Patent EP0427494A2 successfully refreshed from Google Patents.
EP0427494A2
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EP
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Staged three-way conversion catalyst and method for using the same
Assignee: BASF Catalysts LLC
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Filing: 1990-11-05
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Granted: —
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Expires: 2010-11-05
Abstract
Abstract A catalyst composition has an upstream stage and a downstream stage, the upstream stage containing a catalytic material which is different from the catalytic material contained on the downstream stage and is characterized by having a low ignition temperature, e.g., 350°C to less than 400°C, for the substantially simultaneous conversion of HC, CO and NO x pollutants contained in, e.g., the exhaust of an automobile engine operating at a substantially stoichiometric air-to-fuel weight ratio. The downstream catalytic material is characterized by having a higher conversion efficiency for substantially simultaneous conversion of HC, CO and NO x than the upstream catalytic material at elevated operation temperatures which may be, for example, from about 400 to 800°C. The method of the invention includes passing a gaseous exhaust stream containing HC, CO and NO x pollutants sequentially through first the upstream and then through the downstream catalytic materials.
Inventors
- 👤 Wayne M. Rudy
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 21:23
CPC Classifications
B; B01; B01J; B01J23/00; B01J23/38; B01J23/54; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9445; B01D53/945; B01J23/56; B01J23/63; B01J35/00; B01J35/19; B01J37/00; B01J37/02; B01J37/024; B01J37/0244; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
122 words
A catalyst composition for converting HC, CO and NO x in a gaseous stream flowed therethrough, the composition comprising an upstream catalyst member and a downstream catalyst member, as sensed in the direction of flow of the gaseous stream through the catalyst composition, wherein: (a) the upstream catalyst member comprises a first catalytic material characterized by having an ignition temperature for substantially simultaneous conversion of HC, CO and NO x which is lower than that of a second catalytic material, defined below; and (b) the downstream catalyst member comprises a second catalytic material characterized by having a higher conversion efficiency than the first catalytic material for substantially simultaneous conversion of HC, CO and NO x at operating temperatures above the ignition temperature.
Claim 2
Dependent Claim
122 words
A catalyst composition for converting HC, CO and NO x in a gaseous stream flowed therethrough, the composition comprising an upstream catalyst member and a downstream catalyst member, as sensed in the direction of flow of the gaseous stream through the catalyst composition, wherein: (a) the upstream catalyst member comprises a first catalytic material characterized by having an ignition temperature for substantially simultaneous conversion of HC, CO and NO x which is lower than that of a second catalytic material, defined below; and (b) the downstream catalyst member comprises a second catalytic material characterized by having a higher conversion efficiency than the first catalytic material for substantially simultaneous conversion of HC, CO and NO x at operating temperatures above the ignition temperature.
Claim 3
Dependent Claim
85 words
The catalyst composition of claim 1 wherein the first catalytic material has, when the gaseous stream is a substantially stoichiometric exhaust gas mixture, an ignition temperature for substantially simultaneous conversion of HC, CO and NO x which is less than about 400°C, and the downstream catalyst member has, for the gaseous stream treated by the upsream catalyst member, a conversion efficiency of at least about 94% for substantially simultaneous converson of HC, CO and NO x at an operation temperature of at least about 400°C.
Claim 4
Dependent Claim
16 words
The catalyst composition of claim 2 wherein the ignition temperature is not more than about 350°C.
Claim 5
Dependent Claim
20 words
The catalyst composition of claim 2 or claim 3 wherein the operating temperature range is from about 400 to 800°C.
Claim 6
Dependent Claim
16 words
The catalyst composition of claim 4 wherein the ignition temperature is not more than about 375°C.
Claim 7
Dependent Claim
69 words
The catalyst composition of claim 1, claim 2 or claim 3 wherein (a) the first catalytic material comprises a platinum catalytic component dispersed on a refractory metal oxide support and a rhodium catalytic component dispersed on a refractory metal oxide support, and (b) the second catalytic material comprises a rhodium catalytic component disposed on a zirconia/dispersed ceria support and platinum catalytic component disposed on a refractory metal oxide support.
Claim 8
Dependent Claim
106 words
The catalyst composition of claim 1, claim 2 or claim 3 wherein (a) the first catalytic material comprises a first platinum catalytic component dispersed on a first activated alumina support, a rhodium catalytic component dispersed on a second activated alumina support, and a second platinum catalytic component disposed on a ceria support, and (b) the second catalytic material comprises a second rhodium catalytic component dispersed on a zirconia/dispersed ceria support, a third rhodium catalytic component disposed on a third activated alumina support, a third platinum catalytic component disposed on a a fourth activated alumina support, and a fourth platinum catalytic component disposed on a ceria support.
Claim 9
Dependent Claim
49 words
The catalyst composition of claim 7 further including in one or both of the first and second catalyst materials a minor amount of a high-porosity refractory metal oxide which is substantially free of catalytic metal components and increases the porosity of the catalytic material in which it is included.
