JP2003200061A - Exhaust gas purifying catalyst and exhaust gas purifying device - Google Patents
Exhaust gas purifying catalyst and exhaust gas purifying deviceInfo
- Publication number
- JP2003200061A JP2003200061A JP2002234811A JP2002234811A JP2003200061A JP 2003200061 A JP2003200061 A JP 2003200061A JP 2002234811 A JP2002234811 A JP 2002234811A JP 2002234811 A JP2002234811 A JP 2002234811A JP 2003200061 A JP2003200061 A JP 2003200061A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- exhaust gas
- gas purifying
- layer
- purifying catalyst
- 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
- 239000003054 catalyst Substances 0.000 title claims abstract description 221
- 239000007789 gas Substances 0.000 claims abstract description 92
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 59
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 36
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 29
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000000446 fuel Substances 0.000 claims abstract description 10
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 7
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 7
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims abstract description 7
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 22
- 239000010948 rhodium Substances 0.000 claims description 18
- 239000002245 particle Substances 0.000 claims description 9
- 239000010970 precious metal Substances 0.000 claims description 8
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 6
- 239000011734 sodium Substances 0.000 claims description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 239000011777 magnesium Substances 0.000 claims description 4
- 229910052697 platinum Inorganic materials 0.000 claims description 4
- 229910052703 rhodium Inorganic materials 0.000 claims description 4
- 229910052684 Cerium Inorganic materials 0.000 claims description 3
- 229910052788 barium Inorganic materials 0.000 claims description 3
- 229910052792 caesium Inorganic materials 0.000 claims description 3
- 239000011575 calcium Substances 0.000 claims description 3
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 2
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 229910052700 potassium Inorganic materials 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- 229910052712 strontium Inorganic materials 0.000 claims description 2
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 15
- 239000001301 oxygen Substances 0.000 abstract description 15
- 229910052760 oxygen Inorganic materials 0.000 abstract description 15
- 239000010410 layer Substances 0.000 description 86
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 77
- 210000004027 cell Anatomy 0.000 description 38
- 239000000843 powder Substances 0.000 description 36
- 239000002002 slurry Substances 0.000 description 31
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 23
- 229910002091 carbon monoxide Inorganic materials 0.000 description 23
- 230000000694 effects Effects 0.000 description 17
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 13
- 229910017604 nitric acid Inorganic materials 0.000 description 13
- 238000000746 purification Methods 0.000 description 13
- 239000007864 aqueous solution Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 12
- 239000007788 liquid Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 10
- 238000001179 sorption measurement Methods 0.000 description 10
- 239000000243 solution Substances 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 8
- 229910001593 boehmite Inorganic materials 0.000 description 7
- 238000000227 grinding Methods 0.000 description 7
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 229910001868 water Inorganic materials 0.000 description 7
- 230000009471 action Effects 0.000 description 6
- 229910052878 cordierite Inorganic materials 0.000 description 6
- 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 6
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 229910052746 lanthanum Inorganic materials 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000008719 thickening Effects 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 101100321669 Fagopyrum esculentum FA02 gene Proteins 0.000 description 1
- 101000741917 Homo sapiens Serine/threonine-protein phosphatase 1 regulatory subunit 10 Proteins 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 102100038743 Serine/threonine-protein phosphatase 1 regulatory subunit 10 Human genes 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- ITHZDDVSAWDQPZ-UHFFFAOYSA-L barium acetate Chemical compound [Ba+2].CC([O-])=O.CC([O-])=O ITHZDDVSAWDQPZ-UHFFFAOYSA-L 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- VGBWDOLBWVJTRZ-UHFFFAOYSA-K cerium(3+);triacetate Chemical compound [Ce+3].CC([O-])=O.CC([O-])=O.CC([O-])=O VGBWDOLBWVJTRZ-UHFFFAOYSA-K 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- -1 rare earth compound Chemical class 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、排ガス浄化触媒及
び排ガス浄化装置に係り、更に詳細には、自動車（ガソ
リン、ディーゼル）及びボイラーなどの内燃機関から排
出される排ガス中の有害成分である炭化水素（ＨＣ）、
一酸化炭素（ＣＯ）及び窒素酸化物（ＮＯｘ）を浄化す
る排ガス浄化触媒及び排ガス浄化装置に関するものであ
る。また、本発明の排ガス浄化触媒は、特に酸素過剰領
域（リーン時）のＮＯｘ浄化に着目してなされたもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying catalyst and an exhaust gas purifying apparatus, and more particularly to carbonization which is a harmful component in exhaust gas discharged from internal combustion engines such as automobiles (gasoline, diesel) and boilers. Hydrogen (HC),
The present invention relates to an exhaust gas purification catalyst and an exhaust gas purification device that purify carbon monoxide (CO) and nitrogen oxides (NOx). Further, the exhaust gas purifying catalyst of the present invention is made with a particular focus on NOx purification in the oxygen excess region (when lean).
【０００２】[0002]
【従来の技術】従来より自動車の排ガス浄化用触媒とし
て、理論空燃比（ストイキ）において排ガス中のＣＯ及
びＨＣの酸化とＮＯｘの還元とを同時に行なって浄化す
る三元触媒が用いられている。このような三元触媒とし
ては、例えばコーディエライトなどからなる耐熱性基材
にγ−アルミナからなる多孔質担体層を形成し、その多
孔質担体層に、パラジウム（Ｐｄ）、白金（Ｐｔ）及び
ロジウム（Ｒｈ）などの貴金属を担持させたものが広く
知られている。2. Description of the Related Art Conventionally, as a catalyst for purifying exhaust gas of automobiles, a three-way catalyst has been used which purifies by simultaneously oxidizing CO and HC and reducing NOx in exhaust gas at a stoichiometric air-fuel ratio. As such a three-way catalyst, for example, a porous carrier layer made of γ-alumina is formed on a heat resistant substrate made of cordierite, and palladium (Pd), platinum (Pt) is formed on the porous carrier layer. It is widely known that noble metals such as rhodium (Rh) and the like are supported.
【０００３】また、近年、地球環境保護の観点から、自
動車などの内燃機関から排出される排ガス中の二酸化炭
素（ＣＯ２）が問題とされ、その解決策として酸素過剰
のリーン雰囲気において希薄燃焼させる、いわゆるリー
ンバーンが有望視されている。このリーンバーンにおい
ては、燃費の向上によりＣＯ２の排出量を低減すること
ができる。In recent years, from the viewpoint of protecting the global environment, carbon dioxide (CO 2 ) in exhaust gas discharged from internal combustion engines such as automobiles has become a problem, and as a solution to this problem, lean combustion is performed in a lean atmosphere with excess oxygen. The so-called lean burn is promising. In this lean burn, CO 2 emissions can be reduced by improving fuel efficiency.
【０００４】希薄燃焼自動車においては、リーンバーン
エンジンからの排ガス中に三元触媒を配置し、三元触媒
は主として酸化触媒として機能し、排ガス中のＣＯ及び
ＨＣを酸化して浄化することができる。また、雰囲気が
リーン〜ストイキ〜リッチと変動する場合に用いれば、
リーン雰囲気では主として酸化触媒として機能し、スト
イキ〜リッチ雰囲気では還元触媒としても機能して排ガ
ス中のＣＯ及びＨＣによってＮＯｘを還元して浄化する
ことができる。しかし、希薄燃焼走行時、排ガス雰囲気
が理論空燃状態に比べ酸素過剰雰囲気（リーン）となる
が、リーン域で通常の三元触媒を適用させた場合、過剰
な酸素の影響からＮＯｘ浄化作用が不十分となることが
あった。このため、酸素が過剰となってもＮＯｘを浄化
できる触媒の開発が望まれていた。In a lean-burn automobile, a three-way catalyst is arranged in the exhaust gas from the lean burn engine, and the three-way catalyst mainly functions as an oxidation catalyst and can oxidize and purify CO and HC in the exhaust gas. . Also, if it is used when the atmosphere changes from lean to stoichi to rich,
It mainly functions as an oxidation catalyst in the lean atmosphere, and also functions as a reduction catalyst in the stoichiometric-rich atmosphere to reduce and purify NOx by CO and HC in the exhaust gas. However, during lean burn running, the exhaust gas atmosphere becomes an oxygen excess atmosphere (lean) compared to the stoichiometric air-fuel state, but when a normal three-way catalyst is applied in the lean region, the NOx purification action is due to the effect of excess oxygen. It was sometimes insufficient. Therefore, it has been desired to develop a catalyst that can purify NOx even if oxygen becomes excessive.
【０００５】ところで、三元触媒において触媒作用を発
現するのは担持されている貴金属であるが、貴金属の触
媒作用が発現する温度域は比較的高温域にあるために、
低温域に有害成分を浄化しにくいという問題がある。そ
のために冬季や始動時などの排ガスが低温域にある場合
には、浄化活性が低いという不具合があった。例えば白
金（Ｐｔ）とランタン（Ｌａ）を多孔質担体に担持した
触媒（特開平５−１６８８６０号公報）に代表されるよ
うに、リーン域でＮＯｘを吸蔵し、ストイキ〜リッチ域
でＮＯｘを放出させ浄化する触媒などが提案されてい
る。しかし、これら触媒では、優れたＮＯｘ浄化性能を
発揮させることが困難であった。By the way, it is the supported noble metal that exhibits the catalytic action in the three-way catalyst, but the temperature range in which the catalytic action of the noble metal appears is relatively high.
There is a problem that it is difficult to purify harmful components in the low temperature range. Therefore, when exhaust gas is in a low temperature range such as in winter or at the time of starting, there is a problem that the purification activity is low. For example, as represented by a catalyst in which platinum (Pt) and lanthanum (La) are supported on a porous carrier (Japanese Patent Laid-Open No. 5-168860), NOx is stored in the lean range and NOx is released in the stoichiometric to rich range. A catalyst and the like for purifying it have been proposed. However, it has been difficult for these catalysts to exhibit excellent NOx purification performance.
