JPH0811197B2 - Exhaust gas purification catalyst manufacturing method - Google Patents
Exhaust gas purification catalyst manufacturing methodInfo
- Publication number
- JPH0811197B2 JPH0811197B2 JP61310580A JP31058086A JPH0811197B2 JP H0811197 B2 JPH0811197 B2 JP H0811197B2 JP 61310580 A JP61310580 A JP 61310580A JP 31058086 A JP31058086 A JP 31058086A JP H0811197 B2 JPH0811197 B2 JP H0811197B2
- Authority
- JP
- Japan
- Prior art keywords
- alumina
- catalyst
- ultrafine
- powder
- exhaust gas
- 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.)
- Expired - Lifetime
Links
- 239000003054 catalyst Substances 0.000 title claims description 87
- 238000004519 manufacturing process Methods 0.000 title claims description 29
- 238000000746 purification Methods 0.000 title description 19
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 93
- 239000000843 powder Substances 0.000 claims description 37
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 24
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 24
- 239000002245 particle Substances 0.000 claims description 20
- 239000002002 slurry Substances 0.000 claims description 20
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 230000000052 comparative effect Effects 0.000 description 28
- 239000010410 layer Substances 0.000 description 16
- 238000010304 firing Methods 0.000 description 15
- 230000003197 catalytic effect Effects 0.000 description 13
- 230000000694 effects Effects 0.000 description 12
- 238000011056 performance test Methods 0.000 description 11
- 238000005259 measurement Methods 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 8
- 238000001354 calcination Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 229910001593 boehmite Inorganic materials 0.000 description 6
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 6
- 229910052703 rhodium Inorganic materials 0.000 description 5
- 239000010948 rhodium Substances 0.000 description 5
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 5
- 239000011247 coating layer Substances 0.000 description 4
- 229910052697 platinum Inorganic materials 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- SONJTKJMTWTJCT-UHFFFAOYSA-K rhodium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Rh+3] SONJTKJMTWTJCT-UHFFFAOYSA-K 0.000 description 3
- 229910052878 cordierite Inorganic materials 0.000 description 2
- 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 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002345 surface coating layer Substances 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、排気ガス浄化用触媒の製造法に関し、例え
ば自動車の排気ガス浄化用としてエンジンから排出され
る有害物質（HC,CO,NOx）を除去するために、また一般
の工業用の排気ガス浄化用としても利用されるものの改
良に関する。Description: TECHNICAL FIELD The present invention relates to a method for producing an exhaust gas purifying catalyst, for example, harmful substances (HC, CO, NOx) emitted from an engine for purifying exhaust gas of an automobile. The present invention relates to improvement of those used for removing exhaust gas and for purifying exhaust gas for general industrial use.
（従来の技術） 一般に、自動車の排気ガス浄化用触媒は、コーディラ
イト製（2MgO・2Al2O3・5SiO2）のモノリス型触媒担体
の表面に、アルミナおよび白金やロジウム等の触媒金属
からなるコート層が設けられた構成になっている。触媒
金属は、コート層においてアルミナにより担持されてお
り、アルミナは触媒金属の担体として重要な役割を有す
る。(Prior Art) Generally, an automobile exhaust gas purifying catalyst is composed of a catalyst metal such as alumina and platinum or rhodium on the surface of a monolith type catalyst carrier made of cordierite (2MgO · 2Al 2 O 3 · 5SiO 2 ). It has a structure in which a coat layer is provided. The catalytic metal is supported by alumina in the coat layer, and alumina plays an important role as a carrier for the catalytic metal.
そして、このような排気ガス浄化用触媒の製造法は、
通常、次の手順によって行われている。すなわち、先
ず、γ−アルミナやベーマイトを水および濃硝酸と混合
撹拌してアルミナスラリーを調整し、このアルミナスラ
リーに触媒担体を浸漬し、焼成をする。次いで、このア
ルミナコートを施した触媒担体を、触媒金属の水溶液
（塩化白金酸・塩化ロジウム水溶液）に浸漬し、焼成を
するのである。And, the manufacturing method of such an exhaust gas purifying catalyst is
Usually, the procedure is as follows. That is, first, γ-alumina and boehmite are mixed and stirred with water and concentrated nitric acid to prepare an alumina slurry, and a catalyst carrier is immersed in the alumina slurry and baked. Then, the catalyst carrier coated with this alumina is immersed in an aqueous solution of a catalytic metal (an aqueous solution of chloroplatinic acid / rhodium chloride) and baked.
