JPS61234932A - Catalyst for purifying exhaust gas of engine - Google Patents
Catalyst for purifying exhaust gas of engineInfo
- Publication number
- JPS61234932A JPS61234932A JP60074861A JP7486185A JPS61234932A JP S61234932 A JPS61234932 A JP S61234932A JP 60074861 A JP60074861 A JP 60074861A JP 7486185 A JP7486185 A JP 7486185A JP S61234932 A JPS61234932 A JP S61234932A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- alumina
- exhaust gas
- carrier
- purification performance
- 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.)
- Granted
Links
- 239000003054 catalyst Substances 0.000 title claims abstract description 112
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 56
- 238000000746 purification Methods 0.000 abstract description 27
- 229910052697 platinum Inorganic materials 0.000 abstract description 9
- 230000003197 catalytic effect Effects 0.000 abstract description 7
- 229910052703 rhodium Inorganic materials 0.000 abstract description 6
- 229910052763 palladium Inorganic materials 0.000 abstract description 4
- 229910052594 sapphire Inorganic materials 0.000 abstract 2
- 229910003158 γ-Al2O3 Inorganic materials 0.000 abstract 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 31
- 230000000694 effects Effects 0.000 description 14
- 239000010948 rhodium Substances 0.000 description 14
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 12
- 230000006866 deterioration Effects 0.000 description 11
- 239000002245 particle Substances 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 230000007704 transition Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000005245 sintering Methods 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 231100000572 poisoning Toxicity 0.000 description 4
- 230000000607 poisoning effect Effects 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910003609 H2PtCl4 Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 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 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- CLSUSRZJUQMOHH-UHFFFAOYSA-L platinum dichloride Chemical compound Cl[Pt]Cl CLSUSRZJUQMOHH-UHFFFAOYSA-L 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 230000007096 poisonous effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002940 repellent Effects 0.000 description 1
- 239000005871 repellent Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- SONJTKJMTWTJCT-UHFFFAOYSA-K rhodium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Rh+3] SONJTKJMTWTJCT-UHFFFAOYSA-K 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、エンジンの排気系に設けた排気ガス浄化用触
媒に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust gas purifying catalyst provided in an engine exhaust system.
（従来技術）
従来より、エンジンの排気ガスを浄化する触媒として、
例えば特開昭５８−１４６４４１号に見られるように、
Ｐｔ等の触媒成分を含有するウォッシュコート層にはγ
−アルミナが使用されている。このγ−アルミナはα−
アルミナに比べて、表面が粗くて気孔率が大きく、低温
下での活性性能が高いものである。(Prior art) Conventionally, catalysts have been used to purify engine exhaust gas.
For example, as seen in JP-A-58-146441,
The wash coat layer containing catalyst components such as Pt contains γ.
- Alumina is used. This γ-alumina is α-
Compared to alumina, it has a rougher surface, higher porosity, and higher activity at low temperatures.
しかるに、上記γ−アルミナは温度が高くなるとα−ア
ルミナに相転移し、表面が平滑になって気孔率が低下す
ることにより、含有されている触媒成分と排気ガスとの
接触面積が低減し、浄化性能が低下する熱劣化を生起す
るものである。特に、触媒成分としてＰｔが担持されて
いると、該Ｐｔが上記γ−アルミナからα−アルミナへ
の相転移を促進し、比較的低い温度からでも結晶化が進
行して上記相転移が生じやすく、浄化性能の熱劣化が大
きくなるものである。また、上記Ｐｔは高温状態で粒子
が結合するシンタリング現象により粒子が大きくなって
、さらに浄化性能が低下することになる。上記γ−アル
ミナから熱により相転移したα−アルミナに対し、最初
からα−アルミナにＰｔ等を担持した触媒は、排気ガス
浄化に寄与する触媒成分が多く、浄化性能に優れるもの
である。However, when the temperature increases, the γ-alumina undergoes a phase transition to α-alumina, and the surface becomes smooth and the porosity decreases, reducing the contact area between the contained catalyst components and the exhaust gas. This causes thermal deterioration that reduces purification performance. In particular, when Pt is supported as a catalyst component, the Pt promotes the phase transition from γ-alumina to α-alumina, and crystallization progresses even at relatively low temperatures, making it easy for the phase transition to occur. , thermal deterioration of purification performance increases. Furthermore, the particles of Pt become larger due to a sintering phenomenon in which particles are bonded together under high temperature conditions, further deteriorating the purification performance. In contrast to α-alumina, which has been phase-transformed from γ-alumina by heat, a catalyst in which Pt or the like is supported from the beginning on α-alumina has a large amount of catalytic components that contribute to exhaust gas purification, and has excellent purification performance.
