Producing ammonium carbamate and reducing nitrogen oxides
AssigneeLoughborough University
InventorsJonathan Wilson, Graham Hargrave
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Abstract
A process for reducing nitrogen oxides in an exhaust stream, such as a vehicle exhaust stream, and apparatus for carrying out the process. The process comprises providing a first composition comprising aqueous urea, a second composition comprising ammonium carbamate and an exhaust stream comprising nitrogen oxides. A process for producing the ammonium carbamate is also provided. The second composition may be introduced into the exhaust stream (10) when the exhaust stream has a temperature below a threshold temperature and the first composition may be introduced into the exhaust stream when the exhaust stream has a temperature at or above the threshold temperature.
Claims20
A process for reducing nitrogen oxides in an exhaust stream, the process comprising
- providing a first reservoir having the first composition therein, the first composition comprising aqueous urea;
- transferring a portion of the first composition along a flow path, the flow path being in communication with a second reservoir;
- heating the portion of the first composition to produce a mixture comprising ammonia, carbon dioxide and water;
- the heating taking place in the flow path or in the second reservoir;
- cooling the mixture to generate a second composition, the second composition comprising aqueous ammonium carbamate and the cooling taking place in the flow path or in the second reservoir;
- introducing the second composition from the second reservoir into an exhaust stream comprising nitrogen oxides.
An apparatus for reducing nitrogen oxides (NOx) in an exhaust stream comprising nitrogen oxides, the apparatus comprising:
- a first source of a first composition comprising urea and water, the first source comprising a first reservoir for the first composition;
- a second source of a second composition comprising ammonium carbamate, the second source comprising a second reservoir for the second composition;
- a passage for the exhaust stream;
- in which the apparatus comprises a flow control apparatus arranged to:
- selectively couple the second source to the passage to introduce the second composition into the exhaust stream;
- and
- selectively couple the first source to the passage to introduce the first composition into the exhaust stream.
Dependencies are inferred from the claim text.