US5234670A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reduction of nitrogen oxide in effluent gases using NCO radicals
Assignee: Cummins Power Generation Inc
•
Filing: 1991-03-12
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Granted: 1993-08-10
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Expires: 2011-03-12
Abstract
Abstract A process is described for reducing the nitrogen content of a post combustion gas which comprises the steps of (A) generating NCO free radicals, and thereafter (B) adding the free radicals to the gas whereby the NCO free radicals react with the nitrogen oxide in the gas to form nitrogen and carbon dioxide. The NCO free radicals may be obtained from a variety of sources such as by the catalytic decomposition of cyanuric acid; the reaction of formaldehyde with nitrogen or nitric oxide; the reaction of carbon monoxide with nitrogen oxide or nitrogen or mixtures thereof; or the reaction of methanol with nitrogen in the presence of a catalyst. The NCO free radicals thus generated are effective for reducing the nitrogen oxide content of combustion gases in accordance with the process of the present invention at temperatures from ambient temperature up to about 2000° F.
Inventors
- 👤 Ralph A. Gardner-Chavis
- 👤 Michael P. May
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:45
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/74; B01D53/86; B01D53/8621; B01D53/8625; B01D53/46; B01D53/54; B01D53/56; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
136 words
A process for reducing the nitrogen oxide content of a post combustion gas which comprises the steps of (a) generating NCO free radicals by (a-1) heating cyanuric acid in the presence of a catalyst which comprises zirconium, phosphorus or a mixture of zirconium and phosphorus at a temperature of less than 1000° F., (a-2) reacting formaldehyde with nitrogen in the presence of a catalyst capable of promoting the reaction, (a-3) reacting formaldehyde with nitric oxide, (a-4) reacting carbon monoxide with nitric oxide, nitrogen or a mixture thereof, (a-5) reacting of methanol with nitrogen, or (a-6) combinations of any one of (a-1)-(a-5), and thereafter (b) adding the free radicals to the gas whereby the NCO free radicals react with the nitrogen oxide in the gas at a temperature of from ambient temperature up to about 2000° F.
Claim 2
Dependent Claim
136 words
A process for reducing the nitrogen oxide content of a post combustion gas which comprises the steps of (a) generating NCO free radicals by (a-1) heating cyanuric acid in the presence of a catalyst which comprises zirconium, phosphorus or a mixture of zirconium and phosphorus at a temperature of less than 1000° F., (a-2) reacting formaldehyde with nitrogen in the presence of a catalyst capable of promoting the reaction, (a-3) reacting formaldehyde with nitric oxide, (a-4) reacting carbon monoxide with nitric oxide, nitrogen or a mixture thereof, (a-5) reacting of methanol with nitrogen, or (a-6) combinations of any one of (a-1)-(a-5), and thereafter (b) adding the free radicals to the gas whereby the NCO free radicals react with the nitrogen oxide in the gas at a temperature of from ambient temperature up to about 2000° F.
Claim 3
Dependent Claim
27 words
The process of claim 1 wherein the gas is contacted with the NCO free radicals at a temperature of from about 300° F. to about 2000° F.
Claim 4
Dependent Claim
17 words
The process of claim 1 wherein the zirconium and phosphorus are in the plus four oxidation state.
Claim 5
Dependent Claim
11 words
The process of claim 1 wherein the catalyst comprises zirconium oxide.
Claim 6
Dependent Claim
29 words
The process of claim 1 wherein the cyanuric acid is heated in the presence of the catalyst at a temperature of from about 760° F. to about 960° F.
Claim 7
Dependent Claim
40 words
The process of claim 1 wherein the NCO free radicals are generated by reacting formaldehyde with nitrogen in the presence of a catalyst comprising vanadium, zirconium, or a mixture of vanadium and zirconium at a temperature below about 1200° F.
Claim 8
Dependent Claim
27 words
The process of claim 6 wherein the reaction between the formaldehyde and nitrogen is conducted at a temperature of from about 600° F. to about 990° F.
Claim 9
Dependent Claim
15 words
The method of claim 6 wherein the formaldehyde is obtained from the oxidation of methanol.
Claim 10
Dependent Claim
20 words
The process of claim 1 wherein the NCO free radicals are generated in (a) by reacting formaldehyde with nitric oxide.
Claim 11
Dependent Claim
29 words
The process of claim 9 wherein the reaction of formaldehyde with NO in step (a) is conducted in the presence of a catalyst comprising zirconium, cerium or mixtures thereof.
Claim 12
Dependent Claim
27 words
The process of claim 10 wherein the catalyst comprises zirconium in the plus four oxidation state, cerium in the plus four oxidation state, or a mixture thereof.
Claim 13
Dependent Claim
27 words
The process of claim 10 wherein the catalyst comprises a mixture of zirconium in the plus four oxidation state and cerium in the plus four oxidation state.
Claim 14
Dependent Claim
28 words
The process of claim 1 wherein the NCO free radicals are generated in step (a) by reaction of carbon monoxide with nitric oxide, nitrogen or a mixture thereof.
Claim 15
Dependent Claim
21 words
The process of claim 1 wherein the NCO free radicals are generated in step (a) by reaction of methanol with nitrogen.
Claim 16
Dependent Claim
105 words
The process for reducing the nitrogen oxide content of a post combustion gas stream which comprises (a) generating NCO free radicals capable of reacting with nitrogen oxide by, (a-1) decomposing cyanuric acid in the presence of a catalyst comprising zirconium, phosphorus or a mixture of zirconium and phosphorus, or (a-2) reacting formaldehyde with nitrogen in the presence of a catalyst comprising vanadium or zirconium, or a mixture thereof, and thereafter (b) adding the NCO free radicals to the gas stream at a temperature of from ambient temperature to about 2000° F. whereby the NCO free radicals react with the nitrogen oxide in the gas stream.
Claim 17
Dependent Claim
105 words
The process for reducing the nitrogen oxide content of a post combustion gas stream which comprises (a) generating NCO free radicals capable of reacting with nitrogen oxide by, (a-1) decomposing cyanuric acid in the presence of a catalyst comprising zirconium, phosphorus or a mixture of zirconium and phosphorus, or (a-2) reacting formaldehyde with nitrogen in the presence of a catalyst comprising vanadium or zirconium, or a mixture thereof, and thereafter (b) adding the NCO free radicals to the gas stream at a temperature of from ambient temperature to about 2000° F. whereby the NCO free radicals react with the nitrogen oxide in the gas stream.
Claim 18
Dependent Claim
34 words
The process of claim 15 wherein the NCO free radicals are generated in (a) by decomposing cyanuric acid in the presence of a catalyst comprising zirconium, phosphorus, or a mixture of zirconium and phosphorus.
Claim 19
Dependent Claim
17 words
The process of claim 16 wherein the zirconium and phosphorus are in the plus four oxidation state.
Claim 20
Dependent Claim
40 words
The process of claim 15 wherein the NCO free radicals are generated in (a) by reacting formaldehyde with nitrogen in the presence of a catalyst comprising vanadium or zirconium, or a mixture thereof, at a temperature below about 1200° F.
Claim 21
Dependent Claim
17 words
The process of claim 15 wherein the post combustion gas stream is an engine exhaust gas stream.
Claim 22
Dependent Claim
19 words
The method of claim 15 wherein the post combustion gas stream is a smokestack or boiler exhaust gas stream.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |