JPH06304449A - Apparatus for removing nitrogen oxide - Google Patents
Apparatus for removing nitrogen oxideInfo
- Publication number
- JPH06304449A JPH06304449A JP5120520A JP12052093A JPH06304449A JP H06304449 A JPH06304449 A JP H06304449A JP 5120520 A JP5120520 A JP 5120520A JP 12052093 A JP12052093 A JP 12052093A JP H06304449 A JPH06304449 A JP H06304449A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- catalyst layer
- platinum
- perovskite structure
- nitrogen oxide
- 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.)
- Pending
Links
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 169
- 239000003054 catalyst Substances 0.000 claims abstract description 125
- 239000007789 gas Substances 0.000 claims abstract description 40
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 30
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 24
- 239000000126 substance Substances 0.000 claims abstract description 17
- 229910052712 strontium Inorganic materials 0.000 claims abstract description 6
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 5
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 5
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 4
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 4
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 58
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 44
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 239000011575 calcium Substances 0.000 claims description 6
- 229910052684 Cerium Inorganic materials 0.000 claims description 5
- 229910052788 barium Inorganic materials 0.000 claims description 5
- 239000011651 chromium Substances 0.000 claims description 5
- 239000011777 magnesium Substances 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 3
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 3
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 3
- 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 claims description 2
- 229910052748 manganese Inorganic materials 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract 2
- 229910052757 nitrogen Inorganic materials 0.000 abstract 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 54
- 230000000694 effects Effects 0.000 description 19
- 238000000034 method Methods 0.000 description 19
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 17
- 238000000354 decomposition reaction Methods 0.000 description 16
- 239000000843 powder Substances 0.000 description 16
- 229910052751 metal Inorganic materials 0.000 description 15
- 238000001179 sorption measurement Methods 0.000 description 13
- 239000013078 crystal Substances 0.000 description 12
- 239000002184 metal Substances 0.000 description 12
- 239000008188 pellet Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 229910002651 NO3 Inorganic materials 0.000 description 9
- 230000007547 defect Effects 0.000 description 9
- 150000003839 salts Chemical class 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- 238000000746 purification Methods 0.000 description 8
- 239000007864 aqueous solution Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 238000002485 combustion reaction Methods 0.000 description 6
- 229910017604 nitric acid Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 230000009471 action Effects 0.000 description 5
- 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 5
- 238000001354 calcination Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 230000004913 activation Effects 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 229910052878 cordierite Inorganic materials 0.000 description 3
- 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 3
- 238000009434 installation Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000000567 combustion gas Substances 0.000 description 2
- 230000009918 complex formation Effects 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 150000002823 nitrates Chemical class 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229910000873 Beta-alumina solid electrolyte Inorganic materials 0.000 description 1
- 229910002492 Ce(NO3)3·6H2O Inorganic materials 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 229910020851 La(NO3)3.6H2O Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 159000000021 acetate salts Chemical class 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 229940011182 cobalt acetate Drugs 0.000 description 1
- 229910000428 cobalt oxide Inorganic materials 0.000 description 1
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 1
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 1
- KVRXQOCZXUAPSN-UHFFFAOYSA-N cobalt;oxosilver Chemical compound [Co].[Ag]=O KVRXQOCZXUAPSN-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000011491 glass wool Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 150000004698 iron complex Chemical class 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
- 238000011068 loading method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 150000002910 rare earth metals Chemical group 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、内燃機関や硝酸製造工
場等から排出される気体中に含まれる窒素酸化物（ＮＯ
x ）を除去するための装置に関するものである。BACKGROUND OF THE INVENTION The present invention relates to nitrogen oxides (NO) contained in gas discharged from internal combustion engines, nitric acid manufacturing plants, etc.
x ) for removing the device.
【０００２】[0002]
【従来の技術】内燃機関や硝酸製造工場等から排出され
る気体中には窒素酸化物が含まれており、大気汚染の原
因となっている。この窒素酸化物を除去する方法とし
て、触媒の還元反応を利用する方法がある。2. Description of the Related Art Nitrogen oxides are contained in the gas discharged from an internal combustion engine, a nitric acid manufacturing plant, etc., which causes air pollution. As a method of removing this nitrogen oxide, there is a method of utilizing a reduction reaction of a catalyst.
【０００３】従来の触媒を利用した窒素酸化物の除去方
法としては、（Ａ）β−アルミナにＫ、Ｎａ、Ｃａ、Ｂ
ａ、Ｌａ、Ｃｅ、Ｐｒ等を担持した触媒を利用する方法
（特開平４−２９８２３５号）、（Ｂ）マグネタイト
（Ｆｅ2 Ｏ4 ）を還元処理して酸素欠陥を生じさせた活
性化マグネタイトよりなる触媒を利用する方法（特開平
３−２４２２２８号）、あるいは（Ｃ）白金アルミナ、
銀コバルト酸化物、コバルト酸化物、またはバリウム−
鉄複合酸化物等の金属酸化物系の触媒を利用して窒素酸
化物を分解する方法（「触媒」３１、１１２（１９８
９））がある。As a conventional method for removing nitrogen oxides using a catalyst, (A) β-alumina is mixed with K, Na, Ca and B.
a method using a catalyst carrying a, La, Ce, Pr, etc. (JP-A-4-298235), (B) magnetite (Fe 2 O 4 ) reduction treatment from activated magnetite in which oxygen defects are generated Using a catalyst (JP-A-3-242228), or (C) platinum alumina,
Silver cobalt oxide, cobalt oxide, or barium-
A method for decomposing nitrogen oxides using a metal oxide-based catalyst such as iron complex oxide (“Catalyst” 31 , 112 (198).
9)).
【０００４】しかし、上記の触媒を利用した方法では、
以下のような問題点がある。However, in the method utilizing the above catalyst,
There are the following problems.
【０００５】まず、（Ａ）の方法では、窒素酸化物を還
元するための炭化水素やアルコール類等の還元剤を多量
に使用する必要がある（窒素酸化物１モルに対して還元
剤０．１〜２モル必要である）。First, in the method (A), it is necessary to use a large amount of a reducing agent such as hydrocarbons or alcohols for reducing nitrogen oxides (0. 1-2 mol is required).
【０００６】また、（Ｂ）の方法では、活性マグネタイ
トの酸素欠陥部を使用し終わると該活性マグネタイトが
失活するため、持続性に欠ける。Further, in the method (B), since the active magnetite is deactivated after the oxygen defect portion of the active magnetite is used, the durability is lacking.
【０００７】また、（Ｃ）の方法では、窒素酸化物の分
解には６００℃以上の高温を必要とする。In the method (C), decomposition of nitrogen oxides requires a high temperature of 600 ° C. or higher.
【０００８】さらに、上記のような問題のない方法であ
り、窒素酸化物の除去方法に類似のものとして、２種類
の触媒体を連設した燃焼器がある（特開昭６２−２１８
７２８号）。この燃焼器は、燃焼ガスの流路の前段に白
金担持の触媒体を配置し、その後段に白金とアルミナと
希土類金属とがペロブスカイト型構造を形成した触媒体
を配置したガスタービン燃焼器である。この燃焼器で
は、燃料と酸化性気体との混合物からなる燃焼ガスの燃
焼温度を上記２種類の触媒によりひき下げること（２０
００℃を９００〜１２００℃にする）により窒素酸化物
の発生を減少させるものである。Further, there is a combustor in which two kinds of catalysts are connected in series as a method which does not have the above-mentioned problems and is similar to the method for removing nitrogen oxides (Japanese Patent Laid-Open No. 62-218).
728). This combustor is a gas turbine combustor in which a platinum-supported catalyst body is arranged in the preceding stage of a combustion gas flow path, and a catalyst body in which platinum, alumina, and a rare earth metal form a perovskite structure is arranged in the latter stage. . In this combustor, the combustion temperature of the combustion gas composed of a mixture of fuel and oxidizing gas is lowered by the above two types of catalysts (20
The generation of nitrogen oxides is reduced by setting the temperature of 00 ° C. to 900 to 1200 ° C.).
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、上記の
燃焼器でも以下のような問題点が残っている。However, the above-mentioned combustor also has the following problems.
【００１０】ＮＯx の主成分であるＮＯのＮ−Ｏ間
（２．５重結合）の結合エネルギが極めて大きいため、
この結合を切断するのは容易ではない。気相均一系にお
いてＮＯを分解する活性化エネルギは８２ｋｃａｌ／ｍ
ｏｌと大きいため、気相温度を上げる等の手段によりエ
ネルギを加えないとＮＯ分解は起きない。後段の触媒体
では、この分解活性が低く、しかも吸着能力が小さいた
め、特に５００℃以下のような低温における窒素酸化物
の除去効率が低い。これは、後段のペロブスカイト型構
造の触媒には、アルミナ含有等により格子欠陥の状態や
活性種である白金や希土類元素等の結晶構造における間
隔等が適正ではないためである。Since NO, which is the main component of NO x , has a very large binding energy between N and O (2.5 double bonds),
It is not easy to break this bond. Activation energy for decomposing NO in a gas phase homogeneous system is 82 kcal / m
Since it is as large as ol, NO decomposition does not occur unless energy is added by means such as raising the gas phase temperature. In the latter stage catalyst body, this decomposition activity is low and the adsorption ability is small, so that the removal efficiency of nitrogen oxides is low especially at a low temperature of 500 ° C. or lower. This is because the catalyst having a perovskite structure in the latter stage is not appropriate in the state of lattice defects and in the crystal structure of the active species such as platinum and rare earth elements due to the inclusion of alumina.
【００１１】本発明は、上記従来技術の問題点に鑑みな
されたものであり、低温においても窒素酸化物を効率よ
く除去することができる装置を提供することを目的とす
る。The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an apparatus capable of efficiently removing nitrogen oxides even at a low temperature.
【００１２】[0012]
【課題を解決するための手段】本発明の窒素酸化物の除
去装置は、窒素酸化物を含有する気体の流路の前段に設
けられた白金またはパラジウムのうちの少なくとも一方
を有する第１触媒層と、該第１触媒層の後段に設けられ
たＡＢ’1-x Ｃ’x Ｏ3 （Ａはランタン、ストロンチウ
ム、セリウム、バリウム、カルシウムのうちの少なくと
も１種、Ｂ’はコバルト、鉄、ニッケル、クロム、マン
ガン、マグネウシムのうちの少なくとも１種、Ｃ’は白
金、パラジウムのうちの少なくとも一方、ｘは０．００
５≦ｘ≦０．２である）で示されるペロブスカイト型構
造の物質を有する第２触媒層とよりなることを特徴とす
るものである。A device for removing nitrogen oxides according to the present invention comprises a first catalyst layer having at least one of platinum and palladium provided in a preceding stage of a flow path of a gas containing nitrogen oxides. And AB ′ 1-x C ′ x O 3 (A is at least one of lanthanum, strontium, cerium, barium, and calcium, and B ′ is cobalt, iron, nickel provided in the latter stage of the first catalyst layer. , At least one of chromium, manganese, and magnesium, C ′ is at least one of platinum and palladium, and x is 0.00
5 ≦ x ≦ 0.2) and a second catalyst layer having a substance having a perovskite structure represented by the formula (5 ≦ x ≦ 0.2).
【００１３】[0013]
【作用】本発明の装置は、低温においても窒素酸化物を
効率よく除去することができる。これは、以下のような
作用を呈しているためと推察される。本発明の装置にお
ける前段に配置した第１触媒層では、白金またはパラジ
ウムの触媒作用による酸化反応によって、窒素酸化物で
あるＮＯが酸化されてＮＯ2 に変換する。白金またはパ
ラジウムは、その金属表面上の活性点でＮＯの吸着と活
性化、および酸素の吸着と活性化を促進するため上記変
換が効率よく行われる。The apparatus of the present invention can efficiently remove nitrogen oxides even at low temperatures. This is presumed to be due to the following effects. In the first catalyst layer arranged in the preceding stage in the device of the present invention, NO which is a nitrogen oxide is oxidized and converted into NO 2 by the oxidation reaction due to the catalytic action of platinum or palladium. Platinum or palladium promotes the adsorption and activation of NO and the adsorption and activation of oxygen at the active sites on the metal surface, so that the above conversion is efficiently performed.
【００１４】上記ＮＯ2 は、後段の第２触媒層で吸着さ
れた後、Ｎ2 、Ｏ2 、Ｎ2 Ｏ等に分解されて除去され
る。ＮＯガスのＮ−Ｏ結合エネルギが大きいためＮＯの
直接分解は起きにくいが、前段の第１触媒層でＮＯより
分解しやすいＮＯ2 に変換されるのでＮＯの除去が促進
される。この後段のＡＢ’1-x Ｃ’x Ｏ3 で示されるペ
ロブスカイト型構造のＣ’元素（白金またはパラジウ
ム）は、ペロブスカイト型構造の結晶格子に組み入れら
れているので、ＮＯからＮＯ2 への転化活性とＮＯ2 の
分解活性が大きく、また、格子欠陥（酸素欠陥部）が生
成し、ＮＯ2 の吸着量が増大する。The NO 2 is adsorbed by the second catalyst layer in the subsequent stage, decomposed into N 2 , O 2 , N 2 O and the like and removed. Direct decomposition of NO is unlikely to occur due to the large NO bond energy of NO gas, but the removal of NO is promoted because it is converted to NO 2 which is more easily decomposed than NO in the first catalyst layer in the preceding stage. Since the C'element (platinum or palladium) of the perovskite structure represented by AB ' 1-x C'x O 3 in the latter stage is incorporated in the crystal lattice of the perovskite structure, conversion from NO to NO 2 is performed. The activity and the decomposition activity of NO 2 are large, and lattice defects (oxygen defect portions) are generated, so that the adsorption amount of NO 2 is increased.
【００１５】また、ＡＢ’1-x Ｃ’x Ｏ3 中のＡ元素お
よびＢ’元素は、本質的にＮＯ2 等の吸着性能に優れる
アルカリ土類元素、遷移金属、希土類元素等で構成され
ているので、白金またはパラジウムの上記作用と相乗的
にＮＯ2 の吸着や分解が向上する。The elements A and B'in AB ' 1-x C'x O 3 are essentially composed of alkaline earth elements, transition metals, rare earth elements, etc., which have excellent adsorption performance for NO 2 and the like. Therefore, the adsorption and decomposition of NO 2 are enhanced synergistically with the above action of platinum or palladium.
【００１６】本発明において上記作用を呈する理由はま
だ明らかではないが、該１触媒層のみ、または第２触媒
層のみでは効果が不十分であることから、第１触媒層の
酸化性能と第２触媒層の分解性能との組み合わせ効果が
新たに生じたものであり、この作用は、２５０〜４００
℃のような低温でも活性が低下しない。特に、低温では
ＮＯの直接分解が起こりにくいが、本発明では、一度Ｎ
ＯをＮＯ2 に変換した後、吸着や分解によって除去する
ので有効である。Although the reason why the above-mentioned action is exhibited in the present invention is not clear yet, since the effect is insufficient with only the one catalyst layer or the second catalyst layer, the oxidation performance of the first catalyst layer and the second catalyst layer The combination effect with the decomposition performance of the catalyst layer is newly generated, and this action is 250 to 400
The activity does not decrease even at a low temperature such as ℃. In particular, direct decomposition of NO is unlikely to occur at low temperatures, but in the present invention, NO
It is effective because it is removed by adsorption or decomposition after converting O into NO 2 .
【００１７】[0017]
【発明の効果】本発明の装置は、低温においても窒素酸
化物を効率よく除去することができる。The device of the present invention can efficiently remove nitrogen oxides even at low temperatures.
【００１８】[0018]
【実施例】以下、本発明をより具体的にした具体例を説
明する。EXAMPLES Specific examples of the present invention will be described below.
【００１９】（具体例）本発明の窒素酸化物の除去装置
は、図１の例に示すように、窒素酸化物を含む気体の流
路の前段に配置された白金またはパラジウムのうちの少
なくとも一方よりなる第１触媒層１と、その後段に配置
されたペロブスカイト型構造の触媒よりなる第２触媒層
２との２種類の触媒層よりなる。図１の例では、窒素酸
化物を含む気体を導入するための導入口３と、上記２種
類の触媒層により処理した気体を装置外に排出するため
の排出口４が設けられ、流路の導入口３側に第１触媒層
１が配置され、流路の排出口４側に第２触媒層２が配置
されている。(Specific Example) As shown in the example of FIG. 1, the nitrogen oxide removing apparatus of the present invention comprises at least one of platinum and palladium arranged in the preceding stage of the flow path of the gas containing nitrogen oxide. The first catalyst layer 1 is composed of two types of catalyst layers, and the second catalyst layer 2 is composed of a catalyst having a perovskite structure and arranged in the subsequent stage. In the example of FIG. 1, an inlet 3 for introducing a gas containing nitrogen oxide and an outlet 4 for discharging the gas treated by the above two types of catalyst layers are provided outside the apparatus, and The first catalyst layer 1 is arranged on the side of the inlet 3 and the second catalyst layer 2 is arranged on the side of the outlet 4 of the flow path.
【００２０】なお、上記第１触媒層と第２触媒層との配
置順序を逆にすると、第１触媒層による酸化性能と第２
触媒層による分解性能との組み合わせ効果が消失し、低
温での活性が生じない。また、第１触媒層または第２触
媒層のみ、あるいは第１触媒層の触媒と第２触媒層の触
媒との混合体（ペレット形等）では本発明の上記効果は
得られない。If the order of arranging the first catalyst layer and the second catalyst layer is reversed, the oxidation performance of the first catalyst layer and the second catalyst layer
The combination effect with the decomposition performance due to the catalyst layer disappears, and the activity at low temperature does not occur. Further, the above effect of the present invention cannot be obtained with only the first catalyst layer or the second catalyst layer or with a mixture (pellet form or the like) of the catalyst of the first catalyst layer and the catalyst of the second catalyst layer.
【００２１】上記前段に配置される第１触媒層の触媒と
しては、ハニカム形状のコージェライト等の耐火性無機
担体上に白金またはパラジウムのうちの少なくとも一方
を分散担持して触媒としたものが好ましい。As the catalyst of the first catalyst layer arranged in the preceding stage, it is preferable that at least one of platinum and palladium is dispersed and carried on a refractory inorganic carrier such as a honeycomb-shaped cordierite to form a catalyst. .
【００２２】上記白金またはパラジウムよりなる触媒成
分を分散担持する際、該触媒成分をできるだけ高分散化
して担持するため、あらかじめアルミナ粉末を耐火無機
担体上に担持した後、触媒成分を担持するのが好まし
い。このアルミナ粉末は、白金またはパラジウムの吸着
点が表面上で均一に分布しているので、白金またはパラ
ジウムの高分散担持の作用を呈する。When the catalyst component made of platinum or palladium is dispersed and supported, it is preferable to support alumina catalyst on the refractory inorganic carrier in advance in order to support the catalyst component in a highly dispersed state. preferable. Since the adsorption points of platinum or palladium are uniformly distributed on the surface of this alumina powder, it exhibits the action of highly dispersed loading of platinum or palladium.
【００２３】具体的には、アルミナゾル、シリカゾル、
ジルコニアゾル等を結合剤として用い、アルミナ粉末を
ハニカム形状の耐火性無機担体上に被覆し、その後焼成
する。結合剤の配合量は、使用状態により異なるが、固
形分比で１〜１０重量％程度がよく、触媒活性を低下さ
せないため必要最低限を選択する。上記焼成後、ジニト
ロジアンミン白金（またはパラジウム）硝酸溶液等の白
金またはパラジウムを含有する溶液を用いて白金または
パラジウムを分散担持する。Specifically, alumina sol, silica sol,
Using a zirconia sol or the like as a binder, alumina powder is coated on a honeycomb-shaped refractory inorganic carrier, and then fired. The amount of the binder compounded varies depending on the use condition, but is preferably about 1 to 10% by weight in terms of solid content ratio, and the minimum necessary amount is selected because it does not lower the catalyst activity. After the firing, platinum or palladium is dispersed and supported by using a solution containing platinum or palladium such as dinitrodiammine platinum (or palladium) nitric acid solution.
【００２４】白金またはパラジウムよりなる触媒成分の
担持量は、アルミナ粉末に対して０．５〜３重量％の範
囲が好ましい。３重量％を越えて担持しても触媒成分の
粒子が粒子間で凝集を起こし、分散性が悪くなる。ま
た、０．５重量％未満では、触媒成分の活性が生かされ
にくい。The supported amount of the catalyst component composed of platinum or palladium is preferably in the range of 0.5 to 3% by weight based on the alumina powder. Even when the catalyst component is supported in an amount of more than 3% by weight, the particles of the catalyst component agglomerate among the particles, resulting in poor dispersibility. On the other hand, if it is less than 0.5% by weight, the activity of the catalyst component is hard to be utilized.
【００２５】なお、第１触媒層の触媒は、上記のように
ハニカム形状の他、ペレット形状でもよい。ペレット形
状とする場合には、アルミナ粉末に上記と同様の方法に
より白金またはパラジウムよりなる触媒成分を担持した
後、加圧成形し、更に破砕等を行い、ペレット形状とす
る。The catalyst of the first catalyst layer may be in the shape of pellet as well as the shape of honeycomb as described above. In the case of the pellet shape, the alumina powder is loaded with the catalyst component made of platinum or palladium by the same method as described above, then pressure-molded, and further crushed to obtain the pellet shape.
【００２６】後段に配置される第２触媒層の触媒として
は、ＡＢ’1-x Ｃ’x Ｏ3 （Ａはランタン（Ｌａ）、ス
トロンチウム（Ｓｒ）、セリウム（Ｃｅ）、バリウム
（Ｂａ）、カルシウム（Ｃａ）のうちの少なくとも１
種、Ｂ’はコバルト（Ｃｏ）、鉄（Ｆｅ）、ニッケル
（Ｎｉ）、クロム（Ｃｒ）、マンガン（Ｍｎ）、マグネ
シウム（Ｍｇ）のうちの少なくとも１種、Ｃ’は白金
（Ｐｔ）、パラジウム（Ｐｄ）のうちの少なくとも一
方、ｘは０．００５≦ｘ≦０．２である）で示されるペ
ロブスカイト型構造の物質とする。As the catalyst of the second catalyst layer arranged in the latter stage, AB ′ 1-x C ′ x O 3 (A is lanthanum (La), strontium (Sr), cerium (Ce), barium (Ba), At least one of calcium (Ca)
Seed, B'is at least one of cobalt (Co), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), and magnesium (Mg), and C'is platinum (Pt) and palladium. At least one of (Pd), x is 0.005 ≦ x ≦ 0.2) and has a perovskite structure.
【００２７】このペロブスカイト型構造の物質は、アル
カリ土類金属、遷移金属、希土類元素で構成されてお
り、これら元素は、ＮＯx 吸着性に富むものである。ま
た、異種金属イオンを組み合わせたとき、金属イオンの
関係からペロブスカイト型構造はゆがんだ形になり、格
子欠陥等が発生してＮＯx の吸着性や分解活性が発生す
る。ペロブスカイト型構造は、熱的に安定であり、耐熱
性がある。This perovskite type substance is composed of an alkaline earth metal, a transition metal, and a rare earth element, and these elements are rich in NO x adsorption. Further, when different kinds of metal ions are combined, the perovskite structure becomes distorted due to the relationship of the metal ions, and lattice defects and the like are generated to cause NO x adsorption and decomposition activity. The perovskite structure is thermally stable and heat resistant.
