JP2003062465A - Catalyst - Google Patents
CatalystInfo
- Publication number
- JP2003062465A JP2003062465A JP2001258162A JP2001258162A JP2003062465A JP 2003062465 A JP2003062465 A JP 2003062465A JP 2001258162 A JP2001258162 A JP 2001258162A JP 2001258162 A JP2001258162 A JP 2001258162A JP 2003062465 A JP2003062465 A JP 2003062465A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- alumina
- palladium
- cerium
- present
- 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 87
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 53
- 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 52
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 44
- 238000002485 combustion reaction Methods 0.000 claims abstract description 11
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 abstract description 97
- 230000003197 catalytic effect Effects 0.000 abstract description 2
- 238000004140 cleaning Methods 0.000 abstract 2
- 239000000843 powder Substances 0.000 description 18
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 17
- 239000007789 gas Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 14
- 239000002002 slurry Substances 0.000 description 13
- 238000000746 purification Methods 0.000 description 12
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 10
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 9
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 9
- 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 6
- 239000002245 particle Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 5
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 5
- QBEGYEWDTSUVHH-UHFFFAOYSA-P diazanium;cerium(3+);pentanitrate Chemical compound [NH4+].[NH4+].[Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O QBEGYEWDTSUVHH-UHFFFAOYSA-P 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000011812 mixed powder Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 2
- 150000001785 cerium compounds Chemical class 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 150000002941 palladium compounds Chemical class 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910000887 (NH4)2Ce(NO3)5·4H2O Inorganic materials 0.000 description 1
- BWLBGMIXKSTLSX-UHFFFAOYSA-N 2-hydroxyisobutyric acid Chemical compound CC(C)(O)C(O)=O BWLBGMIXKSTLSX-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 101100321669 Fagopyrum esculentum FA02 gene Proteins 0.000 description 1
- LHYHHJWPQYWOFM-UHFFFAOYSA-N N.N.[Ce+3].[Ce+3] Chemical compound N.N.[Ce+3].[Ce+3] LHYHHJWPQYWOFM-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- -1 acetonate Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 239000012693 ceria precursor Substances 0.000 description 1
- PYPNFSVOZBISQN-LNTINUHCSA-K cerium acetylacetonate Chemical compound [Ce+3].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O PYPNFSVOZBISQN-LNTINUHCSA-K 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- UGWHPQNZVGJHMU-UHFFFAOYSA-Q triazanium trinitrate Chemical compound [NH4+].[NH4+].[NH4+].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O UGWHPQNZVGJHMU-UHFFFAOYSA-Q 0.000 description 1
Landscapes
- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、高い燃焼作用を奏
する触媒に関し、特には、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中の炭化水素を燃焼浄化する
ための排気ガス浄化触媒に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst having a high combustion effect, and more particularly to an exhaust gas purifying catalyst for burning and purifying hydrocarbons in exhaust gas discharged from an internal combustion engine such as an automobile engine. .
【０００２】[0002]
【従来の技術】自動車用エンジン等の内燃機関から排出
される排気ガスには、一酸化炭素(ＣＯ)、炭化水素(Ｈ
Ｃ)、窒素酸化物(ＮＯX)等が含まれ、これらの有害物質
は、一般に、白金、金、パラジウム、ルテニウム、ロジ
ウム等の貴金属を触媒成分とする排気ガス浄化用触媒に
よって浄化される。2. Description of the Related Art Exhaust gas emitted from an internal combustion engine such as an automobile engine contains carbon monoxide (CO), hydrocarbon (H
C), nitrogen oxides (NO x ), etc. are contained, and these harmful substances are generally purified by an exhaust gas purifying catalyst containing a precious metal such as platinum, gold, palladium, ruthenium, rhodium as a catalyst component.
【０００３】この排気ガス浄化用触媒は、通常、金属酸
化物の担体に上記の触媒成分を担持して構成されるが、
これらの有害物質の浄化反応を効率的に促進するために
は、触媒成分が排気ガスとの高い接触面積を呈するよう
に、担体上に触媒成分が高分散に担持されることが重要
である。したがって、担体は、高い比表面積を有するこ
とが必要であり、そして、この高い比表面積は、触媒が
使用される条件下で経時的に維持されることが必要であ
る。This exhaust gas purifying catalyst is usually composed of a metal oxide carrier carrying the above catalyst components.
In order to efficiently promote the purification reaction of these harmful substances, it is important that the catalyst component is supported in high dispersion on the carrier so that the catalyst component exhibits a high contact area with exhaust gas. Therefore, the support needs to have a high specific surface area, and this high specific surface area needs to be maintained over time under the conditions in which the catalyst is used.
【０００４】例えば、自動車用エンジンの排気ガス浄化
用触媒の場合、常温と約１０００℃の間で温度が繰り返
して変動し、かつ比較的ＨＣとＣＯの濃度が高くてＯ2
濃度が低い還元性雰囲気と、比較的ＨＣとＣＯの濃度が
低くてＯ2濃度が高い酸化性雰囲気が繰り返される条件
下で、この高い比表面積が維持される必要がある。For example, in the case of a catalyst for purifying exhaust gas of an automobile engine, the temperature repeatedly fluctuates between room temperature and about 1000 ° C., and the concentration of HC and CO is relatively high, and O 2
It is necessary to maintain this high specific surface area under conditions in which a reducing atmosphere having a low concentration and an oxidizing atmosphere having a relatively low HC and CO concentrations and a high O 2 concentration are repeated.
【０００５】したがって、担体には、こうした厳しい条
件下でも耐久性を有する比表面積が高いアルミナ、シリ
カ、ジルコニア等の金属酸化物の材料が選択され、通
常、約１８０ｍ2／ｇの比表面積を有するγ-アルミナが
使用される。このγ-アルミナは、現状では、高い比表
面積と優れた耐久性を最もバランス良く有する担体材料
とされている。Therefore, a metal oxide material such as alumina, silica or zirconia having a high specific surface area which is durable under such severe conditions is selected for the carrier, and usually has a specific surface area of about 180 m 2 / g. γ-alumina is used. At present, this γ-alumina is regarded as a carrier material having a high specific surface area and excellent durability in the best balance.
【０００６】一方、触媒成分に使用される貴金属は、そ
れぞれ固有の反応活性を有し、パラジウムは高い燃焼作
用を奏することができる。このため、パラジウムは、一
般に、ＨＣの燃焼浄化を促進させるために排気ガス浄化
用触媒に含められる。ところで、セリウムは、酸素スト
レージ能を有するといった、金属酸化物の中では特有の
性質を有することが知られており、この性質を排気ガス
浄化用触媒に利用することが検討されている。例えば、
特開平６−１１４２６４号では、アルミナに担持された
セリウム及びジルコニウムの両酸化物を充分に複合化
し、このアルミナ粉末にパラジウムが担持された排気ガ
ス浄化用触媒が提案されている。On the other hand, the noble metals used as the catalyst component each have a unique reaction activity, and palladium can exhibit a high combustion action. Therefore, palladium is generally included in the exhaust gas purifying catalyst in order to promote combustion purification of HC. By the way, cerium is known to have a unique property among metal oxides, such as having an oxygen storage capacity, and utilization of this property for an exhaust gas purification catalyst has been studied. For example,
Japanese Unexamined Patent Publication No. 6-114264 proposes an exhaust gas purifying catalyst in which both oxides of cerium and zirconium supported on alumina are sufficiently complexed and palladium is supported on the alumina powder.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、このよ
うな従来技術の触媒では、パラジウムは、セリウム及び
ジルコニウムの両酸化物上に担持されるため、担体の比
表面積が実質的に小さくなってパラジウムは高分散に担
持されず、パラジウムの触媒活性が低下する恐れがあっ
た。また、セリウムの特性を排気ガス浄化用触媒に利用
する従来の技術には、一層の改良の余地があった。した
がって、本発明は、担体にパラジウムを高分散に担持し
ながら、セリウムの特性を効果的に利用し、それによっ
て、ＨＣ浄化性能が顕著に高められたパラジウム含有触
媒を提供することを目的とする。However, in such a prior art catalyst, since palladium is supported on both oxides of cerium and zirconium, the specific surface area of the carrier is substantially reduced and palladium is There is a possibility that the catalyst may not be supported in a high dispersion and the catalytic activity of palladium may decrease. In addition, there is room for further improvement in the conventional technology that utilizes the characteristics of cerium in an exhaust gas purification catalyst. Therefore, it is an object of the present invention to provide a palladium-containing catalyst in which the characteristics of cerium are effectively used while supporting palladium on a carrier in a highly dispersed manner, thereby significantly improving the HC purification performance. .
【０００８】[0008]
【課題を解決するための手段】上記目的は、アルミナ上
にセリウム(Ｃｅ)とパラジウム(Ｐｄ)が原子状態で担持
されたことを特徴とする触媒によって達成される。即
ち、本発明の触媒は、ＣｅとＰｄが、アルミナ上で明確
な形態を有する粒子状態で存在するのではなく、Ｃｅと
Ｐｄの双方が、微細な原子状態でアルミナ上に存在する
ことを特徴とする触媒である。The above object can be achieved by a catalyst characterized in that cerium (Ce) and palladium (Pd) are supported in an atomic state on alumina. That is, the catalyst of the present invention is characterized in that Ce and Pd do not exist in the state of particles having a well-defined morphology on alumina, but both Ce and Pd exist on the alumina in a fine atomic state. Is a catalyst.
【０００９】こうした本発明の触媒は、顕著に高いＨＣ
燃焼作用を奏することができるが、この理由は、Ｃｅと
Ｐｄの双方が微細な原子状態でアルミナ上に存在するこ
とで、アルミナの高い比表面積が、Ｐｄの高分散をもた
らすためと考えられる。もう１つの理由として、必ずし
も明らかではないが、後述の実施例で示すように、Ｃｅ
とＰｄの双方が微細な原子状態でアルミナ上に存在する
ことで、ＰｄはＣｅから酸素を獲得しやすくなり、ま
た、Ｐｄは、Ｃｅの作用によって酸素との結合が弱くな
り、したがって、ＰｄからＨＣに酸素を供与することが
促進されるためと推定される。Such a catalyst of the present invention has a significantly high HC.
