Title of Invention

"A CATALYST SUPPORT FOR EXHAUST GAS PURIFICATION".

Abstract The present invention intends to provide the catalyst for exhaust gas purification which can keep down decrease of catalyst ability resulted from oxidation and corrosion of the support. The metal support catalyst Cor exhaust gas purification is comprised of a metal support 1 formed by an iron system metal foil or an iron system metal sheet, a supper cover film 2 formed on a surface of the metal support, a support layer 3 formed on a surface of the support cover film, and a catalyst matal supported on the support layer. In the metal support catalyst for exhaust gas purification, no peel-off of the support layer can extend life time of the catalyst.
Full Text BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to a metal support catalyst for exhaust purification which uses a metal support for purifying exhaust gas

discharged from an internal cc•mbust ion engine.

Related Backctround Art

In an automobile and a motor cycle, an exhaust gas purifying apparatus is used for purifying exhaust gas discharged from them. There are many types of the exhaust gas purifying apparatuses such as a thermal reactor type, a lean-burn type, an engine modification type and a catalyst type.

Among them, the catalyst type exhaust gas purifying apparatus has been widely used. It purifies exhaust gas by using a catalyst noble metal such as Pt (platinum), Rh (rhodium) and Pd (palladium). As a catalyst body for exhaust gas purification (referred simply catalyst for exhaust gas purification" hereinafter) for the exhaust gas purifying apparatus, the catalyst in which a support layer made of activate alumina ( V -alumina) is formed on a surface of the catalyst support, and a noble metal catalyst is supported on the support layer haB been used.

The catalyst for exhaust gas purification is classified, depending on shape of the catalyst support, into monolith shape, grain shape or pipe shape. Heat—proof materials such as a ceramics including cordierite and a heat-proof metal including stainless have been used for the catalyst support, since it is exposed in exhaust gas of high temperature and needs to have heat-proof character.

The catalyst support made of ceramics is weak against mechanical shock applied thereto) and has large exhausting resistance.

For this reason, to decrease pressure loss in the exhaust system and
to increase heat-proof character of the support) the catalyst support made of metal (metal support) have been used.

In the catalyst for exhaust gas purification using the metal support, the metal support is formed by rolling a steel member such as austenitic system stainless steel SuS 304 (l8Cr—SNi) or ferrite system stainless steel sus 430 (16 Cr ferrite system stainless steel) into a foil or a sheets and by manufacturing it into a metal support. On a surface of the metal support: the support layer is formed, and the catalyst metal is supported on the support layer. -

However, in the catalyst for exhaust gas purification using the metal support, the catalyst metal supported on the surface of metal support may corrode the metal support due to catalyst activation thereof. As a result, purifying ability of the catalyst for exhaust gas purifying may be deteriorated.

In detail, due to direct supporting of the support layer and the catalyst metal on the catalyst support, the metal support may be oxided and corroded by activate operation of the catalyst metal. The oxide of the metal support (iron oxide) invades into the support layer and the catalyst metal, to deteriorate catalyst activation of the catalyst metal Also, corrosion of the metal support causes peel-off of the support layer supporting the catalyst metal thereon.

in addition, when the metal support is formed by a conventional steel member to which elements such as Cr etc. have not been added, the above oxidation and corrosion of the metal support easily occurs. Oxidatin and corrosion occur by only leaving the metal support on which the support layer and the catalyst metal are supported, to make usage of the matal support as the catalyst support impossible.

In particular, exhaust gas discharged from the internal combustion engine of the motor cycle, containing relatively much

water, has oxidmg character. For this reason, the catalyst for exhaust gas purification using the metal has been suffering from corrosion of the metal support caused by exhaust gas of oxide character.

SUMMARY OF THE INVENTION


The present invention is made in view of the above circumstances and intends to provide a metal support catalyst for exhaust gas purification in which deterioration of catalyst ability of the metal support due to oxidation and corrosion thereof is reduced.

In order to overcome problem in the prior art, inventors noticed contracting of the support layer and the catalyst metal with oxided component of the metal support causes corrosion of the metal support. They studied manner or way to avoid direct contacting of the metal support with the support layer and the catalyst metal. As a result, they found out the above problem can be overcome by supporting the catalyst metal on the surface of catalyst support via a support cover film.

The present invention relates to a catalyst ..tor exhaust gas purification of:
comprise a metal support formed by an iron system metal foil or an iron system metal sheet;
- a support cover film formed on surface of said metal support,
- a support layer formed on a surface of said support cover film and
- a catalyst metal supported on said support layer.

In the metal support catalyst for exhaust gas purification, the catalyst support will contact with the catalyst metal directly since it covered the surface thereof by the support cover film. Thus, no corrosion will occur in the metal support. As a result, the metal support catalyst for exhaust gas purification not suffering from decrease of exhaust gas purifying ability can maintain good purifying ability for long time.


The metal support cataLyst for exhaust gas purific'ati.on of the present invention can have various embodying modes to be explained below.

(i) The metal support is formed by an iron system metal foil or an iron system metal sheet. The iron system metal forming the metal foil or metal sheet means a metal containing iron as main component and having sufficient characteristic as the metal support. In addition to stainless (SUS4O3, sus436) having been conventionally used for the metal catalyst, a popular steel material such as a cold—rolled steel plate (SPCC) can be used for such iron system metal.

The metal support, can have various shapes according to usage thereof. or example, it can have a honeycomb body in which flat plates formed by the metal foil etc. and wave plates are accumulated alternately, or a honeycomb body in which the flat plates and the wave plates are accumulated and rclJ.ed to a roller shape. Containing the honeycomb body in an outer cylinder can maintain a mechanical strength thereof. The outer cylinder can be formed by a metal sheet having the same composition as that of the honeycomb body. The honeycomb body and the outer cylinder can be unified by the conventional manner. In all cases, thickness of the metal foil and the metal sheet can be determined corresponding to usage thereof.

Also, the metal support can have a pipe shape formed by deforming a metal sheet or metal foil. A support plate of cross-shape or wave-8hape can be added to divide an inner space of the metal catalyst.

(ii) The support cover film covers surface of the metal support. It prevents the metal support from directly contacting the support layer and the catalyst metal supported thereon. ThuS, the metal support is not corroded by the catalyst metal. Here1 the Bupport cover film is preferably formed by substance having oxide—proof character.

The support cover fiJ.m is preferably made of nickel and chromium. That is, even when the catalyst for exhaust gas purification becomco oxiding dtmOBphere, a passive state layer (oxide cover film) for which nickel and chromium performs the oxide-proof character is formed between the support layer and the metal support. Thus, the metal support is prevented from oxidation.
Nickel and chromium are preferably contained in the support cover film by 50 to 70 wt% and 3 to 50 wt%, respectively. Here, "wt%' means rate of nickel and chromium provided that the whol, support cover film has 100 wt%.
The support cover filim made of "a soldering (brazing) material" which means a non—iron metal Used for brazing a metal material, or an alloy thereof. For example, the soldering material containing Ni as main part, and 18 wt% Cr and 10 wt% Si; or the soldering material containing Ni as main part, and 6 wt% Cr and 4 wt% Si, can be adopted. The soldering material can, due to good intimate with a metal material1 be applied to surface of the metal support uniformly. In addition, the support cover film made of the soldering material covers surface of the metal support strongly. The cover film m made of the soldering material can be formed by heating the soldering material on surface of the metal support easily.

Forming the metal cover film by the soldering material having high heat transmitting character can diffuse heat of exhaust gas.

Thus, exhaust gas purifying ability of the catalyst is not deteriorated by heat of exhaust gas. The support cover film preferably has thickness not less than 3 u m. When thickness of the support cover film is Bmaller than 3 urn, the metal catalyst may be oxided at an area corresponding to the thin part, so that ~e oxide may invade J.nto the support layer.

(iii) The !upport layer is formed on surface of the support cover fili
to increase contact area Of the catalyst with exhaus: gas.

Conventional support layer, for example such as heat-proof inorganic oxide can be used. Among them, the heat—proof inorganac oxide conta.ning activated alumina as main component is preferable. Also, the support layer preferably contains oxide of cerium or zironium to increase the exhaust gas purifying character of the catalyst. Layer thickness of the support layer is not restricted but can be determined according to usage thereof.

(iv) The catalyst metal is supported on the support layer. It can be supported on the support layer having been formed, or can be added to the metal support by mixing it into slurry made of activate alumina forming the support layer. The catalyst metal purifies exhaust gas in the catalyst. The conventional catalyst metals such as oxiding catalyst, reducing catalyst or there—way catalyst having been used for purifying exhaust gas can be used.

In detail, using at least one of Platinum (Pt), Palladium (Pd) and Rhodium (Rh) as the catalyst metal can effective.y remove carbonnionooxided (CO), hydrocarbon (HC) and nitrogenoxide (NOX). contained in exhaust gas. Supported amount of the catalyst tuetalon the support layer is not restricted but suitably selected according to usage thereof.