【００２８】ＡＢ’1-x Ｃ’x Ｏ3 で示されるペロブス
カイト型構造の複合酸化物は、図２に示すような理想格
子として単純立方格子の構造（ＡＢ’Ｏ3 ）の結晶格子
Ｂ’サイトにＣ’元素を組み入れたのものである。Ｂ’
とＣ’は６個のＯに囲まれ、６配位をとる。Ａは１２個
のＯに囲まれ、１２配位をとる。従って、理想格子とす
るには、Ｂ’とＣ’は６配位が保てるような原子価を持
つと同時にＢ’とＣ’のイオン半径ができるだけ近似し
ていることが必要である。Ｂ’とＣ’のイオン半径が異
なる程度に応じて結晶格子が歪んだ形になる。更にＢ’
に対してイオン半径の異なるＣ’の量が増加するにつれ
て結晶形の歪みが大きくなる。Ｂ’とＣ’のイオン半径
の関係によって一義的に決まらないが、上記分子式中の
ｘの値が０．２より大きくなると、歪みが大きくなり、
Ｃ’が結晶格子中に入らなくなる。一方、ｘの値が０．
００５未満でもＣ’は十分に結晶格子中に入るが、量が
少ないため実用上の触媒等の活性種としての効果を発揮
しない。The AB complex oxide having a perovskite structure represented by '1-x C' x O 3 , the structure of a simple cubic lattice as ideal lattice as shown in FIG. 2 (AB'O 3) of the crystal lattice B ' The C'element is incorporated into the site. B '
And C'are surrounded by 6 O's and are 6-coordinated. A is surrounded by 12 O's and has 12 coordinations. Therefore, in order to obtain an ideal lattice, it is necessary that B ′ and C ′ have valences capable of maintaining a hexacoordinate and at the same time the ionic radii of B ′ and C ′ are as close as possible. The crystal lattice becomes distorted depending on the extent to which the ionic radii of B ′ and C ′ differ. Further B '
On the other hand, as the amount of C ′ having different ionic radii increases, the strain of the crystal form increases. Although it is not uniquely determined by the relationship between the ionic radii of B ′ and C ′, when the value of x in the above molecular formula becomes larger than 0.2, the strain becomes large,
C'does not enter the crystal lattice. On the other hand, the value of x is 0.
Even if it is less than 005, C'will sufficiently enter the crystal lattice, but since it is too small, it will not exhibit the effect as an active species such as a catalyst in practical use.
【００２９】また、ＡＢ’1-x Ｃ’x Ｏ3 中のＣ’元素
（Ｐｔ、Ｐｄ）は、その９０％以上が結晶格子中に存在
するものがよい。これは、該Ｃ’元素（Ｐｔ、Ｐｄ）の
大部分が粒子として微細化（約２Å）し、触媒等の活性
種として分散度が向上し、ＮＯ2 の吸着や分解作用が一
層効果的となるためである。Further, 90% or more of the C'elements (Pt, Pd) in AB ' 1-x C'x O 3 are preferably present in the crystal lattice. This is because most of the C'elements (Pt, Pd) are made finer as particles (about 2Å), the dispersibility is improved as active species such as catalysts, and NO 2 adsorption and decomposition actions are more effective. This is because
【００３０】また、ＡＢ’1-x Ｃ’x Ｏ3 のペロブスカ
イト構造において、Ｂ’、Ｃ’はそれぞれ異なるイオン
サイズの格子中にあるため、その組み合わせによっては
ペロブスカイト構造が適度に歪んでいる。また、Ｂ’、
Ｃ’との原子価が異なる場合、電子補償効果等によって
活性が向上する利点がある。これらの場合、ペロブスカ
イト構造は適度な構造の歪みと格子欠陥を有し、該格子
欠陥部等がＮＯ2 の吸着と分解を促進させる。Further, in the perovskite structure of AB '1-x C' x O 3, B ', C' is due to the different lattice ion size, respectively, the perovskite structure is distorted moderately by the combination. Also, B ',
When the valence is different from that of C ′, there is an advantage that the activity is improved due to an electron compensation effect or the like. In these cases, the perovskite structure has an appropriate strain and lattice defect, and the lattice defect portion or the like promotes adsorption and decomposition of NO 2 .
【００３１】このペロブスカイト型構造の物質よりなる
触媒は、どのような形状でもよく、例えば、図３および
図４に示すような多数のセル２４を有するハニカム形状
のコージェライト等の耐火性無機担体２２上に該ペロブ
スカイト型構造の物質２１を分散担持したハニカム形状
のもの２（更に図４のように、担体２２とペロブスカイ
ト型構造の物質２１との間にアルミナコート層２３を設
けてもよい）、あるいはペロブスカイト型構造の物質の
粉末をペレット形状に成形したもの等が挙げられる。The catalyst made of the substance having the perovskite structure may have any shape, for example, a refractory inorganic carrier 22 such as a honeycomb-shaped cordierite having a large number of cells 24 as shown in FIGS. 3 and 4. A honeycomb-shaped material 2 on which the substance 21 having the perovskite structure is dispersed and supported (as shown in FIG. 4, an alumina coat layer 23 may be provided between the carrier 22 and the substance 21 having the perovskite structure). Alternatively, a powder of a substance having a perovskite structure is formed into a pellet shape.
【００３２】ペロブスカイト型構造の物質をハニカム形
状の担体に担持した形態では、該ペロブズカイト型構造
の物質の望ましい担持量は、ハニカム形状の担体１ｌ容
量中に１０〜３００ｇ担持するのがよい。この場合、Ｐ
ｔまたはＰｄ量がハニカム形状の担体１ｌ容量中に０．
５〜３ｇ担持される。ＰｔまたはＰｄ組成の多いペロブ
ズカイト構造の物質の場合は担持量を少なくするとよ
い。In the case where the substance having the perovskite structure is supported on the honeycomb-shaped carrier, the desirable amount of the substance having the perovskite structure is preferably 10 to 300 g per 1 l of the honeycomb-shaped carrier. In this case, P
The amount of t or Pd is 0.
Carry 5 to 3 g. In the case of a substance having a perovskite structure having a large Pt or Pd composition, it is advisable to reduce the supported amount.
【００３３】第２触媒層の形成方法としては、ペロブス
カイト型構造の物質よりなる触媒を調製し、その後触媒
層を形成する方法がある。また、本発明者らが開発した
触媒の製造方法もある（特願平４−２７５０１９号）。As a method of forming the second catalyst layer, there is a method of preparing a catalyst composed of a substance having a perovskite structure and then forming the catalyst layer. There is also a catalyst production method developed by the present inventors (Japanese Patent Application No. 4-275019).
【００３４】この方法について詳細に説明する。This method will be described in detail.
【００３５】上記のペロブスカイト型構造の複合酸化物
を構成する金属元素の塩とクエン酸とを溶解した水溶液
を調製し（第１工程）、該水溶液を乾燥して上記金属元
素のクエン酸錯体を形成し（第２工程）、該クエン酸錯
体を真空中または不活性ガス中３５０℃以上で加熱・仮
焼成し（第３工程）、その後酸化雰囲気で焼成する（第
４工程）。An aqueous solution is prepared by dissolving a salt of a metal element which constitutes the above complex oxide having a perovskite structure and citric acid (first step), and the aqueous solution is dried to form a citric acid complex of the metal element. It is formed (second step), the citric acid complex is heated and pre-baked at 350 ° C. or higher in vacuum or in an inert gas (third step), and then baked in an oxidizing atmosphere (fourth step).
【００３６】第１工程において、金属元素の塩とクエン
酸とを溶解した水溶液を調製する。In the first step, an aqueous solution in which a salt of a metal element and citric acid are dissolved is prepared.
【００３７】第１工程における金属元素の塩としては、
硝酸塩または酢酸塩がよい。これは、第３工程の仮焼成
で金属元素以外の残存物を分解できるためである。例え
ば、塩酸塩の場合、塩素が残存して触媒活性や吸着活性
等の特性に影響を与える。As the salt of the metal element in the first step,
Nitrate or acetate is preferred. This is because the remaining substances other than the metal element can be decomposed by the calcination in the third step. For example, in the case of a hydrochloride, chlorine remains and affects characteristics such as catalytic activity and adsorption activity.
【００３８】例えば、ペロブスカイト型構造の複合酸化
物（ＡＢ’1-x Ｃ’x Ｏ3 ）のＡ元素の硝酸塩として
は、Ｌａ（ＮＯ3 ）3 ・６Ｈ2 Ｏ、Ｓｒ（ＮＯ3 ）2 、
Ｃｅ（ＮＯ3 ）3 ・６Ｈ2 Ｏ、Ｂａ（ＮＯ3 ）2 、Ｃａ
（ＮＯ3 ）3 ・４Ｈ2 Ｏ等が挙げられ、また、Ａ元素の
酢酸塩としては、Ｌａ（ＣＨ3 ＣＯＯ）3 ・３／２Ｈ2
Ｏ、Ｓｒ（ＣＨ3 ＣＯＯ）3 ・１／２Ｈ2 Ｏ、Ｃｅ（Ｃ
Ｈ3 ＣＯＯ）3 ・Ｈ2 Ｏ、Ｂａ（ＣＨ3 ＣＯＯ）2 、Ｃ
ａ（ＣＨ3 ＣＯＯ）2 ・Ｈ2 Ｏ等が挙げられる。Ｂ’元
素の硝酸塩としては、Ｃｏ（ＮＯ3 ）2 ・６Ｈ2 Ｏ、Ｆ
ｅ（ＮＯ3 ）3 ・９Ｈ2 Ｏ等が挙げられる。また、Ｂ’
元素の酢酸塩としては、Ｃｏ（ＣＨ3 ＣＯＯ）2 ・４Ｈ
2 Ｏ等が挙げられる。Ｃ’元素の硝酸塩としては、ジニ
トロジアンミン白金硝酸塩、ジニトロジアンミンパラジ
ウム硝酸塩等が挙げられる。また、Ｐｔ（ＮＨ3 ）
4 （ＯＨ）2 も上記ジニトロジアンミン白金硝酸塩の代
用として使用することができる。For example, as the nitrate of the A element of the complex oxide (AB ' 1-x C'x O 3 ) having the perovskite structure, La (NO 3 ) 3 .6H 2 O, Sr (NO 3 ) 2 ,
Ce (NO 3) 3 · 6H 2 O, Ba (NO 3) 2, Ca
(NO 3) 3 · 4H 2 O , and the like, and as the acetic acid salt of the element A, La (CH 3 COO) 3 · 3 / 2H 2
O, Sr (CH 3 COO) 3 1 / 2H 2 O, Ce (C
H 3 COO) 3 · H 2 O, Ba (CH 3 COO) 2 , C
a (CH 3 COO) 2 · H 2 O , and the like. The nitrate B 'element, Co (NO 3) 2 · 6H 2 O, F
e (NO 3) 3 · 9H 2 O , and the like. Also, B '
The acetate salt of the element, Co (CH 3 COO) 2 · 4H
2 O and the like. Examples of the nitrate of the C ′ element include dinitrodiammine platinum nitrate and dinitrodiammine palladium nitrate. In addition, Pt (NH 3 )
4 (OH) 2 can also be used as a substitute for the above dinitrodiammine platinum nitrate.
【００３９】これら金属元素の塩は上記式ＡＢ’
1-x Ｃ’x Ｏ3 の組成となるような配合割合とする。The salts of these metal elements are represented by the above formula AB '.
The blending ratio is such that the composition is 1-x C'x O 3 .
【００４０】クエン酸の配合量としては、形成するペロ
ブスカイト型構造の複合酸化物１モルに対して２〜２．
４モルの範囲とするのがよい。該配合量が２モル未満で
は錯体形成が困難となる場合があり、２．４モルを越え
ると錯体形成は十分であるが、金属元素の均一混合が困
難となる場合がある。The amount of citric acid to be added is 2 to 2 with respect to 1 mol of the complex oxide having the perovskite structure.
It is preferably in the range of 4 mol. If the amount is less than 2 mol, complex formation may be difficult, and if it exceeds 2.4 mol, complex formation may be sufficient, but uniform mixing of metal elements may be difficult.
【００４１】金属元素の塩とクエン酸とを溶解した水溶
液を調製する方法としては、例えば、金属元素の塩をイ
オン交換水に溶解し、また、別のイオン交換水にクエン
酸を溶解し、この両者を混合する方法がある。As a method for preparing an aqueous solution in which a salt of a metal element and citric acid are dissolved, for example, a salt of a metal element is dissolved in ion-exchanged water, and citric acid is dissolved in another ion-exchanged water. There is a method of mixing both.
【００４２】第２工程では、上記水溶液を乾燥すること
により金属元素のクエン酸錯体を形成する。In the second step, the citric acid complex of the metal element is formed by drying the aqueous solution.
【００４３】第２工程における乾燥条件としては、クエ
ン酸錯体が分解しない温度範囲ですみやかに水分を除去
する条件（例えば、室温〜１５０℃、２〜１２時間）が
適する。As the drying conditions in the second step, the conditions for removing moisture promptly within a temperature range where the citric acid complex is not decomposed (for example, room temperature to 150 ° C., 2 to 12 hours) are suitable.
【００４４】第３工程では、上記金属元素のクエン酸錯
体を真空中または不活性ガス中３５０℃以上で加熱して
仮焼成する。In the third step, the citric acid complex of the metal element is heated at 350 ° C. or higher in vacuum or in an inert gas to be calcined.
【００４５】この仮焼成の雰囲気が酸化雰囲気では、ク
エン酸錯体からのクエン酸および金属元素の塩からの残
存物（有機物、硝酸根等）の分解が促進されない。その
ため、真空中でも不活性ガス中とする。なお、真空の方
が不活性ガスよりも上記分解が促進されるので好まし
い。When the calcination atmosphere is an oxidizing atmosphere, decomposition of citric acid from the citric acid complex and residues (organic substances, nitrates, etc.) from salts of metal elements is not promoted. Therefore, it is kept in an inert gas even in a vacuum. It should be noted that a vacuum is more preferable than an inert gas because the above decomposition is promoted.
【００４６】加熱温度が３５０℃未満では、クエン酸お
よび出発原料である金属元素の塩からの残存物（有機
物、硝酸根等）が加熱分解できず残存してしまう。ま
た、加熱温度の上限は５００℃とするのがよい。５００
℃を越えても差し支えないが、仮焼成としては５００℃
までで十分であり、それ以上はエネルギーのムダや仮焼
成用装置の損傷が生じるので好ましくない。If the heating temperature is lower than 350 ° C., the residual substances (organic substances, nitrate radicals, etc.) from the salt of the citric acid and the metal element as the starting material cannot be thermally decomposed and remain. The upper limit of the heating temperature is preferably 500 ° C. 500
There is no problem even if the temperature exceeds ℃, but 500 ℃ for calcination
Is sufficient, and waste of energy and damage to the pre-baking device are not preferable.
【００４７】なお、加熱する際、８０℃からゆっくり昇
温するのがよい。これは、１３０℃付近からクエン酸お
よび金属元素の塩からの残存物が分解しはじめ、この範
囲の温度を時間をかけることにより該分解が促進するた
めである。３５０℃以上では約２〜３時間ほど保持する
のがよい。When heating, it is preferable to slowly raise the temperature from 80 ° C. This is because the residue from the citric acid and the salt of the metal element starts to decompose from around 130 ° C., and the decomposition is accelerated by taking a temperature in this range for a long time. At 350 ° C. or higher, it is preferable to hold for about 2 to 3 hours.
【００４８】この工程により仮焼成体を形成する。A calcination body is formed by this process.
【００４９】第４工程では、上記仮焼成体を焼成する。In the fourth step, the calcination body is fired.
【００５０】焼成方法としては、どのような方法でもよ
いが、酸化物を形成するため大気中のような酸素が存在
する酸化雰囲気とする。The firing method may be any method, but in order to form an oxide, an oxidizing atmosphere in which oxygen is present, such as in the air, is used.
