JP2010069471A - Compound oxide catalyst for burning pm, slurry prepared by using the same, and filter for cleaning exhaust gas - Google Patents
Compound oxide catalyst for burning pm, slurry prepared by using the same, and filter for cleaning exhaust gas Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 87
- 239000002002 slurry Substances 0.000 title claims description 12
- 150000001875 compounds Chemical class 0.000 title abstract 3
- 238000004140 cleaning Methods 0.000 title abstract 2
- 238000002485 combustion reaction Methods 0.000 claims description 77
- 239000002131 composite material Substances 0.000 claims description 47
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 34
- 239000010436 fluorite Substances 0.000 claims description 31
- 239000013078 crystal Substances 0.000 claims description 26
- 229910052746 lanthanum Inorganic materials 0.000 claims description 16
- 238000000746 purification Methods 0.000 claims description 15
- 229910052697 platinum Inorganic materials 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 11
- 229910052788 barium Inorganic materials 0.000 claims description 10
- 229910052797 bismuth Inorganic materials 0.000 claims description 9
- 229910052712 strontium Inorganic materials 0.000 claims description 9
- 229910052726 zirconium Inorganic materials 0.000 claims description 9
- 230000003647 oxidation Effects 0.000 claims description 7
- 238000007254 oxidation reaction Methods 0.000 claims description 7
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 6
- 229910052779 Neodymium Inorganic materials 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- 229910052763 palladium Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 229910052684 Cerium Inorganic materials 0.000 claims description 5
- 229910052772 Samarium Inorganic materials 0.000 claims description 5
- 229910052703 rhodium Inorganic materials 0.000 claims description 5
- 229910052715 tantalum Inorganic materials 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 229910052733 gallium Inorganic materials 0.000 claims description 3
- 229910052738 indium Inorganic materials 0.000 claims description 3
- 229910052700 potassium Inorganic materials 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 229910052727 yttrium Inorganic materials 0.000 claims description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 44
- 229910052717 sulfur Inorganic materials 0.000 abstract description 44
- 239000011593 sulfur Substances 0.000 abstract description 44
- 230000000694 effects Effects 0.000 abstract description 15
- 239000000470 constituent Substances 0.000 abstract description 6
- 239000013618 particulate matter Substances 0.000 abstract description 6
- 229910000510 noble metal Inorganic materials 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 70
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 36
- 230000000052 comparative effect Effects 0.000 description 29
- 208000005374 Poisoning Diseases 0.000 description 22
- 231100000572 poisoning Toxicity 0.000 description 22
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- 238000000034 method Methods 0.000 description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 239000000843 powder Substances 0.000 description 16
- 239000010936 titanium Substances 0.000 description 16
- 239000002243 precursor Substances 0.000 description 14
- 230000002378 acidificating effect Effects 0.000 description 13
- 239000006229 carbon black Substances 0.000 description 13
- 229910052760 oxygen Inorganic materials 0.000 description 13
- 239000000523 sample Substances 0.000 description 13
- 239000007864 aqueous solution Substances 0.000 description 12
- 239000001301 oxygen Substances 0.000 description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 229910002091 carbon monoxide Inorganic materials 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 238000011156 evaluation Methods 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 8
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- 238000001179 sorption measurement Methods 0.000 description 8
- 238000001914 filtration Methods 0.000 description 7
- 239000000446 fuel Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 235000011114 ammonium hydroxide Nutrition 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- 239000004570 mortar (masonry) Substances 0.000 description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 238000003860 storage Methods 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 239000010948 rhodium Substances 0.000 description 5
- 239000012488 sample solution Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000002411 thermogravimetry Methods 0.000 description 5
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Chemical compound [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 4
- 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 4
- 239000011812 mixed powder Substances 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 229910000420 cerium oxide Inorganic materials 0.000 description 3
- 238000004455 differential thermal analysis Methods 0.000 description 3
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 3
- RXPAJWPEYBDXOG-UHFFFAOYSA-N hydron;methyl 4-methoxypyridine-2-carboxylate;chloride Chemical compound Cl.COC(=O)C1=CC(OC)=CC=N1 RXPAJWPEYBDXOG-UHFFFAOYSA-N 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 3
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000008929 regeneration Effects 0.000 description 3
- 238000011069 regeneration method Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000010532 solid phase synthesis reaction Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 229910000416 bismuth oxide Inorganic materials 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 229910052878 cordierite Inorganic materials 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- TYIXMATWDRGMPF-UHFFFAOYSA-N dibismuth;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Bi+3].[Bi+3] TYIXMATWDRGMPF-UHFFFAOYSA-N 0.000 description 2
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
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- 230000007246 mechanism Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- PLDDOISOJJCEMH-UHFFFAOYSA-N neodymium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Nd+3].[Nd+3] PLDDOISOJJCEMH-UHFFFAOYSA-N 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- -1 oxygen ion Chemical class 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000004445 quantitative analysis Methods 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910000505 Al2TiO5 Inorganic materials 0.000 description 1
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- 206010017740 Gas poisoning Diseases 0.000 description 1
- 229910002147 La0.6Sr0.4FeO3 Inorganic materials 0.000 description 1
- 229910002204 La0.8Sr0.2MnO3 Inorganic materials 0.000 description 1
- 230000010718 Oxidation Activity Effects 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
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- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
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- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
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- 229910001938 gadolinium oxide Inorganic materials 0.000 description 1
- 229940075613 gadolinium oxide Drugs 0.000 description 1
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910003465 moissanite Inorganic materials 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- UJVRJBAUJYZFIX-UHFFFAOYSA-N nitric acid;oxozirconium Chemical compound [Zr]=O.O[N+]([O-])=O.O[N+]([O-])=O UJVRJBAUJYZFIX-UHFFFAOYSA-N 0.000 description 1
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- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明はＰＭ燃焼用複合酸化物触媒、それを用いたスラリー及び排ガス浄化用フィルターに係り、更に詳細には、自動車用途を始めとした、ディーゼル機関等から排出される粒子状物質（以下、「ＰＭ」（Ｐａｒｔｉｃｕｌａｔｅ Ｍａｔｔｅｒ）と記載する場合がある。）を燃焼するためのＰＭ燃焼用複合酸化物触媒、それを用いたスラリー及び排ガス浄化用フィルターに関する。 The present invention relates to a composite oxide catalyst for PM combustion, a slurry using the same, and a filter for purifying exhaust gas. More specifically, the present invention relates to particulate matter discharged from diesel engines and the like (hereinafter referred to as “ The present invention relates to a PM complex oxide catalyst for burning “PM” (sometimes referred to as “Particulate Matter”), a slurry using the same, and an exhaust gas purification filter.
近年、ディーゼル機関の排気ガスに含まれる環境汚染物質としての窒素酸化物（ＮＯX）及びＰＭが問題となっている。このうちＰＭは、カーボンを主体とする微粒子であって、通常はその除去方法として、その構造内に微細な空孔を有するディーゼル・パティキュレート・フィルター（以下「ＤＰＦ」と記載する場合がある）を通過させることによって、「漉し取る」方法が多用されている。ただ、この方法でＰＭを分離除去する場合、ある程度ＰＭの堆積が進むと、ガスがＤＰＦに導入される際に生じる圧損が大きくなり、ディーゼル機関そのものにも負荷がかかるようになる。従って、かような方法を使用してＰＭを除去する方法を採用する際には、間欠、又は連続的にこのＰＭを強制燃焼により除去する必要がある。 In recent years, nitrogen oxides (NO x ) and PM as environmental pollutants contained in exhaust gas from diesel engines have become a problem. Among these, PM is a fine particle mainly composed of carbon, and as a method for removing it, a diesel particulate filter having fine pores in its structure (hereinafter sometimes referred to as “DPF”) may be used. The method of “squeezing out” is often used by passing the filter. However, when PM is separated and removed by this method, if PM is accumulated to some extent, the pressure loss generated when the gas is introduced into the DPF increases, and the diesel engine itself is loaded. Therefore, when adopting a method for removing PM using such a method, it is necessary to remove the PM intermittently or continuously by forced combustion.
このようなＤＰＦからのＰＭ除去処理には、電気ヒーターやバーナー等を設置して外部加熱によりＰＭを燃焼させる方法、ＤＰＦから向かってエンジン側に酸化触媒を設置し、排気ガス中のＮＯを当該酸化触媒によりＮＯ2とし、当該ＮＯ2の酸化力によりＰＭを燃焼させる方法、ＤＰＦにＮＯX吸蔵触媒を共存し、空燃比によるＮＯXの吸放出の際生じる活性酸素によりＰＭを燃焼させる方法など、がある。 In such PM removal processing from DPF, an electric heater, a burner or the like is installed to burn PM by external heating, an oxidation catalyst is installed on the engine side from the DPF, and NO in the exhaust gas is removed. and NO 2 by the oxidation catalyst, a method for burning PM by the oxidation force of the NO 2, and coexist the NO X storage catalyst DPF, the active oxygen produced during the absorption and desorption of the NO X by the air-fuel ratio and a method for combusting PM There is.
ただし、従来から検討されている方法には一長一短がある。まず、電気ヒーターやバーナー等を設置する方法は、外部からエネルギーを加える必要がありシステム及びＤＰＦの再生が煩雑化するという問題があった。次に、酸化触媒を設置する方法については、酸化触媒の活性適正温度に比べ、運転時の排気ガス温度が低いことから、触媒の活性点にまで達せずに、ＮＯからＮＯ2への反応促進が起こりづらいことから、ＮＯを酸化してＰＭ燃焼に必要な量のＮＯ2を排気ガス中に確保できないという問題があった。 However, there are merits and demerits in the methods that have been studied conventionally. First, the method of installing an electric heater, a burner or the like has a problem that it is necessary to apply energy from the outside, and the regeneration of the system and the DPF becomes complicated. Next, with regard to the method of installing an oxidation catalyst, since the exhaust gas temperature during operation is lower than the appropriate activation temperature of the oxidation catalyst, the reaction from NO to NO 2 is promoted without reaching the active point of the catalyst. Therefore, there is a problem in that it is impossible to oxidize NO and secure the amount of NO 2 required for PM combustion in the exhaust gas.
また、今後は環境的側面から、エンジンから発生する窒素酸化物の発生そのものが低減されるようになると考えられる。ともすれば、従来のＰＭ燃焼除去方法において、ＮＯ2の発生を念頭に置いた方法は利用が困難になると想像される。また、ＮＯX吸蔵触媒を共存させる方法では、排気ガス中に含まれる硫黄酸性ガスが触媒粒子と反応することによって引き起こされる、触媒のＰＭ燃焼補助性能の劣化、いわゆる硫黄被毒現象によって、ＰＭ燃焼活性も低下することが多いという問題があった。 In the future, it is considered that the generation of nitrogen oxides generated from the engine itself will be reduced from the environmental aspect. Therefore, in the conventional PM combustion removal method, it is imagined that the method with the generation of NO 2 in mind becomes difficult to use. Further, in the method in which the NO x storage catalyst coexists, the PM combustion is caused by the deterioration of the PM combustion auxiliary performance of the catalyst caused by the reaction of the sulfur acidic gas contained in the exhaust gas with the catalyst particles, so-called sulfur poisoning phenomenon. There was a problem that the activity often decreased.
こうした触媒使用方式のうち、この点に着目した排気ガス中に含まれる硫黄被毒に耐えうるＰＭ燃焼除去補助触媒としては、例えば特許文献１には、Ｐｔを担持したＤＰＦが開示されている。 Among such catalyst usage methods, for example, Patent Document 1 discloses a DPF carrying Pt as a PM combustion removal auxiliary catalyst that can withstand sulfur poisoning contained in exhaust gas, focusing on this point.
また、特許文献２には、触媒として白金族金属元素を含まないジルコニウム系複合酸化物やセリウム系複合酸化物が開示されている。これらの複合酸化物は酸素イオン導電性により、活性酸素（Ｏ2-）を放出するため、この活性酸素がＰＭを低温で燃焼するとされている。 Patent Document 2 discloses a zirconium-based composite oxide or a cerium-based composite oxide that does not contain a platinum group metal element as a catalyst. Since these complex oxides release active oxygen (O 2− ) due to oxygen ion conductivity, this active oxygen is supposed to burn PM at a low temperature.
本発明者らの検討によると、特許文献１に記載された方法では、ＮＯをＮＯ2に酸化する能力が高く、ＮＯ2を利用したＰＭの燃焼作用も期待できるが、Ｐｔ族元素は希少金属であり、金属市場の影響を受けやすく、使用する量が少量といえどもコストの変動要因として看過できない状況にある。更に、前述したとおり、Ｐｔを用いてＮＯからＮＯ2へ変換する方式そのものが、将来的にはＮＯXに対する排出ガス規制の強化により排ガス中のＮＯXが削減されることに伴い、ＰＭ燃焼に必要十分なＮＯ2が得られず、存立自体が危ぶまれる可能性がある。 According to the study by the present inventors, the method described in Patent Document 1 has a high ability to oxidize NO to NO 2 and can be expected to have a PM combustion action using NO 2 , but Pt group elements are rare metals. It is easily affected by the metal market, and even if the amount used is small, it cannot be overlooked as a cost fluctuation factor. Further, as described above, method itself for converting NO to NO 2 with Pt is, along with the NO X in the exhaust gas is reduced by the strengthening of exhaust gas regulations for NO X in the future, the PM combustion Necessary and sufficient NO 2 cannot be obtained, and the existence itself may be jeopardized.
一方、特許文献２に記載されているＰＭ燃焼触媒は、比較的低い温度でＰＭを燃焼することができるとされている。しかし、本発明者らが検討したところによると、当該触媒は、燃料中、更には排気ガス中に含まれる硫黄成分が吸着することにより被毒しＰＭ燃焼活性が低下しやすいことがわかった。 On the other hand, the PM combustion catalyst described in Patent Document 2 is supposed to be able to burn PM at a relatively low temperature. However, according to a study by the present inventors, it has been found that the catalyst is poisoned by the adsorption of sulfur components contained in the fuel and further in the exhaust gas, and the PM combustion activity tends to be lowered.
本発明は、このような従来技術の有する課題に鑑みてなされたものであり、その目的とは、ディーゼルエンジンの排気ガス中に含まれる硫黄酸性ガスによるＰＭ燃焼活性の低下を抑制しつつ、ＰＭを低温で燃焼させ得るＰＭ燃焼用複合酸化物触媒、それを用いたスラリー及び排ガス浄化用フィルターを提供することにある。 This invention is made | formed in view of the subject which such a prior art has, and the objective is suppressing the fall of PM combustion activity by the sulfur acidic gas contained in the exhaust gas of a diesel engine, and PM. Is to provide a composite oxide catalyst for PM combustion that can be combusted at a low temperature, a slurry using the catalyst, and a filter for exhaust gas purification.
本発明者らは、前記課題を解決するため鋭意研究を重ねた結果、ペロブスカイト型格子を構成単位として含み、層状構造を有する複合酸化物を触媒活性成分として用いることにより、上記課題が解決できることを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventors have found that the above problem can be solved by using a composite oxide having a perovskite lattice as a structural unit and having a layered structure as a catalytically active component. The headline and the present invention were completed.
また、このＰＭ燃焼用複合酸化物触媒の層状構造の構成は、フルオライト層とペロブスカイト層が交互に積層した結晶構造を有することが好ましい。更に、このフルオライト層にはＢｉ、Ｌａ、Ｃｅ、Ｚｒから選ばれる少なくとも１種以上の元素を含むことが好ましい。また、このＰＭ燃焼用複合酸化物触媒は、組成式がＢｉ2Ａn-1ＢnＯ3n+3（但し、ｎは１以上の整数。「Ａ」はＮａ、Ｋ、Ｃａ、Ｓｒ、Ｂａ、Ｙ、Ｌａ、Ｐｒ、Ｎｄ、Ｓｍ、Ｇｄ、Ｂｉ、Ａｇの中から選ばれる１種以上の元素を含み、「Ｂ」はＴｉ、Ｆｅ、Ｚｒ、Ｎｂ、Ｍｏ、Ｔａ、Ｗ、Ａｌ、Ｇａ、Ｉｎ、Ｐｄ、Ｐｔ、Ｒｈの中から選ばれる１種以上の元素を含む）で表されるＡｕｒｉｖｉｌｌｉｕｓ（以下「アウリビリウス」という。）型結晶構造酸化物であることが好ましい。さらに、フルオライト層とペロブスカイト層の結合面におけるフルオライト格子とペロブスカイト格子の格子定数が整数倍であることが好ましい。 The layered structure of the PM combustion composite oxide catalyst preferably has a crystal structure in which fluorite layers and perovskite layers are alternately stacked. Furthermore, this fluorite layer preferably contains at least one element selected from Bi, La, Ce, and Zr. The composite oxide catalyst for PM combustion has a composition formula of Bi 2 A n-1 B n O 3n + 3 (where n is an integer of 1 or more. “A” is Na, K, Ca, Sr, Ba) , Y, La, Pr, Nd, Sm, Gd, Bi, and Ag, and “B” includes Ti, Fe, Zr, Nb, Mo, Ta, W, Al, Ga. , In, Pd, Pt, and Rh, including an Aurivirillis (hereinafter referred to as “Aurivirius”) type crystal structure oxide. Furthermore, it is preferable that the lattice constant of the fluorite lattice and the perovskite lattice at the bonding surface between the fluorite layer and the perovskite layer is an integer multiple.
一方、本発明のスラリーは、上述のＰＭ燃焼用複合酸化物触媒を用いたことを特徴とする。 On the other hand, the slurry of the present invention is characterized by using the above-mentioned composite oxide catalyst for PM combustion.
他方、本発明の排ガス浄化用フィルターは、上述のＰＭ燃焼用複合酸化物触媒をディーゼルパティキュレートフィルター上に配設してなることを特徴とする。また、Ｐｔ、Ｒｈ及びＰｄから選ばれる元素の少なくとも１種を含有することが好ましい。 On the other hand, the exhaust gas purifying filter of the present invention is characterized in that the above-mentioned PM combustion composite oxide catalyst is disposed on a diesel particulate filter. Moreover, it is preferable to contain at least one element selected from Pt, Rh and Pd.
本発明によれば、ペロブスカイト型格子を構成単位として含み、層状構造を有する複合酸化物を用いることとしたため、ディーゼルエンジン排気ガス中に含まれる硫黄酸性ガスによるＰＭ燃焼活性の低下を抑制しつつ、ＰＭを低温で燃焼させ得るＰＭ燃焼用複合酸化物触媒、それを用いたスラリー及び排ガス浄化用フィルターを提供できる。 According to the present invention, since the composite oxide including a perovskite lattice as a structural unit and having a layered structure is used, while suppressing a decrease in PM combustion activity due to sulfur acidic gas contained in diesel engine exhaust gas, It is possible to provide a PM complex oxide catalyst capable of burning PM at a low temperature, a slurry using the catalyst, and an exhaust gas purification filter.
以下、本発明のＰＭ燃焼用複合酸化物触媒について詳細に説明する。本発明のＰＭ燃焼用複合酸化物触媒は、ペロブスカイト型格子を構成単位として含む層状構造酸化物である。 Hereinafter, the composite oxide catalyst for PM combustion of the present invention will be described in detail. The complex oxide catalyst for PM combustion of the present invention is a layered structure oxide containing a perovskite lattice as a structural unit.
このような複合酸化物を触媒として、ディーゼル排ガス浄化用フィルターに用いれば、従来の酸化触媒を用いたフィルターに比べ、硫黄酸性ガスの被毒によるＰＭ燃焼活性の低下が抑制されるため、継続してＰＭを低温で燃焼させうる。言い換えれば、上記複合酸化物触媒を用いることで、硫黄に対する耐性が担保され、ＰＭ燃焼活性の低下が抑制されるので、長期にわたりＰＭ燃焼活性を維持できる。 If such a composite oxide is used as a catalyst in a diesel exhaust gas purification filter, the decrease in PM combustion activity due to sulfur acid gas poisoning is suppressed as compared with a filter using a conventional oxidation catalyst. PM can be burned at a low temperature. In other words, by using the composite oxide catalyst, resistance to sulfur is ensured, and a decrease in PM combustion activity is suppressed, so that PM combustion activity can be maintained over a long period of time.
ここで、上記ＰＭ燃焼用複合酸化物は、フルオライト層とペロブスカイト層が交互に積層した結晶構造酸化物であることが好ましい。また、このフルオライト層はＢｉ、Ｌａ、Ｃｅ又はＺｒ及びこれら元素を任意に組合せたものを含むことが好ましい。 Here, the PM combustion composite oxide is preferably a crystal structure oxide in which a fluorite layer and a perovskite layer are alternately stacked. The fluorite layer preferably contains Bi, La, Ce or Zr and any combination of these elements.
代表的な組成式がＢｉ2Ａn-1ＢnＯ3n+3（但し、ｎは１以上の整数）で表されるアウリビリウス型結晶構造をとる酸化物であることが好ましい。これは、構成単位であるフルオライト層［Ｂｉ2Ｏ2］2+とペロブスカイト層［Ａn-1ＢnＯ3n+1］2-をまとめて表記したものである。 Typical Bi 2 A n-1 composition formula B n O 3n + 3 (where, n is an integer of 1 or more) is preferably an oxide taking Auribiriusu type crystal structure represented by. This is a collective representation of the fluorite layer [Bi 2 O 2 ] 2+ and the perovskite layer [A n-1 B n O 3n + 1 ] 2− which are constituent units.