また、特開昭61-38632号公報には、ガス中蒸発法で生
成したアルミナおよび触媒金属の超微粉を、繊維状担体
中に通過せしめて該担体の繊維表面に付着させることが
開示されている。このような触媒の製造法は、アルミナ
および触媒金属の超微粉において、その粒子径が均一か
つ微小で比表面積が非常に大きく、また表面活性が強い
などの特性を有することに着目し、これらの特性を利用
して触媒の浄化性能を高めるようにしたものである。Further, JP-A-61-38632 discloses that ultrafine powder of alumina and catalytic metal produced by a gas evaporation method is passed through a fibrous carrier and adhered to the fiber surface of the carrier. There is. Focusing on the fact that the method for producing such a catalyst has characteristics that the ultrafine powder of alumina and the catalyst metal has a uniform and fine particle diameter, an extremely large specific surface area, and a strong surface activity, and The characteristics are used to improve the purification performance of the catalyst.
（発明が解決しようとする問題点） ところで、触媒担体表面コート層におけるアルミナ
は、触媒金属を担持するという単なる支持物ではなく、
触媒金属の活性、選択性および永続性に大きな影響を与
えるものといえる。つまり、アルミナは、触媒金属のシ
リンダリンク（熱により粒子が大きくなり、触媒作用が
生じなくなるという現象）を防止し、安定な活性を維持
するとともに、触媒金属との界面を通して触媒金属の電
子状態に影響を与え、その触媒作用を微妙に制御してい
ると考えられる。この点については、従来、余り配慮が
なされていない。(Problems to be Solved by the Invention) By the way, the alumina in the catalyst carrier surface coating layer is not a mere support for supporting the catalyst metal,
It can be said to have a great influence on the activity, selectivity and permanence of the catalytic metal. In other words, alumina prevents the catalytic metal cylinder link (a phenomenon in which particles become large due to heat and the catalytic action does not occur), maintains stable activity, and becomes an electronic state of the catalytic metal through the interface with the catalytic metal. It is thought that it exerts an influence and delicately controls its catalytic action. Conventionally, this point has not been considered so much.
一方、上記記載の公報（特開昭61-38632号）のものの
場合、アルミナが超微粉のものであるため、その粒子と
触媒金属の粒子との界面を通しての相互作用が強くな
り、触媒金属の活性および選択性が改善されて、触媒の
浄化性能を高めることができるのであるが、耐久性の欠
けるという問題がある。すなわち、アルミナの超微粉自
体は、その粒子径が均一かつ微小であって、結晶状態も
熱に対して安定なものであるが、アルミナの超微粉同士
の結合力が小さいため、コート層におけるアルミナの全
てを超微粉とすると、このコート層の触媒担体に対する
密着性が低く、また触媒金属の担持力も弱くなるので、
熱影響により剥離が生じ易いからである。On the other hand, in the case of the above-mentioned publication (Japanese Patent Laid-Open No. 61-38632), since alumina is an ultrafine powder, the interaction between the particles and the particles of the catalytic metal becomes strong, and Although the activity and selectivity can be improved and the purification performance of the catalyst can be enhanced, there is a problem of lack of durability. That is, the ultrafine powder of alumina itself has a uniform and fine particle size and the crystalline state is stable against heat, but since the binding force between the ultrafine powders of alumina is small, the alumina in the coat layer is small. When all of the above are ultrafine powder, the adhesion of the coating layer to the catalyst carrier is low, and the supporting ability of the catalyst metal is weak,
This is because peeling easily occurs due to the influence of heat.
本発明はかかる諸点に鑑みてなされたものであり、そ
の目的とするところは、排気ガス浄化用触媒の製造法に
おいて、触媒担体の表面に設けられるコート層のアルミ
ナのうち、所定の大きさのアルミナの超微粉が所定の割
合で占めるように改良して、触媒の浄化性能および耐久
性を高め得るようにするものである。The present invention has been made in view of the above points, and an object of the present invention is, in the method for producing an exhaust gas purifying catalyst, of the alumina of the coat layer provided on the surface of the catalyst carrier, having a predetermined size. It is intended to improve the purification performance and durability of the catalyst by improving it so that the ultrafine powder of alumina occupies a predetermined ratio.
（問題点を解決するための手段） 上記目的を達成するため、本発明の解決手段は、排気
ガス浄化用触媒の製造法として、先ず、従来の製造法の
場合と同様に調整したアルミナスラリーに、平均粒径が
5000Å以下のアルミニウムの超微粒をアルミナ全重量の
５〜50重量％を占める割合で添加混合する。次いで、こ
のアルミナスラリーに触媒担体を浸漬し、焼成をする。
しかる後、このアルミナコートを施した触媒担体を、触
媒金属の水溶液に浸漬し、焼成をする構成としたもので
ある。(Means for Solving the Problems) In order to achieve the above object, the solution of the present invention is as follows: First, as a method for producing an exhaust gas purifying catalyst, an alumina slurry prepared in the same manner as in the case of a conventional production method is used. , The average particle size is
Ultrafine aluminum particles of 5000 Å or less are added and mixed in a proportion of 5 to 50% by weight of the total weight of alumina. Next, the catalyst carrier is immersed in this alumina slurry and fired.
