JP3932335B2 - Integrated catalyst and method for producing the same - Google Patents
Integrated catalyst and method for producing the same Download PDFInfo
- Publication number
- JP3932335B2 JP3932335B2 JP07312999A JP7312999A JP3932335B2 JP 3932335 B2 JP3932335 B2 JP 3932335B2 JP 07312999 A JP07312999 A JP 07312999A JP 7312999 A JP7312999 A JP 7312999A JP 3932335 B2 JP3932335 B2 JP 3932335B2
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- aqueous solution
- metal
- hydroxide
- integrated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000003054 catalyst Substances 0.000 title claims description 284
- 238000004519 manufacturing process Methods 0.000 title claims description 22
- 239000007864 aqueous solution Substances 0.000 claims description 125
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 114
- 150000004706 metal oxides Chemical class 0.000 claims description 74
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 72
- 229910052751 metal Inorganic materials 0.000 claims description 61
- 239000002184 metal Substances 0.000 claims description 54
- 229910044991 metal oxide Inorganic materials 0.000 claims description 45
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 40
- 229910052697 platinum Inorganic materials 0.000 claims description 38
- 239000010931 gold Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 32
- 229910052737 gold Inorganic materials 0.000 claims description 30
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- -1 platinum cation Chemical class 0.000 claims description 21
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 20
- 229910052741 iridium Inorganic materials 0.000 claims description 20
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 20
- 150000002500 ions Chemical class 0.000 claims description 12
- IUJMNDNTFMJNEL-UHFFFAOYSA-K iridium(3+);trihydroxide Chemical compound [OH-].[OH-].[OH-].[Ir+3] IUJMNDNTFMJNEL-UHFFFAOYSA-K 0.000 claims description 11
- 229910021505 gold(III) hydroxide Inorganic materials 0.000 claims description 10
- WDZVNNYQBQRJRX-UHFFFAOYSA-K gold(iii) hydroxide Chemical compound O[Au](O)O WDZVNNYQBQRJRX-UHFFFAOYSA-K 0.000 claims description 10
- YXEUGTSPQFTXTR-UHFFFAOYSA-K lanthanum(3+);trihydroxide Chemical compound [OH-].[OH-].[OH-].[La+3] YXEUGTSPQFTXTR-UHFFFAOYSA-K 0.000 claims description 10
- 239000012702 metal oxide precursor Substances 0.000 claims description 8
- NFOHLBHARAZXFQ-UHFFFAOYSA-L platinum(2+);dihydroxide Chemical compound O[Pt]O NFOHLBHARAZXFQ-UHFFFAOYSA-L 0.000 claims description 8
- 239000002243 precursor Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 5
- 150000002344 gold compounds Chemical class 0.000 claims description 5
- 150000003058 platinum compounds Chemical class 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 4
- 230000002378 acidificating effect Effects 0.000 claims description 3
- 230000001939 inductive effect Effects 0.000 claims description 3
- 150000002503 iridium Chemical class 0.000 claims description 3
- 150000002603 lanthanum Chemical class 0.000 claims description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 44
- 230000000694 effects Effects 0.000 description 32
- 239000007789 gas Substances 0.000 description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 18
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 16
- 239000004202 carbamide Substances 0.000 description 16
- 239000010453 quartz Substances 0.000 description 16
- 239000000126 substance Substances 0.000 description 15
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 14
- 239000002131 composite material Substances 0.000 description 14
- 238000000354 decomposition reaction Methods 0.000 description 14
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 13
- 229910002091 carbon monoxide Inorganic materials 0.000 description 13
- 230000003197 catalytic effect Effects 0.000 description 12
- 239000011148 porous material Substances 0.000 description 12
- 239000002244 precipitate Substances 0.000 description 12
- 238000003756 stirring Methods 0.000 description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 229930195733 hydrocarbon Natural products 0.000 description 8
- 150000002430 hydrocarbons Chemical class 0.000 description 8
- 235000014413 iron hydroxide Nutrition 0.000 description 8
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 150000001412 amines Chemical class 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 229910000029 sodium carbonate Inorganic materials 0.000 description 7
- 238000006864 oxidative decomposition reaction Methods 0.000 description 6
- CVNKFOIOZXAFBO-UHFFFAOYSA-J tin(4+);tetrahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[Sn+4] CVNKFOIOZXAFBO-UHFFFAOYSA-J 0.000 description 6
- 150000004692 metal hydroxides Chemical group 0.000 description 5
- 230000000704 physical effect Effects 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 4
- LSDPWZHWYPCBBB-UHFFFAOYSA-N Methanethiol Chemical compound SC LSDPWZHWYPCBBB-UHFFFAOYSA-N 0.000 description 4
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 description 4
- 239000011294 coal tar pitch Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 229910003771 Gold(I) chloride Inorganic materials 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 235000002597 Solanum melongena Nutrition 0.000 description 3
- 244000061458 Solanum melongena Species 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 150000001299 aldehydes Chemical class 0.000 description 3
- 230000000295 complement effect Effects 0.000 description 3
- 238000004817 gas chromatography Methods 0.000 description 3
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000004056 waste incineration Methods 0.000 description 3
- ISPYQTSUDJAMAB-UHFFFAOYSA-N 2-chlorophenol Chemical compound OC1=CC=CC=C1Cl ISPYQTSUDJAMAB-UHFFFAOYSA-N 0.000 description 2
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000006004 Quartz sand Substances 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical class [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 229910021626 Tin(II) chloride Inorganic materials 0.000 description 2
- 238000000975 co-precipitation Methods 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- 150000004045 organic chlorine compounds Chemical class 0.000 description 2
- 238000010525 oxidative degradation reaction Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 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
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000011491 glass wool Substances 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 229910000457 iridium oxide Inorganic materials 0.000 description 1
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 229910017464 nitrogen compound Inorganic materials 0.000 description 1
- 150000002830 nitrogen compounds Chemical class 0.000 description 1
- RJIWZDNTCBHXAL-UHFFFAOYSA-N nitroxoline Chemical compound C1=CN=C2C(O)=CC=C([N+]([O-])=O)C2=C1 RJIWZDNTCBHXAL-UHFFFAOYSA-N 0.000 description 1
- 231100001143 noxa Toxicity 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000003057 platinum Chemical class 0.000 description 1
- CLSUSRZJUQMOHH-UHFFFAOYSA-L platinum dichloride Chemical compound Cl[Pt]Cl CLSUSRZJUQMOHH-UHFFFAOYSA-L 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- DANYXEHCMQHDNX-UHFFFAOYSA-K trichloroiridium Chemical compound Cl[Ir](Cl)Cl DANYXEHCMQHDNX-UHFFFAOYSA-K 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Description
【０００１】
【産業上の利用分野】
本発明は、触媒、特に集積化触媒に関する。
【０００２】
【従来の技術とその課題】
廃棄物焼却施設や自動車から排出される排気ガス中には、一酸化炭素、アルデヒド類、硫化物、炭化水素類、窒素化合物および有機塩素化合物などをはじめとする多種類の有害物質が含まれている。このため、廃棄物焼却施設等においては、触媒を用いて排気ガスを処理し、そこに含まれる有害物質の濃度を低減するよう試みられている。
【０００３】
ところで、触媒は、通常、特定の種類の有害物質に対してのみ特有の分解活性を示し、あらゆる種類の有害物質に対して普遍的な分解活性を示すものではない。また、有害物質のうちのある種のものは、特定の触媒を不活性化してしまうことさえある。例えば、二酸化ズスに白金元素を担持させた触媒は、高温領域において炭化水素類に対して高い酸化分解活性を示すが、低温領域においては一酸化炭素により被毒され、不活性化され易い。このため、多種類の有害物質を含む排気ガスを効果的に処理する必要がある場合は、有害物質の種類に応じた多種類の触媒を組合せて用いる方法、例えば、多種類の既存の触媒を均一に混合して用いる方法が考えられる。
【０００４】
しかし、多種類の触媒を混合したような場合は、たとえ触媒を均一に混合したとしても、種類の異なる触媒がμｍレベルで大きく離れて位置することになる。触媒による有害物質の分解は、触媒上での分子レベルの反応によるものであることから、分子レベルでみた場合に種類の異なる触媒が近接していない限り、多種類の有害物質を同時に効果的に分解するのは困難である。
【０００５】
本発明の目的は、種類の異なる複数の物質に対する活性を同時に効果的に発揮し得る触媒を実現することにある。
【０００９】
【課題を解決するための手段】
本発明の集積化触媒は、金元素が三酸化二鉄上に担持された第１触媒単位、白金元素が二酸化スズ上に担持された第２触媒単位およびイリジウム元素が酸化ランタン上に担持された第３触媒単位をそれぞれ多数含む触媒単位群からなり、第１触媒成分、第２触媒成分および第３触媒成分がナノメートルレベルで集合して触媒単位群を形成している。この集積化触媒では、例えば、触媒単位群が活性炭および活性炭素繊維のうちから選ばれた１種の担体上に配置されている。
【００１０】
本発明に係る集積化触媒の製造方法は、金属酸化物に対して特定の金属元素が組み合わされた触媒単位の複数種類がナノメートルレベルで多数集合した集積化触媒を製造するための方法であり、ナノメートルレベルで集積された、複数種類の金属酸化物を含む金属酸化物群を調製する第１の工程と、金属酸化物群に含まれる金属酸化物のそれぞれに対し、それに対応する金属元素を選択的に担持させる第２の工程とを含んでいる。
【００１１】
ここで、第２の工程は、複数種類の金属酸化物の等電点の差を利用して、金属酸化物群のうちの１種類の金属酸化物のみに対してそれに対応する金属元素のイオンを選択的に付着させる工程と、当該金属元素のイオンを金属元素に変換する工程とを含み、これらの工程からなる多段工程を金属酸化物群に含まれる金属酸化物の種類毎に繰り返している。
【００１２】
このような第２の工程において、金属元素のイオンを金属元素に変換する工程は、例えば、金属元素のイオンを金属元素の水酸化物に誘導する工程と、当該水酸化物を金属元素に変換する工程とを含んでいる。
【００１３】
なお、本発明に係る上述の集積化触媒の製造方法は、例えば、金属酸化物に変換可能な金属酸化物前駆体と、当該金属酸化物に対応する金属元素に変換可能な金属元素前駆体とを同時に析出させる工程と、金属酸化物前駆体および金属元素前駆体をそれぞれ金属酸化物および金属元素に変換する工程とを含む第３の工程をさらに含んでいてもよい。
【００１４】
この場合、第３の工程は、複数回繰り返されてもよい。また、上述の第２の工程における多段工程を繰り返す間に、第３の工程を少なくとも１回実施してもよい。
【００１５】
本発明に係る他の集積化触媒の製造方法は、金元素が三酸化二鉄上に担持された第１触媒単位、白金元素が二酸化スズ上に担持された第２触媒単位およびイリジウム元素が酸化ランタン上に担持された第３触媒単位をそれぞれ多数含む触媒単位群からなり、第１触媒成分、第２触媒成分および第３触媒成分がナノメートルレベルで集合して触媒単位群を形成している集積化触媒を製造するための方法である。この製造方法は、下記の工程を含んでいる。
【００１６】
◎ナノメートルレベルで集積された、三酸化二鉄と二酸化スズとを含む水溶液を調製する工程。
◎水溶液に白金化合物を溶解しかつ当該水溶液のｐＨを二酸化スズの等電点よりもアルカリ性側でありかつ三酸化二鉄の等電点より酸性側に設定して、白金化合物からの白金陽イオンを二酸化スズのみに選択的に付着させ、水溶液のｐＨを三酸化二鉄の等電点を越えない範囲でさらにアルカリ性側に調整して白金陽イオンから水酸化白金を誘導する工程。
◎水酸化白金を加熱処理して白金元素に変換する工程。
◎水溶液に金化合物を溶解しかつ水溶液のｐＨを二酸化スズの等電点と三酸化二鉄の等電点との間に設定して、金化合物からの金陰イオンを三酸化二鉄のみに選択的に付着させ、水溶液のｐＨをさらにアルカリ性側に調整して金陰イオンから水酸化金を誘導する工程。
◎水酸化金を加熱処理して金元素に変換する工程。
◎水溶液にランタン塩とイリジウム塩とを溶解した後、当該水溶液のｐＨを調整して、水溶液内に水酸化ランタンと水酸化イリジウムとを生成させる工程。
◎水酸化ランタンおよび水酸化イリジウムを加熱処理し、それぞれを酸化ランタンおよびイリジウム元素に変換する工程。
【００１７】
【発明の実施の形態】
本発明の集積化触媒は、多数の触媒単位を含んでいる。本発明において、触媒単位とは、それ自体で独自の触媒機能を発揮し得る単位を言う。例えば、金属元素、金属酸化物、および金属元素と金属酸化物との組合せ（以下、「複合触媒」と称する場合がある）などが本発明における触媒単位である。
【００１８】
ここで、金属元素は、例えば各種の排気ガス中に含まれる各種の有害物質のうちの少なくとも一成分を分解し得る触媒機能を発揮し得ることが知れられている公知のものであり、具体的には、金、白金、イリジウム、ルテニウム、ロジウム、パラジウムおよび銀を例示することができる。
【００１９】
また、金属酸化物は、上述の金属元素の担体または助触媒として金属元素と同様の触媒機能を発揮し得ることが知られている公知のものであり、具体的には、三酸化二鉄（Ｆｅ2Ｏ3）、二酸化スズ（ＳｎＯ2）および酸化ランタン（Ｌａ2Ｏ3）を例示することができる。その他にも、金属酸化物としては、アルミニウム、ケイ素、マグネシウム、チタン、バナジウム、マンガン、コバルト、ニッケル、銅、亜鉛、ジルコニウム、ニオブ、モリブデン、タングステン、セリウム、プラセオジムなどの金属元素の酸化物を挙げることができる。
【００２０】
さらに、金属元素と金属酸化物とが組合せられたもの、すなわち複合触媒は、例えば、上述の金属元素のうちの１つと、上述の金属酸化物のうちの１つとを組合せたものである。より具体的には、三酸化二鉄に金元素が担持されたもの、二酸化スズに白金が担持されたもの、および酸化ランタンにイリジウムが担持されたものなどを例示することができる。
【００２１】
複合触媒の触媒単位は、それを構成する金属元素と金属酸化物とが機能を分担し、しかも所要の触媒機能を互いに高め合い得る相乗効果を有するように金属元素と金属酸化物とが組合されているのが好ましい。例えば、炭化水素類に対する酸化分解において気相酸素の取り込みを容易に行うことができる二酸化スズに白金元素を担持させた触媒単位は、二酸化スズ単独または白金元素単独で達成できる炭化水素類に対する酸化分解活性に比べ、両者が組合されると、当該酸化分解活性が相乗的に高まる。また、ＮＯxと親和性を有する酸化ランタンにアミン類に対する分解活性を有するイリジウム元素を担持させた触媒単位は、酸化ランタン単独またはイリジウム元素単独でも同様にアミン類に対する分解活性を示し得るが、両者が組合されると、当該分解活性が相乗的に高まる。
【００２２】
本発明の集積化触媒は、上述のような触媒単位を複数種類含んでいる。触媒単位の種類の組合せは、特に限定されるものではなく、例えば、複数の種類の金属元素の組合せ、複数の種類の金属酸化物の組合せ、複数の種類の複合触媒の組合せ、並びに金属元素、金属酸化物および複合触媒のうちの２種以上の組合せなどである。なお、本発明では、所要の触媒機能を最も効果的に発揮し得ることから、複数の種類の触媒単位のそれぞれが、いずれも複合触媒であるもの、すなわち、金属酸化物と金属元素との組合せからなるものが好ましい。
【００２３】
触媒の機能的観点からの触媒単位の組合せは、本発明の集積化触媒の用途、換言すると、本発明の集積化触媒に求められる触媒機能に応じて適宜設定することができ、特に限定されるものではないが、通常は、各触媒単位が他の触媒単位とは異なる独自の触媒機能を有し、少なくとも１種の触媒単位が他の触媒単位のうちの少なくとも１種の触媒単位の触媒機能を補完可能なように設定されているのが好ましい。因みに、ここで言う「触媒機能の補完」とは、ある触媒単位が他の触媒単位の触媒活性を維持しまたは促進するようなことを言う。
【００２４】
例えば、炭化水素類に対する酸化分解活性を示す、二酸化スズに白金元素を担持させた触媒単位、およびＮＯxと親和性を示す酸化ランタンにアミン類に対する分解活性を示すイリジウム元素を担持させた触媒単位のうちの少なくとも１種を用いる場合、これらの触媒単位は炭化水素類またはアミン類を分解したときに生成する一酸化炭素により自らが被毒されて触媒活性を喪失し易いので、それらの触媒単位の触媒活性を維持させるために、一酸化炭素に対する分解活性を示す、三酸化二鉄に金元素を担持させた触媒単位を組合せるのが好ましい。
【００２５】
本発明の集積化触媒は、上述のような複数の種類の触媒単位を多数含む触媒単位群からなる。ここで、触媒単位群は、複数の種類の触媒単位の多数を単に混合しただけのものではなく、複数の種類の触媒単位の多数が原子や分子の数倍の寸法であるナノメートル以下のレベルで集合して一体化したものである。図１に、このような本発明の集積化触媒の一形態の概念図を示す。図において、集積化触媒１は、３種類の触媒単位ａ、ｂおよびｃのそれぞれを多数含む触媒単位群Ｕからなり、触媒単位ａ、ｂおよびｃはランダムに層状に積層されている。また、図２に、集積化触媒の他の形態の概念図を示す。図において、集積化触媒２は、図１に示す形態のものと同様に３種類の触媒単位ａ、ｂおよびｃのそれぞれを多数含む触媒単位群Ｕからなり、触媒単位ａ、ｂおよびｃは単層状にランダムに配列されている。
【００２６】
なお、上述の各形態の集積化触媒１、２は、担体Ｓ上に配置されていてもよい。ここで用いられる担体は、触媒単位群Ｕを担持することができるものであれば特に限定されるものではないが、例えば、活性炭、活性炭素繊維、アルミナおよびシリカなどを挙げることができる。このうち、本発明では、活性炭または活性炭素繊維を担体として用いるのが好ましい。活性炭および活性炭素繊維は、直径が数十オングストロームに達する細孔を多数有しており、その結果、比表面積が他の担体に比べて格段に大きいため、触媒単位群を他の担体に比べて多く担持することができる。また、その特有の細孔構造のために、微粒子状の有害物質やファンデルワールス半径が大きな分子の有害物質を細孔内に効果的に吸着することができ、そのような有害物質をその細孔内に担持された触媒単位群により効果的に分解することもできる。したがって、担体として活性炭または活性炭素繊維を用いた場合は、本発明の集積化触媒による効果をより高めることができる。
【００２７】
本発明の集積化触媒として好ましいものは、複数の種類のそれぞれの触媒単位が金属酸化物と金属元素との組合せからなる複合触媒であり、しかも、このような触媒単位のうちの少なくとも１種が他の触媒単位のうちの少なくとも１種の触媒機能を補完可能なように選択されたものである。この場合、触媒単位のうちの少なくとも１種は、上述のように金属酸化物と金属元素とが触媒機能を相乗的に高め得る組合せに設定されているのが特に好ましい。
【００２８】
このような集積化触媒の一例として、金元素が三酸化二鉄上に担持された第１触媒単位、白金元素が二酸化スズ上に担持された第２触媒単位およびイリジウム元素が酸化ランタン上に担持された第３触媒単位の３種類の触媒単位をそれぞれ多数含み、これらの各触媒単位がナノメートルレベルで集合して触媒単位群を形成しているものを挙げることができる。なお、この触媒単位群は、活性炭または活性炭素繊維からなる担体上に配置されていてもよい。
【００２９】
このような集積化触媒において、第１触媒成分は、一酸化炭素およびアルデヒド類に対して優れた低温酸化分解活性を示す。特に、一酸化炭素に対しては、−７０℃でも優れた酸化分解活性を示す。また、第２触媒成分は、高温領域において炭化水素類などに対して優れた酸化分解活性を示す。さらに、第３触媒成分は、アミン類に対して優れた分解活性を示す。このため、この集積化触媒は、一酸化炭素、アルデヒド類、炭化水素類、アミン類、メルカプタン類およびダイオキシンなどの有機塩素化合物を含む排気ガスの処理用触媒として用いられた場合、排気ガス中に含まれるこれらの有害物質の濃度を比較的低温で同時に効果的に低減させることができ、しかもその機能を長期間持続することができる。
【００３０】
特に、この集積化触媒は、第１触媒単位が第２触媒単位および第３触媒単位の補完的機能を発揮し得る。すなわち、第２触媒単位および第３触媒単位は、それぞれ炭化水素類およびアミン類を分解した際に自らが生成する一酸化炭素および排気ガス中に含まれる一酸化炭素により被毒され、活性が著しく低下する場合があるが、この一酸化炭素は第１触媒単位により分解され得るので、第２触媒単位および第３触媒単位の活性は維持され得る。
【００３１】
つまり、この集積化触媒は、第１触媒単位、第２触媒単位および第３触媒単位を単に均一に混合しただけのものとは異なり、これらの触媒単位がナノメートルレベルで集合して一体化しているため（すなわち、各触媒単位がナノメートルレベルで近接しながら集合しているため）、第２触媒単位および第３触媒単位において分子レベルの反応で生成した一酸化炭素をそれらの触媒単位にナノメートルレベルで近接して位置する第１触媒成分により速やかに分解し得る。
【００３２】
以上の結果、この集積化触媒は、所要の触媒機能を効果的に、しかも長期間持続的に発揮し得る。
このような本発明の集積化触媒は、上述のような機能を発揮し得るため、例えば、ごみ焼却施設や各種の産業プラントから排出される排気ガスの処理用触媒、空気清浄機用触媒および燃料電池用触媒などとして利用することができる。
【００３３】
本発明の集積化触媒は、例えば、共沈殿法などの公知の手法により、水溶液中で各種の金属元素や金属酸化物を同時に析出させると製造することができる。但し、集積化触媒のうち、金属元素と金属酸化物とが組み合わされた触媒単位の複数種類がナノメートルレベルで多数集合したものは、特定の金属元素と特定の金属酸化物とが対になるよう組合せる必要があるので、通常の共沈殿法による手法では製造が困難である。そこで、このような集積化触媒を製造するための方法を以下に説明する。
【００３４】
ここでは、金元素が三酸化二鉄に担持された触媒単位の多数と白金元素が二酸化スズに担持された触媒単位の多数とを含む触媒単位群からなる集積化触媒を例とし、その製造方法を工程毎に説明する。
【００３５】
第１の工程
この工程では、複数種類の金属酸化物、すなわち三酸化二鉄と二酸化スズとがナノメートルレベルで集積された金属酸化物群を調整する。ここでは、先ず、鉄塩およびスズ塩（例えば、共に硝酸塩）を含む水溶液を調製し、この水溶液のｐＨをアルカリ性側に徐々に調整することにより水酸化鉄および水酸化スズを調製する。ここで、水溶液のｐＨをアルカリ性側に調整するための方法としては、例えば、▲１▼予め水溶液中に尿素を溶解しておき、この水溶液を７０℃程度に加熱する方法、および▲２▼水溶液に炭酸ナトリウム水溶液または水酸化ナトリウム水溶液を徐々に滴下する方法などを採用することができる。
【００３６】
▲１▼の方法による場合は、水溶液を加熱すると、尿素が緩やかに分解してＮＨ4 +イオンとＯＨ-イオンとが生成する。これにより、水溶液のｐＨが徐々にアルカリ性側に変化し、ｐＨ値がある値よりもアルカリ性側になると、水溶液中に水に不溶の水酸化鉄および水酸化スズがナノメートルレベルで集合しながら析出し、水溶液中に沈殿する。これにより得られる金属水酸化物群を酸素含有雰囲気中で熱処理すると、当該金属水酸化物群は目的とする金属酸化物群、すなわち三酸化二鉄と二酸化スズとを含む金属酸化物群に変換される。
【００３７】
一方、▲２▼の方法による場合は、金属塩、すなわち上述の鉄塩およびスズ塩を含む水溶液を攪拌しながら炭酸ナトリウム水溶液または水酸化ナトリウム水溶液を徐々に滴下する。これにより、水溶液のｐＨが徐々にアルカリ性側に変化し、ｐＨ値がある値よりもアルカリ性側になると、水溶液中に水に不溶の水酸化鉄および水酸化スズがナノメートルレベルで集合しながら析出し、水溶液中に沈殿する。これにより得られる金属水酸化物群を酸素含有雰囲気中で熱処理すると、金属水酸化物群は目的とする金属酸化物群、すなわち三酸化二鉄と二酸化スズとを含む金属酸化物群に変換される。
【００３８】
なお、この工程では、上述のように水溶液中に複数の金属塩を同時に添加して、それらに対応する複数の金属酸化物を同時に生成させるようにしてもよいし、金属塩を１種類ずつ添加して、それに対応する金属酸化物を１種類ずつ順に生成させるようにしてもよい。
【００３９】
また、触媒単位群が担体上に配置された集積化触媒を製造する場合は、この工程において、水溶液中に予め上述の担体を配置しておく。このようにすると、上述の金属水酸化物群が担体上に沈殿するので、金属酸化物群を担体上に生成させる（担持させる）ことができる。
【００４０】
第２の工程
この工程では、第１の工程で得られた金属酸化物群に含まれるそれぞれの金属酸化物、すなわち、三酸化二鉄および二酸化スズのそれぞれに対し、対応する金属元素、すなわち金元素および白金元素を選択的に担持させる。
【００４１】
ここでは、三酸化二鉄と二酸化スズとの等電点の差を利用し、両者に対して対応する金属元素を選択的に担持させる。図３に、三酸化二鉄および二酸化スズの水溶液中におけるイオン吸着密度とｐＨとの関係を示す。図に示すように、二酸化スズの等電点（ｐＨ）は４．５であり、三酸化二鉄の等電点は８．０である。このため、水溶液のｐＨが４．５未満の場合、二酸化スズおよび三酸化二鉄の表面はいずれも正電荷を帯びることになる。また、水溶液のｐＨが４．５〜８．０の範囲では、二酸化スズの表面は負電荷を帯び、三酸化二鉄の表面は正電荷を帯びることになる。
【００４２】
この工程では、上述のような三酸化二鉄と二酸化スズとの等電点の差を利用して、これらの金属酸化物に対して対応する金属元素を選択的に担持させることができる。具体的には、先ず、三酸化二鉄と二酸化スズとを含む水溶液中に白金化合物（例えば白金塩、より具体的には例えば塩化白金）を添加し、水溶液のｐＨを４．５以上でありかつ三酸化二鉄の等電点よりも酸性側に設定する。この結果、水溶液中で生成するカチオン性の白金イオン（Ｐｔ4+）は、そのｐＨで表面が負電荷を帯びている二酸化スズの表面に引き寄せられ、正電荷を帯びている三酸化二鉄に対して反発することになる。
【００４３】
この状態で水溶液のｐＨをさらにアルカリ性側に設定すると、白金イオンは水酸化白金（Ｐｔ（ＯＨ）4・２Ｈ2Ｏ）となり、二酸化スズ上のみに選択的に析出する。その後、水溶液から金属酸化物群を取り出して熱処理すると、水酸化白金は白金元素に変換され、白金元素を担持した二酸化スズと三酸化二鉄とを含む金属酸化物群が得られる。
【００４４】
次に、この金属酸化物群の水溶液を再度調製し、それに金化合物（例えば金元素を含む酸、より具体的には例えば塩化金酸）を添加する。そして、その水溶液のｐＨを４．５以上でありかつ三酸化二鉄の等電点よりも酸性側に設定すると、水溶液中で生成するアニオン性の金イオン（例えば、ＡｕＣｌ4 -）は当該ｐＨ領域で表面が正電荷を帯びている三酸化二鉄に引き寄せられ、表面が負電荷を帯びている二酸化スズに対して反発することになる。この状態で水溶液のｐＨをさらにアルカリ性側に設定すると、金イオンは水酸化金（Ａｕ（ＯＨ）3）となり、三酸化二鉄上のみに選択的に析出する。その後、水溶液から金属酸化物群を取り出して熱処理すると、水酸化金は金元素に変換される。この結果、白金元素を担持した二酸化スズからなる触媒単位と金元素を担持した三酸化二鉄からなる触媒単位とを多数含む触媒単位群、すなわち目的とする集積化触媒が得られる。なお、上述の第１の工程において、金属酸化物群を担体上に生成させた場合、この集積化触媒は担体上に形成されることになる。
【００４５】
第３の工程
白金元素を担持した二酸化スズからなる触媒単位と金元素を担持した三酸化二鉄からなる触媒単位とに加えて、例えばイリジウム元素を担持した酸化ランタンからなる触媒単位をさらに含む触媒単位群からなる集積化触媒を製造する場合は、上述のような第１の工程および第２の工程を経て得られた集積化触媒に対し、以下に説明する第３の工程をさらに適用する。
【００４６】
この工程では、先ず、上述の第２の工程により得られた集積化触媒に対し、酸化ランタンに変換可能な金属酸化物前駆体とイリジウム元素に変換可能な金属元素前駆体とを同時に析出させる。なお、ここで言う金属酸化物前駆体および金属元素前駆体は、例えば、それぞれ水酸化ランタンおよび水酸化イリジウムである。
【００４７】
ここでは、通常、金属酸化物前駆体を形成するための金属の塩（この例の場合はランタンの塩、より具体的には例えば硝酸ランタン）と金属元素前駆体を形成するための金属の塩（この例の場合はイリジウムの塩、より具体的には例えば塩化イリジウム）とを含む水溶液を調製し、これに上述の第２の工程により得られた集積化触媒を添加する。そして、当該水溶液のｐＨを徐々にアルカリ性側に調整し、水酸化ランタン（金属酸化物前駆体）と水酸化イリジウム（金属元素前駆体）とを同時に沈殿させる。この際、水酸化ランタンと水酸化イリジウムとは、ナノメートルレベルで互いに集合しながら析出して沈殿し、同時に第２の工程で得られた集積化触媒に対してナノメートルレベルで集積する。
【００４８】
なお、水溶液のｐＨを調整するための方法としては、上述の第１の工程で採用可能な方法と同様の方法、すなわち、水溶液中に尿素を添加して７０℃程度に加熱する方法および水溶液に対して炭酸ナトリウム水溶液または水酸化ナトリウム水溶液を徐々に滴下する方法を採用することができる。
【００４９】
次に、水酸化ランタンと水酸化イリジウムとが追加的に集積した集積化触媒を水溶液から取り出し、これを空気中で熱処理する。これにより、水酸化ランタンおよび水酸化イリジウムは、同時にそれぞれ酸化ランタンおよびイリジウム元素に変換され、イリジウム元素を担持した酸化ランタンからなる新たな触媒単位が生成する。これにより、白金元素を担持した二酸化スズからなる触媒単位、金元素を担持した三酸化二鉄からなる触媒単位およびイリジウム元素を担持した酸化ランタンからなる触媒単位の３種類の触媒単位を含む触媒単位群からなる集積化触媒が得られる。
【００５０】
なお、上述のような最終段階での熱処理工程において、その際の条件により水酸化イリジウムが酸化イリジウムに変換されてしまう場合があるが、この場合はそれを適宜還元雰囲気下で熱処理すると、イリジウム元素に変換することができる。
【００５１】
本発明に係る上述の製造方法は、上述のような例に係る集積化触媒以外の他の集積化触媒、すなわち、金属元素が金属酸化物に担持された触媒単位の複数種類からなる他の集積化触媒を製造する場合にも適用することができる。この場合、上述の第１の工程において３種類以上の金属酸化物を含む金属酸化物群を形成し、それに対して第２の工程を触媒単位の種類に応じて３回以上繰り返してもよい。また、触媒単位の種類に応じ、上述の第３の工程を２回以上繰り返してもよい。さらに、上述の製造方法では、必ずしも第１の工程と第２の工程とを完了してから第３の工程を実施する必要はなく、第３の工程を実施してから第１および第２の工程を実施してもよいし、第１の工程で得られた金属酸化物群に含まれる金属酸化物に対して第２の工程を繰り返し適用する間に適宜第３の工程を１回または２回以上挿入してもよい。
【００５２】
【実施例】
実施例１
ナス型フラスコに５００ｍｌの水を加え、これに１０ｇのコールタールピッチ系活性炭素繊維（平均繊維径＝１４．０μｍ、ＢＥＴ比表面積＝１，９２０ｍ2／ｇ、平均細孔径＝１９．０１オングストローム）を浸した。この際、活性炭素繊維の細孔内にも水を浸入させるため、ナス型フラスコ内を約１０分間真空脱気処理した。
【００５３】
次に、ナス型フラスコ内の活性炭素繊維を水と共に蓋付き円筒型瓶に移し、これに０．００６モルのＦｅ（ＮＯ3）3・９Ｈ2Ｏ、０．００６モルのＳｎＣｌ4および０．０３６モルの尿素を加えて溶解し、５００ｍｌの水溶液を得た。そして、この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。この際、水溶液中の尿素が加水分解してＯＨ-イオンが生成し、水溶液のｐＨが徐々にアルカリ性側に移行した。この結果、水溶液中の活性炭素繊維には、水酸化鉄（Ｆｅ（ＯＨ）3）と水酸化スズ（Ｓｎ（ＯＨ）4）が析出して沈殿した。
【００５４】
活性炭素繊維を水溶液から取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この活性炭素繊維をガス流通式石英管に充填し、この石英管に２容量％の酸素と９８容量％の窒素とを含む混合ガスを活性炭素繊維約１ｇに対して２５０ｍｌ／分の流速で流しながら活性炭素繊維を３００℃で３時間焼成した。この結果、水酸化鉄と水酸化スズとが酸化物に変換され、三酸化二鉄と二酸化スズとを担持した活性炭素繊維が得られた。
【００５５】
次に、三酸化二鉄と二酸化スズとを担持した活性炭素繊維１０ｇをナス型フラスコ内の水５００ｍｌに浸し、上述と同様に脱気処理した。その後、当該活性炭素繊維を水と共に蓋付き円筒型瓶に移し、これに０．０００３モルのＰｔＣｌ4を加えて５００ｍｌの水溶液を調製した。この水溶液のｐＨは１．８であった。
【００５６】
水溶液のｐＨが６．０になるまで攪拌しながら５％の炭酸ナトリウム水溶液を緩やかに滴下し、このｐＨを維持しながら水溶液を２時間熟成した。この過程では、水溶液のｐＨが二酸化スズの等電点以上、すなわち４．５以上になると、水溶液中の白金イオン（Ｐｔ4+）が負電荷を帯びた二酸化スズの表面のみに選択的に移行し、ｐＨが６．０になったときに白金イオンが水酸化白金（Ｐｔ（ＯＨ）4・２Ｈ2Ｏ）に変化して二酸化スズの表面にのみ析出して沈殿した。
【００５７】
以上のようにして処理された活性炭素繊維を水溶液から取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この活性炭素繊維をガス流通式石英管に充填し、この石英管に２容量％の酸素と９８容量％の窒素とを含む混合ガスを活性炭素繊維約１ｇに対して２５０ｍｌ／分の流速で流しながら活性炭素繊維を３００℃で３時間焼成した。続けて、この石英管に水素ガスを活性炭素繊維約１ｇに対して１００ｍｌ／分の流速で流しながら活性炭素繊維を２００℃で３時間還元処理した。この結果、白金元素を担持した二酸化スズからなる触媒単位と、三酸化二鉄とを担持した活性炭素繊維が得られた。
【００５８】
次に、白金元素を担持した二酸化スズからなる触媒単位と、三酸化二鉄とを担持した活性炭素繊維１０ｇをナス型フラスコ内の水５００ｍｌに浸し、上述と同様に脱気処理した。その後、当該活性炭素繊維を水と共に蓋付き円筒型瓶に移し、これに０．０００３モルのＨＡｕＣｌ4・４Ｈ2Ｏを加えて５００ｍｌの水溶液を調製した。この水溶液のｐＨは２．８であった。
【００５９】
水溶液のｐＨが７．０になるまで攪拌しながら５％の炭酸ナトリウム水溶液を緩やかに滴下し、このｐＨを維持しながら水溶液を５時間熟成した。この過程では、水溶液のｐＨが二酸化スズの等電点以上、すなわち４．５以上になると、水溶液中の金イオン（ＡｕＣｌ4-）が正電荷を帯びた三酸化二鉄の表面のみに選択的に移行し、ｐＨが７．０になったときに当該金イオンが水酸化金（Ａｕ（ＯＨ）3）に変化して三酸化二鉄の表面にのみ析出して沈殿した。
【００６０】
以上のようにして処理された活性炭素繊維を水溶液から取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この活性炭素繊維をガス流通式石英管に充填し、この石英管に２容量％の酸素と９８容量％の窒素とを含む混合ガスを活性炭素繊維約１ｇに対して２５０ｍｌ／分の流速で流しながら活性炭素繊維を３００℃で３時間焼成した。この結果、白金元素を担持した二酸化スズからなる触媒単位および金元素を担持した三酸化二鉄からなる触媒単位の２つの触媒単位を担持した活性炭素繊維、すなわち集積化触媒が得られた。得られた集積化触媒の組成および物理的性状は表１に示す通りである。
【００６１】
実施例２
実施例１で得られた集積化触媒１０ｇをナス型フラスコ内の５００ｍｌの水中に浸し、実施例１の場合と同様にして脱気処理した後、集積化触媒を水と共に蓋付き円筒型瓶に移した。これに０．００６モルのＬａ（ＮＯ3）3・６Ｈ2Ｏ、０．０００３モルのＩｒＣｌ3および０．０１９モルの尿素を添加し、５００ｍｌの水溶液を調製した。そして、この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。この際、水溶液中の尿素が加水分解してＯＨ-イオンが生成し、水溶液のｐＨが徐々にアルカリ性側に移行した。この結果、水溶液中の集積化触媒を構成する活性炭素繊維には、水酸化イリジウム（Ｉｒ（ＯＨ）3）と水酸化ランタン（Ｌａ（ＯＨ）3）が析出して沈殿した。
【００６２】
以上のようにして処理された集積化触媒を水溶液から取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この集積化触媒をガス流通式石英管に充填し、この石英管に空気を集積化触媒約１ｇに対して２５０ｍｌ／分の流速で流しながら集積化触媒を３００℃で３時間焼成した。続けて、この石英管に水素ガスを集積化触媒約１ｇに対して１００ｍｌ／分の流速で流しながら集積化触媒を２００℃で３時間還元処理した。この結果、白金元素を担持した二酸化スズからなる触媒単位、金元素を担持した三酸化二鉄からなる触媒単位に加え、さらにイリジウム元素を担持した酸化ランタンからなる触媒単位が活性炭素繊維上に集積された集積化触媒が得られた。得られた集積化触媒の組成および物理的性状は表１に示す通りである。
【００６３】
実施例３
５００ｍｌの水を仕込んだ蓋付き円筒型瓶に０．６モルのＦｅ（ＮＯ3）3・９Ｈ2Ｏ、０．６モルのＳｎＣｌ4および３．６モルの尿素を加えて溶解し、水溶液を得た。そして、この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。この際、水溶液中の尿素が加水分解してＯＨ-イオンが生成し、水溶液のｐＨが徐々にアルカリ性側に移行した。この結果、水溶液中の活性炭素繊維には、水酸化鉄（Ｆｅ（ＯＨ）3）と水酸化スズ（Ｓｎ（ＯＨ）4）とが析出して沈殿した。
【００６４】
この水溶液を濾過して沈殿を採取し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。その後、沈殿をガス流通式石英管に充填し、この石英管に空気を沈殿約１ｇに対して２５０ｍｌ／分の流速で流しながら沈殿を３００℃で３時間焼成した。この結果、三酸化二鉄と二酸化スズとからなる金属酸化物群が得られた。
【００６５】
次に、金属酸化物群１０ｇをナス型フラスコ内の水５００ｍｌに浸し、上述と同様に脱気処理した。その後、当該金属酸化物群を水と共に蓋付き円筒型瓶に移し、これに０．０３モルのＰｔＣｌ4を加えて５００ｍｌの水溶液を調製した。この水溶液のｐＨは１．８であった。
【００６６】
水溶液のｐＨが６．０になるまで攪拌しながら５％の炭酸ナトリウム水溶液を緩やかに滴下し、このｐＨを維持しながら水溶液を５時間熟成した。この過程では、水溶液のｐＨが二酸化スズの等電点以上、すなわち４．５以上になると、水溶液中の白金イオン（Ｐｔ4+）が負電荷を帯びた二酸化スズの表面のみに選択的に移行し、ｐＨが６．０になったときに白金イオンが水酸化白金（Ｐｔ（ＯＨ）4）に変化して二酸化スズの表面にのみ析出して沈殿した。
【００６７】
以上のようにして処理された金属酸化物群を水溶液から取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この金属酸化物群をガス流通式石英管に充填し、この石英管に空気を金属酸化物群約１ｇに対して２５０ｍｌ／分の流速で流しながら金属酸化物群を３００℃で３時間焼成した。続けて、この石英管に水素ガスを金属酸化物群約１ｇに対して１００ｍｌ／分の流速で流しながら金属酸化物群を２００℃で３時間還元処理した。この結果、白金元素を担持した二酸化スズからなる触媒単位と、三酸化二鉄との複合物が得られた。
【００６８】
次に、複合物１０ｇをナス型フラスコ内の水５００ｍｌに浸し、上述と同様に脱気処理した。その後、当該複合物を水と共に蓋付き円筒型瓶に移し、これに０．０３モルのＨＡｕＣｌ4・４Ｈ2Ｏを加えて５００ｍｌの水溶液を調製した。この水溶液のｐＨは２．８であった。
【００６９】
水溶液のｐＨが７．０になるまで攪拌しながら５％の炭酸ナトリウム水溶液を緩やかに滴下し、このｐＨを維持しながら水溶液を５時間熟成した。この過程では、水溶液のｐＨが二酸化スズの等電点以上、すなわち４．５以上になると、水溶液中の金イオン（ＡｕＣｌ4-）が正電荷を帯びた三酸化二鉄の表面のみに選択的に移行し、ｐＨが７．０になったときに当該金イオンが水酸化金（Ａｕ（ＯＨ）3）に変化して三酸化二鉄の表面にのみ析出して沈殿した。
【００７０】
以上のようにして処理された複合物を水溶液から取り出して濾過し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この複合物をガス流通式石英管に充填し、この石英管に空気を複合物約１ｇに対して２５０ｍｌ／分の流速で流しながら複合物を３００℃で３時間焼成した。この結果、白金元素を担持した二酸化スズからなる触媒単位および金元素を担持した三酸化二鉄からなる触媒単位の２つの触媒単位からなる集積化触媒が得られた。得られた集積化触媒の組成および物理的性状は表１に示す通りである。
【００７１】
比較例１
下記のようにして得られた触媒成分１、触媒成分２および触媒成分３を１：１：１の割合で均一に混合し、混合触媒を得た。得られた混合触媒の組成および物理的性状は表１に示す通りである。
【００７２】
（触媒成分１）
ナス型フラスコに５００ｍｌの水を加え、これに１０ｇのコールタールピッチ系活性炭素繊維（平均繊維径＝１４．０μｍ、ＢＥＴ比表面積＝１，９２０ｍ2／ｇ、平均細孔径＝１９．０１オングストローム）を浸した。この際、活性炭素繊維の細孔内にも水を浸入させるため、ナス型フラスコ内を約１０分間真空脱気処理した。
【００７３】
次に、ナス型フラスコ内の活性炭素繊維を水と共に蓋付き円筒型瓶に移し、これに０．００６モルのＦｅ（ＮＯ3）3・９Ｈ2Ｏ、０．０００３モルのＨＡｕＣｌ4・４Ｈ2Ｏおよび０．０５７モルの尿素を加えて溶解し、５００ｍｌの水溶液を得た。そして、この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。この際、水溶液中の尿素が加水分解してＯＨ-イオンが生成し、水溶液のｐＨが徐々にアルカリ性側に移行した。この結果、水溶液中の活性炭素繊維には、水酸化鉄（Ｆｅ（ＯＨ）3）と水酸化金（Ａｕ（ＯＨ）3）が析出して沈殿した。
【００７４】
活性炭素繊維を水溶液から取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この活性炭素繊維をガス流通式石英管に充填し、この石英管に２容量％の酸素と９８容量％の窒素とを含む混合ガスを活性炭素繊維約１ｇに対して２５０ｍｌ／分の流速で流しながら活性炭素繊維を３００℃で３時間焼成した。これにより、金元素と三酸化二鉄とを担持した活性炭素繊維（触媒成分１）が得られた。
【００７５】
（触媒成分２）
ナス型フラスコに５００ｍｌの水を加え、これに１０ｇのコールタールピッチ系活性炭素繊維（平均繊維径＝１４．０μｍ、ＢＥＴ比表面積＝１，９２０ｍ2／ｇ、平均細孔径＝１９．０１オングストローム）を浸した。この際、活性炭素繊維の細孔内にも水を浸入させるため、ナス型フラスコ内を約１０分間真空脱気処理した。
【００７６】
次に、ナス型フラスコ内の活性炭素繊維を水と共に蓋付き円筒型瓶に移し、これに０．００６モルのＳｎＣｌ4、０．０００３モルのＰｔＣｌ4および０．０５７モルの尿素を加えて溶解し、５００ｍｌの水溶液を得た。そして、この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。以下、触媒成分１の場合と同様に操作したところ、白金元素と二酸化スズとを担持した活性炭素繊維（触媒成分２）が得られた。
【００７７】
（触媒成分３）
ナス型フラスコに５００ｍｌの水を加え、これに１０ｇのコールタールピッチ系活性炭素繊維（平均繊維径＝１４．０μｍ、ＢＥＴ比表面積＝１，９２０ｍ2／ｇ、平均細孔径＝１９．０１オングストローム）を浸した。この際、活性炭素繊維の細孔内にも水を浸入させるため、ナス型フラスコ内を約１０分間真空脱気処理した。
【００７８】
次に、ナス型フラスコ内の活性炭素繊維を水と共に蓋付き円筒型瓶に移し、これに０．００６モルのＬａ（ＮＯ3）3・６Ｈ2Ｏ、０．０００３モルのＩｒＣｌ4および０．０５７モルの尿素を加えて溶解し、５００ｍｌの水溶液を得た。そして、この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。以下、触媒成分１の場合と同様に操作したところ、イリジウム元素と酸化ランタンとを担持した活性炭素繊維（触媒成分３）が得られた。
【００７９】
比較例２
下記のようにして得られた触媒成分１と触媒成分２とを１：１の割合で均一に混合し、混合触媒を得た。得られた混合触媒の組成および物理的性状は表１に示す通りである。
【００８０】
（触媒成分１）
蓋付き円筒型瓶に０．６モルのＦｅ（ＮＯ3）3・９Ｈ2Ｏ、０．０３モルのＨＡｕＣｌ4、３．６モルの尿素および水を加えて溶解し、５００ｍｌの水溶液を得た。この際、水溶液に対して約１０分間真空脱気処理した。この水溶液を８０℃のウオーターバス中で攪拌しながら５時間加熱処理した。この際、水溶液中の尿素が加水分解してＯＨ-イオンが生成し、水溶液のｐＨがアルカリ性側に徐々に移行した。この結果、水溶液中には、水酸化鉄（Ｆｅ（ＯＨ）3）と水酸化金（Ａｕ（ＯＨ）3）とが析出して沈殿した。
【００８１】
沈殿を水溶液から濾過して取り出し、これをアスピレーターで吸引しながら十分に水洗した後に約１０時間真空乾燥した。この沈殿をガス流通式石英管に充填し、この石英管に空気を沈殿約１ｇに対して２５０ｍｌ／分の流速で流しながら沈殿を３００℃で３時間焼成した。これにより、金元素を担持した三酸化二鉄からなる触媒（触媒成分１）が得られた。
【００８２】
（触媒成分２）
蓋付き円筒型瓶に０．６モルのＳｎＣｌ4、０．０３モルのＰｔＣｌ4、３．６モルの尿素および水を加えて溶解し、５００ｍｌの水溶液を得た。以下、触媒成分１の場合と同様に操作したところ、白金元素を担持した二酸化スズからなる触媒（触媒成分２）が得られた。
【００８３】
【表１】
評価
各実施例および各比較例で得られた触媒について、一酸化炭素１，０００ｐｐｍ、ｏ−クロロフェノール１，４００ｐｐｍ、アセトアルデヒド７００ｐｐｍ、ヒドラジン７５０ｐｐｍ、メチルアミン４５０ｐｐｍ、メチルメルカプタン２００ｐｐｍ、水３．９容量％および酸素１８．６５容量％を含む窒素混合ガスに対する分解活性と活性安定性とを調べた。なお、実施例３および比較例２で得られた触媒は、平均粒径が０．５ｍｍの石英砂と１：４（触媒：石英砂）の割合で混合したものを試料とした。
【００８５】
（分解活性試験）
触媒の分解活性は、固定床流通式反応装置を用いて評価した。ここでは、内径が１９ｍｍのステンレス製の反応管に触媒試料２．０ｇ（１４ｍｌ）を充填し、反応管の両端を適量のガラスウールで封止した。そして、この反応管に、２０，０００ｈｒ-1、温度１３０℃の条件で上述の窒素混合ガスを通過させた。
【００８６】
反応管を通過する前後の窒素混合ガスをガスクロマトグラフィー（株式会社柳本製作所の商品名“Ｈ１８８０Ｔ型”）を用いて分析した。この際、ｏ−クロロフェノール、アセトアルデヒド、ヒドラジン、メチルアミンおよびメチルメルカプタンの検出用としてＦＩＤ検出器を用い、一酸化炭素の検出用としてＴＣＤ検出器を用いた。
【００８７】
触媒の分解活性は、窒素混合ガス中に含まれる各成分の分解率を求めることにより評価した。ここで、分解率は、反応管に窒素混合ガスを流し始めてから２時間経過時点での反応管の入口側で測定したガスクロマトグラフィーにおける各成分のピーク面積と、同時点での反応管の出口側で測定したガスクロマトグラフィーにおける各成分のピーク面積とに基づいて算出した。結果を表２に示す。
【００８８】
（活性安定性）
上述の触媒活性試験を２４時間継続し、分解率の変化を調べた。結果を図４〜図８に示す。なお、図４は実施例１の触媒、図５は実施例２の触媒、図６は実施例３の触媒、図７は比較例１の触媒および図８は比較例２の触媒の結果をそれぞれ示している。
【００８９】
【表２】
【発明の効果】
本発明の集積化触媒は、複数種類の触媒単位がナノメートルレベルで集合したものであるため、複数種類の触媒を単に混合しただけのものとは異なり、種類の異なる複数の物質に対する活性を同時に効果的に発揮し得る。
【００９１】
また、本発明に係る触媒の製造方法によれば、種類の異なる複数の物質に対する活性を同時に効果的に発揮し得る、金属元素と金属酸化物とが組合わされた触媒単位の複数種類がナノメートルレベルで集合した集積触媒を実現することができる。
【図面の簡単な説明】
【図１】本発明の集積化触媒の一形態の概念図。
【図２】本発明の集積化触媒の他の形態の概念図。
【図３】三酸化二鉄および二酸化スズの水溶液中におけるイオン吸着密度とｐＨとの関係を示すグラフ。
【図４】実施例１に係る触媒の活性安定性を示すグラフ。
【図５】実施例２に係る触媒の活性安定性を示すグラフ。
【図６】実施例３に係る触媒の活性安定性を示すグラフ。
【図７】比較例１に係る触媒の活性安定性を示すグラフ。
【図８】比較例２に係る触媒の活性安定性を示すグラフ。
【符号の説明】
１，２ 集積化触媒
ａ，ｂ，ｃ 触媒単位
Ｕ 触媒単位群
Ｓ 担体[0001]
[Industrial application fields]
The present invention relates to a catalyst, particularly an integrated catalyst.
[0002]
[Prior art and its problems]
Exhaust gases emitted from waste incineration facilities and automobiles contain a wide variety of hazardous substances including carbon monoxide, aldehydes, sulfides, hydrocarbons, nitrogen compounds and organochlorine compounds. Yes. For this reason, in waste incineration facilities and the like, an attempt is made to treat exhaust gas using a catalyst and reduce the concentration of harmful substances contained therein.
[0003]
By the way, the catalyst usually shows a specific decomposition activity only for a specific kind of harmful substance, and does not show a universal decomposition activity for all kinds of harmful substances. Also, certain of the harmful substances can even deactivate certain catalysts. For example, a catalyst in which platinum element is supported on soot dioxide exhibits high oxidative decomposition activity against hydrocarbons in a high temperature region, but is easily poisoned and inactivated by carbon monoxide in a low temperature region. For this reason, when it is necessary to effectively treat exhaust gas containing many kinds of harmful substances, a method using a combination of many kinds of catalysts according to the kind of harmful substances, for example, using many kinds of existing catalysts. A method of uniformly mixing and using can be considered.
[0004]
However, when many kinds of catalysts are mixed, even if the catalysts are uniformly mixed, different kinds of catalysts are located far apart at the μm level. Since the decomposition of harmful substances by the catalyst is due to the reaction at the molecular level on the catalyst, many kinds of harmful substances can be effectively treated simultaneously at the molecular level unless different types of catalysts are in close proximity. It is difficult to disassemble.
[0005]
An object of the present invention is to realize a catalyst that can simultaneously and effectively exhibit a plurality of different types of substances.
[0009]
[Means for Solving the Problems]
The integrated catalyst of the present invention isThe first catalyst unit in which gold element is supported on ferric trioxide, the second catalyst unit in which platinum element is supported on tin dioxide, and the third catalyst unit in which iridium element is supported on lanthanum oxide are included. A catalyst unit group is formed, and the first catalyst component, the second catalyst component, and the third catalyst component are aggregated at the nanometer level to form a catalyst unit group.This integrated catalystThen, for example, the catalyst unit group is arranged on one kind of support selected from activated carbon and activated carbon fiber.
[0010]
The method for producing an integrated catalyst according to the present invention is a method for producing an integrated catalyst in which a plurality of types of catalyst units in which a specific metal element is combined with a metal oxide are assembled at a nanometer level. A first step of preparing a metal oxide group including a plurality of types of metal oxides integrated at a nanometer level, and a metal element corresponding to each of the metal oxides included in the metal oxide group And a second step of selectively supporting.
[0011]
here,The second process consists of multiple typesUtilizing the difference in isoelectric point of the metal oxide, selectively attaching ions of the corresponding metal element to only one kind of metal oxide in the group of metal oxides, and the metal element And a step of converting these ions into a metal element, and a multi-step process including these steps is repeated for each type of metal oxide included in the metal oxide group.
[0012]
In such a second step, the step of converting the metal element ion into the metal element includes, for example, a step of inducing the metal element ion into the metal element hydroxide, and converting the hydroxide into the metal element. And a process of performing.
[0013]
The above-described method for producing an integrated catalyst according to the present invention includes, for example, a metal oxide precursor that can be converted into a metal oxide, and a metal element precursor that can be converted into a metal element corresponding to the metal oxide. And a third step including a step of simultaneously depositing the metal oxide precursor and the metal element precursor into a metal oxide and a metal element, respectively.
[0014]
In this case, the third step may be repeated a plurality of times. Moreover, you may implement a 3rd process at least once while repeating the multistep process in the above-mentioned 2nd process.
[0015]
Other integrated catalysts according to the present inventionThe manufacturing method isCatalyst unit group including a number of first catalyst units supported on ferric trioxide, a second catalyst unit in which platinum element is supported on tin dioxide, and a third catalyst unit in which iridium element is supported on lanthanum oxide. And a first catalyst component, a second catalyst component, and a third catalyst component are aggregated at a nanometer level to produce an integrated catalyst. This manufacturing method includes the following steps.
[0016]
A process for preparing an aqueous solution containing ferric trioxide and tin dioxide accumulated at the nanometer level.
◎ Platinum cation from the platinum compound by dissolving the platinum compound in the aqueous solution and setting the pH of the aqueous solution to be more alkaline than the isoelectric point of tin dioxide and more acidic than the isoelectric point of ferric trioxide Is selectively adhered only to tin dioxide, and the pH of the aqueous solution is further adjusted to the alkaline side within the range not exceeding the isoelectric point of ferric trioxide to derive platinum hydroxide from the platinum cation.
◎ Process to convert platinum hydroxide into platinum by heat treatment.
◎ Dissolve the gold compound in the aqueous solution and set the pH of the aqueous solution between the isoelectric point of tin dioxide and the isoelectric point of ferric trioxide so that the gold anion from the gold compound is changed to only ferric trioxide. A step of selectively adhering and adjusting the pH of the aqueous solution to the alkaline side to induce gold hydroxide from the gold anion.
◎ Process to convert gold hydroxide to heat by heat treatment.
A step of dissolving lanthanum salt and iridium salt in an aqueous solution and then adjusting the pH of the aqueous solution to produce lanthanum hydroxide and iridium hydroxide in the aqueous solution.
A process of heat-treating lanthanum hydroxide and iridium hydroxide to convert them into lanthanum oxide and iridium elements, respectively.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The integrated catalyst of the present invention includes a large number of catalyst units. In the present invention, the catalyst unit refers to a unit that can exhibit its own catalytic function. For example, metal elements, metal oxides, and combinations of metal elements and metal oxides (hereinafter sometimes referred to as “composite catalysts”) are catalyst units in the present invention.
[0018]
Here, the metal element is a known element that is known to exhibit a catalytic function capable of decomposing at least one component among various harmful substances contained in various exhaust gases, for example. Examples include gold, platinum, iridium, ruthenium, rhodium, palladium and silver.
[0019]
In addition, the metal oxide is a known one that is known to be able to exhibit the same catalytic function as the metal element as a carrier or promoter of the above-described metal element. Fe2OThree), Tin dioxide (SnO)2) And lanthanum oxide (La2OThree). In addition, examples of the metal oxide include oxides of metal elements such as aluminum, silicon, magnesium, titanium, vanadium, manganese, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, tungsten, cerium, and praseodymium. be able to.
[0020]
Further, a combination of a metal element and a metal oxide, that is, a composite catalyst is, for example, a combination of one of the above metal elements and one of the above metal oxides. More specifically, examples include those in which a gold element is supported on ferric trioxide, those in which platinum is supported on tin dioxide, and those in which iridium is supported on lanthanum oxide.
[0021]
The catalyst unit of the composite catalyst is a combination of the metal element and the metal oxide so that the metal element and the metal oxide constituting the catalyst unit share the functions and have a synergistic effect that can enhance the required catalyst functions with each other. It is preferable. For example, the catalytic unit in which platinum element is supported on tin dioxide that can easily take in gas phase oxygen in oxidative decomposition of hydrocarbons is oxidative decomposition on hydrocarbons that can be achieved with tin dioxide alone or platinum element alone. Compared to activity, when both are combined, the oxidative degradation activity increases synergistically. NOxA catalytic unit in which iridium element having an activity to decompose amines is supported on lanthanum oxide having affinity for lanthanum oxide can exhibit decomposition activity to amines in the same manner with lanthanum oxide alone or iridium element alone, but both are combined. And the decomposition activity increases synergistically.
[0022]
The integrated catalyst of the present invention includes a plurality of types of catalyst units as described above. The combination of the types of catalyst units is not particularly limited. For example, a combination of a plurality of types of metal elements, a combination of a plurality of types of metal oxides, a combination of a plurality of types of composite catalysts, and a metal element, A combination of two or more of metal oxides and composite catalysts. In the present invention, since the required catalytic function can be most effectively exhibited, each of the plurality of types of catalyst units is a composite catalyst, that is, a combination of a metal oxide and a metal element. Those consisting of are preferred.
[0023]
The combination of catalyst units from the functional viewpoint of the catalyst can be appropriately set according to the use of the integrated catalyst of the present invention, in other words, the catalyst function required for the integrated catalyst of the present invention, and is particularly limited. Usually, each catalyst unit has a unique catalyst function different from other catalyst units, and at least one catalyst unit is a catalyst function of at least one of the other catalyst units. Is preferably set so as to be able to complement. Incidentally, the term “complementation of catalyst function” as used herein means that one catalyst unit maintains or promotes the catalytic activity of another catalyst unit.
[0024]
For example, a catalyst unit in which platinum element is supported on tin dioxide, which exhibits oxidative decomposition activity against hydrocarbons, and NOxIn the case of using at least one kind of catalyst unit in which iridium element showing decomposition activity for amines is supported on lanthanum oxide having affinity with these, these catalyst units are formed when hydrocarbons or amines are decomposed Since it is easily poisoned by carbon monoxide and loses its catalytic activity, it supports the catalytic activity of those catalytic units, and supports gold element on ferric trioxide, which shows decomposition activity against carbon monoxide. The combined catalyst units are preferably combined.
[0025]
The integrated catalyst of the present invention is composed of a catalyst unit group including a large number of a plurality of types of catalyst units as described above. Here, the catalyst unit group is not simply a mixture of a plurality of types of catalyst units, but a level of nanometers or less where the number of the plurality of types of catalyst units is several times the size of atoms or molecules. Are assembled and integrated. FIG. 1 shows a conceptual diagram of an embodiment of such an integrated catalyst of the present invention. In the figure, the
[0026]
The
[0027]
What is preferable as the integrated catalyst of the present invention is a composite catalyst in which each of a plurality of types of catalyst units is a combination of a metal oxide and a metal element, and at least one of these catalyst units is It is selected so as to be able to complement at least one of the catalyst functions of other catalyst units. In this case, it is particularly preferable that at least one of the catalyst units is set to a combination in which the metal oxide and the metal element can synergistically enhance the catalyst function as described above.
[0028]
As an example of such an integrated catalyst, a first catalyst unit in which gold element is supported on ferric trioxide, a second catalyst unit in which platinum element is supported on tin dioxide and an iridium element are supported on lanthanum oxide. The catalyst unit includes a large number of the three types of catalyst units of the third catalyst unit, and these catalyst units are aggregated at the nanometer level to form a catalyst unit group. In addition, this catalyst unit group may be arrange | positioned on the support | carrier consisting of activated carbon or activated carbon fiber.
[0029]
In such an integrated catalyst, the first catalyst component exhibits excellent low-temperature oxidative decomposition activity for carbon monoxide and aldehydes. In particular, carbon monoxide exhibits excellent oxidative degradation activity even at −70 ° C. In addition, the second catalyst component exhibits excellent oxidative decomposition activity for hydrocarbons and the like in a high temperature region. Furthermore, the third catalyst component exhibits excellent decomposition activity for amines. For this reason, when this integrated catalyst is used as a catalyst for treating exhaust gas containing organic chlorine compounds such as carbon monoxide, aldehydes, hydrocarbons, amines, mercaptans and dioxin, The concentration of these harmful substances contained can be effectively reduced simultaneously at a relatively low temperature, and the function can be maintained for a long time.
[0030]
In particular, in this integrated catalyst, the first catalyst unit can exhibit a complementary function of the second catalyst unit and the third catalyst unit. That is, the second catalyst unit and the third catalyst unit are poisoned by carbon monoxide generated by themselves when carbons and amines are decomposed and carbon monoxide contained in exhaust gas, respectively, and the activity is remarkably high. Although the carbon monoxide can be decomposed by the first catalyst unit, the activity of the second catalyst unit and the third catalyst unit can be maintained.
[0031]
In other words, this integrated catalyst is different from the one in which the first catalyst unit, the second catalyst unit, and the third catalyst unit are simply mixed uniformly, and these catalyst units are aggregated and integrated at the nanometer level. (That is, the catalyst units are assembled close to each other at the nanometer level), and the carbon monoxide generated by the molecular level reaction in the second catalyst unit and the third catalyst unit is nano-ranged in these catalyst units. It can be rapidly decomposed by the first catalyst component located close to the meter level.
[0032]
As a result, this integrated catalyst can exhibit the required catalytic function effectively and continuously for a long period of time.
Since such an integrated catalyst of the present invention can exhibit the above-described functions, for example, a catalyst for treating exhaust gas discharged from a waste incineration facility or various industrial plants, a catalyst for an air cleaner, and a fuel It can be used as a battery catalyst.
[0033]
The integrated catalyst of the present invention can be produced by, for example, simultaneously depositing various metal elements and metal oxides in an aqueous solution by a known method such as a coprecipitation method. However, among integrated catalysts, a specific metal element and a specific metal oxide are paired when a large number of catalyst units in which a metal element and a metal oxide are combined are assembled at a nanometer level. Therefore, it is difficult to manufacture by the usual coprecipitation method. Therefore, a method for producing such an integrated catalyst will be described below.
[0034]
Here, as an example, an integrated catalyst comprising a catalyst unit group including a large number of catalyst units in which gold element is supported on ferric trioxide and a large number of catalyst units in which platinum element is supported on tin dioxide, and a manufacturing method thereof. Will be described for each process.
[0035]
First step
In this step, a metal oxide group in which a plurality of types of metal oxides, that is, ferric trioxide and tin dioxide are integrated at a nanometer level is adjusted. Here, first, an aqueous solution containing an iron salt and a tin salt (for example, both nitrates) is prepared, and iron hydroxide and tin hydroxide are prepared by gradually adjusting the pH of the aqueous solution to the alkaline side. Here, as a method for adjusting the pH of the aqueous solution to the alkaline side, for example, (1) a method of dissolving urea in an aqueous solution in advance and heating the aqueous solution to about 70 ° C., and (2) an aqueous solution For example, a method of gradually dropping a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution can be employed.
[0036]
In the case of method (1), when the aqueous solution is heated, urea slowly decomposes and NHFour +Ion and OH-And ions are generated. As a result, the pH of the aqueous solution gradually changes to the alkaline side, and when the pH value becomes more alkaline than a certain value, iron hydroxide and tin hydroxide that are insoluble in water precipitate in the aqueous solution while collecting at the nanometer level. And precipitate in aqueous solution. When the metal hydroxide group thus obtained is heat-treated in an oxygen-containing atmosphere, the metal hydroxide group is converted into a target metal oxide group, that is, a metal oxide group containing ferric trioxide and tin dioxide. Is done.
[0037]
On the other hand, in the case of method (2), a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution is gradually dropped while stirring an aqueous solution containing a metal salt, that is, the iron salt and tin salt described above. As a result, the pH of the aqueous solution gradually changes to the alkaline side, and when the pH value becomes more alkaline than a certain value, iron hydroxide and tin hydroxide that are insoluble in water precipitate in the aqueous solution while collecting at the nanometer level. And precipitate in aqueous solution. When the metal hydroxide group thus obtained is heat-treated in an oxygen-containing atmosphere, the metal hydroxide group is converted into a target metal oxide group, that is, a metal oxide group containing ferric trioxide and tin dioxide. The
[0038]
In this step, as described above, a plurality of metal salts may be simultaneously added to the aqueous solution, and a plurality of metal oxides corresponding to them may be simultaneously generated, or one metal salt may be added at a time. Then, the corresponding metal oxides may be sequentially generated one by one.
[0039]
Further, in the case of producing an integrated catalyst in which the catalyst unit group is arranged on the support, the above-described support is previously arranged in the aqueous solution in this step. In this way, the metal hydroxide group described above is precipitated on the support, so that the metal oxide group can be generated (supported) on the support.
[0040]
Second step
In this step, for each metal oxide included in the metal oxide group obtained in the first step, that is, ferric trioxide and tin dioxide, corresponding metal elements, that is, gold element and platinum element, respectively. Is selectively supported.
[0041]
Here, using the difference in isoelectric point between ferric trioxide and tin dioxide, the corresponding metal element is selectively supported. FIG. 3 shows the relationship between ion adsorption density and pH in an aqueous solution of ferric trioxide and tin dioxide. As shown in the figure, the isoelectric point (pH) of tin dioxide is 4.5, and the isoelectric point of ferric trioxide is 8.0. For this reason, when the pH of the aqueous solution is less than 4.5, both the surfaces of tin dioxide and ferric trioxide are positively charged. In addition, when the pH of the aqueous solution is in the range of 4.5 to 8.0, the surface of tin dioxide is negatively charged and the surface of ferric trioxide is positively charged.
[0042]
In this step, the metal element corresponding to these metal oxides can be selectively supported using the difference in isoelectric point between ferric trioxide and tin dioxide as described above. Specifically, first, a platinum compound (for example, platinum salt, more specifically, for example, platinum chloride) is added to an aqueous solution containing ferric trioxide and tin dioxide, and the pH of the aqueous solution is 4.5 or more. And it sets to the acid side rather than the isoelectric point of ferric trioxide. As a result, cationic platinum ions (Pt4+) Is attracted to the surface of tin dioxide having a negatively charged surface at that pH and repels the positively charged ferric trioxide.
[0043]
In this state, when the pH of the aqueous solution is further set to the alkaline side, platinum ions are converted into platinum hydroxide (Pt (OH)).Four・ 2H2O), and is selectively deposited only on tin dioxide. Thereafter, when the metal oxide group is taken out from the aqueous solution and subjected to heat treatment, platinum hydroxide is converted into platinum element, and a metal oxide group containing tin dioxide supporting the platinum element and ferric trioxide is obtained.
[0044]
Next, an aqueous solution of this metal oxide group is prepared again, and a gold compound (for example, an acid containing a gold element, more specifically, for example, chloroauric acid) is added thereto. When the pH of the aqueous solution is 4.5 or more and set to the acidic side of the isoelectric point of ferric trioxide, anionic gold ions (for example, AuCl) generated in the aqueous solution are set.Four -) Is attracted to ferric trioxide whose surface has a positive charge in the pH region, and repels tin dioxide whose surface has a negative charge. In this state, when the pH of the aqueous solution is further set to the alkaline side, gold ions are converted into gold hydroxide (Au (OH)ThreeAnd selectively deposits only on ferric trioxide. Thereafter, when the metal oxide group is taken out from the aqueous solution and heat-treated, the gold hydroxide is converted into a gold element. As a result, a catalyst unit group including a large number of catalyst units made of tin dioxide carrying platinum elements and catalyst units made of ferric trioxide carrying gold elements, that is, a target integrated catalyst is obtained. In the first step described above, when the metal oxide group is generated on the support, this integrated catalyst is formed on the support.
[0045]
Third step
In addition to the catalyst unit consisting of tin dioxide supporting platinum element and the catalyst unit consisting of ferric trioxide supporting gold element, for example, the catalyst unit group further includes a catalyst unit consisting of lanthanum oxide supporting iridium element In the case of producing an integrated catalyst, a third step described below is further applied to the integrated catalyst obtained through the first step and the second step as described above.
[0046]
In this step, first, a metal oxide precursor that can be converted into lanthanum oxide and a metal element precursor that can be converted into iridium element are simultaneously deposited on the integrated catalyst obtained in the second step. The metal oxide precursor and metal element precursor referred to here are, for example, lanthanum hydroxide and iridium hydroxide, respectively.
[0047]
Here, usually, a metal salt for forming a metal oxide precursor (in this case, a lanthanum salt, more specifically, lanthanum nitrate, for example) and a metal salt for forming a metal element precursor (In the case of this example, an aqueous solution containing an iridium salt, more specifically iridium chloride, for example) is prepared, and the integrated catalyst obtained in the second step is added thereto. Then, the pH of the aqueous solution is gradually adjusted to the alkaline side, and lanthanum hydroxide (metal oxide precursor) and iridium hydroxide (metal element precursor) are precipitated simultaneously. At this time, lanthanum hydroxide and iridium hydroxide are precipitated while being assembled with each other at the nanometer level, and are simultaneously accumulated at the nanometer level with respect to the integrated catalyst obtained in the second step.
[0048]
In addition, as a method for adjusting the pH of the aqueous solution, a method similar to the method that can be adopted in the first step described above, that is, a method in which urea is added to the aqueous solution and heated to about 70 ° C. and the aqueous solution On the other hand, a method of gradually dropping a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution can be employed.
[0049]
Next, the integrated catalyst in which lanthanum hydroxide and iridium hydroxide are additionally accumulated is taken out from the aqueous solution and heat-treated in the air. Thereby, lanthanum hydroxide and iridium hydroxide are simultaneously converted into lanthanum oxide and iridium element, respectively, and a new catalyst unit composed of lanthanum oxide supporting the iridium element is generated. Thus, a catalyst unit comprising three types of catalyst units: a catalyst unit composed of tin dioxide supporting platinum element, a catalyst unit composed of ferric trioxide supporting gold element, and a catalyst unit composed of lanthanum oxide supporting iridium element. An integrated catalyst consisting of a group is obtained.
[0050]
In the heat treatment step in the final stage as described above, iridium hydroxide may be converted to iridium oxide depending on the conditions at that time. In this case, if it is appropriately heat-treated in a reducing atmosphere, iridium element Can be converted to
[0051]
The above-described manufacturing method according to the present invention is an integrated catalyst other than the integrated catalyst according to the above-described example, that is, another integrated type composed of a plurality of types of catalyst units in which a metal element is supported on a metal oxide. The present invention can also be applied to the production of a catalyst. In this case, a metal oxide group containing three or more types of metal oxides may be formed in the first step described above, and the second step may be repeated three or more times depending on the type of catalyst unit. Moreover, according to the kind of catalyst unit, you may repeat the above-mentioned 3rd process twice or more. Furthermore, in the above-described manufacturing method, it is not always necessary to perform the third step after completing the first step and the second step. The first and second steps are performed after the third step is performed. The step may be performed, or the third step may be performed once or twice as appropriate while the second step is repeatedly applied to the metal oxides included in the metal oxide group obtained in the first step. You may insert more than once.
[0052]
【Example】
Example 1
500 ml of water was added to the eggplant-shaped flask, and 10 g of coal tar pitch activated carbon fiber (average fiber diameter = 14.0 μm, BET specific surface area = 1,920 m).2/ G, average pore diameter = 19.01 angstroms). At this time, in order to allow water to enter the pores of the activated carbon fiber, the eggplant-shaped flask was vacuum degassed for about 10 minutes.
[0053]
Next, the activated carbon fiber in the eggplant-shaped flask was transferred to a cylindrical bottle with a lid together with water, and 0.006 mol Fe (NO) was added thereto.Three)Three・ 9H2O, 0.006 mol SnClFourAnd 0.036 mol of urea was added and dissolved to obtain 500 ml of an aqueous solution. And this aqueous solution was heat-processed for 5 hours, stirring in a 80 degreeC water bath. At this time, urea in the aqueous solution is hydrolyzed to generate OH.-Ions were generated, and the pH of the aqueous solution gradually shifted to the alkaline side. As a result, the activated carbon fiber in the aqueous solution contains iron hydroxide (Fe (OH)Three) And tin hydroxide (Sn (OH)Four) Precipitated and precipitated.
[0054]
The activated carbon fiber was taken out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. This activated carbon fiber is filled in a gas flow type quartz tube, and a mixed gas containing 2% by volume of oxygen and 98% by volume of nitrogen is supplied to the quartz tube at a flow rate of 250 ml / min with respect to about 1 g of activated carbon fiber. The activated carbon fiber was fired at 300 ° C. for 3 hours. As a result, iron hydroxide and tin hydroxide were converted into oxides, and activated carbon fibers carrying ferric trioxide and tin dioxide were obtained.
[0055]
Next, 10 g of activated carbon fibers carrying ferric trioxide and tin dioxide were immersed in 500 ml of water in an eggplant-shaped flask and degassed in the same manner as described above. Thereafter, the activated carbon fiber is transferred together with water into a cylindrical bottle with a lid, to which 0.0003 mol of PtCl is added.FourWas added to prepare a 500 ml aqueous solution. The pH of this aqueous solution was 1.8.
[0056]
While stirring until the pH of the aqueous solution reached 6.0, 5% aqueous sodium carbonate solution was gently added dropwise, and the aqueous solution was aged for 2 hours while maintaining this pH. In this process, when the pH of the aqueous solution is equal to or higher than the isoelectric point of tin dioxide, that is, 4.5 or higher, platinum ions (Pt4+) Selectively migrates only to the negatively charged tin dioxide surface, and when the pH reaches 6.0, platinum ions are converted into platinum hydroxide (Pt (OH)Four・ 2H2It changed to O) and precipitated and precipitated only on the surface of tin dioxide.
[0057]
The activated carbon fiber treated as described above was taken out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. This activated carbon fiber is filled in a gas flow type quartz tube, and a mixed gas containing 2% by volume of oxygen and 98% by volume of nitrogen is supplied to the quartz tube at a flow rate of 250 ml / min with respect to about 1 g of activated carbon fiber. The activated carbon fiber was fired at 300 ° C. for 3 hours. Subsequently, the activated carbon fiber was reduced at 200 ° C. for 3 hours while flowing hydrogen gas into the quartz tube at a flow rate of 100 ml / min with respect to about 1 g of activated carbon fiber. As a result, an activated carbon fiber carrying a catalyst unit made of tin dioxide carrying platinum element and ferric trioxide was obtained.
[0058]
Next, 10 g of activated carbon fiber carrying a catalyst unit made of tin dioxide carrying platinum element and ferric trioxide was immersed in 500 ml of water in an eggplant type flask, and degassed in the same manner as described above. Thereafter, the activated carbon fiber was transferred to a cylindrical bottle with a lid together with water, and 0.0003 mol of HAuCl was added thereto.Four・ 4H2O was added to prepare a 500 ml aqueous solution. The pH of this aqueous solution was 2.8.
[0059]
While stirring until the pH of the aqueous solution reached 7.0, 5% aqueous sodium carbonate solution was slowly added dropwise, and the aqueous solution was aged for 5 hours while maintaining this pH. In this process, when the pH of the aqueous solution is higher than the isoelectric point of tin dioxide, that is, 4.5 or higher, gold ions (AuCl in the aqueous solution)Four-) Selectively migrates only to the surface of the positively charged ferric trioxide, and when the pH reaches 7.0, the gold ion becomes gold hydroxide (Au (OH)Three) And precipitated and precipitated only on the surface of ferric trioxide.
[0060]
The activated carbon fiber treated as described above was taken out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. This activated carbon fiber is filled in a gas flow type quartz tube, and a mixed gas containing 2% by volume of oxygen and 98% by volume of nitrogen is supplied to the quartz tube at a flow rate of 250 ml / min with respect to about 1 g of activated carbon fiber. The activated carbon fiber was fired at 300 ° C. for 3 hours. As a result, an activated carbon fiber supporting two catalyst units, that is, a catalyst unit composed of tin dioxide supporting platinum element and a catalyst unit composed of ferric trioxide supporting gold element, that is, an integrated catalyst was obtained. The composition and physical properties of the obtained integrated catalyst are as shown in Table 1.
[0061]
Example 2
After 10 g of the integrated catalyst obtained in Example 1 was immersed in 500 ml of water in an eggplant-shaped flask and degassed in the same manner as in Example 1, the integrated catalyst was placed in a cylindrical bottle with a lid together with water. Moved. To this, 0.006 mol of La (NOThree)Three・ 6H2O, 0.0003 mol IrClThreeAnd 0.019 moles of urea were added to prepare a 500 ml aqueous solution. And this aqueous solution was heat-processed for 5 hours, stirring in a 80 degreeC water bath. At this time, urea in the aqueous solution is hydrolyzed to generate OH.-Ions were generated, and the pH of the aqueous solution gradually shifted to the alkaline side. As a result, the activated carbon fiber constituting the integrated catalyst in the aqueous solution contains iridium hydroxide (Ir (OH)).Three) And lanthanum hydroxide (La (OH)Three) Precipitated and precipitated.
[0062]
The integrated catalyst treated as described above was taken out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. The integrated catalyst was filled in a gas flow type quartz tube, and the integrated catalyst was calcined at 300 ° C. for 3 hours while flowing air at a flow rate of 250 ml / min with respect to about 1 g of the integrated catalyst. Subsequently, the integrated catalyst was reduced at 200 ° C. for 3 hours while flowing hydrogen gas through the quartz tube at a flow rate of 100 ml / min with respect to about 1 g of the integrated catalyst. As a result, in addition to the catalyst unit consisting of tin dioxide supporting platinum element and the catalyst unit consisting of ferric trioxide supporting gold element, the catalyst unit consisting of lanthanum oxide supporting iridium element is accumulated on the activated carbon fiber. An integrated catalyst was obtained. The composition and physical properties of the obtained integrated catalyst are as shown in Table 1.
[0063]
Example 3
In a cylindrical bottle with a lid charged with 500 ml of water, 0.6 mol of Fe (NOThree)Three・ 9H2O, 0.6 mol SnClFourAnd 3.6 moles of urea were added and dissolved to obtain an aqueous solution. And this aqueous solution was heat-processed for 5 hours, stirring in a 80 degreeC water bath. At this time, urea in the aqueous solution is hydrolyzed to generate OH.-Ions were generated, and the pH of the aqueous solution gradually shifted to the alkaline side. As a result, the activated carbon fiber in the aqueous solution contains iron hydroxide (Fe (OH)Three) And tin hydroxide (Sn (OH)Four) And precipitated.
[0064]
This aqueous solution was filtered to collect a precipitate, which was sufficiently washed with water while being sucked with an aspirator and then vacuum-dried for about 10 hours. Thereafter, the precipitate was filled into a gas flow-type quartz tube, and the precipitate was calcined at 300 ° C. for 3 hours while flowing air at a flow rate of 250 ml / min with respect to about 1 g of precipitate. As a result, a metal oxide group consisting of ferric trioxide and tin dioxide was obtained.
[0065]
Next, 10 g of the metal oxide group was immersed in 500 ml of water in the eggplant type flask, and degassed as described above. Thereafter, the metal oxide group together with water was transferred to a cylindrical bottle with a lid, and 0.03 mol of PtCl was added thereto.FourWas added to prepare a 500 ml aqueous solution. The pH of this aqueous solution was 1.8.
[0066]
While stirring until the pH of the aqueous solution reached 6.0, a 5% sodium carbonate aqueous solution was slowly added dropwise, and the aqueous solution was aged for 5 hours while maintaining this pH. In this process, when the pH of the aqueous solution is equal to or higher than the isoelectric point of tin dioxide, that is, 4.5 or higher, platinum ions (Pt4+) Selectively migrates only to the negatively charged tin dioxide surface, and when the pH reaches 6.0, platinum ions are converted into platinum hydroxide (Pt (OH)Four) And deposited and precipitated only on the surface of tin dioxide.
[0067]
The metal oxide group treated as described above was taken out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. The metal oxide group was filled into a gas flow type quartz tube, and the metal oxide group was fired at 300 ° C. for 3 hours while flowing air at a flow rate of 250 ml / min with respect to about 1 g of the metal oxide group. . Subsequently, the metal oxide group was reduced at 200 ° C. for 3 hours while flowing hydrogen gas through the quartz tube at a flow rate of 100 ml / min with respect to about 1 g of the metal oxide group. As a result, a composite of a catalyst unit made of tin dioxide carrying platinum element and ferric trioxide was obtained.
[0068]
Next, 10 g of the composite was immersed in 500 ml of water in an eggplant-shaped flask and degassed in the same manner as described above. The composite is then transferred with water to a cylindrical bottle with a lid, to which 0.03 mol of HAuCl is added.Four・ 4H2O was added to prepare a 500 ml aqueous solution. The pH of this aqueous solution was 2.8.
[0069]
While stirring until the pH of the aqueous solution reached 7.0, 5% aqueous sodium carbonate solution was slowly added dropwise, and the aqueous solution was aged for 5 hours while maintaining this pH. In this process, when the pH of the aqueous solution is higher than the isoelectric point of tin dioxide, that is, 4.5 or higher, gold ions (AuCl in the aqueous solution)Four-) Selectively migrates only to the surface of the positively charged ferric trioxide, and when the pH reaches 7.0, the gold ion becomes gold hydroxide (Au (OH)Three) And precipitated and precipitated only on the surface of ferric trioxide.
[0070]
The composite treated as described above was taken out from the aqueous solution, filtered, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. This composite was filled into a gas flow-type quartz tube, and the composite was fired at 300 ° C. for 3 hours while flowing air at a flow rate of 250 ml / min with respect to about 1 g of the composite. As a result, an integrated catalyst composed of two catalyst units, that is, a catalyst unit made of tin dioxide carrying platinum element and a catalyst unit made of ferric trioxide carrying gold element, was obtained. The composition and physical properties of the obtained integrated catalyst are as shown in Table 1.
[0071]
Comparative Example 1
[0072]
(Catalyst component 1)
500 ml of water was added to the eggplant-shaped flask, and 10 g of coal tar pitch activated carbon fiber (average fiber diameter = 14.0 μm, BET specific surface area = 1,920 m).2/ G, average pore diameter = 19.01 angstroms). At this time, in order to allow water to enter the pores of the activated carbon fiber, the eggplant-shaped flask was vacuum degassed for about 10 minutes.
[0073]
Next, the activated carbon fiber in the eggplant-shaped flask was transferred to a cylindrical bottle with a lid together with water, and 0.006 mol Fe (NO) was added thereto.Three)Three・ 9H2O, 0.0003 mol of HAuClFour・ 4H2O and 0.057 mol of urea were added and dissolved to obtain 500 ml of an aqueous solution. And this aqueous solution was heat-processed for 5 hours, stirring in a 80 degreeC water bath. At this time, urea in the aqueous solution is hydrolyzed to generate OH.-Ions were generated, and the pH of the aqueous solution gradually shifted to the alkaline side. As a result, the activated carbon fiber in the aqueous solution contains iron hydroxide (Fe (OH)Three) And gold hydroxide (Au (OH)Three) Precipitated and precipitated.
[0074]
The activated carbon fiber was taken out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. This activated carbon fiber is filled in a gas flow type quartz tube, and a mixed gas containing 2% by volume of oxygen and 98% by volume of nitrogen is supplied to the quartz tube at a flow rate of 250 ml / min with respect to about 1 g of activated carbon fiber. The activated carbon fiber was fired at 300 ° C. for 3 hours. As a result, an activated carbon fiber (catalyst component 1) carrying a gold element and ferric trioxide was obtained.
[0075]
(Catalyst component 2)
500 ml of water was added to the eggplant-shaped flask, and 10 g of coal tar pitch activated carbon fiber (average fiber diameter = 14.0 μm, BET specific surface area = 1,920 m).2/ G, average pore diameter = 19.01 angstroms). At this time, in order to allow water to enter the pores of the activated carbon fiber, the eggplant-shaped flask was vacuum degassed for about 10 minutes.
[0076]
Next, the activated carbon fiber in the eggplant type flask was transferred to a cylindrical bottle with a lid together with water, and 0.006 mol of SnCl was added thereto.Four0.0003 mol of PtClFourAnd 0.057 mol of urea was added and dissolved to obtain 500 ml of an aqueous solution. And this aqueous solution was heat-processed for 5 hours, stirring in a 80 degreeC water bath. Thereafter, when the same operation as in the case of the
[0077]
(Catalyst component 3)
500 ml of water was added to the eggplant-shaped flask, and 10 g of coal tar pitch activated carbon fiber (average fiber diameter = 14.0 μm, BET specific surface area = 1,920 m).2/ G, average pore diameter = 19.01 angstroms). At this time, in order to allow water to enter the pores of the activated carbon fiber, the eggplant-shaped flask was vacuum degassed for about 10 minutes.
[0078]
Next, the activated carbon fiber in the eggplant-shaped flask was transferred to a cylindrical bottle with a lid together with water, and 0.006 mol of La (NOThree)Three・ 6H2O, 0.0003 mol IrClFourAnd 0.057 mol of urea was added and dissolved to obtain 500 ml of an aqueous solution. And this aqueous solution was heat-processed for 5 hours, stirring in a 80 degreeC water bath. Thereafter, when the same operation as in the case of the
[0079]
Comparative Example 2
[0080]
(Catalyst component 1)
In a cylindrical bottle with a lid, 0.6 mol of Fe (NOThree)Three・ 9H2O, 0.03 mol HAuClFour3.6 mol of urea and water were added and dissolved to obtain 500 ml of an aqueous solution. At this time, the aqueous solution was vacuum deaerated for about 10 minutes. This aqueous solution was heat-treated for 5 hours with stirring in an 80 ° C. water bath. At this time, urea in the aqueous solution is hydrolyzed to generate OH.-Ions were generated, and the pH of the aqueous solution gradually shifted to the alkaline side. As a result, the aqueous solution contains iron hydroxide (Fe (OH)Three) And gold hydroxide (Au (OH)Three) And precipitated.
[0081]
The precipitate was filtered out from the aqueous solution, sufficiently washed with water while being sucked with an aspirator, and then vacuum-dried for about 10 hours. The precipitate was filled in a gas flow-type quartz tube, and the precipitate was calcined at 300 ° C. for 3 hours while flowing air at a flow rate of 250 ml / min with respect to about 1 g of the precipitate. Thereby, the catalyst (catalyst component 1) which consists of ferric trioxide which carried | supported the gold element was obtained.
[0082]
(Catalyst component 2)
0.6 mol of SnCl in a cylindrical bottle with a lidFour0.03 mol of PtClFour3.6 mol of urea and water were added and dissolved to obtain 500 ml of an aqueous solution. Thereafter, when the same operation as in the case of the
[0083]
[Table 1]
Evaluation
About the catalyst obtained in each Example and each comparative example, carbon monoxide 1,000 ppm, o-chlorophenol 1,400 ppm, acetaldehyde 700 ppm, hydrazine 750 ppm, methylamine 450 ppm, methyl mercaptan 200 ppm, water 3.9 vol% and The decomposition activity and activity stability with respect to a nitrogen mixed gas containing 18.65% by volume of oxygen were examined. In addition, the catalyst obtained in Example 3 and Comparative Example 2 was used as a sample mixed with quartz sand having an average particle diameter of 0.5 mm and a ratio of 1: 4 (catalyst: quartz sand).
[0085]
(Degradation activity test)
The decomposition activity of the catalyst was evaluated using a fixed bed flow type reactor. Here, a stainless steel reaction tube having an inner diameter of 19 mm was filled with 2.0 g (14 ml) of a catalyst sample, and both ends of the reaction tube were sealed with an appropriate amount of glass wool. And in this reaction tube, 20,000 hr-1The nitrogen mixed gas described above was passed under the condition of a temperature of 130 ° C.
[0086]
The nitrogen mixed gas before and after passing through the reaction tube was analyzed using gas chromatography (trade name “H1880T type” manufactured by Yanagimoto Seisakusho Co., Ltd.). At this time, an FID detector was used for detecting o-chlorophenol, acetaldehyde, hydrazine, methylamine and methyl mercaptan, and a TCD detector was used for detecting carbon monoxide.
[0087]
The decomposition activity of the catalyst was evaluated by determining the decomposition rate of each component contained in the nitrogen mixed gas. Here, the decomposition rate refers to the peak area of each component in the gas chromatography measured at the inlet side of the reaction tube after 2 hours from the start of flowing the nitrogen mixed gas into the reaction tube, and the outlet of the reaction tube at the same point. It calculated based on the peak area of each component in the gas chromatography measured on the side. The results are shown in Table 2.
[0088]
(Activity stability)
The above catalytic activity test was continued for 24 hours, and the change in the decomposition rate was examined. The results are shown in FIGS. 4 shows the results of the catalyst of Example 1, FIG. 5 shows the results of the catalyst of Example 2, FIG. 6 shows the results of the catalyst of Example 3, FIG. 7 shows the results of the catalyst of Comparative Example 1, and FIG. Show.
[0089]
[Table 2]
【The invention's effect】
Since the integrated catalyst of the present invention is a collection of a plurality of types of catalyst units at the nanometer level, it is different from a simple mixture of a plurality of types of catalysts, and at the same time, the activity against a plurality of different types of substances. It can be demonstrated effectively.
[0091]
In addition, according to the method for producing a catalyst according to the present invention, a plurality of types of catalyst units in which a metal element and a metal oxide are combined, which can effectively exhibit activity against a plurality of different types of substances simultaneously, are nanometers. Accumulated catalyst gathered at the level can be realized.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an embodiment of an integrated catalyst of the present invention.
FIG. 2 is a conceptual diagram of another embodiment of the integrated catalyst of the present invention.
FIG. 3 is a graph showing the relationship between ion adsorption density and pH in an aqueous solution of ferric trioxide and tin dioxide.
4 is a graph showing the activity stability of the catalyst according to Example 1. FIG.
5 is a graph showing the activity stability of the catalyst according to Example 2. FIG.
6 is a graph showing the activity stability of the catalyst according to Example 3. FIG.
7 is a graph showing the activity stability of a catalyst according to Comparative Example 1. FIG.
8 is a graph showing the activity stability of a catalyst according to Comparative Example 2. FIG.
[Explanation of symbols]
1, 2 Integrated catalyst
a, b, c catalyst unit
U catalyst unit group
S carrier
Claims (8)
前記第１触媒成分、前記第２触媒成分および前記第３触媒成分はナノメートルレベルで集合して前記触媒単位群を形成している、
集積化触媒。The first catalyst unit in which gold element is supported on ferric trioxide, the second catalyst unit in which platinum element is supported on tin dioxide, and the third catalyst unit in which iridium element is supported on lanthanum oxide are included. Consisting of a group of catalyst units,
The first catalyst component, the second catalyst component, and the third catalyst component are aggregated at a nanometer level to form the catalyst unit group.
Integrated catalyst.
ナノメートルレベルで集積された、複数種類の前記金属酸化物を含む金属酸化物群を調製する第１の工程と、
前記金属酸化物群に含まれる前記金属酸化物のそれぞれに対し、それに対応する前記金属元素を選択的に担持させる第２の工程とを含み、
前記第２の工程は、複数種類の前記金属酸化物の等電点の差を利用して、前記金属酸化物群のうちの１種類の前記金属酸化物のみに対してそれに対応する前記金属元素のイオンを選択的に付着させる工程と、前記金属元素のイオンを前記金属元素に変換する工程とを含み、これらの工程からなる多段工程を前記金属酸化物群に含まれる前記金属酸化物の種類毎に繰り返す、
集積化触媒の製造方法。A method for producing an integrated catalyst in which a plurality of types of catalyst units in which a specific metal element is combined with a metal oxide are assembled at a nanometer level,
A first step of preparing a metal oxide group including a plurality of types of the metal oxides integrated at a nanometer level;
For each of the metal oxide contained in the metal oxide group, and a second step of selectively carrying said metal element corresponding thereto,
In the second step, the metal element corresponding to only one type of the metal oxide in the group of metal oxides using a difference in isoelectric points of the plurality of types of the metal oxides. And a step of selectively depositing ions of the metal element and a step of converting ions of the metal element into the metal element, and a multi-stage process consisting of these processes is a kind of the metal oxide included in the metal oxide group Repeat every time,
A method for producing an integrated catalyst .
ナノメートルレベルで集積された、前記三酸化二鉄と前記二酸化スズとを含む水溶液を調製する工程と、
前記水溶液に白金化合物を溶解しかつ前記水溶液のｐＨを前記二酸化スズの等電点よりもアルカリ性側でありかつ前記三酸化二鉄の等電点よりも酸性側に設定して、前記白金化合物からの白金陽イオンを前記二酸化スズのみに選択的に付着させ、前記水溶液のｐＨを前記三酸化二鉄の等電点を越えない範囲でさらにアルカリ性側に調整して前記白金陽イオンから水酸化白金を誘導する工程と、
前記水酸化白金を加熱処理して前記白金元素に変換する工程と、
前記水溶液に金化合物を溶解しかつ前記水溶液のｐＨを前記二酸化スズの等電点と前記三酸化二鉄の等電点との間に設定して、前記金化合物からの金陰イオンを前記三酸化二鉄のみに選択的に付着させ、前記水溶液のｐＨをさらにアルカリ性側に調整して前記金陰イオンから水酸化金を誘導する工程と、
前記水酸化金を加熱処理して前記金元素に変換する工程と、
前記水溶液にランタン塩とイリジウム塩とを溶解した後、前記水溶液のｐＨを調整して、前記水溶液内に水酸化ランタンと水酸化イリジウムとを生成させる工程と、
前記水酸化ランタンおよび前記水酸化イリジウムを加熱処理し、それぞれを前記酸化ランタンおよび前記イリジウム元素に変換する工程と、
を含む集積化触媒の製造方法。The first catalyst unit in which gold element is supported on ferric trioxide, the second catalyst unit in which platinum element is supported on tin dioxide, and the third catalyst unit in which iridium element is supported on lanthanum oxide are included. A method for producing an integrated catalyst comprising a catalyst unit group, wherein the first catalyst component, the second catalyst component, and the third catalyst component are aggregated at a nanometer level to form the catalyst unit group. There,
Preparing an aqueous solution containing the ferric trioxide and the tin dioxide accumulated at the nanometer level;
From the platinum compound, dissolving the platinum compound in the aqueous solution and setting the pH of the aqueous solution to be more alkaline than the isoelectric point of the tin dioxide and more acidic than the isoelectric point of the ferric trioxide. The platinum cation was selectively attached only to the tin dioxide, and the pH of the aqueous solution was further adjusted to the alkaline side within the range not exceeding the isoelectric point of the ferric trioxide to convert the platinum cation to the platinum hydroxide. A step of inducing
Converting the platinum hydroxide to the platinum element by heat treatment;
The gold compound is dissolved in the aqueous solution, and the pH of the aqueous solution is set between the isoelectric point of the tin dioxide and the isoelectric point of the ferric trioxide, so that the gold anion from the gold compound is Selectively adhering only to ferric oxide, and further adjusting the pH of the aqueous solution to the alkaline side to induce gold hydroxide from the gold anion;
Converting the gold hydroxide by heat treatment to the gold element;
After dissolving the lanthanum salt and iridium salt in the aqueous solution, adjusting the pH of the aqueous solution to produce lanthanum hydroxide and iridium hydroxide in the aqueous solution;
Heat treating the lanthanum hydroxide and the iridium hydroxide, and converting each into the lanthanum oxide and the iridium element;
The manufacturing method of the integrated catalyst containing this.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07312999A JP3932335B2 (en) | 1999-03-18 | 1999-03-18 | Integrated catalyst and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07312999A JP3932335B2 (en) | 1999-03-18 | 1999-03-18 | Integrated catalyst and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000262907A JP2000262907A (en) | 2000-09-26 |
| JP3932335B2 true JP3932335B2 (en) | 2007-06-20 |
Family
ID=13509308
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07312999A Expired - Lifetime JP3932335B2 (en) | 1999-03-18 | 1999-03-18 | Integrated catalyst and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3932335B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3752529B2 (en) * | 2001-03-14 | 2006-03-08 | 独立行政法人産業技術総合研究所 | Iridium support material, iridium support method, and iridium support catalyst |
| JP3757267B2 (en) * | 2001-07-23 | 2006-03-22 | 独立行政法人産業技術総合研究所 | Rapid search method for multi-component solid catalysts |
| JP4139883B2 (en) * | 2002-02-08 | 2008-08-27 | 独立行政法人産業技術総合研究所 | Rapid preparation method for various solid catalysts and apparatus therefor |
| JP4038380B2 (en) * | 2002-02-28 | 2008-01-23 | 善雄 村井 | Dioxin decomposition method |
| JP4471191B2 (en) * | 2003-03-28 | 2010-06-02 | 日本ガスケット株式会社 | Method for producing deodorizing catalyst |
| JP4543167B2 (en) * | 2004-03-25 | 2010-09-15 | 独立行政法人産業技術総合研究所 | Deodorant and method for producing the same |
| JP4940421B2 (en) * | 2005-01-17 | 2012-05-30 | 国立大学法人東京工業大学 | Oxide composite material, method for producing the same, electrochemical device, and catalyst containing oxide composite material |
| JP6762269B2 (en) * | 2017-06-15 | 2020-09-30 | 大日精化工業株式会社 | Method for manufacturing catalyst component carrier and catalyst component carrier |
-
1999
- 1999-03-18 JP JP07312999A patent/JP3932335B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000262907A (en) | 2000-09-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1628745B1 (en) | Method and apparatus for purifying air using a photocatalyst | |
| US6855661B2 (en) | Catalyst for purification of diesel engine exhaust gas | |
| TWI442972B (en) | The method of preparation of cerium oxide supported gold-palladium catalysts and its application in destruction of volatile organic compounds | |
| AU2001260735A1 (en) | Catalyst for purification of diesel engine exhaust gas | |
| JP2006507938A (en) | Application of conductive adsorbents, activated carbon granules and carbon fibers as catalytic reaction substrates | |
| TW200927988A (en) | Method for manufacturing high performance photocatalytic filter | |
| CN110404534A (en) | A kind of volatile organic matter catalyst for catalytic oxidation and preparation method thereof of efficient anti-chlorine poisoning | |
| JP2002282689A (en) | Catalyst carrier and catalyst, and method for producing them | |
| JP3932335B2 (en) | Integrated catalyst and method for producing the same | |
| CN113797935A (en) | Catalyst for low-temperature efficient treatment of VOCs and preparation method thereof | |
| JP2004074069A (en) | Formaldehyde oxidation removal method | |
| JP2001187343A (en) | Cleaning catalyst at normal temperature and utilization thereof | |
| JP2007117911A (en) | Catalyst for decomposing organic chlorine compound and method for removing organic chlorine compound using the same | |
| JPH10296087A (en) | Deodorizing catalyst and its manufacture | |
| JP5971136B2 (en) | Carbon monoxide oxidation catalyst, method for producing the same, and method for removing carbon monoxide from gas | |
| JP3310926B2 (en) | DeNOx catalyst and method for producing the same | |
| JPH0290923A (en) | Deodorizing method | |
| JP2001104781A (en) | Material for removing nitrogen oxide and method for removing it | |
| JP5285459B2 (en) | Exhaust gas purification catalyst and exhaust gas purification method | |
| CN110841700A (en) | Mercerized molecular sieve catalyst and preparation method and application thereof | |
| JP2004089953A (en) | Method of continuously decomposing and removing organic substance contained in gas | |
| JP4974004B2 (en) | Particulate matter purification catalyst and particulate matter purification method using the same | |
| CN108236951A (en) | A kind of preparation method of the palladium on carbon powder as formaldehyde remover | |
| JP7165345B2 (en) | Method for decomposing amine-based compound and catalyst for decomposing amine-based compound | |
| TWI293036B (en) | Catalyst, method for producing the same and method for treating volatile organic compounds |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20040405 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20060925 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20061003 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20061130 |
|
| RD02 | Notification of acceptance of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7422 Effective date: 20061130 |
|
| TRDD | Decision of grant or rejection written | ||
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20061130 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20070123 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070216 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20070216 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100330 Year of fee payment: 3 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313117 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100330 Year of fee payment: 3 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| EXPY | Cancellation because of completion of term |