本発明でいうアウリビリウス型結晶構造とは、結晶構造中の少なくとも１種以上の元素が部分的に欠損した結果、上記組成式から乖離する量論比であったとしても、Ｘ線回折によりアウリビリウス型結晶構造を有すると確認できるようなものを含む。なお、「アウリビリウス型結晶構造」とは、単にアウリビリウス型結晶物質の単一相を示すだけでなく、一部にアウリビリウス型結晶構造とは異なる相を含むような物質でもよい。 The auribilius type crystal structure as used in the present invention is an auribilius type crystal by X-ray diffraction even if the stoichiometric ratio deviates from the above composition formula as a result of partial loss of at least one element in the crystal structure. Includes those that can be confirmed to have a crystal structure. In addition, the “Auribilius type crystal structure” may not only indicate a single phase of the Auribilius type crystal substance, but may also be a substance partially including a phase different from the Auribilius type crystal structure.
図４にアウリビリウス型結晶構造を示す。符号１００の部分はフルオライト層を示す。黒丸５０はＢｉで白丸５１は酸素である。ここでは、Ｂｉと酸素が最密充填の関係に位置している。符号１１０の部分はペロブスカイト層を示す。符号１１０の部分の八面体５２は、Ｂサイト元素に酸素が６配位した格子（以下「ＢＯ6八面体格子」という）を示しており、また、ＢＯ6八面体格子同士は頂点同士を共有し、ＢＯ6八面体格子同士の間の隙間にＡサイトがある構造である。ペロブスカイト層との境界に位置するＢｉはフルオライト層と共有となっている。 FIG. 4 shows an Aurivirius crystal structure. Reference numeral 100 indicates a fluorite layer. The black circle 50 is Bi and the white circle 51 is oxygen. Here, Bi and oxygen are in a close-packed relationship. Reference numeral 110 indicates a perovskite layer. The octahedron 52 at 110 is a lattice in which oxygen is six-coordinated to the B site element (hereinafter referred to as “BO 6 octahedral lattice”), and the BO 6 octahedral lattices share vertices. In this structure, there is an A site in the gap between the BO 6 octahedral lattices. Bi located at the boundary with the perovskite layer is shared with the fluorite layer.
上述のＢｉ2Ａn-1ＢnＯ3n+3の「Ａ」は、ペロブスカイト層のＡサイトに位置する元素を表し、「Ｂ」はＢサイトに位置する元素を表す。ｎはフルオライト層とペロブスカイト層の積層方向におけるＢＯ6八面体格子の積層数を示している。例えば、図４は、ｎ＝４の場合に相当する。ｎは１以上の整数である。また、Ａサイト及びＢサイトに位置する元素は電荷のバランスによって決定され、前述した組成式の「Ａ」及び「Ｂ」で表される元素の量論的な陽イオンの価数の和がｎの６倍であれば、ＡサイトもしくはＢサイトは単独の元素からなるだけでなく、構成元素の一部を他の元素に置換してもよい。 In the above-described Bi 2 A n-1 B n O 3n + 3 , “A” represents an element located at the A site of the perovskite layer, and “B” represents an element located at the B site. n indicates the number of stacked BO 6 octahedral lattices in the stacking direction of the fluorite layer and the perovskite layer. For example, FIG. 4 corresponds to the case of n = 4. n is an integer of 1 or more. The elements located at the A site and the B site are determined by the balance of charges, and the sum of the valences of the stoichiometric cations of the elements represented by “A” and “B” in the above-described composition formula is n. If it is 6 times, the A site or the B site is not only composed of a single element, but a part of the constituent elements may be replaced with another element.
例えば、ｎ＝１の場合において、Ｂｉ2ＭＯ6（ここでＭ＝Ｍｏ、Ｗ）などがあり、ｎ＝２の場合において、Ｂｉ2ＡｅＭ2Ｏ9（ここでＡｅ＝Ｂａ、Ｓｒ、Ｃａ、Ｍ＝Ｎｂ、Ｔａ）などがあり、ｎ＝３の場合において、Ｂｉ2Ｌｎ2Ｔｉ3Ｏ12など（ここでＬｎ＝Ｌａ、Ｓｍなど）があり、ｎ＝４の場合において、Ｂｉ2ＣａＢｉ2Ｔｉ4Ｏ15などがあり、ｎ＝５の場合において、Ｂｉ2Ｐｒ2Ｂｉ2Ｔｉ3Ｆｅ2Ｏ18などがあげられる。 For example, when n = 1, there are Bi 2 MO 6 (where M = Mo, W), and when n = 2, Bi 2 AeM 2 O 9 (where Ae = Ba, Sr, Ca, M = Nb, Ta) and the like, and when n = 3, there are Bi 2 Ln 2 Ti 3 O 12 and the like (where Ln = La, Sm, etc.), and when n = 4, Bi 2 CaBi 2 Ti 4 O 15 and the like, and in the case of n = 5, Bi 2 Pr 2 Bi 2 Ti 3 Fe 2 O 18 and the like can be mentioned.
加えて、Ｂｉ2Ｎａ0.5Ｂｉ0.5Ｎｂ2Ｏ9などや、Ｂｉ2ＬｎＳｒＴｉ2ＭＯ12など（ここでＬｎ＝Ｌａ、Ｓｍ、Ｍ＝Ｎｂ、Ｔａ）のように、イオン半径が近い元素であれば、電荷のバランスを保持した上で、異なる２種類以上の価数の元素をＡサイト及びＢサイトに任意に置換することができる。 In addition, if the element has a close ionic radius, such as Bi 2 Na 0.5 Bi 0.5 Nb 2 O 9 or Bi 2 LnSrTi 2 MO 12 (where Ln = La, Sm, M = Nb, Ta) In addition, while maintaining the charge balance, two or more different valence elements can be arbitrarily substituted into the A site and the B site.
特に、ＰＭの燃焼温度を低温化するためには、Ｎａ、Ｋ、Ｃａ、Ｓｒ、Ｂａ、Ｙ、Ｌａ、Ｐｒ、Ｎｄ、Ｓｍ、Ｇｄ、Ｂｉ、Ａｇの中から選ばれる１種以上の元素がペロブスカイト格子のＡサイトの５０％以上を占有していれば好ましく、Ｔｉ、Ｆｅ、Ｚｒ、Ｎｂ、Ｍｏ、Ｔａ、Ｗ、Ａｌ、Ｇａ、Ｉｎ、Ｐｄ、Ｐｔ、Ｒｈの中から選ばれる１種以上の元素がペロブスカイト格子のＢサイトの５０％以上を占有していることが好ましい。 In particular, in order to lower the combustion temperature of PM, one or more elements selected from Na, K, Ca, Sr, Ba, Y, La, Pr, Nd, Sm, Gd, Bi, and Ag are used. Preferably, it occupies 50% or more of the A site of the perovskite lattice, and one or more selected from Ti, Fe, Zr, Nb, Mo, Ta, W, Al, Ga, In, Pd, Pt, and Rh These elements preferably occupy 50% or more of the B site of the perovskite lattice.
Ｂサイト元素の主成分をＴｉ、Ｗ、Ｎｂ、Ｔａとした場合、価数がひとつ異なる元素でイオン半径が近いものであれば、Ｂサイトに置換できる。その際の電荷のバランスはＡサイト元素で調節する場合とＢｉサイトで調節する場合が可能である。Ｂｉサイトで調整した場合、上述のＢｉ2Ａn-1ＢnＯ3n+3の「Ｂｉ2」が「Ｂｉ2-x」となるが本発明に該当する層状複合酸化物として使用できる。 When the main component of the B-site element is Ti, W, Nb, or Ta, an element having a different valence and a close ionic radius can be substituted with the B site. In this case, the charge balance can be adjusted by the A site element or by the Bi site. When adjusted at the Bi site, “Bi 2 ” of the above-mentioned Bi 2 An n-1 B n O 3n + 3 becomes “Bi 2-x ”, but it can be used as a layered composite oxide corresponding to the present invention.
ＤＰＦから向かってエンジン側にＮＯｘ吸蔵還元触媒を用いることがある。ＮＯｘ吸蔵還元触媒の再生時には燃料を噴霧し、燃料の燃焼熱によって排ガス温度を高めると同時に、還元性ガスの濃度を高める必要がある。そのため、ＮＯｘ吸蔵還元触媒から向かって大気開放側にあるＤＰＦ触媒は定期的に高温の排ガスに曝されることになる。 A NOx occlusion reduction catalyst may be used on the engine side from the DPF. At the time of regeneration of the NOx storage reduction catalyst, it is necessary to spray the fuel and raise the exhaust gas temperature by the combustion heat of the fuel and at the same time increase the concentration of the reducing gas. Therefore, the DPF catalyst on the open side to the atmosphere from the NOx storage reduction catalyst is periodically exposed to high-temperature exhaust gas.
発明者らが検討した結果、フルオライト構造を有する酸化Ｂｉは、ＰＭの燃焼に活性を示すものの、上述のＮＯｘ吸蔵還元触媒の再生時の排ガス雰囲気の変動の際に、フルオライト構造の崩壊が生じ、触媒活性が熱により低下することが分かった。これに対して、当該層状複合酸化物においてペロブスカイト層と酸化Ｂｉ層の結合面におけるペロブスカイト格子と酸化Ｂｉ格子の格子定数が整数倍であると、酸化Ｂｉ層がペロブスカイト層と強固に結合して、高温の排ガスに曝された際に、酸化Ｂｉの劣化を回避できる。ペロブスカイト層の厚みに相当するｎ数が、局所的に異なる積層構造複合酸化物でも同様の効果が期待できる。このような局所的なｎ数の変化は高倍率の透過型電子顕微鏡を用いて、結晶構造内の原子配列を観察するなどの方法により分かる。 As a result of investigations by the inventors, although the oxidized Bi having a fluorite structure is active in the combustion of PM, the fluorite structure collapses when the exhaust gas atmosphere changes during regeneration of the NOx storage reduction catalyst described above. It was found that the catalytic activity was reduced by heat. On the other hand, when the lattice constant of the perovskite lattice and the oxidized Bi lattice at the bonding surface of the perovskite layer and the oxidized Bi layer is an integer multiple in the layered composite oxide, the oxidized Bi layer is firmly bonded to the perovskite layer, Deterioration of oxidized Bi can be avoided when exposed to high temperature exhaust gas. A similar effect can be expected even with a multilayer structure oxide having locally different n numbers corresponding to the thickness of the perovskite layer. Such a local change in n number can be understood by a method such as observing the atomic arrangement in the crystal structure using a high-power transmission electron microscope.
このようにアウリビリウス型結晶構造の幾何学的な制約及び電荷のバランスを満たす限り、様々な元素をペロブスカイト層のＡサイト及びＢサイトの構成元素とすることができる。 As described above, various elements can be used as constituent elements of the A site and the B site of the perovskite layer as long as the geometrical constraints and the charge balance of the Aurillius crystal structure are satisfied.
また、ペロブスカイト層を構成する元素の硫酸塩の熱分解温度が低いほうが硫黄酸性ガスとの親和性を低下させることができ、触媒の失活を抑制することができるので好ましい。特にＡサイト元素はＢｉを主成分とする構成が好ましく、Ｂサイト元素はＴｉを主成分とする構成が好ましい。またペロブスカイト構造のうち、一部の成分をＬａ、Ｂａ、Ｃａ、Ｓｒ、Ｆｅに置換する構成にしても構わない。このとき、ＡサイトのＢｉを置換できる元素はＬａ、Ｂａ、Ｃａ、Ｓｒであり、ＢサイトのＴｉを置換できるのはＦｅである。このような組成の組み合わせにすることにより、排ガス中の硫黄酸性ガスの吸着によるＰＭの燃焼活性の低下を抑制できる。 In addition, it is preferable that the thermal decomposition temperature of the sulfate of the element constituting the perovskite layer is lower because the affinity with the sulfur acidic gas can be reduced and the deactivation of the catalyst can be suppressed. In particular, the A-site element is preferably composed mainly of Bi, and the B-site element is preferably composed mainly of Ti. Moreover, you may make it the structure which replaces a part component in a perovskite structure with La, Ba, Ca, Sr, and Fe. At this time, elements that can replace Bi at the A site are La, Ba, Ca, and Sr, and Ti that can replace Ti at the B site is Fe. By using such a combination of compositions, it is possible to suppress a decrease in PM combustion activity due to adsorption of sulfur acidic gas in the exhaust gas.
更に、本発明のＰＭ燃焼用複合酸化物触媒は、亜硫酸ガスに対する酸化活性が低い。即ち硫黄含有ガスによる被毒を受けにくい。後述の実験データで明らかなように、当該複合酸化物表面では硫黄の吸着が非常に起こりにくい。 Furthermore, the complex oxide catalyst for PM combustion of the present invention has low oxidation activity for sulfurous acid gas. That is, it is difficult to be poisoned by the sulfur-containing gas. As will be apparent from the experimental data described later, sulfur adsorption is very difficult to occur on the surface of the composite oxide.
これは、亜硫酸ガス（ＳＯ2）の吸着が起こるメカニズムが、含酸素雰囲気下において、ＳＯ2が触媒表面に吸着し、次いで酸化されＳＯ3となり、当該ＳＯ3が不安定なため、安定化するために硫酸塩などの形状をとって吸着するためであると考えられる。 This is because the mechanism of adsorption of sulfurous acid gas (SO 2 ) is stabilized because SO 2 is adsorbed on the catalyst surface in an oxygen-containing atmosphere and then oxidized to SO 3 , so that SO 3 is unstable. Therefore, it is thought that it is because it takes a shape such as sulfate and adsorbs.
詳細なメカニズムは現時点では明らかではないが、本発明に係るＰＭ燃焼用複合酸化物では、フルオライト層、ペロブスカイト層のいずれか一方又は双方に硫黄酸化性ガス（ＳＯｘ）に対する親和性が低い酸性元素を選択的に組み込むことができ、この場合、かかる複合酸化物の露出面には酸性元素を含む面（フルオライト層）と含まない面（ペロブスカイト層）がストライプ状に配列した積層構造が現れることとなる。 Although the detailed mechanism is not clear at present, in the complex oxide for PM combustion according to the present invention, either or both of the fluorite layer and the perovskite layer is an acidic element having a low affinity for sulfur oxidizing gas (SOx). In this case, the exposed surface of such a complex oxide has a stacked structure in which a surface containing an acidic element (fluorite layer) and a surface not containing (perovskite layer) are arranged in a stripe pattern. It becomes.
かかる酸性元素が存在するフルオライト層及びこの層とペロブスカイト層の境界付近では硫黄酸化性ガスの親和性が低下し、硫黄の吸着が抑制されると推察できる。特にペロブスカイト層のｎ数が小さい、言い換えればフルオライト層とペロブスカイト層の積層周期が短い（ストライプの幅が狭い）と、ＳＯｘが酸性元素を含むフルオライト層に遭遇する確率が高くなるのでより効果的であると考えられる。 It can be inferred that the affinity of the sulfur oxidizing gas is reduced in the vicinity of the fluorite layer in which such an acidic element is present and the boundary between this layer and the perovskite layer, and sulfur adsorption is suppressed. In particular, if the n-number of the perovskite layer is small, in other words, if the stacking period of the fluorite layer and the perovskite layer is short (the width of the stripe is narrow), the probability that SOx encounters a fluorite layer containing an acidic element is increased, so that the effect is higher. It is considered to be appropriate.
なお、一般的にＳ対策として、酸性元素を触媒表面に分散させたり、結晶構造中に固溶させたりすることがあるが、酸性元素がＰＭ燃焼に不活性であるのに触媒表面に分散させると、触媒とＰＭの接触が妨げられることがあり、また、固溶させると酸性元素が触媒表面に露出せず、うまく機能しないことがある。更に、熱処理によって、酸性元素が凝集したりして、熱劣化してしまうことも考えられる。即ち、従来からの一般的な硫黄含有ガスへの被毒防止の対策では、触媒表面の酸点の分布を制御することは難しい。そのため、本願発明のような、組成の面からの改善が最も好ましい形態である。 In general, as an S countermeasure, an acidic element may be dispersed on the catalyst surface or dissolved in the crystal structure, but the acidic element is dispersed on the catalyst surface even though it is inactive to PM combustion. Then, contact between the catalyst and PM may be hindered, and when dissolved, the acidic element may not be exposed on the catalyst surface and may not function well. Furthermore, it is conceivable that the heat treatment causes the acidic elements to aggregate due to heat treatment. That is, it is difficult to control the distribution of acid sites on the catalyst surface by conventional measures for preventing poisoning of a general sulfur-containing gas. Therefore, the improvement from the aspect of composition like this invention is the most preferable form.
続いて、本発明のＰＭ燃焼用複合酸化物触媒をスラリー化して塗布し、ＤＰＦ上に配設して得られる排ガス浄化用フィルターについて説明する。 Next, an exhaust gas purification filter obtained by slurrying and applying the PM combustion composite oxide catalyst of the present invention and disposing it on the DPF will be described.
まず、当該複合酸化物の粒度を調整し、コージェライトやＳｉＣ等の、ＤＰＦ基材の細孔径やＤＰＦの内壁表面の粗さに適した粒度とする。次に、粒度を調整した当該複合酸化物を、純水などの溶媒に分散しスラリーを製造する。当該スラリーを、含浸などの一般的な方法を用いてＤＰＦ内壁と接触させる。当該接触の後、溶媒である水分を、ガスによるブローなどで除去し、その後、当該スラリーを乾燥及び焼成するが、当該焼成は必ずしも行わなくてよい。 First, the particle size of the composite oxide is adjusted to a particle size suitable for the pore diameter of the DPF base material and the roughness of the inner wall surface of the DPF, such as cordierite and SiC. Next, the composite oxide with adjusted particle size is dispersed in a solvent such as pure water to produce a slurry. The slurry is brought into contact with the DPF inner wall using a general method such as impregnation. After the contact, water as a solvent is removed by blowing with gas or the like, and then the slurry is dried and fired. However, the firing is not necessarily performed.
より具体的にはＰＭ触媒１００重量部を水１８００乃至１９００重量部に分散する。分散する際はポリカルボン酸共重合体等の分散剤を１０乃至５０重量部用いてもよい。混合物の粘度は比較的低いので、分散用の容器に、０．３ｍｍのＺｒビーズを７０００乃至８０００重量部程度入れ、ビーズミル分散機で数時間分散すればよい。 More specifically, 100 parts by weight of the PM catalyst is dispersed in 1800 to 1900 parts by weight of water. When dispersing, 10 to 50 parts by weight of a dispersant such as a polycarboxylic acid copolymer may be used. Since the viscosity of the mixture is relatively low, about 7000 to 8000 parts by weight of 0.3 mm Zr beads may be placed in a container for dispersion and dispersed for several hours using a bead mill disperser.
できた分散スラリーは２乃至３質量％に希釈し、ＤＰＦを浸漬させ、余剰スラリーを紙などで吸収し乾燥する。その後更に６００℃程度の温度で熱処理を行い、ＰＭ燃焼用複合酸化物が担持された排ガス浄化用フィルターを得る。代表的には、ＤＰＦ壁面にコーティングする触媒の微粒子の平均粒径を２０〜３００ｎｍ程度とすることで、フルオライト層とペロブスカイト層の結合面がコート表面により露出するようになるため、硫黄含有ガスによる被毒をより抑制できる。 The resulting dispersed slurry is diluted to 2 to 3% by mass, dipped in DPF, and the excess slurry is absorbed with paper or the like and dried. Thereafter, heat treatment is further performed at a temperature of about 600 ° C. to obtain an exhaust gas purification filter carrying a PM combustion composite oxide. Typically, when the average particle size of the catalyst fine particles coated on the DPF wall surface is about 20 to 300 nm, the bonding surface of the fluorite layer and the perovskite layer is exposed by the coating surface. The poisoning due to can be further suppressed.
本発明の排ガス浄化用フィルターが、更に白金族元素を含むことも好ましい構成である。当該白金族元素は、白金（Ｐｔ）、ロジウム（Ｒｈ）又はパラジウム（Ｐｄ）、及びこれらの任意の組み合わせであることが好ましい。 It is also preferable that the exhaust gas purifying filter of the present invention further contains a platinum group element. The platinum group element is preferably platinum (Pt), rhodium (Rh) or palladium (Pd), and any combination thereof.
これは、排ガス中に存在することがある一酸化炭素や炭化水素を除去するために備える。具体的には、排ガス浄化用フィルターの再生やＮＯX吸蔵触媒の再生の際、排気ガス中に燃料を噴射し、燃料を燃焼させる操作を行うことがある。そうした場合、後に添加した燃料に起因して、通常の運転と比較して排気ガス中の一酸化炭素、炭化水素の比率が高くなりやすいことによる。また、浄化触媒成分によりＰＭが燃焼するとき、不完全燃焼により一酸化炭素が発生しやすいことも起こりうる。そこで、より環境に配慮するため、これら一酸化炭素や炭化水素を浄化するべく白金族元素を併用する構成も採用できる。 This is provided to remove carbon monoxide and hydrocarbons that may be present in the exhaust gas. Specifically, when the reproduction of the reproduction and the NO X storage catalyst filter for purifying exhaust gas, the fuel is injected into the exhaust gas, it is possible to perform an operation to burn the fuel. In such a case, due to the fuel added later, the ratio of carbon monoxide and hydrocarbons in the exhaust gas tends to be higher than in normal operation. Further, when PM is burned by the purification catalyst component, carbon monoxide may easily be generated due to incomplete combustion. Therefore, in order to further consider the environment, a configuration in which a platinum group element is used in combination to purify these carbon monoxide and hydrocarbons can also be employed.