（発明の目的）
本発明は上記事情に鑑み、α−アルミナとγ−アルミナ
との特性を利用して熱劣化を抑制し、良好な浄化性能を
維持するようにしたエンジンの排気ガス浄化用触媒を提
供することを目的とするものである。(Object of the Invention) In view of the above circumstances, the present invention provides a catalyst for purifying engine exhaust gas, which utilizes the characteristics of α-alumina and γ-alumina to suppress thermal deterioration and maintain good purification performance. The purpose is to provide the following.
（発明の構成）
本発明の触媒は、排気系上流側の第１触媒の触媒担体に
、少なくともＰｔを含有するα−アルミナ層を設ける一
方、下流側の第２触媒の触媒担体上にＰｔ以外のＰｄ等
の触媒成分を含有するγ−アルミナ層を設けたことを特
徴とするものである。(Structure of the Invention) In the catalyst of the present invention, an α-alumina layer containing at least Pt is provided on the catalyst carrier of the first catalyst on the upstream side of the exhaust system, while a layer other than Pt is provided on the catalyst carrier of the second catalyst on the downstream side. It is characterized by providing a γ-alumina layer containing a catalyst component such as Pd.
（発明の効果）
本発明によれば、触媒上流側は温度条件が厳しく耐熱性
が要求されるため、触媒を上流側の第１触媒と下流側の
第２触媒とに分け、上５ＩｉＨＩｌの触媒にはα−アル
ミナ層を形成することにより熱的に安定した活性を維持
することができるとともに、下流側は比較的温度が低下
する傾向にあるため、この下流側の第２触媒には活性の
優れたγ−アルミナ層を形成するようにしたことにより
、良好な浄化性能および耐久性が確保できるものである
。(Effects of the Invention) According to the present invention, since the temperature conditions on the upstream side of the catalyst are severe and heat resistance is required, the catalyst is divided into a first catalyst on the upstream side and a second catalyst on the downstream side, and It is possible to maintain thermally stable activity by forming an α-alumina layer on the catalyst, and since the temperature tends to be relatively low on the downstream side, the second catalyst on the downstream side has a high level of activity. By forming an excellent γ-alumina layer, good purification performance and durability can be ensured.
すなわち、上流側の第１触媒にＰｔが存在しても、この
部分はα−アルミナであるため、熱およびＰｔによる影
響を受けることなく相転移が生起せずに熱安定性に優れ
ており、このα−アルミナの気孔率はγ−アルミナに比
べて低いが、その気孔部分に有効に触媒成分が担持され
ており、触媒全体として熱劣化が少なく安定した排気浄
化性能が得られるものである。That is, even if Pt is present in the first catalyst on the upstream side, since this part is α-alumina, it is not affected by heat and Pt, and has excellent thermal stability without causing phase transition. Although the porosity of α-alumina is lower than that of γ-alumina, the catalyst component is effectively supported in its pores, and the catalyst as a whole exhibits less thermal deterioration and stable exhaust purification performance.
（実施例） 以下、図面により本発明の実施例を詳細に説明する。(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.
第１図は排気ガス浄化用触媒の構成図、第２図は触媒の
要部拡大断面図であり、排気系１の途中に形成された触
媒容器２内に、上流側の第１触媒３と下流側の第２触媒
４とによるモノリス型触媒５が介装されている。FIG. 1 is a configuration diagram of an exhaust gas purification catalyst, and FIG. 2 is an enlarged cross-sectional view of the main parts of the catalyst. A monolithic catalyst 5 is interposed with a second catalyst 4 on the downstream side.
上記上流側の第１触媒３は、触媒担体６（モノリス壁体
）の表面部分にＰｔ（白金）、Ｒｈ（ロジウム）を担持
したα−アルミナ層７（ウォッシュコート層）を設けて
なり、下流側の第２触ｔＪｓ４は、触媒担体６の表面部
分にＰｄ（パラジウム）を担持したγ−アルミナ層８（
ウォッシュコート層）を設けてなるものである。なお、
ＰｔおよびＰｄは排気ガス中のＣ０１ＨＣの浄化性能に
優れ、Ｒｈ Ｇ、ｔ Ｎ ＯＸの浄化性能に優れ、この
３成分によって一度に排気ガスの有害成分の浄化が行え
る。The first catalyst 3 on the upstream side is formed by providing an α-alumina layer 7 (wash coat layer) supporting Pt (platinum) and Rh (rhodium) on the surface portion of a catalyst carrier 6 (monolith wall body). The second contact tJs4 on the side is a γ-alumina layer 8 (with Pd (palladium) supported on the surface portion of the catalyst carrier 6).
wash coat layer). In addition,
Pt and Pd have excellent purification performance of CO1HC in exhaust gas, and excellent purification performance of Rh G and t NO OX, and these three components can purify harmful components of exhaust gas at once.
上記触媒５は、同一担体６に第１触媒３と第２触媒４を
形成するもの、もしくは別々の担体にそれぞれ形成した
第１触媒３と第２触ｔｓ４とを組付けるものなどがある
。The catalyst 5 may be one in which the first catalyst 3 and the second catalyst 4 are formed on the same carrier 6, or one in which the first catalyst 3 and the second catalyst 4 are respectively formed on separate carriers.
同一担体６に第１触媒３と第２触媒４とを形成する製造
法について説明する。まず、触媒担体６としてコージラ
イト質モノリス担体（４００セル）を用意する。また、
蒸溜水１ｏｏｃｃに硝酸０．４ＣＣを加えた溶液に、担
体重量に対し２５Ｗ【％のウォッシュコート層になるよ
うにα−アルミナ粉末とバインダーを添加し、充分撹拌
してスラリー液を調整する。A manufacturing method for forming the first catalyst 3 and the second catalyst 4 on the same carrier 6 will be explained. First, a cordierite monolith carrier (400 cells) is prepared as the catalyst carrier 6. Also,
Add α-alumina powder and a binder to a solution of 0.4 cc of nitric acid in 1 oocc of distilled water to form a wash coat layer of 25 W% based on the carrier weight, and stir thoroughly to prepare a slurry liquid.
このスラリー液に上記触媒担体６を所定位置まで浸漬し
た後、セル内の不要なスラリーはエアーブローにより除
去し、α−アルミナによるウォッシュコート層を形成す
る。上記担体６を塩化白金Ｈ（Ｈ２ＰｔＣｌ４）と塩化
ロジウム（ＲｉｌＣＩ）を含有する水溶液による触媒液
に浸漬し、エアーブローを行う。上記スラリー液および
触媒液が第１触媒３となる所定位置より上の第２触媒４
部分の担体６に含浸しないように、第２触媒４となる部
分には予め撥水剤（オイル）を含浸させてマスキングを
行うものである。After the catalyst carrier 6 is immersed in this slurry liquid to a predetermined position, unnecessary slurry inside the cell is removed by air blowing, and a wash coat layer of α-alumina is formed. The carrier 6 is immersed in a catalyst solution made of an aqueous solution containing platinum chloride H (H2PtCl4) and rhodium chloride (RilCI), and then air blown. A second catalyst 4 above a predetermined position where the slurry liquid and catalyst liquid become the first catalyst 3
The portion that will become the second catalyst 4 is previously impregnated with a water repellent (oil) and masked so as not to impregnate the carrier 6 in that portion.
その後、２２０℃で８分間乾燥して、さらに、３３０℃
で１時間焼成しオイルを焼失することによって、担体６
にＰｔ、Ｒｈを含むα−アルミナ層７を形成して第１触
媒３を得る。Then, dry at 220°C for 8 minutes, and then dry at 330°C.
By baking for 1 hour to burn off the oil, the carrier 6
A first catalyst 3 is obtained by forming an α-alumina layer 7 containing Pt and Rh.
次に、上記と同様な方法によりγ−アルミナを含有した
スラリー液に、第２触媒４を形成する部分の担体６を浸
漬した後、エアーブローを行って、γ−アルミナによる
ウォッシュコート層を形成する。上記担体６を塩化パラ
ジウム（ＰｄＣ１）を含有する水溶液による触媒液に浸
漬し、エアーブローを行う。この場合も、前記と同様に
第１触媒３の部分に対して、予めオイルを含浸させてマ
スキングを行うものである。Next, the part of the carrier 6 that will form the second catalyst 4 is immersed in a slurry liquid containing γ-alumina in the same manner as above, and then air blowing is performed to form a wash coat layer of γ-alumina. do. The carrier 6 is immersed in a catalyst solution made of an aqueous solution containing palladium chloride (PdC1), and then air blown. In this case as well, masking is performed by impregnating the first catalyst 3 with oil in advance in the same manner as described above.
その後、３００℃で８分間乾燥して、さらに、４００℃
で１３分、５００℃で１２分、６００℃で３３分と段階
的に焼成しオイルを焼失することによって、担体６にＰ
ｄを含むγ−アルミナ層８を形成して第２触媒４を得る
。これにより、例えば触媒の１／２にＰｔ、Ｒｈを含有
したα−アルミナ層７が、他の１／２にＰｄを含有した
γ−アルミナ層８が形成された第１触媒３と第２触媒４
とを有する触媒５を得るものである。Then, dry at 300°C for 8 minutes, and then dry at 400°C.
P is added to the carrier 6 by burning out the oil by stepwise baking: 13 minutes at 500°C, 12 minutes at 600°C, and 33 minutes at 600°C.
A second catalyst 4 is obtained by forming a γ-alumina layer 8 containing d. As a result, for example, the first catalyst 3 and the second catalyst have an α-alumina layer 7 containing Pt and Rh formed in one half of the catalyst, and a γ-alumina layer 8 containing Pd formed in the other half of the catalyst. 4
A catalyst 5 having the following is obtained.
なお、上記オイルを使用しないで直接担体６に触媒液を
含浸させると、触媒担体６の周囲の部分が毛細管現象に
より中心部より高い位置まで含浸し、この周囲の部分は
境界付近で第１触媒３と第２触媒４との触媒成分が混合
する一方、中心部分には触媒成分が含浸されていない状
態に形成され、浄化性能が充分に得られない。Note that if the catalyst liquid is directly impregnated into the carrier 6 without using the above oil, the peripheral part of the catalyst carrier 6 will be impregnated to a higher position than the center due to capillary action, and this peripheral part will be impregnated with the first catalyst near the boundary. While the catalyst components of the second catalyst 3 and the second catalyst 4 are mixed, the central portion is not impregnated with the catalyst component, and sufficient purification performance cannot be obtained.
上記触媒の効果を確認した試験結果を示す。第４図は上
記と同様の方法によって形成した触媒の排気ガス温度に
対する排気ガス浄化性能（Ｈｅ浄化率）を、使用ｒＭ始
時の熱劣化前と、１０００℃で６時間熱劣化させた後と
でそれぞれ求めた結果を比較例とともに示す。なお、本
発明触媒の触媒液における触媒成分の濃度は、第１触媒
３においてはＰｔ／Ｒｈ−４／１−１．４Ｑ／９．で、
第２触＊４ｋｊ５いＴはＰｄ−１，１／免であり、第１
触媒３と第２触媒４との比率は１：１である。The test results confirming the effectiveness of the above catalyst are shown below. Figure 4 shows the exhaust gas purification performance (He purification rate) with respect to the exhaust gas temperature of the catalyst formed by the same method as above before thermal deterioration at the beginning of use and after thermal deterioration at 1000°C for 6 hours. The results obtained for each are shown together with comparative examples. Note that the concentration of the catalyst components in the catalyst liquid of the catalyst of the present invention is Pt/Rh-4/1-1.4Q/9. in,
The second touch*4kj5iT is Pd-1,1/min, and the first
The ratio of catalyst 3 to second catalyst 4 is 1:1.
また、比較例は、ウォッシュコート全体をγ−アルミナ
層で形成したものである。Moreover, in the comparative example, the entire washcoat was formed of a γ-alumina layer.
第４図から分るように、本発明触媒は比較例のものに対
して、熱劣化前においてはγ−アルミナの方が活性性能
が高いことから浄化性能は若干劣るが、熱劣化後は比較
例のものが相転移によって活性低下が大きくなって浄化
性能は逆転し、本発明によるものは低い温度から活性化
し、安定した浄化性能が得られている。As can be seen from Figure 4, the purification performance of the catalyst of the present invention is slightly inferior to that of the comparative example because γ-alumina has higher activity performance before thermal deterioration, but after thermal deterioration, the purification performance is slightly inferior to that of the comparative example. In the case of the example, the activity decreases greatly due to phase transition and the purification performance is reversed, whereas the case of the present invention is activated from a low temperature and stable purification performance is obtained.
また、熱劣化に伴うＰｔの粒子径の変化は第５図に示す
ように、比較例におけるγ−アルミナ層のＰｔは、シン
タリング現象によってその平均粒子径が劣化処理後（１
０００℃Ｘ６ｈｒ）においては大幅に増大しているのに
対して、本発明のα−アルミナ層のＰｔはその粒子径の
増加率は低いものである。Furthermore, as shown in Figure 5, the change in the particle size of Pt due to thermal deterioration shows that the average particle size of Pt in the γ-alumina layer in the comparative example changes due to the sintering phenomenon after the deterioration treatment (1
000° C. x 6 hr), whereas the particle size of Pt in the α-alumina layer of the present invention increases at a low rate.
さらに、γ−アルミナにおけるＰｔの含有によるアルミ
ナの結晶化状態をＸ線回折で測定した結果は、第６図に
示すように、Ｐｔの介在によってα−アルミナへの相転
移が低い温度から進行しているのが分る。α−アルミナ
は熱による細孔分布など物理的特性の変化は少なく、ま
た、触媒成分の分散性への影響も少なく、前記のように
熱的に安定している。Furthermore, the results of X-ray diffraction measurements of the crystallization state of alumina due to the inclusion of Pt in γ-alumina show that the phase transition to α-alumina progresses from a low temperature due to the presence of Pt, as shown in Figure 6. I can see that it is. α-Alumina has little change in physical properties such as pore distribution due to heat, has little effect on the dispersibility of catalyst components, and is thermally stable as described above.
上記実施例によれば、Ｐｔ−Ｒｈ−Ｐｄ系触媒において
、ＰｄがＰｔあるいはＲｈと共存すると、これらの相互
作用による合金化により、触媒の活性性能が低下する問
題があるが、触媒をＰｔおよびＲｈを含有する上流側の
第１触媒３と、Ｐｄを含有する下流側の第２触媒４とに
分けたことにより、両者間の相互作用による合金化を防
止でき、各成分の活性性能を良好に維持することができ
る。According to the above example, in a Pt-Rh-Pd-based catalyst, when Pd coexists with Pt or Rh, there is a problem that the activity performance of the catalyst decreases due to alloying due to interaction between them. By dividing the catalyst into the first catalyst 3 on the upstream side containing Rh and the second catalyst 4 on the downstream side containing Pd, it is possible to prevent alloying due to interaction between the two and improve the activity performance of each component. can be maintained.
また、上記各触媒成分の耐被毒性がＰｔ＞Ｒｈ＞Ｐｄの
順である点を考慮し、耐被毒性に優れたＰｔおよびＲｈ
を排気ガス中のＰ、Ｐｂ、Ｓ等の被毒物質が付着しやす
い上流側部分の第１触媒３に設けたことにより、全体と
しての耐被毒性が向上できる。しかも、上流側のＰｔ−
Ｒｈ触媒が被毒等の影響を受けても、下流側のＰｄ触媒
には排気ガスが接触して有効に浄化作用が機能するもの
である。In addition, considering the fact that the poisoning resistance of each of the catalyst components is in the order of Pt>Rh>Pd, Pt and Rh, which have excellent poisoning resistance,
By providing the first catalyst 3 in the upstream portion where poisonous substances such as P, Pb, and S in the exhaust gas tend to adhere, the overall poisoning resistance can be improved. Moreover, the upstream Pt-
Even if the Rh catalyst is affected by poisoning or the like, exhaust gas comes into contact with the Pd catalyst on the downstream side, and the purifying action is effective.
さらに、上記各触媒成分の耐熱性がＰｄ ＞Ｒｈ＞Ｐｔ
の順である点を考慮し、Ｐｔは高温状態で粒子が結合す
るシンタリング現象により粒子が大きくなって浄化性能
が低下することで耐熱性が低いが、このＰｔを熱的安定
性に優れたα−アルミナ層７に担持するとともに、Ｐｔ
より耐熱性に優れたＲｈが介在しているので、温度上昇
によってＰｔ粒子が結合して大きな粒子となるのをＲｈ
が阻止してシンタリング現象の発生を防止し、安定な浄
化性能が得られる。Furthermore, the heat resistance of each of the above catalyst components is Pd>Rh>Pt
Considering the fact that Pt has low heat resistance due to the sintering phenomenon in which particles bond together at high temperatures, the particles become larger and the purification performance decreases. In addition to being supported on the α-alumina layer 7, Pt
Since Rh, which has better heat resistance, is present, Rh prevents Pt particles from bonding to become larger particles due to temperature rise.
This prevents the occurrence of sintering phenomenon and provides stable purification performance.
第３図は変形例を示し、この例の触媒５′は、上記実施
例における第２触媒４のγ−アルミナ層８を、第１触媒
３における触媒担体６とα−アルミナ層７との間にも形
成したものであり、その他は前例と同様である。FIG. 3 shows a modified example, and the catalyst 5' of this example has the γ-alumina layer 8 of the second catalyst 4 in the above embodiment between the catalyst carrier 6 and the α-alumina layer 7 of the first catalyst 3. The other features are the same as in the previous example.
上記第３図の例において、γ−アルミナ層８を担体６の
全体に形成するのは、触媒５の温度が高くなる部分は、
上流側でしかも表面側であって、この部分にα−アルミ
ナ層７を形成し、下層側は担体６と接しているので熱が
放散されて熱的影響が少ないことから、上記α−アルミ
ナ層７の形成による活性性能の低下を補うためにγ−ア
ルミナ層８を広く形成したものである。すなわち、α−
アルミナ１１７は前述のように、熱的安定性優れている
が活性性能が低いので、湿度の低い部分には活性性能に
優れたγ−アルミナ層８を形成することによって、活性
性能を向上するようにしたものである。In the example shown in FIG. 3 above, the reason why the γ-alumina layer 8 is formed on the entire carrier 6 is because the portion where the temperature of the catalyst 5 becomes high is
The α-alumina layer 7 is formed on the upstream side and on the surface side, and the lower layer side is in contact with the carrier 6, so heat is dissipated and there is little thermal influence. The γ-alumina layer 8 is formed to be wide in order to compensate for the decrease in activity performance caused by the formation of the γ-alumina layer 8. That is, α−
As mentioned above, alumina 117 has excellent thermal stability but low activity performance, so the activity performance can be improved by forming the γ-alumina layer 8, which has excellent activity performance, in areas with low humidity. This is what I did.
なお、上記実施例においては、第１触ｔｓ３のα−アル
ミナ層７にはＰｔに加えてＲｈを含有するようにしてＮ
Ｏｘの浄化性能の向上およびシンタリング現象の抑制を
行うようにしているが、Ｐｔだけを含有させるようにし
てもよい。また、第２触媒４のγ−アルミナ層８は、長
時間の使用後には相転移によって活性性能が低下するが
、それを補うために触媒助剤としてＮｉ、Ｆｅ、Ｃｅ等
を添加するようにしてもよく、α−アルミナ層７にも同
様に添加してもよい。In the above embodiment, the α-alumina layer 7 of the first contact ts3 contains Rh in addition to Pt, so that N
Although the purification performance of Ox is improved and the sintering phenomenon is suppressed, only Pt may be contained. In addition, the activity of the γ-alumina layer 8 of the second catalyst 4 decreases due to phase transition after long-term use, but to compensate for this, Ni, Fe, Ce, etc. are added as catalyst aids. It may also be added to the α-alumina layer 7 in the same way.
さらに、上記実施例においては、触媒担体６にウォッシ
ュコート層を形成してから触媒液に浸漬するようにして
いるが、ウォッシュコート層を形成するスラリー液に予
め触媒成分を添加混合し、これに触媒担体を浸漬して形
成するようにしてもよい。Furthermore, in the above embodiment, the wash coat layer is formed on the catalyst carrier 6 and then immersed in the catalyst liquid. It may also be formed by dipping the catalyst carrier.
第１図は本発明の一実施例における排気ガス浄化用触媒
の構成図、
第２図は触媒の要部を拡大して示す断面図、第３図は変
形例における触媒の要部を拡大して示す断面図、
第４図は熱劣化による排気ガス浄化性能の変化を比較例
とともに示す排気ガス温度とＨＣ浄化率のグラフ、
第５図は本発明のα−アルミナと比較例のγ−アルミナ
における熱劣化によるＰｔの粒子径の変化を示す説明図
、
第６図はγ−アルミナのＰｔの介在による結晶化状態を
示すＸ線回折測定図である。
１・・・・・・排気系 ２・・・・・・触媒
容器３・・・・・・第１触媒 ４・・・・・・
第２触媒５・・・・・・モノリス型触媒 ６・・・・
・・触媒担体７・・・・・・α−アルミナ層 ８・・
・・・・γ−アルミナ層Ｏく・禰
ｏく ・鴫
エケ３薙 どFig. 1 is a configuration diagram of an exhaust gas purifying catalyst according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view showing the main parts of the catalyst, and Fig. 3 is an enlarged view of the main parts of the catalyst in a modified example. Figure 4 is a graph of exhaust gas temperature and HC purification rate showing changes in exhaust gas purification performance due to thermal deterioration along with comparative examples. Figure 5 is a graph of α-alumina of the present invention and γ-alumina of comparative example. FIG. 6 is an X-ray diffraction measurement diagram showing the crystallization state of γ-alumina due to the presence of Pt. 1... Exhaust system 2... Catalyst container 3... First catalyst 4...
Second catalyst 5... Monolith type catalyst 6...
...Catalyst carrier 7...α-alumina layer 8...
...γ-alumina layer
Claims (1)
おいて、上流側の第１触媒の触媒担体に少なくともＰｔ
を含有するα−アルミナ層を設け、下流側の第２触媒の
触媒担体上にＰｔ以外のＰｄ等の触媒成分を含有するγ
−アルミナ層を設けたことを特徴とするエンジンの排気
ガス浄化用触媒。(1) In the exhaust gas purifying catalyst provided in the exhaust system of the engine, at least Pt is added to the catalyst carrier of the first catalyst on the upstream side.
A γ-alumina layer containing a catalyst component other than Pt such as Pd is provided on the catalyst carrier of the second catalyst on the downstream side.
-A catalyst for purifying engine exhaust gas, characterized by having an alumina layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60074861A JPS61234932A (en) | 1985-04-09 | 1985-04-09 | Catalyst for purifying exhaust gas of engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60074861A JPS61234932A (en) | 1985-04-09 | 1985-04-09 | Catalyst for purifying exhaust gas of engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61234932A true JPS61234932A (en) | 1986-10-20 |
| JPH0554380B2 JPH0554380B2 (en) | 1993-08-12 |
Family
ID=13559526
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60074861A Granted JPS61234932A (en) | 1985-04-09 | 1985-04-09 | Catalyst for purifying exhaust gas of engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61234932A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001205051A (en) * | 2000-01-27 | 2001-07-31 | Cataler Corp | Catalyst for purifying exhaust gas |
| JP2008520895A (en) * | 2004-11-23 | 2008-06-19 | ジョンソン、マッセイ、パブリック、リミテッド、カンパニー | Exhaust mechanism with exothermic catalyst |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4827125A (en) * | 1971-08-11 | 1973-04-10 | ||
| JPS5541894A (en) * | 1978-09-18 | 1980-03-24 | Ford Motor Co | Alpha aluminaametal rhodium catalyst |
| JPS55164715A (en) * | 1979-06-09 | 1980-12-22 | Fuji Heavy Ind Ltd | Catalytic converter used for purifying exhaust gas |
| JPS5787837A (en) * | 1980-11-20 | 1982-06-01 | Toyota Motor Corp | Production of catalyst for purification of waste gas |
| JPS58146441A (en) * | 1982-02-24 | 1983-09-01 | Toyota Motor Corp | Catalyst for purification of exhaust gas |
-
1985
- 1985-04-09 JP JP60074861A patent/JPS61234932A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4827125A (en) * | 1971-08-11 | 1973-04-10 | ||
| JPS5541894A (en) * | 1978-09-18 | 1980-03-24 | Ford Motor Co | Alpha aluminaametal rhodium catalyst |
| JPS55164715A (en) * | 1979-06-09 | 1980-12-22 | Fuji Heavy Ind Ltd | Catalytic converter used for purifying exhaust gas |
| JPS5787837A (en) * | 1980-11-20 | 1982-06-01 | Toyota Motor Corp | Production of catalyst for purification of waste gas |
| JPS58146441A (en) * | 1982-02-24 | 1983-09-01 | Toyota Motor Corp | Catalyst for purification of exhaust gas |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001205051A (en) * | 2000-01-27 | 2001-07-31 | Cataler Corp | Catalyst for purifying exhaust gas |
| JP2008520895A (en) * | 2004-11-23 | 2008-06-19 | ジョンソン、マッセイ、パブリック、リミテッド、カンパニー | Exhaust mechanism with exothermic catalyst |
| JP2012125765A (en) * | 2004-11-23 | 2012-07-05 | Johnson Matthey Plc | Exhaust system comprising exotherm-generating catalyst |
| US8220251B2 (en) | 2004-11-23 | 2012-07-17 | Johnson Matthey Public Limited Company | Exhaust system comprising exotherm-generating catalyst |
| US8925304B2 (en) | 2004-11-23 | 2015-01-06 | Johnson Matthey Public Limited Company | Exhaust system comprising exotherm-generating catalyst |
| US9528408B2 (en) | 2004-11-23 | 2016-12-27 | Johnson Matthey Public Limited Company | Exhaust system comprising exotherm-generating catalyst |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0554380B2 (en) | 1993-08-12 |
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