JP2005322430A - Ternary alloy, catalyst for fuel cell, and fuel cell - Google Patents
Ternary alloy, catalyst for fuel cell, and fuel cell Download PDFInfo
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- JP2005322430A JP2005322430A JP2004137209A JP2004137209A JP2005322430A JP 2005322430 A JP2005322430 A JP 2005322430A JP 2004137209 A JP2004137209 A JP 2004137209A JP 2004137209 A JP2004137209 A JP 2004137209A JP 2005322430 A JP2005322430 A JP 2005322430A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 94
- 239000000446 fuel Substances 0.000 title claims abstract description 47
- 229910002058 ternary alloy Inorganic materials 0.000 title claims abstract description 17
- 239000010419 fine particle Substances 0.000 claims abstract description 57
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910002849 PtRu Inorganic materials 0.000 claims abstract description 39
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 32
- 239000000758 substrate Substances 0.000 claims abstract description 26
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 81
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 44
- 239000002245 particle Substances 0.000 claims description 39
- 229910045601 alloy Inorganic materials 0.000 claims description 34
- 239000000956 alloy Substances 0.000 claims description 34
- 125000004434 sulfur atom Chemical group 0.000 claims description 24
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 22
- 150000003839 salts Chemical class 0.000 claims description 19
- 150000001875 compounds Chemical class 0.000 claims description 14
- 238000004519 manufacturing process Methods 0.000 claims description 14
- 238000010992 reflux Methods 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 10
- 239000003960 organic solvent Substances 0.000 claims description 9
- 239000012298 atmosphere Substances 0.000 claims description 6
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 5
- 150000001298 alcohols Chemical class 0.000 claims description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 3
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 3
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical compound OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 2
- 239000002253 acid Substances 0.000 abstract description 12
- 231100000572 poisoning Toxicity 0.000 abstract description 10
- 230000000607 poisoning effect Effects 0.000 abstract description 10
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 54
- 235000019441 ethanol Nutrition 0.000 description 41
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 39
- 239000000243 solution Substances 0.000 description 33
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 18
- 229910002091 carbon monoxide Inorganic materials 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 14
- 238000010248 power generation Methods 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 230000003647 oxidation Effects 0.000 description 11
- 238000007254 oxidation reaction Methods 0.000 description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 9
- 238000000635 electron micrograph Methods 0.000 description 9
- 229910052697 platinum Inorganic materials 0.000 description 9
- RTZYCRSRNSTRGC-LNTINUHCSA-K (z)-4-oxopent-2-en-2-olate;ruthenium(3+) Chemical compound [Ru+3].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O RTZYCRSRNSTRGC-LNTINUHCSA-K 0.000 description 8
- 230000003197 catalytic effect Effects 0.000 description 8
- 230000007423 decrease Effects 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- 229910052739 hydrogen Inorganic materials 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- VEJOYRPGKZZTJW-FDGPNNRMSA-N (z)-4-hydroxypent-3-en-2-one;platinum Chemical compound [Pt].C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O VEJOYRPGKZZTJW-FDGPNNRMSA-N 0.000 description 7
- 238000009835 boiling Methods 0.000 description 7
- 229910052707 ruthenium Inorganic materials 0.000 description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 6
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 6
- 239000012299 nitrogen atmosphere Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 229920000557 Nafion® Polymers 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000012528 membrane Substances 0.000 description 5
- 239000005518 polymer electrolyte Substances 0.000 description 5
- 229910052723 transition metal Inorganic materials 0.000 description 5
- 150000003624 transition metals Chemical class 0.000 description 5
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 4
- AMQJEAYHLZJPGS-UHFFFAOYSA-N N-Pentanol Chemical compound CCCCCO AMQJEAYHLZJPGS-UHFFFAOYSA-N 0.000 description 4
- 230000010718 Oxidation Activity Effects 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 4
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 description 4
- 239000000084 colloidal system Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- PHTQWCKDNZKARW-UHFFFAOYSA-N isoamylol Chemical compound CC(C)CCO PHTQWCKDNZKARW-UHFFFAOYSA-N 0.000 description 4
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 4
- 230000001681 protective effect Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- -1 alkali metal salt Chemical class 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- BTOOAFQCTJZDRC-UHFFFAOYSA-N 1,2-hexadecanediol Chemical compound CCCCCCCCCCCCCCC(O)CO BTOOAFQCTJZDRC-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 229910002056 binary alloy Inorganic materials 0.000 description 2
- JUPWRUDTZGBNEX-UHFFFAOYSA-N cobalt;pentane-2,4-dione Chemical compound [Co].CC(=O)CC(C)=O.CC(=O)CC(C)=O.CC(=O)CC(C)=O JUPWRUDTZGBNEX-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 235000011187 glycerol Nutrition 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229940035429 isobutyl alcohol Drugs 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- BMGNSKKZFQMGDH-FDGPNNRMSA-L nickel(2+);(z)-4-oxopent-2-en-2-olate Chemical compound [Ni+2].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O BMGNSKKZFQMGDH-FDGPNNRMSA-L 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 2
- 235000019345 sodium thiosulphate Nutrition 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 239000011865 Pt-based catalyst Substances 0.000 description 1
- 229910002848 Pt–Ru Inorganic materials 0.000 description 1
- ITFCTBFBEKRKDC-UHFFFAOYSA-N [O].OC Chemical compound [O].OC ITFCTBFBEKRKDC-UHFFFAOYSA-N 0.000 description 1
- CTUFHBVSYAEMLM-UHFFFAOYSA-N acetic acid;platinum Chemical compound [Pt].CC(O)=O.CC(O)=O CTUFHBVSYAEMLM-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 229940045985 antineoplastic platinum compound Drugs 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 238000011074 autoclave method Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010537 deprotonation reaction Methods 0.000 description 1
- AXAIHGXEQFPLFL-UHFFFAOYSA-L dichlorobismuth Chemical compound Cl[Bi]Cl AXAIHGXEQFPLFL-UHFFFAOYSA-L 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- WMNIETDRLRTYFX-UHFFFAOYSA-N ethane-1,2-diamine;platinum Chemical compound [Pt].NCCN WMNIETDRLRTYFX-UHFFFAOYSA-N 0.000 description 1
- FNMHUFUGHKNGPT-UHFFFAOYSA-N ethane-1,2-diamine;ruthenium Chemical compound [Ru].NCCN FNMHUFUGHKNGPT-UHFFFAOYSA-N 0.000 description 1
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- ILHIHKRJJMKBEE-UHFFFAOYSA-N hydroperoxyethane Chemical compound CCOO ILHIHKRJJMKBEE-UHFFFAOYSA-N 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- AQBLLJNPHDIAPN-LNTINUHCSA-K iron(3+);(z)-4-oxopent-2-en-2-olate Chemical compound [Fe+3].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O AQBLLJNPHDIAPN-LNTINUHCSA-K 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 150000002941 palladium compounds Chemical class 0.000 description 1
- 150000003058 platinum compounds Chemical class 0.000 description 1
- NWAHZABTSDUXMJ-UHFFFAOYSA-N platinum(2+);dinitrate Chemical compound [Pt+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O NWAHZABTSDUXMJ-UHFFFAOYSA-N 0.000 description 1
- XAKYZBMFCZISAU-UHFFFAOYSA-N platinum;triphenylphosphane Chemical compound [Pt].C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 XAKYZBMFCZISAU-UHFFFAOYSA-N 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 150000003138 primary alcohols Chemical class 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- OJLCQGGSMYKWEK-UHFFFAOYSA-K ruthenium(3+);triacetate Chemical compound [Ru+3].CC([O-])=O.CC([O-])=O.CC([O-])=O OJLCQGGSMYKWEK-UHFFFAOYSA-K 0.000 description 1
- BIXNGBXQRRXPLM-UHFFFAOYSA-K ruthenium(3+);trichloride;hydrate Chemical compound O.Cl[Ru](Cl)Cl BIXNGBXQRRXPLM-UHFFFAOYSA-K 0.000 description 1
- GTCKPGDAPXUISX-UHFFFAOYSA-N ruthenium(3+);trinitrate Chemical compound [Ru+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O GTCKPGDAPXUISX-UHFFFAOYSA-N 0.000 description 1
- VIHDTGHDWPVSMM-UHFFFAOYSA-N ruthenium;triphenylphosphane Chemical compound [Ru].C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 VIHDTGHDWPVSMM-UHFFFAOYSA-N 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 150000003333 secondary alcohols Chemical class 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 229910001428 transition metal ion Inorganic materials 0.000 description 1
- 238000010792 warming 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
Landscapes
- Inert Electrodes (AREA)
- Fuel Cell (AREA)
Abstract
Description
本発明は燃料電池用触媒に関する。更に詳細には、本発明は直接メタノール型燃料電池或いは高分子電解質型燃料電池に好適な微細粒径均一性に優れた白金系触媒と、それを用いた燃料電池及びその製造方法に関する。 The present invention relates to a fuel cell catalyst. More specifically, the present invention relates to a platinum-based catalyst excellent in fine particle size uniformity suitable for a direct methanol fuel cell or a polymer electrolyte fuel cell, a fuel cell using the same, and a method for producing the same.
従来、電気エネルギーの大部分は、火力発電、水力発電又は原子力発電などにより供給されてきた。しかし、火力発電は石油や石炭などの化石燃料を燃焼させるため大規模な環境汚染をもたらすばかりか、石油などの資源枯渇が問題視されるようになってきた。また、水力発電は大規模なダム建設を必要とし、それによる自然破壊が懸念されるばかりか、建設適地も限られている。原子力発電は事故の際の放射能汚染が致命的であるばかりか、寿命を迎えた原子炉の廃炉問題などもあり、世界的には建設が抑制される方向に動いている。 Conventionally, most of electric energy has been supplied by thermal power generation, hydroelectric power generation or nuclear power generation. However, thermal power generation not only causes large-scale environmental pollution because it burns fossil fuels such as oil and coal, but depletion of resources such as oil has become a problem. In addition, hydropower generation requires large-scale dam construction, and not only is there concern about the destruction of nature, but there are also limited areas for construction. Nuclear power generation is not only fatal in the radioactive contamination at the time of the accident, but also has a problem of decommissioning nuclear reactors that have reached the end of their life, and is moving in a direction that suppresses construction worldwide.
大規模な施設を必要とせず、環境汚染も起こさない発電方法として風力発電や太陽光発電が世界各国で利用されるようになり、我が国でも一部の地域で実際に風力発電や太陽光発電が実用化されている。しかし、風力発電は風が吹かなければ発電できず、また太陽光発電は日光照射がなければ発電できないなど、自然現象に左右され、安定的な電力供給ができないという欠点がある。また、風力発電では、風の強さにより、発電した電力の周波数が変動し、電気機器の故障原因となっていた。 Wind power generation and solar power generation have been used around the world as power generation methods that do not require large-scale facilities and do not cause environmental pollution. In Japan, wind power generation and solar power generation are actually used in some areas. It has been put into practical use. However, wind power generation has a drawback in that it cannot generate power without wind, and solar power generation cannot generate power without sunlight, and is affected by natural phenomena and cannot provide stable power supply. Further, in wind power generation, the frequency of the generated power fluctuates due to the strength of the wind, causing a failure of electrical equipment.
そこで、最近は、水素エネルギーから電気エネルギーを取り出すことができる発電装置例えば、水素燃料電池などの開発研究が活発になってきた。水素は水を分解することにより得られ、地球上に無尽蔵に存在するばかりか、物質量当たりに含まれる化学エネルギー量が大きく、しかも、エネルギー源として利用するときに有害物質や地球温暖化ガスを発生しないという利点を有する。 Therefore, recently, research and development on a power generation device that can extract electric energy from hydrogen energy, such as a hydrogen fuel cell, has become active. Hydrogen is obtained by decomposing water and not only exists infinitely on the earth, but also contains a large amount of chemical energy per amount of substance. Moreover, when it is used as an energy source, harmful substances and global warming gases are used. It has the advantage that it does not occur.
水素ガスの代わりに、メタノールを使用する燃料電池の研究も活発に行われている。液体燃料であるメタノールを直接使用するメタノール燃料電池は、燃料の取り扱い易さに加え、安価な燃料ということで家庭用や産業用の比較的小出力規模の電源として期待されている。メタノールー酸素燃料電池の理論出力電圧は、水素燃料のものとほぼ同じ１．２Ｖ（２５℃）であり、原理的には同様の特性が期待できる。 Research on fuel cells using methanol instead of hydrogen gas is also actively conducted. A methanol fuel cell that directly uses methanol, which is a liquid fuel, is expected to be a relatively small output power source for household and industrial use because it is an inexpensive fuel in addition to easy handling of the fuel. The theoretical output voltage of the methanol-oxygen fuel cell is 1.2 V (25 ° C.) which is almost the same as that of hydrogen fuel, and in principle the same characteristics can be expected.
高分子固体電解質型燃料電池や直接メタノール型燃料電池ではアノードで水素やメタノールを酸化させると同時に、カソードでは酸素を還元して電気エネルギーを取り出している。これらの酸化還元反応は常温では進み難いため、燃料電池には触媒が使用されている。初期の燃料電池では白金（Ｐｔ）を炭素基材上に析出担持させ触媒として使用してきた。Ｐｔは水素酸化やメタノール酸化に対して充分な触媒活性を有しており、これまで炭素基材上へのＰｔ触媒の析出雰囲気、つまり、析出時の外部因子を制御することにより、Ｐｔ触媒粒子を出来るだけ小さくし、Ｐｔ触媒の反応表面積を高めて使用することが試みられてきた。例えば、特許文献１では、アルコールでＰｔイオンを還元してＰｔを炭素基材上に担持させる際、反応溶液中に保護コロイドとしてポリビニルアルコールを添加し、Ｐｔ触媒粒子表面に保護コロイドを弱く吸着させ、Ｐｔ触媒の微粒子化を図っている。この方法では、Ｐｔ触媒表面に保護コロイドが吸着している。このため、Ｐｔ微粒子生成後に、水素気流中で４００℃で熱処理を行っているが、この処理方法では保護コロイドを完全にＰｔ触媒表面から取り去ることは出来ず、Ｐｔ触媒の性能を完全に発揮させることができないという問題点があった。 In a solid polymer electrolyte fuel cell and a direct methanol fuel cell, hydrogen and methanol are oxidized at the anode, and at the same time oxygen is reduced at the cathode to extract electric energy. Since these oxidation-reduction reactions are difficult to proceed at room temperature, a catalyst is used in the fuel cell. In early fuel cells, platinum (Pt) has been deposited on a carbon substrate and used as a catalyst. Pt has sufficient catalytic activity for hydrogen oxidation and methanol oxidation, and so far, by controlling the precipitation atmosphere of the Pt catalyst on the carbon substrate, that is, by controlling the external factors at the time of precipitation, Pt catalyst particles Attempts have been made to make the Pt catalyst as small as possible and increase the reaction surface area of the Pt catalyst. For example, in Patent Document 1, when Pt ions are reduced with alcohol and Pt is supported on a carbon substrate, polyvinyl alcohol is added as a protective colloid to the reaction solution, and the protective colloid is weakly adsorbed on the surface of the Pt catalyst particles. , Pt catalyst is made fine. In this method, the protective colloid is adsorbed on the surface of the Pt catalyst. For this reason, although heat treatment is performed at 400 ° C. in a hydrogen stream after the Pt fine particles are produced, the protective colloid cannot be completely removed from the surface of the Pt catalyst, and the performance of the Pt catalyst is fully exhibited. There was a problem that it was not possible.
また、Ｐｔ触媒には、メタノール酸化過程で発生する一酸化炭素（ＣＯ）、或いは水素ガス中に含まれるＣＯがＰｔ触媒上に化学吸着し、最終的には触媒活性が失活する問題があった。この現象はＣＯによる触媒被毒と呼ばれている。ＣＯによるＰｔ触媒の被毒を抑えるため、Ｐｔへの添加元素の探索が行われた。その結果、ＰｔにＲｕを添加することにより、ＣＯによる触媒被毒が大きく軽減されることが発見された（例えば、特許文献２参照）。 In addition, the Pt catalyst has a problem that carbon monoxide (CO) generated in the methanol oxidation process or CO contained in hydrogen gas is chemically adsorbed on the Pt catalyst, and eventually the catalytic activity is deactivated. It was. This phenomenon is called catalyst poisoning by CO. In order to suppress the poisoning of the Pt catalyst by CO, an element added to Pt was searched. As a result, it has been discovered that catalyst poisoning by CO is greatly reduced by adding Ru to Pt (see, for example, Patent Document 2).