Although it is possible to exert a combustion action, it is considered that the reason is that both Ce and Pd exist on the alumina in a fine atomic state, so that the high specific surface area of the alumina causes a high dispersion of Pd. As another reason, although not always clear, as shown in the examples below, Ce
Since both Pd and Pd are present on the alumina in a fine atomic state, Pd easily acquires oxygen from Ce, and Pd weakens the bond with oxygen due to the action of Ce. It is presumed that the donation of oxygen to HC is promoted.
【００１０】また、別な局面において、本発明は、アル
ミナ上にＣｅとＰｄが担持されてなる触媒であって、ア
ルミナとＣｅとＰｄの合計質量を基準に、Ｃｅが０.１
〜１０質量％含まれ、かつＣｅ／Ｐｄのモル比が０.０
４〜４であることを特徴とする触媒である。こうした本
発明の触媒が、高いＨＣ燃焼作用を奏することができる
理由は、かかる数値範囲において、上記のＰｄからＨＣ
への酸素供与が最適化されるものと推定される。In another aspect, the present invention is a catalyst comprising Ce and Pd supported on alumina, wherein Ce is 0.1 based on the total mass of alumina, Ce and Pd.
10 to 10% by mass, and the Ce / Pd molar ratio is 0.0.
It is a catalyst characterized by being 4-4. The reason why such a catalyst of the present invention can exhibit a high HC combustion action is that the above Pd to HC
It is estimated that the oxygen supply to the oxygen is optimized.
【００１１】[0011]
【発明の実施の形態】本発明の触媒は、アルミナ上にＣ
ｅとＰｄが原子状態で担持されてなる触媒である。この
アルミナは、限定されるものではないが、約１８０ｍ2
／ｇのような高い比表面積を有するγ-アルミナ粉末が
適切である。このアルミナ上にＣｅとＰｄを原子状態で
担持するには、例えば、Ｃｅ源として硝酸二アンモニウ
ムセリウム、硝酸セリウム、セリウムアセチルアセトナ
ートのようなセリウム化合物を用い、Ｐｄ源として、硝
酸パラジウム、パラジウムアセチルアセトナートのよう
なパラジウム化合物を用い、例えば、これらの化合物を
適切な溶媒に溶かし、この溶液にγ-アルミナを分散さ
せ、得られたスラリーを濃縮乾固し、次いで、４００〜
８００℃の大気雰囲気中で数時間焼成することにより行
うことができる。BEST MODE FOR CARRYING OUT THE INVENTION The catalyst of the present invention comprises C on alumina.
It is a catalyst in which e and Pd are supported in an atomic state. This alumina may include, but is not limited to, about 180 m 2
Γ-alumina powder having a high specific surface area such as / g is suitable. In order to support Ce and Pd on the alumina in an atomic state, for example, a cerium compound such as diammonium cerium nitrate, cerium nitrate or cerium acetylacetonate is used as the Ce source, and palladium nitrate or palladium acetyl is used as the Pd source. Using a palladium compound such as acetonate, for example, these compounds are dissolved in a suitable solvent, γ-alumina is dispersed in this solution, the resulting slurry is concentrated to dryness, then 400-
It can be performed by firing in an air atmosphere at 800 ° C. for several hours.
【００１２】また、別な局面において、本発明は、アル
ミナ上にＣｅとＰｄが担持されてなる触媒であって、ア
ルミナとＣｅとＰｄの合計質量を基準に、Ｃｅが０.１
〜１０質量％含まれ、かつＣｅ／Ｐｄのモル比が０.０
４〜４であることを特徴とする触媒であり、より好まし
くは、アルミナとＣｅとＰｄの合計質量を基準にＣｅが
０.５〜５質量％含まれ、かつＣｅ／Ｐｄのモル比が０.
２〜３の触媒である。[0012] In another aspect, the present invention is a catalyst comprising Ce and Pd supported on alumina, wherein Ce is 0.1 based on the total mass of alumina, Ce and Pd.
10 to 10% by mass, and the Ce / Pd molar ratio is 0.0.
The catalyst is characterized in that it is 4 to 4, more preferably 0.5 to 5 mass% of Ce based on the total mass of alumina, Ce and Pd, and the molar ratio of Ce / Pd is 0. .
2-3 catalysts.
【００１３】アルミナ上にＣｅとＰｄがかかる特定の割
合で担持される触媒は、例えば、上記の方法において、
アルミナ粉末、セリウム化合物、及びパラジウム化合物
を所定量で用いることで得ることができる。The catalyst in which Ce and Pd are supported on alumina at such a specific ratio is, for example, in the above-mentioned method,
It can be obtained by using alumina powder, a cerium compound, and a palladium compound in predetermined amounts.