【００５１】また、焼成温度としては、７００〜９５０
℃の範囲が好ましい。７００℃未満の温度においてはペ
ロブスカイト型構造の結晶が成長しにくい。また、９５
０℃を越える温度では、結晶成長が進み過ぎるため、適
度な格子欠陥を有して格子内に存在していた貴金属が結
晶格子外へ出てしまったり、比表面積が低下して活性が
低下するおそれがある。The firing temperature is 700 to 950.
The range of ° C is preferred. At a temperature below 700 ° C., crystals having a perovskite structure are difficult to grow. Also, 95
When the temperature exceeds 0 ° C., the crystal growth proceeds too much, so that the precious metal having an appropriate lattice defect and existing in the lattice may come out of the crystal lattice, or the specific surface area may be reduced to lower the activity. There is a risk.
【００５２】また、焼成時間は、１時間程度でも焼成体
が得られるが、長時間ほど結晶化率の高い複合酸化物が
得られるため、２〜５時間が好ましい。The firing time is about 1 hour, but a fired body can be obtained. However, a longer time is preferable because a composite oxide having a higher crystallization rate can be obtained.
【００５３】ペロブスカイト型構造の複合酸化物は、コ
ージエライト等の耐火性無機担体上に分散担持してハニ
カム構造の触媒層とするのが好ましい。この分散担持す
る際、ペロブスカイト型構造の触媒をできるだけ高分散
化して担持するため、分散媒体としてＰＶＡ（ポリビニ
ールアルコール）やカーボンブラック等を使用するのが
よい。また、分散剤や結合剤として、アルミナゾル、シ
リカゾル、ジルコニアゾル等が使用できる。その使用量
としては、目的、使用状態で異なるが、固形分比で３〜
１５重量％程度がよく、触媒活性を低下させないため必
要最小限を選択する。The composite oxide having a perovskite structure is preferably dispersed and carried on a refractory inorganic carrier such as cordierite to form a honeycomb structure catalyst layer. When carrying this dispersion, it is preferable to use PVA (polyvinyl alcohol), carbon black, or the like as a dispersion medium in order to carry the catalyst having a perovskite structure as highly dispersed as possible. Further, as the dispersant or binder, alumina sol, silica sol, zirconia sol or the like can be used. The amount used varies depending on the purpose and state of use, but is 3 to 3 in terms of solid content ratio.
About 15% by weight is preferable, and the minimum necessary amount is selected because it does not reduce the catalytic activity.
【００５４】また、ペロブスカイト型構造の触媒のみか
らなるペレット状のものを作成する場合には、ペロブス
カイト型構造の触媒の粉末を、加圧成形機等を用いてペ
レット形状とした後、流通管内に充填して触媒層とす
る。Further, in the case of producing a pellet-like one consisting of only the catalyst having the perovskite structure, the catalyst powder having the perovskite structure is made into a pellet form by using a pressure molding machine or the like, and then the powder is placed in the flow pipe. It is filled to form a catalyst layer.
【００５５】前段の第１触媒層と後段の第２触媒層と
は、直接に連結するのが好ましい。また、前段を通過し
たガス成分が変化しない範囲で後段との間に管を配置し
てもよい。第１触媒層と第２触媒層との組み合わせたも
のが複数組連結された場合にはＮＯx の除去効果がさら
に向上する。It is preferable that the first catalyst layer at the front stage and the second catalyst layer at the rear stage are directly connected. Further, a pipe may be arranged between the gas passage and the latter stage within a range where the gas component passing through the former stage does not change. When a plurality of combinations of the first catalyst layer and the second catalyst layer are connected, the NO x removal effect is further improved.
【００５６】また、第１触媒層と第２触媒層との触媒の
割合について特に限定はない。ＮＯx 中のＮＯ成分の量
または全ＮＯx 量に応じて第１触媒層または第２触媒層
の触媒量を選択すればよい。The ratio of the catalyst in the first catalyst layer to the second catalyst layer is not particularly limited. The first catalyst may be selected amount of the catalyst layer or the second catalyst layer depending on the amount or the total amount of NO x NO component in NO x.
【００５７】窒素酸化物を含有する気体を装置内に導入
する導入口および処理した気体を排出する排出口は、形
状的に特に限定されない。負圧がかからない形状であれ
ばよい。The inlet for introducing the gas containing nitrogen oxide into the apparatus and the outlet for discharging the treated gas are not particularly limited in shape. Any shape is acceptable as long as negative pressure is not applied.
【００５８】また、本発明では、図１に示すように、触
媒層の周囲にリテーナ９１、シール材９２、ワイヤーネ
ット９３を設けてもよい。Further, in the present invention, as shown in FIG. 1, a retainer 91, a sealing material 92, and a wire net 93 may be provided around the catalyst layer.
【００５９】本発明の装置は、特に酸素過剰下の還元剤
の乏しい状態や５００℃以下の低温でも高効率で窒素酸
化物を除去できるため、ディーゼルエンジンやガソリン
エンジン等の内燃機関から排出される排ガス、あるいは
硝酸製造工場からの排ガス中の窒素酸化物の除去装置等
として利用できる。Since the apparatus of the present invention can remove nitrogen oxides with high efficiency even in a state where the reducing agent is scarce in excess of oxygen or at a low temperature of 500 ° C. or less, it is discharged from an internal combustion engine such as a diesel engine or a gasoline engine. It can be used as a device for removing exhaust gas or nitrogen oxides in exhaust gas from a nitric acid manufacturing plant.
【００６０】内燃機関から排出される排ガス中の窒素酸
化物を除去する場合には、本発明の装置を排気管の途中
に配置する。また、パティキュレートフィルターを併用
する場合には、本発明の装置の上流側に配置し、また、
酸化触媒を併用する場合には、本発明の装置の下流側に
配置するとよい。When removing nitrogen oxides in the exhaust gas discharged from the internal combustion engine, the device of the present invention is arranged in the middle of the exhaust pipe. Further, when the particulate filter is used in combination, it is arranged on the upstream side of the device of the present invention,
When an oxidation catalyst is also used, it may be placed downstream of the device of the present invention.
【００６１】以下、本発明の実施例を説明する。Examples of the present invention will be described below.
【００６２】（実施例） 〔第１触媒の調製〕グレース社製γ−アルミナ粉末１０
０ｇをビーカーに入れ、イオン交換水３００ｍｌを加え
てかきまぜた。この溶液に、白金含有量４．４７重量％
のジニトロジアンミン白金硝酸溶液３７．２９ｇとを加
え、よくかきませた。(Example) [Preparation of first catalyst] γ-alumina powder 10 manufactured by Grace Co.
0 g was put in a beaker, 300 ml of ion-exchanged water was added, and the mixture was stirred. The solution contains platinum content of 4.47% by weight.
37.29 g of a dinitrodiammine platinum nitric acid solution of was added and thoroughly scratched.
【００６３】この懸濁液をひきつづきかきまぜながら電
気ヒータで加熱し、水分を蒸発させ、白金粒子を均一に
アルミナ粉末の表面に分散担持させた。ひきつづき該白
金担持アルミナ粉末をるつぼに移し、大気中４００℃で
１時間加熱して白金担持アルミナ粉末に残留した硝酸根
を分解除去することにより灰色の白金担持アルミナ触媒
粉末を得た。該触媒粉末の白金含有量はγ−アルミナ粉
末１２０ｇに対して白金２ｇであった。The suspension was continuously stirred and heated with an electric heater to evaporate the water content, and the platinum particles were uniformly dispersed and supported on the surface of the alumina powder. Subsequently, the platinum-supported alumina powder was transferred to a crucible and heated in air at 400 ° C. for 1 hour to decompose and remove the nitrate radicals remaining in the platinum-supported alumina powder to obtain a gray platinum-supported alumina catalyst powder. The platinum content of the catalyst powder was 2 g of platinum based on 120 g of γ-alumina powder.