このＲｕはそれ自身に水素やメタノールの酸化活性は無いが、Ｐｔ上に被着したＣＯを素早くＣＯ２に酸化して逃がす働きを持った助触媒である。直接メタノール型燃料電池を例に挙げると、下記式（１）に示されるように、Ｐｔ触媒粒子上で脱プロトン反応が起こり、Ｐｔ触媒粒子上にＣＯが化学吸着する。これがＣＯにより触媒被毒である。しかし、Ｒｕを含んだＰｔＲｕ触媒では、下記式（２）で示されるように、Ｒｕが水と反応してＰｔ−Ｒｕを生成し、次いで、下記式（３）で示されるように、Ｐｔ触媒粒子表面に化学吸着したＣＯをＣＯ２に酸化して除去する。
Ｐｔ＋ＣＨ３ＯＨ → Ｐｔ-ＣＯ ＋４Ｈ＋＋４ｅ− 式（１）
Ｒｕ＋Ｈ２Ｏ → Ｒｕ-ＯＨ＋Ｈ＋＋ｅ− 式（２）
Ｐｔ-ＣＯ＋Ｒｕ-ＯＨ → Ｐｔ＋Ｒｕ＋Ｈ＋＋ｅ−＋ＣＯ２↑ 式（３）
Although this Ru itself has no oxidation activity of hydrogen or methanol, it is a cocatalyst having a function of quickly oxidizing CO deposited on Pt to CO2 and letting it escape. Taking a direct methanol fuel cell as an example, as shown in the following formula (1), a deprotonation reaction occurs on the Pt catalyst particles, and CO is chemically adsorbed on the Pt catalyst particles. This is catalyst poisoning by CO. However, in the PtRu catalyst containing Ru, as shown in the following formula (2), Ru reacts with water to produce Pt-Ru, and then, as shown in the following formula (3), the Pt catalyst CO chemisorbed on the particle surface is oxidized to CO2 and removed.
Pt + CH 3 OH → Pt-CO + 4H + + 4e - formula (1)
Ru + H 2 O → Ru—OH + H + + e − Formula (2)
Pt—CO + Ru—OH → Pt + Ru + H + + e − + CO 2 ↑ Equation (3)
ＰｔにＲｕを添加したＰｔＲｕ触媒はＰｔのＣＯ被毒を軽減させたが、ＣＯ濃度が高い雰囲気では未だ助触媒としての能力が不十分であるばかりか、Ｒｕは貴金属元素であり、高価なことから、ＰｔＲｕ触媒に第三添加元素を加えるか、又はＲｕを除いたＰｔ系触媒の開発が試行された。例えば、特許文献３には、ＰｔＲｕ合金にＭｏを添加したＰｔＲｕＭｏ三元合金が記載されている。しかし、ＰｔＲｕ合金にＭｏを添加すると、耐ＣＯ被毒性は若干高まったが、スルフォン酸によりＭｏが溶解し、固体高分子電解質膜中のプロトンとイオン交換が起こり、その結果、プロトン導電率が低下する問題があった。また、特許文献４には、Ｒｕの代わりに、Ｍｎ及びＦｅを添加したＰｔＭｎＦｅ三元合金が記載されている。しかし、特許文献３の発明と同様に、耐ＣＯ被毒性は若干高まったが、Ｍｎ及びＦｅがスルフォン酸に溶解し、固体高分子電解質膜中のプロトンとイオン交換が起こり、その結果、プロトン導電率が低下する問題があった。また、一方では、Ｐｔに種々の添加元素を入れると、触媒粒子中のＰｔの割合が減少し、触媒活性が低下するのではないかという懸念もあった。 PtRu catalyst with Ru added to Pt has reduced CO poisoning of Pt, but it is not only insufficient as a cocatalyst in an atmosphere with high CO concentration, but Ru is a noble metal element and is expensive. Therefore, an attempt was made to develop a Pt-based catalyst in which a third additive element was added to the PtRu catalyst or Ru was removed. For example, Patent Document 3 describes a PtRuMo ternary alloy in which Mo is added to a PtRu alloy. However, when Mo was added to the PtRu alloy, the CO poisoning resistance increased slightly, but Mo was dissolved by sulfonic acid, and ion exchange with protons in the solid polymer electrolyte membrane occurred, resulting in a decrease in proton conductivity. There was a problem to do. Patent Document 4 describes a PtMnFe ternary alloy in which Mn and Fe are added instead of Ru. However, like the invention of Patent Document 3, the CO poisoning resistance is slightly increased, but Mn and Fe are dissolved in sulfonic acid, and ion exchange occurs with protons in the solid polymer electrolyte membrane, resulting in proton conduction. There was a problem that the rate decreased. On the other hand, there is also a concern that when various additive elements are added to Pt, the ratio of Pt in the catalyst particles decreases, and the catalytic activity may decrease.
従って、本発明の目的は、耐ＣＯ被毒性に優れ、かつ、酸に溶解しない第三元素を含む新規なＰｔＲｕ触媒を提供することである。 Accordingly, an object of the present invention is to provide a novel PtRu catalyst containing a third element that has excellent resistance to CO poisoning and does not dissolve in an acid.
前記課題を解決するための手段として、第１に、下記の一般式、
ＰｔＲｕＳ
（前記式中、Ｓの含有率はＰｔＲｕの総モル数に対して、０．０１モル％〜５０モル％の範囲内である。）で示されることを特徴とする三元系合金を提供する。
As means for solving the above problems, first, the following general formula:
PtRuS
(Wherein the content of S is in the range of 0.01 mol% to 50 mol% with respect to the total number of moles of PtRu), a ternary alloy is provided. .
前記課題を解決するための手段として、第２に、炭素基材上に、下記の一般式、
ＰｔＲｕＳ
で示される三元系合金微粒子を担持したことを特徴とする燃料電池用触媒を提供する。
Secondly, as a means for solving the above problems, on the carbon substrate, the following general formula:
PtRuS
The catalyst for fuel cells characterized by carrying | supporting the ternary system alloy fine particle shown by these is provided.
前記課題を解決するための手段として、第３に、前記ＰｔＲｕＳ三元系合金微粒子のＳの含有率がＰｔＲｕの総モル数に対して、０．０１モル％〜５０モル％の範囲内であることを特徴とする前記第２に記載の燃料電池用触媒を提供する。 Thirdly, as a means for solving the above problem, the S content of the PtRuS ternary alloy fine particles is in the range of 0.01 mol% to 50 mol% with respect to the total number of moles of PtRu. The fuel cell catalyst according to the second aspect is provided.
前記課題を解決するための手段として、第４に、前記ＰｔＲｕＳ三元系合金微粒子の粒径が１ｎｍ〜５ｎｍの範囲内であることを特徴とする前記第２に記載の燃料電池用触媒を提供する。 As a means for solving the above-mentioned problem, fourthly, the fuel cell catalyst according to the second aspect, wherein the PtRuS ternary alloy fine particles have a particle size in the range of 1 nm to 5 nm. To do.
前記課題を解決するための手段として、第５に、燃料電池用触媒の製造方法において、
(1)一種類以上のアルコールからなる有機溶剤中に炭素基材を分散させるステップと、
(2)前記炭素基材が分散されたアルコール系有機溶剤中に、Ｐｔの塩又は錯体と、Ｒｕの塩又は錯体と、Ｓ原子含有化合物を溶解させるステップと、
(3)炭素粉末が分散されたアルコール溶液のｐＨ値を２〜５の範囲に調整するステップと、
(4)不活性雰囲気中で、アルコールによる加熱還流を行うステップとからなり、
前記炭素基材上に、下記の一般式、
ＰｔＲｕＳ
で示される三元系合金微粒子を担持した燃料電池用触媒を生成することを特徴とする燃料電池用触媒の製造方法を提供する。
As means for solving the above problems, fifthly, in a method for producing a fuel cell catalyst,
(1) dispersing a carbon base material in an organic solvent composed of one or more alcohols;
(2) dissolving a Pt salt or complex, a Ru salt or complex, and an S atom-containing compound in an alcohol-based organic solvent in which the carbon substrate is dispersed;
(3) adjusting the pH value of the alcohol solution in which the carbon powder is dispersed to a range of 2 to 5,
(4) a step of heating and refluxing with alcohol in an inert atmosphere,
On the carbon substrate, the following general formula:
PtRuS
A fuel cell catalyst carrying the ternary alloy fine particles represented by the formula (1) is produced.