Then, the catalyst carrier coated with the alumina is immersed in an aqueous solution of a catalyst metal and fired.
（作用） 上記の構成により、本発明では、アルミニウムの超微
粉を添加混合したアルミナスラリーに触媒担体を浸漬し
て、該触媒担体の表面に、アルミナ全重量のうちアルミ
ナの超微粉が所定の割合を占めるアルミナコートを施し
たことによって、上記アルミナ超微粉における、比表面
積が大きく、かつ表面活性が強いなどの特性に基づい
て、その粒子と触媒金属の粒子との界面を通しての相互
作用が強くなるので、触媒金属の活性および選択性が改
善され、触媒の浄化性能が高められる。(Operation) According to the present invention, the catalyst carrier is soaked in the alumina slurry to which the ultrafine powder of aluminum is added and mixed, and the surface of the catalyst carrier is provided with a predetermined ratio of the ultrafine powder of alumina in the total weight of alumina. By virtue of the characteristics such as the alumina ultrafine powder having a large specific surface area and strong surface activity, the interaction between the particles and the catalyst metal particles through the interface is strengthened by applying the alumina coating Therefore, the activity and selectivity of the catalyst metal are improved, and the purification performance of the catalyst is enhanced.
しかも、上記アルミナコート層におけるアルミナの超
微粉は、そのコート層のアルミナ全重量の所定の割合
（５〜50重量％）を占めるにすぎず、他の通常の大きさ
（平均粒径が１μ以上）のアルミナによって、コート層
の触媒担体に対する密着性および触媒金属の担持力が十
分に確保され、熱影響による剥離を効果的に防止するこ
とができる。また、アルミナの超微粉における、熱に対
して結晶状態が安定で比表面積および細孔容積の低下が
少ないという特性に基づいて、焼成時間を短縮すること
ができるとともに、焼成温度を低くすることができる。Moreover, the ultrafine powder of alumina in the alumina coat layer occupies only a predetermined ratio (5 to 50% by weight) of the total weight of alumina in the coat layer, and has another normal size (average particle size of 1 μm or more). The alumina of 1) sufficiently secures the adhesion of the coat layer to the catalyst carrier and the carrying ability of the catalyst metal, and can effectively prevent the peeling due to the influence of heat. In addition, the firing time can be shortened and the firing temperature can be lowered based on the characteristics that the crystalline state of the ultrafine alumina powder is stable against heat and the specific surface area and the pore volume are less likely to decrease. it can.
（実施例） 以下、本発明の実施例について説明する。(Example) Hereinafter, the Example of this invention is described.
本発明の第１実施例に係る排気ガス浄化用触媒の製造
法は、先ず、平均粒径が500Åのアルミニウムの超微粉1
4.0gを、γ−アルミナ63g、ベーマイト63g、水200ccお
よび濃硝酸1.6ccと共にホモミキサーにより５時間混合
撹拌する。そして、このアルミナスラリーにコーディラ
イト製のハニカム型触媒担体を浸漬して引き上げた後、
余分のスラリーを高圧エアブローで除去し、130℃で１
時間乾燥し、さらに500℃で45分間焼成をする。この焼
成時には、触媒担体の表面に施したコート層におけるア
ルミニウムの超微粉は、酸化反応を生じてγ−アルミナ
（Al2O3）の超微粉に変化し、そのアルミナ超微粉の含
有量は、コート層のアルミナ全重量に対して約10wt％
（重量パーセント）である。In the method for producing an exhaust gas purifying catalyst according to the first embodiment of the present invention, first, ultrafine aluminum powder having an average particle size of 500Å is used.
4.0 g is mixed and stirred with 63 g of γ-alumina, 63 g of boehmite, 200 cc of water and 1.6 cc of concentrated nitric acid by a homomixer for 5 hours. Then, after immersing the honeycomb type catalyst carrier made of cordierite in this alumina slurry and pulling it up,
Excess slurry is removed by high pressure air blow, and 1
Dry for an hour and bake at 500 ° C for 45 minutes. At the time of this calcination, the ultrafine powder of aluminum in the coating layer applied to the surface of the catalyst carrier was changed into ultrafine powder of γ-alumina (Al 2 O 3 ) by an oxidation reaction, and the content of the alumina ultrafine powder was About 10 wt% of the total weight of alumina in the coating layer
(Weight percent).