白金族元素を用いる場合には、排ガス浄化用フィルターから向かってエンジン側、該フィルター内、該フィルターから向かって大気開放側のどの位置に存在してもよいが、好ましくは排ガス浄化用フィルター内、該フィルターから向かって大気開放側であるのがよい。白金族元素は一酸化炭素や炭化水素といった気体へ作用することが求められるので、高分散状態で担持されていることが好ましい。担持方法は分散状態が担保されていれば特に限定されず、通常よく知られる蒸発乾固、含浸など一般的な方法をいずれも利用できる。 In the case of using a platinum group element, it may be present at any position on the engine side from the exhaust gas purification filter, in the filter, and on the air release side from the filter, preferably in the exhaust gas purification filter, It is good that it is the air release side toward the filter. Since platinum group elements are required to act on gases such as carbon monoxide and hydrocarbons, they are preferably supported in a highly dispersed state. The supporting method is not particularly limited as long as the dispersed state is secured, and any generally known methods such as evaporation to dryness and impregnation which are generally well known can be used.
図３には、排ガス浄化用フィルターの一例を示す。排ガス浄化用フィルター１は入り口側１０から見た断面がハニカム構造をした筒状の形態をしており、材質は多孔質なセラミックで構成されている。図３は、側面から見た断面図である。入り口側（「エンジン側」とも言う。）１０と出口側（「大気開放側」ともいう。）１１は直接的な貫通孔を有しておらず、多孔質セラミックがフィルターとなっている。多孔質セラミックには、具体的には、コージェライト、炭化珪素、チタン酸アルミなどが好適に用いられる。また、フィルター形状は図３に示した構造のほか、発泡体、メッシュ、板状といった形状でもよい。 FIG. 3 shows an example of an exhaust gas purification filter. The exhaust gas purifying filter 1 has a cylindrical shape with a honeycomb structure as viewed from the inlet side 10 and is made of porous ceramic. FIG. 3 is a cross-sectional view seen from the side. The inlet side (also referred to as “engine side”) 10 and the outlet side (also referred to as “atmosphere release side”) 11 do not have direct through holes, and porous ceramics are used as a filter. Specifically, cordierite, silicon carbide, aluminum titanate or the like is preferably used for the porous ceramic. In addition to the structure shown in FIG. 3, the filter shape may be a foam, mesh, or plate shape.
上記排ガス浄化用フィルターにおいて、ＰＭ燃焼用複合酸化物触媒は排ガス流の上流側であるエンジン側１０に配置されるのがよい。これは、本願発明がＰＭ燃焼作用を奏することから、ＰＭが蓄積するエンジン側にないとＰＭ燃焼温度を低下させることができないからである。さらに、上述の理由により白金系の触媒を本発明のＰＭ触媒から大気開放側に配置することもできる。例えば、ＤＰＦのエンジン側の壁面１２に白金系の触媒の層と本発明のＰＭ触媒の層をそれぞれ別々に塗布した多重層構造としてもよい。 In the exhaust gas purification filter, the PM combustion complex oxide catalyst is preferably disposed on the engine side 10 upstream of the exhaust gas flow. This is because the PM combustion temperature cannot be lowered unless the engine is on the engine side where PM accumulates because the present invention exhibits a PM combustion action. Furthermore, for the reasons described above, a platinum-based catalyst can be disposed on the open side from the PM catalyst of the present invention. For example, a multilayer structure in which a platinum-based catalyst layer and a PM catalyst layer of the present invention are separately applied to the wall surface 12 on the engine side of the DPF may be employed.
また、ＰＭ燃焼用複合酸化物触媒をエンジン側の壁面１２に塗布し、大気開放側の壁面１４には白金系触媒の塗料を塗ってもよい。この場合は、エンジン側にＰＭ燃焼用複合酸化物触媒３０があり、大気開放側に白金系の触媒４０が配置されることとなる。また、白金系の触媒粉をＰＭ燃焼用複合酸化物触媒に混ぜて塗布してもよい。なお、白金系の触媒とは、白金族元素を用いた触媒をいう。 Alternatively, the PM combustion composite oxide catalyst may be applied to the engine-side wall surface 12 and the atmosphere-side open wall surface 14 may be coated with a platinum-based catalyst paint. In this case, the PM combustion composite oxide catalyst 30 is provided on the engine side, and the platinum-based catalyst 40 is provided on the atmosphere opening side. Alternatively, platinum-based catalyst powder may be mixed and applied to the PM combustion composite oxide catalyst. The platinum-based catalyst refers to a catalyst using a platinum group element.
本発明のＰＭ燃焼用複合酸化物触媒は、例えば、固相法を用いた製法などによって製造することができる。以下に具体的に説明する。 The composite oxide catalyst for PM combustion of the present invention can be produced, for example, by a production method using a solid phase method. This will be specifically described below.
〔固相法〕
固相法では、まず、所望の複合酸化物を生成するにふさわしい元素を化学量論比で含む原料塩を調製する。原料塩は、硝酸塩、炭酸塩、酸化物、酢酸塩など種々のものがあるが、熱処理により目的とする共存物質の複合酸化物や浄化触媒成分の結晶化を生じるものであれば特に制限はない。混合は、乳鉢などの混合機を用いて行う。
[Solid phase method]
In the solid phase method, first, a raw material salt containing an element suitable for generating a desired composite oxide in a stoichiometric ratio is prepared. There are various raw material salts such as nitrates, carbonates, oxides, and acetates, but there is no particular limitation as long as the heat treatment causes crystallization of the target coexisting complex oxide or purification catalyst component. . Mixing is performed using a mixer such as a mortar.
得られた原料塩を、５００〜１２００℃、好ましくは８００〜１０００℃で２〜３０時間、熱処理することにより、本発明のＰＭ燃焼用複合酸化物触媒を得ることができる。 尚、熱処理時の雰囲気は、複合酸化物を生成できる範囲のものであれば特に制限されず、例えば、空気、窒素、アルゴン、水素、及びそれらに水蒸気を組み合わせた雰囲気が、好ましくは空気、窒素、及びそれらに水蒸気を組み合わせた雰囲気が使用できる。 The composite oxide catalyst for PM combustion of the present invention can be obtained by heat-treating the obtained raw material salt at 500 to 1200 ° C., preferably 800 to 1000 ° C. for 2 to 30 hours. The atmosphere at the time of heat treatment is not particularly limited as long as it is within a range capable of generating a composite oxide. For example, an atmosphere in which air, nitrogen, argon, hydrogen, and water vapor are combined with these is preferably air, nitrogen. , And an atmosphere that combines them with water vapor.
［測定・評価方法］
上述した本発明のＰＭ燃焼用複合酸化物触媒の物性、結晶構造、硫黄に対する耐久性、ＰＭの燃焼性能について実施できる測定・評価方法を説明する。
[Measurement and evaluation method]
A measurement / evaluation method that can be carried out on the physical properties, crystal structure, durability against sulfur, and PM combustion performance of the above-described composite combustion catalyst for PM combustion of the present invention will be described.
＜Ｘ線回折測定＞
前述の通り、本発明のＰＭ燃焼用複合酸化物触媒の構造はＸ線回折により判断することができる。触媒性能を確認するためには少なくとも、アウリビリウス型結晶構造の存在が確認されることが必要である。好ましくは、不純物のメインピークの強度とアウリビリウス型結晶のメインピークの強度比（ｃｐｓ比）がアウリビリウス型／不純物＝２以上であることが好ましい。ここでいうメインピークとは、ＪＣＰＤＳカードチャートに記載されている相対強度がもっとも大きいとされる点での回折線強度をいう。
<X-ray diffraction measurement>
As described above, the structure of the complex oxide catalyst for PM combustion of the present invention can be determined by X-ray diffraction. In order to confirm the catalyst performance, it is necessary to confirm at least the existence of the Aurillius type crystal structure. Preferably, the intensity ratio (cps ratio) of the main peak of the impurity and the main peak of the auribilius crystal is auribius / impurity = 2 or more. The main peak here means the diffraction line intensity at the point where the relative intensity described in the JCPDS card chart is the highest.
例えば、Ｂｉ4Ｔｉ3Ｏ12であれば、２θ＝３５°近傍に現れる回折線がメインピークである。このとき、結晶の成長等の影響で収録されている回折線の位置からわずかにずれることもある。一方、比較対象とされる不純物も同様で、回折線のメインピークは、その回折線の出現形態から同定される物質において、最も相対強度が大きいとされる回折線位置における強度を言う。また、本明細書での構造解析はＸ線回折装置（株式会社リガク製・Ｘ線回折装置ＲＩＮＴ−２１００を用いて測定した。測定条件としては、測定範囲：２θ＝２０〜７０度の範囲、管球：Ｃｏ管球、管電圧：４０ｋＶ・管電流：３０ｍＡとしている。 For example, in the case of Bi 4 Ti 3 O 12 , the diffraction line that appears in the vicinity of 2θ = 35 ° is the main peak. At this time, there may be a slight deviation from the position of the recorded diffraction line due to the effect of crystal growth or the like. On the other hand, the impurities to be compared are the same, and the main peak of the diffraction line refers to the intensity at the diffraction line position where the relative intensity is the highest in the substance identified from the appearance form of the diffraction line. Moreover, the structural analysis in this specification was measured using an X-ray diffractometer (manufactured by Rigaku Corporation / X-ray diffractometer RINT-2100. As measurement conditions, measurement range: 2θ = range of 20 to 70 degrees, Tube: Co tube, tube voltage: 40 kV, tube current: 30 mA.
＜Ｅ１：複合酸化物試料によるＰＭ燃焼温度評価＞
金型プレスを用いて、複合酸化物を１００ｋｇ／ｃｍ2で圧縮成形後、粉砕して、粒子径０．５〜１．０ｍｍの粒状試料を作製する。１ｃｃの当該粒状試料の表面をＣＢが均一に覆うようにローターを使って５分間撹拌する。模擬のＰＭとして、市販のカーボンブラック（ＣＢ）(三菱化学（株）製）を用いる。
<E1: PM combustion temperature evaluation with composite oxide sample>
Using a mold press, the composite oxide is compression molded at 100 kg / cm 2 and then pulverized to produce a granular sample having a particle size of 0.5 to 1.0 mm. Stir for 5 minutes using a rotor so that the CB uniformly covers the surface of the 1 cc granular sample. As the simulated PM, commercially available carbon black (CB) (manufactured by Mitsubishi Chemical Corporation) is used.
得られたＣＢで被覆された粒状試料０．５ｃｃを流通式触媒反応装置を用いて、１０℃／ｍｉｎで８５０℃まで昇温する。雰囲気はＯ2１０％、残部Ｎ2のガスを５００ｃｃ／ｍｉｎの流量で触媒床へ供給し、出口ガスに含まれるＣＯ2を赤外吸収式ガス検出器を用いて定量する。 The obtained CB-coated granular sample (0.5 cc) is heated to 850 ° C. at 10 ° C./min using a flow-type catalytic reactor. The atmosphere is 10% O 2 and the remaining N 2 gas is supplied to the catalyst bed at a flow rate of 500 cc / min, and CO 2 contained in the outlet gas is quantified using an infrared absorption gas detector.