前記課題を解決するための手段として、第６に、前記ステップ(2)において、前記Ｓ原子含有化合物はＰｔの塩又は錯体とＲｕの塩又は錯体の合計モル数に対して、５モル％〜５０モル％であることを特徴とする前記第５に記載の燃料電池用触媒の製造方法を提供する。 As means for solving the above problems, sixthly, in the step (2), the S atom-containing compound is 5 mol% to 5 mol% based on the total number of moles of the Pt salt or complex and the Ru salt or complex. 5. The method for producing a fuel cell catalyst as described in 5 above, wherein the content is 50 mol%.
前記課題を解決するための手段として、第７に、前記ステップ(3)において、硫酸を滴下することによりアルコール溶液のｐＨ値を２〜５に調整することを特徴とする前記第５５に記載の燃料電池用触媒の製造方法を提供する。 As a means for solving the above-mentioned problem, seventhly, in the step (3), the pH value of the alcohol solution is adjusted to 2 to 5 by dropping sulfuric acid in the step (3). A method for producing a fuel cell catalyst is provided.
前記課題を解決するための手段として、第８に、前記ステップ(2)において、前記Ｓ原子含有化合物は＋６価未満の原子価のＳ原子を含有する化合物であることを特徴とする前記第５に記載の燃料電池用触媒の製造方法を提供する。 As a means for solving the above-mentioned problems, eighthly, in the step (2), the S atom-containing compound is a compound containing an S atom having a valence less than +6. The manufacturing method of the catalyst for fuel cells as described in 1 above is provided.
前記課題を解決するための手段として、第９に、前記Ｓ原子含有化合物は、チオ硫酸塩、亜硫酸塩、亜硫酸水素塩、過硫酸塩、ピロ硫酸塩及びピロ亜硫酸塩からなる群から選択される少なくとも一種類の化合物であることを特徴とする前記第８に記載の燃料電池用触媒の製造方法を提供する。 As a means for solving the above-mentioned problems, ninthly, the S atom-containing compound is selected from the group consisting of thiosulfate, sulfite, bisulfite, persulfate, pyrosulfate and pyrosulfite. The method for producing a fuel cell catalyst according to the eighth aspect, characterized in that it is at least one kind of compound.
前記課題を解決するための手段として、第１０に、前記第２に記載の炭素担持ＰｔＲｕＳ合金微粒子触媒をメタノール極に用いたことを特徴とするメタノール燃料電池を提供する。 As means for solving the above problems, tenthly, a methanol fuel cell is provided, wherein the carbon-supported PtRuS alloy fine particle catalyst described in the second is used for a methanol electrode.
本発明によれば、アルコール還元法により炭素基材上にＰｔＲｕ触媒微粒子を析出させる際、ＰｔＲｕ触媒微粒子中にＳ原子を添加し、ＰｔＲｕＳ三元系合金とすることにより、触媒粒子の粒径が従来のＰｔＲｕ二元系合金に比べて小さくなり、その結果、反応面積が増大し、燃料電池における触媒活性を高めることができる。しかも、Ｓ原子は強酸性の高分子固体導電膜に由来する酸にも溶解しないため、三元系合金の特性が失われることもない。 According to the present invention, when the PtRu catalyst fine particles are deposited on the carbon substrate by the alcohol reduction method, S atoms are added to the PtRu catalyst fine particles to obtain a PtRuS ternary alloy, thereby reducing the particle size of the catalyst particles. Compared with the conventional PtRu binary alloy, the reaction area is increased, and as a result, the catalytic activity in the fuel cell can be increased. Moreover, since the S atom is not dissolved in the acid derived from the strongly acidic polymer solid conductive film, the characteristics of the ternary alloy are not lost.
本発明により、ＰｔＲｕ二元系合金に対してＳ原子を添加して三元系合金とすると、Ｒｕの添加効果は維持しつつ、ＰｔＲｕ触媒粒子が炭素基材上に析出する際、そのＳ添加元素自身が粒子の内部から作用し、析出するＰｔＲｕ触媒粒子を微細化し、触媒の表面積を増大させ、触媒活性が向上されることが発見された。更に、燃料電池のアノードとカソードとの間には一般的に、高分子固体導電膜としてナフィオン膜が使用されるが、ナフィオン膜のスルホン酸基の水素原子がＨ＋となってプロトン導電性を発揮するにつれてナフィオン膜と電極触媒との界面は強酸性になる。従来のＰｔＲｕ触媒に添加されていた第三金属元素（例えば、Ｍｏ、Ｍｎ、Ｆｅ，Ｃｏ等）は耐酸性が無いため溶けてＨ＋と変換してしまうが、Ｓ元素は従来の第三金属元素の合金とは異なり、耐酸性があるため酸に溶けず、燃料電池用の触媒添加元素として極めて好適であることも発見された。 According to the present invention, when S atoms are added to a PtRu binary alloy to form a ternary alloy, the addition of S is performed when PtRu catalyst particles are precipitated on the carbon substrate while maintaining the effect of adding Ru. It has been discovered that the element itself acts from the inside of the particles to refine the deposited PtRu catalyst particles, increase the surface area of the catalyst, and improve the catalytic activity. In addition, a Nafion membrane is generally used as a polymer solid conductive film between the anode and the cathode of the fuel cell. However, the hydrogen atom of the sulfonic acid group of the Nafion membrane becomes H + and proton conductivity is increased. As it is exerted, the interface between the Nafion membrane and the electrode catalyst becomes strongly acidic. The third metal element (for example, Mo, Mn, Fe, Co, etc.) added to the conventional PtRu catalyst has no acid resistance and is dissolved and converted into H + , but the S element is the conventional third metal. It has also been discovered that, unlike an elemental alloy, it has acid resistance and therefore does not dissolve in acid, making it extremely suitable as a catalyst additive element for fuel cells.
本発明による燃料電池用の触媒として使用できる新規な合金は下記の一般式により示される。
ＰｔＲｕＳ
前記式中、Ｓの含有率はＰｔＲｕの総モル数に対して、０．０１モル％〜５０モル％の範囲内であることが好ましい。Ｓの含有率が５０モル％超ではＰｔＲｕの含有率が低くなり過ぎ、電気出力に悪影響を及ぼすので好ましくない。
A novel alloy that can be used as a catalyst for a fuel cell according to the present invention is represented by the following general formula:
PtRuS
In said formula, it is preferable that the content rate of S exists in the range of 0.01 mol%-50 mol% with respect to the total mol number of PtRu. If the S content exceeds 50 mol%, the PtRu content is too low, which adversely affects the electrical output.
また、前記三元系合金におけるＰｔとＲｕの比率は特に限定されないが、２０at％≦Ｐｔ≦８０at％、２０at％≦Ｒｕ≦８０at％の範囲内であることが好ましい。Ｒｕが２０at％未満の場合、十分にＣＯ被毒特性を改善させることができないなどの不都合が生じるので好ましくない。また、Ｐｔが８０at％超の場合、Ｐｔの消費量が多く、コスト高になるなどの不都合が生じるので好ましくない。一般的に、４０at％≦Ｐｔ≦６０at％の範囲内であり、６０at％≦Ｒｕ≦４０at％の範囲内であることが一層好ましい。 The ratio of Pt and Ru in the ternary alloy is not particularly limited, but is preferably in the range of 20 at% ≦ Pt ≦ 80 at% and 20 at% ≦ Ru ≦ 80 at%. If Ru is less than 20 at%, such a disadvantage that the CO poisoning characteristics cannot be sufficiently improved is not preferable. Further, when Pt exceeds 80 at%, the amount of consumption of Pt is large and disadvantages such as high cost occur, which is not preferable. Generally, it is in the range of 40 at% ≦ Pt ≦ 60 at%, and more preferably in the range of 60 at% ≦ Ru ≦ 40 at%.
