1000 ° C., similarly in subsequent heating reduction It becomes difficult to obtain fine nickel metal particles.
　また、焼成温度が９５０℃より高い場合には、無機繊維の結晶化が過度に進み、ペーパー状触媒体の機械的強度が低下するため好ましくない。 Further, when the firing temperature is higher than 950 ° C., the crystallization of inorganic fibers proceeds excessively, and the mechanical strength of the paper-like catalyst body is lowered, which is not preferable.
　その後、焼成したシート状成形体をニッケル化合物を溶解させた水溶液中に浸漬し、乾燥してニッケルを含む複合金属酸化物が抄き込まれ、焼成したシート状成形体を得ることができる。ニッケル化合物は硝酸塩、硫酸塩、炭酸塩、酢酸塩、ハロゲン化物、アンモニウム塩、シュウ酸塩等を適時選択すれば良い。ニッケル化合物水溶液中のニッケルの濃度は０．１ｍｏｌ／Ｌ～１ｍｏｌ／Ｌであることが好ましい。 Thereafter, the fired sheet-like molded body is dipped in an aqueous solution in which a nickel compound is dissolved and dried to incorporate a composite metal oxide containing nickel, whereby a fired sheet-like molded body can be obtained. As the nickel compound, nitrates, sulfates, carbonates, acetates, halides, ammonium salts, oxalates and the like may be selected as appropriate. The concentration of nickel in the aqueous nickel compound solution is preferably 0.1 mol / L to 1 mol / L.
　ニッケル化合物を溶解させた水溶液中にシート状成形体を浸漬した後、シート状成形体を水洗してもよい。水洗を行うことによって、シート状成形体の表面に付着したニッケル化合物を洗い落とすことができ、マグネシウム及びアルミニウムを含有する複合金属酸化物の前駆体にのみニッケルを担持することもできる。無機繊維上や無機バインダー上に堆積した余分なニッケル成分は、改質反応時の条件によって炭素析出の原因となりうる。そのため改質条件に合わせて余分なニッケル成分を水洗などにより取り除くこともできる。 The sheet-shaped molded body may be washed with water after the sheet-shaped molded body is immersed in an aqueous solution in which a nickel compound is dissolved. By washing with water, the nickel compound adhering to the surface of the sheet-like molded body can be washed away, and nickel can be supported only on the precursor of the composite metal oxide containing magnesium and aluminum. Excess nickel component deposited on the inorganic fiber or inorganic binder can cause carbon deposition depending on the conditions during the reforming reaction. Therefore, excess nickel components can be removed by washing or the like according to the reforming conditions.
　ニッケル化合物を溶解させた水溶液中に浸漬し、乾燥したシート状成形体を更に６００℃以上９５０℃以下で焼成してもよい（第二焼成）。焼成時の焼成雰囲気は、空気や不活性ガス（窒素ガス、アルゴンガス等）等が用いられるが、通常は空気が用いられる。第二焼成を行うことによってシート状成形体の表面に付着したニッケル化合物のアニオン成分（硝酸イオン、炭酸イオン、ハロゲンイオン他）を分解・除去することができ、その後の還元時におけるニッケル微粒子形成時への影響を防ぐ事が出来る。 The sheet-like molded body dipped in an aqueous solution in which a nickel compound is dissolved and dried may be further fired at 600 ° C. or more and 950 ° C. or less (second firing). Air, inert gas (nitrogen gas, argon gas, etc.), etc. are used for the baking atmosphere at the time of baking, but air is usually used. By performing the second firing, the anion components (nitrate ions, carbonate ions, halogen ions, etc.) of the nickel compounds adhering to the surface of the sheet-like molded body can be decomposed and removed, and during the subsequent reduction, nickel fine particles are formed Can be prevented.
　また、シート状成形体に抄き込むマグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子が、予めニッケルの金属又は金属酸化物を含む場合には、シート状成形体の焼成を一度だけ行って焼成したシート状成形体を得てもよく、また、更に前述のように、シート状成形体を第一焼成の後にニッケル化合物を溶解させた水溶液中に浸漬して、マグネシウム及びアルミニウムを含有する複合金属酸化物の前駆体により多くのニッケルを含有させ、更に第二焼成を行って焼成したシート状成形体を得てもよい。 In addition, when the layered double hydroxide particles containing magnesium and aluminum or the composite metal oxide particles containing magnesium and aluminum incorporated into the sheet-shaped molded body contain nickel metal or metal oxide in advance The sheet-shaped molded body may be fired only once to obtain a fired sheet-shaped molded body. Further, as described above, the sheet-shaped molded body is in an aqueous solution in which the nickel compound is dissolved after the first firing. It is possible to obtain a sheet-like molded body that is immersed in the substrate, contains a large amount of nickel in the precursor of the composite metal oxide containing magnesium and aluminum, and further baked by second baking.
　複合金属酸化物上に微粒子ニッケルを析出するためにニッケルを含む複合金属酸化物粒子が抄き込まれ、焼成したシート状成形体を７００℃以上９５０℃以下で加熱還元する。還元時の雰囲気は、水素を含んだガスなど還元雰囲気であれば特に限定されない。前記シート状成形体を加熱還元することにより粒子径が２０ｎｍ以下であるニッケル微粒子が担持されたマグネシウム及びアルミニウムを含有する複合金属酸化物を含むペーパー状触媒構造体を得ることができる。加熱還元温度が９５０℃より高い温度で加熱還元するとニッケル粒子の粒子サイズが大きくなり、ＢＥＴ比表面積は小さくなって、ガス改質効率が低下するため好ましくない。加熱還元温度が７００℃より低い場合にはニッケルが還元されず触媒としての特性が得られないので好ましくない。加熱還元温度は好ましくは８００℃～９５０℃である。 In order to deposit fine nickel particles on the composite metal oxide, composite metal oxide particles containing nickel are incorporated, and the fired sheet-like molded body is heated and reduced at 700 ° C. or more and 950 ° C. or less. The atmosphere during the reduction is not particularly limited as long as it is a reducing atmosphere such as a gas containing hydrogen. By heating and reducing the sheet-like molded body, a paper-like catalyst structure including a composite metal oxide containing magnesium and aluminum on which nickel fine particles having a particle diameter of 20 nm or less are supported can be obtained. Heat reduction at a temperature higher than 950 ° C. is not preferable because the particle size of the nickel particles increases, the BET specific surface area decreases, and the gas reforming efficiency decreases. When the heating reduction temperature is lower than 700 ° C., nickel is not reduced and the characteristics as a catalyst cannot be obtained, which is not preferable. The heating reduction temperature is preferably 800 ° C. to 950 ° C.
