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US5260043A
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Catalytic reduction of NOx and carbon monoxide using methane in the presence of oxygen
Assignee: Air Products and Chemicals Inc
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Filing: 1992-08-13
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Granted: 1993-11-09
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Expires: 2012-08-13
Abstract
Abstract The invention describes a process for catalytically destroying NOx and carbon monoxide present in oxygen-containing combustion products wherein methane serves as a reductant. The process comprises combusting a fuel source in the presence of oxygen to form combustion products comprising nitrogen oxides, carbon monoxide and oxygen; introducing methane into the combustion products in an amount such that the total amount of methane to nitrogen oxides present, expressed as a ratio, by volume is greater than about 0.1; and reacting the nitrogen oxides, carbon monoxide, methane and oxygen in the presence of an exchanged crystalline zeolite under conditions sufficient to convert the nitrogen oxides and carbon monoxide to gaseous nitrogen, water and carbon oxides. Suitable catalysts include zeolites having a silicon to aluminum ratio of greater than or equal to about 2.5 which zeolites are exchanged with a cation selected from the group consisting of gallium, niobium, cobalt, nickel, iron, chromium, rhodium and manganese.
Inventors
- 👤 Yuejin Li
- 👤 John N. Armor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:19
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9445; B01D53/945; B01D53/38; B01D53/74; B01D53/86; B01D53/8621; B01D53/8625; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9418; B01J; B01J29/00; B01J29/04; B01J29/06; B01J29/061; F; F01; F01N; F01N13/00; F01N13/009; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; B01D2251/00; B01D2251/20; B01D2251/208; B01D2255/00; B01D2255/10; B01D2255/102; B01D2255/1023; B01D2255/1025; B01D2255/20; B01D2255/207; B01D2255/2073; B01D2255/20746; B01D2255/20753; B01D2255/50; B01D2255/90; B01D2255/912; F01N2610/00; F01N2610/03; Y; Y02; Y02C; Y02C20/00; Y02C20/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
143 words
A process for destroying nitrogen oxides and carbon monoxide in a combustion product, which process comprises: (a) combusting a fuel source in the presence of oxygen to form a combustion product comprising nitrogen oxides, carbon monoxide and oxygen; (b) introducing methane into the combustion products in an amount such that the total amount of methane to nitrogen oxides present expressed as a ratio, by volume is greater than 0.1; and (c) reacting the combustion products, methane and oxygen in the presence of a catalyst comprising a crystalline zeolite having a silicon to aluminum ratio of greater than or equal to about 2.5 which is exchanged with a cation selected from the group consisting of cobalt, nickel, iron, chromium, rhodium, gallium and manganese, under conditions sufficient to convert a portion of the nitrogen oxides and carbon monoxide to gaseous nitrogen, water and carbon dioxide.
Claim 2
Dependent Claim
143 words
A process for destroying nitrogen oxides and carbon monoxide in a combustion product, which process comprises: (a) combusting a fuel source in the presence of oxygen to form a combustion product comprising nitrogen oxides, carbon monoxide and oxygen; (b) introducing methane into the combustion products in an amount such that the total amount of methane to nitrogen oxides present expressed as a ratio, by volume is greater than 0.1; and (c) reacting the combustion products, methane and oxygen in the presence of a catalyst comprising a crystalline zeolite having a silicon to aluminum ratio of greater than or equal to about 2.5 which is exchanged with a cation selected from the group consisting of cobalt, nickel, iron, chromium, rhodium, gallium and manganese, under conditions sufficient to convert a portion of the nitrogen oxides and carbon monoxide to gaseous nitrogen, water and carbon dioxide.
Claim 3
Dependent Claim
31 words
The process according to claim 1 wherein the zeolite is exchanged with from 0.1 to about 15 wt % of the cation based upon the total weight of the exchanged zeolite.
Claim 4
Dependent Claim
18 words
The process according to claim 2 wherein the zeolite comprises a MOR, MFI or FER structure type zeolite.
Claim 5
Dependent Claim
20 words
The process according to claim 1 wherein the combusting of the fuel source is effected in an internal combustion engine.
Claim 6
Dependent Claim
24 words
The process according to claim 4 wherein the catalyst further comprises a separate stage comprising a platinum or palladium catalyst on an inert support.
Claim 7
Dependent Claim
33 words
The process according to claim 4 wherein the fuel source comprises one or more components selected from the group consisting of gaseous and liquid hydrocarbons having from one to about fifteen carbon atoms.
Claim 8
Dependent Claim
20 words
The process according to claim 1 wherein the combusting of the fuel source is effected in an external combustion device.
Claim 9
Dependent Claim
39 words
The process according to claim 7 wherein the fuel source comprises one or more components selected from the group consisting of coal, oil, refuse, natural gas and gaseous and liquid hydrocarbons having from one to about fifteen carbon atoms.
Claim 10
Dependent Claim
37 words
The process according to claim 1 wherein the reacting of the combustion products in the presence of the catalyst is conducted at temperatures ranging from 250° to 700° C. and pressures ranging from 0.5 to 300 atmospheres.
Claim 11
Dependent Claim
32 words
The process according to claim 3 wherein the reacting is conducted in a fixed bed reactor with a gas hourly space velocity ranging from 1,000 hr -1 to 100,000 hr -1 .
Claim 12
Dependent Claim
55 words
The process according to claim 2 wherein the exchanged zeolite is further exchanged with from 0.01 to about 2 wt % , based upon total weight of the exchanged zeolite, with an additional metal selected from the third period transition metals or Groups 5, 6, 7 and 11 of the Periodic Table of the Elements.
Claim 13
Dependent Claim
51 words
The process according to claim 2 where the metal-exchanged zeolite is impregnated with from 0.01 wt % to 15 wt % , based upon the total weight of the impregnated metal-exchanged zeolite, of an anionic or neutral species containing a metal selected from Group 5,6,7 and 11 of the Periodic Table.
Claim 14
Dependent Claim
31 words
The process according to claim 12 wherein the species to be impregnated onto the metal-exchanged zeolite contains a metal selected from the group consisting of niobium, molybdenum, silver, vanadium and manganese.
Claim 15
Dependent Claim
30 words
The process according to claim 2 wherein the metal-exchanged zeolite is impregnated with from 0.1 to 23 wt % alumina based upon the total weight of the impregnated metal-exchanged zeolite.
Claim 16
Dependent Claim
24 words
The process according to claim 3 wherein the MOR structure type zeolite is selected from the group consisting of mordenite, Na-D, Ptilolite and Zeolon.
Claim 17
Dependent Claim
26 words
The process according to claim 3 wherein the MFI structure type zeolite is selected from the group consisting of ZSM-5, Silicalite-1, Silicalite, Zeta-1, Zeta-3 and AZ-1.
Claim 18
Dependent Claim
25 words
The process according to claim 3 wherein the FER structure type zeolite is selected from the group consisting of ferrierite, SR-D, Fu-9, NU-23 and ZSM-35.
Claim 19
Dependent Claim
12 words
The process according to claim 3 wherein the catalyst is Gallium-exchanged ZSM-5.
Claim 20
Dependent Claim
17 words
The process according to claim 3 wherein the catalyst is Co-ZSM-5 onto which alumina has been precipitated.
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