本発明のＰｔＲｕＳ触媒微粒子の製造方法は基本的に、(1)一種類以上のアルコールからなる有機溶剤中に炭素基材を分散させるステップと、(2)前記炭素基材が分散されたアルコール系有機溶剤中に、Ｐｔの塩又は錯体と、Ｒｕの塩又は錯体と、Ｓ原子含有化合物を溶解させるステップと、(3)炭素粉末が分散されたアルコール溶液のｐＨ値を２〜５の範囲に調整するステップと、(4)不活性雰囲気中で、アルコールによる加熱還流を行うステップとからなる。 The method for producing PtRuS catalyst fine particles of the present invention basically includes (1) a step of dispersing a carbon substrate in an organic solvent composed of one or more kinds of alcohol, and (2) an alcohol system in which the carbon substrate is dispersed. A step of dissolving a salt or complex of Pt, a salt or complex of Ru, and an S atom-containing compound in an organic solvent; and (3) the pH value of the alcohol solution in which the carbon powder is dispersed is in the range of 2 to 5. And (4) heating and refluxing with alcohol in an inert atmosphere.
図１は前記の製造方法により得られた本発明のＰｔＲｕＳ触媒微粒子１の模式的断面図である。炭素基材３に担持されたＰｔＲｕ粒子５の外表面にＳ原子７が配位している。Ｓ原子７は大気中の酸素により酸化され、酸化物として存在することもある。このＰｔＲｕ粒子５の外表面Ｓ原子７が配位することにより、ＰｔＲｕ粒子５の成長が止められ、ＰｔＲｕＳ触媒微粒子１全体が微細化されるものと思われる。 FIG. 1 is a schematic cross-sectional view of a PtRuS catalyst fine particle 1 of the present invention obtained by the above production method. S atoms 7 are coordinated to the outer surface of the PtRu particles 5 supported on the carbon substrate 3. The S atom 7 is oxidized by oxygen in the atmosphere and may exist as an oxide. It is considered that the outer surface S atoms 7 of the PtRu particles 5 are coordinated, so that the growth of the PtRu particles 5 is stopped and the entire PtRuS catalyst fine particles 1 are miniaturized.
白金、ルテニウム及び硫黄原子が溶解されたアルコール溶液のｐＨ値を２〜５に調整することにより、ＰｔＲｕＳ微粒子表面の組成及び粒径が最適化し、前記の反応式（６）で示したＣＯの酸化反応が効率的に進行し、メタノール酸化活性が高まるものと思われる。ｐＨ２未満では粒径が増加してメタノール酸化に有効な表面積が減少すると共に、Ｐｔの多い微粒子組成となり、触媒活性が低下する。一方、ｐＨ５超の場合、粒径の減少によりメタノール酸化に不活性な結晶面が表面に現れるため、触媒活性が低下する。特に、合金微粒子の粒径が１ｎｍよりも小さくなりすぎると、結晶の安定な面、例えば（１１１）面を触媒表面に出そうとするので、活性が低下する。 By adjusting the pH value of the alcohol solution in which platinum, ruthenium and sulfur atoms are dissolved to 2 to 5, the composition and particle size of the surface of the PtRuS fine particles are optimized, and the oxidation of CO shown in the above reaction formula (6) It is considered that the reaction proceeds efficiently and the methanol oxidation activity increases. If the pH is less than 2, the particle size increases and the effective surface area for methanol oxidation decreases, and the fine particle composition with a large amount of Pt results, resulting in a decrease in catalytic activity. On the other hand, when the pH is more than 5, the crystal surface inactive to methanol oxidation appears on the surface due to the decrease in particle size, so that the catalytic activity decreases. In particular, if the particle diameter of the alloy fine particles is too small, the activity decreases because a stable surface of the crystal, for example, the (111) surface tends to appear on the catalyst surface.
本発明の製造方法により生成されたＰｔＲｕＳ触媒微粒子の粒径は、Ｓ原子の存在と酸性ｐＨ処理との相乗効果により従来のＰｔＲｕ触媒微粒子の粒径よりも小さくなる。一般的に、本発明のＰｔＲｕＳ触媒微粒子の粒径は１ｎｍ〜５ｎｍの範囲内である。本発明のＰｔＲｕＳ触媒微粒子の別の特徴は、粒径の分布範囲が従来のＰｔＲｕ触媒微粒子の粒径分布範囲に比べて狭いことである。従来の方法で製造されたＰｔＲｕ触媒微粒子の粒径分布の中心は５ｎｍ超になり、粒子の更なる微細化は困難であった。これに対し、本発明では、ＰｔＲｕ合金にＳ原子を加え、ＰｔＲｕＳ三元合金とすることによりこの問題点を解決することに成功した。 The particle size of the PtRuS catalyst fine particles produced by the production method of the present invention is smaller than the particle size of the conventional PtRu catalyst fine particles due to the synergistic effect of the presence of S atoms and the acidic pH treatment. Generally, the particle diameter of the PtRuS catalyst fine particles of the present invention is in the range of 1 nm to 5 nm. Another feature of the PtRuS catalyst fine particles of the present invention is that the particle size distribution range is narrower than the particle size distribution range of conventional PtRu catalyst fine particles. The center of the particle size distribution of the PtRu catalyst fine particles produced by the conventional method exceeds 5 nm, and it is difficult to further refine the particles. In contrast, in the present invention, this problem was successfully solved by adding S atoms to the PtRu alloy to obtain a PtRuS ternary alloy.
本発明で使用されるＰｔの塩又は錯体は、例えば、酢酸白金、硝酸白金、白金エチレンジアミン錯体、白金トリフェニルホスフィン錯体、白金アンミン錯体、ビス（アセチルアセトナト）白金(II)及び六塩化白金酸などである。これらの白金化合物は単独で使用することもできるし又は２種類以上を併用することもできる。 Examples of the salt or complex of Pt used in the present invention include platinum acetate, platinum nitrate, platinum ethylenediamine complex, platinum triphenylphosphine complex, platinum ammine complex, bis (acetylacetonato) platinum (II) and hexachloroplatinic acid. Etc. These platinum compounds can be used alone or in combination of two or more.
本発明で使用されるＲｕの塩又は錯体は、例えば、塩化ルテニウム水和物、酢酸ルテニウム、硝酸ルテニウム、ルテニウムトリフェニルホスフィン錯体、ルテニウムアンミン錯体、ルテニウムエチレンジアミン錯体、ルテニウムアセチルアセトナート錯体（例えば、トリス（アセチルアセトナト）ルテニウム(III)等）などである。これらのパラジウム化合物は単独で使用することもできるし又は２種類以上を併用することもできる。 Examples of the Ru salt or complex used in the present invention include ruthenium chloride hydrate, ruthenium acetate, ruthenium nitrate, ruthenium triphenylphosphine complex, ruthenium ammine complex, ruthenium ethylenediamine complex, ruthenium acetylacetonate complex (for example, tris (Acetylacetonato) ruthenium (III) and the like). These palladium compounds can be used alone or in combination of two or more.
本発明で使用するＳの塩は、＋６価未満の原子価のＳ原子含有化合物であることが好ましい。＋６価の原子価を有するＳ原子は、Ｎｅと同じ電子配置であるため、オクテット則により化学的に安定となるので本発明の目的には適さない。従って、＋６価のＳ原子を有する硫酸（Ｈ２ＳＯ４）は本発明では使用できない。本発明で使用できるＳの塩は、例えば、チオ硫酸塩、亜硫酸塩、亜硫酸水素塩、過硫酸塩、ピロ硫酸塩又はピロ亜硫酸塩などである。塩としては、アルカリ金属塩などが好ましい。例えば、チオ硫酸ナトリウムなどが好適である。 The salt of S used in the present invention is preferably an S atom-containing compound having a valence of less than +6. An S atom having a valence of +6 is not suitable for the purpose of the present invention because it has the same electronic configuration as Ne and is chemically stable by the octet rule. Therefore, sulfuric acid having +6 valent S atoms (H 2 SO 4 ) cannot be used in the present invention. Examples of the salt of S that can be used in the present invention include thiosulfate, sulfite, bisulfite, persulfate, pyrosulfate, and pyrosulfite. As the salt, an alkali metal salt or the like is preferable. For example, sodium thiosulfate is suitable.