(Manufacturing of Metal Support Catalyst for. Exhaust Gas Purirication)

The metal support catalyst for exhaust gas purification of the present invention can be manufactured by forming the support layer on the support cover film formed on the metal support, and then supporting the catalyst metal on the support layer. Instead of it, the metal support catalyst can be manufactured by mixing the catalyst metal into slurry forming the support layer, and then coating slurry on the support cover film.
In detail, the metal support is formed into a predetermined shape. That is, a metal plate made of foil-like or sheet-like iron system metal is worked to form a catalyst support. Next, the support cover film is formed on the metal support formed. The support cover fZm wade of soldering material is preferably formed by heating the scldering material mounted on surface of the metal support, for example in vacuum atmosphere. Heating under vacuum atmosphere prevents elements contained in surrounding atmosphere from being ccntained in the cover film to be formed. Needless to say, the scldering material is heated in temperature high enough to be melted.

Thenafter, the support layer is formed on the support cover film on which the catalyst metal is supported in the conventional manner. That is, the slurry of inorganic oxide of heat-proof caracter forming the support layer is prepared. Then, it is coated on surface of the support cover film, and dried and baked.

The catalyst metal is supported on the support layer by

dipping the catalyst support supporting the support layer thereon into solution containing the catalyst metal. The catalyst support dried and baked becomes the catalyst for exhaust gas purification.

On the other hand, the catalyst metal is supported on the support layer by forming a mixed slurry in which the catalyst metal is mixed into the slurry made of heat-proof inorganic oxide forming the support layer, and by coating the mixed slurry on surface of the support cover film.

On account of the support cover film formed between the support layer and catalyst metal, and the metal support, the catalyst for exhaust gas purification of the present invention does not suffer from corrosion of the metal support by activate operation of the catalyst metal. As a result, the catalyst, not suffering from deteriorated catalyst ability, can have long life. Also, the catalyst can use the


cr.eap conventional steel material as the metal support, because restriction of activate operation of the catalyst metal by the support cover film excludes the o~cide-procf character etc. of the metal support.

The catalyst for exhaust ga~ purification of the present. invention, excellent in oxide—proof character) is suitably used tor t:~e motor cycle i~,hich may discharge exhaust gas of oxide atmosphere.

Brief Explanation of the Drawings

Fig. I iB ~ schematic sectional view of the pipe-shaped catalyst of tI'ie embodiment 1.

Preferred Embodiment of the Invention

Preferred embodi.ment:3 of the present invention will be explained with reference to attached drawings. in the all embodiment, the catalysts for exhaust gas purification are manufactured by using & pipe-shaped metal support made of iron 5yetem metal.


As shown in Fig. 1, a catalyst for exhaust gae pQrification of

the embodiment 1 is comprised of a pipe-Bhaped metal support

support cover film 2 made of soldering material and soldered to an

inner surface of the metal Bupport 1 to cover it, a support layer 3

formed on a surface of the support cover film 2~ and a catalyst metal

(not shown) supported on the support cover film 3.

As the metal support, a pipe made of SPCC (cold-rolled steel plate) and having thickness of 1.5 mm, inner diameter of 30 nim, and capacity of 100 1 is used. Here, capacity means volume of inner space of the pipe. The pipe put into market and made of SPCC is cut by a predeten~iined length to obtain the above pipe.

A 5oldering mate~ia1 including, ~i as main part, Cr 18 wt% and Si 10 wt~ are used for forming the support cover film. The 5upport layer is formed by heat-proof inorganic oxide containing activate

al~mina as main component, and is supported on the support cover film by Thickness of 30 am. Pt of 5 wt% and Rh of 1 wt% are supported in the catalyst as the catalyst metal, respectively.

Next, manufacturing method of the pipe—shaped catalyst of the embodiment 1 will be explained..

The metal support made of SPCC and sprayed on the inner peripheral surface thereof the soldering inateria]. by thickness of 10 to 100 ~.m is set in vacuum atmosphere at 1200 '0 for 1 hour. Thus, the support cover film is formed on surface of the metal support.

Thenafter, the activate alumina, binder and water of respectively predetermined weight are mixed uniformly to prepare the slurry as the support layer. The metal support coated with the prepared slurry is dried. Solution of catalyst metal is impregnated ir~to the dried suppurL layer to attach noble metal thcrcto. Then, the metal support is baked at 250 '0 for 1 hour.



A catalyst for exhaust gas purification of the embodiment 2

has same construction that of the above embodiment 1, except that a

metal support is made of SuS 304. It is manufactured by the same

izethod as that of the embodiment 1.
A catalyst for exhaust gas purification of the embodiment 3

haB same construction that of the above embodiment 1, except that a metal support is made of SUS 436L. It is manufactured by the same method as that of the embodiment 1.