次いで、上記アルミナコートを施した触媒担体を、所
定の濃度の塩化白金酸および塩化ロジウムの混合水溶液
に浸漬して引き上げた後、150℃で30分間乾燥し、さら
に500℃で45分間焼成をする。以上によって、触媒担体
の表面に、触媒金属としての白金およびロジウムを担持
したアルミナコート層が設けられてなる触媒が製造され
る。尚、この触媒における触媒金属の含有量は、白金が
1.0g/l,ロジウムが0.2g/lであった。Then, the alumina-coated catalyst carrier is immersed in a mixed aqueous solution of chloroplatinic acid and rhodium chloride having a predetermined concentration, pulled up, dried at 150 ° C. for 30 minutes, and further calcined at 500 ° C. for 45 minutes. . As described above, a catalyst is manufactured in which an alumina coat layer supporting platinum and rhodium as catalyst metals is provided on the surface of the catalyst carrier. The content of catalytic metal in this catalyst is
It was 1.0 g / l and rhodium was 0.2 g / l.
また、本発明の第２および第３実施例に係る排気ガス
浄化用触媒の製造法は、上記第１実施例の製造法におい
てアルミナスラリーを調整するとき、γ−アルミナ、ベ
ーマイトおよびアルミニウムの超微粉の各添加量がそれ
ぞれ第１表に示す如く異なるだけで、その他は同様な方
法で触媒を製造するものである。この場合、焼成後のア
ルミナコート層におけるアルミナ超微粉（アルミニウム
の超微粉が酸化反応したもの）の含有量は、アルミナ全
重量に対し、第２実施例では約5wt％であり、第３実施
例では約40wt％である。In addition, the method for manufacturing the exhaust gas purifying catalysts according to the second and third embodiments of the present invention, when adjusting the alumina slurry in the manufacturing method of the first embodiment, γ-alumina, boehmite, and ultrafine powder of aluminum. The catalysts are produced in the same manner except that the addition amounts of the above are different as shown in Table 1. In this case, the content of the alumina ultrafine powder (those obtained by the oxidation reaction of the aluminum ultrafine powder) in the alumina coat layer after firing was about 5 wt% in the second embodiment with respect to the total weight of alumina. Is about 40 wt%.
次に、上記各実施例の製造法による効果を述べるに先
立って、これらとの比較のための４つの製造法について
述べる。 Next, prior to describing the effects of the manufacturing methods of the above-described respective examples, four manufacturing methods for comparison with these will be described.
第１および第２比較例に係る触媒の製造法は、上記第
１実施例の製造法においてアルミナスラリーを調整する
とき、γ−アルミナ、ベーマイトおよびアルミニウムの
超微粉の各添加量が第１表に示す如く異なるだけで、そ
の他は同様な方法で触媒を製造するものである。この場
合、焼成後のアルミナコート層におけるアルミナ超微粉
の含有量は、アルミナ全重量に対し、第１比較例では約
3wt％であり、第２比較例では約60wt％である。In the method for producing the catalysts according to the first and second comparative examples, when the alumina slurry was prepared in the production method of the first example, the addition amounts of γ-alumina, boehmite, and ultrafine powder of aluminum are shown in Table 1. Others produce the catalyst in a similar manner, only as indicated. In this case, the content of the ultrafine alumina powder in the alumina coat layer after firing was about 1% with respect to the total weight of alumina in the first comparative example.
It is 3 wt%, and is about 60 wt% in the second comparative example.
また、第３比較例に係る触媒の製造法は、上記第１実
施例の如くアルミニウムの超微粉を添加することなく、
アルミナスラリーを調整するものである。すなわち、γ
−アルミナ70g、ベーマイト70g、水200ccおよび濃硝酸
1.6ccをホモミキサーにより５時間混合撹拌してアルミ
ナスラリーを調整する。そして、このアルミナスラリー
に、第１実施例の場合と同一のハニカム型触媒担体を浸
漬して引き上げた後、余分のスラリーを高圧エアブロー
で除去し、130℃で１時間乾燥し、さらに550℃で1.5時
間焼成をする。次いで、このアルミナコートを施した触
媒担体を、所定の濃度の塩化白金酸および塩化ロジウム
の混合水溶液に浸漬して引き上げた後、150℃で30分間
乾燥し、さらに550℃で1.5時間焼成をする。尚、このよ
うな方法で製造された触媒における白金およびロジウム
の含有量は、上記第１実施例の触媒の場合と同じで、白
金が1.0g/l、ロジウムが0.2g/lであった。In addition, the method of manufacturing the catalyst according to the third comparative example does not require addition of ultrafine aluminum powder as in the first embodiment described above.