アルコール溶液のｐＨ値を２〜５に調整するために使用される酸としては沸点が２００℃以上の酸であることが好ましい。その理由は、アルコールの加熱還流が１９０℃程度の温度で行われるからである。沸点が２００℃未満の酸の場合、アルコールの加熱還流の際に消散しまう可能性があり、ｐＨ値を所定範囲内に維持することが困難になる。本発明で使用する酸としては沸点が２９０℃の硫酸が好ましい。 The acid used for adjusting the pH value of the alcohol solution to 2 to 5 is preferably an acid having a boiling point of 200 ° C. or higher. This is because the alcohol is heated and refluxed at a temperature of about 190 ° C. In the case of an acid having a boiling point of less than 200 ° C., it may be dissipated when the alcohol is heated to reflux, making it difficult to maintain the pH value within a predetermined range. The acid used in the present invention is preferably sulfuric acid having a boiling point of 290 ° C.
アルコール系溶媒に合金微粒子形成金属の供給源を溶解させ、アルコール系溶媒の沸点近傍の温度で還流すると、アルコール（Ｒ-ＯＨ）が加熱還流中に金属イオンを還元し、自らは酸化されてアルデヒド（Ｒ-ＣＨＯ）に変化する。 When the alloy fine particle-forming metal source is dissolved in an alcohol solvent and refluxed at a temperature near the boiling point of the alcohol solvent, the alcohol (R—OH) reduces the metal ions during the heating and reflux, and is oxidized and aldehyde It changes to (R-CHO).
本発明の加熱還流処理で使用されるとしては、沸点の高いアルコールが高温での還流が出来るため還元速度が高まり好ましい。使用に適したアルコールとしては、エチルアルコール、エチレングリコール、グリセリン、プロピレングリコール、イソアミルアルコール、ｎ-アミルアルコール、ｓｅｃ-ブチルアルコール、ｎ-ブチルアルコール、イソブチルアルコール、アリルアルコール、ｎ-プロピルアルコール、２-エトキシアルコール及び１，２-ヘキサデカンジオールが挙げられる。これらアルコールは１種類又は２種類以上を適宜選択して使用することができる。通常、アルコール単独では、その酸化還元電位の大きさから遷移金属の還元剤としては十分ではない。しかし、反応過程で触媒作用を有する貴金属のＰｔが存在するため、Ｐｔと遷移金属イオンを共存させ、且つアルコールの沸点で加熱還流させることによりＲｕなどの遷移金属も同時に還元析出し、遷移金属と貴金属から成る金属合金微粒子（ＰｔＲｕ）が生成すると考えられる。また、エチルアルコールの様な沸点の低いアルコールでも加圧下(オートクレープ法)で還流すれば使用する事が出来る。還流の際、微粒子の酸化を防止するため、反応系内を窒素或いはアルゴン等の不活性ガスで置換しながら還流を行うことが好ましい。 As used in the heat-refluxing treatment of the present invention, alcohol having a high boiling point can be refluxed at a high temperature, so that the reduction rate is increased. Suitable alcohols for use include ethyl alcohol, ethylene glycol, glycerin, propylene glycol, isoamyl alcohol, n-amyl alcohol, sec-butyl alcohol, n-butyl alcohol, isobutyl alcohol, allyl alcohol, n-propyl alcohol, 2- Examples include ethoxy alcohol and 1,2-hexadecanediol. These alcohols can be used by appropriately selecting one kind or two or more kinds. Normally, alcohol alone is not sufficient as a transition metal reducing agent because of its redox potential. However, since there is a noble metal Pt that has a catalytic action in the reaction process, Pt and a transition metal ion coexist, and by heating and refluxing at the boiling point of the alcohol, a transition metal such as Ru is simultaneously reduced and precipitated. It is considered that metal alloy fine particles (PtRu) made of noble metal are generated. In addition, alcohol having a low boiling point such as ethyl alcohol can be used if it is refluxed under pressure (autoclave method). In refluxing, in order to prevent oxidation of the fine particles, it is preferable to perform reflux while replacing the inside of the reaction system with an inert gas such as nitrogen or argon.
アルコール加熱還流処理における加熱温度及び還流時間は使用するアルコールの種類に応じて変化する。しかし、一般的に、加熱温度は１９０℃程度であり、還流時間は３０分間〜６時間の範囲内である。反応の終点は溶液の色が黒色に変化することにより確認できる。出発物質のＲｕ及びＰｔイオンが全て還元されたことが確認されたら加熱還流処理を終了する。 The heating temperature and reflux time in the alcohol heating reflux treatment vary depending on the type of alcohol used. However, in general, the heating temperature is about 190 ° C., and the reflux time is in the range of 30 minutes to 6 hours. The end point of the reaction can be confirmed by changing the color of the solution to black. When it is confirmed that all of the Ru and Pt ions of the starting material have been reduced, the heat reflux treatment is terminated.
本発明において、Ｐｔ及びＲｕの塩又は錯体とＳの塩は、少なくとも一種離以上のアルコールからなる有機溶剤に溶解される。このアルコールは、アルコールのみからなる場合の他、水又はアルコール混和性の他の有機溶剤を含有するものであることもできる。アルコールは第一級アルコール又は第二級アルコールが好ましい。例えば、エチルアルコール、エチレングリコール、グリセリン、プロピレングリコール、イソアミルアルコール、ｎ-アミルアルコール、ｓｅｃ-ブチルアルコール、ｎ-ブチルアルコール、イソブチルアルコール、アリルアルコール、ｎ-プロピルアルコール、２-エトキシアルコール及び１，２-ヘキサデカンジオールなどが挙げられる。アルコール混和性の他の有機溶剤は例えば、エーテルジオキサン、テトラヒドロフラン、Ｎ-メチルピロリドン、アセトンなどが挙げられる。アルコールは二種類以上を併用することもできる。Ｐｔ及びＲｕの塩又は錯体及びＳの塩溶解用のアルコールは加熱還流処理に使用されるアルコールと同種のアルコールを使用することが好ましいが、異なる種類のアルコールも使用できる。 In the present invention, the salt or complex of Pt and Ru and the salt of S are dissolved in an organic solvent composed of at least one alcohol. The alcohol may contain water or other organic solvent miscible with alcohol in addition to the case of consisting of alcohol alone. The alcohol is preferably a primary alcohol or a secondary alcohol. For example, ethyl alcohol, ethylene glycol, glycerin, propylene glycol, isoamyl alcohol, n-amyl alcohol, sec-butyl alcohol, n-butyl alcohol, isobutyl alcohol, allyl alcohol, n-propyl alcohol, 2-ethoxy alcohol, and 1,2 -Hexadecanediol etc. are mentioned. Other organic solvents miscible with alcohol include ether dioxane, tetrahydrofuran, N-methylpyrrolidone, acetone and the like. Two or more types of alcohol can be used in combination. As the alcohol for dissolving the salt or complex of Pt and Ru and the salt of S, it is preferable to use the same type of alcohol as that used in the heating and refluxing process, but a different type of alcohol can also be used.
本発明のアルコール還元法において使用される担持用炭素粉末は、６０ｍ２／ｇ〜３０００ｍ２／ｇ程度の比表面積を有するものが好ましく、具体的には導電性カーボンブラック、アセチレンブラック、グラファイト、カーボンナノチユーブなどが好適である。担持用炭素粉末の使用量は一般的に、合金形成金属に対して、２〜２０倍の範囲内であることが好ましい。炭素粉末の使用量が２倍未満の場合、所期の効果が得られない。一方、炭素粉末の使用量が２０倍超の場合、目的とする効果が飽和し、不経済となる。 For supporting the carbon powder used in the alcohol reduction method of the present invention is preferably one having a specific surface area of about 60m 2 / g~3000m 2 / g, specifically conductive carbon black, acetylene black, graphite, carbon Nanotubes and the like are suitable. In general, the amount of the carbon powder for supporting is preferably within a range of 2 to 20 times the alloy-forming metal. If the amount of carbon powder used is less than twice, the desired effect cannot be obtained. On the other hand, when the amount of carbon powder used is more than 20 times, the intended effect is saturated and uneconomical.