＜硫黄被毒処理材＞
金型プレスを用いて、複合酸化物を１００ｋｇ／ｃｍ2で圧縮成形後、粉砕して、粒子径１．０〜２．０ｍｍの粒状試料を作製する。当該粒状試料３ｇを縦型管状炉に設置し、３００℃×１０時間の処理条件下で、ＳＯ2２００ｐｐｍ、Ｏ2１０％、Ｈ2Ｏ１０％、残部Ｎ2のガスを５００ｃｃ／ｍｉｎの流量で流し、硫黄被毒処理を実施し硫黄被毒処理材を得た。硫黄被毒処理材は、乳鉢にて解粒する。なお、実施例２〜１５はさらに長時間にわたる影響を確認するため、硫黄による被毒処理は５０時間で実施している。
<Sulfur poisoning treatment material>
Using a mold press, the composite oxide is compression molded at 100 kg / cm 2 and then pulverized to prepare a granular sample having a particle size of 1.0 to 2.0 mm. 3 g of the granular sample was placed in a vertical tubular furnace, and under the processing conditions of 300 ° C. × 10 hours, SO 2 200 ppm, O 2 10%, H 2 O 10%, and the balance N 2 gas at a flow rate of 500 cc / min. The sulfur poisoning treatment was carried out to obtain a sulfur poisoning treatment material. The sulfur poisoning treatment material is pulverized in a mortar. In addition, in Examples 2-15, in order to confirm the influence over a long time, the poisoning process by sulfur is implemented in 50 hours.
＜Ｅ２：複合酸化物試料、硫黄被毒処理材によるＰＭ燃焼温度評価＞
模擬のＰＭとして、市販のカーボンブラック（ＣＢ）(三菱化学（株）製）を用い、複合酸化物、硫黄被毒処理の各試料と、カーボンブラックとの、質量比が６：１になるように秤量し、自動乳鉢機（石川工場製ＡＧＡ型）で２０分間混合し、カーボンブラックと各試料の混合粉体を得る。
<E2: PM combustion temperature evaluation with composite oxide sample and sulfur poisoning treatment material>
As a simulated PM, commercially available carbon black (CB) (manufactured by Mitsubishi Chemical Corporation) is used, so that the mass ratio of each sample of composite oxide and sulfur poisoning treatment to carbon black is 6: 1. And mixed with an automatic mortar machine (AGA type manufactured by Ishikawa Factory) for 20 minutes to obtain a mixed powder of carbon black and each sample.
次に、熱重量測定（Ｔｈｅｒｍｏｇｒａｖｉｍｅｔｒｙ：ＴＧ）により、当該各混合粉体における、カーボンブラックの燃焼に伴う質量減少からカーボンブラックの燃焼開始温度を求める。当該ＴＧ測定には、ＴＧ／ＤＴＡ装置（セイコーインスツルメンツ（株）製、ＴＧ／ＤＴＡ６３００型）を用い、混合粉体２０ｍｇを昇温速度１０℃／分にて５０℃から７００℃まで大気中で昇温し、質量測定を行う。カーボンブラックの燃焼温度は、ＤＴＡ（Ｄｉｆｆｅｒｅｎｔｉａｌ Ｔｈｅｒｍａｌ Ａｎａｌｙｓｉｓ）のピーク強度が最大になる点とする。 Next, the combustion start temperature of the carbon black is determined from the mass decrease associated with the combustion of the carbon black in each of the mixed powders by thermogravimetry (TG). For the TG measurement, a TG / DTA apparatus (manufactured by Seiko Instruments Inc., TG / DTA6300 type) is used, and 20 mg of the mixed powder is heated from 50 ° C. to 700 ° C. in the air at a temperature rising rate of 10 ° C./min. Warm and measure mass. The combustion temperature of carbon black is a point at which the peak intensity of DTA (Differential Thermal Analysis) is maximized.
＜Ｅ３：硫黄被毒処理材による吸着硫黄量分析＞
上述した「Ｅ２：複合酸化物試料、硫黄被毒処理材によるＰＭ燃焼温度評価」に調製した硫黄被毒処理材の吸着硫黄量の定量分析を行う。当該定量分析には炭素・硫黄分析装置（（株）ＨＯＲＩＢＡ製ＥＭＩＡ−２２０Ｖ）を用いることができる。
<E3: Adsorption sulfur analysis by sulfur poisoning treatment material>
Quantitative analysis of the amount of adsorbed sulfur of the sulfur poisoning treatment material prepared in “E2: PM combustion temperature evaluation using composite oxide sample and sulfur poisoning treatment material” described above is performed. A carbon / sulfur analyzer (EMIA-220V manufactured by HORIBA) can be used for the quantitative analysis.
（実施例１）
硝酸ビスマス７．９５ｇと酸化チタン２．０５ｇを、メノウ乳鉢を用いて混合した。この場合のビスマス元素とチタン元素のモル比は４：３である。得られた混合物を８００℃で５時間仮焼成し、室温まで自然冷却した。その後、得られた粉体をメノウ乳鉢を用いて、１０分間混合し、９００℃で２時間焼成した。実施例１に係るＰＭ燃焼用複合酸化物触媒のＸ線回折パターンを図１に示す。
Example 1
Bismuth nitrate 7.95 g and titanium oxide 2.05 g were mixed using an agate mortar. In this case, the molar ratio of the bismuth element and the titanium element is 4: 3. The obtained mixture was calcined at 800 ° C. for 5 hours and naturally cooled to room temperature. Thereafter, the obtained powder was mixed for 10 minutes using an agate mortar and baked at 900 ° C. for 2 hours. An X-ray diffraction pattern of the PM combustion composite oxide catalyst according to Example 1 is shown in FIG.
このＸ線回折パターンから上記のようにして作成した物質は、図１に示す回折線を示す。横軸は２θであり、縦軸はカウント数である。また、図１（ｂ）は図１（ａ）の２θが２０°から４０°までを拡大した図である。また、図１（ａ）で白丸はＢｉ4Ｔｉ3Ｏ12のピークを表わし、黒丸はＢｉ12ＴｉＯ20のピークを表わす。 The material prepared as described above from this X-ray diffraction pattern exhibits the diffraction lines shown in FIG. The horizontal axis is 2θ, and the vertical axis is the count number. FIG. 1B is an enlarged view of 2θ in FIG. 1A from 20 ° to 40 °. In FIG. 1A, the white circles represent the Bi 4 Ti 3 O 12 peak, and the black circles represent the Bi 12 TiO 20 peak.
これより、主構成物質はＢｉ4Ｔｉ3Ｏ12の結晶構造を有すると同定された。このことからＢｉ2Ａn-1ＢnＯ3n+3におけるＡ：Ｂｉ、Ｂ：Ｔｉであってｎ＝３となり、フルオライト層がＢｉ2Ｏ2、ペロブスカイト層がＢｉ2Ｔｉ3Ｏ10で構成されていると判断できる。さらに、不純物は同じく回折線の形態より、Ｂｉ12ＴｉＯ20と同定された。 Thus, the main constituent material was identified as having a crystal structure of Bi 4 Ti 3 O 12 . Therefore, A: Bi and B: Ti in Bi 2 A n-1 B n O 3n + 3 are n = 3, the fluorite layer is Bi 2 O 2 , and the perovskite layer is Bi 2 Ti 3 O 10 . It can be judged that it is configured. Furthermore, the impurity was also identified as Bi 12 TiO 20 from the form of diffraction lines.
ここで図１（ｂ）を参照して、アウリビリウス型結晶であるＢｉ4Ｔｉ3Ｏ12の回折線の最強線はおおよそ２θ＝３５°近傍に現れる（ＪＣＰＤＳカード；３５−０７９５（斜方晶系））ので、最強線としてはこれを採用した。本例における強度は２θ＝３５．２４°で４０９６ｃｐｓを示した。また、不純物Ｂｉ12ＴｉＯ20の回折線の最強線はおおよそ２θ＝３２°近傍に現れる（ＪＣＰＤＳカード；４２−０１８６）ので、最強線としてはこれを採用する。本例における強度は２θ＝３２．２８°で６９０ｃｐｓを示した。したがって、アウリビリウス型結晶／不純物＝５．９４である。 Here, referring to FIG. 1 (b), the strongest line of diffraction lines of Bi 4 Ti 3 O 12 which is an Aurivirius crystal appears in the vicinity of 2θ = 35 ° (JCPDS card; 35-0795 (orthorhombic system) )) So we adopted this as the strongest line. The intensity in this example was 4096 cps at 2θ = 35.24 °. Further, the strongest line of the diffraction line of impurity Bi 12 TiO 20 appears in the vicinity of 2θ = 32 ° (JCPDS card; 42-0186), and this is adopted as the strongest line. The intensity in this example was 690 cps at 2θ = 32.28 °. Therefore, auribilius type crystal / impurity = 5.94.
（実施例２）
硝酸ビスマスを酸化ビスマスに変更し、添加量として酸化ビスマスは４．７８ｇ、酸化チタンは１．３１ｇとした以外は実施例１と同様にして、本例のＰＭ燃焼用複合酸化物触媒を得た。
(Example 2)
The PM combustion composite oxide catalyst of this example was obtained in the same manner as in Example 1 except that bismuth nitrate was changed to bismuth oxide and the addition amount was 4.78 g bismuth oxide and 1.31 g titanium oxide. .
（実施例３〜１５）
ペロブスカイト層を形成する元素の一部をＬａ、Ｂａ、Ｃａ、Ｓｒ、Ｆｅに各々置換した以外は実施例２と同様にして、各例のＰＭ燃焼用複合酸化物触媒を形成させた。置換量と構成比は表１にあわせて示す。なお、表１において、実施例１については、材料として硝酸ビスマスを用いており、「※」でそれを示した。
(Examples 3 to 15)
The composite oxide catalyst for PM combustion in each example was formed in the same manner as in Example 2 except that part of the elements forming the perovskite layer was replaced with La, Ba, Ca, Sr, and Fe. The amount of substitution and the composition ratio are shown in Table 1. In Table 1, for Example 1, bismuth nitrate was used as a material, which is indicated by “*”.
（比較例１）
硝酸セリウムの０．２ｍｏｌ／Ｌの試料溶液を調製した。この水溶液を撹拌しながら水溶液の温度を２５℃に調整し、温度が２５℃に達した段階で、沈殿剤として炭酸アンモニウムを添加しｐＨ＝８として、沈殿を生成させた。得られた沈殿物を濾過して回収した後、水洗し、１２５℃で乾燥し前駆体粉を得た。次に、当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例１に係る酸化セリウム（ＣｅＯ2）を得た。この酸化セリウムはフルオライト構造を有していた。
(Comparative Example 1)
A 0.2 mol / L sample solution of cerium nitrate was prepared. While stirring this aqueous solution, the temperature of the aqueous solution was adjusted to 25 ° C., and when the temperature reached 25 ° C., ammonium carbonate was added as a precipitating agent to adjust the pH to 8 to produce a precipitate. The obtained precipitate was collected by filtration, washed with water, and dried at 125 ° C. to obtain a precursor powder. Next, the precursor powder was heat treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain cerium oxide (CeO 2 ) according to Comparative Example 1. This cerium oxide had a fluorite structure.