It is for adjusting the alumina slurry. That is, γ
-70 g alumina, 70 g boehmite, 200 cc water and concentrated nitric acid
An alumina slurry is prepared by mixing and stirring 1.6 cc with a homomixer for 5 hours. Then, in this alumina slurry, the same honeycomb type catalyst carrier as in the case of the first embodiment was dipped and pulled up, the excess slurry was removed by high pressure air blow, dried at 130 ° C. for 1 hour, and further at 550 ° C. Bake for 1.5 hours. Next, this alumina-coated catalyst carrier is immersed in a mixed aqueous solution of chloroplatinic acid and rhodium chloride having a predetermined concentration, pulled up, dried at 150 ° C. for 30 minutes, and further calcined at 550 ° C. for 1.5 hours. . Incidentally, the contents of platinum and rhodium in the catalyst produced by such a method were the same as those in the case of the catalyst of the first embodiment, platinum was 1.0 g / l and rhodium was 0.2 g / l.
さらに、第４比較例に係る触媒の製造法は、上記第３
比較例における焼成条件（焼成温度が550℃で焼成時間
が1.5時間）を、上記第１実施例の場合における焼成条
件（焼成温度が500℃で焼成時間が45分間）に変えるだ
けで、その他は第３比較例と同様な方法で触媒を製造す
るものである。Further, the method for producing the catalyst according to the fourth comparative example is the same as the above
Only by changing the firing conditions in the comparative example (the firing temperature is 550 ° C. and the firing time is 1.5 hours) to the firing conditions in the case of the first embodiment (the firing temperature is 500 ° C. and the firing time is 45 minutes), A catalyst is manufactured by the same method as in the third comparative example.
そして、上記第１〜第３実施例および第１〜第４比較
例の製造法で各々製造された触媒について、排気ガス発
生装置を用い、以下の条件でライトオフ性能試験および
高温性能試験を行った。ここで、ライトオフ性能試験と
しては、排気ガスの温度を徐々に上昇（30℃/min）さ
せ、排気ガスの浄化率が50％になったときの温度を測定
した。また、高温性能試験としては、排気ガスの温度が
400℃のときの浄化率を測定した。Then, with respect to the catalysts produced by the production methods of the first to third examples and the first to fourth comparative examples, a light-off performance test and a high temperature performance test were performed under the following conditions using an exhaust gas generator. It was Here, as the light-off performance test, the temperature of the exhaust gas was gradually increased (30 ° C./min) and the temperature at which the purification rate of the exhaust gas reached 50% was measured. Also, as a high temperature performance test, the temperature of the exhaust gas
The purification rate at 400 ° C was measured.
試験条件； 空燃比（空気量／燃料量） 14.7 振幅 ±0.9 周波数 1.0Hz 空間速度 60000hr-1 触媒体積 24.0cc ライトオフ性能試験の測定結果は第２表に示し、高温
性能試験の測定結果は第３表に示す。この第２表および
第３表中におけるFreshの項は、電気炉を用いて550
℃で１時間加熱処理をした触媒についての測定結果であ
り、またAgedの項は900℃で80時間加熱処理をした
触媒についての測定結果である。Test conditions: Air-fuel ratio (air amount / fuel amount) 14.7 Amplitude ± 0.9 Frequency 1.0Hz Space velocity 60000hr -1 Catalyst volume 24.0cc The measurement result of the light-off performance test is shown in Table 2, and the measurement result of the high temperature performance test is the first. It is shown in Table 3. The Fresh term in Tables 2 and 3 is 550 using an electric furnace.
The measurement results are for the catalyst that has been heat-treated at 1 ° C. for 1 hour, and the Aged term is the measurement results for the catalyst that has been heat-treated at 900 ° C. for 80 hours.
また、上記浄化性能試験とは別に、各触媒について剥
離試験を行ったが、この試験の測定結果は図面のグラフ
に示す。ここで、剥離試験としては、直径３インチ、高
さ３インチの円筒形テストピースを600℃で30分間加熱
し、次に25℃の水中で冷却するという手順を３回繰り返
した後、十分乾燥し、剥離量を測定する方法を採用し
た。また、図面のグラフにおける縦軸の剥離率は、試験
前のアルミナコート付着率と試験後のアルミナコート付
着量との差を試験前のアルミナコート付着量で除した値
であり、横軸のアルミナ超微粉の含有量は、アルミナコ
ート層のアルミナ全重量に対するアルミナ超微粉の重量
割合である。 Separately from the above-mentioned purification performance test, a peeling test was performed for each catalyst, and the measurement results of this test are shown in the graph of the drawing. Here, as the peeling test, a cylindrical test piece with a diameter of 3 inches and a height of 3 inches was heated at 600 ° C for 30 minutes and then cooled in water at 25 ° C. This procedure was repeated 3 times and then dried sufficiently. Then, the method of measuring the amount of peeling was adopted. The peeling rate on the vertical axis in the graph of the drawing is a value obtained by dividing the difference between the alumina coat adhesion rate before the test and the alumina coat adhesion quantity after the test by the alumina coat adhesion quantity before the test, and the alumina axis on the horizontal axis. The content of ultrafine powder is the weight ratio of the alumina ultrafine powder to the total weight of alumina in the alumina coat layer.