ビス（アセチルアセトナト）白金(II)１．６９ミリモルとトリス（アセチルアセトナト）ルテニウム(III)１．６９ミリモルとチオ硫酸ナトリウム０．３４ミリモルをそれぞれ１００ｍｌのエチレングリコールに溶解させ、炭素基材（バルカンＸＣ−７２Ｒ）０．５ｇを分散させた１００ｍｌのエチレングリコール溶液を加えた。硫酸水溶液を滴下し、溶液をｐＨ３に調整した。窒素雰囲気下、２００℃でこの溶液を攪拌しながら還流し、ＰｔＲｕＳ合金微粒子を炭素基材上に担持させた。反応終了後、濾過、洗浄して乾燥させ触媒を得た。 1.69 mmol of bis (acetylacetonato) platinum (II), 1.69 mmol of tris (acetylacetonato) ruthenium (III) and 0.34 mmol of sodium thiosulfate were dissolved in 100 ml of ethylene glycol, respectively, 100 ml of ethylene glycol solution in which 0.5 g of (Vulcan XC-72R) was dispersed was added. An aqueous sulfuric acid solution was added dropwise to adjust the solution to pH 3. This solution was refluxed with stirring at 200 ° C. in a nitrogen atmosphere, and PtRuS alloy fine particles were supported on the carbon substrate. After completion of the reaction, the mixture was filtered, washed and dried to obtain a catalyst.
ビス（アセチルアセトナト）白金(II)１．６９ミリモルとトリス（アセチルアセトナト）ルテニウム(III)１．６９ミリモルをそれぞれ１００ｍｌのエチレングリコールに溶解させ、炭素基材（バルカンＸＣ−７２Ｒ）０．５ｇを分散させた１００ｍｌのエチレングリコール溶液を加えた。硫酸水溶液を滴下し、溶液をｐＨ３に調整した。窒素雰囲気下、２００℃でこの溶液を攪拌しながら還流し、ＰｔＲｕ合金微粒子を炭素基材上に担持させた。反応終了後、濾過、洗浄して乾燥させ触媒を得た。 1.69 mmol of bis (acetylacetonato) platinum (II) and 1.69 mmol of tris (acetylacetonato) ruthenium (III) were dissolved in 100 ml of ethylene glycol, respectively, and carbon base (Vulcan XC-72R) 0. 100 ml of ethylene glycol solution in which 5 g was dispersed was added. An aqueous sulfuric acid solution was added dropwise to adjust the solution to pH 3. This solution was refluxed with stirring at 200 ° C. in a nitrogen atmosphere, and PtRu alloy fine particles were supported on the carbon substrate. After completion of the reaction, the mixture was filtered, washed and dried to obtain a catalyst.
ビス（アセチルアセトナト）白金(II)１．６９ミリモルとトリス（アセチルアセトナト）ルテニウム(III)１．６９ミリモルとトリス（アセチルアセトナト）鉄(III)０．３４ミリモルとをそれぞれ１００ｍｌのエチレングリコールに溶解させ、炭素基材（バルカンＸＣ−７２Ｒ）０．５ｇを分散させた１００ｍｌのエチレングリコール溶液を加えた。硫酸水溶液を滴下し、溶液をｐＨ３に調整した。窒素雰囲気下、２００℃でこの溶液を攪拌しながら還流し、ＰｔＲｕＦｅ合金微粒子を炭素基材上に担持させた。反応終了後、濾過、洗浄して乾燥させ触媒を得た。 100 ml of ethylene each with 1.69 mmol of bis (acetylacetonato) platinum (II), 1.69 mmol of tris (acetylacetonato) ruthenium (III) and 0.34 mmol of tris (acetylacetonato) iron (III) 100 ml of an ethylene glycol solution in which 0.5 g of a carbon substrate (Vulcan XC-72R) was dispersed was added in a glycol. An aqueous sulfuric acid solution was added dropwise to adjust the solution to pH 3. This solution was refluxed with stirring at 200 ° C. in a nitrogen atmosphere, and PtRuFe alloy fine particles were supported on the carbon substrate. After completion of the reaction, the mixture was filtered, washed and dried to obtain a catalyst.
ビス（アセチルアセトナト）白金(II)１．６９ミリモルとトリス（アセチルアセトナト）ルテニウム(III)１．６９ミリモルとトリス（アセチルアセトナト）コバルト(III)０．３４ミリモルとをそれぞれ１００ｍｌのエチレングリコールに溶解させ、炭素基材（バルカンＸＣ−７２Ｒ）０．５ｇを分散させた１００ｍｌのエチレングリコール溶液を加えた。硫酸水溶液を滴下し、溶液をｐＨ３に調整した。窒素雰囲気下、２００℃でこの溶液を攪拌しながら還流し、ＰｔＲｕＣｏ合金微粒子を炭素基材上に担持させた。反応終了後、濾過、洗浄して乾燥させ触媒を得た。 100 ml of ethylene each with 1.69 mmol of bis (acetylacetonato) platinum (II), 1.69 mmol of tris (acetylacetonato) ruthenium (III) and 0.34 mmol of tris (acetylacetonato) cobalt (III) 100 ml of an ethylene glycol solution in which 0.5 g of a carbon substrate (Vulcan XC-72R) was dispersed was added in a glycol. An aqueous sulfuric acid solution was added dropwise to adjust the solution to pH 3. This solution was refluxed with stirring at 200 ° C. in a nitrogen atmosphere, and PtRuCo alloy fine particles were supported on the carbon substrate. After completion of the reaction, the mixture was filtered, washed and dried to obtain a catalyst.
ビス（アセチルアセトナト）白金(II)１．６９ミリモルとトリス（アセチルアセトナト）ルテニウム(III)１．６９ミリモルとビス（アセチルアセトナト）ニッケル(II)０．３４ミリモルとをそれぞれ１００ｍｌのエチレングリコールに溶解させ、炭素基材（バルカンＸＣ−７２Ｒ）０．５ｇを分散させた１００ｍｌのエチレングリコール溶液を加えた。硫酸水溶液を滴下し、溶液をｐＨ３に調整した。窒素雰囲気下、２００℃でこの溶液を攪拌しながら還流し、ＰｔＲｕＮｉ合金微粒子を炭素基材上に担持させた。反応終了後、濾過、洗浄して乾燥させ触媒を得た。 100 ml of ethylene each of 1.69 mmol of bis (acetylacetonato) platinum (II), 1.69 mmol of tris (acetylacetonato) ruthenium (III) and 0.34 mmol of bis (acetylacetonato) nickel (II) 100 ml of an ethylene glycol solution in which 0.5 g of a carbon substrate (Vulcan XC-72R) was dispersed was added in a glycol. An aqueous sulfuric acid solution was added dropwise to adjust the solution to pH 3. This solution was refluxed with stirring at 200 ° C. in a nitrogen atmosphere, and PtRuNi alloy fine particles were supported on the carbon substrate. After completion of the reaction, the mixture was filtered, washed and dried to obtain a catalyst.
ビス（アセチルアセトナト）白金(II)１．６９ミリモルとトリス（アセチルアセトナト）ルテニウム(III)１．６９ミリモルと塩化ビスマス(II)０．３４ミリモルとをそれぞれ１００ｍｌのエチレングリコールに溶解させ、炭素基材（バルカンＸＣ−７２Ｒ）０．５ｇを分散させた１００ｍｌのエチレングリコール溶液を加えた。硫酸水溶液を滴下し、溶液をｐＨ３に調整した。窒素雰囲気下、２００℃でこの溶液を攪拌しながら還流し、ＰｔＲｕＢｉ合金微粒子を炭素基材上に担持させた。反応終了後、濾過、洗浄して乾燥させ触媒を得た。 1.69 mmol of bis (acetylacetonato) platinum (II), 1.69 mmol of tris (acetylacetonato) ruthenium (III) and 0.34 mmol of bismuth (II) chloride are dissolved in 100 ml of ethylene glycol, respectively. 100 ml of ethylene glycol solution in which 0.5 g of carbon substrate (Vulcan XC-72R) was dispersed was added. An aqueous sulfuric acid solution was added dropwise to adjust the solution to pH 3. This solution was refluxed with stirring at 200 ° C. in a nitrogen atmosphere, and PtRuBi alloy fine particles were supported on the carbon substrate. After completion of the reaction, the mixture was filtered, washed and dried to obtain a catalyst.
実施例１で得られた炭素担持ＰｔＲｕＳ合金微粒子触媒と比較例１で得られた炭素担持ＰｔＲｕ合金微粒子触媒の表面を透過型電子顕微鏡で観察した。結果を図２に示す。（ａ）は炭素担持ＰｔＲｕ合金微粒子触媒の電顕写真であり、（ｂ）は炭素担持ＰｔＲｕＳ合金微粒子触媒の電顕写真である。電顕写真における黒色〜灰黒色部分は合金粒子であり、薄灰色又は灰白色部分は炭素担体である。（ａ）の電顕写真から明らかなように、ＰｔＲｕ合金微粒子は粒径が２ｎｍ程度のものも存在するが、同時に粒径が１０ｎｍ超のものや凝集塊も存在する。これに対し、（ｂ）の電顕写真によれば、本発明のＰｔＲｕＳ合金微粒子の場合、粒径は殆どが５ｎｍ未満であり、しかも粒子が均一に分散し、凝集塊は殆ど存在していない。 The surfaces of the carbon-supported PtRuS alloy fine particle catalyst obtained in Example 1 and the carbon-supported PtRu alloy fine particle catalyst obtained in Comparative Example 1 were observed with a transmission electron microscope. The results are shown in FIG. (A) is an electron micrograph of a carbon-supported PtRu alloy fine particle catalyst, and (b) is an electron micrograph of a carbon-supported PtRuS alloy fine particle catalyst. The black to grayish black portions in the electron micrographs are alloy particles, and the light gray or grayish white portions are carbon carriers. As is clear from the electron micrograph of (a), some PtRu alloy fine particles have a particle size of about 2 nm, but at the same time there are particles with a particle size exceeding 10 nm and aggregates. On the other hand, according to the electron micrograph of (b), in the case of the PtRuS alloy fine particles of the present invention, the particle size is almost less than 5 nm, the particles are uniformly dispersed, and there are almost no aggregates. .
（ａ）及び（ｂ）の電顕写真を元に、ＰｔＲｕ合金微粒子の粒径分布とＰｔＲｕＳ合金微粒子の粒径分布を測定した。結果を図３に示す。本発明のＰｔＲｕＳ合金微粒子の場合、粒径分布の中心値が２〜３ｎｍ付近に存在しバラツキが小さい。これに対して、比較例１のＰｔＲｕ合金微粒子の場合、粒径分布の中心値は６〜８ｎｍ付近に存在し、バラツキが大きい。 Based on the electron micrographs of (a) and (b), the particle size distribution of PtRu alloy fine particles and the particle size distribution of PtRuS alloy fine particles were measured. The results are shown in FIG. In the case of the PtRuS alloy fine particles of the present invention, the central value of the particle size distribution exists in the vicinity of 2 to 3 nm, and the variation is small. On the other hand, in the case of the PtRu alloy fine particles of Comparative Example 1, the central value of the particle size distribution exists in the vicinity of 6 to 8 nm, and the variation is large.
実施例１で得られた炭素担持ＰｔＲｕＳ合金微粒子触媒及び比較例１〜５でそれぞれ得られた炭素担持ＰｔＲｕ合金微粒子触媒について、メタノール酸化特性を測定した。測定方法を以下に示す。各炭素担持合金微粒子とイオン交換水とナフィオン溶液（アルドリッチ社製）を混合し、撹拌した後、その粘度を調整して、触媒層用インクとした。これをカーボンペーパー上に塗布し、乾燥後ホットプレスし、メタノール極を作製した。また、上記と同じ方法にて、白金担持カーボンを含む空気極を作製した。空気極室には酸化剤ガスとして空気、メタノール極室には、燃料としてメタノールと電解液である硫酸水溶液を流通させながら、メタノール酸化電流測定を行った。測定結果を図４に示す。 The methanol oxidation characteristics of the carbon-supported PtRuS alloy fine particle catalyst obtained in Example 1 and the carbon-supported PtRu alloy fine particle catalyst obtained in Comparative Examples 1 to 5 were measured. The measuring method is shown below. Each carbon-supported alloy fine particle, ion-exchanged water, and Nafion solution (manufactured by Aldrich) were mixed and stirred, and the viscosity was adjusted to obtain an ink for a catalyst layer. This was coated on carbon paper, dried and hot pressed to produce a methanol electrode. Moreover, the air electrode containing platinum carrying | support carbon was produced by the same method as the above. Methanol oxidation current measurement was performed while circulating air as an oxidant gas in the air electrode chamber and methanol and an aqueous sulfuric acid solution as an electrolyte in the methanol electrode chamber. The measurement results are shown in FIG.
図４に示された結果から、本発明の炭素担持ＰｔＲｕＳ合金微粒子触媒は、同様な条件で合成した炭素担持ＰｔＲｕ合金微粒子触媒（比較例１）に比べ、メタノール酸化電流が低い電位から流れ、活性の大幅な向上が確認できる。これは触媒の微粒化が活性の向上に寄与したものと考えられる。また、ＰｔＲｕにＳ以外の第三元素を添加した系において、その添加元素がＦｅ、Ｃｏ、Ｎｉからなる遷移金属の場合（比較例２〜４）、高分子固体導電膜のナフィオン膜由来の酸によって遷移金属が溶出し、メタノール酸化電流は殆ど流れなかった。また、添加元素がＢｉからなる遷移金属の場合（比較例５）、Ｂｉがメタノール酸化サイトを覆ってしまい、メタノール酸化活性が失われた。 From the results shown in FIG. 4, the carbon-supported PtRuS alloy fine particle catalyst of the present invention flows from a lower potential than the carbon-supported PtRu alloy fine particle catalyst (Comparative Example 1) synthesized under the same conditions. A significant improvement can be confirmed. This is considered that the atomization of the catalyst contributed to the improvement of the activity. Further, in a system in which a third element other than S is added to PtRu, when the added element is a transition metal composed of Fe, Co, and Ni (Comparative Examples 2 to 4), the acid derived from the Nafion film of the polymer solid conductive film Caused the transition metal to elute, and almost no methanol oxidation current flowed. Further, when the additive element was a transition metal made of Bi (Comparative Example 5), Bi covered the methanol oxidation site, and the methanol oxidation activity was lost.
本発明の炭素担持ＰｔＲｕＳ合金微粒子からなる燃料電池用触媒は、直接メタノール型燃料電池（ＤＭＦＣ）として特に有用であるが、固体高分子型燃料電池（ＰＥＦＣ）の触媒としても使用できる。 The fuel cell catalyst comprising the carbon-supported PtRuS alloy fine particles of the present invention is particularly useful as a direct methanol fuel cell (DMFC), but can also be used as a catalyst for a polymer electrolyte fuel cell (PEFC).
１ 本発明のＰｔＲｕＳ触媒微粒子
３ 炭素基材
５ ＰｔＲｕ粒子
７ Ｓ原子
1 PtRuS catalyst fine particles of the present invention 3 Carbon substrate 5 PtRu particles 7 S atoms
Claims (10)
ＰｔＲｕＳ
（前記式中、Ｓの含有率はＰｔＲｕの総モル数に対して、０．０１モル％〜５０モル％の範囲内である。）で示されることを特徴とする三元系合金。 The following general formula:
PtRuS
(In the above formula, the S content is in the range of 0.01 mol% to 50 mol% with respect to the total number of moles of PtRu).
ＰｔＲｕＳ
で示される三元系合金微粒子を担持したことを特徴とする燃料電池用触媒。 On the carbon substrate, the following general formula:
PtRuS
A fuel cell catalyst characterized by supporting ternary alloy fine particles represented by
(1)一種類以上のアルコールからなる有機溶剤中に炭素基材を分散させるステップと、
(2)前記炭素基材が分散されたアルコール系有機溶剤中に、Ｐｔの塩又は錯体と、Ｒｕの塩又は錯体と、Ｓ原子含有化合物を溶解させるステップと、
(3)炭素粉末が分散されたアルコール溶液のｐＨ値を２〜５の範囲に調整するステップと、
(4)不活性雰囲気中で、アルコールによる加熱還流を行うステップとからなり、
前記炭素基材上に、下記の一般式、
ＰｔＲｕＳ
で示される三元系合金微粒子を担持した燃料電池用触媒を生成することを特徴とする燃料電池用触媒の製造方法。 In the method for producing a fuel cell catalyst,
(1) dispersing a carbon base material in an organic solvent composed of one or more alcohols;
(2) dissolving a Pt salt or complex, a Ru salt or complex, and an S atom-containing compound in an alcohol-based organic solvent in which the carbon substrate is dispersed;
(3) adjusting the pH value of the alcohol solution in which the carbon powder is dispersed to a range of 2 to 5,
(4) a step of heating and refluxing with alcohol in an inert atmosphere,
On the carbon substrate, the following general formula:
PtRuS
A fuel cell catalyst carrying the ternary alloy fine particles represented by the formula (1) is produced.
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