（比較例２）
硝酸ランタン、硝酸バリウム及び硝酸鉄をランタン元素とバリウム元素と鉄元素のモル比が０．８：０．２：１．０になるように秤量し、１９４８．３ｇの純水に溶解させることで、０．２ｍｏｌ／Ｌ料溶液を調製した。この水溶液にＮ2をバブリングしながら、槽内の酸素濃度が０％になるまで撹拌した。その後、水溶液の温度を３０℃に調整し、温度が３０℃に達した段階で、沈殿剤として濃度が２１．５７質量％のアンモニア水を８２１．１ｇ添加した。
(Comparative Example 2)
By weighing lanthanum nitrate, barium nitrate and iron nitrate so that the molar ratio of lanthanum element, barium element and iron element is 0.8: 0.2: 1.0, and dissolving in 1948.3 g of pure water. A 0.2 mol / L material solution was prepared. While bubbling N 2 through this aqueous solution, the solution was stirred until the oxygen concentration in the tank reached 0%. Thereafter, the temperature of the aqueous solution was adjusted to 30 ° C., and when the temperature reached 30 ° C., 821.1 g of ammonia water having a concentration of 21.57% by mass was added as a precipitant.
その後、１００％のＣＯ2ガスを２．５２Ｌ／ｍｉｎのガス流速で反応槽の下部より１６分間バブリングした。得られた沈殿物を濾過して回収した後、水洗し、１２５℃で乾燥し前駆体粉を得た。次に、当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例２に係るペロブスカイト酸化物（Ｌａ0.8Ｂａ0.2ＦｅＯ3）を得た。このペロブスカイト酸化物はフルオライト層を有していなかった。 Thereafter, 100% CO 2 gas was bubbled from the bottom of the reaction vessel for 16 minutes at a gas flow rate of 2.52 L / min. The obtained precipitate was collected by filtration, washed with water, and dried at 125 ° C. to obtain a precursor powder. Next, the precursor powder was heat-treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain a perovskite oxide (La 0.8 Ba 0.2 FeO 3 ) according to Comparative Example 2. This perovskite oxide did not have a fluorite layer.
（比較例３）
硝酸ランタン及び硝酸鉄をランタン元素と鉄元素のモル比が１．０：１．０になるように秤量し、１９４８．３ｇの純水に溶解させることで、０．２ｍｏｌ／Ｌ料溶液を調製した。この水溶液にＮ2をバブリングしながら、槽内の酸素濃度が０％になるまで撹拌した。その後、水溶液の温度を３０℃に調整し、温度が３０℃に達した段階で、沈殿剤として濃度が２１．５７質量％のアンモニア水を８２１．１ｇ添加した。
(Comparative Example 3)
A 0.2 mol / L material solution is prepared by weighing lanthanum nitrate and iron nitrate so that the molar ratio of lanthanum element to iron element is 1.0: 1.0 and dissolving in 1948.3 g of pure water. did. While bubbling N 2 through this aqueous solution, the solution was stirred until the oxygen concentration in the tank reached 0%. Thereafter, the temperature of the aqueous solution was adjusted to 30 ° C., and when the temperature reached 30 ° C., 821.1 g of ammonia water having a concentration of 21.57% by mass was added as a precipitant.
その後、１００％のＣＯ2ガスを２．５２Ｌ／ｍｉｎのガス流速で反応槽の下部より１６分間バブリングした。得られた沈殿物を濾過して回収した後、水洗し、１２５℃で乾燥し前駆体粉を得た。次に、当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例３に係るペロブスカイト酸化物（Ｌａ0.6Ｓｒ0.4ＦｅＯ3）を得た。このペロブスカイト酸化物もフルオライト層を有していなかった。 Thereafter, 100% CO 2 gas was bubbled from the bottom of the reaction vessel for 16 minutes at a gas flow rate of 2.52 L / min. The obtained precipitate was collected by filtration, washed with water, and dried at 125 ° C. to obtain a precursor powder. Next, the precursor powder was heat-treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain a perovskite oxide (La 0.6 Sr 0.4 FeO 3 ) according to Comparative Example 3. This perovskite oxide also did not have a fluorite layer.
（比較例４）
市販のγアルミナ（比表面積２５０ｍ2／ｇ）（ＳＡＳＯＬ社製ＰＵＲＡＬＯＸ ＳＣＦａ１４０）３０ｇを、濃度８．５質量％ジニトロジアンミン白金水溶液（田中貴金属工業（株）社製）３．６ｇと純水２８５ｇとを混合したジニトロジアンミン白金水溶液へ、２５℃にて１５時間浸漬し、γアルミナにＰｔを含浸させた。当該γアルミナを回収した後、９０℃で１２時間、通風乾燥を行い、更に大気雰囲気下で５００℃、１時間熱処理して比較例４に係るＰｔ含有量１.０質量％のＰｔ担持アルミナ（１質量％Ｐｔ／Ａｌ2Ｏ3）を得た。このＰｔ担持アルミナはペロブスカイトでもフルオライトでもアウリビリウスでもなかった。
(Comparative Example 4)
30 g of commercially available γ-alumina (specific surface area 250 m 2 / g) (PURALOX SCFa140 manufactured by SASOL), 3.6 g of dinitrodiammine platinum aqueous solution (produced by Tanaka Kikinzoku Kogyo Co., Ltd.) and 285 g of pure water Was immersed in an aqueous solution of dinitrodiammine platinum mixed at 25 ° C. for 15 hours to impregnate γ-alumina with Pt. After collecting the γ-alumina, it was air-dried at 90 ° C. for 12 hours, and further heat-treated at 500 ° C. for 1 hour in an air atmosphere, and Pt-supported alumina having a Pt content of 1.0 mass% according to Comparative Example 4 ( 1 mass% Pt / Al 2 O 3 ) was obtained. This Pt-supported alumina was neither perovskite, fluorite nor aurivirius.
（比較例５）
セリウム元素とジルコニウム元素が０．１６：０．８３である市販のセリアジルコニア複合酸化物を空気中８００℃で２時間焼成し、比較例５に係る触媒を得た。
(Comparative Example 5)
A commercially available ceria zirconia composite oxide having a cerium element and a zirconium element of 0.16: 0.83 was calcined in air at 800 ° C. for 2 hours to obtain a catalyst according to Comparative Example 5.
（比較例６）
酸化ネオジムを濃硝酸溶液に溶解させ、１９．２質量％のネオジム水溶液を調製した。得られたネオジム水溶液と硝酸鉄をネオジム元素と鉄元素がモル比で１：１になるように秤量し、６１７．４ｇの純水に溶解させることで、０．２ｍｏｌ／Ｌの試料溶液を調製した。この溶液を撹拌しながら、沈殿材として濃度が２３．０２質量％のアンモニア水を６５．１ｇ添加した。その後、１００％のＣＯ2ガスを０．３３Ｌ／ｍｉｎのガス流速で反応槽の下部より２０ｍｉｎバブリングした。得られた沈殿物を濾過して回収した後、水洗し、１１０℃で乾燥し前駆体粉を得た。次に当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例６に係るペロブスカイト酸化物（ＮｄＦｅＯ3）を得た。このペロブスカイト酸化物もフルオライト層を有していなかった。
(Comparative Example 6)
Neodymium oxide was dissolved in a concentrated nitric acid solution to prepare a 19.2 mass% neodymium aqueous solution. The obtained neodymium aqueous solution and iron nitrate are weighed so that the molar ratio of neodymium element and iron element is 1: 1, and dissolved in 617.4 g of pure water to prepare a 0.2 mol / L sample solution. did. While stirring this solution, 65.1 g of ammonia water having a concentration of 23.02% by mass as a precipitation material was added. Thereafter, 100% CO 2 gas was bubbled from the bottom of the reaction vessel for 20 min at a gas flow rate of 0.33 L / min. The obtained precipitate was collected by filtration, washed with water, and dried at 110 ° C. to obtain a precursor powder. Next, the precursor powder was heat-treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain a perovskite oxide (NdFeO 3 ) according to Comparative Example 6. This perovskite oxide also did not have a fluorite layer.
（比較例７）
酸化ガドリニウムを濃硝酸溶液に溶解させ、１９．８質量％のガドリニウム水溶液を調製した。得られたガドリニウム水溶液と硝酸鉄をガドリニウム元素と鉄元素がモル比で１：１になるように秤量し、６１３．５ｇの純水に溶解させることで、０．２ｍｏｌ／Ｌの試料溶液を調製した。この溶液を撹拌しながら、沈殿材として濃度が２３．０２質量％のアンモニア水を６５．１ｇ添加した。その後、１００％のＣＯ2ガスを０．３３Ｌ／ｍｉｎのガス流速で反応槽の下部より２０ｍｉｎバブリングした。得られた沈殿物を濾過して回収した後、水洗し、１１０℃で乾燥し前駆体粉を得た。次に当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例７に係るペロブスカイト酸化物（ＧｄＦｅＯ3）を得た。このペロブスカイト酸化物もフルオライト層を有していなかった。
(Comparative Example 7)
Gadolinium oxide was dissolved in a concentrated nitric acid solution to prepare a 19.8% by mass gadolinium aqueous solution. The obtained gadolinium aqueous solution and iron nitrate are weighed so that the gadolinium element and iron element have a molar ratio of 1: 1, and dissolved in 613.5 g of pure water to prepare a 0.2 mol / L sample solution. did. While stirring this solution, 65.1 g of ammonia water having a concentration of 23.02% by mass as a precipitation material was added. Thereafter, 100% CO 2 gas was bubbled from the bottom of the reaction vessel for 20 min at a gas flow rate of 0.33 L / min. The obtained precipitate was collected by filtration, washed with water, and dried at 110 ° C. to obtain a precursor powder. Next, the precursor powder was heat-treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain a perovskite oxide (GdFeO 3 ) according to Comparative Example 7. This perovskite oxide also did not have a fluorite layer.
（比較例８）
硝酸ランタンと硝酸バリウムと硝酸マンガンをランタン元素とバリウム元素とマンガン元素がモル比で０．６：０．４：１．０になるように秤量し、２９４８．３ｇの純水に溶解させることで、０．２ｍｏｌ／Ｌの試料溶液を調製した。この溶液を撹拌しながら、沈殿材として濃度が２３．３４質量％のアンモニア水を３０９．４ｇ添加した。その後、１００％のＣＯ2ガスを１．６８Ｌ／ｍｉｎのガス流速で反応槽の下部より２２ｍｉｎバブリングした。得られた沈殿物を濾過して回収した後、水洗し、１２５℃で乾燥し前駆体粉を得た。次に当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例８に係るペロブスカイト酸化物（Ｌａ0.6Ｂａ0.4ＭｎＯ3）を得た。このペロブスカイト酸化物もフルオライト層を有していなかった。
(Comparative Example 8)
By weighing lanthanum nitrate, barium nitrate and manganese nitrate so that the molar ratio of lanthanum element, barium element and manganese element is 0.6: 0.4: 1.0, and dissolving them in 2948.3 g of pure water. A sample solution of 0.2 mol / L was prepared. While stirring this solution, 309.4 g of ammonia water having a concentration of 23.34% by mass was added as a precipitation material. Thereafter, 100% CO 2 gas was bubbled from the bottom of the reaction vessel for 22 min at a gas flow rate of 1.68 L / min. The obtained precipitate was collected by filtration, washed with water, and dried at 125 ° C. to obtain a precursor powder. Next, the precursor powder was heat-treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain a perovskite oxide (La 0.6 Ba 0.4 MnO 3 ) according to Comparative Example 8. This perovskite oxide also did not have a fluorite layer.
