Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And additional al or si containing component
Reexamination Certificate
1998-08-20
2001-03-27
Dunn, Tom (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
And additional al or si containing component
C423S213200, C423S239200, C423S713000
Reexamination Certificate
active
06207604
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an adsorbent suitably used for hydrocarbon adsorption and purification of the exhaust gas emitted from an automobile.
BACKGROUND ART
Catalysts used for purification of the exhaust gas emitted from automobiles, etc. must be heated to a desired temperature or higher by, for example, the heat of exhaust gas, in order to exhibit their catalytic activities. Therefore, when the temperature of exhaust gas is low as experienced during the cold start of engine, the harmful substances (HC, CO and NOx) in exhaust gas are hardly purified. HC, in particular, is discharged in a large amount during the cold start, and its purification is an important task to be achieved.
To improve the efficiency of HC purification during the cold start, a technique is known which comprises using, as a HC adsorbent, a molecular sieve made of a crystalline aluminosilicate (e.g. a zeolite) and allowing the adsorbent to adsorb and store HC until a catalyst reaches its operating temperature.
For example, an apparatus for purification of automobile exhaust gas, using Y zeolite or mordenite as a HC adsorbent is disclosed in Japanese Patent Application Kokai (Laid-Open) No. 75327/1990. Also in Japanese Patent Application Kokai (Laid-Open) No. 293519/1992 is asserted use of an adsorbent obtained by subjecting H
+
/ZSM-5 zeolite to ion exchange with Cu and Pd, in order to alleviate the adverse effect by water adsorption and achieve higher HC adsorption capability and wider temperature range allowing for HC adsorption. For the same purpose, use, as an adsorbent, of a pentasil type metalosilicate subjected to ion exchange with H, Cu or Pd is proposed in Japanese Patent Application Kokai (Laid-Open) No. 63392/1994.
Zeolites, etc. heretofore used as a HC adsorbent, however, are inferior in heat resistance, particularly in heat resistance in a moisture-containing atmosphere (e.g. an automobile exhaust gas), i.e. hydrothermal resistance, as compared with alumina, etc. used as a carrier of ordinary catalyst for automobile exhaust gas purification; therefore, there has been a fear that they deteriorate when used at high exhaust gas temperatures such as experienced in continuous high speed driving of automobile.
Use of zeolite particularly in an in-line type exhaust gas purification system (which uses no bypass for high temperature exhaust gas and has a simple structure) has been fairly severe to ordinary zeolite.
The present invention has been completed in view of the above-mentioned problem of the prior art. The object of the present invention is to provide an adsorbent suitably usable in applications where the adsorbent must have high heat resistance and high hydrothermal resistance, for example, a HC adsorbent used in a system for hydrocarbon adsorption or for purification of exhaust gas from internal combustion engine, such as an in-line type system for exhaust gas purification.
DISCLOSURE OF THE INVENTION
According to the present invention, there is provided an adsorbent comprising a &bgr;-silicate molecular sieve, which silicate contains at least Fe besides H, O and Si and, when Al is contained, contains Fe in a molar amount at least equal to that of Al.
Preferably, the &bgr;-silicate molecular sieve has a Si/Al molar ratio of 80 or more.
The adsorbent of the present invention is suitably used for adsorption of hydrocarbons and for purification of automobile exhaust gas.
REFERENCES:
patent: 3308069 (1967-03-01), Wadlinger et al.
patent: 4208305 (1980-06-01), Kouwenhoven et al.
patent: 4554145 (1985-11-01), Rubin
patent: 4568655 (1986-02-01), Oleck et al.
patent: 4585799 (1986-04-01), Morris et al.
patent: 4696732 (1987-09-01), Angevine et al.
patent: 4701313 (1987-10-01), Chang et al.
patent: 4827068 (1989-05-01), Chen et al.
patent: 5013537 (1991-05-01), Patarin et al.
patent: 5077026 (1991-12-01), Nair et al.
patent: 5110570 (1992-05-01), Bellussi et al.
patent: 5290533 (1994-03-01), Bellussi et al.
patent: 5312608 (1994-05-01), Hayasaka et al.
patent: 5409671 (1995-04-01), Takemoto et al.
patent: 5417947 (1995-05-01), Hertl et al.
patent: 5518976 (1996-05-01), Itoh et al.
patent: 5538697 (1996-07-01), Abe et al.
patent: 5558851 (1996-09-01), Miller
patent: 5648562 (1997-07-01), Henrick
patent: 5676912 (1997-10-01), Sharma et al.
patent: 5677254 (1997-10-01), Nojima et al.
patent: 5753121 (1998-05-01), Geus et al.
patent: 5863855 (1999-01-01), Nojima et al.
patent: 5925329 (1999-07-01), Williams et al.
patent: 6051205 (2000-04-01), Yamamoto et al.
patent: 0 064 328 A1 (1982-11-01), None
patent: 0 593 898 A1 (1994-04-01), None
patent: 5-220403 (1993-08-01), None
patent: 7-185326 (1995-07-01), None
patent: 8-10613 (1996-01-01), None
patent: 9-99207 (1997-04-01), None
Kumar R. et al.: “Convenient Synthesis of Crystalline Microporous Transition Metal Silicates Using Complexing Agents” Studies in Surface Science and Catalysis, vol. 84; Jul. 17, 1994; pp. 109-116, XP000619621 *the whole document*.
Patent Abstracts of Japan; vol. 097, No. 001; Jan. 31, 1997 & JP 08 229386 A (Mazda Motor Corp); Sep. 10, 1996 *abstract*.
Patent Abstracts of Japan; vol. 097, No. 005; May 30, 1997 & JP 09 000884 A (Babcock Hitachi KK); Jan. 7, 1997 *abstract*.
Database WPI; Section Ch, Week 9619; Derwent Publications Ltd., London, GB; Class E36, An 96-182793 XP00209518 & JP 08 057262 (Babcock Hitachi KK); Mar. 5, 1996 *abstract*.
Hiramatsu Takuya
Takahashi Akira
Yamamoto Azuma
Dunn Tom
NGK Insulators Ltd.
Nguyen Cam N.
LandOfFree
&bgr;-zeolite molecular sieve absorbent does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with &bgr;-zeolite molecular sieve absorbent, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and &bgr;-zeolite molecular sieve absorbent will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2488843