US4992405A
Expired / Lapsed
US
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Three-way catalyst for automotive emission control and method of making the catalyst
Assignee: University of Michigan (System)
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Filing: 1989-11-22
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Granted: 1991-02-12
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Expires: 2009-11-22
Abstract
Abstract A three-way catalyst construction, including its method of making, which deploys palladium and rhodium as precious metal catalysts, and lanthanum oxide and titania as a nonprecious metal catalyst, in a unique combination and in a unique manner. The three-way catalyst construction for automotive emission control, such catalyst being applied to a mechanical carrier having a support comprised substantially of alumina, comprises: (a) a discontinuous lanthanum oxide coating on the support; (b) a catalytic precious metal compound of palladium and rhodium, where rhodium is no greater than 10% by proportion of the palladium with palladium being at least 60% by weight of the precious metal catalyst, said precious metal catalyst being discontinuously supported on the decorated support; and (c) a nonprecious metal catalytic compound of titanium oxide disposed discontinuously on or about said precious metal catalyst compound and lanthana.
Inventors
- 👤 Mohinder S. Chattha
- 👤 William L. H. Watkins
- 👤 Haren S. Gandhi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 05:03
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9445; B01D53/945; B01J; B01J23/00; B01J23/38; B01J23/54; B01J23/56; B01J23/63; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
106 words
A three-way catalyst for automotive emissions, the catalyst being applied to a mechanical carrier having a support comprised substantially of alumina, comprising: (a) discontinuous lanthanum oxide on said support; (b) catalytic precious metal of palladium and rhodium with rhodium being present in an amount no greater than 10% by weight of the precious metal and palladium constituting at least 60% by weight of the precious metal, the catalytic precious metal being discontinuously supported on or about said support; and (c) titania discontinuously residing on or about said catalytic precious metal and lanthana, said titania being present in an amount of 0.1-8.0% by weight of said catalyst.
Claim 2
Dependent Claim
106 words
A three-way catalyst for automotive emissions, the catalyst being applied to a mechanical carrier having a support comprised substantially of alumina, comprising: (a) discontinuous lanthanum oxide on said support; (b) catalytic precious metal of palladium and rhodium with rhodium being present in an amount no greater than 10% by weight of the precious metal and palladium constituting at least 60% by weight of the precious metal, the catalytic precious metal being discontinuously supported on or about said support; and (c) titania discontinuously residing on or about said catalytic precious metal and lanthana, said titania being present in an amount of 0.1-8.0% by weight of said catalyst.
Claim 3
Dependent Claim
99 words
A three-way catalyst for automotive emission control having a support comprised substantially of alumina, comprising: (a) discontinuous lanthanum oxide decoration on said support; (b) palladium supported discontinuously on the decorated support, said palladium being present in an amount of 0.05-5.0% by weight of the catalyst; (c) a discontinuous phase of titanium oxide superimposed on said palladium/lanthana decorated support, said titanium dioxide being present in an amount of 0.1-8.0% by weight of said catalyst; and (d) rhodium supported discontinuously on said titania/palladium/lanthana decorated support, said rhodium being present in an amount no greater than 10% by weight of said palladium.
Claim 4
Dependent Claim
99 words
A three-way catalyst for automotive emission control having a support comprised substantially of alumina, comprising: (a) discontinuous lanthanum oxide decoration on said support; (b) palladium supported discontinuously on the decorated support, said palladium being present in an amount of 0.05-5.0% by weight of the catalyst; (c) a discontinuous phase of titanium oxide superimposed on said palladium/lanthana decorated support, said titanium dioxide being present in an amount of 0.1-8.0% by weight of said catalyst; and (d) rhodium supported discontinuously on said titania/palladium/lanthana decorated support, said rhodium being present in an amount no greater than 10% by weight of said palladium.
Claim 5
Dependent Claim
32 words
The catalyst as in claim 2, characterized by a conversion efficiency of NO at 100° C. of at least 70% and a hydrocarbon conversion efficiency at 350° C. of at least 70%.
Claim 6
Dependent Claim
21 words
The catalyst as in claim 2, in which said discontinuous titania phase is 0.1-2.0% of the total weight of the catalyst.
Claim 7
Dependent Claim
22 words
The catalyst as in claim 1, in which said rhodium is present in the range of 0.08-1.5% by weight of the catalyst.
Claim 8
Dependent Claim
22 words
The catalyst as in claim 1, in which said titania is present in the range of 0.1-2.0% by weight of the catalyst.
Claim 9
Dependent Claim
22 words
The catalyst as in claim 1, in which said lanthana is present in an amount of 30% by weight of the catalyst.
Claim 10
Dependent Claim
36 words
The catalyst as in claim 1, characterized by a conversion efficiency of NO at lambda of 1.1 or greater of at least 94% and an HC conversion efficiency at lambda of 1.4 of at least 60%.
Claim 11
Dependent Claim
20 words
The catalyst as in claim 1, characterized by production of ammonia at lambda of 1.6 of no greater than 3%.
Claim 12
Independent Claim
104 words
A method of making a three-way catalyst for automotive emissions control, comprising: (a) discontinuously coating lanthana on an alumina support; (b) impregnating the lanthana support with a palladium compound to form a discontinuous phase on the lanthana and support; (c) impregnating the palladium/lanthana support with an organo-titanium compound to form, upon heating, a discontinuous titanium oxide phase on the exposed portions of the discontinuous palladium/lanthana/alumina particles, said compound being used in an amount of 0.1-8.0% by weight of the total catalyst; and (d) impregnating the product of step (c) with rhodium in an amount no greater than 0.15% of the weight of the catalyst.
Claim 13
Independent Claim
104 words
A method of making a three-way catalyst for automotive emissions control, comprising: (a) discontinuously coating lanthana on an alumina support; (b) impregnating the lanthana support with a palladium compound to form a discontinuous phase on the lanthana and support; (c) impregnating the palladium/lanthana support with an organo-titanium compound to form, upon heating, a discontinuous titanium oxide phase on the exposed portions of the discontinuous palladium/lanthana/alumina particles, said compound being used in an amount of 0.1-8.0% by weight of the total catalyst; and (d) impregnating the product of step (c) with rhodium in an amount no greater than 0.15% of the weight of the catalyst.
Claim 14
Dependent Claim
59 words
The method as in claim 10, in which palladium is impregnated by use of a diluted palladium nitrate solution with the amount of acid in such solution being regulated to a pH of 3-5 to provide incipient wetness, and after drying the wetted support with said acid, calcining the composite at a temperature in the range of 450°-650° C.
Claim 15
Dependent Claim
34 words
The method as in claim 10, in which the organo-titanium compound is dissolved in a liquid for wetting said composite, said wetted composite being calcined at a temperature of 400°-600° C. for 4-12 hours.
Claim 16
Dependent Claim
32 words
The method as in claim 12, in which said calcination is staged to include heating to 250°-280° C. for 11/2 to 21/2 hours, and thence heating to 400°-600° C. for 5-10 hours.
Claim 17
Dependent Claim
14 words
The method as in claim 10, in which said organo-titanium compound is titanium butoxide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-11 | 1994-08-13 | 1995-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-11 | 1998-08-13 | 1999-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-11 | 2002-08-13 | 2003-02-12 | $7700.00 | Window Closed / Lapsed |