EP0283913A2
Expired / Lapsed
EP
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Process for removal of NOx from fluid streams
Assignee: WR Grace and Co Conn
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Filing: 1988-03-16
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Granted: —
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Expires: 2008-03-16
Abstract
Abstract There is provided a process and apparatus for carrying out the process, to remove nitrogen oxides from a gas stream. The process is characterized by passing the gas stream through a first catalytic zone in the absence of added ammonia and in the presence of an oxidation catalyst to convert the NO content thereof to NO₂, thereafter introducing ammonia into the gas stream, and catalytically reducing the NO₂ to nitrogen and water in the presence of a catalyst. Higher conversion to innocuous materials is obtained.
Inventors
- 👤 William R. Alcorn
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 21:54
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/38; F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; F01N3/2066; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; F01N13/00; F01N13/009; F01N13/0097; F01N3/24; F01N3/28; F01N3/2839; F01N3/2853; F01N2610/00; F01N2610/02; F01N2610/14; F01N2610/1453; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
69 words
A process for removing nitrogen oxides from a gas stream containing free oxygen and converting them to nitrogen and water which comprises the steps of contacting said gas stream with an oxidation catalyst in a first zone in the substantial absence of added ammonia, adding ammonia to said gas as it leaves said first zone, and thereafter contacting said gas stream with a reduction catalyst in a second zone.
Claim 2
Dependent Claim
69 words
A process for removing nitrogen oxides from a gas stream containing free oxygen and converting them to nitrogen and water which comprises the steps of contacting said gas stream with an oxidation catalyst in a first zone in the substantial absence of added ammonia, adding ammonia to said gas as it leaves said first zone, and thereafter contacting said gas stream with a reduction catalyst in a second zone.
Claim 3
Dependent Claim
20 words
A process as defined in Claim 1 wherein the gas temperature in said first zone is at least about 100°C.
Claim 4
Dependent Claim
21 words
A process as defined in Claim 1 wherein the gas temperature in said first zone is from 100°C. to about 400°C.
Claim 5
Dependent Claim
20 words
A process as defined in Claim 1 wherein the gas temperature in said second zone is at least about 175°C.
Claim 6
Dependent Claim
21 words
A process as defined in Claim 1 wherein the gas temperature in said second zone is about 175°C. to about 400°C.
Claim 7
Dependent Claim
35 words
A process as defined in Claim 1 wherein the gas temperature in said first zone is from about 100°C. to 400°C. and the temperature in said second zone is from about 175°C. to about 400°C.
Claim 8
Dependent Claim
13 words
A process as defined in Claim 1 wherein the oxidation catalyst is platinum.
Claim 9
Dependent Claim
18 words
A process as defined in Claim 1 wherein the oxidation catalyst is a mixture of platinum and rhodium.
Claim 10
Dependent Claim
13 words
A process as defined in Claim 1 wherein the oxidation catalyst is palladium.
Claim 11
Dependent Claim
18 words
A process as defined in Claim 1 wherein the oxidation catalyst is a mixture of palladium and rhodium.
Claim 12
Dependent Claim
16 words
A process defined in Claim 1 wherein the reduction catalyst is a metal or metal oxide.
Claim 13
Dependent Claim
29 words
A process as defined in Claim 11 wherein the metal or metal oxide is or includes a metal selected from Group IV or Group V of the Periodic Table.
Claim 14
Dependent Claim
14 words
A process as defined in Claim 12 wherein the metal oxide is titanium dioxide.
Claim 15
Dependent Claim
14 words
A process as defined in Claim 12 wherein the metal oxide is vanadium pentoxide.
Claim 16
Dependent Claim
21 words
A process as defined in Claim 11 wherein the metal oxide is a mixture of at least two base metal oxides.
Claim 17
Dependent Claim
17 words
A process as defined in Claim 11 wherein the metal or metal oxide is a noble metal.
Claim 18
Dependent Claim
26 words
A process as defined in Claim 15 wherein the mixture of at least two base metal oxides is a mixture of vanadium pentoxide and titanium dioxide.
Claim 19
Dependent Claim
24 words
A process as defined in Claim 17 in which the metal ratio of the vanadium to the titanium is about 1:5 to about 1:30.
