JP2005046808A - Catalyst for generating hydrogen - Google Patents
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- JP2005046808A JP2005046808A JP2003284042A JP2003284042A JP2005046808A JP 2005046808 A JP2005046808 A JP 2005046808A JP 2003284042 A JP2003284042 A JP 2003284042A JP 2003284042 A JP2003284042 A JP 2003284042A JP 2005046808 A JP2005046808 A JP 2005046808A
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- composite oxide
- hydrogen
- fuel
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- hydrogen generation
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 98
- 239000001257 hydrogen Substances 0.000 title claims abstract description 98
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 98
- 239000003054 catalyst Substances 0.000 title claims abstract description 70
- 239000000446 fuel Substances 0.000 claims abstract description 49
- 239000007789 gas Substances 0.000 claims abstract description 46
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000001301 oxygen Substances 0.000 claims abstract description 35
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 35
- 206010021143 Hypoxia Diseases 0.000 claims abstract description 14
- 238000000629 steam reforming Methods 0.000 claims abstract description 13
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 12
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 11
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 11
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims abstract description 11
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 11
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 11
- 229910052747 lanthanoid Inorganic materials 0.000 claims abstract description 11
- 150000002602 lanthanoids Chemical class 0.000 claims abstract description 11
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 11
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052706 scandium Inorganic materials 0.000 claims abstract description 10
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000002131 composite material Substances 0.000 claims description 121
- 238000006243 chemical reaction Methods 0.000 claims description 33
- 239000000126 substance Substances 0.000 claims description 28
- 229910000510 noble metal Inorganic materials 0.000 claims description 26
- 238000012546 transfer Methods 0.000 claims description 21
- 238000002407 reforming Methods 0.000 claims description 17
- 238000004519 manufacturing process Methods 0.000 claims description 14
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 6
- 230000003647 oxidation Effects 0.000 abstract description 4
- 238000007254 oxidation reaction Methods 0.000 abstract description 4
- 150000001340 alkali metals Chemical class 0.000 abstract description 2
- 150000001342 alkaline earth metals Chemical class 0.000 abstract description 2
- 239000000843 powder Substances 0.000 description 93
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 49
- 239000002245 particle Substances 0.000 description 41
- 238000005259 measurement Methods 0.000 description 32
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 28
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 24
- 238000000034 method Methods 0.000 description 21
- 239000011163 secondary particle Substances 0.000 description 20
- 239000010419 fine particle Substances 0.000 description 19
- 239000011572 manganese Substances 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- 229910052697 platinum Inorganic materials 0.000 description 14
- 230000005540 biological transmission Effects 0.000 description 11
- 238000004817 gas chromatography Methods 0.000 description 11
- 239000000203 mixture Substances 0.000 description 11
- 239000010453 quartz Substances 0.000 description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 11
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 10
- 230000003197 catalytic effect Effects 0.000 description 9
- 238000010304 firing Methods 0.000 description 9
- 229910052746 lanthanum Inorganic materials 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- UYXRCZUOJAYSQR-UHFFFAOYSA-N nitric acid;platinum Chemical compound [Pt].O[N+]([O-])=O UYXRCZUOJAYSQR-UHFFFAOYSA-N 0.000 description 9
- 238000000149 argon plasma sintering Methods 0.000 description 8
- 238000012790 confirmation Methods 0.000 description 8
- 238000009826 distribution Methods 0.000 description 8
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 8
- 238000000634 powder X-ray diffraction Methods 0.000 description 8
- 238000001354 calcination Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 7
- 229940093474 manganese carbonate Drugs 0.000 description 7
- 235000006748 manganese carbonate Nutrition 0.000 description 7
- 239000011656 manganese carbonate Substances 0.000 description 7
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 7
- XMWCXZJXESXBBY-UHFFFAOYSA-L manganese(ii) carbonate Chemical compound [Mn+2].[O-]C([O-])=O XMWCXZJXESXBBY-UHFFFAOYSA-L 0.000 description 7
- 239000010948 rhodium Substances 0.000 description 7
- 229910052712 strontium Inorganic materials 0.000 description 7
- 238000004448 titration Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- NPFOYSMITVOQOS-UHFFFAOYSA-K iron(III) citrate Chemical compound [Fe+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NPFOYSMITVOQOS-UHFFFAOYSA-K 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 5
- 239000002737 fuel gas Substances 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 229910052788 barium Inorganic materials 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910052763 palladium Inorganic materials 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- 229910052703 rhodium Inorganic materials 0.000 description 4
- 229910052707 ruthenium Inorganic materials 0.000 description 4
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 150000001768 cations Chemical class 0.000 description 3
- 239000007809 chemical reaction catalyst Substances 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 238000000691 measurement method Methods 0.000 description 3
- 229910052700 potassium Inorganic materials 0.000 description 3
- 239000010970 precious metal Substances 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 108091006149 Electron carriers Proteins 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 229910052792 caesium Inorganic materials 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000004868 gas analysis Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000005518 polymer electrolyte Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000012552 review Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 238000003746 solid phase reaction Methods 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 229910052730 francium Inorganic materials 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- SXUZODOWIKVCDO-UHFFFAOYSA-N nitric acid;rhodium Chemical compound [Rh].O[N+]([O-])=O SXUZODOWIKVCDO-UHFFFAOYSA-N 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- -1 platinum group metals Chemical class 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 229910052705 radium Inorganic materials 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000006057 reforming reaction Methods 0.000 description 1
- 229910052701 rubidium Inorganic materials 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- 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
Abstract
Description
本発明は、少なくとも水蒸気改質反応を用いて燃料改質を行い、水素ガスを得るための燃料改質触媒である水素生成触媒、および該触媒を用いた燃料改質器に関する。 The present invention relates to a hydrogen generation catalyst that is a fuel reforming catalyst for performing hydrogen reforming using at least a steam reforming reaction to obtain hydrogen gas, and a fuel reformer using the catalyst.
固体高分子型燃料電池は、水素と酸素を燃料として電気エネルギーを取り出す電池であり、高い出力密度、低温での動作、排気ガスに有害物質をほとんど含まないといった、特長を持ち合わせていながら、そのサイズや形状を、定置型、車載型などに対して、柔軟にコントロールできる新しい電力源として実用化が始まっている。 The polymer electrolyte fuel cell is a battery that extracts electrical energy using hydrogen and oxygen as fuel, and has the features of high power density, low temperature operation, and almost no harmful substances in the exhaust gas. Practical use has begun as a new power source that can be flexibly controlled with respect to the stationary type and in-vehicle type.
固体高分子型燃料電池のアノード極、すなわち水素反応極の燃料源には、高純度の水素ガスだけでなく、炭化水素ガス、アルコール等の水素を含む有機物質を燃料改質器に通して得られた水素富化ガスが使用されている。しかしながら、改質して得られる水素富化ガス中には、未改質の原料ガス、副生成物としての一酸化炭素が含まれており、低水素濃度の水素富化ガス中では、それら、水素以外のガスによってアノード電極が被毒され、燃料電池の性能の低下につながる。 The fuel source of the anode of the polymer electrolyte fuel cell, that is, the hydrogen reaction electrode, is obtained by passing not only high-purity hydrogen gas but also organic substances containing hydrogen such as hydrocarbon gas and alcohol through a fuel reformer. Hydrogen enriched gas is used. However, the hydrogen-enriched gas obtained by reforming contains unmodified raw material gas and carbon monoxide as a by-product, and in the hydrogen-enriched gas having a low hydrogen concentration, The anode electrode is poisoned by a gas other than hydrogen, leading to a decrease in fuel cell performance.
また、水素富化ガス中の水素濃度が低いことは、燃料源から得られる最終的なエネルギーのロスが多いことを意味する。 Also, a low hydrogen concentration in the hydrogen-enriched gas means that there is a lot of final energy loss obtained from the fuel source.
燃料の改質行程は、大きく分けて、原料の脱硫行程、燃料ガスの改質行程、改質ガス中の一酸化炭素除去行程を含んでいる。燃料ガスの改質には、燃料ガスと等量の水蒸気を高温で反応させて水素富化ガスを得る水蒸気改質による水素生成法が用いられるが、この行程での改質効率が、最終的な水素富化ガスの純度に対して、非常に大きな影響を与えることが知られている。 The fuel reforming process is roughly divided into a raw material desulfurization process, a fuel gas reforming process, and a carbon monoxide removal process in the reformed gas. For reforming of fuel gas, a hydrogen generation method using steam reforming in which an equal amount of water vapor is reacted with fuel gas at a high temperature to obtain a hydrogen-enriched gas is used. It is known to have a very large influence on the purity of a new hydrogen-enriched gas.
水素生成触媒としては、Ｎｉなどの卑金属が用いられるが、８００℃といった高温で酸化されてしまい、触媒活性が低下することが知られている。 As the hydrogen generation catalyst, a base metal such as Ni is used, but it is known that it is oxidized at a high temperature of 800 ° C. and the catalytic activity is lowered.
一方、Ｐｔなどの貴金属は温度に対する安定性が高いものの、触媒活性が低いという問題があり、ＮｉやＰｔを遷移金属と合金化することによって温度安定性と触媒活性を向上させた合金系の触媒も存在する（例えば、特許文献１参照。）。 On the other hand, although noble metals such as Pt have high temperature stability, there is a problem that the catalytic activity is low, and an alloy-based catalyst in which temperature stability and catalytic activity are improved by alloying Ni or Pt with a transition metal. (For example, refer to Patent Document 1).
ただし、貴金属が高価であること、水蒸気改質反応時の温度は、その燃料や、動作条件によって変動するため、温度に対してより安定な触媒が要求されていることからジルコニアなどの酸化物に金属を担持した触媒が開発されている（例えば、特許文献２参照。）。
しかしながら、このような酸化物触媒も、水素生成反応時の燃料や、動作条件による大きな温度変動に対して十分なものではなく、特に、低温度域で高活性、かつ高温度域で耐熱性、耐酸化性に優れるようなものではない。 However, such an oxide catalyst is also not sufficient for a large temperature fluctuation due to the fuel during the hydrogen generation reaction and the operating conditions, in particular, high activity in the low temperature range and heat resistance in the high temperature range, It is not something that excels in oxidation resistance.
本発明は、低温度域での高い触媒活性と、高温度域での高い耐熱性、耐酸化性とを併せ持つ触媒を水素生成反応触媒として提供することを目的とする。 An object of the present invention is to provide a catalyst having both high catalytic activity in a low temperature range and high heat resistance and oxidation resistance in a high temperature range as a hydrogen generation reaction catalyst.
この課題を解決するために、本発明では高温においては耐酸化性に優れ、低温においても金属の触媒活性を向上させる効果のある複合酸化物を見出すと共に、該複合酸化物と、Ｐｔなどの貴金属から構成される触媒を水素生成反応触媒として用いることが、水素生成反応時における改質効率を格段に向上し、ひいては燃料電池の特性向上に対しても極めて有効であることを見出し、本発明を完成するに至ったものである。 In order to solve this problem, the present invention finds a complex oxide that has excellent oxidation resistance at high temperatures and has an effect of improving the catalytic activity of the metal even at low temperatures, and the complex oxide and a noble metal such as Pt. It has been found that the use of a catalyst composed of the above as a hydrogen production reaction catalyst significantly improves the reforming efficiency during the hydrogen production reaction, and thus is extremely effective in improving the characteristics of the fuel cell. It has come to be completed.
本発明の水素生成反応触媒において用いられる複合酸化物は、下記化学式（１） The composite oxide used in the hydrogen generation reaction catalyst of the present invention has the following chemical formula (1)
（式中のＡはアルカリ土類金属元素、アルカリ金属元素、ランタノイド、イットリウムおよびスカンジウムよりなる群から選ばれた少なくとも１種の元素を示し、Ｂは遷移金属元素より選ばれた少なくとも１種の元素を示す。δは酸素欠損量または酸素過剰量を表す。）で表され、ペロブスカイト構造を有する複合酸化物であり、Ｐｔ、Ｒｕ、Ｐｄ、Ａｇ等の貴金属と組み合わせて用いられること望ましい。さらに好ましくは、化学式（１）のＡが、下記化学式（２） (In the formula, A represents at least one element selected from the group consisting of alkaline earth metal elements, alkali metal elements, lanthanoids, yttrium and scandium, and B represents at least one element selected from transition metal elements. Is a composite oxide having a perovskite structure, and is preferably used in combination with a noble metal such as Pt, Ru, Pd, or Ag. More preferably, A in the chemical formula (1) is the following chemical formula (2):
である、下記化学式（１’） The following chemical formula (1 ')
で表され、ペロブスカイト構造を有する複合酸化物であり、その電子状態が電荷移動型に分類されるものであることが望ましい。ここで、上記式中のＡ’は、ランタノイド、イットリウムおよびスカンジウムよりなる群から選ばれた少なくと１種の元素を示し、Ａ”はアルカリ金属元素およびアルカリ土類金属元素よりなる群から選ばれた少なくとも１種の元素であり、ｘは０≦ｘ≦０．３、好ましくは０≦ｘ≦０．２であり、Ｂは遷移金属元素より選ばれた少なくとも１種の元素である。ｘが上記に規定する範囲を外れると酸素が過剰に欠損する、また、ペロブスカイト構造を保てなくなる。 And a composite oxide having a perovskite structure, and its electronic state is preferably classified as a charge transfer type. Here, A ′ in the above formula represents at least one element selected from the group consisting of lanthanoids, yttrium and scandium, and A ″ is selected from the group consisting of alkali metal elements and alkaline earth metal elements. At least one element, x is 0 ≦ x ≦ 0.3, preferably 0 ≦ x ≦ 0.2, and B is at least one element selected from transition metal elements. Outside the range specified above, oxygen is lost excessively and the perovskite structure cannot be maintained.
上記式（１）ないし（１’）における酸素欠損量または酸素過剰量を表すδは、特に規定はないが、ペロブスカイト構造を維持するために、δ＜０．５であることが望ましい。δの範囲としては、好ましくは−０．１５＜δ＜０．５である。また特に好ましくは−０．０５＜δ＜０．２である。すなわち、上記式（１）ないし（１’）の複合酸化物では、酸素が欠損している必要はなく（すなわち、０＜δである必要はなく、例えば、後述する実施例３のように０＞δであってもよいし、δ＝０であってもよい。）、δはペロブスカイト構造を維持するためだけにその範囲を限定されるものである。逆に言えばペロブスカイト構造が維持される限りδはその条件を満たしているとも言える。よって、δが上記に規定するδ＜０．５の範囲を多少外れても複合酸化物がペロブスカイト構造を有するものであれば、本発明の範囲に含まれるものである。この酸素欠損量δは、化学滴定によって調べることができる（後述する実施例でも当該測定法により調べた）。また、複合酸化物のペロブスカイト構造の確認は粉末Ｘ線回折測定によって行うことができる（後述する実施例でも当該測定法により調べた）。 Δ representing the amount of oxygen deficiency or oxygen excess in the above formulas (1) to (1 ′) is not particularly defined, but it is desirable that δ <0.5 in order to maintain the perovskite structure. The range of δ is preferably −0.15 <δ <0.5. Particularly preferably, -0.05 <δ <0.2. That is, in the composite oxides of the above formulas (1) to (1 ′), oxygen does not need to be deficient (that is, 0 <δ does not have to be satisfied, for example, as in Example 3 described later, 0 > Δ or δ = 0.), Δ is limited in scope only to maintain the perovskite structure. Conversely, as long as the perovskite structure is maintained, δ satisfies the condition. Therefore, even if δ slightly deviates from the range of δ <0.5 defined above, any composite oxide having a perovskite structure is included in the scope of the present invention. This amount of oxygen deficiency δ can be examined by chemical titration (in the examples described later, this measurement method was also used). In addition, confirmation of the perovskite structure of the composite oxide can be performed by powder X-ray diffraction measurement (in the examples described later, this measurement method was also used).
ここで、本発明で言う遷移金属元素とは、元素番号２２番のＴｉ〜２９番のＣｕ、４０番のＺｒ〜４７番のＡｇ、７２番のＨｆ〜７９番のＡｕ、８９番のＡｃ〜１０３番のＬｒまでの元素をいう。すなわち、通常、遷移金属元素に含まれる希土類元素（元素番号２１番のスカンジウム（Ｓｃ）、元素番号３９番のイットリウム（Ｙ）および元素番号５７番のランタン（Ｌａ）から７１番のルテチウム（Ｌｕ）までのランタノイド）は含まないものとする。 Here, the transition metal element referred to in the present invention is the element number 22 Ti to 29th Cu, the number 40 Zr to the 47th Ag, the 72nd Hf to the 79th Au, the 89th Ac to Elements up to 103rd Lr. That is, usually rare earth elements contained in transition metal elements (element No. 21 scandium (Sc), element No. 39 yttrium (Y), and element No. 57 lanthanum (La) to No. 71 lutetium (Lu)) Lanthanoids) are not included.
アルカリ金属元素は、周期表１族の金属元素をいい、Ｌｉ、Ｎａ、Ｋ、Ｒｂ、Ｃｓ、Ｆｒをいう。アルカリ土類金属元素は、周期表２族の金属元素のうち、Ｂｅ、Ｍｇを除く、Ｃａ、Ｓｒ、Ｂａ、Ｒａをいう。 An alkali metal element refers to a metal element belonging to Group 1 of the periodic table, and refers to Li, Na, K, Rb, Cs, and Fr. The alkaline earth metal element refers to Ca, Sr, Ba, and Ra, excluding Be and Mg, among the metal elements of Group 2 of the periodic table.
複合酸化物において、その電子状態は遷移金属のｄ電子が伝導を担うモットー・ハバード型と、酸素の２ｐ軌道より生成されたホールが伝導を担う電荷移動型に分類される。従来の複合酸化物触媒はモットー・ハバード型であったが、触媒活性が十分でなく、近年、電荷移動型の複合酸化物において触媒活性が高いことが見出された（Ｆ．Ｍｕｎａｋａｔａ ｅｔ．ａｌ． Ｐｈｙｓｉｃａｌ Ｒｅｖｉｅｗ Ｂ， ５６巻 ３号 ９７９〜９８２ページ （１９９７））。前記化学式（１’）で表される複合酸化物は、その電子状態がこの電荷移動型で、電子系のキャリアが複合酸化物中の酸素の２ｐ軌道より生成されたホールであることが必要である。かかる複合酸化物の電子状態は、陽イオン元素（Ａサイト、Ｂサイト）の置換によって電荷移動型となるように制御することができ、モットー・ハバードと電荷移動型による電子状態の違いはＸＰＳ（Ｘ線光電子分光）測定を用いて観測することができる（後述する実施例でも当該測定法により調べた）。 In the composite oxide, the electronic state is classified into the Mott-Hubbard type in which the d-electron of the transition metal is responsible for conduction and the charge transfer type in which the hole generated from the 2p orbit of oxygen is responsible for conduction. Conventional composite oxide catalysts have been of the Mott-Hubbard type, but their catalytic activity is not sufficient, and in recent years, it has been found that charge transfer type composite oxides have high catalytic activity (F. Munakata et.al. Physical Review B, Vol. 56, No. 3, pages 979-982 (1997)). The complex oxide represented by the chemical formula (1 ′) needs to have an electron state of this charge transfer type, and an electron carrier is a hole generated from a 2p orbit of oxygen in the complex oxide. is there. The electronic state of the composite oxide can be controlled to be a charge transfer type by substitution of a cation element (A site, B site), and the difference between the electronic states of Mott Hubbard and the charge transfer type is XPS ( It can be observed by using X-ray photoelectron spectroscopy (measured by the measurement method in Examples described later).
上記複合酸化物の陽イオン元素のＡサイトとしては、化学式（２）；Ａ’１−ｘＡ”ｘで表されるものが好ましく、このうち、Ａ’としては、イオン半径の観点から、Ｌａ、Ｎｄが特に望ましい。Ａ”としては、イオン半径の観点から、Ｓｒ、Ｂａ、Ｃｓ、Ｋが特に望ましい。すなわち、Ａサイトに用いられる元素のうち、アルカリ金属元素としては、Ｃｓ、Ｋが、アルカリ土類金属元素としては、Ｂａ、Ｓｒが、ランタノイドとしては、Ｌａ、Ｎｄが特に好ましい元素と言える。複合酸化物の陽イオン元素のＢサイトとしては、イオン半径の観点から、Ｃｏ、Ｎｉ、Ｆｅが好ましい元素と言える。さらに（Ｆｅ，Ｍｎ）、（Ｃｏ，Ｍｎ）などＭｎ等と組み合わせてもよい。 The A site of the cation element of the composite oxide is preferably represented by the chemical formula (2); A ′ 1-x A ″ x. Among these, A ′ is La from the viewpoint of the ionic radius. Nd is particularly desirable. As A ″, Sr, Ba, Cs, and K are particularly desirable from the viewpoint of the ionic radius. That is, among the elements used in the A site, Cs and K are particularly preferable as the alkali metal elements, Ba and Sr are particularly preferable as the alkaline earth metal elements, and La and Nd are particularly preferable as the lanthanoid elements. As the B site of the cation element of the composite oxide, it can be said that Co, Ni, and Fe are preferable elements from the viewpoint of the ionic radius. Further, (Fe, Mn), (Co, Mn), etc. may be combined with Mn.
この水素生成触媒用複合酸化物は、一般的な固相反応法を用いても作製できるが、より活性の高い粉末を得るためには、クエン酸塩法、シュウ酸塩法のような液相法を用いることが望ましく、得られた二次粒子の平均粒径は、５μｍ以下であることが好ましく、１μｍ以下であることがより望ましい。得られた二次粒子の平均粒径が５μｍを超える場合には比表面積が減少し、活性が低下する。なお、水素生成触媒用複合酸化物の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定することができる。すなわち、得られる耐一酸化炭素被毒触媒用複合酸化物の微粉末は、凝集等して二次粒子を形成する、もしくは凝集等してアグロマレート（集塊物）を形成し、それが二次的に集まって二次粒子を形成したものである。 This composite oxide for hydrogen generation catalyst can be produced using a general solid phase reaction method, but in order to obtain a more active powder, a liquid phase such as the citrate method or the oxalate method is used. The average particle diameter of the obtained secondary particles is preferably 5 μm or less, and more preferably 1 μm or less. When the average particle diameter of the obtained secondary particles exceeds 5 μm, the specific surface area decreases and the activity decreases. The average particle size of the secondary particles of the composite oxide for hydrogen generation catalyst can be measured by a light scattering type particle size distribution meter. That is, the obtained fine powder of the composite oxide for a carbon monoxide-resistant poisoning catalyst is agglomerated to form secondary particles, or agglomerated to form agglomerates (aggregates), which are secondary Are gathered together to form secondary particles.
この複合酸化物と組み合わせて用いられる金属は、少なくとも１種の貴金属である必要があり、複合酸化物に対して、重量比として、少なくとも０．１ｗｔ％、好ましくは０．５〜１０ｗｔ％の範囲で用いられることが望ましい。ここで、この複合酸化物と組み合わせて用いられる貴金属の使用量が、０．１ｗｔ％未満の場合には十分な活性が得られないおそれがある。なお、貴金属の使用量の上限値については、特に制限されるものではないが、凝集による比表面積低下を防止する観点から、１５ｗｔ％とするのが望ましい。この複合酸化物と組み合わせて用いられる貴金属（合金を含む）の使用の方法、形状、形態は問わないが、それら貴金属の微粒子が、複合酸化物の二次粒子中に含浸、または二次粒子の表面に分布していることが望ましい。かかる貴金属を微粒子の形態で用いる場合には、該貴金属微粒子の平均粒径は１００ｎｍ以下、好ましくは１０ｎｍ以下である。該貴金属微粒子の平均粒径が２００ｎｍを超える場合には、貴金属微粒子の表面積（触媒としての作用面積）が十分でなく、また複合酸化物の二次粒子中の間隙に含浸させるのが困難となったり、複合酸化物の二次粒子表面への均一な分布が困難となる。なお、貴金属微粒子の平均粒径の下限値は特に制限されるべきものではない。この貴金属の微粒子の平均粒径は、例えば、透過型電子顕微鏡などを用いて測定することができる。貴金属微粒子の粒径は、絶対最大長を用いるものとする。 The metal used in combination with the composite oxide must be at least one kind of noble metal, and the weight ratio with respect to the composite oxide is at least 0.1 wt%, preferably in the range of 0.5 to 10 wt%. It is desirable to be used in. Here, if the amount of the noble metal used in combination with the composite oxide is less than 0.1 wt%, sufficient activity may not be obtained. The upper limit of the amount of noble metal used is not particularly limited, but is preferably 15 wt% from the viewpoint of preventing a decrease in specific surface area due to aggregation. The method, shape and form of the noble metals (including alloys) used in combination with this composite oxide are not limited, but the noble metal fine particles are impregnated into the secondary particles of the composite oxide, or the secondary particles It is desirable to be distributed on the surface. When such noble metal is used in the form of fine particles, the average particle size of the noble metal fine particles is 100 nm or less, preferably 10 nm or less. When the average particle diameter of the noble metal fine particles exceeds 200 nm, the surface area (acting area as a catalyst) of the noble metal fine particles is not sufficient, and it becomes difficult to impregnate the gaps in the secondary particles of the composite oxide. In other words, it is difficult to uniformly distribute the composite oxide on the secondary particle surface. In addition, the lower limit of the average particle diameter of the noble metal fine particles is not particularly limited. The average particle diameter of the noble metal fine particles can be measured using, for example, a transmission electron microscope. The absolute maximum length is used as the particle diameter of the noble metal fine particles.
本発明において、上記複合酸化物と組み合わせて用いられる貴金属（合金を含む）は、Ａｕ、Ａｇ、白金族元素（Ｒｕ、Ｒｈ、Ｐｄ、Ｏｓ、Ｉｒ、Ｐｔ）の金属及びこれらの合金の中から使用目的に応じて、最適なものを適宜選択して使用することができるものであるが、耐久性、安定性という観点から、Ｐｔ、Ｒｈ、Ｐｄ、Ｒｕ、Ａｇからなる群より選ばれてなる少なくとも１種のものが望ましく、より好ましくはＰｔである。 In the present invention, noble metals (including alloys) used in combination with the above complex oxide are Au, Ag, platinum group metals (Ru, Rh, Pd, Os, Ir, Pt) and alloys thereof. Depending on the purpose of use, the optimum one can be selected and used as appropriate, but from the viewpoint of durability and stability, it is selected from the group consisting of Pt, Rh, Pd, Ru, and Ag. At least one is desirable, more preferably Pt.
この水素生成触媒を用いることで、燃料ガスに対する水素生成反応がスムーズに進行し、燃料の改質効率が向上し、かつこの触媒が電荷移動型の電子構造を持つ複合酸化物であるために、耐久性に優れ、高温での動作時、長時間の運転において、安定な触媒作用を提供することになる。 By using this hydrogen generation catalyst, the hydrogen generation reaction to the fuel gas proceeds smoothly, the reforming efficiency of the fuel is improved, and this catalyst is a complex oxide having a charge transfer electronic structure. It is excellent in durability, and provides stable catalytic action during long-time operation when operating at high temperatures.
本発明における水素生成触媒材料において、上記化学式（１）で表され、ペロブスカイト構造を有する複合酸化物を、炭化水素、酸素および水蒸気を含むガスから、少なくとも水蒸気改質反応を利用して水素燃料を生成する水素生成触媒として用いることにより、好ましくは上記化学式（１）と少なくとも１種の貴金属から構成されるものを該水素生成触媒として用いることにより、より好ましくは上記化学式（１’）で表されるペロブスカイト構造を有する複合酸化物であり、その電子状態が電荷移動型に分類されるものと、少なくとも１種の貴金属を、上記複合酸化物に対して、重量比として、少なくとも０．１ｗｔ％の範囲で用いて構成されたことを特徴とする該水素生成触媒を用いることにより、金属または単純な酸化物にＰｔなどを担持させた場合（比較例１〜３参照のこと）に比べて、高温でも高い安定性を保ちながら、低温でも炭化水素ガス、アルコールなどの水蒸気改質反応率を高め、高い効率で水素を回収でき、水素生成触媒として上記触媒材料を用いることにより、水蒸気改質反応を含む水素燃料改質器の性能を向上させることができる。 In the hydrogen generation catalyst material according to the present invention, the composite oxide represented by the above chemical formula (1) and having a perovskite structure is converted from a gas containing hydrocarbon, oxygen, and steam to hydrogen fuel using at least a steam reforming reaction. When used as a hydrogen generation catalyst to be produced, preferably, the compound represented by the above chemical formula (1) and at least one noble metal is used as the hydrogen generation catalyst, and more preferably represented by the above chemical formula (1 ′). A composite oxide having a perovskite structure whose electronic state is classified as a charge transfer type and at least one precious metal at a weight ratio of at least 0.1 wt% with respect to the composite oxide. By using the hydrogen generation catalyst characterized by being used in a range, Pt or the like can be added to a metal or a simple oxide. Compared to the case of carrying (see Comparative Examples 1 to 3), while maintaining high stability even at high temperatures, the steam reforming reaction rate of hydrocarbon gas, alcohol, etc. is increased even at low temperatures, and hydrogen is recovered with high efficiency. In addition, by using the catalyst material as a hydrogen generation catalyst, the performance of the hydrogen fuel reformer including the steam reforming reaction can be improved.
本発明の水素生成触媒は、上記化学式（１）で表され、ペロブスカイト構造を有する複合酸化物を用いてなることを特徴とするものであって、炭化水素、酸素および水蒸気を含むガスから、少なくとも水蒸気改質反応を利用して水素燃料を生成し得るものである。好ましくは上記化学式（１’）で表され、ペロブスカイト構造を有し、その電子状態が電荷移動型であることを特徴とする複合酸化物であり、より好ましくはこれらの複合酸化物とＰｔ等の貴金属から構成されてなるものであり、特にこれらの複合酸化物と、少なくとも１種の貴金属を、該複合酸化物に対して、重量比として、少なくとも０．１ｗｔ％用いて構成されてなるものであって、炭化水素、酸素および水蒸気を含むガスから、少なくとも水蒸気改質反応を利用して水素燃料を生成し得るものである。これにより、炭化水素ガス、アルコール等、水素を含む燃料ガスを、固体高分子型燃料電池のアノード極、すなわち水素反応極の燃料源に適した水素富化ガスに改質することができるものである。 The hydrogen generation catalyst of the present invention is characterized by using a composite oxide represented by the above chemical formula (1) and having a perovskite structure, comprising at least a gas containing hydrocarbon, oxygen and water vapor. Hydrogen fuel can be generated using a steam reforming reaction. Preferably, it is a complex oxide represented by the above chemical formula (1 ′) and having a perovskite structure, and its electronic state is a charge transfer type, more preferably these complex oxides such as Pt and the like In particular, these composite oxides and at least one noble metal are used at a weight ratio of at least 0.1 wt% with respect to the composite oxide. Thus, hydrogen fuel can be generated from a gas containing hydrocarbon, oxygen, and steam by utilizing at least a steam reforming reaction. As a result, a fuel gas containing hydrogen, such as hydrocarbon gas or alcohol, can be reformed into a hydrogen-enriched gas suitable for the anode electrode of the solid polymer fuel cell, that is, the fuel source of the hydrogen reaction electrode. is there.
化学式（１）；ＡＢＯ３−δ（式中のＡはアルカリ土類金属元素、アルカリ金属元素、ランタノイド、イットリウムおよびスカンジウムよりなる群から選ばれた少なくとも１種の元素を示し、Ｂは遷移金属元素より選ばれた少なくとも１種の元素を示し、δは酸素欠損量または酸素過剰量を表す。）、好ましくは化学式（１’）；Ａ’１−ｘＡ”ｘＢＯ３−δ（式中のＡ’は、ランタノイド、イットリウムおよびスカンジウムよりなる群から選ばれた少なくとも１種の元素を示し、Ａ”はアルカリ金属元素およびアルカリ土類金属元素よりなる群から選ばれた少なくとも１種の元素であり、ｘは０≦ｘ≦０．３、好ましくは０≦ｘ≦０．２であり、Ｂは遷移金属元素より選ばれた少なくとも１種の元素である必要がある。δに特に規定はないが、ペロブスカイト構造を維持するために、δ＜０．５であることが望ましい。）で表され、ペロブスカイト構造を有する複合酸化物であり、その電子状態が電荷移動型に分類されるものは、固相反応法、クエン酸法やペチニ法といったほとんどすべての酸化物の合成法を用いて得ることが出来、その粉末は、二次粒子径の平均値において、大きくとも５μｍ以下の微粉末であり、粉末としてのみならず、粒状やペレット状の形状に成型して用いること、スラリーやペーストにして、水素ガスを得るための水素生成触媒（燃料改質触媒）として燃料改質器の担体（担持体ないし基材）等に塗布するなどして用いることも出来る。 Chemical formula (1); ABO 3-δ (wherein A represents at least one element selected from the group consisting of alkaline earth metal elements, alkali metal elements, lanthanoids, yttrium, and scandium, and B represents a transition metal element) Represents at least one element selected from δ, and δ represents an oxygen deficiency amount or an oxygen excess amount.), Preferably chemical formula (1 ′); A ′ 1−x A ″ x BO 3−δ (wherein A ′ represents at least one element selected from the group consisting of lanthanoids, yttrium and scandium, and A ″ is at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements. , X is 0 ≦ x ≦ 0.3, preferably 0 ≦ x ≦ 0.2, and B must be at least one element selected from transition metal elements. In order to maintain the perovskite structure, it is desirable that δ <0.5), and a composite oxide having a perovskite structure whose electronic state is classified as a charge transfer type is a solid oxide. It can be obtained by using almost all oxide synthesis methods such as the phase reaction method, citric acid method and petini method, and the powder is a fine powder having an average secondary particle size of 5 μm or less at the maximum, Fuel reformer carrier (support) used as a hydrogen generation catalyst (fuel reforming catalyst) for obtaining hydrogen gas, not only as a powder, but also in the form of particles or pellets and used as slurry or paste It can also be applied to a substrate) or the like.
上記（１）ないし（１’）におけるδは、ペロブスカイト構造を維持するために、δ＜０．５であることが望ましい。δの範囲としては、好ましくは−０．１５＜δ＜０．５である。また特に好ましくは−０．０５＜δ＜０．２である。 Δ in the above (1) to (1 ′) is preferably δ <0.5 in order to maintain the perovskite structure. The range of δ is preferably −0.15 <δ <0.5. Particularly preferably, -0.05 <δ <0.2.
この水素生成触媒用の複合酸化物は、一般的な固相反応法を用いても作製できるが、より活性の高い粉末を得るためには、クエン酸塩法、シュウ酸塩法のような液相法を用いることが望ましく、得られた二次粒子径は５μｍ以下である必要があり、１μｍ以下であることが望ましい。これら液相法の製造方法は、既に公知な製法として確立されており、クエン酸塩法は、後述する実施例に記載した特開平２−７４５０５号公報に記載された方法と同様にして製造することができるものであり、シュウ酸塩法に関しても、同様に従来公知の製法を用いて製造することができる。 This composite oxide for a hydrogen generation catalyst can be prepared by using a general solid phase reaction method, but in order to obtain a more active powder, a liquid such as a citrate method or an oxalate method is used. It is desirable to use a phase method, and the obtained secondary particle size needs to be 5 μm or less, and desirably 1 μm or less. Production methods for these liquid phase methods have already been established as known production methods, and the citrate method is produced in the same manner as the method described in JP-A-2-74505 described in Examples described later. As for the oxalate method, it can be similarly produced using a conventionally known production method.
上記水素生成触媒用の複合酸化物において、その電子構造は電荷移動型（Ｆ．Ｍｕｎａｋａｔａ ｅｔ．ａｌ． Ｐｈｙｓｉｃａｌ Ｒｅｖｉｅｗ Ｂ， ５６巻 ３号 ９７９〜９８２ページ （１９９７）参照のこと。）である必要があり、電子系のキャリアが複合酸化物中の酸素の２ｐ軌道より生成されたホールであることが必要である。 In the composite oxide for a hydrogen generation catalyst, the electronic structure thereof must be a charge transfer type (see F. Munakata et.al. Physical Review B, Vol. 56, No. 3, pages 979 to 982 (1997)). It is necessary that the electron carrier is a hole generated from the 2p orbit of oxygen in the composite oxide.
この水素生成触媒用の複合酸化物と組み合わせて用いられる金属は、少なくとも１種の貴金属（合金を含む）からなる必要があり、該複合酸化物に対して、重量比として、少なくとも０．１ｗｔ％、好ましくは０．５〜１０ｗｔ％の範囲で用いるのが望ましい。上記複合酸化物と組み合わせて用いられる貴金属の使用の方法、形状、形態は問わないが、それら貴金属の微粒子が、複合酸化物の二次粒子中に含浸、または二次粒子の表面に分布していることが望ましい。該貴金属としては、特に制限されるものではないが、Ｐｔ、Ｒｈ、Ｐｄ、ＲｕおよびＡｇよりなる群から選ばれた少なくとも１種の金属（合金を含む）が耐久性、安定性という観点から望ましく、特に望ましくはＰｔである。 The metal used in combination with the composite oxide for the hydrogen generation catalyst needs to be composed of at least one kind of noble metal (including an alloy), and the weight ratio to the composite oxide is at least 0.1 wt%. It is desirable to use in the range of 0.5 to 10 wt%. The method, shape and form of the noble metal used in combination with the composite oxide are not limited, but the fine particles of the noble metal are impregnated in the composite oxide secondary particles or distributed on the surface of the secondary particles. It is desirable. The noble metal is not particularly limited, but at least one metal (including an alloy) selected from the group consisting of Pt, Rh, Pd, Ru and Ag is desirable from the viewpoint of durability and stability. Particularly preferred is Pt.
このように、電荷移動型の電子構造を持ち、高温でも安定な複合酸化物、更に好ましくは該複合酸化物と、Ｐｔなどの貴金属を組み合わせることによって、Ｐｔなどの貴金属の電子状態に変化を与え、低温でも酸素の活性を高めるため、高い水素生成触媒活性を維持できると考えられる。この作用に基づいて、本発明を実施するに至ったものである。 As described above, a composite oxide having a charge transfer electronic structure and stable even at high temperatures, more preferably, by combining the composite oxide with a noble metal such as Pt, changes the electronic state of the noble metal such as Pt. In order to increase the activity of oxygen even at a low temperature, it is considered that a high hydrogen production catalytic activity can be maintained. Based on this action, the present invention has been implemented.
次に、本発明の水素燃料改質器では、上述した本発明の水素生成触媒を用い、少なくとも水蒸気改質反応を用いて燃料改質を行うことを特徴とするものである。また、本発明の燃料電池用水素燃料改質器では、上述した本発明の水素生成触媒を用い、改質用の燃料として炭化水素ガスを用い、オートサーマル反応を用いて燃料改質を行うことを特徴とするものである。 Next, the hydrogen fuel reformer of the present invention is characterized in that fuel reforming is performed using at least a steam reforming reaction using the hydrogen generation catalyst of the present invention described above. In the fuel cell hydrogen fuel reformer of the present invention, the above-described hydrogen generation catalyst of the present invention is used, hydrocarbon gas is used as the reforming fuel, and fuel reforming is performed using an autothermal reaction. It is characterized by.
上記水素燃料改質器としては、燃料電池用水素燃料改質器のほか、少なくとも水蒸気改質反応を用いて燃料改質を行うことのできる従来公知の各種水素燃料改質器に適用しえるものである。 As the hydrogen fuel reformer, in addition to a hydrogen fuel reformer for a fuel cell, it can be applied to various conventionally known hydrogen fuel reformers that can perform fuel reforming using at least a steam reforming reaction. It is.
また、燃料電池用水素燃料改質器としては、定置型、車載型などの各種固体高分子型燃料電池用水素燃料改質器のほか、改質用の燃料として炭化水素ガスを用い、オートサーマル反応を用いて燃料改質を行うことのできる従来公知の各種燃料電池用水素燃料改質器に適用しえるものである。 In addition to hydrogen fuel reformers for solid polymer fuel cells such as stationary and in-vehicle types, hydrogen fuel reformers for fuel cells use hydrocarbon gas as reforming fuel, and autothermal The present invention can be applied to various well-known hydrogen fuel reformers for fuel cells that can perform fuel reforming using a reaction.
以下に本発明を実施例、比較例によって詳細に説明するが、本発明はこれら実施例に限定されるものではなく、金属を複合酸化物中に含浸させることは、必ずしも必要ではない。 Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and it is not always necessary to impregnate a complex oxide with a metal.
（実施例１）Ｌａ０．９Ｓｒ０．１Ｆｅ０．５Ｍｎ０．５Ｏ３−δ＋０．５％Ｐｔ
ランタン、ストロンチウム、マンガンの炭酸塩、もしくは水酸化物、鉄のクエン酸塩を出発原料とし、組成比（原子比）がＬａ：Ｓｒ：Ｆｅ：Ｍｎ＝０．９：０．１：０．５：０．５となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２００℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ０．０３であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。また、該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｐｔの重量が担体である該複合酸化物微粉末に対して０．５ｗｔ％となるように調整し、中和したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した複合酸化物微粉末を得た。このＰｔ担持複合酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持複合酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 1) La 0.9 Sr 0.1 Fe 0.5 Mn 0. 5O 3-δ + 0.5% Pt
Starting from lanthanum, strontium, manganese carbonate or hydroxide, iron citrate, the composition ratio (atomic ratio) is La: Sr: Fe: Mn = 0.9: 0.1: 0.5 : 0.5, and in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, calcining at 600 ° C. for 10 hours, A powder obtained by firing at 1200 ° C. for 10 hours in the air was pulverized by a ball mill to obtain a composite oxide fine powder having an average particle size adjusted to 5 μm or less. The oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was 0.03 as determined by chemical titration. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement, and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Pt was 0.5 wt% with respect to the composite oxide fine powder as a carrier, and impregnated with a neutralized dinitrodiamine platinum nitric acid solution at 450 ° C. Firing was performed for 6 hours, and further pulverized to obtain a fine powder of composite oxide carrying Pt. The average particle size of the Pt fine particles of this Pt-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Pt-supported composite oxide fine powder is placed in a quartz reaction vessel as a hydrogen generation catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is flowed into the reaction vessel, and the components of the discharged gas are analyzed by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（実施例２）Ｌａ０．８Ｂａ０．２Ｆｅ０．２Ｍｎ０．８Ｏ３−δ＋０．５％Ｐｔ
ランタン、バリウム、マンガンの炭酸塩、もしくは水酸化物、鉄のクエン酸塩を出発原料とし、組成比（原子比）がＬａ：Ｂａ：Ｆｅ：Ｍｎ＝０．８：０．２：０．２：０．８となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２５０℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ０．０８であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。また、該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｐｔの重量が担体である該複合酸化物微粉末に対して０．５ｗｔ％となるように調整し、中和したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した複合酸化物微粉末を得た。このＰｔ担持複合酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持複合酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 2) La 0.8 Ba 0.2 Fe 0.2 Mn 0.8 O 3-δ + 0.5% Pt
Starting from lanthanum, barium, manganese carbonate or hydroxide, iron citrate, the composition ratio (atomic ratio) is La: Ba: Fe: Mn = 0.8: 0.2: 0.2 : In addition to 0.8, in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, calcining at 600 ° C. for 10 hours, The powder obtained by firing at 1250 ° C. for 10 hours in the air was pulverized with a ball mill to obtain a composite oxide fine powder having an average particle size adjusted to 5 μm or less. The amount of oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was 0.08 when examined by chemical titration. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement, and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Pt was 0.5 wt% with respect to the composite oxide fine powder as a carrier, and impregnated with a neutralized dinitrodiamine platinum nitric acid solution at 450 ° C. Firing was performed for 6 hours, and further pulverized to obtain a fine powder of composite oxide carrying Pt. The average particle size of the Pt fine particles of this Pt-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Pt-supported composite oxide fine powder is placed in a quartz reaction vessel as a hydrogen generation catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is flowed into the reaction vessel, and the components of the discharged gas are analyzed by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（実施例３）Ｌａ０．９Ｎａ０．１Ｆｅ０．４Ｍｎ０．６Ｏ３−δ＋０．５％Ｐｔ
ランタン、ナトリウム、マンガンの炭酸塩、もしくは水酸化物、鉄のクエン酸塩を出発原料とし、組成比（原子比）がＬａ：Ｎａ：Ｆｅ：Ｍｎ＝０．９：０．１：０．４：０．６となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２００℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ−０．０５（つまり、複合酸化物微粉末の組成は、Ｌａ０．９Ｎａ０．１Ｆｅ０．４Ｍｎ０．６Ｏ３．０５であり、酸素が過剰な状態であった。）であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｐｔの重量が担体である該複合酸化物微粉末に対して０．５ｗｔ％となるように調整し、中和したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した複合酸化物微粉末を得た。このＰｔ担持複合酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持複合酸化物微粉末を石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 3) La 0.9 Na 0.1 Fe 0.4 Mn 0.6 O 3-δ + 0.5% Pt
Starting from lanthanum, sodium, manganese carbonate or hydroxide, iron citrate, the composition ratio (atomic ratio) is La: Na: Fe: Mn = 0.9: 0.1: 0.4 : 0.6, and in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, calcining at 600 ° C. for 10 hours, A powder obtained by firing at 1200 ° C. for 10 hours in the air was pulverized by a ball mill to obtain a composite oxide fine powder having an average particle size adjusted to 5 μm or less. The amount of oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was -0.05 (that is, the composition of the composite oxide fine powder was La 0.9 Na 0.1 Fe 0. .4 Mn 0.6 O 3.05 and oxygen was in an excess state. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Pt was 0.5 wt% with respect to the composite oxide fine powder as a carrier, and impregnated with a neutralized dinitrodiamine platinum nitric acid solution at 450 ° C. Firing was performed for 6 hours, and further pulverized to obtain a fine powder of composite oxide carrying Pt. The average particle size of the Pt fine particles of this Pt-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Pt-supported complex oxide fine powder is placed in a quartz reaction vessel, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is allowed to flow through the reaction vessel, and the discharged gas is subjected to component analysis by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（実施例４）Ｌａ０．７Ｙ０．２Ｓｒ０．１Ｆｅ０．６Ｍｎ０．４Ｏ３−δ＋０．５％Ｐｔ
ランタン、イットリウム、ストロンチウム、マンガンの炭酸塩、もしくは水酸化物、鉄のクエン酸塩を出発原料とし、組成比（原子比）がＬａ：Ｙ：Ｓｒ：Ｆｅ：Ｍｎ＝０．７：０．２：０．１：０．６：０．４となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２５０℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ０．０５であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。また、該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｐｔの重量が担体である複合酸化物微粉末に対して０．５ｗｔ％となるように調整し、中和したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した複合酸化物微粉末を得た。このＰｔ担持複合酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持複合酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 4) La 0.7 Y 0.2 Sr 0.1 Fe 0.6 Mn 0.4 O 3-δ + 0.5% Pt
Starting from lanthanum, yttrium, strontium, manganese carbonate or hydroxide, iron citrate, the composition ratio (atomic ratio) is La: Y: Sr: Fe: Mn = 0.7: 0.2 : 0.1: 0.6: 0.4 In addition, in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, 600 A powder obtained by calcining at 10 ° C. for 10 hours and firing at 1250 ° C. for 10 hours in the air was pulverized by a ball mill to obtain a fine composite oxide powder having an average particle size adjusted to 5 μm or less. The oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was 0.05 by chemical titration. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement, and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Pt was 0.5 wt% with respect to the composite oxide fine powder as a carrier, and impregnated with a neutralized dinitrodiamine platinum nitric acid solution. After firing for a period of time, the mixture was further pulverized to obtain a composite oxide fine powder carrying Pt. The average particle size of the Pt fine particles of this Pt-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Pt-supported composite oxide fine powder is placed in a quartz reaction vessel as a hydrogen generation catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is flowed into the reaction vessel, and the components of the discharged gas are analyzed by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（実施例５）Ｌａ０．９Ｓｒ０．１Ｃｏ０．５Ｍｎ０．５Ｏ３−δ＋０．５％Ｐｔ
ランタン、ストロンチウム、コバルト、マンガンの炭酸塩、もしくは水酸化物を出発原料とし、組成比（原子比）がＬａ：Ｓｒ：Ｃｏ：Ｍｎ＝０．９：０．１：０．５：０．５となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２５０℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ０．０２であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。また、該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｐｔの重量が担体である複合酸化物微粉末に対して０．５ｗｔ％となるように調整し、中和したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した複合酸化物微粉末を得た。このＰｔ担持複合酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持複合酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 5) La 0.9 Sr 0.1 Co 0.5 Mn 0.5 O 3-δ + 0.5% Pt
Starting from lanthanum, strontium, cobalt, manganese carbonate or hydroxide, the composition ratio (atomic ratio) is La: Sr: Co: Mn = 0.9: 0.1: 0.5: 0.5 In addition, in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, calcining at 600 ° C. for 10 hours and 1250 ° C. at 10 ° C. The powder obtained by carrying out the firing for a period of time in the atmosphere was pulverized by a ball mill to obtain a composite oxide fine powder having an average particle size adjusted to 5 μm or less. The amount of oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was 0.02 as determined by chemical titration. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement, and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Pt was 0.5 wt% with respect to the composite oxide fine powder as a carrier, and impregnated with a neutralized dinitrodiamine platinum nitric acid solution. After firing for a period of time, the mixture was further pulverized to obtain a composite oxide fine powder carrying Pt. The average particle size of the Pt fine particles of this Pt-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Pt-supported composite oxide fine powder is placed in a quartz reaction vessel as a hydrogen generation catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is flowed into the reaction vessel, and the components of the discharged gas are analyzed by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（実施例６）Ｌａ０．８Ｂａ０．２Ｆｅ０．２Ｍｎ０．８Ｏ３−δ＋０．５％Ｐｔ
ランタン、バリウム、マンガンの炭酸塩、もしくは水酸化物、鉄のクエン酸塩を出発原料とし、組成比（原子比）がＬａ：Ｂａ：Ｆｅ：Ｍｎ＝０．８：０．２：０．２：０．８となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２５０℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ０．０６であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。また、該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｐｔの重量が担体である該複合酸化物微粉末に対して０．５ｗｔ％となるように調整し、中和したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した複合酸化物微粉末を得た。このＰｔ担持複合酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持複合酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 6) La 0.8 Ba 0.2 Fe 0.2 Mn 0.8 O 3-δ + 0.5% Pt
Starting from lanthanum, barium, manganese carbonate or hydroxide, iron citrate, the composition ratio (atomic ratio) is La: Ba: Fe: Mn = 0.8: 0.2: 0.2 : In addition to 0.8, in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, calcining at 600 ° C. for 10 hours, The powder obtained by firing at 1250 ° C. for 10 hours in the air was pulverized with a ball mill to obtain a composite oxide fine powder having an average particle size adjusted to 5 μm or less. The amount of oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was 0.06 as determined by chemical titration. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement, and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Pt was 0.5 wt% with respect to the composite oxide fine powder as a carrier, and impregnated with a neutralized dinitrodiamine platinum nitric acid solution at 450 ° C. Firing was performed for 6 hours, and further pulverized to obtain a fine powder of composite oxide carrying Pt. The average particle size of the Pt fine particles of this Pt-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Pt-supported composite oxide fine powder is placed in a quartz reaction vessel as a hydrogen generation catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is flowed into the reaction vessel, and the components of the discharged gas are analyzed by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（実施例７）Ｌａ０．９Ｓｒ０．１Ｆｅ０．５Ｍｎ０．５Ｏ３−δ＋１％Ｒｈ
ランタン、ストロンチウム、マンガンの炭酸塩、もしくは水酸化物、鉄のクエン酸塩を出発原料とし、組成比（原子比）がＬａ：Ｓｒ：Ｆｅ：Ｍｎ＝０．９：０．１：０．５：０．５となるように加え、特開平２−７４５０５号公報に記載された方法と同様にして、クエン酸と反応させ複合クエン酸塩粉末を製造後、６００℃で１０時間の仮焼、１２５０℃で１０時間の焼成を大気中で行って得られた粉末をボールミルで粉砕し、平均粒径５μｍ以下に粒度調整された複合酸化物微粉末を得た。得られた複合酸化物微粉末の酸素欠損量または酸素過剰量δは化学滴定によって調べたところ０．０６であった。この複合酸化物微粉末のペロブスカイト構造の確認は粉末Ｘ線回折測定によった。また、該複合酸化物の電子状態は、ＸＰＳ（Ｘ線光電子分光）測定を用いて観測し、電荷移動型であることを確認した。更に、この複合酸化物微粉末の二次粒子の平均粒径は、光散乱方式の粒度分布計によって測定した結果、１μｍであった。この複合酸化物微粉末に、Ｒｈの重量が担体である該複合酸化物微粉末に対して１．０ｗｔ％となるように調整し、中和したロジウム硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｒｈを担持した複合酸化物微粉末を得た。このＲｈ担持複合酸化物微粉末のＲｈ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＲｈ担持複合酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Example 7) La 0.9 Sr 0.1 Fe 0.5 Mn 0.5 O 3-δ + 1% Rh
Starting from lanthanum, strontium, manganese carbonate or hydroxide, iron citrate, the composition ratio (atomic ratio) is La: Sr: Fe: Mn = 0.9: 0.1: 0.5 : 0.5, and in the same manner as described in JP-A-2-74505, after reacting with citric acid to produce a composite citrate powder, calcining at 600 ° C. for 10 hours, The powder obtained by firing at 1250 ° C. for 10 hours in the air was pulverized with a ball mill to obtain a composite oxide fine powder having an average particle size adjusted to 5 μm or less. The amount of oxygen deficiency or oxygen excess δ of the obtained composite oxide fine powder was 0.06 as determined by chemical titration. Confirmation of the perovskite structure of the composite oxide fine powder was performed by powder X-ray diffraction measurement. The electronic state of the composite oxide was observed using XPS (X-ray photoelectron spectroscopy) measurement, and confirmed to be a charge transfer type. Furthermore, the average particle diameter of the secondary particles of the composite oxide fine powder was 1 μm as a result of measurement by a light scattering type particle size distribution meter. The composite oxide fine powder was adjusted so that the weight of Rh was 1.0 wt% with respect to the composite oxide fine powder as a support, impregnated with a neutralized rhodium nitric acid solution, and at 450 ° C. for 6 hours. Was fired and further pulverized to obtain a composite oxide fine powder carrying Rh. The average particle diameter of the Rh fine particles of this Rh-supported composite oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This Rh-supported composite oxide fine powder is placed in a quartz reaction vessel as a hydrogen production catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is passed through the reaction vessel, and the exhausted gas is subjected to component analysis by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（比較例１）Ａｌ２Ｏ３＋０．５％Ｐｔ
市販品のアルミナに、Ｐｔの重量が担体である該アルミナに対して０．５ｗｔ％となるように調整したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した酸化物微粉末を得た。このＰｔ担持酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
Comparative Example 1 Al 2 O 3 + 0.5% Pt
Commercially available alumina is impregnated with a dinitrodiamine platinum nitric acid solution adjusted so that the weight of Pt is 0.5 wt% with respect to the alumina as a carrier, fired at 450 ° C. for 6 hours, and further pulverized. Thus, a fine oxide powder carrying Pt was obtained. The average particle diameter of the Pt fine particles of this Pt-supported oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This fine Pt-supported oxide powder is placed in a quartz reaction vessel as a hydrogen production catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is passed through the reaction vessel, and the exhausted gas is subjected to component analysis by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（比較例２）ＺｒＯ２＋０．５％Ｐｔ
市販品のジルコニアに、Ｐｔの重量が担体である該ジルコニアに対して０．５ｗｔ％となるように調整したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した酸化物微粉末を得た。このＰｔ担持酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Comparative Example 2) ZrO 2 + 0.5% Pt
Commercially available zirconia is impregnated with a dinitrodiamine platinum nitric acid solution adjusted so that the weight of Pt is 0.5 wt% with respect to the zirconia as a carrier, fired at 450 ° C. for 6 hours, and further pulverized. Thus, a fine oxide powder carrying Pt was obtained. The average particle diameter of the Pt fine particles of this Pt-supported oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This fine Pt-supported oxide powder is placed in a quartz reaction vessel as a hydrogen production catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is passed through the reaction vessel, and the exhausted gas is subjected to component analysis by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（比較例３）ＣｅＯ２＋０．５％Ｐｔ
市販品のセリアに、Ｐｔの重量が担体である該セリアに対して０．５ｗｔ％となるように調整したジニトロジアミン白金硝酸溶液を含浸させ、４５０℃で６時間の焼成を行い、さらに粉砕し、Ｐｔを担持した酸化物微粉末を得た。このＰｔ担持酸化物微粉末のＰｔ微粒子の平均粒径は、透過型電子顕微鏡を用いて測定した結果、５ｎｍであった。このＰｔ担持酸化物微粉末を水素生成触媒として石英反応菅内に配置し、流量調整されたメタンと酸素と水蒸気を含む混合ガスを反応菅に流し、排出されたガスをガスクロマトグラフィーによって成分分析を行い、該水素生成触媒の性能評価を行った。
(Comparative Example 3) CeO 2 + 0.5% Pt
Commercially available ceria is impregnated with a dinitrodiamine platinum nitric acid solution adjusted so that the weight of Pt is 0.5 wt% with respect to the ceria which is a carrier, fired at 450 ° C. for 6 hours, and further pulverized. Thus, a fine oxide powder carrying Pt was obtained. The average particle diameter of the Pt fine particles of this Pt-supported oxide fine powder was 5 nm as a result of measurement using a transmission electron microscope. This fine Pt-supported oxide powder is placed in a quartz reaction vessel as a hydrogen production catalyst, a mixed gas containing methane, oxygen and water vapor whose flow rate is adjusted is passed through the reaction vessel, and the exhausted gas is subjected to component analysis by gas chromatography. The performance of the hydrogen generation catalyst was evaluated.
（試験例）
実施例１〜７および比較例１〜３で得られた水素生成触媒性能を、下記の条件下で評価を行うことにより判断した。
(Test example)
The hydrogen generation catalyst performance obtained in Examples 1 to 7 and Comparative Examples 1 to 3 was judged by evaluating under the following conditions.
（水素生成触媒性能）
水素生成触媒性能は、触媒反応前の入力ガス中のメタン濃度、水蒸気濃度、触媒反応後の出力ガス中のメタン濃度、水蒸気濃度、水素濃度をガスクロマトグラフィーによって分析することで評価した。
(Hydrogen production catalyst performance)
The hydrogen generation catalyst performance was evaluated by analyzing the methane concentration, water vapor concentration, and methane concentration, water vapor concentration, and hydrogen concentration in the output gas after the catalytic reaction by gas chromatography before the catalytic reaction.
（ガス分析反応条件）
メタンと水蒸気を１％：３％の割合（質量比）で含み、表１のように組成を調整したガスを６００℃に予熱しながら、流量２０Ｌ／ｈｒにて、０．５ｃｃの触媒を設置した石英反応菅に流通させて、水素を含むガスを得た。反応前と反応後のガスに含まれるメタン濃度、水蒸気濃度、水素濃度から、触媒の水素生成率を求めた。
(Gas analysis reaction conditions)
A 0.5 cc catalyst was installed at a flow rate of 20 L / hr while preheating the gas containing methane and water vapor at a ratio of 1%: 3% (mass ratio) and adjusted in composition as shown in Table 1 to 600 ° C. The gas containing hydrogen was supplied to the quartz reaction vessel. The hydrogen production rate of the catalyst was determined from the methane concentration, water vapor concentration, and hydrogen concentration contained in the gas before and after the reaction.
以上のようにして得られたガス分析による水素生成率を実施例１〜７および比較例１〜３について表２に示す。 The hydrogen production rates by gas analysis obtained as described above are shown in Table 2 for Examples 1 to 7 and Comparative Examples 1 to 3.
これらの結果から明らかなように、本発明における水素生成触媒材料において、化学式ＡＢＯ３−δ（式中のＡはアルカリ土類金属元素、アルカリ金属元素、ランタノイド、イットリウムおよびスカンジウムよりなる群から選ばれた少なくとも１種の元素を示し、Ｂは遷移金属元素より選ばれた少なくとも１種の元素を示し、δは酸素欠損量または酸素過剰量を表す。）、とりわけ式中のＡがＡ’１−ｘＡ”ｘである、化学式Ａ’１−ｘＡ”ｘＢＯ３−δ（式中のＡ’は、ランタノイド、イットリウムおよびスカンジウムよりなる群から選ばれた少なくと１種の元素を示し、Ａ”はアルカリ金属元素およびアルカリ土類金属元素よりなる群から選ばれた少なくとも１種の元素を示し、ｘが０≦ｘ≦０．３であり、Ｂは遷移金属元素より選ばれた少なくとも１種の元素を示し、δは酸素欠損量または酸素過剰量を表す。）で表されるペロブスカイト構造を有する複合酸化物であり、その電子状態が電荷移動型に分類されるものと、少なくとも１種の貴金属を、該複合酸化物に対して、重量比として、少なくとも０．１ｗｔ％用いて構成されたことを特徴とする水素生成触媒を用いることにより、炭化水素ガス、アルコールなどの水蒸気改質反応率を高め、高い効率で水素を回収でき、水素生成触媒として、上記触媒材料が有用であることが示された。 As is clear from these results, in the hydrogen generation catalyst material of the present invention, the chemical formula ABO 3-δ (where A is selected from the group consisting of alkaline earth metal elements, alkali metal elements, lanthanoids, yttrium, and scandium). And B represents at least one element selected from transition metal elements, and δ represents an oxygen deficiency or oxygen excess), in particular, A in the formula is A ′ 1− x A ″ x , a chemical formula A ′ 1-x A ″ x BO 3-δ (where A ′ represents at least one element selected from the group consisting of lanthanoids, yttrium and scandium; “Represents at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements, x is 0 ≦ x ≦ 0.3, and B is selected from transition metal elements A compound oxide having a perovskite structure represented by: δ represents an oxygen deficiency amount or an oxygen excess amount, and its electronic state is classified as a charge transfer type, By using a hydrogen generation catalyst characterized by comprising at least 0.1 wt% of at least one precious metal as a weight ratio with respect to the composite oxide, water vapor such as hydrocarbon gas or alcohol is used. It was shown that the above catalyst material is useful as a hydrogen generation catalyst because the reforming reaction rate is increased and hydrogen can be recovered with high efficiency.
Claims (7)
少なくとも１種の貴金属を、複合酸化物に対して、重量比として、少なくとも０．１ｗｔ％用いて構成されることを特徴とする請求項１〜４のいずれか１項に記載の水素生成触媒。 The composite oxide;
5. The hydrogen generation catalyst according to claim 1, wherein at least one noble metal is used in a weight ratio of at least 0.1 wt% with respect to the composite oxide.
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