~i catalyst for exhaust gas purification of the embodiment 4 uses a punched pipe as the metal support. Catalyst component is applied to an inner peripheral surface and an outer peripheral surface of the punched pipe. In detail, the pipe made of sus 304 and has

thickness of 1.0 ~, inner c.iameter of 25 mm and capacity of 150 1 is used for the catalyst support. Holes having diameter of 3 mm are formed staggerly by interval of 6 mm. The soldering material containinq Ni. as main part, and Cr 6 wt~ and Si 4 wt% is used to form the support cover rum.

The catalyst of the embodiment 4 is manufactured by applying the support cover film onto surface of the metal support made of punched pipe, and formir~g :he catalyst component on surface of the inner and outer peripheral iurfaces of the metal support. The support cover film nade of solderincr material and has thickness of 50 to 200 gi m is coated on surface o~ the metal support, then the coated metal support is held at 1000 hour.

On the inner and c'ut'ar peripheral surfaces of the metal support ~&tG with Llii~ bupport cc.vcr film, the slurry mama AR that in the ~inbodiments 1 to 3 is sprayed and dried to form the support layer.

Next, catalyst metal solution prepared in the same mni~Br as that of the embodiment. I to 3 is impregnated into the support layer. Then the metal support is baked &t 250 '0 for 1 hour.



A catalyst for exhaust gas purification of the comparative sample 1 is same as that in the embodiment 2, except that no support cover film is formed betweiRn the metal support and the support layer That is, on the inner peripheral surface of the metal support, the support layer and catalyst metal are directly applied. ror manufacturing the catalyst of the comparative sample 1, the mupport layer is formed on the inner peripheral surface of the pipe—shaped metal support of the embodiment 2 directly, and the catalyst metal is formed on the support layer. For the metal Support, support layer andg catalyst metal, materials used in the embodiment 2 are used.

(Comparative Sample 2>
A catalyst for exha.~st gas purification of the comparative sample ~ is a pipe-shaped cat&Lyst in which a layer of soldering material 1. formed on surfac:e of a metal support, and a support layer and a cata.yst metal are apE.lied to surface of the soldering material layer. flare, tbe solderinq material layer being contacted with surface of the metal support. and not soldered thereto should be noted.

For manufacturing the catalyst of the comparative sample 2, the soldering material is coated on the inner surface of the pipe-shaped metal support of the einj~o~iment 2 by thickness of 10 to 100 gi a. Then, the coated metal support i.s held in the drier under atmospheric circumstance at 250 '0 for 1 hour. As a result, bindez~ component contained in the soldering material vapors to leave metal component contained therein on surface of the metal support. Here, metal couponent attaches to surface of the metal support in particle atate~ Then, the support layer is formed on surface of the coated metal support, and the catalyst metal is supported on the support layer, in the maine manner as that in t~ie embodiment 2.

For evaluating the catalysts for exhaust gas purification of the embodiments, 1 to 4, and the comparative samples 1 to 2, an evaluation teat is pe~for~d. In the evaluation test, catalysts are disposed in a furnace of high temperature into which two kinds of test gas are introduced alterrutely and repeatedly to examine endurance character. In detail, the furnace is kept inner temperature thereof at 900 '0. Gas containing 10% H z 0, 1% 0 and balancing H z, and gas containing 10~ rHO, 1% Co and balancing Na are alternately introduced into the fu.r-nace by interval of 60 SQCOfldB. Alternate gas introduction continued t~r 5 hours. The catalyst is evaluated by observing appearance thernof visually. Each catalyst is evaluated in oxide-proof character and peel-proof character.
Results of evaluation are shown in a following Table 1. In column of the oxide-proof character~ symbol 0 means metal oxide riaving not invaded into thE~ support layer1 L~ means the metal oxide

having partially invaded into the support layer1 and ~ means the metal oxide having covered surface of the support layer. In column of the peel-proof character, 0 means there being no peel-oft of the support layer, and) means there being peel-off of the support layer.


As apparent from the above Table 1, all of the catalysts of the

embodiments 1 to 4 are excellent in the oxide—proof character to be hardly oxided. All of the catalysts, not having generated peel-of! of the support layer, do jiot suffering from corrosion of the metal support.

Summing up, all of the catalysts, due to excellence of the oxide-proof character, do not generat43 corrosion of the metal support, which in turn prevents pel—off of the support layer.

