US6334986B2
Expired / Lapsed
US
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Process for the selective catalytic reduction of the nitrogen oxides contained in a lean exhaust gas
Assignee: DMC2 Degussa Metals Catalysts Cerdec AG
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Filing: 2001-01-11
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Granted: 2002-01-01
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Expires: 2021-01-11
Abstract
Abstract The invention relates to a process for the selective catalytic reduction of the nitrogen oxides contained in a lean exhaust gas from internal combustion engines by reducing the nitrogen oxides by means of ammonia on a catalyst. The process is characterized in that, in addition to the lean exhaust gas, a rich gas stream is produced that is treated in an electrical gas discharge plasma in order to form the ammonia required for the reduction.
Inventors
- 👤 Jürgen Gieshoff
- 👤 Hans Van Den Tillaart
- 👤 Thomas Kreuzer
- 👤 Egbert Lox
- 👤 Jürgen Lang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:40
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; F01N3/2066; F01N3/2073; B; B01; B01D; B01D53/00; B01D53/32; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9418; B01D53/9431; F01N13/00; F01N13/009; B01D2251/00; B01D2251/20; B01D2251/206; B01D2251/2062; B01D2255/00; B01D2255/10; B01D2255/102; B01D2255/1021; B01D2255/1023; B01D2255/1025; B01D2255/1028; B01D2255/20; B01D2255/204; B01D2255/2042; B01D2255/206; B01D2255/2065; B01D2255/207; B01D2255/20738; B01D2255/20761; B01D2255/50; F01N2240/00; F01N2240/25; F01N2240/28; F01N2610/00; F01N2610/02; Y; Y02; Y02C; Y02C20/00; Y02C20/10; Y02T; Y02T10/00; Y02T10/10; Y02T10/12; Y10; Y10S; Y10S423/00; Y10S423/09; Y10S423/10
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
100 words
A process for the selective catalytic reduction of nitrogen oxides contained in a lean exhaust gas from an internal combustion engine with one or more cylinders, comprising: a) producing a rich gas stream with a normalized air/fuel-ratio of less than 1, b) forming ammonia in the rich gas stream by treating the rich exhaust gas stream in an electrical gas discharge plasma generated between two electrodes, c) combining the lean exhaust gas with the rich gas stream, and d) reducing the nitrogen oxides contained in the lean exhaust gas on a reduction catalyst using the ammonia as a reducing agent.
Claim 2
Dependent Claim
100 words
A process for the selective catalytic reduction of nitrogen oxides contained in a lean exhaust gas from an internal combustion engine with one or more cylinders, comprising: a) producing a rich gas stream with a normalized air/fuel-ratio of less than 1, b) forming ammonia in the rich gas stream by treating the rich exhaust gas stream in an electrical gas discharge plasma generated between two electrodes, c) combining the lean exhaust gas with the rich gas stream, and d) reducing the nitrogen oxides contained in the lean exhaust gas on a reduction catalyst using the ammonia as a reducing agent.
Claim 3
Dependent Claim
19 words
The process according to claim 1 , wherein the rich gas stream is produced by a sub-stoichiometrically operating burner.
Claim 4
Dependent Claim
39 words
The process according to claim 1 , wherein the rich gas stream forms part of the exhaust gas stream from the internal combustion engine and is obtained by operating one cylinder of the engine with a sub-stoichiometric air/fuel mixture.
Claim 5
Dependent Claim
21 words
The process according to claim 1 , wherein the rich gas stream is formed by injecting hydrocarbons into an air stream.
Claim 6
Dependent Claim
48 words
The process according to claim 1 , wherein the reduction catalyst contains the following components: a) titanium dioxide; b) at least one oxide of tungsten, silicon, boron, aluminum, phosphorus, zirconium, barium, yttrium, lanthanum and cerium, and c) at least one oxide of vanadium, niobium, molybdenum, iron and copper.
Claim 7
Dependent Claim
27 words
The process according to claim 1 , wherein the reduction catalyst comprises a zeolite catalyst that contains copper, iron, cerium or mixtures thereof on a mordenite zeolite.
Claim 8
Dependent Claim
37 words
The process according to claim 1 , wherein a dielectrically hindered discharge at atmospheric pressure with a product (d*p) of the electrode interspacing and pressure of between 0.05 and 100 mm*bar is used as the gas discharge.