Claim 20
Dependent Claim
25 words
A process as defined in Claim 15 wherein the mixture of at least two metal oxides is a mixture of ceria, alumina, vanadia and titania.
Claim 21
Dependent Claim
14 words
A process as defined in Claim 18 in which the metal ratio is 1:19.
Claim 22
Dependent Claim
39 words
A process as defined in Claim 1 in which the ratio of the space velocity of the gas in the first zone to the space velocity of the gas in the second zone is from about 5:1 to 1:5.
Claim 23
Dependent Claim
14 words
A process as defined in Claim 21 in which the ratio is about 2:1.
Claim 24
Dependent Claim
33 words
A process as defined in Claim 1 in which the space velocity of the gas passing through the first zone is in the range of from about 10,000 hr⁻¹ to about 60,000 hr⁻¹.
Claim 25
Dependent Claim
33 words
A process as defined in Claim 1 in which the space velocity of the gas passing through the second zone is in the range of from about 5000 hr⁻¹ to about 20,000 hr⁻¹.
Claim 26
Dependent Claim
32 words
A process as defined in Claim 1 in which the first zone is about 20,000 hr⁻¹ and the space velocity of the gas passing through the second zone is about 10,000 hr⁻¹.
Claim 27
Dependent Claim
24 words
A process as defined in Claim 1 in which the molar ratio of added ammonia to nitrogen oxides collectively is about 0.7:1 to 1.3:1.
Claim 28
Dependent Claim
20 words
A process as defined in Claim 1 in which the oxidation catalyst is in the form of a fixed bed.
Claim 29
Dependent Claim
17 words
A process as defined in Claim 1 in which the oxidation catalyst is supported on porous alumina.
Claim 30
Dependent Claim
20 words
A process as defined in Claim 1 in which the reducing catalyst is in the form of a fixed bed.
Claim 31
Dependent Claim
17 words
A process as defined in Claim 1 in which the reducing catalyst is supported on porous alumina.
Claim 32
Dependent Claim
20 words
A process as defined in Claim 28 in which th porous alumina is supported in turn on a metal substrate.
Claim 33
Dependent Claim
20 words
A process as defined in Claim 30 in which the porous alumina is supported in turn on a metal substrate.
Claim 34
Dependent Claim
31 words
A process as defined in Claim 1 in which each of the zones is subdivided into a plurality of cells and the catalyst is supported on the walls of said cells.
Claim 35
Dependent Claim
29 words
A process as defined in Claim 33 in which the density of the cells is in the range of from about 100 to about 400 cells per square inch.
Claim 36
Independent Claim
162 words
An apparatus for removing nitrogen oxides from a gas stream and converting such oxides to nitrogen and water, which apparatus comprises an elongated tubular body having a gas inlet at one end and a gas outlet at the other end, first and second catalytic converter cores disposed in said tubular body whereby the gas stream is forced to flow through said first and second cores successively, each of said cores being formed of a corrugated metal strip defining cells through which such gas stream must flow and having a porous refractory metal oxide coating on at least one surface thereof and a catalyst metal adsorbed on the surface of said refractory metal oxide, the first catalytic core having a noble metal catalyst adsorbed on said refractory metal oxide coating, and the second catalytic core having a catalyst adsorbed on said refractory metal oxide coating, and means for introducing gaseous ammonia into the gas stream between said first and second catalytic converter cores.
Claim 37
Independent Claim
162 words
An apparatus for removing nitrogen oxides from a gas stream and converting such oxides to nitrogen and water, which apparatus comprises an elongated tubular body having a gas inlet at one end and a gas outlet at the other end, first and second catalytic converter cores disposed in said tubular body whereby the gas stream is forced to flow through said first and second cores successively, each of said cores being formed of a corrugated metal strip defining cells through which such gas stream must flow and having a porous refractory metal oxide coating on at least one surface thereof and a catalyst metal adsorbed on the surface of said refractory metal oxide, the first catalytic core having a noble metal catalyst adsorbed on said refractory metal oxide coating, and the second catalytic core having a catalyst adsorbed on said refractory metal oxide coating, and means for introducing gaseous ammonia into the gas stream between said first and second catalytic converter cores.
References Cited (Backward Citations)
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