JP3818062B2 - Exhaust gas purification catalyst - Google Patents
Exhaust gas purification catalyst Download PDFInfo
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- JP3818062B2 JP3818062B2 JP2001002575A JP2001002575A JP3818062B2 JP 3818062 B2 JP3818062 B2 JP 3818062B2 JP 2001002575 A JP2001002575 A JP 2001002575A JP 2001002575 A JP2001002575 A JP 2001002575A JP 3818062 B2 JP3818062 B2 JP 3818062B2
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- exhaust gas
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- 239000003054 catalyst Substances 0.000 title claims description 33
- 238000000746 purification Methods 0.000 title claims description 29
- 229910052697 platinum Inorganic materials 0.000 claims description 18
- 229910052763 palladium Inorganic materials 0.000 claims description 9
- 229910052779 Neodymium Inorganic materials 0.000 claims description 6
- 229910052772 Samarium Inorganic materials 0.000 claims description 6
- 229910052796 boron Inorganic materials 0.000 claims description 6
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 5
- 229910052788 barium Inorganic materials 0.000 claims description 5
- 229910052712 strontium Inorganic materials 0.000 claims description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 40
- 239000007789 gas Substances 0.000 description 25
- 239000000843 powder Substances 0.000 description 16
- 239000000203 mixture Substances 0.000 description 15
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 13
- 239000002131 composite material Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Chemical compound [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 8
- 230000007423 decrease Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 230000001590 oxidative effect Effects 0.000 description 8
- 101150058765 BACE1 gene Proteins 0.000 description 7
- 239000002253 acid Substances 0.000 description 7
- 239000013078 crystal Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- 230000001603 reducing effect Effects 0.000 description 6
- 229910000510 noble metal Inorganic materials 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 229910004631 Ce(NO3)3.6H2O Inorganic materials 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 229910005560 Gd(NO3)3.6H2O Inorganic materials 0.000 description 3
- 229910017498 Nd(NO3)3.6H2O Inorganic materials 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- MWFSXYMZCVAQCC-UHFFFAOYSA-N gadolinium(iii) nitrate Chemical compound [Gd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O MWFSXYMZCVAQCC-UHFFFAOYSA-N 0.000 description 3
- CFYGEIAZMVFFDE-UHFFFAOYSA-N neodymium(3+);trinitrate Chemical compound [Nd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O CFYGEIAZMVFFDE-UHFFFAOYSA-N 0.000 description 3
- UJVRJBAUJYZFIX-UHFFFAOYSA-N nitric acid;oxozirconium Chemical compound [Zr]=O.O[N+]([O-])=O.O[N+]([O-])=O UJVRJBAUJYZFIX-UHFFFAOYSA-N 0.000 description 3
- -1 oxygen ion Chemical class 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 229910008337 ZrO(NO3)2.2H2O Inorganic materials 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910021116 Sm(NO3)3.6H2O Inorganic materials 0.000 description 1
- 229910006219 ZrO(NO3)2·2H2O Inorganic materials 0.000 description 1
