US4212853A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the treatment of exhaust gases containing nitrogen oxides
Assignee: Chiyoda Corp
•
Filing: 1978-12-27
•
Granted: 1980-07-15
•
Expires: 1998-12-27
Abstract
Abstract Exhaust or waste gas containing nitrogen oxides is contacted with an aqueous solution containing urea and a catalytic amount of bromine or/and chlorine ion.
Inventors
- 👤 Suguru Fukui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:25
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/54; B01D53/56
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
88 words
A method of treating exhaust gas containing nitrogen oxides, comprising the steps of forming a neutral aqueous solution containing urea and a catalyst for the removal of said nitrogen oxides from said exhaust gas, said catalyst being a catalytic amount of at least one halogen ion selected from the group consisting of bromine and chlorine ions, and contacting said neutral aqueous solution with exhaust gas containing nitrogen oxides, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 2
Independent Claim
88 words
A method of treating exhaust gas containing nitrogen oxides, comprising the steps of forming a neutral aqueous solution containing urea and a catalyst for the removal of said nitrogen oxides from said exhaust gas, said catalyst being a catalytic amount of at least one halogen ion selected from the group consisting of bromine and chlorine ions, and contacting said neutral aqueous solution with exhaust gas containing nitrogen oxides, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein said neutral aqueous solution contains about 0.01 to about 30% by weight of urea and at least about 0.01 gram ion/liter of said halogen ion.
Claim 4
Dependent Claim
12 words
The method of claim 1 wherein said halogen ion is bromine ion.
Claim 5
Independent Claim
124 words
A method of treating exhaust gas containing nitrogen oxides in an NO 2 /NO ratio of less than about 1, comprising partially oxidizing an exhaust gas containing nitrogen oxides in an NO 2 /NO ratio of less than about 1 to increase the NO 2 /NO ratio to about 1, forming a neutral aqueous solution containing urea and a catalyst for the removal of said nitrogen oxides from said exhaust gas, said catalyst being a catalytic amount of at least one halogen ion selected from the group consisting of bromine and chlorine ions, and contacting the partially oxidized gas with said neutral aqueous solution, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 6
Independent Claim
124 words
A method of treating exhaust gas containing nitrogen oxides in an NO 2 /NO ratio of less than about 1, comprising partially oxidizing an exhaust gas containing nitrogen oxides in an NO 2 /NO ratio of less than about 1 to increase the NO 2 /NO ratio to about 1, forming a neutral aqueous solution containing urea and a catalyst for the removal of said nitrogen oxides from said exhaust gas, said catalyst being a catalytic amount of at least one halogen ion selected from the group consisting of bromine and chlorine ions, and contacting the partially oxidized gas with said neutral aqueous solution, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 7
Dependent Claim
31 words
The method of claim 4 wherein said neutral aqueous solution contains about 0.01 to about 30% by weight of urea and at least about 0.01 gram ion/liter of said halogen ion.
Claim 8
Dependent Claim
12 words
The method of claim 4 wherein said halogen ion is bromine ion.
Claim 9
Independent Claim
137 words
A method of treating exhaust gas resulting from the combustion of petroleum fuels or fossil fuels and containing from about 10 to 1,000 ppm of nitrogen oxides, comprising adding to an aqueous solution of urea acidified with a strong mineral acid, a neutral salt containing chlorine or bromine ion, which will not substantially hydrolyze in said solution, in an amount more than equivalent to said strong mineral acid, thereby forming an aqueous solution containing urea, mineral acids, including hydrochloric acid or hydrobromic acid, and a catalytic amount of chlorine ion or bromine ion other than the chlorine ion or bromine ion forming said hydrochloric acid or hydrobromic acid, and contacting the resultant solution with said exhaust gas, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 10
Independent Claim
137 words
A method of treating exhaust gas resulting from the combustion of petroleum fuels or fossil fuels and containing from about 10 to 1,000 ppm of nitrogen oxides, comprising adding to an aqueous solution of urea acidified with a strong mineral acid, a neutral salt containing chlorine or bromine ion, which will not substantially hydrolyze in said solution, in an amount more than equivalent to said strong mineral acid, thereby forming an aqueous solution containing urea, mineral acids, including hydrochloric acid or hydrobromic acid, and a catalytic amount of chlorine ion or bromine ion other than the chlorine ion or bromine ion forming said hydrochloric acid or hydrobromic acid, and contacting the resultant solution with said exhaust gas, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 11
Dependent Claim
32 words
The method of claim 7 wherein said acidic aqueous solution contains about 0.01 to about 30% by weight of urea and at least about 0.01 gram ion/liter of chlorine or bromine ion.
Claim 12
Dependent Claim
12 words
The method of claim 7 wherein said neutral salt contains bromine ion.
Claim 13
Dependent Claim
12 words
The method of claim 7 wherein said neutral salt contains chlorine ion.
Claim 14
Independent Claim
145 words
A method of treating exhaust gas containing nitrogen oxides in an NO 2 /NO ratio of less than about 1, comprising partially oxidizing said gas to increase the NO 2 /NO ratio to about 1, adding to an aqueous solution of urea acidified with a strong mineral acid, a neutral salt containing chlorine or bromine ion, which will not substantially hydrolyze in said solution, in an amount more than equivalent to said strong mineral acid, thereby forming an aqueous solution containing urea, mineral acids, including hydrochloric acid or hydrobromic acid, and a catalytic amount of chlorine ion or bromine ion other than the chlorine ion or bromine ion forming said hydrochloric acid or hydrobromic acid, and contacting the resultant solution with said partially oxidized gas, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 15
Independent Claim
145 words
A method of treating exhaust gas containing nitrogen oxides in an NO 2 /NO ratio of less than about 1, comprising partially oxidizing said gas to increase the NO 2 /NO ratio to about 1, adding to an aqueous solution of urea acidified with a strong mineral acid, a neutral salt containing chlorine or bromine ion, which will not substantially hydrolyze in said solution, in an amount more than equivalent to said strong mineral acid, thereby forming an aqueous solution containing urea, mineral acids, including hydrochloric acid or hydrobromic acid, and a catalytic amount of chlorine ion or bromine ion other than the chlorine ion or bromine ion forming said hydrochloric acid or hydrobromic acid, and contacting the resultant solution with said partially oxidized gas, said process being carried out at a temperature of between about ambient temperature and the boiling point of the solution.
Claim 16
Dependent Claim
33 words
The method of claim 1 wherein said acidic aqueous solution contains about 0.01 to about 30% by weight of urea and at least about 0.01 gram ion/liter of said chlorine or bromine ion.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-07-15 | 1984-01-14 | 1984-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-15 | 1988-01-14 | 1988-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-15 | 1992-01-14 | 1992-07-15 | $7700.00 | Window Closed / Lapsed |