【０００６】そこで、三元触媒をエンジン直下に配置し
て、昇温し易くすることが行われている。また、排ガス
が流入する上流部に貴金属を高密度で担持することも行
われている。このように、上流部に貴金属を高密度で担
持することにより、上流部において貴金属と排ガスとが
接触する確率が高まり、ＣＯ及びＨＣの酸化反応が起き
る確率が高まる。そして、一旦酸化反応が起きると、そ
の着火が伝播して酸化反応がさらに進行する。また、酸
化反応は発熱反応であるため、その反応熱によって三元
触媒が加熱されて昇温し、貴金属の活性温度域まで速や
かに昇温されるという作用もある。従って、上流部に貴
金属を高密度で担持し低温域における浄化活性の向上が
狙える。例えば、特開２００１−１６２１６６号公報で
は、フロント部にＰｄを含有させコート層を薄くし熱容
量を軽くすることが開示されている。コールドスタート
条件でのＨＣ、ＣＯをよりはやく浄化するという点では
有用である。Therefore, a three-way catalyst is arranged immediately below the engine to facilitate temperature rise. In addition, it is also carried out to support the noble metal at a high density on the upstream side where the exhaust gas flows. As described above, by loading the noble metal at a high density on the upstream portion, the probability that the noble metal and the exhaust gas come into contact with each other at the upstream portion increases, and the probability that the oxidation reaction of CO and HC occurs. Then, once the oxidation reaction occurs, the ignition is propagated and the oxidation reaction further progresses. Further, since the oxidation reaction is an exothermic reaction, the heat of the reaction heats the three-way catalyst to raise the temperature, which has the effect of rapidly raising the temperature to the activation temperature range of the noble metal. Therefore, it is possible to support the noble metal at a high density in the upstream portion and improve the purification activity in the low temperature range. For example, Japanese Patent Application Laid-Open No. 2001-162166 discloses that Pd is contained in the front part to make the coat layer thin and reduce the heat capacity. It is useful in that HC and CO under cold start conditions are purified more quickly.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、Ｐｄの
ようなＨＣ、ＣＯの酸化性能に優れる貴金属を用いる場
合、ホット性能に悪影響がでる。具体的にはホット時の
高速条件、例えば、１０・１５モードの１５モードで
は、フロントの触媒でＨＣ、ＣＯなどの還元剤を消費し
ないため、リヤの触媒でＮＯｘを還元できるが、ホット
時においてもアイドル条件では、フロントの触媒によっ
てＨＣ、ＣＯがすばやくなくなってしまい、リヤ側の触
媒においてＮＯｘの還元ができないという問題点があっ
た。However, when a precious metal such as Pd having excellent HC and CO oxidation performance is used, the hot performance is adversely affected. Specifically, in high-speed conditions at the time of hot, for example, 15 mode of 10.15 mode, since the reducing catalyst such as HC and CO is not consumed by the front catalyst, NOx can be reduced by the rear catalyst, but at the time of hot. However, under idle conditions, there is a problem in that HC and CO are quickly lost by the front catalyst, and NOx cannot be reduced by the rear catalyst.
【０００８】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、その目的とするところ
は、酸素が過剰となっても優れたＮＯｘ浄化性能を発揮
でき、またコールド時のＨＣ、ＣＯ性能を保持しつつ、
ホット時にＨＣ、ＣＯが少ない条件下でもＮＯｘ性能を
両立できる排ガス浄化触媒及び排ガス浄化装置を提供す
ることにある。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 exhibit excellent NOx purification performance even when oxygen is excessive, and for cold use. While maintaining the HC and CO performance of
An object of the present invention is to provide an exhaust gas purifying catalyst and an exhaust gas purifying apparatus that can achieve both NOx performance even under conditions where HC and CO are small when hot.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、上記課題
を解決するため鋭意検討を重ねた結果、触媒成分を所定
の面積割合で担体に担持することにより、上記課題が解
決されることを見出し、本発明を完成するに至った。Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems, and as a result, the above problems can be solved by supporting a catalyst component on a carrier at a predetermined area ratio. The present invention has been completed and the present invention has been completed.
【００１０】[0010]
【発明の実施の形態】以下、本発明の排ガス浄化触媒に
ついて詳細に説明する。なお、本明細書において「％」
は、特記しない限り質量百分割合を示す。BEST MODE FOR CARRYING OUT THE INVENTION The exhaust gas purifying catalyst of the present invention will be described in detail below. In this specification, "%"
Indicates mass percentage unless otherwise specified.
【００１１】まず、本発明の第１の排ガス浄化触媒は、
モノリス担体上に、貴金属及びアルミナを含む触媒成分
が担持されて成る。また、上記触媒成分は、次の式１
２０％＜単位セルピッチ当たりの触媒層の面積割合＜３５％ …（１）
で表される触媒層を形成する。これは、本発明者らが、
単位セルピッチ当たりの触媒層面積の割合を高くするこ
と、言い換えれば触媒層を厚くすることにより、ＨＣ、
ＣＯなどの還元剤が少ない条件でもＮＯｘとの反応性が
向上することを見出したことによる。従って、触媒層が
厚いほどガスの滞留時間を長期化でき、その結果高いＮ
Ｏｘ反応活性が得られる。一方、触媒層の面積割合が２
０％以下であると、触媒層が薄いことからガス滞留時間
が十分に得られず、ＮＯｘと還元剤との反応性が不足す
る。３５％以上ではガス流路が狭くなり、排圧が上昇し
てエンジン出力の低下を引き起こすという不都合が生じ
る。なお、上記「単位セルピッチ」とは、図１に示すよ
うに、ハニカム担体などを構成する複数のセルの１つで
あって、セル壁の中心を結んだものを示す。First, the first exhaust gas purifying catalyst of the present invention is
A catalyst component containing a noble metal and alumina is supported on a monolith carrier. The catalyst component forms a catalyst layer represented by the following formula 1 20% <area ratio of catalyst layer per unit cell pitch <35% (1). This is because the inventors
By increasing the ratio of the catalyst layer area per unit cell pitch, in other words, by thickening the catalyst layer, HC,
This is because it was found that the reactivity with NOx is improved even under the condition that the reducing agent such as CO is small. Therefore, the thicker the catalyst layer, the longer the gas residence time can be, resulting in a higher N
Ox reaction activity is obtained. On the other hand, the area ratio of the catalyst layer is 2
If it is 0% or less, the gas retention time cannot be sufficiently obtained because the catalyst layer is thin, and the reactivity between NOx and the reducing agent becomes insufficient. If it is 35% or more, the gas flow passage becomes narrow, and the exhaust pressure rises, causing a problem of lowering the engine output. The above-mentioned "unit cell pitch" means one of a plurality of cells constituting a honeycomb carrier or the like, and connecting the centers of cell walls, as shown in Fig. 1.
【００１２】また、上記触媒成分は積層体を形成し、そ
の最下層が貴金属を含まず且つアルミナを主成分とし、
また、これ以外の少なくとも１層が貴金属を含有して成
ることが好適である。貴金属を含まない層を最下層とす
ることで、貴金属を含有する層がより表層に近くなり、
ＮＯｘとＨＣ、ＣＯなどの還元剤との反応効率が向上し
易くなると考えられるためである。更に、該最下層の密
度は１００〜３００ｇ／Ｌであることが好適である。ま
た、より好ましくは１１０〜２５０ｇ／Ｌ、特に好まし
くは１２０〜２１０ｇ／Ｌであることがよい。最下層の
密度が１００ｇ／Ｌ未満では、上記面積割合の触媒層を
得るに当たり、最下層に積層する貴金属含有層が厚くな
ってしまい、貴金属含有層が表層側に集中せず反応効率
が低下し易い。３００ｇ／Ｌ超では上記面積割合の触媒
層の限界であり、貴金属含有層が塗布しにくい。Further, the above catalyst component forms a laminated body, and the lowermost layer thereof contains no precious metal and contains alumina as a main component,
In addition, it is preferable that at least one layer other than this contains a noble metal. By making the layer containing no precious metal the lowest layer, the layer containing the precious metal becomes closer to the surface layer,
This is because the reaction efficiency between NOx and a reducing agent such as HC or CO is likely to be improved. Further, the density of the lowermost layer is preferably 100 to 300 g / L. Further, it is more preferably 110 to 250 g / L, and particularly preferably 120 to 210 g / L. When the density of the lowermost layer is less than 100 g / L, in obtaining the catalyst layer having the above area ratio, the noble metal-containing layer laminated on the lowermost layer becomes thick, the noble metal-containing layer is not concentrated on the surface layer side, and the reaction efficiency decreases. easy. If it exceeds 300 g / L, the catalyst layer has a limit of the above area ratio, and it is difficult to apply the noble metal-containing layer.
【００１３】また、上記最下層は、該最下層の質量に対
しＣｅＯ２換算で１〜２０％の割合でセリウムを更に含
有して成ることが好適である。また、より好ましくは３
〜１５％、特に好ましくは５〜１０％であることがよ
い。Ｃｅを貴金属含有層以外の層に含有することで、高
温時（１５モードなど）の雰囲気変動に対しても、高い
ＮＯｘ、ＨＣ浄化性能を発揮できる。Ｃｅ含有量が１％
未満ではＣｅがもつ酸素ストレージ能力において、酸素
放出量がすくなく、ＨＣ、ＮＯｘ転化性能は低くなり易
く、２０％超ではＣｅがもつ酸素ストレージ能力におい
て、酸素放出量が多すぎて、ＨＣとの反応が優先し、Ｎ
Ｏｘの転化性能が低下しやすい。It is preferable that the lowermost layer further contains cerium at a ratio of 1 to 20% in terms of CeO 2 with respect to the mass of the lowermost layer. Also, more preferably 3
˜15%, particularly preferably 5 to 10%. By containing Ce in a layer other than the noble metal-containing layer, high NOx and HC purification performance can be exhibited even with respect to changes in the atmosphere at high temperatures (15 modes, etc.). Ce content is 1%
If the amount is less than less than 50%, the amount of released oxygen is small in the oxygen storage capacity of Ce, and the HC and NOx conversion performance tends to be low. If it exceeds 20%, the amount of released oxygen is too large in the oxygen storage capacity of Ce to react with HC. Has priority, N
The conversion performance of Ox tends to decrease.
【００１４】更に、上述の排ガス浄化触媒の上流側にパ
ラジウム（Ｐｄ）を含有する触媒（以下「上流側触媒」
と略す）を配設することにより、本発明の排ガス浄化装
置が得られる。この場合、下流側に位置する排ガス浄化
触媒（以下「下流側触媒」と略す）は、ＨＣ、ＣＯなど
の還元剤が少なくても、ＮＯｘとの反応選択性の高い特
性を有するので、アイドル時などの流速が遅い条件にお
いて、この触媒の上流側にＰｄなどのＨＣ、ＣＯの酸化
能が高いものを配置した場合には、下流側触媒にとって
不利な条件となっても、優れた排ガス浄化能を発揮しう
る。これによって、コールド性能（例えば１１モード）
とホット性能（例えば１０・１５モード）の両立を図る
ことが可能となる。Further, a catalyst containing palladium (Pd) on the upstream side of the above exhaust gas purifying catalyst (hereinafter referred to as "upstream catalyst").
Is abbreviated), the exhaust gas purifying apparatus of the present invention can be obtained. In this case, the exhaust gas purifying catalyst located on the downstream side (hereinafter abbreviated as “downstream side catalyst”) has characteristics of high reaction selectivity with NOx even when the reducing agents such as HC and CO are small, and therefore, at the time of idling. When a catalyst having a high HC and CO oxidizing ability such as Pd is arranged on the upstream side of this catalyst under the condition that the flow velocity is slow, the exhaust gas purifying ability is excellent even if it is a disadvantageous condition for the downstream catalyst. Can be demonstrated. This allows cold performance (eg 11 modes)
It is possible to achieve both hot performance and hot performance (for example, 10/15 mode).
【００１５】更にまた、下流側触媒の触媒層の単位セル
ピッチ当たりの面積割合は、上流側触媒の該面積割合よ
り大きいことが好適である。単位セルピッチ当たりの面
積割合が大きいほど触媒使用量が大きいが、下流側触媒
の面積割合を大きくすることでエンジン出口から下流側
触媒までの間で排気の圧力が増大し、上流側触媒近傍の
温度上昇が早まるため、ＨＣ、ＣＯ酸化能力が向上する
と考えられる。即ち、上流側触媒の使用量を増やすこと
なく上流側触媒への排ガス温度を上昇させうるので有効
である。なお、下流側触媒の面積割合が上流側触媒の面
積割合より小さいときは、排気の圧力は上流側触媒のコ
ート厚で決まってしまう。しかし、上流側触媒のコート
厚を大きくするには触媒使用量を増やさねばならず、熱
容量が大きくなるので好ましくない。Furthermore, it is preferable that the area ratio of the catalyst layer of the downstream catalyst per unit cell pitch is larger than the area ratio of the upstream catalyst. The larger the area ratio per unit cell pitch, the greater the amount of catalyst used.However, by increasing the area ratio of the downstream catalyst, the exhaust pressure increases from the engine outlet to the downstream catalyst, and the temperature near the upstream catalyst increases. It is considered that the oxidization ability of HC and CO is improved because the increase is quick. That is, it is effective because the exhaust gas temperature to the upstream catalyst can be raised without increasing the amount of the upstream catalyst used. When the area ratio of the downstream side catalyst is smaller than the area ratio of the upstream side catalyst, the exhaust pressure is determined by the coat thickness of the upstream side catalyst. However, in order to increase the coat thickness of the upstream side catalyst, the amount of catalyst used must be increased and the heat capacity becomes large, which is not preferable.
【００１６】次に、本発明の第２の排ガス浄化触媒は、
触媒成分が次の式２
２０％＜単位セルピッチ当たりの触媒層の面積割合＜３５％ …（２）
で表される触媒層を形成して成る。このように、単位セ
ルピッチ当たりの触媒層面積の割合を高くすること、言
い換えれば触媒層を厚くすることにより、空燃比が理論
空燃比よりリーン域のときにＮＯｘを吸着する能力が向
上し、ストイキ〜リッチ域のときに吸着したＮＯｘを窒
素に還元する。これは、ＮＯｘの吸着反応が比較的速度
の遅い反応であることに着目したものであり、かかる構
成とすることで触媒層におけるガスの滞留時間を長期化
でき、その結果高いＮＯｘ吸着活性が得られる。また、
この効果は、触媒温度が高い状況（５００℃程度）で特
に大きくなる。ＮＯｘ吸着作用は本来４００℃を超える
高温で大幅に低下するが、本発明では高温によるＮＯｘ
吸着作用の低下がガスの滞留時間の増大により補われ
る。一方、触媒層の面積割合が２０％以下であると、触
媒層が薄いことからガス滞留時間が十分に得られず、Ｎ
Ｏｘの吸着機能が不足し、３５％を超えるとガス流路が
狭くなり、排圧が上昇してエンジン出力の低下を引き起
こすという不都合が生じる。Next, the second exhaust gas purifying catalyst of the present invention is
A catalyst component is formed by forming a catalyst layer represented by the following formula 2 20% <area ratio of catalyst layer per unit cell pitch <35% (2). In this way, by increasing the ratio of the catalyst layer area per unit cell pitch, in other words, by thickening the catalyst layer, the ability to adsorb NOx is improved when the air-fuel ratio is in the lean range than the stoichiometric air-fuel ratio, and stoichiometry is improved. ~ Reduces NOx adsorbed in the rich region to nitrogen. This is focused on the fact that the NOx adsorption reaction is a reaction with a relatively slow rate. With such a configuration, the residence time of the gas in the catalyst layer can be lengthened, and as a result, high NOx adsorption activity can be obtained. To be Also,
This effect becomes particularly large when the catalyst temperature is high (about 500 ° C.). Originally, the NOx adsorbing action is significantly reduced at a high temperature exceeding 400 ° C.
The reduced adsorption effect is compensated by the increased residence time of the gas. On the other hand, when the area ratio of the catalyst layer is 20% or less, the gas retention time cannot be sufficiently obtained because the catalyst layer is thin, and N
If the Ox adsorption function is insufficient and exceeds 35%, the gas flow path becomes narrow, and the exhaust pressure rises, causing a decrease in engine output.
【００１７】また、上記排ガス浄化触媒は、排ガスを排
出する内燃機関等がリーン域とストイキ〜リッチ域とを
繰り返して運転されることで、高いＮＯｘ浄化作用を発
揮する。具体的には、空燃比の範囲がストイキ〜リッチ
域で１０〜１４．７、リーン域で１８〜５０であること
が望ましい。なお、ストイキ〜リッチ域が１０未満であ
ると還元性ガス（ＨＣ、ＣＯなど）が過剰となり、触媒
中の貴金属が被覆され活性低下を引き起こすことがあ
る。一方、１４．７を超えると還元性ガスが不足しＮＯ
ｘの脱離及び浄化作用が十分に得られない。また、リー
ン域が１８未満であるとＮＯｘ吸着に必要な酸素が不足
しＮＯｘ吸着作用が不十分となることがある。一方、５
０を超えるとＮＯｘ吸着に必要な酸素量は既に飽和状態
となり、有意な効果は得られ難い。Further, the exhaust gas purifying catalyst exhibits a high NOx purifying action when the internal combustion engine or the like for exhausting the exhaust gas is repeatedly operated in the lean region and the stoichiometric-rich region. Specifically, it is desirable that the range of the air-fuel ratio is 10 to 14.7 in the stoichiometric region to the rich region and 18 to 50 in the lean region. If the stoichiometric-rich region is less than 10, the reducing gas (HC, CO, etc.) becomes excessive, and the noble metal in the catalyst may be coated to cause a decrease in activity. On the other hand, if it exceeds 14.7, the reducing gas is insufficient and NO
The desorption and purification action of x cannot be sufficiently obtained. Further, if the lean region is less than 18, the oxygen required for NOx adsorption may be insufficient and the NOx adsorption action may become insufficient. Meanwhile, 5
When it exceeds 0, the amount of oxygen required for NOx adsorption is already saturated, and it is difficult to obtain a significant effect.
【００１８】なお、セル角の最厚部及び平坦部の最薄部
とは、例えば、図２に示すような部分をいう。The thickest part of the cell angle and the thinnest part of the flat part are, for example, the parts as shown in FIG.
【００１９】更にまた、上記排ガス浄化触媒を自動車に
設置する場合には、上記触媒層の総重量を４００〜６０
０ｇとすることが好ましい。この場合、４００ｇ未満で
は触媒層の厚さが所望の厚さとなりにくく、６００ｇを
超えるとガス流路が狭くなりエンジン出力の低下を引き
起こす可能性がある。Furthermore, when the exhaust gas purifying catalyst is installed in an automobile, the total weight of the catalyst layer is 400 to 60.
It is preferably 0 g. In this case, if it is less than 400 g, the thickness of the catalyst layer is difficult to reach a desired thickness, and if it exceeds 600 g, the gas flow passage becomes narrow, which may cause a reduction in engine output.
【００２０】また、上記排ガス浄化触媒は、モノリス担
体上に、貴金属と、アルカリ金属及び／又はアルカリ土
類金属と、アルミナと、を含む触媒成分が担持されて成
る。かかる貴金属は、触媒容量１Ｌ当たり０．５〜１０
ｇの割合で含有されることが性能とコストの両立の面か
ら好適である。含有量が０．５ｇ以上で貴金属活性が高
く上述の効果が十分発揮され、１０ｇ以下であると貴金
属の触媒反応速度よりも排ガスの拡散速度が律速となる
ことはなく、増量による有意な効果が得られる。一方、
上記アルカリ金属及び／又はアルカリ土類金属は、触媒
容量１Ｌ当たり５〜８０ｇの割合で含有されることが性
能の面から好適である。含有量が５ｇ以上であればより
ＮＯｘ吸着サイトが不足することなく上述の効果が発現
し、８０ｇ以下であると触媒層内のガス経路が閉塞し性
能が低下することがない。Further, the exhaust gas purifying catalyst comprises a monolith carrier on which a catalyst component containing a noble metal, an alkali metal and / or an alkaline earth metal, and alumina is supported. The amount of such precious metal is 0.5 to 10 per 1 L of catalyst capacity.