　また、加熱還元温度が９５０℃より高い場合には、無機繊維の結晶化が過度に進み、ペーパー状触媒体の機械的強度が低下するため好ましくない。 Further, when the heating reduction temperature is higher than 950 ° C., the crystallization of inorganic fibers proceeds excessively and the mechanical strength of the paper-like catalyst body is lowered, which is not preferable.
　本発明者らはペーパー状触媒構造体において、触媒となるニッケルが担持された種々の担持体と、ペーパー状触媒構造体中における触媒能劣化との関係について様々に検討した結果、ハイドロタルサイト様化合物をニッケルの担体とした場合、９５０℃以下で加熱処理を行うことで高い触媒特性を示すことを見出した。本発明のペーパー状触媒構造体を用い、実施例に記載の改質試験でのメタン転化率は、通常５０％以上、好ましくは６０％以上である。 As a result of various investigations on the relationship between various supports on which nickel serving as a catalyst is supported in the paper-like catalyst structure and deterioration of catalytic activity in the paper-like catalyst structure, the present inventors have found that hydrotalcite-like It has been found that when the compound is a nickel carrier, high catalytic properties are exhibited by heat treatment at 950 ° C. or lower. Using the paper-like catalyst structure of the present invention, the methane conversion rate in the reforming tests described in the examples is usually 50% or more, preferably 60% or more.
　更に、ペーパー状触媒構造体中において無機バインダーにより結着されて存在するハイドロタルサイト様化合物に対し、ニッケルイオンを含む水溶液中に浸漬後、９５０℃以下で加熱還元することにより、ペーパー状触媒構造体に含まれるニッケルは優先的に、マグネシウム及びアルミニウムを含有する複合金属酸化物上に平均粒子径が１～２０ｎｍのニッケル金属の超微粒子として生成し、８００℃以下の低温下での改質反応においてもバイオガスのドライリフォーミング時に高転化率が得られることを見出し本発明に至った。 Furthermore, the paper-like catalyst structure is obtained by immersing the hydrotalcite-like compound present in the paper-like catalyst structure bound by an inorganic binder in an aqueous solution containing nickel ions and then heating and reducing it at 950 ° C. or lower. Nickel contained in the body is preferentially produced as ultrafine particles of nickel metal having an average particle diameter of 1 to 20 nm on a composite metal oxide containing magnesium and aluminum, and reforming reaction at a low temperature of 800 ° C. or lower. In addition, the present inventors have found that a high conversion rate can be obtained during dry reforming of biogas.
　本発明者らはペーパー状触媒構造体において、触媒となるニッケルが担持されるマグネシウム及びアルミニウムを含有する複合金属酸化物の前駆体となるマグネシウム及びアルミニウムを含有する層状複水酸化物又はマグネシウム及びアルミニウムを含有する複合金属酸化物と、バイオガスのメタン転化率と耐炭素析出性についての関係を様々検討した結果、６００℃焼成後のＢＥＴ比表面積が１００ｍ２／ｇ以下のマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子をペーパー状触媒構造体中に抄き込み、９５０℃以下で加熱処理を行い、続いてニッケル微粒子を担持することで、バイオガスの改質反応において炭素析出が抑制される事を見出した。 In the paper-like catalyst structure, the inventors of the present invention have a layered double hydroxide or magnesium and aluminum containing magnesium and aluminum as precursors of a composite metal oxide containing magnesium and aluminum on which nickel as a catalyst is supported. As a result of various studies on the relationship between the composite metal oxide containing methane, the methane conversion rate of biogas and the carbon deposition resistance, it contains magnesium and aluminum having a BET specific surface area of not more than 100 m 2 / g after firing at 600 ° C. By laminating layered double hydroxide particles or composite metal oxide particles containing magnesium and aluminum into a paper-like catalyst structure, heat treatment at 950 ° C. or lower, and subsequently supporting nickel fine particles, It has been found that carbon deposition is suppressed in the gas reforming reaction.
　更に、ペーパー状触媒構造体中において無機バインダーにより結着されて存在するマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子に対し、ニッケルイオンを含む水溶液中に浸漬後、９５０℃以下で加熱還元することにより、ペーパー状触媒構造体に含まれるニッケルは優先的に、マグネシウム及びアルミニウムを含有する複合金属酸化物上に平均粒子径が１～２０ｎｍのニッケル金属の超微粒子として生成し、８００℃以下の低温下での改質反応においてもバイオガスの改質時に高メタン転化率が得られることを見出し本発明に至った。 Further, an aqueous solution containing nickel ions for layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum present in a paper-like catalyst structure bound by an inorganic binder The nickel contained in the paper-like catalyst structure is preferentially nickel having an average particle diameter of 1 to 20 nm on the composite metal oxide containing magnesium and aluminum by being heated and reduced at 950 ° C. or lower after being immersed therein. It has been found that a high methane conversion rate can be obtained at the time of biogas reforming even in a reforming reaction produced as ultrafine metal particles at a low temperature of 800 ° C. or lower.
　以下、実施例により本発明を更に詳細に説明するが、本発明は、その要旨を変更しない限り以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless the gist thereof is changed.
　無機繊維の長さ及び太さは、走査型電子顕微鏡（ＳＥＭ）（ＨＩＴＡＣＨＩ製　Ｓ－４８００型）で確認した。 The length and thickness of the inorganic fibers were confirmed with a scanning electron microscope (SEM) (HITACHI S-4800 type).
　スラリーに添加するマグネシウム及びアルミニウムを含有する層状複水酸化物粒子、又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子の平均粒子径は（走査透過電子顕微鏡（ＳＴＥＭ）（ＨＩＴＡＣＨＩ製　ＨＤ－２３００Ａ）で確認した。 The average particle diameter of the layered double hydroxide particles containing magnesium and aluminum added to the slurry, or the composite metal oxide particles containing magnesium and aluminum (scanning transmission electron microscope (STEM) (HITACHI HD-2300A)) confirmed.
　マグネシウム及びアルミニウムを含有する層状複水酸化物又はマグネシウム及びアルミニウムを含有する複合金属酸化物のＢＥＴ比表面積は（日本ベル製　ＢＥＬＳＯＰＥ－ｍｉｎｉ　ＩＩ）を用いて測定した値で示した。ＢＥＴ比表面積は、大気中で１０５℃で３時間乾燥させ室温まで冷却したものと、大気中６００℃で５時間焼成し室温まで冷却したものについて測定した。 The BET specific surface area of the layered double hydroxide containing magnesium and aluminum or the composite metal oxide containing magnesium and aluminum was indicated by a value measured using (BELSOPE-mini II manufactured by Nippon Bell). The BET specific surface area was measured for those dried in air at 105 ° C. for 3 hours and cooled to room temperature, and those fired in air at 600 ° C. for 5 hours and cooled to room temperature.
　マグネシウム及びアルミニウムを含有する層状複水酸化物、又はマグネシウム及びアルミニウムを含有する複合金属酸化物に含まれるマグネシウムとアルミニウムの比率は、ＩＣＰプラズマ発光分析装置（Ｔｈｅｒｍｏ　Ｆｉｓｈｅｒ製　ｉＣＡＰ－６５００ＤＵＯ）を用いて測定した値で示した。 The ratio of magnesium to aluminum contained in the layered double hydroxide containing magnesium and aluminum or the composite metal oxide containing magnesium and aluminum was measured using an ICP plasma emission spectrometer (iCAP-6500DUO manufactured by Thermo Fisher). It was shown by the value.
　ニッケル金属微粒子の平均粒子径は、ペーパー状触媒構造体を粗粉砕して走査透過型電子顕微鏡（ＳＴＥＭ）（ＨＩＴＡＣＨＩ製　ＨＤ－２３００Ａ））にて観察し、マグネシウム及びアルミニウムを含有する複合金属酸化物上に存在するニッケル金属微粒子５０個の平均値として算出した。 The average particle diameter of the nickel metal fine particles was observed by a scanning transmission electron microscope (STEM) (HD-2300A manufactured by HITACHI) after roughly pulverizing the paper-like catalyst structure, and a composite metal oxide containing magnesium and aluminum It calculated as an average value of 50 nickel metal fine particles existing above.
　ペーパー状触媒構造体に含まれるニッケルの量は、粉砕したペーパー状触媒構造体を四ホウ酸リチウムを用いた溶融法により測定サンプルを調製し、ＩＣＰプラズマ発光分析装置（Ｔｈｅｒｍｏ　Ｆｉｓｈｅｒ製　ｉＣＡＰ－６５００ＤＵＯ）を用いて測定した値で示した。 The amount of nickel contained in the paper-like catalyst structure is measured by preparing a measurement sample by pulverizing the pulverized paper-like catalyst structure using lithium tetraborate, an ICP plasma emission spectrometer (iCAP-6500DUO manufactured by Thermo Fisher). It showed by the value measured using.
　ペーパー状触媒構造体のＢＥＴ比表面積は、（日本ベル製　ＢＥＬＳＯＰＥ－ｍｉｎｉ　ＩＩ）を用いて測定した値で示した。 The BET specific surface area of the paper-like catalyst structure was indicated by a value measured using (BELSOPE-mini II, manufactured by Nippon Bell).
　ペーパー状触媒構造体の強度は、図１に示すように、ペーパー状触媒構造体を５０ｍｍ×１５ｍｍの短冊状に切断した試験片を、上下を３０ｍｍの間隔で５ｍｍ幅のつかみ部でチャッキングして、ＩＭＡＤＡ製引っ張り試験機で引っ張り速度１００ｍｍ／ｍｉｎで引っ張り、試験片が断裂するまでの最大荷重で表した。 As shown in FIG. 1, the strength of the paper-like catalyst structure is obtained by chucking a test piece obtained by cutting the paper-like catalyst structure into a strip of 50 mm × 15 mm with a gripping portion having a width of 5 mm at intervals of 30 mm. The maximum load until the specimen was torn and was pulled with an IMADA tensile tester at a pulling rate of 100 mm / min.
使用した原料
１．無機繊維
・非晶質シリカ－アルミナ繊維（ＩＢＩ　ＷＯＯＬ（登録商標）　Ｊ－１５、イビデン（株）製）平均繊維径：２．３μｍ　平均繊維長３８μｍ
２．酸化物ゾル（無機バインダー）
・ジルコニアゾル（第一稀元素化学工業製）
・セリアゾル（第一稀元素化学工業製）
・イットリア安定化ジルコニアゾル（日産化学工業（株）製）
３．イオン性ポリマー
いずれのポリマーも０．２ｗｔ％の水溶液に調製して用いた。
・ＰＤＡＤＭＡＣ（ｐｏｌｙｄｉａｌｌｙｌｄｉｍｅｔｈｙｌａｍｍｏｎｉｕｍ　ｃｈｌｏｒｉｄｅ、Ｓｉｇｍａ　－Ａｌｄｒｉｃｈ，　Ｌｔｄ．製）
　　カチオン性
　　分子量：約３×１０５
　　電荷密度：５．５　ｍｅｑ／ｇ
・ポリアクリルアミド（富士化水工業（株）製）
　　アニオン性
　　分子量：約１．２×１０７
　　電荷密度：０．８３～１．３６　ｍｅｑ／ｇ Used raw materials Inorganic fiber / Amorphous silica-alumina fiber (IBI WOOL (registered trademark) J-15, manufactured by Ibiden Co., Ltd.) Average fiber diameter: 2.3 μm Average fiber length: 38 μm
2. Oxide sol (inorganic binder)
・ Zirconia sol (manufactured by Daiichi rare element chemical industry)
・ Ceria sol (Daiichi Rare Element Chemical Industries)
・ Yttria stabilized zirconia sol (manufactured by Nissan Chemical Industries, Ltd.)
