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EP0617199B1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Catalytic converter for reducing nitrogen oxide content in exhaust gases of an internal combustion engine

Assignee: Siemens AG
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Filing: 1994-03-14
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Granted: 1996-01-31
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Expires: 2014-03-14
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Abstract

Abstract In the denitrification of exhaust gas from internal combustion engines, in particular from diesel engines, there is always the problem, if the process of selective catalytic reduction is used, that it is desired to set high degrees of separation for the nitrogen oxides and only a very low ammonia slip on the catalyst for all load states of the internal combustion engine. For this purpose, the invention provides a catalyst (8) which comprises a catalyst support (26,28) and a catalytically active layer (34) and in which the storable quantity of reducing agent, in most cases ammonia, increases per unit length in the direction of flow of the exhaust gas (30). The result of this is that the catalyst (8), with respect to its response behaviour and its capacity for storing ammonia, rapidly follows, alternating operating states of the internal combustion engine along its flow path without significant slip of ammonia and nitrogen oxides. The invention can be used in principle in all internal combustion engines which run with excess air. <IMAGE>

Inventors

  • 👤 Helmut Dr. Schmelz

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-30 22:28
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; F01N3/2066; B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9418; B01D53/9431; F01N13/00; F01N13/009; F01N13/0097; F01N3/24; F01N3/28; F01N3/2803; F01N3/2807; F01N3/281; F01N3/2825; F01N3/2828; B01D2251/00; B01D2251/20; B01D2251/206; B01D2251/2067; B01D2255/00; B01D2255/20; B01D2255/207; B01D2255/20707; B01D2255/20723; B01D2255/20769; B01D2255/20776; B01D2255/90; B01D2255/911; B01D2258/00; B01D2258/01; B01D2258/012; F01N2570/00; F01N2570/14; F01N2610/00; F01N2610/02; F02; F02B; F02B3/00; F02B3/06; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 90 words
Catalytic converter (8) for reducing nitrogen oxide in the exhaust gas (30) of an internal combustion engine, in particular a diesel engine, in the presence of a reducing agent (18), having a catalyst carrier (26, 28) and a catalytically active layer (34), wherein the quantity of reducing agent (18), which can be stored per unit of length, increases in the direction of flow of the exhaust gas (30), characterised in that the thickness of the catalytically active layer (34) increases in the direction of flow of the exhaust gas (30).
Claim 2
Dependent Claim 29 words
Catalytic converter according to claim 1, characterised in that the thickness of the catalytically active layer (34) at the gas inlet has substantially the thickness of the reaction zone.
Claim 3
Dependent Claim 33 words
Catalytic converter according to claim 1 or 2, characterised in that the thickness of the catalytically active layer (34) at the gas outlet is a multiple of the thickness of the reaction zone.
Claim 4
Dependent Claim 27 words
Catalytic converter according to one of the claims 1 to 3, characterised in that the catalytically active layer (34) is applied to a metal carrier (26, 28).
Claim 5
Dependent Claim 25 words
Catalytic converter according to one of the claims 1 to 4, characterised in that the catalytically active layer (34) is applied to a ceramic carrier.
Claim 6
Dependent Claim 37 words
Catalytic converter according to one of the claims 1 to 4, characterised in that a fully ceramic honeycomb is provided, the wall thickness of which honeycomb increases in the direction of flow of the exhaust gas (30).
Claim 7
Dependent Claim 65 words
Catalytic converter according to one of the claims 1 to 6, characterised in that arranged in the direction of flow of the exhaust gas (30) in the first instance there is a partial catalytic converter (22) having a metallic carrier (26, 28) and catalytically active layer (34) applied thereto and following this there is a further partial catalytic converter (24) having a fully ceramic honeycomb.
Claim 8
Dependent Claim 26 words
Catalytic converter according to one of the claims 1 to 7, characterised in that means for generating turbulent flows of the exhaust gas (30) are provided.
Claim 9
Dependent Claim 41 words
Catalytic converter according to one of the claims 1 to 8, characterised in that arranged in the direction of flow of the exhaust gas (30) finally there is a partial catalytic converter which is formed as an oxidation catalytic converter (10).
Claim 10
Dependent Claim 39 words
Catalytic converter according to one of the claims 1 to 9, characterised in that the catalytically active layer includes titanium dioxide (TiO₂) and one or more of the additives tungsten oxide (WO₂), molybdenum oxide (MoO) and vanadium oxide (VO).
Claim 11
Dependent Claim 45 words
Catalytic converter according to one of the claims 1 to 10, characterised in that the catalytically active layer includes a phase with the summation formula V x Mo y O 32-z with x + y ≤ 12; x, y ≥ 1 and z ≤ 1.

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