第２表および第３表において、本発明の各実施例と第
３・第４比較例とを比較すると、本発明の各実施例の場
合には、触媒のライトオフ性能および高温性能がHC,CO,
NOxのいずれについも比較例の場合よりも大幅に向上
し、浄化性能および高温耐久性の向上を効果的に図り得
ることが判る。このように、本発明の各実施例の場合に
おいて触媒の浄化性能および高温耐久性の向上を図り得
る理由としては、第１に、アルミナコート層において触
媒金属を担持するアルミナにアルミナの超微粉が所定の
割合で含まれているため、このアルミナ超微粉におけ
る、粒子径が均一かつ微小で比表面積が非常に大きく、
また表面活性が強いという特性に基づいて、アルミナ超
微粉と触媒金属粒子との界面を通しての相互作用が強く
なり、触媒金属の活性および選択性が改善させること。
第２に、アルミナ超微粉の結晶状態が安定なものである
ため、熱による比表面積および細孔容積の低下が少ない
ことによるものと考えられる。In Tables 2 and 3, comparing each example of the present invention with the third and fourth comparative examples, in the case of each example of the present invention, the light-off performance and the high temperature performance of the catalyst were HC, CO,
It can be seen that any of the NOx is greatly improved as compared with the case of the comparative example, and the purification performance and the high temperature durability can be effectively improved. As described above, the reason why the purification performance and the high temperature durability of the catalyst can be improved in each of the examples of the present invention is, firstly, that the ultrafine powder of alumina is added to the alumina carrying the catalyst metal in the alumina coat layer. Since it is contained in a predetermined ratio, in this alumina ultrafine powder, the particle size is uniform and minute, and the specific surface area is very large,
Further, based on the property that the surface activity is strong, the interaction between the ultrafine alumina powder and the catalyst metal particles through the interface is strengthened to improve the activity and selectivity of the catalyst metal.
Secondly, it is considered that the crystal state of the ultrafine alumina powder is stable, and thus the specific surface area and the pore volume are less likely to decrease due to heat.
また、第３比較例と第４比較例とを、触媒の浄化性能
について比較するに、第３比較例の場合の浄化性能は、
本発明の各実施例の場合のそれよりも劣るが、第４比較
例の場合よりもよい。この第３比較例と第４比較例と
は、触媒の製造法における焼成条件（焼成温度および焼
成時間）のみが異なるだけであり、第４比較例の場合に
おける焼成条件は本発明の第１実施例の場合と同一であ
るが、第３比較例の場合、第４比較例および本発明の第
１実施例の場合よりも焼成温度が高く、また焼成時間も
長くなっている。このことは、本発明の第１実施例の如
く、アルミニウムの超微粉を所定の割合で添加混合した
アルミナスラリーでもって触媒担体にアルミナコートを
施す場合、触媒の浄化性能等を高めることができるだけ
でなく、触媒の製造工程における焼成温度を低く、かつ
焼成時間を短くすることができ、製造の簡易化や迅速化
を図ることができる。Further, comparing the third comparative example and the fourth comparative example with respect to the purification performance of the catalyst, the purification performance in the case of the third comparative example is as follows.
Although it is inferior to that of each example of the present invention, it is better than that of the fourth comparative example. The third comparative example and the fourth comparative example are different only in the calcination conditions (calcination temperature and calcination time) in the catalyst production method, and the calcination conditions in the case of the fourth comparative example are the same as those of the first embodiment of the present invention. Although the same as the case of the example, in the case of the third comparative example, the firing temperature is higher and the firing time is longer than those of the fourth comparative example and the first embodiment of the present invention. This means that, as in the first embodiment of the present invention, when the alumina support is coated on the catalyst carrier with the alumina slurry in which the ultrafine powder of aluminum is added and mixed at a predetermined ratio, the purification performance of the catalyst can be improved. In addition, the calcination temperature in the catalyst manufacturing process can be lowered and the calcination time can be shortened, so that the manufacturing can be simplified and speeded up.