It is preferable that the content is g in terms of both performance and cost. When the content is 0.5 g or more, the noble metal activity is high and the above-mentioned effects are sufficiently exhibited, and when the content is 10 g or less, the diffusion rate of exhaust gas is not rate-controlling than the catalytic reaction rate of the noble metal, and a significant effect by the increase in amount is obtained. can get. on the other hand,
From the viewpoint of performance, it is preferable that the above-mentioned alkali metal and / or alkaline earth metal is contained in a ratio of 5 to 80 g per 1 L of the catalyst volume. If the content is 5 g or more, the above-mentioned effect is exhibited without further shortage of NOx adsorption sites, and if it is 80 g or less, the gas passage in the catalyst layer is not blocked and the performance does not deteriorate.
【００２１】上記貴金属としては、白金（Ｐｔ）、ロジ
ウム（Ｒｈ）又はパラジウム（Ｐｄ）、及びこれらの任
意の組合せに係るものが好適である。これらはストイキ
時に三元触媒としての機能を有するので有効である。ま
た、上記アルカリ金属及び／又はアルカリ土類金属とし
ては、マグネシウム（Ｍｇ）、カルシウム（Ｃａ）、ス
トロンチウム（Ｓｒ）、バリウム（Ｂａ）、ナトリウム
（Ｎａ）、カリウム（Ｋ）又はセシウム（Ｃｓ）、及び
これらの任意の組合せに係るものが好適である。これら
はＮＯｘ吸着機能が高いので有効である。また、上記Ｂ
ａ、Ｍｇ、Ｎａ及びＣｓは、炭酸塩、酸化物及び水酸化
物などの形態で使用することができる。As the above-mentioned noble metal, platinum (Pt), rhodium (Rh) or palladium (Pd), and any combination thereof are preferable. These are effective because they function as a three-way catalyst during stoichiometry. Further, as the alkali metal and / or alkaline earth metal, magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), sodium (Na), potassium (K) or cesium (Cs), And those relating to any combination thereof are preferred. These are effective because they have a high NOx adsorption function. Also, the above B
The a, Mg, Na and Cs can be used in the form of carbonate, oxide and hydroxide.
【００２２】また、上記アルミナは、上記触媒層の総重
量に対して７０〜９５％の割合で含有されることが好ま
しい。アルミナは多孔性であることから、ガスの滞留時
間を長期化できるので有効である。７０％以上で細孔容
積が不足し十分なガス滞留時間が得られ、９５％以下で
あるとガス滞留時間を長期化する効果が飽和点に達する
ことなく効果が得られやすい。更に、上記アルミナの平
均粒径（メディアン径）は、１〜４μｍであることが好
適である。通常、触媒担体（ハニカム耐火性無機担体な
ど）にアルミナを大量に担持しようとするとセル内に詰
まりが発生することがある。本発明では、アルミナの粒
径を微粒化することで触媒層に所望量を使用することが
可能となる。このような粒径とするには、例えばアルミ
ナ粉末を含む湿式スラリを製造する際の粉砕を十分に行
うことができる。粉砕装置は特に限定されず、市販のボ
ール式振動見るなどを使用できる。このとき、粉砕を十
分にするには、ボール径を小さくすること、粉砕時間を
長くすること、及び振幅・振動周波数を調整すること、
などを行えばよい。なお、粒径は、例えばレーザー回折
式粒度分布測定装置により測定することができ、その粒
度分布をメディアン分布に従って整理し平均粒径を求め
ることができる。更にまた、上記アルミナの比表面積
は、１００〜３００ｍ２／ｇであることが好ましい。触
媒層の増大に加えて、このような高比表面積のアルミナ
を用いることで、ガスの滞留時間を更に長期化すること
ができる。The alumina is preferably contained in a proportion of 70 to 95% with respect to the total weight of the catalyst layer. Since alumina is porous, it is effective because it can prolong the residence time of gas. If it is 70% or more, the pore volume is insufficient and a sufficient gas retention time is obtained, and if it is 95% or less, the effect of prolonging the gas retention time does not reach the saturation point, and the effect is easily obtained. Further, the average particle size (median size) of the alumina is preferably 1 to 4 μm. Usually, when a large amount of alumina is loaded on a catalyst carrier (such as a honeycomb refractory inorganic carrier), clogging may occur in the cells. In the present invention, it is possible to use a desired amount in the catalyst layer by making the particle size of alumina finer. In order to obtain such a particle size, for example, pulverization when producing a wet slurry containing alumina powder can be sufficiently performed. The crushing device is not particularly limited, and a commercially available ball-type vibration watch or the like can be used. At this time, in order to sufficiently crush, decrease the ball diameter, lengthen the crushing time, and adjust the amplitude and vibration frequency,
And so on. The particle size can be measured, for example, by a laser diffraction type particle size distribution measuring device, and the average particle size can be determined by organizing the particle size distribution according to the median distribution. Furthermore, the specific surface area of the alumina is preferably 100 to 300 m 2 / g. By using such a high specific surface area alumina in addition to the increase in the catalyst layer, the residence time of the gas can be further prolonged.
【００２３】また、上記貴金属は、多孔質体に担持され
ていることが望ましく、特に上記アルミナに担持されて
いることがよい。かかるアルミナは耐熱性が高いことが
望ましく、従来から三元触媒で適用されているように、
セリウム（Ｃｅ）、ランタン（Ｌａ）等の希土類化合物
やジルコニウム（Ｚｒ）などの添加物を更に加えること
もできる。更に、三元触媒としての機能を増強させるた
めに、従来から三元触媒に用いられている材料、具体的
には酸素ストレージ機能を有するセリア、貴金属へのＨ
Ｃ吸着被毒を緩和するＢａ、及びＲｈの耐熱性向上に寄
与するジルコニアなどを適宜加えることもできる。な
お、本排ガス浄化触媒は、その作用が妨げられる量でな
ければ、上記構成成分とともに不純物を含んでいても構
わないことは言うまでもない。例えば、Ｂａ中に含まれ
るＳｒ、Ｃｅ中に含まれるＬａ、ネオジウム（Ｎｄ）及
びサマリウム（Ｓｍ）、Ｚｒ中に含まれるハフニウム
（Ｈｆ）及び硫黄（Ｓ）などは、微量であれば構わな
い。The above-mentioned noble metal is preferably supported on a porous body, and particularly preferably supported on the above-mentioned alumina. It is desirable that such alumina has high heat resistance, and as conventionally applied to a three-way catalyst,
A rare earth compound such as cerium (Ce) or lanthanum (La) or an additive such as zirconium (Zr) can be further added. Furthermore, in order to enhance the function as a three-way catalyst, materials conventionally used for three-way catalysts, specifically, ceria having an oxygen storage function and H for noble metals.
It is also possible to appropriately add Ba, which alleviates the C adsorption poisoning, and zirconia, which contributes to the improvement of the heat resistance of Rh. It is needless to say that the exhaust gas purifying catalyst may contain impurities together with the above-mentioned constituent components as long as the action thereof is not hindered. For example, Sr contained in Ba, La contained in Ce, neodymium (Nd) and samarium (Sm), and hafnium (Hf) and sulfur (S) contained in Zr may be in a small amount.
【００２４】なお、本発明の排ガス浄化触媒は各種形状
で使用でき、例えばコーディエライトなどのセラミック
スやフェライト系ステンレス等の金属で構成される一体
構造型のハニカム状担体に触媒成分を担持させて使用で
きる。このとき、触媒成分を多数の触媒層として被覆す
ることもできる。The exhaust gas purifying catalyst of the present invention can be used in various shapes. For example, a catalyst component is supported on an integrally structured honeycomb carrier composed of a ceramic such as cordierite or a metal such as ferritic stainless steel. Can be used. At this time, the catalyst component may be coated as many catalyst layers.
【００２５】[0025]
【実施例】以下、本発明を実施例及び比較例により更に
詳細に説明するが、本発明はこれら実施例に限定される
ものではない。なお、実施例及び比較例における全ての
実験はガソリン車で行ったが、ディーゼル車でも同様の
効果が得られることは言うまでもない。EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, although all the experiments in the examples and the comparative examples were performed in a gasoline vehicle, it goes without saying that the same effect can be obtained in a diesel vehicle.
【００２６】以下に示す実施例１〜３及び比較例１では
排ガス浄化装置を作製し、実施例４〜８及び比較例２で
は排ガス浄化触媒を作製した。Exhaust gas purifying devices were produced in Examples 1 to 3 and Comparative Example 1, and exhaust gas purifying catalysts were produced in Examples 4 to 8 and Comparative Example 2.
【００２７】（実施例１）
（１）下流側触媒の準備
第１層（最下層）の形成
活性アルミナ粉末とベーマイトアルミナ及び硝酸をポッ
ト容器に入れ、ボールミルにて１ｈｒ粉砕した。この内
層スラリー液をコージェライト質モノリス担体（０．９
４Ｌ、２ミル ９００ セル／平方インチ）に塗布し、
空気流にてセル内の余剰のスラリーを除去・乾燥し、４
００℃で１時間焼成した。コート重量は１４０ｇ／Ｌで
ある。
第２層の形成
ジニトロジアンミンＰｔ水溶液を活性アルミナ粉末に含
浸し、乾燥後空気中４００℃で１時間焼成して、Ｐｔ担
持アルミナ粉末を得た。この粉末とベーマイト、水、及
び硝酸を磁性ボールミルに投入し、混合粉砕してスラリ
液を得た。粉砕時間を２時間とした。このスラリ液を第
１層を塗布したハニカムの上に塗布し空気流にてセル内
の余剰スラリを取り除いて１３０℃で乾燥した後、４０
０℃で１時間焼成し、第２層のコート層重量を９１ｇ／
Ｌとした。
Ｃｅの含侵
これを酢酸セリウム水溶液中に浸漬し、空気流にて余剰
の酢酸Ｃｅ液を取り除き、１３０℃で乾燥した後４００
℃で１時間焼成し、ＣｅをＣｅＯ２が５ｇ／Ｌとなるよ
うに含浸担持した。
第３層の形成
ジニトロジアンミンＰｔ水溶液を活性アルミナ粉末に含
浸し、乾燥後空気中４００℃で１時間焼成して、Ｐｔ担
持アルミナ粉末を得た。次に、硝酸Ｒｈ水溶液を活性ア
ルミナ粉末に含浸し、乾燥後空気中４００℃で１時間焼
成して、Ｒｈ担持アルミナ粉末を得た。これら粉末、活
性アルミナ粉末、ベーマイト、水、及び硝酸を磁性ボー
ルミルに投入し、混合粉砕してスラリ液を得た。粉砕時
間を２時間とした。このスラリ液を第２層を塗布したモ
ノリス担体の上に塗布し、空気流にてセル内の余剰スラ
リを取り除いて１３０℃で乾燥した後、４００℃で１時
間焼成し、第３層のコート層重量７７ｇ／Ｌ−担体を得
た。(Example 1) (1) Preparation of Downstream Catalyst First layer (bottom layer) formation Activated alumina powder, boehmite alumina and nitric acid were put in a pot container and crushed for 1 hr by a ball mill. The inner layer slurry liquid was used as a cordierite monolith carrier (0.9
4L, 2 mil 900 cells / in 2),
Excessive slurry in the cell is removed by air flow and dried.