To the contrary, thi catalyst of the comparative sample 1 is bad in the oxide—proof character, and suffers from corrosion of the metal support and peel—ott of the lupport layer. The catalyst of the comparative sample 2 generates 5light oxidation of the metal support


and peel—off of ti~ support layer. In detail, in the catalyst of the comparative samp:1~ 1, due to forming of the B~tpport layer on surface of the metal support, the substance of oxide character can easily contact bJith the metal s~poort to oxide and corrode it~ thus, the supporting is peeled off. :n the catalyst of the comparative sample 2, the soldering materiaJ layer fo:rmed on surface of the metal support keeps down contacting ~t the sub:itance of oxide character with the metal Bapport, but it o~ zwt keep i~ni~m i-hA nontacting perfectly. br this reason, the catayst is s.ightly deteriorated in the oxide-proof character thereof.

Az mentioned above, in the metal support catalyst for exhaust gas purification ~f the present invention, the support layer and the catalyst metal are applied to the metal support made 0! the iron system metal via the support cover film formed on the metal support. The catalyst metal, ~ot contacting with the metal support, does riot corrode the meta support. As a result, peel—off of the Support layer due to corrosion ~f the meteLl Support does not occur, so that life time of the catalyst :an be extended. In addition, the metal support not contacting dith the catalyst component, needs not be made of material having oxide-proof character, but can be made of cheaper material such as the general steel plate.





We Claim

1. A catalyst tot exhaust gas purification comprised of:

- a metal support formed by an iron system metal foil or an iron system metal sheet;

- a support cover film formed on surface of said metal support.

- a support layer'formed on a surface of said support cover film and a catalyst metal supported on said support layer.

2. A catalyst tor exhaust gas purification as claimed in claim 1 wherein said support cover film is made of nickel and chromium.
3. A catalyst ~or exhaust gas purification as claimed in claim 2 wherein said support cover film includes nickel of 50 to 97 wt0/o, and chromium of 3 to 50

4. A catalyst for exhaust gas purification as claimed in claim 2 wherein said support cover film has thickness not less than 3 .~m.

5. A catalyst tor exhaust gas purification as claimed in claim I wherein said support cover film is made of a soldering material.

6. A catalyst tor exhaust gas purification as claimed in claim 5 whcrcin said support cover film includes nickel as main part, and 18 wt% Cr and 10 wt0/o Si.

7. A catalyst Eor exhaust gas purification as claimed in claim 5 wherein said support cover film includes nickel as main part and 6 wt% Cr and 4 wt 0/a Si

8. A catalyst for exhaust gas puritication as claimed in claim 5 wherein said support cover film has thickness nokiess than 3 tim.

9. A catalyst for exhaust gas purification substantially as herein described with reference to the accompanying drawings.

Documents:

050-del-2001-abstract.pdf

050-del-2001-claims.pdf

050-del-2001-correspondence-others.pdf

050-del-2001-correspondence-po.pdf

050-del-2001-description (complete).pdf

050-del-2001-drawings.pdf

050-del-2001-form-1.pdf

050-del-2001-form-19.pdf

050-del-2001-form-2.pdf

050-del-2001-form-3.pdf

050-del-2001-form-5.pdf

050-del-2001-pa.pdf

050-del-2001-petition-others.pdf


Patent Number 199530
Indian Patent Application Number 50/DEL/2001
PG Journal Number 51/2007
Publication Date 21-Dec-2007
Grant Date 26-Oct-2007
Date of Filing 19-Jan-2001
Name of Patentee CATALER CORPORATION
Applicant Address 7800, CHIHANA, DAITO-CHO, OGASA-GUN, SHIZUOKA-KEN, 437-1492, JAPAN.
Inventors:
# Inventor's Name Inventor's Address
1 KUBOAT AKIO C/O CATALER CORPORATION 7800, CHIHAMA, DAITO-CHO, OGASA-GUN, SHIZUOKA-KEN, 437-1492, JAPAN.
2 SHIRAHATA JUNYA C/O CATALER CORPORATION 7800, CHIHANA, DAITO-CHO, OGASA-GUN, SHIZUOKA-KEN, 437-1492, JAPAN.
3 SATO MASAYASU C/O CATALER CORPORATION 7800, CHIHANA, DAITO-CHO, OGASA-GUN, SHIZUOKA-KEN, 437-1492, JAPAN.
4 OZAWA TERUHIKO C/O CATALER CORPORATION 7800, CHIHANA, DAITO-CHO, OGASA-GUN, SHIZUOKA-KEN, 437-1492, JAPAN.
5 YOKOYAMA NAOKI C/O CATALER CORPORATION 7800, CHIHANA, DAITO-CHO, OGASA-GUN, SHIZUOKA-KEN, 437-1492, JAPAN.
PCT International Classification Number F01N 1/08
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA