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EP0541271A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Catalyst system for treating the exhaust from a lean-burn gasoline-fueled engine

Assignee: Ford-Werke GmbH
•
Filing: 1992-10-22
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Granted: —
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Expires: 2012-10-22
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Abstract

Abstract A catalyst system for converting NO x , CO, and HC contained in the exhaust gas from a gasoline-fueled engine controlled to operate under lean-burn conditions (R = .03-.9) such that the a ratio of NO x to HC in the exhaust gas is in the range of 1/3 to 3/1 (i.e., minimum C₃H₆ of 250 ppm and NO x of 200-400 ppm). The system comprises a first stage catalyst containing a transition metal-exchanged zeolite (i.e., Cu-ZSM5), and a three-way catalyst for treating the effluent from said first stage catalyst. The second stage catalyst consists of a high surface area alumina support impregnated with an intimate mixture of .5-20% lanthana, .2-30% palladium, and advantageously an outer washcoat TiO₂. A method of treating the exhaust gas from a fossil-fueled engine comprising operating the engine under lean-burn conditions while controlling the emission ratio of NO x /hydrocarbon to be in the range of 1/3 to 3/1; exposing the exhaust gas to a first stage catalyst comprising a copper ion-exchanged ZSM5 zeolite having at least 3% by weight copper; and exposing the effluent from said first stage catalyst to a second stage catalyst comprising an alumina support impregnated with an intimate mixture of .5-20% lanthana and 2-30% palladium.

Inventors

  • 👤 Somasundaram Subramanian
  • 👤 Mohinder S. Chattha

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-29 22:30
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; B01J35/00; B01J35/19; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 91 words
A catalyst system for converting NO x , CO, and HC contained in the exhaust gas from a gasoline-fueled engine controlled to operate under lean-burn conditions such that the ratio of NO x to HC in the exhaust is in the range of 1/3 to 3/1, the system comprising: (a) a first stage catalyst comprising a transition metal-containing zeolite; and (b) a three-way catalyst for treating the effluent from said first stage catalyst comprising a high surface area alumina support impregnated with an intimate mixture of .5-20% lanthana and .2-30% palladium.
Claim 2
Dependent Claim 29 words
A catalyst system as claimed in claim 1, in which said lanthana and palladium reside discontinuously on said support so that each may be exposed to the exhaust gas.
Claim 3
Dependent Claim 37 words
A catalyst system as claimed in claim 1, in which said second stage catalyst additionally comprises an outer washcoat consisting of titanium oxide, said additional element being useful when exhaust has a redox ratio of 0.8-0.9 R.
Claim 4
Dependent Claim 32 words
A catalyst system as claimed in claim 1, in which said second stage catalyst additionally comprises a stabilizing washcoat on said support selected from oxides of nickel, cerium, barium, lanthanum, and titanium.
Claim 5
Dependent Claim 22 words
A catalyst system as claimed in claim 4, in which said stabilizing washcoat has a thickness in the range of 0.005-0.1 mm.
Claim 6
Dependent Claim 26 words
A catalyst system as claimed in claim 1, in which said alumina is predominantly gamma alumina having a surface area in the range of 50-400 m²/g.
Claim 7
Independent Claim 89 words
A method of treating the exhaust gas from a fossil-fueled engine, comprising: (a) operating the engine under lean-burn conditions while controlling the emission ratio of NO x /hydrocarbon to be in the range 1/3 to 3/1; (b) exposing such exhaust gas to a first stage catalyst comprising a copper ion-exchanged ZSM5 zeolite having at least 3% by weight copper; and (c) exposing the effluent from said first stage catalyst to a second stage catalyst comprising an alumina support impregnated with an intimate mixture of .5-20% lanthana and 2-30% palladium.
Claim 8
Dependent Claim 55 words
A method as claimed in claim 7, in which said first and second stage catalysts are effective to provide a NO x conversion efficiency of 38-50% when the exhaust gas NO x content is 400-1300 ppm and a NO x conversion efficiency of 50-80% when the exhaust gas NO x content is about 200-400 ppm.

References Cited (Backward Citations)

EP0430437A2 Cited
EP0460507A1 Cited

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