It was baked at 00 ° C. for 1 hour. The coat weight is 140 g / L. Formation of Second Layer A dinitrodiammine Pt aqueous solution was impregnated in activated alumina powder, dried and then baked in air at 400 ° C. for 1 hour to obtain a Pt-supported alumina powder. This powder, boehmite, water, and nitric acid were put into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. The grinding time was 2 hours. The slurry was applied onto the honeycomb coated with the first layer, the excess slurry in the cells was removed by air flow, and the slurry was dried at 130 ° C.
Baking for 1 hour at 0 ° C., the weight of the second coat layer is 91 g /
It was set to L. Impregnation of Ce This was immersed in an aqueous solution of cerium acetate, the excess Ce acetate solution was removed with an air stream, and the mixture was dried at 130 ° C.
The mixture was baked at 1 ° C. for 1 hour, and Ce was impregnated and supported so that CeO 2 became 5 g / L. Formation of Third Layer A dinitrodiammine Pt aqueous solution was impregnated in activated alumina powder, dried and then baked in air at 400 ° C. for 1 hour to obtain a Pt-supported alumina powder. Next, an activated alumina powder was impregnated with a Rh aqueous solution of nitric acid, dried and then baked in air at 400 ° C. for 1 hour to obtain an Rh-supported alumina powder. These powders, activated alumina powder, boehmite, water, and nitric acid were put into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. The grinding time was 2 hours. This slurry solution is applied on the monolith carrier coated with the second layer, the excess slurry in the cell is removed by an air stream, dried at 130 ° C., and then baked at 400 ° C. for 1 hour to coat the third layer. A layer weight of 77 g / L-carrier was obtained.
【００２８】なお、表１に示すように、本例の触媒中の
第１層のコート重量はアルミナ分が１４０ｇ、ＣｅＯ２
の含有量は第２層塗布後に含侵するので、第２層、第１
層に均一に分布しているものとして、第１層のＣｅＯ２
含有分は５ｇ／Ｌ×１４０／（１４０＋９１）＝３ｇと
し、合計で１４３ｇ／Ｌとした。従って、第１層におけ
るＣｅＯ２含有量は２％である。単位セルピッチ当たり
の触媒層面積の割合は２７．６％とした。これは７０倍
のＳＥＭ観察写真に基づいて算出した。貴金属含有量は
触媒１Ｌ当たりＰｔが０．５３ｇ、Ｒｈが０．１８ｇで
あった。As shown in Table 1, the coat weight of the first layer in the catalyst of this example contained 140 g of alumina and CeO 2
Since the content of is impregnated after coating the second layer,
CeO 2 of the first layer is assumed to be evenly distributed in the layer.
The content was 5 g / L × 140 / (140 + 91) = 3 g, and was 143 g / L in total. Therefore, the CeO 2 content in the first layer is 2%. The ratio of the catalyst layer area per unit cell pitch was set to 27.6%. This was calculated based on a 70 times SEM observation photograph. The noble metal content was 0.53 g of Pt and 0.18 g of Rh per 1 L of the catalyst.
【００２９】（２）上流側触媒の準備
第１層の形成
活性アルミナ粉末とベーマイトアルミナ及び硝酸をポッ
ト容器に入れてボールミルにて１ｈｒ粉砕した。この内
層スラリー液をコージェライト質モノリス担体（０．９
４Ｌ、２ミル ９００セル／平方インチ）に塗布し、空
気流にてセル内の余剰のスラリーを除去・乾燥し、４０
０℃で１時間焼成した。コート重量は７０ｇ／Ｌであっ
た。
第２層の形成
硝酸Ｒｈ水溶液を活性アルミナ粉末に含浸し、乾燥後空
気中４００℃で１時間焼成して、Ｒｈ担持アルミナ粉末
を得た。この粉末と、活性アルミナ粉末、ベーマイト、
水、及び硝酸を磁性ボールミルに投入し、混合粉砕して
スラリ液を得た。粉砕時間を２時間とした。このスラリ
液を第１層を塗布したモノリス担体の上に塗布し、空気
流にてセル内の余剰スラリを取り除いて１３０℃で乾燥
した後、４００℃で１時間焼成した。
第３層の形成
ジニトロジアンミンＰｄ水溶液を活性アルミナ粉末に含
浸し、乾燥後空気中４００℃で１時間焼成して、Ｐｄ担
持アルミナ粉末を得た。この粉末と、活性アルミナ粉
末、ベーマイト、水、及び硝酸を磁性ボールミルに投入
し、混合粉砕してスラリ液を得た。粉砕時間を２時間と
した。このスラリ液を第２層を塗布したハニカムの上に
塗布し、空気流にてセル内の余剰スラリを取り除いて１
３０℃で乾燥した後、４００℃で１時間焼成した。
Ｂａの含侵
これを酢酸バリウム水溶液中に浸漬し、空気流にて余剰
の酢酸Ｂａ液を取り除き、１３０℃で乾燥した後４００
℃で１時間焼成し、ＢａをＢａＯが５ｇ／Ｌとなるよう
に含浸担持した。なお、表１に示すように、上流側触媒
の単位セルピッチ当たりの触媒層面積の割合は２４．０
％。貴金属含有量は触媒１Ｌ当たりＰｄが１．８８ｇ、
Ｒｈが０．２３ｇであった。(2) Preparation of upstream side catalyst Formation of first layer Activated alumina powder, boehmite alumina and nitric acid were put in a pot container and crushed for 1 hr by a ball mill. The inner layer slurry liquid was used as a cordierite monolith carrier (0.9
4L, 2 mil 900 cells / in2), remove excess slurry in the cell by air flow and dry.
Baking at 0 ° C. for 1 hour. The coat weight was 70 g / L. Formation of Second Layer An aqueous Rh nitrate solution was impregnated in activated alumina powder, dried and then baked in air at 400 ° C. for 1 hour to obtain an Rh-supported alumina powder. With this powder, activated alumina powder, boehmite,
Water and nitric acid were put into a magnetic ball mill, and mixed and pulverized to obtain a slurry liquid. The grinding time was 2 hours. This slurry solution was applied onto the monolith carrier coated with the first layer, the excess slurry in the cell was removed by an air flow, and the slurry was dried at 130 ° C. and then calcined at 400 ° C. for 1 hour. Formation of Third Layer An aqueous solution of dinitrodiammine Pd was impregnated in activated alumina powder, dried and then baked in air at 400 ° C. for 1 hour to obtain a Pd-supported alumina powder. This powder, activated alumina powder, boehmite, water, and nitric acid were put into a magnetic ball mill and mixed and ground to obtain a slurry liquid. The grinding time was 2 hours. This slurry liquid was applied onto the honeycomb coated with the second layer, and the excess slurry in the cells was removed by air flow to
After drying at 30 ° C., it was baked at 400 ° C. for 1 hour. Impregnation of Ba This is immersed in an aqueous solution of barium acetate, the excess Ba acetate solution is removed with an air stream, and the mixture is dried at 130 ° C. and then 400
The mixture was baked at 1 ° C. for 1 hour, and Ba was impregnated and supported so that BaO was 5 g / L. As shown in Table 1, the ratio of the catalyst layer area per unit cell pitch of the upstream side catalyst was 24.0.
%. The noble metal content is 1.88 g of Pd per liter of catalyst,
Rh was 0.23 g.
【００３０】（実施例２）
（１）下流側触媒の準備
貴金属含有量を変更し、触媒１Ｌ当たりＰｔが１．１８
ｇ、Ｒｈが０．２３ｇとした以外は、実施例１と同様の
操作を繰り返して、本例の排ガス浄化触媒を得た。 な
お、表１に示すように、本例の触媒の単位セルピッチ当
たりの触媒層面積の割合は２７％である。
（２）上流側触媒の準備
貴金属含有量を変更し、触媒１Ｌ当たりＰｄが２．５９
ｇ、Ｒｈが０．２３ｇした以外は、実施例１と同様の操
作を繰り返して、本例の排ガス浄化触媒を得た。なお、
表１に示すように、本例の触媒の単位セルピッチ当たり
の触媒層面積の割合は２４％であった。Example 2 (1) Preparation of Downstream Catalyst The noble metal content was changed so that Pt was 1.18 per liter of catalyst.
The same operation as in Example 1 was repeated except that g and Rh were 0.23 g to obtain an exhaust gas purifying catalyst of this example. In addition, as shown in Table 1, the ratio of the catalyst layer area per unit cell pitch of the catalyst of this example is 27%. (2) Preparation of upstream side catalyst Pd is 2.59 per liter of catalyst by changing the noble metal content.
The same operation as in Example 1 was repeated except that g and Rh were 0.23 g to obtain an exhaust gas purification catalyst of this example. In addition,
As shown in Table 1, the ratio of the catalyst layer area per unit cell pitch of the catalyst of this example was 24%.
【００３１】（実施例３）
（１）下流側触媒の準備
第２層の形成後、ＣｅＯ２の含侵重量を２３ｇ／Ｌと
し、第１層におけるＣｅＯ２含有量を９％とした以外
は、実施例２と同様の操作を繰り返して、本例の排ガス
浄化触媒を得た。貴金属含有量は触媒１Ｌ当たりＰｔが
１．１８ｇ、Ｒｈが０．２３ｇであった。なお、本例の
触媒の単位セルピッチ当たりの触媒層面積の割合は２７
％であった。
（２）上流側触媒の準備
実施例２と同様のものを用いた。Example 3 (1) Preparation of Downstream Catalyst After the formation of the second layer, the impregnated weight of CeO 2 was set to 23 g / L, and the CeO 2 content in the first layer was set to 9%. Then, the same operation as in Example 2 was repeated to obtain the exhaust gas purifying catalyst of this example. The noble metal content was 1.18 g of Pt and 0.23 g of Rh per liter of the catalyst. The ratio of the catalyst layer area per unit cell pitch of the catalyst of this example was 27.
%Met. (2) Preparation of upstream catalyst The same catalyst as in Example 2 was used.
【００３２】（比較例１）
（１）下流側触媒の準備
第１層の形成
活性アルミナ粉末とベーマイトアルミナ及び硝酸をポッ
ト容器に入れてボールミルにて１ｈｒ粉砕する。この内
層スラリー液をコージェライト質モノリス担体（０．９
４Ｌ、２ミル ９００セル／平方インチ）に塗布し、空
気流にてセル内の余剰のスラリーを除去・乾燥し、４０
０℃で１時間焼成した。コート重量は７０ｇ／Ｌであっ
た。
第２層の形成
ジニトロジアンミンＰｔ水溶液を活性アルミナ粉末に含
浸し、乾燥後空気中４００℃で１時間焼成して、Ｐｔ担
持アルミナ粉末を得た。この粉末とベーマイト、水、及
び硝酸を磁性ボールミルに投入し、混合粉砕してスラリ
液を得た。粉砕時間を２時間とした。このスラリ液を第
１層を塗布したモノリス担体の上に塗布し空気流にてセ
ル内の余剰スラリを取り除いて１３０℃で乾燥した後、
４００℃で１時間焼成し、第２層のコート層重量を８
４．５ｇ／Ｌとした。
Ｃｅの含侵
Ｃｅの含侵は行わなかった。
第３層の形成
ジニトロジアンミンＰｔ水溶液を活性アルミナ粉末に含
浸し、乾燥後空気中４００℃で１時間焼成して、Ｐｔ担
持アルミナ粉末を得た。次に、硝酸Ｒｈ水溶液を活性ア
ルミナ粉末に含浸し、乾燥後空気中４００℃で１時間焼
成して、Ｒｈ担持アルミナ粉末を得た。これら粉末、活
性アルミナ粉末、ベーマイト、水、及び硝酸を磁性ボー
ルミルに投入し、混合粉砕してスラリ液を得た。粉砕時
間を２時間とした。このスラリ液を第２層を塗布したモ
ノリス担体の上に塗布し、空気流にてセル内の余剰スラ
リを取り除いて１３０℃で乾燥した後、４００℃で１時
間焼成し、コート層重量６０ｇ／Ｌ−担体を得た。な
お、表１に示すように、本例の触媒中の第１層のコート
重量はアルミナ分を７０ｇとした。Ｃｅは含侵していな
いので、第１層におけるＣｅＯ２含有量は０％である。
単位セルピッチ当たりの触媒層面積の割合は１９．０％
であった。貴金属含有量は触媒１Ｌ当たりＰｔが１．１
８ｇ、Ｒｈが０．２３ｇであった。Comparative Example 1 (1) Preparation of Downstream Catalyst First layer formation Activated alumina powder, boehmite alumina and nitric acid were put in a pot container and pulverized for 1 hr by a ball mill. The inner layer slurry liquid was used as a cordierite monolith carrier (0.9
4L, 2 mil 900 cells / in2), remove excess slurry in the cell by air flow and dry.
Baking at 0 ° C. for 1 hour. The coat weight was 70 g / L. Formation of Second Layer A dinitrodiammine Pt aqueous solution was impregnated in activated alumina powder, dried and then baked in air at 400 ° C. for 1 hour to obtain a Pt-supported alumina powder. This powder, boehmite, water, and nitric acid were put into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. The grinding time was 2 hours. This slurry solution is applied on the monolith carrier coated with the first layer, the excess slurry in the cell is removed by air flow, and the slurry is dried at 130 ° C.
Bake at 400 ° C. for 1 hour to reduce the weight of the second coat layer to 8
It was 4.5 g / L. Impregnation of Ce No impregnation of Ce was performed. Formation of Third Layer A dinitrodiammine Pt aqueous solution was impregnated in activated alumina powder, dried and then baked in air at 400 ° C. for 1 hour to obtain a Pt-supported alumina powder. Next, an activated alumina powder was impregnated with a Rh aqueous solution of nitric acid, dried and then baked in air at 400 ° C. for 1 hour to obtain an Rh-supported alumina powder. These powders, activated alumina powder, boehmite, water, and nitric acid were put into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. The grinding time was 2 hours. This slurry solution was applied onto the monolith carrier coated with the second layer, the excess slurry in the cell was removed by an air stream, and dried at 130 ° C, followed by firing at 400 ° C for 1 hour to give a coat layer weight of 60 g / An L-carrier was obtained. As shown in Table 1, the coat weight of the first layer in the catalyst of this example was 70 g of alumina. Since Ce is not impregnated, the CeO 2 content in the first layer is 0%.
The ratio of the catalyst layer area per unit cell pitch is 19.0%.
Met. Noble metal content is 1.1 Pt per liter of catalyst
8g, Rh was 0.23g.
【００３３】（２）上流側触媒の準備 実施例２及び実施例３と同様のものを用いた。(2) Preparation of upstream catalyst The same ones as in Example 2 and Example 3 were used.
【００３４】＜触媒の耐久処理＞排ガス浄化装置の上流
側触媒及び下流側触媒について別々に以下の条件で触媒
の耐久を行った。
エンジン ：日産自動車製６気筒３０００ｃｃ
温度 ：８５０℃（触媒温度）
時間 ：１００時間<Catalyst Durability Treatment> The upstream catalyst and the downstream catalyst of the exhaust gas purifying apparatus were separately subjected to catalyst durability under the following conditions. Engine: Nissan 6-cylinder 3000cc Temperature: 850 ° C (catalyst temperature) Time: 100 hours
【００３５】＜評価試験＞上流側触媒０．５Ｌと下流側
触媒０．５Ｌを組合わせて、表１に示す並びでコンバー
ターケースに入れ排ガス浄化装置を構成した後、以下の
条件で性能を評価した。なお、上流側触媒の耐久処理も
下流側と同様に行った。この結果及びモード評価の結果
を示す。
<Evaluation test> After combining 0.5 L of the upstream side catalyst and 0.5 L of the downstream side catalyst and putting them in the converter case in the arrangement shown in Table 1 to construct an exhaust gas purifying apparatus, the performance was evaluated under the following conditions. did. The durability treatment of the upstream side catalyst was also performed in the same manner as the downstream side. This result and the result of the mode evaluation are shown.
【００３６】[0036]
【表１】 [Table 1]
【００３７】表１に示すように、実施例１〜３で得られ
た排ガス浄化装置は、下流側触媒の単位セルピッチ当た
りの触媒層面積割合が本発明の範囲内にあり、Ｐｄを含
有する触媒を上流側においても、比較例１の装置に対し
て、１０・１５モードのＮＯｘ排出量が少なく、１１モ
ードのＨＣ排出量が少ない。言い換えれば、実施例１〜
３で得られた排ガス浄化装置では、下流側触媒を配置
し、上流側にＰｄのようなＨＣ、ＣＯなどの還元剤を消
費してしまう触媒を設置しても、ホット走行（１０・１
５モード）でのＮＯｘ排出量の低減とコールドスタート
（１１モード）におけるＨＣ排出量の低減を図ることが
できる。As shown in Table 1, in the exhaust gas purifying apparatuses obtained in Examples 1 to 3, the catalyst layer area ratio per unit cell pitch of the downstream side catalyst was within the range of the present invention, and the catalyst containing Pd was used. Even on the upstream side, the NOx emission amount in the 10 · 15 mode and the HC emission amount in the 11 mode are small as compared with the device of Comparative Example 1. In other words, Example 1
In the exhaust gas purifying apparatus obtained in No. 3, even if a downstream catalyst is arranged and a catalyst that consumes a reducing agent such as HC and CO such as Pd is installed on the upstream side, hot running (10 ・ 1
It is possible to reduce the NOx emission amount in the 5th mode) and the HC emission amount in the cold start (11th mode).
【００３８】また、実施例１〜３で得られた排ガス浄化
装置は、下流側触媒の第１層に貴金属を含まないアルミ
ナを１００〜３００ｇ／Ｌ含み、比較例の装置に対し
て、１０・１５モードのＮＯｘ排出量が少なく、１１モ
ードのＨＣ排出量が少ない。更に、実施例１〜３で得ら
れた排ガス浄化装置は、第１層にアルミナ以外にＣｅＯ
２を１〜２０％含有することにより、比較例の装置に対
して、１０・１５モードのＮＯｘ排出量が少なく、１１
モードのＨＣ排出量が少ない。更にまた、実施例１〜３
で得られた排ガス浄化装置は、単位セルピッチ当たりの
触媒層面積割合が上流側触媒より下流側触媒で大きく、
比較例の装置に対して、１０・１５モードのＮＯｘ排出
量が少なく、１１モードのＨＣ排出量が少ない。Further, the exhaust gas purifying apparatuses obtained in Examples 1 to 3 contained 100 to 300 g / L of alumina containing no precious metal in the first layer of the downstream side catalyst, which was 10. NOx emissions in 15 mode are small and HC emissions in 11 mode are small. Further, in the exhaust gas purifying apparatuses obtained in Examples 1 to 3, the first layer was made of CeO in addition to alumina.
By containing 2 to 20%, the NOx emission amount in the 10 · 15 mode is smaller than that of the device of the comparative example.
Mode emission of HC is small. Furthermore, Examples 1-3
In the exhaust gas purifying apparatus obtained in, the catalyst layer area ratio per unit cell pitch is larger in the downstream side catalyst than in the upstream side catalyst,
Compared to the device of the comparative example, the NOx emission amount in the 10/15 mode is small, and the HC emission amount in the 11 mode is small.
【００３９】（実施例４）ジニトロジアンミンＰｔ水溶
液を活性アルミナ粉末に含浸し、乾燥後空気中４００℃
で１時間焼成して、Ｐｔ担持アルミナ粉末を得た。硝酸
Ｒｈ水溶液を活性アルミナ粉末に含浸し、乾燥後空気中
４００℃で１時間焼成して、Ｒｈ担持アルミナ粉末を得
た。これら粉末、活性アルミナ粉末、ベーマイト、水、
及び硝酸を磁性ボールミルに投入し、混合粉砕してスラ
リ液を得た。粉砕時間を２時間とした。このスラリ液を
コーディライト質モノリス担体（１．３Ｌ、４００セ
ル）に付着させ、空気流にてセル内の余剰スラリを取り
除いて１３０℃で乾燥した後、４００℃で１時間焼成
し、コート層重量４００ｇ／Ｌ−担体を得た。これを酢
酸Ｂａ水溶液中に浸漬し、空気流にて余剰の酢酸Ｂａ液
を取り除き、１３０℃で乾燥した後４００℃で１時間焼
成し、Ｂａを含浸担持して、本例の排ガス浄化触媒を得
た。なお、表２に示すように、本例の触媒のアルミナ含
有量は触媒１Ｌ当たり４００ｇ、単位セルピッチ当たり
の触媒層面積の割合は２２．６％、アルミナ粒径は３μ
ｍ、アルミナ比表面積は２００ｇ／ｍ２、貴金属含有量
は触媒１Ｌ当たりＰｔが２．３ｇ、Ｒｈが０．５ｇ、Ｂ
ａ量は酸化物換算で触媒１Ｌ当たり３０ｇであった。Example 4 Activated alumina powder was impregnated with an aqueous solution of dinitrodiammine Pt, dried, and then dried in air at 400 ° C.
Then, it was baked for 1 hour to obtain a Pt-supported alumina powder. An activated alumina powder was impregnated with a Rh aqueous solution of nitric acid, dried and then baked in air at 400 ° C. for 1 hour to obtain an Rh-supported alumina powder. These powders, activated alumina powder, boehmite, water,
And nitric acid were put into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. The grinding time was 2 hours. This slurry liquid was attached to a cordierite monolith carrier (1.3 L, 400 cells), excess slurry in the cells was removed by an air stream, dried at 130 ° C., and then baked at 400 ° C. for 1 hour to form a coating layer. A weight of 400 g / L-carrier was obtained. This is immersed in an aqueous solution of Ba acetate, the excess Ba acetate solution is removed with an air flow, dried at 130 ° C., and then calcined at 400 ° C. for 1 hour to impregnate and carry Ba to carry out the exhaust gas purification catalyst of this example. Obtained. As shown in Table 2, the alumina content of the catalyst of this example was 400 g per liter of catalyst, the ratio of the catalyst layer area per unit cell pitch was 22.6%, and the alumina particle size was 3 μm.
m, the specific surface area of alumina is 200 g / m 2 , the noble metal content is 2.3 g of Pt, 0.5 g of Rh, and B per 1 L of the catalyst.
The amount of a was 30 g per 1 L of catalyst in terms of oxide.
【００４０】（比較例２）活性アルミナ量を触媒１Ｌ当
たり３００ｇとした以外は、実施例４と同様の操作を繰
り返して、本例の排ガス浄化触媒を得た。なお、表２に
示すように、本例の触媒の単位セルピッチ当たりの触媒
層面積の割合は１６．９％であり、それ以外は実施例４
と同様であった。Comparative Example 2 An exhaust gas purifying catalyst of this example was obtained by repeating the same operation as in Example 4 except that the amount of activated alumina was 300 g per 1 L of the catalyst. As shown in Table 2, the ratio of the catalyst layer area per unit cell pitch of the catalyst of this example was 16.9%, and other than that, Example 4 was used.
Was similar to.
【００４１】（実施例５）活性アルミナ量を触媒１Ｌ当
たり６００ｇとした以外は、実施例４と同様の操作を繰
り返して、本例の排ガス浄化触媒を得た。なお、表２に
示すように、本例の触媒の単位セルピッチ当たりの触媒
層面積の割合は３３．８％であり、それ以外は実施例４
と同様であった。Example 5 An exhaust gas purifying catalyst of this example was obtained by repeating the same operation as in Example 4, except that the amount of activated alumina was 600 g per 1 L of the catalyst. In addition, as shown in Table 2, the ratio of the catalyst layer area per unit cell pitch of the catalyst of this example was 33.8%, and other than that, Example 4 was used.
Was similar to.
【００４２】（実施例６）貴金属としてＰｄを加えた以
外は、実施例４と同様の操作を繰り返して、本例の排ガ
ス浄化触媒を得た。なお、表２に示すように、本例の触
媒の貴金属含有量は触媒１Ｌ当たり、Ｐｔが２．３ｇ、
Ｒｈが０．５ｇ、Ｐｄが０．７ｇであった。Example 6 An exhaust gas purifying catalyst of this example was obtained by repeating the same operation as in Example 4, except that Pd was added as a noble metal. As shown in Table 2, the noble metal content of the catalyst of this example was 2.3 g of Pt per 1 L of the catalyst,
Rh was 0.5 g and Pd was 0.7 g.
【００４３】（実施例７）ＢａをＮａとした以外は、実
施例４と同様の操作を繰り返して、本例の排ガス浄化触
媒を得た。なお、表２に示すように、本例の触媒のＮａ
量は酸化物換算で触媒１Ｌ当たり１０ｇであった。Example 7 An exhaust gas purifying catalyst of this example was obtained by repeating the same operation as in Example 4 except that Na was used as Ba. In addition, as shown in Table 2, Na of the catalyst of this example
The amount was 10 g per 1 L of catalyst in terms of oxide.
【００４４】（実施例８）ＢａをＣｓとした以外は、実
施例４と同様の操作を繰り返して、本例の排ガス浄化触
媒を得た。なお、表２に示すように、本例の触媒のＣｓ
量は酸化物換算で触媒１Ｌ当たり２０ｇであった。(Example 8) The same operation as in Example 4 was repeated except that Ba was changed to Cs to obtain an exhaust gas purifying catalyst of this example. As shown in Table 2, the Cs of the catalyst of this example was
The amount was 20 g per 1 L of catalyst in terms of oxide.
【００４５】［評価試験］
・耐久方法
排気量４４００ｃｃのエンジンの排気系に触媒を装着
し、上流側の触媒入口温度を６００℃とし、５０時間運
転した。
・評価方法
排気量２０００ｃｃのエンジンの排気系に触媒を装着
し、Ａ／Ｆ＝１４．６を１０秒→Ａ／Ｆ＝１１．０を２
秒→Ａ／Ｆ＝２２．０を２０秒、の運転を繰り返した。
触媒入口温度を３５０℃とした。この切り替え運転１サ
イクルのトータル転化率を求めた。この結果を表３に示
す。[Evaluation Test] Durability Method A catalyst was attached to the exhaust system of an engine having a displacement of 4400 cc, the catalyst inlet temperature on the upstream side was set to 600 ° C., and operation was performed for 50 hours. -Evaluation method A catalyst is attached to the exhaust system of an engine with a displacement of 2000 cc, and A / F = 14.6 for 10 seconds-> A / F = 11.0
The operation of second → A / F = 22.0 for 20 seconds was repeated.
The catalyst inlet temperature was 350 ° C. The total conversion rate for one cycle of this switching operation was determined. The results are shown in Table 3.
【００４６】[0046]
【表２】 [Table 2]
【００４７】[0047]
【表３】 [Table 3]
【００４８】表２及び表３に示すように、実施例４〜８
で得られた排ガス浄化触媒は、単位セルピッチ当たりの
触媒層面積が本発明の範囲内にあるので、比較例２の触
媒に対して、ＮＯ転化率が向上していることがわかる。As shown in Tables 2 and 3, Examples 4 to 8
The exhaust gas purifying catalyst obtained in 1. above has a catalyst layer area per unit cell pitch within the range of the present invention, so it can be seen that the NO conversion rate is improved with respect to the catalyst of Comparative Example 2.
【００４９】以上、本発明を実施例及び比較例により詳
細に説明したが、本発明はこれら実施例に限定されるも
のではなく、本発明の要旨の範囲内において種々の変形
が可能である。例えば、本発明の触媒は、ガソリン、デ
ィーゼルに特にとらわれずに使用可能である。また、リ
ーン・リッチ・ストイキのＡ／Ｆ、時間、温度について
は本評価方法の範囲に特に限定されない。Although the present invention has been described in detail with reference to Examples and Comparative Examples, the present invention is not limited to these Examples, and various modifications can be made within the scope of the gist of the present invention. For example, the catalyst of the present invention can be used regardless of gasoline or diesel. The lean rich stoichiometric A / F, time, and temperature are not particularly limited to the range of this evaluation method.
【００５０】[0050]
【発明の効果】以上説明してきたように、本発明によれ
ば、触媒成分を所定の面積割合で担体に担持することと
したため、酸素が過剰となっても優れたＮＯｘ浄化性能
を発揮でき、またコールド時のＨＣ、ＣＯ性能を保持し
つつ、ホット時にＨＣ、ＣＯが少ない条件下でもＮＯｘ
性能を両立できる排ガス浄化触媒及び排ガス浄化装置を
提供することができる。As described above, according to the present invention, since the catalyst component is supported on the carrier in a predetermined area ratio, excellent NOx purification performance can be exhibited even if oxygen is excessive. In addition, while maintaining the HC and CO performance during cold, NOx even under conditions with a small amount of HC and CO during hot
It is possible to provide an exhaust gas purifying catalyst and an exhaust gas purifying apparatus that are compatible in performance.
【図１】単位セルピッチに担持されて成る触媒層の一例
を示す概略図である。FIG. 1 is a schematic view showing an example of a catalyst layer supported on a unit cell pitch.