【００１４】図１は、このようにして得られる本発明の
触媒を模式的に示すものであるが、高い比表面積を有す
るアルミナの上にＣｅとＰｄが原子状態で担持されるこ
とで、Ｐｄはアルミナ上で高分散に存在することができ
る。図２は、セリアの上にＰｄが担持された従来技術の
触媒を模式的に示すものであるが、セリアはアルミナに
比較して比表面積が小さくかつ耐久性が劣るため、Ｐｄ
を高分散に担持することが困難である。FIG. 1 schematically shows the catalyst of the present invention thus obtained. Ce and Pd are supported in an atomic state on alumina having a high specific surface area to obtain Pd. Can be highly dispersed on the alumina. FIG. 2 schematically shows a prior art catalyst in which Pd is supported on ceria. Ceria has a smaller specific surface area and inferior durability as compared with alumina.
Is difficult to support in a high dispersion.
【００１５】図３は、セリア−ジルコニア複合酸化物の
上にＰｄが担持された従来技術の触媒を模式的に示すも
のであるが、セリア−ジルコニア複合酸化物は、セリア
よりも高い耐久性を有するものの、γ-アルミナよりも
一般に比表面積が低いため、Ｐｄを高分散に担持するこ
とが困難である。なお、これらの図は、あくまで本発明
を説明するためのモデル図であって、本発明を限定する
ものではない。以下、実施例によって本発明をより具体
的に説明する。FIG. 3 schematically shows a prior art catalyst in which Pd is supported on a ceria-zirconia composite oxide. The ceria-zirconia composite oxide has higher durability than ceria. However, since it has a specific surface area generally smaller than that of γ-alumina, it is difficult to support Pd in high dispersion. It should be noted that these figures are merely model diagrams for explaining the present invention and do not limit the present invention. Hereinafter, the present invention will be described more specifically with reference to Examples.
【００１６】[0016]
【実施例】実施例１
γ-アルミナ粉末１９.６ｇを１００ｃｃのイオン交換水
に分散させ、得られたスラリーに、硝酸二アンモニウム
セリウム(ＮＨ4)2Ｃｅ(ＮＯ3)5をＣｅ０.０２ｇ相当量
で添加し、このスラリーを濃縮乾固し、乾燥と粉砕の
後、４５０℃×２時間の焼成を行った。得られた粉末を
１００ｃｃのイオン交換水に分散させ、このスラリーに
硝酸パラジウムをＰｄ０.４ｇ相当量で添加し、このス
ラリーを濃縮乾固し、乾燥と粉砕の後、４５０℃×２時
間の焼成を行い、本発明の触媒Ａを得た。Example 1 19.6 g of γ-alumina powder was dispersed in 100 cc of ion-exchanged water, and the obtained slurry was mixed with cerium diammonium cerium (NH 4 ) 2 Ce (NO 3 ) 5 corresponding to 0.02 g of Ce. The slurry was concentrated to dryness, dried and pulverized, and then calcined at 450 ° C. for 2 hours. The obtained powder was dispersed in 100 cc of ion-exchanged water, palladium nitrate was added to the slurry in an amount of 0.4 g equivalent to Pd, the slurry was concentrated to dryness, dried and ground, and then baked at 450 ° C. for 2 hours. Then, the catalyst A of the present invention was obtained.
【００１７】実施例２〜７
実施例１におけるγ-アルミナ粉末に対する硝酸二アン
モニウムセリウムを変えた以外は実施例１と同様にし
て、表１に示すＣｅ量（アルミナとＣｅとＰｄの合計質
量を基準）とＣｅ／Ｐｄのモル比を有する本発明の触媒
Ｂ〜Ｇを得た。Examples 2 to 7 In the same manner as in Example 1 except that cerium diammonium nitrate was changed with respect to the γ-alumina powder in Example 1, the Ce amounts shown in Table 1 (total mass of alumina, Ce and Pd was calculated as follows). The catalysts B to G of the present invention having a molar ratio of (standard) and Ce / Pd were obtained.
【００１８】実施例８
γ-アルミナ粉末１９.４ｇを１００ｃｃのイオン交換水
に分散させ、得られたスラリーに、硝酸セリウムＣｅ
(ＮＯ3)3をＣｅ０.２ｇ相当量で添加し、このスラリー
を濃縮乾固し、乾燥と粉砕の後、４５０℃×２時間の焼
成を行った。得られた粉末を１００ｃｃのイオン交換水
に分散させ、このスラリーに硝酸パラジウムをＰｄ０.
４ｇ相当量で添加し、このスラリーを濃縮乾固し、乾燥
と粉砕の後、４５０℃×２時間の焼成を行い、本発明の
触媒Ｈを得た。Example 8 19.4 g of γ-alumina powder was dispersed in 100 cc of ion-exchanged water, and the resulting slurry was mixed with cerium nitrate Ce.
(NO 3 ) 3 was added in an amount equivalent to 0.2 g of Ce, the slurry was concentrated to dryness, dried and pulverized, and then baked at 450 ° C. for 2 hours. The obtained powder was dispersed in 100 cc of ion-exchanged water, and palladium nitrate was added to this slurry in an amount of Pd 0.
An amount of 4 g was added, the slurry was concentrated to dryness, dried and pulverized, and then calcined at 450 ° C. for 2 hours to obtain a catalyst H of the present invention.
【００１９】実施例９
γ-アルミナ粉末１９.４ｇを１００ｃｃのイオン交換水
に分散させ、得られたスラリーに、硝酸二アンモニウム
セリウムのＣｅ０.２ｇ相当量と硝酸パラジウムのＰｄ
０.４ｇ相当量を添加し、このスラリーを濃縮乾固し、
乾燥と粉砕の後、４５０℃×２時間の焼成を行い、本発
明の触媒Ｉを得た。Example 9 19.4 g of γ-alumina powder was dispersed in 100 cc of ion-exchanged water, and 0.2 g of Ce ammonium diammonium nitrate equivalent to Pd of palladium nitrate was added to the obtained slurry.
0.4 g equivalent amount was added, the slurry was concentrated to dryness,
After drying and pulverizing, calcination was performed at 450 ° C. for 2 hours to obtain the catalyst I of the present invention.
【００２０】実施例１０
実施例９における硝酸二アンモニウムセリウムを硝酸セ
リウムに代えた以外は実施例９と同様にして、本発明の
触媒Ｊを得た。Example 10 A catalyst J of the present invention was obtained in the same manner as in Example 9 except that the cerium diammonium nitrate in Example 9 was replaced with cerium nitrate.
【００２１】比較例１
実施例１における硝酸二アンモニウムセリウムを添加し
ない以外は実施例１と同様にして、表１に示す比較用の
触媒ａを得た。Comparative Example 1 Comparative catalyst a shown in Table 1 was obtained in the same manner as in Example 1 except that cerium diammonium nitrate was not added.
【００２２】比較例２
ミリングによって平均粒子径１μｍ以下に微細化したセ
リア粉末１９.６ｇを１００ｃｃのイオン交換水に分散
させ、得られたスラリーに、硝酸パラジウムをＰｄ０.
４ｇ相当量で添加し、このスラリーを濃縮乾固し、乾燥
と粉砕の後、４５０℃×２時間の焼成を行い、表２に示
す比較用の触媒ｂを得た。COMPARATIVE EXAMPLE 2 19.6 g of ceria powder finely divided into particles having an average particle size of 1 μm or less by milling was dispersed in 100 cc of ion-exchanged water, and palladium nitrate was added to the obtained slurry in an amount of Pd.
4 g equivalent amount was added, the slurry was concentrated to dryness, dried and pulverized, and then calcined at 450 ° C. for 2 hours to obtain a comparative catalyst b shown in Table 2.
【００２３】比較例３
セリア粉末とジルコニア粉末をＣｅ／Ｚｒ＝４５／５５
のモル比で混合し、ミリングによって平均粒子径１μｍ
以下に微細化したセリア−ジルコニア混合粉末を調製
し、比較例２におけるセリア粉末をこの混合粉末に代え
た以外は比較例２と同様にして、表２に示す比較用の触
媒ｃを得た。Comparative Example 3 Ceria powder and zirconia powder were mixed with Ce / Zr = 45/55.
The average particle size is 1μm
A finely divided ceria-zirconia mixed powder was prepared below, and a comparative catalyst c shown in Table 2 was obtained in the same manner as in Comparative Example 2 except that this mixed powder was used instead of the ceria powder in Comparative Example 2.
【００２４】比較例４
セリア粉末とジルコニア粉末とγ-アルミナ粉末をＣｅ
／Ｚｒ／Ａｌ＝１／１／２のモル比で混合し、ミリング
によって平均粒子径１μｍ以下に微細化したセリア−ジ
ルコニア−アルミナ混合粉末を調製し、比較例２におけ
るセリア粉末をこの混合粉末に代えた以外は比較例２と
同様にして、表２に示す比較用の触媒ｄを得た。Comparative Example 4 Ceria powder, zirconia powder, and γ-alumina powder were mixed with Ce.
/ Zr / Al = 1/1/2 was mixed, and milled to prepare a ceria-zirconia-alumina mixed powder having an average particle size of 1 μm or less. The ceria powder in Comparative Example 2 was mixed into this mixed powder. The catalyst d for comparison shown in Table 2 was obtained in the same manner as in Comparative Example 2 except that it was replaced.
【００２５】−触媒性能評価−
上記の実施例の触媒Ａ〜Ｊ、及び比較例の触媒ａ〜ｄ
を、それぞれ圧縮・解砕して直径１〜２ｍｍのペレット
に形成し、これらの触媒各２ｇを、実験室用の排気ガス
浄化性能評価装置の反応管内部に設置した。次いで、下
記のモデル雰囲気ガスを流通させ、触媒床温度を２０℃
／分の速度で昇温させながら、各温度におけるＣＨ4の
浄化率を測定した。これらの結果を表１〜２と図４〜５
にまとめて示す。
ガス組成：
１０００ｐｐｍＣＨ4 ＋ ８００ｐｐｍＮＯ＋０.２％Ｃ
Ｏ＋１０.０％ＣＯ2 ＋ ４.０％Ｏ2 ＋１０.０％Ｈ2Ｏ
（残余：窒素）-Catalyst Performance Evaluation-Catalysts A to J of the above Examples and catalysts a to d of Comparative Examples
Were respectively compressed and crushed to form pellets having a diameter of 1 to 2 mm, and 2 g of each of these catalysts was placed inside the reaction tube of an exhaust gas purification performance evaluation device for a laboratory. Then, the following model atmosphere gas is circulated and the catalyst bed temperature is set to 20 ° C.
The rate of purification of CH 4 at each temperature was measured while increasing the temperature at a rate of / min. These results are shown in Tables 1-2 and FIGS.
Are shown together. Gas composition: 1000ppm CH 4 + 800ppm NO + 0.2% C
O + 10.0% CO 2 + 4.0% O 2 + 10.0% H 2 O
(Remainder: nitrogen)
【００２６】これらの結果から、ＣＨ4の浄化に関し、
触媒中に含まれるセリウム含有量として０.１〜１０質
量％の範囲の中に最適値が存在することが分かる。ま
た、セリア前駆体溶液を用いて調製した本発明の触媒
は、セリア粉末を用いて調製した比較例の触媒よりも、
顕著にＣＨ4浄化性能が高いことが分かる。From these results, regarding the purification of CH 4 ,
It can be seen that the optimum value exists in the range of 0.1 to 10% by mass as the cerium content contained in the catalyst. Further, the catalyst of the present invention prepared by using the ceria precursor solution, than the catalyst of the comparative example prepared by using ceria powder,
It can be seen that the CH 4 purification performance is remarkably high.
【００２７】[0027]
【表１】 [Table 1]
【００２８】[0028]
【表２】 [Table 2]
【００２９】−セリウムの形態評価−
上記の実施例の各触媒Ａ〜Ｊについて、粉末Ｘ線回折
(ＸＲＤ)により結晶構造解析を行った。図６は、触媒Ｃ
についての回折パターンを示すものであるが、この回折
パターンから分かるように、回折ピークはγ-アルミナ
のみに対応し、Ｃｅ酸化物の回折ピークは現れていな
い。この他の実施例の触媒も同様にγ-アルミナのみの
回折ピークを示した。このことは、本発明の触媒に含ま
れるセリウムは、Ｘ線の回折パターンが生じる大きさで
存在しないか、又はアモルファス状態で存在することを
示すものと考えられる。-Evaluation of morphology of cerium-Powder X-ray diffraction of each of the catalysts A to J of the above-mentioned examples
The crystal structure was analyzed by (XRD). FIG. 6 shows the catalyst C
As shown in the diffraction pattern, the diffraction peak corresponds to γ-alumina only and the Ce oxide diffraction peak does not appear. The catalysts of the other examples also showed the diffraction peak of γ-alumina only. This is considered to indicate that the cerium contained in the catalyst of the present invention does not exist in a size in which an X-ray diffraction pattern occurs or exists in an amorphous state.
【００３０】一方、触媒Ａ〜Ｊを、透過型電子顕微鏡
(ＴＥＭ)によって分解能１ｎｍの高倍率で観察したとこ
ろ、いずれの触媒についてもγ-アルミナ粒子のみが観
察され、γ-アルミナに担持されたＣｅとＰｄは、電子
顕微鏡像からは観察されなかった。しかしながら、電子
顕微鏡像の観察と同時にエネルギー分散型Ｘ線分光分析
(ＥＤＸ)によって、電子顕微鏡像の各所の元素分析をし
たところ、γ-アルミナに電子線を照射した直径約１ｎ
ｍのスポット的な領域のいずれの箇所にも、Ａｌと同時
にＣｅとＰｄが常に分析され、その分析されたＡｌ／Ｃ
ｅ／Ｐｄのモル比は、触媒調製の原料からのモル比と実
質的に同等であった。On the other hand, the catalysts A to J were measured by a transmission electron microscope.
When observed by (TEM) at a high magnification with a resolution of 1 nm, only γ-alumina particles were observed for all catalysts, and Ce and Pd supported on γ-alumina were not observed from an electron microscope image. However, at the same time as observing electron microscope images, energy dispersive X-ray spectroscopy
Elemental analysis of each part of the electron microscope image by (EDX) showed that γ-alumina was irradiated with an electron beam and the diameter was about 1 n.
Ce and Pd are always analyzed at the same time as Al in any spot-like area of m, and the analyzed Al / C
The molar ratio of e / Pd was substantially equivalent to the molar ratio from the raw materials for catalyst preparation.
【００３１】これらのＸＲＤ、ＴＥＭ、ＥＤＸの結果
は、少なくとも直径約１ｎｍ未満の領域内に(Ｃｅ原子
半径：約０.１０ｎｍ、Ｐｄ原子半径：約０.１４ｎ
ｍ)、ＣｅとＰｄが均等に存在すること、言い換える
と、本発明の触媒では、ＣｅとＰｄが、実質的に原子状
態で相互が近傍に位置してアルミナ上に担持されている
ことを示すものと考えられる。The results of these XRD, TEM, and EDX show that at least in the region of less than about 1 nm in diameter (Ce atomic radius: about 0.10 nm, Pd atomic radius: about 0.14 n).
m), Ce and Pd are evenly present, in other words, the catalyst of the present invention shows that Ce and Pd are supported on alumina in a substantially atomic state in the vicinity of each other. It is considered to be a thing.
【００３２】−パラジウムの酸化状態分析−
Ｘ線光電子分光分析(ＸＰＳ)によって、触媒Ｃ、触媒
Ｈ、触媒ａ、触媒ｃについてパラジウムの３ｄ軌道電子
の結合エネルギーを測定した。この結果を表３に示す。
表３に示した結果より、セリウムを１.０質量％含む本
発明の触媒Ｃと触媒Ｈでは、セリウムを含まない比較例
の触媒ａ及びセリウムを多量に含む触媒ｃよりもパラジ
ウムの３ｄ軌道電子の結合エネルギーが低く、セリウム
の存在がパラジウムの酸化状態に影響を及ぼすことが明
らかに分かる。-Analysis of Palladium Oxidation State-The binding energy of 3d orbital electrons of palladium was measured for catalyst C, catalyst H, catalyst a and catalyst c by X-ray photoelectron spectroscopy (XPS). The results are shown in Table 3.
From the results shown in Table 3, in the catalyst C and the catalyst H of the present invention containing 1.0% by mass of cerium, 3d orbital electrons of palladium were higher than those of the catalyst a of Comparative Example containing no cerium and the catalyst c containing a large amount of cerium. The binding energy of is low and it is clear that the presence of cerium affects the oxidation state of palladium.
【００３３】また、本発明の触媒では、パラジウムの３
ｄ軌道電子が低い結合エネルギーを呈していることは、
セリウムを少量で含む本発明の触媒では、パラジウムは
金属に近い状態で存在することを示すものである。この
金属に近い状態で存在すること、及びＣｅとＰｄが実質
的に原子状態でγ-アルミナに担持されていることを照
らし合わせると、上記の本発明の触媒が高いＨＣ燃焼作
用を奏する理由は、以下のように推察される。Further, in the catalyst of the present invention, palladium 3
The low binding energy of d-orbital electrons means that
The catalyst of the present invention containing a small amount of cerium shows that palladium exists in a state close to that of metal. Considering that it exists in a state close to this metal and that Ce and Pd are supported on γ-alumina in a substantially atomic state, the reason why the catalyst of the present invention exhibits a high HC combustion action is , Is inferred as follows.
【００３４】１つの理由として、高い比表面積のγ-ア
ルミナの表面全体にＰｄが高分散に担持され、Ｐｄと排
気ガスとの接触面積が高いためと考えられる。もう１つ
の理由として、次のことが推察される。パラジウムは、
近傍に存在するセリウムの作用で酸素との結合が弱くな
り、また、高い酸素ストレージ能を有するセリウムがパ
ラジウムの近傍に存在することで、パラジウムは酸素を
獲得しやすくなる。この酸素は、パラジウムとの結合が
弱いために可燃成分のＨＣに供与されやすく、したがっ
て、触媒の燃焼作用が全体として高くなる。この作用
は、アルミナにパラジウムとセリウムが原子状で担持さ
れることで顕著となり、また、本発明で特定する範囲の
量でアルミナとパラジウムとセリウムが存在するとき
に、最適化されるものと推察される。It is considered that one reason is that Pd is highly dispersed and supported on the entire surface of γ-alumina having a high specific surface area, and the contact area between Pd and exhaust gas is high. The following can be inferred as another reason. Palladium is
The action of cerium existing in the vicinity weakens the bond with oxygen, and the presence of cerium having a high oxygen storage capacity in the vicinity of palladium facilitates the acquisition of oxygen by palladium. Since this oxygen has a weak bond with palladium, it is easily donated to HC, which is a combustible component, and therefore, the combustion action of the catalyst is increased as a whole. This effect becomes remarkable when palladium and cerium are atomically supported on alumina, and it is presumed that it will be optimized when alumina, palladium and cerium are present in the amounts specified in the present invention. To be done.
【００３５】[0035]
【表３】 [Table 3]
【００３６】[0036]
【発明の効果】ＨＣ浄化性能が顕著に高められた触媒を
提供することができる。EFFECTS OF THE INVENTION It is possible to provide a catalyst whose HC purification performance is remarkably enhanced.
【図１】本発明の触媒を例示する模式図である。FIG. 1 is a schematic view illustrating a catalyst of the present invention.
【図２】従来技術の触媒を例示する模式図である。FIG. 2 is a schematic diagram illustrating a prior art catalyst.
【図３】従来技術の触媒を例示する模式図である。FIG. 3 is a schematic diagram illustrating a prior art catalyst.
【図４】ＣＨ4浄化性能を比較したグラフである。FIG. 4 is a graph comparing CH 4 purification performances.
【図５】ＣＨ4浄化性能を比較したグラフである。FIG. 5 is a graph comparing CH 4 purification performances.
【図６】本発明の触媒のＸＲＤチャートである。FIG. 6 is an XRD chart of the catalyst of the present invention.
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 3G091 AB02 BA15 GB00W GB10X 4D048 AA18 AB01 BA03X BA19X BA31X BB01 4G069 AA03 AA08 BA01A BA01B BC43A BC43B BC72A BC72B CA03 CA07 CA15 DA06 EA02Y EC25 FA02 FB14 ─────────────────────────────────────────────────── ─── Continued front page F-term (reference) 3G091 AB02 BA15 GB00W GB10X 4D048 AA18 AB01 BA03X BA19X BA31X BB01 4G069 AA03 AA08 BA01A BA01B BC43A BC43B BC72A BC72B CA03 CA07 CA15 DA06 EA02Y EC25 FA02 FB14
Claims (4)
持されたことを特徴とする触媒。1. A catalyst comprising Ce and Pd supported in an atomic state on alumina.
る触媒であって、アルミナとＣｅとＰｄの合計質量を基
準に、Ｃｅが０.１〜１０質量％含まれ、かつＣｅ／Ｐ
ｄのモル比が０.０４〜４であることを特徴とする触
媒。2. A catalyst comprising Ce and Pd supported on alumina, wherein Ce is contained in an amount of 0.1 to 10 mass% based on the total mass of alumina, Ce and Pd, and Ce / P.
A catalyst having a molar ratio of d of 0.04 to 4.
に、Ｃｅが０.５〜５質量％含まれ、かつＣｅ／Ｐｄの
モル比が０.２〜３である請求項２に記載の触媒。3. The Ce content of 0.5 to 5 mass% based on the total mass of alumina, Ce and Pd, and the Ce / Pd molar ratio of 0.2 to 3. catalyst.
媒を含んでなる内燃機関の排気ガス浄化用触媒。4. A catalyst for purifying exhaust gas of an internal combustion engine, which comprises the catalyst according to any one of claims 1 to 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001258162A JP2003062465A (en) | 2001-08-28 | 2001-08-28 | Catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001258162A JP2003062465A (en) | 2001-08-28 | 2001-08-28 | Catalyst |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2003062465A true JP2003062465A (en) | 2003-03-04 |
Family
ID=19085730
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001258162A Pending JP2003062465A (en) | 2001-08-28 | 2001-08-28 | Catalyst |
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| Country | Link |
|---|---|
| JP (1) | JP2003062465A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8668877B2 (en) | 2010-11-24 | 2014-03-11 | Basf Corporation | Diesel oxidation catalyst articles and methods of making and using |
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|---|---|---|---|---|
| JPS5756041A (en) * | 1980-09-19 | 1982-04-03 | Mitsui Mining & Smelting Co Ltd | Palladium catalyst |
| JPS5881441A (en) * | 1981-11-11 | 1983-05-16 | Nippon Shokubai Kagaku Kogyo Co Ltd | Catalyst for purifying exhaust gas and preparation thereof |
| JPS5962344A (en) * | 1982-09-30 | 1984-04-09 | Toshiba Corp | Combustion catalyst for gas turbine |
| JPH08206506A (en) * | 1994-11-15 | 1996-08-13 | Inst Fr Petrole | Combusting catalyst and combusting method using the catalyst |
| JPH09500198A (en) * | 1993-03-04 | 1997-01-07 | エンゲルハード・コーポレーシヨン | Improved substrate morphology for catalytic combustion systems |
| JPH11104462A (en) * | 1997-09-30 | 1999-04-20 | Ngk Insulators Ltd | Catalyst-adsorber for purification of exhaust gas and purification of exhaust gas |
-
2001
- 2001-08-28 JP JP2001258162A patent/JP2003062465A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5756041A (en) * | 1980-09-19 | 1982-04-03 | Mitsui Mining & Smelting Co Ltd | Palladium catalyst |
| JPS5881441A (en) * | 1981-11-11 | 1983-05-16 | Nippon Shokubai Kagaku Kogyo Co Ltd | Catalyst for purifying exhaust gas and preparation thereof |
| JPS5962344A (en) * | 1982-09-30 | 1984-04-09 | Toshiba Corp | Combustion catalyst for gas turbine |
| JPH09500198A (en) * | 1993-03-04 | 1997-01-07 | エンゲルハード・コーポレーシヨン | Improved substrate morphology for catalytic combustion systems |
| JPH08206506A (en) * | 1994-11-15 | 1996-08-13 | Inst Fr Petrole | Combusting catalyst and combusting method using the catalyst |
| JPH11104462A (en) * | 1997-09-30 | 1999-04-20 | Ngk Insulators Ltd | Catalyst-adsorber for purification of exhaust gas and purification of exhaust gas |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8668877B2 (en) | 2010-11-24 | 2014-03-11 | Basf Corporation | Diesel oxidation catalyst articles and methods of making and using |
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