3. All of the ionic polymers were prepared in 0.2 wt% aqueous solutions.
PDADMAC (manufactured by polydyldimethylammonium chloride, Sigma-Aldrich, Ltd.)
Cationic molecular weight: about 3 × 10 5
Charge density: 5.5 meq / g
・ Polyacrylamide (Fujikamizu Co., Ltd.)
Anionic molecular weight: about 1.2 × 10 7
Charge density: 0.83-1.36 meq / g
　実施例１：
　無機繊維としてＩＢＩ　ＷＯＯＬ　Ｊ－１５（５ｇ）と６００ｍＬの蒸留水をミキサーで約３分混合した。次いで、３Ｌのプラスチックカップにマグネチックスターラーチップ、ハイドロタルサイト（平均粒子径：１５０ｎｍ、Ｍｇ／Ａｌ比：３）１ｇと先の混合処理したＩＢＩ　ＷＯＯＬのスラリーを投入し、全体で１．５Ｌの体積になるよう蒸留水を加えて約３０秒撹拌した。スターラーで攪拌しながらカチオン性ポリマーであるＰＤＡＤＭＡＣの水溶液（０．２ｗｔ％）を１５．０ｇ投入し、約３分間撹拌した。 Example 1:
As inorganic fibers, IBI WOOL J-15 (5 g) and 600 mL of distilled water were mixed with a mixer for about 3 minutes. Next, a magnetic stirrer chip, 1 g of hydrotalcite (average particle size: 150 nm, Mg / Al ratio: 3) and the previously mixed IBI WOOL slurry were put into a 3 L plastic cup, and 1.5 L of the total was added. Distilled water was added to make the volume, and the mixture was stirred for about 30 seconds. While stirring with a stirrer, 15.0 g of an aqueous solution (0.2 wt%) of PDADMAC, which is a cationic polymer, was added and stirred for about 3 minutes.
　次いで、焼成後に無機バインダーとして機能するジルコニアゾル（固形分濃度２０ｗｔ％）を２．５ｇ加え約３０秒間撹拌した。次にアニオン性ポリマーであるポリアクリルアミドポリマーの水溶液（０．２ｗｔ％）を１６．２５ｇ加え約３分間撹拌した。なお、アニオン性ポリマーを投入したときに、無機繊維等が凝集して玉状になる。 Next, 2.5 g of zirconia sol (solid content concentration 20 wt%) functioning as an inorganic binder after firing was added and stirred for about 30 seconds. Next, 16.25 g of an aqueous solution (0.2 wt%) of polyacrylamide polymer which is an anionic polymer was added and stirred for about 3 minutes. In addition, when an anionic polymer is thrown in, an inorganic fiber etc. aggregate and it becomes a ball shape.
　次に、叩解処理したパルプ（１０ｗｔ％）２．５ｇを解繊してスラリーに加え、約３分攪拌した。 Next, 2.5 g of beaten pulp (10 wt%) was defibrated, added to the slurry, and stirred for about 3 minutes.
　得られたスラリーを市販の抄紙装置（熊谷理機工業株式会社製）に注ぎ込み、直径１６０ｍｍの円形のろ過用金属網（２００メッシュ）に懸濁混合物を脱水により堆積させた。形成された堆積物をメッシュから剥がし取り、３５０ｋＰａで３分プレスし、１０５℃で２時間乾燥させることで、シート状成形体を得た。 The obtained slurry was poured into a commercially available papermaking apparatus (manufactured by Kumagai Riki Kogyo Co., Ltd.), and the suspension mixture was deposited on a circular metal mesh (200 mesh) having a diameter of 160 mm by dehydration. The formed deposit was peeled off from the mesh, pressed at 350 kPa for 3 minutes, and dried at 105 ° C. for 2 hours to obtain a sheet-like molded body.
　得られたシート状成形体を大気雰囲気下、８００℃、５時間の第一焼成をした。第一焼成後のシート状成形体を走査型電子顕微鏡（ＳＥＭ）（ＨＩＴＡＣＨＩ製Ｓ－４８００型）で確認したところ、無機繊維上にハイドロタルサイトの形骸を有する板状の微粒子が重なり合うようにして付着している様子が観察できた。 The obtained sheet-like molded body was first baked at 800 ° C. for 5 hours in an air atmosphere. When the sheet-like molded body after the first firing was confirmed with a scanning electron microscope (SEM) (HITACHI S-4800 type), plate-like fine particles having a hydrotalcite structure overlapped on inorganic fibers. The state of adhesion could be observed.
　続いて、第一焼成後のシート状成形体を０．１ｍｏｌ／Ｌの硝酸ニッケル水溶液中に１時間浸漬した後、１０５℃で３時間乾燥し、８００℃、５時間の第二焼成をした。 Subsequently, the sheet-like molded body after the first firing was immersed in a 0.1 mol / L nickel nitrate aqueous solution for 1 hour, dried at 105 ° C. for 3 hours, and then subjected to second firing at 800 ° C. for 5 hours.
　次に、第二焼成後のシート状成形体を５％　Ｈ２／Ｎ２中、８００℃において１５時間還元処理を行い、厚さ約１ｍｍのペーパー状触媒構造体を得た。得られたペーパー状触媒構造体を走査型電子顕微鏡（ＳＥＭ）（ＨＩＴＡＣＨＩ製Ｓ－４８００型）で確認したところ、無機繊維上に凹凸のある塊状物が付着している様子が観察できた。 Next, the sheet-like molded body after the second baking was subjected to a reduction treatment in 5% H 2 / N 2 at 800 ° C. for 15 hours to obtain a paper-like catalyst structure having a thickness of about 1 mm. When the obtained paper-like catalyst structure was confirmed with a scanning electron microscope (SEM) (HITACHI S-4800 type), it was possible to observe that uneven lumps adhered to the inorganic fibers.
　実施例２：
　ハイドロタルサイトを表１に記載のものに変えた以外は実施例１と同じ方法で調製しペーパー状触媒構造体を得た。 Example 2:
A paper-like catalyst structure was obtained in the same manner as in Example 1 except that the hydrotalcite was changed to that shown in Table 1.
　実施例３：
　ハイドロタルサイトを表１に記載のものに変えた以外は実施例１と同じ方法で調製しペーパー状触媒構造体を得た。 Example 3:
A paper-like catalyst structure was obtained in the same manner as in Example 1 except that the hydrotalcite was changed to that shown in Table 1.
　実施例４：
　無機繊維としてＩＢＩ　ＷＯＯＬ　Ｊ－１５（５ｇ）と６００ｍＬの蒸留水をミキサーで約３分混合した。次いで、３Ｌのプラスチックカップにマグネチックスターラーチップ、ハイドロタルサイト（平均粒子径：１５０ｎｍ、Ｍｇ／Ａｌ比：３）１ｇと、先の混合処理したＩＢＩ　ＷＯＯＬのスラリーを投入し、全体で１．５Ｌの体積になるよう蒸留水を加えて約３０秒撹拌した。スターラーで攪拌しながらカチオン性ポリマーであるＰＤＡＤＭＡＣの水溶液（０．２ｗｔ％）を１５．０ｇ投入し、約３分間撹拌した。 Example 4:
As inorganic fibers, IBI WOOL J-15 (5 g) and 600 mL of distilled water were mixed with a mixer for about 3 minutes. Next, the magnetic stirrer chip, 1 g of hydrotalcite (average particle size: 150 nm, Mg / Al ratio: 3) and the previously mixed IBI WOOL slurry were put into a 3 L plastic cup, and 1.5 L in total. Distilled water was added so that the volume of the mixture became about 30 seconds, followed by stirring for about 30 seconds. While stirring with a stirrer, 15.0 g of an aqueous solution (0.2 wt%) of PDADMAC, which is a cationic polymer, was added and stirred for about 3 minutes.
　次いで、焼成後に無機バインダーとして機能するセリアゾル（固形分濃度３０ｗｔ％）を１．６５ｇ加え約３０秒間撹拌した。次にアニオン性ポリマーであるポリアクリルアミドポリマーの水溶液（０．２ｗｔ％）を１６．２５ｇ加え約３分間撹拌した。なお、アニオン性ポリマーを投入したときに、無機繊維等が凝集して玉状になる。 Next, 1.65 g of ceria sol (solid content concentration 30 wt%) functioning as an inorganic binder after firing was added and stirred for about 30 seconds. Next, 16.25 g of an aqueous solution (0.2 wt%) of polyacrylamide polymer which is an anionic polymer was added and stirred for about 3 minutes. In addition, when an anionic polymer is thrown in, an inorganic fiber etc. aggregate and it becomes a ball shape.
　次に、叩解処理したパルプ（１０ｗｔ％）２．５ｇを解繊してスラリーに加え、約３分攪拌した。 Next, 2.5 g of beaten pulp (10 wt%) was defibrated, added to the slurry, and stirred for about 3 minutes.
　得られたスラリーを市販の抄紙装置（熊谷理機工業株式会社製）に注ぎ込み、１６０ｍｍの円形のろ過用金属網（２００メッシュ）に懸濁混合物を脱水により堆積させた。形成された堆積物をメッシュから剥がし取り、３５０ｋＰａで３分プレスし、１０５℃で２時間乾燥させることで、シート状成形体を得た。 The obtained slurry was poured into a commercially available paper making apparatus (manufactured by Kumagai Riki Kogyo Co., Ltd.), and the suspension mixture was deposited on a 160 mm circular metal mesh for filtration (200 mesh) by dehydration. The formed deposit was peeled off from the mesh, pressed at 350 kPa for 3 minutes, and dried at 105 ° C. for 2 hours to obtain a sheet-like molded body.
　得られたシート状成形体を大気雰囲気下、８００℃、５時間の第一焼成をした。続いてシート状成形体を０．１ｍｏｌ／Ｌの硝酸ニッケル水溶液中に１時間浸漬した後、１０５℃で３時間乾燥し、８００℃、５時間の第二焼成をした。５％Ｈ２／Ｎ２中、８００℃において１５時間還元処理を行い、厚さ約１ｍｍのペーパー状触媒構造体を得た。 The obtained sheet-like molded body was first baked at 800 ° C. for 5 hours in an air atmosphere. Subsequently, the sheet-like molded body was immersed in a 0.1 mol / L nickel nitrate aqueous solution for 1 hour, dried at 105 ° C. for 3 hours, and then subjected to second baking at 800 ° C. for 5 hours. A reduction treatment was performed for 15 hours at 800 ° C. in 5% H 2 / N 2 to obtain a paper-like catalyst structure having a thickness of about 1 mm.
　比較例１：
　５％Ｈ２／Ｎ２中、１０００℃において１時間還元処理を行った以外は実施例１と同じ処理を行って、厚さ約１ｍｍのペーパー状触媒構造体を得た。 Comparative Example 1:
A paper-like catalyst structure having a thickness of about 1 mm was obtained by carrying out the same treatment as in Example 1 except that the reduction treatment was carried out in 5% H 2 / N 2 at 1000 ° C. for 1 hour.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～４及び比較例１で得られたペーパー状触媒構造体の分析結果を表２に示す。実施例のペーパー状触媒構造体は機械的強度を備えたものであって、ニッケル金属微粒子の平均粒子径は２０ｎｍ以下の微細なものであった。一方、比較例１のペーパー状触媒構造体は、高温での還元を行ったために脆くなっており、ニッケル金属微粒子のサイズも大きなものとなっていた。 Table 2 shows the analysis results of the paper-like catalyst structures obtained in Examples 1 to 4 and Comparative Example 1. The paper-like catalyst structures of the examples had mechanical strength, and the nickel metal fine particles had a fine average particle size of 20 nm or less. On the other hand, the paper-like catalyst structure of Comparative Example 1 was brittle because of the reduction at high temperature, and the size of the nickel metal fine particles was large.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　改質試験：
　メタンガスと炭酸ガスを混合した疑似バイオガス及びキャリアーガス（測定時の基準ガス）として窒素ガスを用い改質試験を２時間行った。 Modification test:
A reforming test was conducted for 2 hours using nitrogen gas as a pseudo biogas mixed with methane gas and carbon dioxide gas and carrier gas (reference gas at the time of measurement).
　実施例１～４及び比較例１により作製したペーパー状触媒構造体（直径２０ｍｍ、内径６ｍｍの円環形状に切断）を二枚重ね、円環の穴に丸棒状の支持体を通して、内径直径２０ｍｍの円筒形の改質試験機（図２）に組み込んで、ガス流量を、メタンガス：炭酸ガス：窒素ガス＝４０ｃｃ／ｍｉｎ：４０ｃｃ／ｍｉｎ：４０ｃｃ／ｍｉｎとし、反応温度は７５０℃として改質試験を行った。 Two paper-like catalyst structures (cut into an annular shape with a diameter of 20 mm and an inner diameter of 6 mm) prepared in Examples 1 to 4 and Comparative Example 1 were stacked, and a circular rod-like support was passed through the hole of the annular shape, and a cylinder with an inner diameter of 20 mm. The reforming test was conducted with a gas flow rate of methane gas: carbon dioxide gas: nitrogen gas = 40 cc / min: 40 cc / min: 40 cc / min and a reaction temperature of 750 ° C. It was.
　実施例のペーパー状触媒構造体を用いた改質試験ではいずれも高いメタン転化率を示した。一方、比較例１のペーパー状触媒構造体を用いた場合には、メタン転化率が低かった。比較例１のペーパー状触媒構造体は実施例に比べてニッケル金属微粒子のサイズが大きく、ＢＥＴ比表面積も小さいため、炭化水素を含有するガスがニッケル微粒子に接触する面積が小さくなってメタン転化率が上がらなかったものと考えている。 In the reforming tests using the paper-like catalyst structures of the examples, all showed high methane conversion. On the other hand, when the paper-like catalyst structure of Comparative Example 1 was used, the methane conversion rate was low. Since the paper-like catalyst structure of Comparative Example 1 has a larger nickel metal fine particle size and a smaller BET specific surface area than the Examples, the area in which the hydrocarbon-containing gas contacts the nickel fine particle is reduced, and the methane conversion rate I think that it did not go up.
　実施例５：
　無機バインダーをイットリア安定化ジルコニアゾル（固形分濃度３０ｗｔ％）１．６７ｇに変えた以外は実施例１と同じ方法で調製しペーパー状触媒構造体を得た。 Example 5:
A paper-like catalyst structure was obtained in the same manner as in Example 1 except that the inorganic binder was changed to 1.67 g of yttria-stabilized zirconia sol (solid content concentration 30 wt%).
　実施例６：
　無機バインダーをイットリア安定化ジルコニアゾル（固形分濃度３０ｗｔ％）１．６７ｇに変えた以外は実施例２と同じ方法で調製し、ペーパー状触媒構造体を得た。 Example 6:
A paper-like catalyst structure was obtained in the same manner as in Example 2 except that the inorganic binder was changed to 1.67 g of yttria-stabilized zirconia sol (solid content concentration 30 wt%).
　実施例７：
　無機バインダーをセリアゾル（固形分濃度３０ｗｔ％）１．６７ｇに変えた以外は実施例２と同じ方法で調製し、ペーパー状触媒構造体を得た。 Example 7:
A paper-like catalyst structure was obtained in the same manner as in Example 2 except that the inorganic binder was changed to 1.67 g of ceria sol (solid content concentration 30 wt%).
　実施例８：
　無機バインダーをイットリア安定化ジルコニアゾル（固形分濃度３０ｗｔ％）１．６７ｇに変えた以外は実施例３と同じ方法で調製しペーパー状触媒構造体を得た。 Example 8:
A paper-like catalyst structure was obtained in the same manner as in Example 3 except that the inorganic binder was changed to 1.67 g of yttria-stabilized zirconia sol (solid content concentration 30 wt%).
　実施例９：
　無機バインダーをセリアゾル（固形分濃度３０ｗｔ％）１．６７ｇに変えた以外は実施例３と同じ方法で調製しペーパー状触媒構造体を得た。 Example 9:
A paper-like catalyst structure was obtained in the same manner as in Example 3 except that the inorganic binder was changed to 1.67 g of ceria sol (solid content concentration 30 wt%).
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　実施例５～９で得られたペーパー状触媒構造体の分析結果を表４に示す。 Table 4 shows the analysis results of the paper-like catalyst structures obtained in Examples 5 to 9.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　改質試験：
　メタンガスと炭酸ガスを混合した疑似バイオガス及びキャリアーガス（測定時の基準ガス）として窒素ガスを用い改質試験を２時間行った。 Modification test:
A reforming test was conducted for 2 hours using nitrogen gas as a pseudo biogas mixed with methane gas and carbon dioxide gas and carrier gas (reference gas at the time of measurement).
　実施例５～９により作製したペーパー状触媒構造体（直径２０ｍｍ、内径６ｍｍの円環形状に切断）を二枚重ね、円環の穴に丸棒状の支持体を通して、内径直径２０ｍｍの円筒形の改質試験機（図２）に組み込んで、ガス流量を、メタンガス：炭酸ガス：窒素ガス＝４０ｃｃ／ｍｉｎ：４０ｃｃ／ｍｉｎ：４０ｃｃ／ｍｉｎとし、反応温度は７５０℃として改質試験を行った。 Two paper-like catalyst structures (cut into a circular shape with a diameter of 20 mm and an internal diameter of 6 mm) produced in Examples 5 to 9 were stacked, and a round rod-shaped support was passed through the hole of the circular ring to reform a cylindrical shape with an internal diameter of 20 mm. The reforming test was carried out with the gas flow rate set to methane gas: carbon dioxide gas: nitrogen gas = 40 cc / min: 40 cc / min: 40 cc / min and the reaction temperature was 750 ° C. by incorporating in a tester (FIG. 2).
　実施例１～９で用いた層状複水酸化物又は複合金属酸化物の特徴と、得られたペーパー状触媒構造体の炭素析出についての分析結果を表５に示す。 Table 5 shows the characteristics of the layered double hydroxide or composite metal oxide used in Examples 1 to 9 and the analysis results of carbon deposition of the obtained paper-like catalyst structure.
　炭素析出性の評価は、改質試験後のペーパー状触媒構造体の観察によって行った。表５には、次の基準で炭素析出性を分類した。
微量：改質試験の前後でほとんど触媒構造体の表面の色に変化が見られず、触媒構造体の表面の１０％未満に炭素の析出が認められる。
少ない：触媒構造体の表面の５０％未満が炭素の析出により黒色化している。
多い：触媒構造体の表面の５０％以上が炭素の析出により黒色化している。 The carbon precipitation was evaluated by observing the paper-like catalyst structure after the reforming test. Table 5 classifies the carbon deposition properties according to the following criteria.
Trace amount: Almost no change in the color of the surface of the catalyst structure was observed before and after the reforming test, and carbon deposition was observed on less than 10% of the surface of the catalyst structure.
Less: Less than 50% of the surface of the catalyst structure is blackened due to carbon deposition.
Many: 50% or more of the surface of the catalyst structure is blackened by carbon deposition.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　実施例１、２及び４～７のペーパー状触媒構造体を用いた改質試験ではいずれも良好なメタン転化率を示し、改質試験後のペーパー状触媒構造体には僅かしか炭素析出が確認されなかった。６００℃焼成後のＢＥＴ比表面積が１００ｍ２／ｇを超える層状復水酸化物を用いた実施例３、８及び９のペーパー状触媒構造体を用いた場合には、メタン転化率は良好であったが、改質試験後のペーパー状触媒構造体には顕著な炭素析出が確認された。 In the reforming tests using the paper-like catalyst structures of Examples 1, 2, and 4 to 7, all showed good methane conversion, and a slight amount of carbon deposition was confirmed in the paper-like catalyst structures after the reforming test. Was not. When the paper-like catalyst structures of Examples 3, 8 and 9 using a layered condensed hydroxide having a BET specific surface area of more than 100 m 2 / g after calcination at 600 ° C. were used, the methane conversion was good. However, remarkable carbon deposition was confirmed in the paper-like catalyst structure after the reforming test.
　本発明に係るペーパー状触媒構造体は、水素を効率よく製造でき、機械的強度も備えているため取扱いが容易である。また、低温での改質反応においても水素を効率よく製造できるため、バイオガスのドライリフォーミング等に適している。 The paper-like catalyst structure according to the present invention is easy to handle because it can efficiently produce hydrogen and has mechanical strength. Further, hydrogen can be efficiently produced even in a reforming reaction at a low temperature, which is suitable for dry reforming of biogas.
　１：試験片
　２：チャッキング
　１１：ペーパー状触媒構造体
　１２：反応管
　１３：加熱装置
　１４：支持体
　ＧＣ：ガスクロマトグラフ 1: Test piece 2: Chucking 11: Paper-like catalyst structure 12: Reaction tube 13: Heating device 14: Support GC: Gas chromatograph

Claims (6)

  1. 　無機繊維と平均粒子径が１～２０ｎｍであるニッケル金属微粒子が担持されたマグネシウム及びアルミニウムを含有する複合金属酸化物とを含む触媒シート。 A catalyst sheet comprising inorganic fibers and a composite metal oxide containing magnesium and aluminum on which nickel metal fine particles having an average particle diameter of 1 to 20 nm are supported.
  2. 　無機繊維がアルミナ、シリカ、ジルコニア、セリアから選ばれる一種以上を含む繊維である請求項１記載の触媒シート。 The catalyst sheet according to claim 1, wherein the inorganic fiber is a fiber containing at least one selected from alumina, silica, zirconia, and ceria.
  3. 　無機繊維が低結晶性繊維を含む請求項１又は２に記載の触媒シート。 The catalyst sheet according to claim 1 or 2, wherein the inorganic fibers include low crystalline fibers.
  4. 　無機繊維、無機バインダー並びにマグネシウム及びアルミニウムを含有する層状複水酸化物粒子又はマグネシウム及びアルミニウムを含有する複合金属酸化物粒子を含むスラリーを湿式抄紙法によってシート状成形体とし、該成形体を５００℃以上９５０℃以下の温度で焼成後、ニッケル化合物を溶解した水溶液に浸漬し、乾燥後、７００℃以上９５０℃以下の温度で加熱還元することを特徴とする請求項１～３のいずれかに記載の触媒シートの製造方法。 Slurry containing inorganic fiber, inorganic binder and layered double hydroxide particles containing magnesium and aluminum or composite metal oxide particles containing magnesium and aluminum is formed into a sheet-like formed body by a wet papermaking method, and the formed body is heated to 500 ° C. 4. After firing at a temperature of 950 ° C. or lower, dipping in an aqueous solution in which a nickel compound is dissolved, drying, and then heat-reducing at a temperature of 700 ° C. or higher and 950 ° C. or lower. The manufacturing method of the catalyst sheet | seat.
  5. 　無機繊維、無機バインダー並びにマグネシウム、アルミニウム及びニッケルを含有する層状複水酸化物粒子又はマグネシウム、アルミニウム及びニッケルを含有する複合金属酸化物粒子を含むスラリーを湿式抄紙法によってシート状成形体とし、該成形体を５００℃以上９５０℃以下の温度で焼成、続いて７００℃以上９５０℃以下の温度で加熱還元することを特徴とする請求項１～３のいずれかに記載の触媒シートの製造方法。 Slurry containing inorganic fibers, inorganic binders and layered double hydroxide particles containing magnesium, aluminum and nickel or composite metal oxide particles containing magnesium, aluminum and nickel is formed into a sheet-like molded body by a wet papermaking method, and the molding is performed. The method for producing a catalyst sheet according to any one of claims 1 to 3, wherein the body is calcined at a temperature of 500 ° C or higher and 950 ° C or lower, and subsequently heated and reduced at a temperature of 700 ° C or higher and 950 ° C or lower.
  6. 　６００℃で５時間焼成した後のＢＥＴ比表面積が１００ｍ２／ｇ以下になる層状複水酸化物粒子又は複合金属酸化物粒子を用いる請求項４又は５に記載の触媒シートの製造方法。 The method for producing a catalyst sheet according to claim 4 or 5, wherein layered double hydroxide particles or composite metal oxide particles having a BET specific surface area of 100 m 2 / g or less after calcination at 600 ° C for 5 hours are used.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016185528A (en) * 2015-03-27 2016-10-27 戸田工業株式会社 Manufacturing method of paper-like catalyst structure for hydrogen production
JP2016185529A (en) * 2015-03-27 2016-10-27 戸田工業株式会社 Paper-like catalyst precursor for hydrogen production, manufacturing method thereof and paper-like catalyst structure for hydrogen production
CN107442119A (en) * 2017-08-10 2017-12-08 石家庄铁道大学 A kind of cerium oxide/zirconium oxide paper mold catalyst and preparation method thereof
JP2018034081A (en) * 2016-08-29 2018-03-08 国立大学法人九州大学 Paper-like catalyst and method for producing the same, paper-like catalyst arrangement, and hydrocarbon modifying method
CN111682228A (en) * 2020-07-06 2020-09-18 山东交通学院 Preparation method of diffusion layer with catalysis promoting function

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62114650A (en) * 1985-11-12 1987-05-26 Nippon Shokubai Kagaku Kogyo Co Ltd Combustion catalyst body
JPH06134307A (en) * 1992-10-27 1994-05-17 Matsushita Electric Ind Co Ltd Ceramic sheet with catalyst and its production
JP2003225566A (en) * 2002-02-01 2003-08-12 Hiroshima Industrial Promotion Organization Catalyst for decomposing hydrocarbon and production method therefor
JP2006061760A (en) * 2004-08-24 2006-03-09 Toda Kogyo Corp Catalyst for cracking of hydrocarbon and method of manufacturing hydrogen using it
JP2006110399A (en) * 2004-10-12 2006-04-27 Hitachi Zosen Corp Steam reforming catalyst
JP2011092825A (en) * 2009-10-28 2011-05-12 F C C:Kk Paper catalyst and method of manufacturing the same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62114650A (en) * 1985-11-12 1987-05-26 Nippon Shokubai Kagaku Kogyo Co Ltd Combustion catalyst body
JPH06134307A (en) * 1992-10-27 1994-05-17 Matsushita Electric Ind Co Ltd Ceramic sheet with catalyst and its production
JP2003225566A (en) * 2002-02-01 2003-08-12 Hiroshima Industrial Promotion Organization Catalyst for decomposing hydrocarbon and production method therefor
JP2006061760A (en) * 2004-08-24 2006-03-09 Toda Kogyo Corp Catalyst for cracking of hydrocarbon and method of manufacturing hydrogen using it
JP2006110399A (en) * 2004-10-12 2006-04-27 Hitachi Zosen Corp Steam reforming catalyst
JP2011092825A (en) * 2009-10-28 2011-05-12 F C C:Kk Paper catalyst and method of manufacturing the same

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
YUSUKE SHIRATORI ET AL.: "Paper-structured catalyst for the steam reforming of biodiesel fuel", INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, vol. 38, 17 July 2013 (2013-07-17), pages 11278 - 11287 *
YUSUKE SHIRATORI ET AL.: "Study on paper- structured catalyst for direct internal reforming SOFC fueled by the mixture of CH 4 and CO2", INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, vol. 38, pages 10542 - 10551 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016185528A (en) * 2015-03-27 2016-10-27 戸田工業株式会社 Manufacturing method of paper-like catalyst structure for hydrogen production
JP2016185529A (en) * 2015-03-27 2016-10-27 戸田工業株式会社 Paper-like catalyst precursor for hydrogen production, manufacturing method thereof and paper-like catalyst structure for hydrogen production
JP2018034081A (en) * 2016-08-29 2018-03-08 国立大学法人九州大学 Paper-like catalyst and method for producing the same, paper-like catalyst arrangement, and hydrocarbon modifying method
CN107442119A (en) * 2017-08-10 2017-12-08 石家庄铁道大学 A kind of cerium oxide/zirconium oxide paper mold catalyst and preparation method thereof
CN107442119B (en) * 2017-08-10 2019-10-29 石家庄铁道大学 A kind of cerium oxide/zirconium oxide paper mold catalyst and preparation method thereof
CN111682228A (en) * 2020-07-06 2020-09-18 山东交通学院 Preparation method of diffusion layer with catalysis promoting function

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