- 125000005595 acetylacetonate group Chemical group 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 229910052809 inorganic oxide Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- YZDZYSPAJSPJQJ-UHFFFAOYSA-N samarium(3+);trinitrate Chemical compound [Sm+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O YZDZYSPAJSPJQJ-UHFFFAOYSA-N 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、自動車用エンジン等の内燃機関から排出される排気ガスを浄化するための排気ガス浄化触媒に関し、より詳しくは、高温での耐久性能に優れた排気ガス浄化用触媒に関する。
【０００２】
【従来の技術】
自動車等の排気ガスを処理する触媒には、アルミナ等の無機酸化物の担体上に白金等の貴金属を担持させた三元触媒が有効であることが知られている。
また、従来の三元触媒にリーン雰囲気でＮＯxを吸蔵する機能を付加し、空燃比（Ａ／Ｆ）が高い酸化性雰囲気下でＮＯxを吸蔵させ、一時的な空燃比が低い還元性雰囲気下でＮＯxを還元して排気ガスを浄化する吸蔵還元型ＮＯx浄化用触媒が有効であることが知られている。
【０００３】
しかるに、アルミナ等の担体に貴金属を担持させた触媒系では、触媒が高温になると貴金属が凝集して肥大粒子になる、いわゆるシンタリングが生じ、貴金属の活性表面が減少して触媒性能が低下するという問題がある。
【０００４】
この触媒温度は、自動車を高速で走行させると、短時間で高温に達するため、高温でも劣化せずに排気ガスの浄化性能を維持する触媒が要請されている。また、高性能エンジンの開発動向に伴い、かかる要請は一層顕著になっている。
具体的には、酸化性と還元性の雰囲気が繰り返される１０００℃の高温下でも劣化せずに浄化性能を維持することができる排気ガス浄化用触媒が要請されている。
【０００５】
このため、本出願人は、先に特開平１０−３５８号、特開平１０−２８８６４号において、特定の化学構造を有する白金複合酸化物を用いた排気ガス浄化用触媒を提案している。これらの白金複合酸化物においては、白金元素が複合酸化物の化学構造の中に取り込まれ、かつこの特定の白金複合酸化物の化学構造は高温でも安定である。したがって、かかる白金複合酸化物を用いた触媒は、高温でも白金が複合酸化物の結晶構造内に分配された状態を維持することにより、優れた高温耐久性能を有することができる。
【０００６】
また、特定のペロブスカイト型複合酸化物はＮＯxをＮ2とＯ2に分解する作用を有することが知られており、例えば、特開平５−１５４３８４号公報、特開平５−１８４９３０号公報、特開平５−２４５３７２号公報、特開平５−２６１２８９号公報に、特定のペロブスカイト型複合酸化物を担体に担持したＮＯx接触還元用触媒が記載されている。
【０００７】
【発明が解決しようとする課題】
しかしながら、上記の白金複合酸化物は、高温での耐久性能をより改良する必要があった。また、従来のペロブスカイト型複合酸化物は、酸化性と還元性の雰囲気が繰り返される１０００℃の高温下では、分解が生じるという問題があり、自動車用エンジン等の内燃機関から排出される排気ガスの浄化に使用するためには、排気ガス中のＮＯx、ＨＣの浄化率を高める必要もあった。
【０００８】
したがって、本発明は、酸化性と還元性の雰囲気が繰り返される１０００℃の高温下でも劣化せずに安定して排気ガスを浄化することができる、耐久性能に優れた排気ガス浄化用触媒を提供することを目的とする。
【０００９】
【課題を解決するための手段】
上記の目的は、化学式：ＡＣｅ1-x-y-zＢ’xＺｒyＢ”zＯ3（Ａは、ＢａとＳｒの少なくとも１種、Ｂ’は、Ｎｄ、Ｓｍ、及びＧｄの少なくとも１種、Ｂ”は、ＰｔとＰｄの少なくとも１種、０＜ｘ＜０．５、０＜ｙ＜０．５、０＜ｚ≦０．５、但し１＞（ｘ＋ｙ＋ｚ）。）で表されるペロブスカイト型複合酸化物を含んでなることを特徴とする排気ガス浄化用触媒によって達成される。
【００１０】
本発明は、セリウム（Ｃｅ）とジルコニウム（Ｚｒ）を必須の構成元素とし、バリウム（Ｂａ）とストロンチウム（Ｓｒ）から選択された少なくとも１種のアルカリ土類金属元素、ネオジム（Ｎｄ）、サマリウム（Ｓｍ）、及びガドリニウム（Ｇｄ）から選択された少なくとも１種の希土類金属元素、及び白金（Ｐｔ）とパラジウム（Ｐｄ）から選択された少なくとも１種の貴金属元素を構成元素とするペロブスカイト型複合酸化物を含んでなる、高温下の耐久性能に優れた排気ガス浄化用触媒である。
【００１１】
こうした特定のペロブスカイト型複合酸化物が高い耐久性能を有する理由は、必ずしも明らかではないが、本発明者は次のように推察する。
Ｃｅは、それ自身の性質として酸素貯蔵性能を有するため、酸化性と還元性の雰囲気が繰り返される中で、その酸化性と還元性の変動幅を軽減する作用を奏すると考えられる。そして、本発明のペロブスカイト型複合酸化物では、Ｐｔ又はＰｄは、Ｃｅと同じ結晶単位の中に存在するため、この作用は、Ｐｔ又はＰｄに対して効果的に働き、酸化性と還元性の雰囲気変動がもたらすＰｔ又はＰｄのシンタリングが軽減されるものと考えられる。
【００１２】
Ｎｄ、Ｓｍ、又はＧｄは、ペロブスカイト型複合酸化物のＢサイトのＣｅを一部置換することで、ペロブスカイト型複合酸化物の酸素イオン伝導性を全体的に高めると考えられる。したがって、雰囲気ガスとペロブスカイト型複合酸化物結晶の間で酸素の移動が促進され、Ｃｅの酸素貯蔵性能がさらに高められ、上記のＰｔ又はＰｄのシンタリング抑制が一層効果的になるものと考えられる。
【００１３】
Ｚｒは、その酸化物は本来高い耐熱性を有することから、Ｚｒが結晶格子の一部を置換することで、結晶構造の安定性を高め、酸化性と還元性の雰囲気が繰り返される中での耐熱性を高めるものと考えられる。
Ｐｔ又はＰｄは、本来の性質として排気ガス浄化に対する触媒活性を提供するものと考えられる。
【００１４】
このようなＮｄ等による酸素イオン伝導性、Ｚｒによる耐熱性、Ｐｔ等による触媒活性は、ペロブスカイト型複合酸化物のＢサイトのＣｅを一部置換することにより発現するため、ペロブスカイト型複合酸化物には、本発明で限定するような組成上の最適な範囲があるものと考えられる。
【００１５】
この組成上の最適範囲としては、化学式：ＡＣｅ1-x-y-zＢ’xＺｒyＢ”zＯ3で表されるペロブスカイト型複合酸化物において、０＜ｘ＜０．５であり、好ましくは０．０５＜ｘ＜０．４、より好ましくは０．０５＜ｘ＜０．３であり、０＜ｙ＜０．５であり、好ましくは０．０５＜ｙ＜０．４、より好ましくは０．１＜ｙ＜０．２５であり、０＜ｚ≦０．５であり、好ましくは０．１５＜ｚ＜０．５、より好ましくは０．１＜ｚ＜０．４である。
【００１６】
【発明の実施の形態】
上記の化学式：ＡＣｅ1-x-y-zＢ’xＺｒyＢ”zＯ3（Ａは、ＢａとＳｒの少なくとも１種、Ｂ’は、Ｎｄ、Ｓｍ、及びＧｄの少なくとも１種、Ｂ”は、ＰｔとＰｄの少なくとも１種、０＜ｘ＜０．５、０＜ｙ＜０．５、０＜ｚ≦０．５、但し１＞（ｘ＋ｙ＋ｚ）。）で表されるペロブスカイト型複合酸化物は、各種の方法によって製造することができる。
例えば、上記のペロブスカイト型複合酸化物に含まれる元素Ｂａ、Ｓｒ、Ｃｅ、Ｎｄ、Ｓｍ、Ｇｄ、Ｚｒ、Ｐｔ、Ｐｄの硝酸塩、炭酸塩等の無機化合物、又はアルコキシド、アセチルアセトナト等の有機化合物を所定の割合で混合し、次いで大気雰囲気下で６００〜１１００℃の温度で焼成することにより製造することができる。
【００１７】
好ましくは、上記の無機化合物を所定の割合で含む水溶液を作成し、次いでアンモニア等の添加によって水溶液のｐＨを調節して析出物を調製する、又は上記の有機化合物を所定の割合で含むアルコール溶液を作成し、次いで水を添加して加水分解により析出物を調製するといったような、溶液を介して前駆体を調製し、次いでこれらの前駆体を焼成してペロブスカイト型複合酸化物を製造する。こうした溶液を介することで、均一な組成のペロブスカイト型複合酸化物が得られ易いためである。
【００１８】
得られたペロブスカイト型複合酸化物は、必要により、破砕又は粉砕等を行って粒度を調整し、高温耐久性能に優れた排気ガス浄化用触媒として使用することができる。
こうした排気ガス浄化用触媒を一般的なハニカム型触媒として使用するには、通常の仕方でハニカム基材上に上記のペロブスカイト型複合酸化物の粉末をウオッシュコート等により担持することで可能である。
以下、実施例によって本発明をより具体的に説明する。
【００１９】
【実施例】
実施例１
２４．３８ｇの硝酸バリウムＢａ(ＮＯ3)2、２４．３０６ｇの硝酸セリウムＣｅ(ＮＯ3)3・６Ｈ2Ｏ、４．２１１ｇの硝酸ガドリニウムＧｄ(ＮＯ3)3・６Ｈ2Ｏ、４．９８６６ｇのオキシ硝酸ジルコニウムＺｒＯ(ＮＯ3)2・２Ｈ2Ｏ、４．８３２６ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏを原料として用い、これらを７５０ｇのイオン交換水に添加し、１時間攪拌してこれらの原料の水溶液を作成し、この水溶液に２８％アンモニア水溶液を１５ｇ添加し、２時間攪拌した。得られた析出物を１２０℃の大気雰囲気中で１２時間乾燥し、次いで３００℃の大気雰囲気中で１時間仮焼した。
この仮焼した粉末を粉砕し、次いで７００℃の大気雰囲気中で５時間焼成してＢａＣｅ0.6Ｇｄo.1Ｚｒ0.2Ｐｔ0.1Ｏ3 の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２０】
実施例２
４．２１１ｇの硝酸ガドリニウムＧｄ(ＮＯ3)3・６Ｈ2Ｏに代えて４．５３３６ｇの硝酸サマリウムＳｍ(ＮＯ3)3・６Ｈ2Ｏを原料として用いた以外は実施例１と同様にしてＢａＣｅ0.6Ｓｍo.1Ｚｒ0.2Ｐｔ0.1Ｏ3 の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２１】
実施例３
４．２１１ｇの硝酸ガドリニウムＧｄ(ＮＯ3)3・６Ｈ2Ｏに代えて４．０８９５ｇの硝酸ネオジムＮｄ(ＮＯ3)3・６Ｈ2Ｏを原料として用いた以外は実施例１と同様にしてＢａＣｅ0.6Ｎｄo.1Ｚｒ0.2Ｐｔ0.1Ｏ3 の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２２】
実施例４
４．８３２６ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏに代えて２．１５ｇの硝酸パラジウムＰｄ(ＮＯ3)3を原料として用いた以外は実施例３と同様にしてＢａＣｅ0.6Ｎｄo.1Ｚｒ0.2Ｐｄ0.1Ｏ3 の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２３】
実施例５
４．８３２６ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏに代えて３．６２４５ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏと０．５３７５ｇの硝酸パラジウムＰｄ(ＮＯ3)3を原料として用いた以外は実施例３と同様にしてＢａＣｅ0.6Ｎｄo.1Ｚｒ0 .2Ｐｔ0.075Ｐｄ0.025Ｏ3 の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２４】
比較例１
９７．５２ｇの硝酸バリウムＢａ(ＮＯ3)2、４．８３２６ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏを原料として用いた以外は実施例１と同様にしてＢａ4ＰｔＯ6の組成を有する複合酸化物の粉末を得た。
【００２５】
比較例２
２４．３８ｇの硝酸バリウムＢａ(ＮＯ3)2、２４．３０６ｇの硝酸セリウムＣｅ(ＮＯ3)3・６Ｈ2Ｏ、４．９８６６ｇのオキシ硝酸ジルコニウムＺｒＯ(ＮＯ3)2・２Ｈ2Ｏ、９．６６５２ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏを原料として用いた以外は実施例１と同様にしてＢａＣｅ0.6Ｚｒ0.2Ｐｔ0.2Ｏ3の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２６】
比較例３
２４．３８ｇの硝酸バリウムＢａ(ＮＯ3)2、３２．４０８ｇの硝酸セリウムＣｅ(ＮＯ3)3・６Ｈ2Ｏ、４．０８９５ｇの硝酸ネオジムＮｄ(ＮＯ3)3・６Ｈ2Ｏ、４．８３２６ｇの塩化白金酸Ｈ2ＰｔＣｌ6・６Ｈ2Ｏを原料として用いた以外は実施例１と同様にしてＢａＣｅ0.8Ｎｄ0.1Ｐｔ0.1Ｏ3の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２７】
比較例４
２４．３８ｇの硝酸バリウムＢａ(ＮＯ3)2、２８．３５７ｇの硝酸セリウムＣｅ(ＮＯ3)3・６Ｈ2Ｏ、４．９８６６ｇのオキシ硝酸ジルコニウムＺｒＯ(ＮＯ3)2・２Ｈ2Ｏ、４．０８９５ｇの硝酸ネオジムＮｄ(ＮＯ3)3・６Ｈ2Ｏを原料として用いた以外は実施例１と同様にしてＢａＣｅ0.7Ｚｒ0.2Ｎｄ0.1Ｏ3の組成を有するペロブスカイト型複合酸化物の粉末を得た。
【００２８】
その他のペロブスカイト型複合酸化物の例
上記の実施例１〜５と比較例１〜４は、ペロブスカイト型複合酸化物の最適組成の付近で元素の異なる典型的な例、及び比較のための例を挙げたものである。これらの例の他、組成が異なることによる効果を把握するため、実施例で用いたのと同じ原料を割合を変えて用い、ｘ、ｙ、ｚの異なる種々のペロブスカイト型複合酸化物を製造し、上記の例と併せて試験に供した。
【００２９】
−耐久処理−
上記の各種複合酸化物をそれぞれ加圧成形し、次いで粉砕して直径１〜３ｍｍの粒状にした。得られた各粒状物を常圧流通式の耐久処理装置に配置し、空気／燃料（Ａ／Ｆ）の比が１４と１６を１分間ごとに交替する、下記に組成を示すモデル排気ガスの変動雰囲気下で、全ガス量５リットル／分として１０００℃で５時間の耐久処理を行った。
【００３０】
−排気ガス浄化性能試験−
上記の耐久処理をする前と後の各ペロブスカイト型複合酸化物を排気ガス浄化用触媒として用い、それぞれ２ｇの粒状物を排気ガス浄化性能測定装置に入れ、下記に示す組成のモデル排気ガスを全ガス量１５リットル／分として流通させながら、触媒温度を変化させて、ＮＯとＣ3Ｈ6の浄化率を測定した。
【００３２】
【００３３】
−粉末Ｘ線回折（ＸＲＤ）評価−
実施例３と比較例１で得られたそれぞれのペロブスカイト型複合酸化物の粉末について、耐久処理をする前後のＸＲＤチャートをそれぞれ図１と図２に示す。
また、ＸＲＤチャート上で最高ピークを示すスペクトルの面積から、比例計算により構造残存率を求めた。
【００３４】
−結果より−
(1) 結晶構造の安定性
図１と図２に示したＸＲＤチャートから、実施例３と比較例１の粉末の耐久前と耐久後のＸＲＤチャートに現れる変化を比較すると、実施例３では殆ど変化が見られないのに対し、比較例１ではかなりの変化が生じていることが分かる。
また、透過型電子顕微鏡で実施例３と比較例１の粉末粒子を観察したところ、実施例３の粉末粒子には、耐久処理の前後で形態上の変化は見られなかったが、耐久処理後の比較例１の粉末粒子には、シンタリングによるＰｔ粒子の析出が観察された。
【００３５】
また、図４から、ペロブスカイト型複合酸化物に含まれるＺｒの量が増すにつれて、ペロブスカイト型複合酸化物の構造安定性が高くなることが分かる。
これらのことから、本発明で特定するペロブスカイト型複合酸化物は高い耐久性能を有し、この耐久性能にはＺｒの存在が寄与することが分かる。
【００３６】
(2) 高温耐久性能
表１に、実施例１〜５と比較例１〜４の各触媒について、耐久処理の前後でのＮＯとＣ3Ｈ6の５０％浄化温度をまとめて示す。これらの結果から、実施例と比較例とでは、耐久処理後のＮＯとＣ3Ｈ6の浄化性能に顕著な差があることが分かる。
【００３７】
(3) ｘ値の最適範囲
図３は、ペロブスカイト型複合酸化物のＢサイトのＣｅの一部をＧｄで置換することによりＮＯとＣ3Ｈ6の浄化性能が向上し、ｘ値に最適範囲があることを示している。この浄化性能向上の効果は、Ｃｅの一部をＧｄで置換することにより、酸素イオン伝導性が高められるためであり、一方でこの置換量が増すとＣｅ量が減少して酸素貯蔵性能が低下するため、ｘ値に最適範囲があると考えられる。
【００３８】
(4) ｙ値の最適範囲
図４は、ペロブスカイト型複合酸化物のＢサイトのＣｅの一部をＺｒで置換することによりＣ3Ｈ6の浄化性能が向上し、ｙ値に最適範囲があることを示している。この浄化性能向上の効果は、Ｃｅの一部をＺｒで置換することにより、Ｚｒの本来有する耐久性能が発揮されるためであり、一方でこの置換量が増すとＣｅ量が減少して酸素貯蔵性能が低下するため、ｙ値に最適範囲があると考えられる。
【００３９】
(5) ｚ値の最適範囲
図５は、ペロブスカイト型複合酸化物のＢサイトのＣｅの一部をＰｔで置換することによりＮＯとＣ3Ｈ6の浄化性能が向上するが、Ｐｔ量の増加による効果は一定のレベルで飽和することを示している。この浄化性能向上の効果は、Ｃｅの一部をＰｔで置換することにより、Ｐｔの本来有する浄化性能が発揮されるためであり、一方でこの置換量が増すとＣｅ量が減少して酸素貯蔵性能が低下するため、性能向上の効果に一定の限界があると考えられる。
また、図５は、Ｐｔの比較的少ない組成領域でも高い排気ガス浄化性能が発現するといった、Ｐｔ量を低減させ得る本発明の効果もまた明示している。
【００４０】
(6) このように、本発明では、特定のペロブスカイト型複合酸化物を用いることによって高い耐久性能を有する排気ガス浄化用触媒を提供するものであるが、この耐久性能は、酸素貯蔵性能、酸素イオン伝導性、結晶構造の安定性、及び触媒活性のバランスによってもたらされるため、かかるペロブスカイト型複合酸化物には、本発明で限定するような組成上の最適な範囲があるものと考えられる。
【００４１】
【表１】
【発明の効果】
触媒温度が１０００℃を超える高い温度でも劣化せずに触媒性能を維持することができる耐久性能に優れた触媒を提供することができる。
【図面の簡単な説明】
【図１】本発明のペロブスカイト型複合酸化物の耐久処理の前後を比較したＸＲＤチャートである。
【図２】比較例のペロブスカイト型複合酸化物の耐久処理の前後を比較したＸＲＤチャートである。
【図３】ｘ値を変化させたときの触媒浄化性能の変動を示すグラフである。
【図４】ｙ値を変化させたときの触媒浄化性能の変動を示すグラフである。
【図５】ｚ値を変化させたときの触媒浄化性能の変動を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purification catalyst for purifying exhaust gas discharged from an internal combustion engine such as an automobile engine, and more particularly to an exhaust gas purification catalyst having excellent durability performance at high temperatures.
[0002]
[Prior art]
It is known that a three-way catalyst in which a noble metal such as platinum is supported on an inorganic oxide carrier such as alumina is effective as a catalyst for treating exhaust gas of an automobile or the like.
Also, an additional function of absorbing the NO x in lean atmosphere to a conventional three-way catalyst, to occlude NO x at high oxidizing atmosphere air (A / F), a temporary air-fuel ratio is low reductive storage reduction the NO x purification catalyst for purifying exhaust gas by reducing NO x in an atmosphere are known to be effective.
[0003]
However, in a catalyst system in which a noble metal is supported on a support such as alumina, so-called sintering occurs in which the noble metal aggregates into enlarged particles when the temperature of the catalyst becomes high, and the active surface of the noble metal decreases and the catalytic performance decreases. There is a problem.
[0004]
Since this catalyst temperature reaches a high temperature in a short time when the automobile is driven at a high speed, there is a demand for a catalyst that maintains the exhaust gas purification performance without deteriorating even at a high temperature. In addition, with the development trend of high performance engines, such demands are becoming more prominent.
Specifically, there is a demand for an exhaust gas purification catalyst that can maintain purification performance without deterioration even at a high temperature of 1000 ° C. in which an oxidizing and reducing atmosphere is repeated.
[0005]
For this reason, the present applicant has previously proposed an exhaust gas purifying catalyst using a platinum complex oxide having a specific chemical structure in Japanese Patent Laid-Open Nos. 10-358 and 10-28864. In these platinum composite oxides, platinum element is incorporated into the chemical structure of the composite oxide, and the chemical structure of this specific platinum composite oxide is stable even at high temperatures. Therefore, a catalyst using such a platinum composite oxide can have excellent high-temperature durability performance by maintaining the state in which platinum is distributed in the crystal structure of the composite oxide even at high temperatures.
[0006]
In addition, it is known that a specific perovskite type complex oxide has an action of decomposing NO x into N 2 and O 2 , for example, JP-A-5-154384 and JP-A-5-184930. No. 5-245372 and JP-Hei 5-261289, a particular perovskite NO x catalyst for catalytic reduction of the composite oxide was supported on a carrier are described.
[0007]
[Problems to be solved by the invention]
However, the platinum composite oxide has been required to further improve the durability performance at high temperatures. In addition, the conventional perovskite type complex oxide has a problem that decomposition occurs at a high temperature of 1000 ° C. in which an oxidizing and reducing atmosphere is repeated, and the exhaust gas discharged from an internal combustion engine such as an automobile engine is a problem. In order to use it for purification, it was necessary to increase the purification rate of NO x and HC in the exhaust gas.
[0008]
Therefore, the present invention provides an exhaust gas purifying catalyst excellent in durability performance that can stably purify exhaust gas without deterioration even at a high temperature of 1000 ° C. in which oxidizing and reducing atmospheres are repeated. The purpose is to do.
[0009]
[Means for Solving the Problems]
The above object has the formula: ACe 1-xyz B 'x Zr y B "z O 3 (A is at least one of Ba and Sr, B' is Nd, Sm, and at least one Gd, B" Is at least one of Pt and Pd, 0 <x <0.5, 0 <y <0.5, 0 <z ≦ 0.5, where 1> (x + y + z).) This is achieved by an exhaust gas purifying catalyst characterized by comprising a substance.
[0010]
In the present invention, cerium (Ce) and zirconium (Zr) are essential constituent elements, and at least one alkaline earth metal element selected from barium (Ba) and strontium (Sr), neodymium (Nd), samarium ( Sm) and at least one rare earth metal element selected from gadolinium (Gd) and at least one noble metal element selected from platinum (Pt) and palladium (Pd) as perovskite complex oxides Is an exhaust gas purifying catalyst excellent in durability at high temperatures.
[0011]
The reason why such a specific perovskite complex oxide has a high durability performance is not necessarily clear, but the present inventors infer as follows.
Since Ce has oxygen storage performance as its own property, it is considered that the oxidative and reductive atmospheres are repeated, and the oxidative and reducible fluctuation range is reduced. In the perovskite complex oxide of the present invention, Pt or Pd is present in the same crystal unit as Ce. Therefore, this action works effectively on Pt or Pd, and has oxidizing and reducing properties. It is considered that the sintering of Pt or Pd caused by the atmosphere change is reduced.
[0012]
Nd, Sm, or Gd is considered to increase the oxygen ion conductivity of the perovskite complex oxide as a whole by partially replacing Ce at the B site of the perovskite complex oxide. Therefore, it is considered that oxygen transfer is promoted between the atmospheric gas and the perovskite complex oxide crystal, the oxygen storage performance of Ce is further enhanced, and the sintering suppression of Pt or Pd is more effective. .
[0013]
Since Zr is inherently high in heat resistance, Zr replaces a part of the crystal lattice to improve the stability of the crystal structure and repeat the oxidizing and reducing atmosphere. It is thought to increase heat resistance.
Pt or Pd is considered to provide catalytic activity for exhaust gas purification as an inherent property.
[0014]
Such oxygen ion conductivity due to Nd, heat resistance due to Zr, and catalytic activity due to Pt are manifested by partial substitution of Ce at the B site of the perovskite complex oxide. It is considered that there is an optimum range in composition as limited by the present invention.
[0015]
The optimum range on the composition, the chemical formula: in ACe 1-xyz B 'x Zr y B " perovskite-type composite oxide represented by z O 3, an 0 <x <0.5, preferably 0. 05 <x <0.4, more preferably 0.05 <x <0.3, 0 <y <0.5, preferably 0.05 <y <0.4, more preferably 0. 1 <y <0.25, 0 <z ≦ 0.5, preferably 0.15 <z <0.5, and more preferably 0.1 <z <0.4.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The above formula: ACe 1-xyz B 'x Zr y B "z O 3 (A is at least one of Ba and Sr, B' is Nd, Sm, and at least one Gd, B" is, Pt And at least one of Pd, 0 <x <0.5, 0 <y <0.5, 0 <z ≦ 0.5, where 1> (x + y + z).) It can be manufactured by various methods.
For example, inorganic compounds such as nitrates and carbonates of elements Ba, Sr, Ce, Nd, Sm, Gd, Zr, Pt, and Pd contained in the perovskite complex oxide, or organic compounds such as alkoxides and acetylacetonates Can be manufactured by mixing at a predetermined ratio and then firing at a temperature of 600 to 1100 ° C. in an air atmosphere.
[0017]
Preferably, an aqueous solution containing the above-mentioned inorganic compound in a predetermined ratio is prepared, and then a precipitate is prepared by adjusting the pH of the aqueous solution by adding ammonia or the like, or an alcohol solution containing the above-mentioned organic compound in a predetermined ratio Then, precursors are prepared through a solution such that water is added to prepare a precipitate by hydrolysis, and these precursors are then fired to produce a perovskite complex oxide. This is because a perovskite complex oxide having a uniform composition is easily obtained through such a solution.
[0018]
The obtained perovskite complex oxide can be used as an exhaust gas purifying catalyst excellent in high temperature durability performance by adjusting the particle size by crushing or pulverizing if necessary.
In order to use such an exhaust gas purifying catalyst as a general honeycomb type catalyst, it is possible to carry the above-mentioned perovskite type complex oxide powder on a honeycomb base material by a wash coat or the like in a usual manner.
Hereinafter, the present invention will be described more specifically with reference to examples.
[0019]
【Example】
Example 1
24.38 g of barium nitrate Ba (NO 3 ) 2 , 24.306 g of cerium nitrate Ce (NO 3 ) 3 .6H 2 O, 4.21 g of gadolinium nitrate Gd (NO 3 ) 3 .6H 2 O, 4.9866 g Zirconium oxynitrate ZrO (NO 3 ) 2 · 2H 2 O, 4.8326 g of chloroplatinic acid H 2 PtCl 6 · 6H 2 O as raw materials, and these were added to 750 g of ion-exchanged water and stirred for 1 hour. An aqueous solution of these raw materials was prepared, and 15 g of a 28% aqueous ammonia solution was added to the aqueous solution and stirred for 2 hours. The obtained precipitate was dried in an air atmosphere at 120 ° C. for 12 hours and then calcined in an air atmosphere at 300 ° C. for 1 hour.
The calcined powder was pulverized and then calcined in an air atmosphere at 700 ° C. for 5 hours to obtain a perovskite complex oxide powder having a composition of BaCe 0.6 Gd o.1 Zr 0.2 Pt 0.1 O 3 .
[0020]
Example 2
4. BaCe as in Example 1 except that 4.5336 g of samarium nitrate Sm (NO 3 ) 3 .6H 2 O was used as a raw material instead of 4.21 g of gadolinium nitrate Gd (NO 3 ) 3 .6H 2 O. A perovskite complex oxide powder having a composition of 0.6 Sm o.1 Zr 0.2 Pt 0.1 O 3 was obtained.
[0021]
Example 3
In the same manner as in Example 1 except that 4.0895 g of neodymium nitrate Nd (NO 3 ) 3 .6H 2 O was used as a raw material instead of 4.21 g of gadolinium nitrate Gd (NO 3 ) 3 .6H 2 O. A perovskite complex oxide powder having a composition of 0.6 Nd o.1 Zr 0.2 Pt 0.1 O 3 was obtained.
[0022]
Example 4
BaCe 0.6 Nd o.1 in the same manner as in Example 3 except that 2.156 g of palladium nitrate Pd (NO 3 ) 3 was used instead of 4.8326 g of chloroplatinic acid H 2 PtCl 6 .6H 2 O. A perovskite complex oxide powder having a composition of Zr 0.2 Pd 0.1 O 3 was obtained.
[0023]
Example 5
Instead of 4.8326 g of chloroplatinic acid H 2 PtCl 6 .6H 2 O, 3.6245 g of chloroplatinic acid H 2 PtCl 6 .6H 2 O and 0.5375 g of palladium nitrate Pd (NO 3 ) 3 are used as raw materials. except that had got powder of perovskite-type composite oxide having a composition of BaCe 0.6 Nd o.1 Zr 0 .2 Pt 0.075 Pd 0.025
[0024]
Comparative Example 1
The composition of Ba 4 PtO 6 is the same as that of Example 1 except that 97.52 g of barium nitrate Ba (NO 3 ) 2 and 4.8326 g of chloroplatinic acid H 2 PtCl 6 .6H 2 O are used as raw materials. A composite oxide powder was obtained.
[0025]
Comparative Example 2
24.38 g of barium nitrate Ba (NO 3 ) 2 , 24.306 g of cerium nitrate Ce (NO 3 ) 3 .6H 2 O, 4.9866 g of zirconium oxynitrate ZrO (NO 3 ) 2 .2H 2 O, 9. A perovskite complex oxide powder having a composition of BaCe 0.6 Zr 0.2 Pt 0.2 O 3 was obtained in the same manner as in Example 1 except that 6652 g of chloroplatinic acid H 2 PtCl 6 · 6H 2 O was used as a raw material.
[0026]
Comparative Example 3
24.38 g of barium nitrate Ba (NO 3 ) 2 , 32.408 g of cerium nitrate Ce (NO 3 ) 3 .6H 2 O, 4.0895 g of neodymium nitrate Nd (NO 3 ) 3 .6H 2 O, 4.8326 g A perovskite complex oxide powder having a composition of BaCe 0.8 Nd 0.1 Pt 0.1 O 3 was obtained in the same manner as in Example 1 except that chloroplatinic acid H 2 PtCl 6 · 6H 2 O was used as a raw material.
[0027]
Comparative Example 4
24.38 g of barium nitrate Ba (NO 3 ) 2 , 28.357 g of cerium nitrate Ce (NO 3 ) 3 .6H 2 O, 4.9866 g of zirconium oxynitrate ZrO (NO 3 ) 2 .2H 2 O, 4. A perovskite complex oxide powder having a composition of BaCe 0.7 Zr 0.2 Nd 0.1 O 3 was obtained in the same manner as in Example 1 except that 0895 g of neodymium nitrate Nd (NO 3 ) 3 .6H 2 O was used as a raw material. .
[0028]
Examples of other perovskite type complex oxides Examples 1 to 5 and Comparative Examples 1 to 4 above are typical examples of different elements in the vicinity of the optimum composition of the perovskite type complex oxide, and examples for comparison. It is what I have listed. In addition to these examples, in order to grasp the effects of different compositions, the same raw materials used in the examples were used at different ratios to produce various perovskite complex oxides having different x, y, and z. The test was combined with the above example.
[0029]
-Endurance treatment-
Each of the above-mentioned various complex oxides was pressure-molded and then pulverized into granules having a diameter of 1 to 3 mm. Each obtained particulate matter is placed in a normal pressure flow-type endurance treatment device, and the ratio of air / fuel (A / F) is changed between 14 and 16 every minute. Under a changing atmosphere, a durability treatment was performed at 1000 ° C. for 5 hours with a total gas amount of 5 liters / minute.
[0030]
−Exhaust gas purification performance test−
Each perovskite type complex oxide before and after the above durability treatment was used as an exhaust gas purification catalyst, and 2 g of each granular material was put into an exhaust gas purification performance measuring device. While flowing at a gas volume of 15 liters / minute, the catalyst temperature was changed and NO and C 3 H 6 purification rates were measured.
[0032]
[0033]
-X-ray powder diffraction (XRD) evaluation-
FIG. 1 and FIG. 2 show XRD charts of the perovskite complex oxide powders obtained in Example 3 and Comparative Example 1 before and after the endurance treatment, respectively.
Moreover, the structure residual rate was calculated | required by the proportional calculation from the area of the spectrum which shows the highest peak on an XRD chart.
[0034]
-From the results-
(1) Stability of crystal structure From the XRD charts shown in FIG. 1 and FIG. 2, when the changes appearing in the XRD chart before and after the endurance of the powder of Example 3 and Comparative Example 1 are compared, While no change is seen, it can be seen that in Comparative Example 1, a considerable change has occurred.
Further, when the powder particles of Example 3 and Comparative Example 1 were observed with a transmission electron microscope, the powder particles of Example 3 showed no change in form before and after the durability treatment, but after the durability treatment. In the powder particles of Comparative Example 1, precipitation of Pt particles due to sintering was observed.
[0035]
Further, FIG. 4 shows that the structural stability of the perovskite complex oxide increases as the amount of Zr contained in the perovskite complex oxide increases.
From these, it can be seen that the perovskite complex oxide specified in the present invention has high durability performance, and the presence of Zr contributes to this durability performance.
[0036]
(2) High temperature durability performance Table 1 summarizes the 50% purification temperatures of NO and C 3 H 6 before and after the durability treatment for the catalysts of Examples 1 to 5 and Comparative Examples 1 to 4. From these results, it can be seen that there is a significant difference in the purification performance of NO and C 3 H 6 after the endurance treatment between the example and the comparative example.
[0037]
(3) Optimum range of x value Figure 3 shows that the purification performance of NO and C 3 H 6 is improved by substituting part of Ce at the B site of the perovskite type complex oxide with Gd. It shows that there is. The effect of improving the purification performance is that oxygen ion conductivity is increased by substituting part of Ce with Gd. On the other hand, when the amount of substitution increases, the amount of Ce decreases and the oxygen storage performance decreases. Therefore, it is considered that the x value has an optimum range.
[0038]
(4) Optimum range of y value FIG. 4 shows that the purification performance of C 3 H 6 is improved by substituting part of Ce at the B site of perovskite type complex oxide with Zr, and there is an optimum range of y value. It is shown that. The effect of improving the purification performance is that by replacing part of Ce with Zr, the inherent durability performance of Zr is exhibited. On the other hand, when the amount of substitution increases, the amount of Ce decreases and oxygen storage Since the performance decreases, it is considered that there is an optimum range for the y value.
[0039]
(5) Optimum range of z value Fig. 5 shows that the replacement performance of NO and C 3 H 6 is improved by substituting part of Ce at the B site of the perovskite complex oxide, but the increase in the amount of Pt The effect of shows that it saturates at a certain level. The effect of improving the purification performance is that by substituting part of Ce with Pt, the original purification performance of Pt is exhibited. On the other hand, when the amount of substitution increases, the amount of Ce decreases and oxygen storage occurs. Since performance decreases, it is considered that there is a certain limit to the performance improvement effect.
FIG. 5 also clearly shows the effect of the present invention that can reduce the amount of Pt, such that high exhaust gas purification performance is exhibited even in a composition region having a relatively small amount of Pt.
[0040]
(6) Thus, the present invention provides an exhaust gas purification catalyst having high durability performance by using a specific perovskite-type composite oxide. This durability performance includes oxygen storage performance, oxygen storage performance, Such a perovskite type complex oxide is considered to have an optimum compositional range as limited by the present invention because it is brought about by a balance of ion conductivity, stability of crystal structure, and catalytic activity.
[0041]
[Table 1]
【The invention's effect】
It is possible to provide a catalyst having excellent durability performance that can maintain the catalyst performance without deterioration even at a high temperature exceeding 1000 ° C.
[Brief description of the drawings]
FIG. 1 is an XRD chart comparing before and after endurance treatment of a perovskite complex oxide of the present invention.
FIG. 2 is an XRD chart comparing before and after endurance treatment of a perovskite complex oxide of a comparative example.
FIG. 3 is a graph showing fluctuations in catalyst purification performance when x value is changed.
FIG. 4 is a graph showing fluctuations in catalyst purification performance when the y value is changed.
FIG. 5 is a graph showing fluctuations in catalyst purification performance when the z value is changed.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001002575A JP3818062B2 (en) | 2001-01-10 | 2001-01-10 | Exhaust gas purification catalyst |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001002575A JP3818062B2 (en) | 2001-01-10 | 2001-01-10 | Exhaust gas purification catalyst |
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| JP2002204955A JP2002204955A (en) | 2002-07-23 |
| JP3818062B2 true JP3818062B2 (en) | 2006-09-06 |
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Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7576032B2 (en) | 2003-12-17 | 2009-08-18 | Daihatsu Motor Co., Ltd. | Catalyst composition |
| JP5106748B2 (en) | 2004-11-08 | 2012-12-26 | 株式会社キャタラー | Exhaust gas purification catalyst |
| EP1854538A4 (en) * | 2005-03-04 | 2011-06-08 | Daihatsu Motor Co Ltd | Catalyst composition |
| JP2006346603A (en) * | 2005-06-16 | 2006-12-28 | Cataler Corp | Catalyst composition |
| JP4465305B2 (en) * | 2005-06-16 | 2010-05-19 | 株式会社キャタラー | Exhaust gas purification catalyst |
| JP4979900B2 (en) * | 2005-06-16 | 2012-07-18 | 株式会社キャタラー | Exhaust gas purification catalyst |
| JP4855013B2 (en) * | 2005-08-18 | 2012-01-18 | 株式会社ノリタケカンパニーリミテド | Oxygen separation membrane and hydrocarbon oxidation reactor |
| JP5549258B2 (en) * | 2010-02-15 | 2014-07-16 | マツダ株式会社 | Exhaust gas purification catalyst |
| EP2954950B1 (en) | 2013-02-08 | 2020-06-17 | Umicore Shokubai Japan Co., Ltd. | Catalyst for purifying nox occlusion reduction-type exhaust gas and exhaust gas purification method using said catalyst |
| CN104689817B (en) * | 2014-12-12 | 2017-02-22 | 湖北航特科技有限责任公司 | Composite oxide catalyst for purification of vehicle tail gas and method for preparing composite oxide catalyst for purification of vehicle tail gas |
| US9527033B2 (en) * | 2015-01-23 | 2016-12-27 | Toyota Motor Engineering & Manufacturing North America, Inc. | Mixed metal oxide catalyst |
| EP3925688A4 (en) * | 2019-03-22 | 2022-11-02 | Murata Manufacturing Co., Ltd. | Exhaust gas purification catalyst and exhaust gas treatment equipment |
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