【００６４】〔第２触媒の調製〕硝酸ランタン２１．６
７ｇ（０．０５モル）をイオン交換水５０ｍｌに溶解し
た。また、酢酸コバルト１１．５６ｇ（０．０４５モ
ル）をイオン交換水５０ｍｌに溶解した。また、ジニト
ロジアンミン白金硝酸２１．３５ｇ（０．００５モル）
をイオン交換水３０ｍｌに溶解した。また、クエン酸２
５．２２ｇ（０．１２モル）をイオン交換水１２０ｍｌ
に溶解した。これら４種類の水溶液を混合し、約２５０
ｍｌの混合溶液を作製した。[Preparation of Second Catalyst] Lanthanum nitrate 21.6
7 g (0.05 mol) was dissolved in 50 ml of deionized water. Further, 11.56 g (0.045 mol) of cobalt acetate was dissolved in 50 ml of ion-exchanged water. In addition, dinitrodiammine platinum nitric acid 21.35 g (0.005 mol)
Was dissolved in 30 ml of deionized water. Also, citric acid 2
5.22 g (0.12 mol) of ion-exchanged water 120 ml
Dissolved in. Approximately 250 by mixing these four types of aqueous solutions
A mixed solution of ml was prepared.
【００６５】この混合水溶液をエバポレータで減圧しな
がら８０℃の湯浴中で約４時間かけて蒸発乾固させ、ク
エン酸錯体を作製した。The mixed aqueous solution was evaporated to dryness in a hot water bath at 80 ° C. for about 4 hours under reduced pressure with an evaporator to prepare a citric acid complex.
【００６６】このクエン酸錯体を真空ポンプで減圧（１
０-2ｔｏｒｒ以下）しながらマントルヒータにより８０
℃から４００℃まで温度が急激に上昇しないようにゆっ
くり昇温した。なお、１３０℃付近から酢酸とクエン酸
とが分解しはじめた。２５０〜４００℃で硝酸根が分解
し黄色のガスが発生するので、この発生ガスがなくなる
ことを確認してこの熱処理を完了した（約３時間）。こ
れにより有機物および硝酸根を除去した仮焼成体を作製
した。The citric acid complex was depressurized (1
0 -2 torr or less) 80 by a mantle heater while
The temperature was slowly raised from 0 ° C to 400 ° C so that the temperature did not rise sharply. Note that acetic acid and citric acid began to decompose at around 130 ° C. At 250 to 400 ° C., nitrate radicals were decomposed and a yellow gas was generated. Therefore, it was confirmed that the generated gas disappeared, and this heat treatment was completed (about 3 hours). As a result, a pre-baked body from which organic substances and nitrates were removed was prepared.
【００６７】この仮焼成体を粉末にした後、るつぼに入
れて空気雰囲気で７５０℃の温度で３時間焼成した。This calcinated body was made into a powder, put into a crucible, and calcinated in an air atmosphere at a temperature of 750 ° C. for 3 hours.
【００６８】これにより、ＬａＣｏ0.9 Ｐｔ0.1 Ｏ3 で
示される組成のペロブスカイト型構造複合酸化物を製造
した。As a result, a perovskite structure complex oxide having a composition represented by LaCo 0.9 Pt 0.1 O 3 was produced.
【００６９】また、上記と同様にして、ＬａＦｅ0.8 Ｐ
ｔ0.2 Ｏ3 、Ｓｒ0.9 Ｂａ0.1 Ｃｏ0.85Ｐｄ0.15Ｏ3 、
Ｌａ0.8 Ｓｒ0.2 Ｃｒ0.95Ｐｔ0.05Ｏ3 、ＬａＮｉ0.98
Ｐｔ0.02Ｏ3 で示される組成のペロブスカイト型構造複
合酸化物も製造した。In the same manner as above, LaFe 0.8 P
t 0.2 O 3 , Sr 0.9 Ba 0.1 Co 0.85 Pd 0.15 O 3 ,
La 0.8 Sr 0.2 Cr 0.95 Pt 0.05 O 3 , LaNi 0.98
A perovskite structure composite oxide having a composition represented by Pt 0.02 O 3 was also manufactured.
【００７０】〔窒素酸化物除去装置の作製〕上記第１触
媒、第２触媒いずれの場合も、焼成体の粉末を錠剤成形
機で加圧して厚さ約１ｍｍの板状にした後、破砕して粒
径１〜２ｍｍのペレット状にした。このペレット状の第
１触媒１０ｃｃ（約４ｇ）を内燃機関から排出される排
ガスを処理するための流通式固定床の前段に配置し、さ
らにペレット状の第２触媒１０ｃｃ（約１３ｇ）を流通
式固定床の後段に配置した。これにより、図５に示すよ
うに、流通式固定床５の先端に設けられ、排ガスを導入
するための導入口３と、排ガスの流路の前段部に設けら
れた第１触媒層１と、その後段部に設けられた第２触媒
層２と、流通式固定床５の先端に設けられ、上記２種類
の触媒層により処理された排ガスを排出するための排出
口４とよりなる窒素酸化物除去装置を作製した。この装
置は、導入口３と第１触媒層１との間、および第２触媒
層２と排出口４との間に充填触媒が外部に流出しないよ
うにルーバー６が設けられており、導入した排ガスを触
媒と接触させ浄化した後、排出するようになっている。
流通式固定床５の外周には、ガラスウールよりなる断熱
材７が設けられている。また、第１触媒層１、および第
２触媒層２には、触媒を充填または取り出すための充填
口８が設けられている。[Production of Nitrogen Oxide Removal Device] In both the first catalyst and the second catalyst, the powder of the calcined body was pressed by a tablet molding machine to form a plate having a thickness of about 1 mm, which was then crushed. To form a pellet having a particle size of 1 to 2 mm. This pellet-shaped first catalyst 10cc (about 4g) is placed in front of the flow type fixed bed for treating the exhaust gas discharged from the internal combustion engine, and the pellet-shaped second catalyst 10cc (about 13g) is placed in the flow type. It was placed after the fixed bed. As a result, as shown in FIG. 5, an inlet 3 provided at the tip of the flow type fixed bed 5 for introducing the exhaust gas, and a first catalyst layer 1 provided at the front stage of the flow path of the exhaust gas, Nitrogen oxide comprising a second catalyst layer 2 provided at the subsequent stage and an exhaust port 4 provided at the tip of the flow type fixed bed 5 for exhausting the exhaust gas treated by the above two types of catalyst layers. A removal device was produced. In this device, a louver 6 is provided between the introduction port 3 and the first catalyst layer 1 and between the second catalyst layer 2 and the discharge port 4 so that the filled catalyst does not flow out to the outside. The exhaust gas comes into contact with the catalyst to be purified and then discharged.
A heat insulating material 7 made of glass wool is provided on the outer periphery of the flow type fixed bed 5. Further, the first catalyst layer 1 and the second catalyst layer 2 are provided with a filling port 8 for filling or removing the catalyst.
【００７１】〔装置の評価〕上記の装置を用いて、以下
のようにＮＯx の浄化性能評価試験を行った。[Evaluation of Device] Using the above device, a NO x purification performance evaluation test was conducted as follows.
【００７２】渦流式ディーゼルエンジン（２．４５ｌ）
の排ガス管に上記装置を、排ガスが導入口３より導入す
るように配置した。このエンジンを国内１０モード試験
条件で稼働させて実排ガスを発生させた。空間速度９６
０００／時間で上記実排ガスを装置中に導入し、装置の
排出口４におけるＮＯx 濃度を自動車排ガス分析計
（（株）堀場製作所製）で測定した。本装置を使用しな
い場合のＮＯx 濃度を基準としてＮＯx 浄化率を算出し
た。Eddy current type diesel engine (2.45l)
The above-mentioned device was arranged in the exhaust gas pipe of No. 2 such that the exhaust gas was introduced from the inlet 3. This engine was operated under domestic 10-mode test conditions to generate actual exhaust gas. Space velocity 96
The actual exhaust gas was introduced into the apparatus at 000 / hour, and the NO x concentration at the exhaust port 4 of the apparatus was measured by an automobile exhaust gas analyzer (manufactured by Horiba, Ltd.). The NO x purification rate was calculated based on the NO x concentration when this device was not used.