（比較例９）
硝酸ランタンと硝酸ストロンチウムと硝酸マンガンをランタン元素とストロンチウム元素とマンガン元素がモル比で０．８：０．２：１．０になるように秤量し、２９４８．３ｇの純水に溶解させることで、０．２ｍｏｌ／Ｌの試料溶液を調製した。この溶液を撹拌しながら、沈殿材として濃度が２３．３４質量％のアンモニア水を３０９．４ｇ添加した。その後、１００％のＣＯ2ガスを１．６８Ｌ／ｍｉｎのガス流速で反応槽の下部より２２ｍｉｎバブリングした。得られた沈殿物を濾過して回収した後、水洗し、１２５℃で乾燥し前駆体粉を得た。次に当該前駆体粉を、大気雰囲気下において８００℃で２時間熱処理して焼成し、比較例９に係るペロブスカイト酸化物（Ｌａ0.8Ｓｒ0.2ＭｎＯ3）を得た。このペロブスカイト酸化物もフルオライト層を有していなかった。
(Comparative Example 9)
By weighing lanthanum nitrate, strontium nitrate and manganese nitrate so that the molar ratio of lanthanum element, strontium element and manganese element is 0.8: 0.2: 1.0, and dissolving in 2948.3 g of pure water. A sample solution of 0.2 mol / L was prepared. While stirring this solution, 309.4 g of ammonia water having a concentration of 23.34% by mass was added as a precipitation material. Thereafter, 100% CO 2 gas was bubbled from the bottom of the reaction vessel for 22 min at a gas flow rate of 1.68 L / min. The obtained precipitate was collected by filtration, washed with water, and dried at 125 ° C. to obtain a precursor powder. Next, the precursor powder was heat-treated at 800 ° C. for 2 hours in an air atmosphere and fired to obtain a perovskite oxide (La 0.8 Sr 0.2 MnO 3 ) according to Comparative Example 9. This perovskite oxide also did not have a fluorite layer.
（比較例１０）
硝酸ストロンチウムとオキシ硝酸ジルコニウムを、ストロンチウム元素とジルコニウム元素が０．８５：１．１５になるように混合し、乳鉢を用いて混合した。得られた混合物を８００℃で５時間仮焼成し、ＳｒＺｒＯ3を得た。得られたＳｒＺｒＯ3はペロブスカイト構造を有していた。比較例１に係る酸化セリウムに対して当該ＳｒＺｒＯ3を２０質量％混合することで、比較例１０に係る混合粉を得た。
(Comparative Example 10)
Strontium nitrate and zirconium oxynitrate were mixed so that the elements of strontium and zirconium were 0.85: 1.15 and mixed using a mortar. The obtained mixture was calcined at 800 ° C. for 5 hours to obtain SrZrO 3 . The obtained SrZrO 3 had a perovskite structure. The mixed powder according to Comparative Example 10 was obtained by mixing 20% by mass of the SrZrO 3 with the cerium oxide according to Comparative Example 1.
（評価）
図２に＜Ｅ１：複合酸化物試料によるＰＭ燃焼温度評価＞の結果を示す。図２において、縦軸は出口でのＣＯ2濃度を示し、横軸はサンプルの温度を示す。ＣＯ2濃度が上昇したということは、内部でＰＭが燃焼したことを示している。図２より、実施例１と比較例１、２及び４のＣＯ2発生の温度域を比較すると、実施例１（図中黒丸印）のほうが低温からＣＯ2の発生が認められる。
(Evaluation)
FIG. 2 shows the results of <E1: PM combustion temperature evaluation using composite oxide sample>. In FIG. 2, the vertical axis indicates the CO 2 concentration at the outlet, and the horizontal axis indicates the temperature of the sample. The increase in the CO 2 concentration indicates that PM has burned inside. From FIG. 2, when comparing the temperature range of CO 2 generation in Comparative Examples 1, 2 and 4 of Example 1, towards the Example 1 (drawing black circles) was observed the generation of CO 2 from a low temperature.
これより本発明のＰＭ燃焼用複合酸化物触媒はＰＭの燃焼温度を下げる触媒活性が比較例と比べて高いといえる。ペロブスカイト構造の酸素供給能力は、実施例１のＢｉとＴｉの組み合わせに対して、比較例２のＬａ、Ｂａ、Ｆｅといった元素の組み合わせで大きく変化はしない。従って、実施例１及び比較例との違いは、フルオライト層が存在してアウリビリウス構造になっているか否かであることから、フロオライト層とペロブスカイト層から構成される層状構造酸化物を用いればＰＭの燃焼温度を低くできることがわかる。 From this, it can be said that the composite oxide catalyst for PM combustion of the present invention has a higher catalytic activity for lowering the combustion temperature of PM than the comparative example. The oxygen supply capacity of the perovskite structure is not greatly changed by the combination of elements such as La, Ba, and Fe of Comparative Example 2 with respect to the combination of Bi and Ti of Example 1. Therefore, the difference between Example 1 and the comparative example is whether or not a fluorite layer exists and has an auribilius structure. Therefore, if a layered structure oxide composed of a fluorite layer and a perovskite layer is used, PM It can be seen that the combustion temperature of can be lowered.
また、実施例１と比較例４のＣＯ2発生の温度域を比較すると、実施例１のほうが低温からＣＯ2の発生が認められることから、本発明に係る排気ガス浄化材は、Ｐｔ等の貴金属を含有することなくそれ自体でＰＭを低温で燃焼させることができることがわかる。 Further, when comparing the temperature range of CO 2 generation between Example 1 and Comparative Example 4, since CO 2 is generated from Example 1 at a lower temperature, the exhaust gas purifying material according to the present invention is made of Pt or the like. It can be seen that PM itself can be burned at low temperatures without containing noble metals.
次に＜Ｅ２：複合酸化物試料、硫黄被毒処理材によるＰＭ燃焼温度評価＞と＜Ｅ３：硫黄被毒処理材による吸着硫黄量分析＞の結果を表２および表３に示す。Ｅ２による評価は「ＰＭ燃焼温度」に結果を示し、Ｅ３による評価結果は「吸着硫黄量」を示す。 Next, Tables 2 and 3 show the results of <E2: PM combustion temperature evaluation by composite oxide sample and sulfur poisoning treatment material> and <E3: Adsorption sulfur amount analysis by sulfur poisoning treatment material>. The evaluation by E2 shows the result in “PM combustion temperature”, and the evaluation result by E3 shows “adsorption sulfur amount”.
表２および３より、実施例１では、比較例１、２及び８〜１０に比べ、硫黄被毒前のＰＭ燃焼温度は高いものの、硫黄被毒前のＰＭ燃焼温度と硫黄被毒後のＰＭ燃焼温度の差Δ
Ｔが小さく、吸着硫黄量も少ないことから、アウリビリウス型結晶構造酸化物であるほうが、硫黄被毒による触媒活性の低下を回避できることがわかる。
From Tables 2 and 3, in Example 1, although the PM combustion temperature before sulfur poisoning is higher than in Comparative Examples 1, 2, and 8 to 10, PM combustion temperature before sulfur poisoning and PM after sulfur poisoning Difference in combustion temperature Δ
Since T is small and the amount of adsorbed sulfur is small, it can be seen that a reduction in catalytic activity due to sulfur poisoning can be avoided in the case of an Aurivirius crystal structure oxide.
更に、実施例１と比較例４の硫黄被毒前後のＰＭ燃焼温度を比べると、実施例１のほうが、硫黄被毒前及び硫黄被毒後共にＣＢ燃焼温度が低いことから、本発明に係る排気ガス浄化材は、Ｐｔ等の貴金属触媒よりも高い活性を有することがわかる。 Furthermore, when comparing the PM combustion temperatures before and after sulfur poisoning in Example 1 and Comparative Example 4, Example 1 has a lower CB combustion temperature both before and after sulfur poisoning. It can be seen that the exhaust gas purification material has a higher activity than a noble metal catalyst such as Pt.
以上のことより、ペロブスカイト型格子を構成単位として含む層状構造酸化物を担持したフィルターを用いれば、Ｐｔ等の貴金属を含有することなくＰＭを低温で燃焼させることができ、かつ、ディーゼルエンジン排気ガス中に含まれる硫黄によるＰＭ燃焼活性の低下が抑制され、ＰＭ燃焼活性を維持できる。 From the above, if a filter carrying a layered structure oxide containing a perovskite lattice as a constituent unit is used, PM can be burned at low temperatures without containing noble metals such as Pt, and diesel engine exhaust gas A decrease in PM combustion activity due to sulfur contained therein is suppressed, and PM combustion activity can be maintained.
１ 排ガス浄化用フィルター
１０ 入り口側、エンジン側
１１ 出口側、大気開放側
１２ エンジン側の壁面
１４ 大気開放側の壁面
３０ ＰＭ燃焼用複合酸化物触媒
４０ 白金系の触媒
５０ Ｂｉ元素
５１ 酸素元素
５２ ＢＯ6八面体格子
１００ フルオライト層
１１０ ペロブスカイト層
DESCRIPTION OF SYMBOLS 1 Exhaust gas purification filter 10 Inlet side, engine side 11 Outlet side, atmosphere release side 12 Engine side wall 14 Atmosphere release side wall 30 PM combustion complex oxide catalyst 40 Platinum-based catalyst 50 Bi element 51 Oxygen element 52 BO 6 octahedral lattice 100 fluorite layer 110 perovskite layer
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| JP2013120908A (en) * | 2011-12-08 | 2013-06-17 | Seiko Epson Corp | Method for manufacturing liquid injection head, method for manufacturing liquid injection apparatus, and method for manufacturing piezoelectric element |
| JP2014152052A (en) * | 2013-02-06 | 2014-08-25 | National Institute For Materials Science | Perovskite nanosheet based on homologous laminar perovskite oxide and its use |
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| JP2013120908A (en) * | 2011-12-08 | 2013-06-17 | Seiko Epson Corp | Method for manufacturing liquid injection head, method for manufacturing liquid injection apparatus, and method for manufacturing piezoelectric element |
| JP2014152052A (en) * | 2013-02-06 | 2014-08-25 | National Institute For Materials Science | Perovskite nanosheet based on homologous laminar perovskite oxide and its use |
| CN106560242A (en) * | 2015-10-01 | 2017-04-12 | 清洁柴油技术有限公司 | Effect Of Type Of Support Oxide On Sulfur Resistance Of Synergized Pgm As Diesel Oxidation Catalyst |
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