【図２】セル角の最厚部及び平坦部の最薄部を示す概略
図である。FIG. 2 is a schematic view showing the thickest part of the cell angle and the thinnest part of the flat part.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｆ０１Ｎ 3/28 ３０１ Ｂ０１Ｄ 53/36 １０１Ｂ Ｂ０１Ｊ 23/56 ３０１Ａ (72)発明者 若松 広憲 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内 (72)発明者 伊藤 淳二 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内 Ｆターム(参考） 3G091 AA02 AA06 AA12 AA17 AA18 AB03 AB04 AB05 AB06 BA01 BA03 BA14 BA15 BA19 BA39 FB02 FB03 FC07 FC08 GA06 GA18 GB02W GB03W GB04W GB05W GB06W GB07W GB17W GB17X 4D048 AA06 AA13 AA18 AB02 AB05 AB07 BA01Y BA02Y BA03X BA14Y BA15Y BA19X BA30X BA31X BA32Y BA33X BA34Y BA41X BB02 BB17 CC32 CC36 CC46 DA03 DA11 4G069 AA03 AA08 BA01A BA01B BA13B BB04A BB04B BC01A BC02A BC03A BC06A BC08A BC09A BC10A BC12A BC13A BC32A BC33A BC43A BC43B BC69A BC71A BC71B BC72A BC72B BC75A BC75B CA03 CA08 CA09 DA06 EA18 EA19 EB15X EB15Y EB18X EC03X EC21X EC28 FA01 FA02 FA03 FB14 FB15 FB19 FB30 FC08 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 7 Identification code FI theme code (reference) F01N 3/28 301 B01D 53/36 101B B01J 23/56 301A (72) Inventor Hironori Wakamatsu Kanagawa Yokohama Kanagawa 2 Takara-cho, Ward Nissan Motor Co., Ltd. (72) Inventor Junji Ito 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa F-Term Nissan Motor Co., Ltd. (reference) 3G091 AA02 AA06 AA12 AA17 AA18 AB03 AB04 AB05 AB06 BA01 BA03 BA14 BA15 BA19 BA39 FB02 FB03 FC07 FC08 GA06 GA18 GB02W GB03W GB04W GB05W GB06W GB07W GB17W GB17X 4D048 AA06 AA13 AA18 AB02 AB05 AB07 BA01Y BA02Y BA03X BA14Y BA15Y BA19B01 BA01B03A04A04B03B04A04A46A04B03B04A04B30ABA23ABA23BBABBAA13B04B04A01 BC02A BC03A BC06A BC08A BC09A BC10A BC12A BC13A BC32A BC33A BC43A BC43B BC69A BC71A BC71B BC72A BC72B BC75A BC75B CA03 CA08 CA09 DA06 EA18 EA19 EB15X EB15Y EB18X EC03X EC21X EC28 FA01 FA02 FA03 FB14 FB15 FB19 FB30 FC08
Claims (12)
を含む触媒成分が担持されて成る排ガス浄化触媒であっ
て、 上記触媒成分が次の式１ ２０％＜単位セルピッチ当たりの触媒層の面積割合＜３５％ …（１） で表される触媒層を形成して成ることを特徴とする排ガ
ス浄化触媒。1. An exhaust gas purifying catalyst comprising a monolith carrier and a catalyst component containing a noble metal and alumina supported thereon, wherein the catalyst component is represented by the following formula 1 20% <area ratio of catalyst layer per unit cell pitch < 35% ... An exhaust gas purifying catalyst, characterized by comprising a catalyst layer represented by (1).
は貴金属を含まず且つアルミナを主成分とし、これ以外
の少なくとも１層は貴金属を含有して成り、該最下層の
密度は１００〜３００ｇ／Ｌであることを特徴とする排
ガス浄化触媒。2. The catalyst component forms a laminate, the lowermost layer contains no precious metal and contains alumina as a main component, and at least one other layer contains the precious metal, and the density of the lowermost layer is 100. An exhaust gas purifying catalyst, characterized in that it is from 300 g / L.
ｅＯ２換算で１〜２０％の割合でセリウムを更に含有し
て成ることを特徴とする排ガス浄化触媒。3. The bottom layer is C with respect to the mass of the bottom layer.
An exhaust gas purifying catalyst, which further comprises cerium at a ratio of 1 to 20% in terms of eO 2 .
成る排ガス浄化装置であって、 当該排ガス浄化触媒の上流側にパラジウムを含有する触
媒を配設して成ることを特徴とする排ガス浄化装置。4. An exhaust gas purifying apparatus using the exhaust gas purifying catalyst according to claim 1, wherein a catalyst containing palladium is arranged on the upstream side of the exhaust gas purifying catalyst. apparatus.
ピッチ当たりの面積割合は、上流側に配設する触媒の該
面積割合より大きいことを特徴とする請求項４に記載の
排ガス浄化装置。5. The exhaust gas purifying apparatus according to claim 4, wherein the area ratio of the catalyst layer of the exhaust gas purifying catalyst per unit cell pitch is larger than the area ratio of the catalyst arranged on the upstream side.
金属及び／又はアルカリ土類金属と、アルミナと、を含
む触媒成分が担持されて成る排ガス浄化触媒であって、 上記触媒成分が次の式２ ２０％＜単位セルピッチ当たりの触媒層の面積割合＜３５％ …（２） で表される触媒層を形成し、空燃比が理論空燃比よりリ
ーン域のときにＮＯｘを吸着し、ストイキ〜リッチ域の
ときに吸着したＮＯｘを窒素に還元することを特徴とす
る排ガス浄化触媒。6. An exhaust gas purifying catalyst comprising a monolith carrier and a catalyst component containing a noble metal, an alkali metal and / or an alkaline earth metal, and alumina, the catalyst component having the following formula: 220% <Area ratio of catalyst layer per unit cell pitch <35% (2) A catalyst layer is formed and NOx is adsorbed when the air-fuel ratio is leaner than the theoretical air-fuel ratio, and stoichiometric to rich. An exhaust gas purifying catalyst characterized by reducing NOx adsorbed in a certain range to nitrogen.
であることを特徴とする請求項６に記載の排ガス浄化触
媒。7. The total weight of the catalyst layer is 400 to 600 g.
The exhaust gas purifying catalyst according to claim 6, wherein
〜１０ｇの割合で含有し、上記アルカリ金属及び／又は
アルカリ土類金属を触媒容量１Ｌ当たり５〜８０ｇの割
合で含有して成ることを特徴とする請求項６又は７に記
載の排ガス浄化触媒。8. The noble metal is added in an amount of 0.5 per 1 L of the catalyst volume.
The exhaust gas purifying catalyst according to claim 6 or 7, wherein the catalyst is contained in a ratio of 10 to 10 g, and the alkali metal and / or alkaline earth metal is contained in a ratio of 5 to 80 g per 1 L of the catalyst capacity.
ウムから成る群より選ばれた少なくとも１種のものであ
り、上記アルカリ金属及び／又はアルカリ土類金属がマ
グネシウム、カルシウム、ストロンチウム、バリウム、
ナトリウム、カリウム及びセシウムから成る群より選ば
れた少なくとも１種のものであることを特徴とする請求
項６〜８のいずれか１つの項に記載の排ガス浄化触媒。9. The noble metal is at least one selected from the group consisting of platinum, rhodium and palladium, and the alkali metal and / or alkaline earth metal is magnesium, calcium, strontium, barium,
The exhaust gas purifying catalyst according to any one of claims 6 to 8, which is at least one selected from the group consisting of sodium, potassium and cesium.
対して７０〜９５％の割合で含有して成ることを特徴と
する請求項６〜９のいずれか１つの項に記載の排ガス浄
化触媒。10. The exhaust gas purifying catalyst according to any one of claims 6 to 9, wherein the alumina is contained in a proportion of 70 to 95% with respect to the total weight of the catalyst layer. .
径）が１〜４μｍであることを特徴とする請求項６〜１
０のいずれか１つの項に記載の排ガス浄化触媒。11. An average particle diameter (median diameter) of the alumina is 1 to 4 μm.
The exhaust gas purifying catalyst according to any one of 0.
００ｍ２／ｇであることを特徴とする請求項６〜１１の
いずれか１つの項に記載の排ガス浄化触媒。12. The specific surface area of the alumina is 100 to 3
It is 00 m < 2 > / g, The exhaust gas purifying catalyst according to any one of claims 6 to 11, which is characterized in that.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002234811A JP2003200061A (en) | 2001-11-02 | 2002-08-12 | Exhaust gas purifying catalyst and exhaust gas purifying device |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001-338218 | 2001-11-02 | ||
| JP2001338218 | 2001-11-02 | ||
| JP2002234811A JP2003200061A (en) | 2001-11-02 | 2002-08-12 | Exhaust gas purifying catalyst and exhaust gas purifying device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2003200061A true JP2003200061A (en) | 2003-07-15 |
Family
ID=27666849
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002234811A Pending JP2003200061A (en) | 2001-11-02 | 2002-08-12 | Exhaust gas purifying catalyst and exhaust gas purifying device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2003200061A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004267850A (en) * | 2003-03-06 | 2004-09-30 | Ict:Kk | Exhaust gas cleaning catalyst and manufacturing method therefor |
| JP2010179204A (en) * | 2009-02-03 | 2010-08-19 | Toyota Motor Corp | Catalyst for cleaning exhaust gas |
| WO2013027867A3 (en) * | 2011-08-24 | 2013-04-18 | Kabushiki Kaisha Toyota Jidoshokki | Exhaust gas purification catalyst |
| WO2015079908A1 (en) * | 2013-11-28 | 2015-06-04 | 株式会社キャタラー | Exhaust gas purification catalyst |
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| JPH03154635A (en) * | 1989-11-08 | 1991-07-02 | Engelhard Corp | Three-way conversion catalyst comprising ceria containing zirconium carrier |
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|---|---|---|---|---|
| JP2004267850A (en) * | 2003-03-06 | 2004-09-30 | Ict:Kk | Exhaust gas cleaning catalyst and manufacturing method therefor |
| JP2010179204A (en) * | 2009-02-03 | 2010-08-19 | Toyota Motor Corp | Catalyst for cleaning exhaust gas |
| WO2013027867A3 (en) * | 2011-08-24 | 2013-04-18 | Kabushiki Kaisha Toyota Jidoshokki | Exhaust gas purification catalyst |
| WO2015079908A1 (en) * | 2013-11-28 | 2015-06-04 | 株式会社キャタラー | Exhaust gas purification catalyst |
| JPWO2015079908A1 (en) * | 2013-11-28 | 2017-03-16 | 株式会社キャタラー | Exhaust gas purification catalyst |
| US9833771B2 (en) | 2013-11-28 | 2017-12-05 | Cataler Corporation | Exhaust gas purifying catalyst |
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