【００７３】なお、本実施例では、第２触媒の種類を変
化させた５種類の形態（実施例１〜５）で実施した。It should be noted that in this example, the embodiment was carried out in five types of modes in which the type of the second catalyst was changed (Examples 1 to 5).
【００７４】（比較例１）第１触媒層と第２触媒層との
逆設置 第２触媒のペレット１０ｃｃ（約１３ｇ）を流通式固定
床５の前段部（排ガス流路の前段）に配置し、第１触媒
のペレット１０ｃｃ（約４ｇ）を流通式固定床５の後段
部（排ガス流路の後段）に配置し、その他は上記実施例
と同様にした装置を作製し、上記実施例と同様にしてＮ
Ｏx の浄化性能評価試験を行った。(Comparative Example 1) Reverse installation of the first catalyst layer and the second catalyst layer The second catalyst pellet 10 cc (about 13 g) was placed in the front part of the flow type fixed bed 5 (the front part of the exhaust gas passage). , 10 cc (about 4 g) of the pellets of the first catalyst were placed in the latter stage of the flow-type fixed bed 5 (the latter stage of the exhaust gas flow passage), and the others were manufactured in the same manner as in the above-mentioned example, and the same as the above-mentioned example. Then N
An O x purification performance evaluation test was conducted.
【００７５】（比較例２）第１触媒層の単独設置 第１触媒のペレット２０ｃｃ（約８ｇ）を流通式固定床
５の前段部（排ガス流路の前段）に配置し、流通式固定
床５の後段部（排ガス流路の後段）には触媒を配置せ
ず、その他は上記実施例と同様にした装置を作製し、上
記実施例と同様にしてＮＯx の浄化性能評価試験を行っ
た。(Comparative Example 2) Single installation of the first catalyst layer 20 cc (about 8 g) of the first catalyst was placed in the front part of the flow type fixed bed 5 (the front stage of the exhaust gas flow passage), and the flow type fixed bed 5 A catalyst was not arranged in the latter part (the latter part of the exhaust gas flow path), and an apparatus was manufactured in the same manner as in the above example except for the above, and a NO x purification performance evaluation test was conducted in the same manner as in the above example.
【００７６】（比較例３）第２触媒層の単独設置 第２触媒のペレット２０ｃｃ（約２６ｇ）を流通式固定
床５の後段部（排ガス流路の後段）に配置し、流通式固
定床５の前段部（排ガス流路の前段）には触媒を配置せ
ず、その他は上記実施例と同様にした装置を作製し、上
記実施例と同様にしてＮＯx の浄化性能評価試験を行っ
た。(Comparative Example 3) Single installation of second catalyst layer 20 cc (about 26 g) of the second catalyst was placed in the latter part of the flow type fixed bed 5 (the latter stage of the exhaust gas flow path), and the flow type fixed bed 5 A catalyst was not arranged in the front stage part (the front stage of the exhaust gas flow path), and the other devices were manufactured in the same manner as in the above examples, and the NO x purification performance evaluation test was conducted in the same manner as in the above examples.
【００７７】（比較例４）第１触媒と第２触媒との混合
体 第１触媒のペレット１０ｃｃ（約４ｇ）と第２触媒のペ
レット１０ｃｃ（約１３ｇ）とをよく混合した後、流通
式固定床５の前段部（排ガス流路の前段）に配置し、流
通式固定床５の後段部（排ガス流路の後段）には触媒を
配置せず、その他は上記実施例と同様にした装置を作製
し、上記実施例と同様にしてＮＯx の浄化性能評価試験
を行った。(Comparative Example 4) Mixture of first catalyst and second catalyst After thoroughly mixing 10 cc (about 4 g) of pellets of the first catalyst and 10 cc (about 13 g) of pellets of the second catalyst, flow-type fixing An apparatus similar to that of the above-described embodiment is provided in the front stage of the floor 5 (the front stage of the exhaust gas passage), and the catalyst is not provided in the rear stage of the flow-type fixed bed 5 (the rear stage of the exhaust gas passage). It was produced and a NO x purification performance evaluation test was conducted in the same manner as in the above example.
【００７８】上記本実施例および比較例におけるＮＯx
の浄化性能評価試験の結果を表１に示す。NO x in the above Examples and Comparative Examples
Table 1 shows the results of the purification performance evaluation test.
【００７９】[0079]
【表１】 [Table 1]
【００８０】表１より明らかなように、本実施例（実施
例１〜５）の装置の方が比較例（比較例１〜４）のもの
よりＮＯx の浄化性能に優れていることが分かる。As is clear from Table 1, the device of this example (Examples 1 to 5) is superior to the comparative example (Comparative examples 1 to 4) in NO x purification performance. .
【図１】本発明の窒素酸化物除去装置の一例を示す断面
図FIG. 1 is a sectional view showing an example of a nitrogen oxide removing device of the present invention.
【図２】ペロブスカイト構造の結晶格子を示す概念図FIG. 2 is a conceptual diagram showing a crystal lattice having a perovskite structure.
【図３】本発明の窒素酸化物除去装置の一例における触
媒層を示す斜視図FIG. 3 is a perspective view showing a catalyst layer in an example of a nitrogen oxide removing device of the present invention.
【図４】本発明の窒素酸化物除去装置の一例における触
媒層を示す断面図FIG. 4 is a sectional view showing a catalyst layer in an example of a nitrogen oxide removing device of the present invention.
【図５】本発明の実施例における窒素酸化物除去装置を
示す断面図FIG. 5 is a sectional view showing a nitrogen oxide removing device according to an embodiment of the present invention.
１ 第１触媒層 ２ 第２触媒層 ３ 導入口 ４ 排出口 ５ 流通式固定床 1 1st catalyst layer 2 2nd catalyst layer 3 introduction port 4 discharge port 5 flow type fixed bed
───────────────────────────────────────────────────── フロントページの続き (72)発明者 植野 秀章 愛知県豊田市トヨタ町１番地 トヨタ自動 車株式会社内 (72)発明者 水野 達司 愛知県豊田市トヨタ町１番地 トヨタ自動 車株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Ueno 1 Toyota-cho, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Tatsushi Mizuno 1-cho, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd.
Claims (1)
に設けられた白金またはパラジウムのうちの少なくとも
一方を有する第１触媒層と、 該第１触媒層の後段に設けられたＡＢ’1-x Ｃ’x Ｏ3
（Ａはランタン、ストロンチウム、セリウム、バリウ
ム、カルシウムのうちの少なくとも１種、Ｂ’はコバル
ト、鉄、ニッケル、クロム、マンガン、マグネシウムの
うちの少なくとも１種、Ｃ’は白金、パラジウムのうち
の少なくとも一方、ｘは０．００５≦ｘ≦０．２であ
る）で示されるペロブスカイト型構造の物質を有する第
２触媒層とよりなることを特徴とする窒素酸化物の除去
装置。1. A first catalyst layer having at least one of platinum and palladium provided in a preceding stage of a flow path of a gas containing nitrogen oxide, and an AB ′ provided in a latter stage of the first catalyst layer. 1-x C'x O 3
(A is at least one of lanthanum, strontium, cerium, barium, and calcium, B'is at least one of cobalt, iron, nickel, chromium, manganese, and magnesium, and C'is at least one of platinum and palladium. On the other hand, x is 0.005 ≦ x ≦ 0.2), and a nitrogen oxide removing apparatus comprising a second catalyst layer having a substance having a perovskite structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5120520A JPH06304449A (en) | 1993-04-23 | 1993-04-23 | Apparatus for removing nitrogen oxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5120520A JPH06304449A (en) | 1993-04-23 | 1993-04-23 | Apparatus for removing nitrogen oxide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06304449A true JPH06304449A (en) | 1994-11-01 |
Family
ID=14788289
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5120520A Pending JPH06304449A (en) | 1993-04-23 | 1993-04-23 | Apparatus for removing nitrogen oxide |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06304449A (en) |
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