Claim 9
Dependent Claim
47 words
The process according to claim 7 , further comprising generating the discharge in the annular space between two tubular electrodes arranged concentrically with respect to one another, at least one of which is coated with a dielectric on the mutually opposite jacket surfaces of the tubular electrodes.
Claim 10
Dependent Claim
71 words
The process according to claim 7 , further comprising: exciting the discharge in the flow channels of a honeycomb body obtained by stacking alternately smooth and corrugated metal sheets on top of one another, wherein either the smooth or corrugated sheets or both types of sheets are coated with a dielectric to achieve electrical insulation from one another, wherein a discharge voltage is applied between all smooth and all corrugated sheets.
Claim 11
Dependent Claim
26 words
The process according to claim 9 , wherein the discharge is excited with a pulsed voltage having a frequency of between 50 Hz and 250 kHz.
Claim 12
Dependent Claim
30 words
The process according to claim 9 , wherein the discharge is excited with an alternating voltage between 0.2 and 15 kV and a frequency between 50 Hz and 250 kHz.
Claim 13
Dependent Claim
16 words
The process according to claim 9 , wherein the electrodes have surfaces which are structured three-dimensional.
Claim 14
Dependent Claim
23 words
The process according to claim 9 , wherein the dielectric comprises a catalyst coating of finely divided support materials and catalytically active components.
Claim 15
Dependent Claim
32 words
The process according to claim 9 , wherein a catalyst layer of finely divided support materials and catalytically active components is applied to the coating of the metal sheets with the dielectric.
Claim 16
Dependent Claim
33 words
The process according to claim 14 , wherein aluminium oxide, titanium oxide, zirconium oxide, cerium oxide, silicon dioxide, magnesium oxide or their mixed oxides and zeolites are used as finely divided support materials.
Claim 17
Dependent Claim
22 words
The process according to claim 15 , wherein the finely divided support materials are stabilized with silicon dioxide and/or rare earth oxides.
Claim 18
Dependent Claim
30 words
The process according to claim 15 , wherein the catalyst coating contains at least one of the catalytically active components platinum, palladium, rhodium and iridium in a highly dispersed form.
Claim 19
Dependent Claim
32 words
The process according to claim 15 , wherein the catalyst coating additionally contains at least one basic oxide of the alkali or alkaline earth metals of the periodic system of the elements.
Claim 20
Dependent Claim
32 words
The process according to claim 7 , wherein the discharge is generated between two parallel plate electrodes, at least one of which is coated on the mutually opposite faces with a dielectric.
Claim 21
Dependent Claim
25 words
The process according to claim 19 , wherein a catalyst layer of finely particulate support materials and catalytically active components is applied to the dielectric.
Claim 22
Dependent Claim
23 words
The process according to claim 19 , wherein the dielectric comprises a catalyst coating of finely particulate support materials and catalytically active components.
Claim 23
Dependent Claim
25 words
The process according to claim 21 , wherein the alternating voltage is operated in a pulsed manner with a frequency between 0.01 and 10 Hz.
Claim 24
Dependent Claim
19 words
The process according to claim 19 , wherein the discharge space between the electrodes is filled with ceramic pellets.
Claim 25
Dependent Claim
42 words
The process according to claim 23 , wherein the ceramic pellets comprise at least one finely divided support material selected from the group consisting of aluminum oxide, titanium oxide, zirconium oxide, cerium oxide, silicon dioxide, magnesium oxide, mixed oxides thereof and zeolites.
Claim 26
Dependent Claim
22 words
The process according to claim 24 , wherein the finely divided support materials are stabilized with silicon dioxide and/or rare earth oxides.
Claim 27
Dependent Claim
30 words
The process according to claim 24 , wherein the ceramic pellets contain at least one of the catalytically active components platinum, palladium, rhodium and iridium in a highly dispersed form.
Claim 28
Dependent Claim
32 words
The process according to claim 24 , wherein the ceramic pellets additionally contain at least one basic oxide of the alkali or alkaline earth metals of the periodic system of the elements.
References Cited (Backward Citations)
JPS5860614A
Cited
EP0376025B1
Cited
EP0385164B1
Cited
DE19510804A1
Cited
EP0861972A1
Cited
EP0814241A1
Cited
US5711147A
Cited
US6176078B1
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2004-12-31 | 2005-07-02 | 2006-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-12-31 | 2009-07-02 | 2010-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-12-31 | 2013-07-02 | 2014-01-01 | $7700.00 | Window Closed / Lapsed |