Claim 10
Dependent Claim
20 words
The catalyst composition of claim 7 wherein botj=h the first and second catalytic materials are disposed on a carrier substrate.
Claim 11
Dependent Claim
28 words
The catalyst composition of claim 9 wherein at least one of the first and second catalytic materials comprises a topcoat overlying an undercoat comprising a stabilized alumina support.
Claim 12
Dependent Claim
20 words
The catalyst composition of claim 1 or claim 2 comprising a discrete upstream catalyst member and discrete downstream catalyst member.
Claim 13
Dependent Claim
26 words
The catalyst composition of claim 11 wherein the upstream and downstream catalyst members are spaced one from the other and separated by a gas flow zone.
Claim 14
Independent Claim
253 words
A method of substantially simultaneously converting HC, CO and NO x pollutants contained in a gaseous stream, the method comprising: (a) flowing the gaseous stream through a first catalyst zone and therein contacting the gaseous stream with a first catalyst member comprising a first catalytic material having an ignition temperature for substantially simultaneous conversion of HC, CO and NO x , when the gaseous stream is a substantially stoichiometric exhaust gas mixture, which is lower than the corresponding ignition temperature of a second catalytic material, defined below, the gaseous stream being introduced into the first catalyst zone at a temperature at or above the ignition temperature of the first catalytic material but below an operating temperature range, defined below, to convert within said first catalyst zone some, but less than all, of each of the HC, CO and NO x content of the gaseous stream to innocuous substances and thereby increase the temperature of the gaseous stream, and (b) flowing the gaseous stream from the first catalyst zone to a second catalyst zone and therein contacting the gaseous stream with a second catalyst member comprising a second catalytic material having a higher conversion efficiency for substantially simultaneous conversion of HC, CO and NO x at temperatures within the operating temperature range than does the first catalytic material, the gaseous stream being contacted with the second catalytic material at a temperature within the operating temperature range to substantially simultaneously convert at least some of the remaining HC, CO and NO x to innocuous substances.
Claim 15
Independent Claim
253 words
A method of substantially simultaneously converting HC, CO and NO x pollutants contained in a gaseous stream, the method comprising: (a) flowing the gaseous stream through a first catalyst zone and therein contacting the gaseous stream with a first catalyst member comprising a first catalytic material having an ignition temperature for substantially simultaneous conversion of HC, CO and NO x , when the gaseous stream is a substantially stoichiometric exhaust gas mixture, which is lower than the corresponding ignition temperature of a second catalytic material, defined below, the gaseous stream being introduced into the first catalyst zone at a temperature at or above the ignition temperature of the first catalytic material but below an operating temperature range, defined below, to convert within said first catalyst zone some, but less than all, of each of the HC, CO and NO x content of the gaseous stream to innocuous substances and thereby increase the temperature of the gaseous stream, and (b) flowing the gaseous stream from the first catalyst zone to a second catalyst zone and therein contacting the gaseous stream with a second catalyst member comprising a second catalytic material having a higher conversion efficiency for substantially simultaneous conversion of HC, CO and NO x at temperatures within the operating temperature range than does the first catalytic material, the gaseous stream being contacted with the second catalytic material at a temperature within the operating temperature range to substantially simultaneously convert at least some of the remaining HC, CO and NO x to innocuous substances.
Claim 16
Dependent Claim
40 words
The method of claim 13 wherein the ignition temperature of the first catalytic material is less than about 400°C and contacting the gaseous stream with the second catalyst member within an operating temperature range of from about 400°C to 800°C.
Claim 17
Dependent Claim
15 words
The method of claim 14 wherein the ignition temperature is not more than about 350°C.
Claim 18
Dependent Claim
69 words
The method of claim 13, claim 14 or claim 15 wherein (a) the first catalytic material comprises a platinum catalytic component dispersed on a refractory metal oxide support and a rhodium catalytic component dispersed on a refractory metal oxide support, and (b) the second catalytic material comprises a rhodium catalytic component disposed on a zirconia/dispersed ceria support and a platinum catalytic component disposed on a refractory metal oxide support.
Claim 19
Dependent Claim
106 words
The method of claim 13, claim 14 or claim 15 wherein (a) the first catalytic material comprises a first platinum catalytic component dispersed on a first activated alumina support, a rhodium catalytic component dispersed on a second activated alumina support, and a second platinum catalytic component dispersed on a ceria support, and (b) the second catalytic material comprises a second rhodium catalytic component dispersed on a zirconia/dispersed ceria support, a third rhodium catalytic component disposed on a third activated alumina support, a third platinum catalytic component disposed on a a fourth activated alumina support, and a fourth platinum catalytic component disposed on a cer ia support.
Claim 20
Dependent Claim
50 words
The method of claim 17 wherein there is included in one or both of the first and second catalyst materials a minor amount of a high-porosity refractory metal oxide which is substantially free of catalytic metal components and increases the porosity of the catalytic material in which it is included.
References Cited (Backward Citations)
US3896616A
Cited
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