さらに、第２表および第３表において、本発明の各実
施例と第１・第２比較例とを比較するに、第１比較例の
場合の浄化性能は、他のそれよりも劣ることが判る。ま
た、図面のグラフから判るように、アルミナコート層に
おけるアルミナ超微粉の含有量がアルミナ全重量に対し
40〜50wt％以上になると、剥離率が急激に増加する。従
って、アルミニウムの超微粉を添加混合したアルミナス
ラリーでもって触媒担体にアルミナコートを施す際、該
アルミニウムの超微粉は、焼成後のアルミナコート層に
おけるアルミナ超微粉（アルミニウムの超微粉が酸化反
応したもの）が本発明の各実施例の如くアルミナ全重量
に対し５〜50wt％を占める割合で添加することが好まし
い。つまり、アルミナ超微粉の含有量が5Wt％以下であ
る（第１比較例の場合が相当する）と、このアルミナ超
微粉により浄化性能を高めるなどの効果が十分に得られ
ない。また、アルミナ超微粉の含有量が50wt％以上であ
る（第２比較例の場合に相当する）と、アルミナコート
層の触媒担体に対する密着性および触媒金属の担持力が
著しく低下することなどによって、剥離が生じ易く、耐
久性が悪くなる。Further, in Tables 2 and 3, comparing each example of the present invention with the first and second comparative examples, the purification performance in the case of the first comparative example may be inferior to that of other examples. I understand. Also, as can be seen from the graph in the drawing, the content of the ultrafine alumina powder in the alumina coat layer is relative to the total weight of the alumina.
When it is 40 to 50 wt% or more, the peeling rate sharply increases. Therefore, when the alumina support is applied to the catalyst carrier with the alumina slurry to which the ultrafine aluminum powder is added and mixed, the ultrafine aluminum powder is the ultrafine alumina powder in the alumina coat layer after firing (the ultrafine aluminum powder is oxidized and reacted. ) Is preferably added in a proportion of 5 to 50 wt% with respect to the total weight of alumina as in each of the examples of the present invention. That is, when the content of the ultrafine alumina powder is 5 Wt% or less (corresponding to the case of the first comparative example), the effect of enhancing the purification performance cannot be sufficiently obtained by the ultrafine alumina powder. Further, when the content of the alumina ultrafine powder is 50 wt% or more (corresponding to the case of the second comparative example), the adhesion of the alumina coat layer to the catalyst carrier and the carrying ability of the catalyst metal are remarkably reduced, Peeling easily occurs, resulting in poor durability.
次に、上記第１実施例の触媒の製造法のように、アル
ミニウムの超微粉を添加混合したアルミナスラリーでも
って触媒担体にアルミナコートを施す際、該アルミニウ
ム超微粉の平均粒径を如何に定めるべきか検討するため
に、第４・第５実施例および第５比較例としてアルミニ
ウム超微粉の平均粒径を種々変えた。すなわち、第４実
施例に係る触媒の製造法では、平均粒径が1000Åのアル
ミニウム超微粉を使用し、第５実施例に係る触媒の製造
法では、平均粒径が5000Åのアルミニウム超微粉を使用
した。一方、第５比較例に係る触媒の製造法では、平均
粒径が7000Åのアルミニウム超微粉を使用した。尚、第
４・第５実施例および第５比較例の製造法は、アルミニ
ウム超微粉の平均粒径が異なる以外は第１実施例の製造
法と全く同じであり、アルミナスラリーを調整する際の
γ−アルミナ、ベーマイトおよびアルミニウム超微粉の
各添加量等も同じである。Next, as in the method of producing the catalyst of the first embodiment, when the alumina support is coated on the catalyst carrier with the alumina slurry to which the ultrafine aluminum powder is added and mixed, how to determine the average particle size of the ultrafine aluminum powder In order to investigate whether it should be done, the average particle size of the ultrafine aluminum powder was variously changed as the fourth and fifth examples and the fifth comparative example. That is, in the method for producing a catalyst according to the fourth example, ultrafine aluminum powder having an average particle size of 1000Å is used, and in the method for producing a catalyst according to the fifth example, ultrafine aluminum powder having an average particle size of 5000Å is used. did. On the other hand, in the method for producing the catalyst according to the fifth comparative example, ultrafine aluminum powder having an average particle size of 7,000Å was used. The manufacturing methods of the fourth and fifth examples and the fifth comparative example are exactly the same as the manufacturing method of the first example except that the average particle size of the ultrafine aluminum powder is different. The amounts of γ-alumina, boehmite, and ultrafine aluminum powder added are the same.
そして、上記第４・第５実施例および第５比較例の製
造法で各々製造された触媒について、上記第１実施例の
製造された触媒の場合と同様のライトオフ性能試験およ
び高温性能試験を行った。ライトオフ性能試験の測定結
果は第４表に示し、高温性能試験の測定結果は第５表に
示す。この第４表および第５表から判るように、第４・
第５実施例の場合の浄化性能は、第１実施例の場合の浄
化性能と同程度に高められるが、第５比較例の場合の浄
化性能は、これらの浄化性能に比べて低くなる。従っ
て、アルミニウムの超微粉を添加混合したアルミナスラ
リーでもって触媒担体にアルミナコートを施す際、該ア
ルミニウム超微粉の平均粒径は、本発明の実施例の如く
5000Å以下にすることが好ましく、最適粒径は1000Å以
下である。Then, with respect to the catalysts respectively manufactured by the manufacturing methods of the fourth and fifth examples and the fifth comparative example, the same light-off performance test and high temperature performance test as in the case of the manufactured catalyst of the first embodiment were conducted. went. The measurement results of the light-off performance test are shown in Table 4, and the measurement results of the high temperature performance test are shown in Table 5. As can be seen from Tables 4 and 5,
The purification performance in the case of the fifth embodiment is enhanced to the same extent as the purification performance in the case of the first embodiment, but the purification performance in the case of the fifth comparative example is lower than these purification performances. Therefore, when the catalyst carrier is coated with alumina using an alumina slurry to which aluminum ultrafine powder is added and mixed, the average particle diameter of the aluminum ultrafine powder is the same as in the embodiment of the present invention.
The particle size is preferably 5000 Å or less, and the optimum particle size is 1000 Å or less.
（発明の効果） 以上の如く、本発明における排気ガス浄化用触媒の製
造法によれば、平均粒径が5000Å以下のアルミニウムの
超微粉を添加混合したアルミナスラリーに触媒担体を浸
漬して、触媒担体の表面に、アルミナの超微粉がアルミ
ナ全重量の５〜50重量％を占めるコート層を得るように
したことによって、アルミナ超微粉の特性により触媒金
属の活性および選択性を改善して触媒の触媒性能を効果
的に高めることができるとともに、焼成時間を短縮しか
つ焼成温度を低下させて、製造の簡略化を図ることがで
きる。しかも、コート層の触媒担体に対する密着性およ
び触媒金属の担持力を十分に確保して熱影響による剥離
を防止することができ、触媒の耐久性の向上を図ること
ができる。 (Effect of the invention) As described above, according to the method for producing an exhaust gas purifying catalyst of the present invention, the catalyst carrier is immersed in an alumina slurry in which ultrafine aluminum powder having an average particle size of 5000 Å or less is added and mixed to form a catalyst. By providing a coating layer on the surface of the carrier, in which the ultrafine alumina powder occupies 5 to 50% by weight of the total weight of the alumina, the activity and selectivity of the catalyst metal are improved by the characteristics of the ultrafine alumina powder to improve the catalytic property. The catalyst performance can be effectively enhanced, and the firing time can be shortened and the firing temperature can be lowered to simplify the production. Moreover, the adhesion of the coat layer to the catalyst carrier and the supporting ability of the catalyst metal can be sufficiently secured to prevent the peeling due to the thermal influence, and the durability of the catalyst can be improved.
図面は剥離試験の測定結果を示すグラフである。 The drawing is a graph showing the measurement results of the peel test.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｂ０１Ｊ 37/02 ＺＡＢ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location B01J 37/02 ZAB
Claims (1)
下のアルミニウムの超微粉をアルミナ全重量の５〜50重
量％を占める割合で添加混合し、このアルミナスラリー
に触媒担体を浸漬し、焼成をした後、このアルミナコー
トを施した触媒担体を、触媒金属の水溶液に浸漬し、焼
成をすることを特徴とする排気ガス浄化用触媒の製造
法。1. Ultrafine powder of aluminum having an average particle size of 5000Å or less is added to and mixed with the alumina slurry in a proportion of 5 to 50% by weight of the total weight of alumina, and the catalyst carrier is immersed in the alumina slurry and calcined. After that, the catalyst carrier coated with this alumina is immersed in an aqueous solution of a catalyst metal and calcined, and a method for producing an exhaust gas purifying catalyst is characterized.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61310580A JPH0811197B2 (en) | 1986-12-25 | 1986-12-25 | Exhaust gas purification catalyst manufacturing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61310580A JPH0811197B2 (en) | 1986-12-25 | 1986-12-25 | Exhaust gas purification catalyst manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63162047A JPS63162047A (en) | 1988-07-05 |
| JPH0811197B2 true JPH0811197B2 (en) | 1996-02-07 |
Family
ID=18006947
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61310580A Expired - Lifetime JPH0811197B2 (en) | 1986-12-25 | 1986-12-25 | Exhaust gas purification catalyst manufacturing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0811197B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5200382A (en) * | 1991-11-15 | 1993-04-06 | Exxon Research And Engineering Company | Catalyst comprising thin shell of catalytically active material bonded onto an inert core |
| JP4907108B2 (en) * | 2005-06-28 | 2012-03-28 | 株式会社キャタラー | Method for adjusting viscosity of slurry and coating slurry for exhaust gas purification catalyst |
-
1986
- 1986-12-25 JP JP61310580A patent/JPH0811197B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63162047A (en) | 1988-07-05 |
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