• Video
  • 18-Jun-2012 11:49 EDT

Brief Investigation of SCR High Temperature N2O Production

00:18:03
Length:

Purchase Required to View Video

Short Preview Below

Nitrous Oxide (N2O) is a greenhouse gas with a Global Warming Potential (GWP) of 298-310 [1,2] (298-310 times more potent than carbon dioxide (CO2)). As a result, any aftertreatment system that generates N2O must be well understood to be used effectively. Under low temperature conditions, N2O can be produced by Selective Catalytic Reduction (SCR) catalysts. The chemistry is reasonably well understood with N2O formed by the thermal decomposition of ammonium nitrate [3]. Ammonium nitrate and N2O form in oxides of nitrogen (NOx) gas mixtures that are high in nitrogen dioxide (NO2)[4]. This mechanism occurs at a relatively low temperature of about 200°C, and can be controlled by maintaining the nitric oxide (NO)/NO2 ratio above 1. However, N2O has also been observed at relatively high temperatures, in the region of 500°C. The ammonium nitrate mechanism is unsatisfactory because ammonium nitrate is not stable above about 210°C, and yet N2O formation can begin close to 480°C and increase above 500°C for some formulations.

The objective of this brief study was to collect data showing under what conditions high temperature N2O is formed, and to provide evidence towards understanding the mechanism that leads to high temperature N2O production.

Presenter
Gordon J. Bartley, Southwest Research Institute

Buy
Select
Price
List
Purchase to View
$19.00
Learn More
Technical Paper / Journal Article
2012-04-16
TECH PPR 2012 CONG SP-2324
Share
HTML for Linking to Page
Page URL
Grade
Rate It
No ratings yet

View More Video

Video
2012-06-18
Currently, two consolidated aftertreatment technologies are available for the reduction of NOx emissions from diesel engines: Urea SCR (Selective Catalytic Reduction) systems and LNT (Lean NOx Trap) systems. Urea SCR technology, which has been widely used for many years at stationary sources, is becoming nowadays an attractive alternative also for light-duty diesel applications. However, SCR systems are much more effective in NOx reduction efficiency at high load operating conditions than light load condition, characterized by lower exhaust gas temperatures.
Video
2012-06-18
In this project funded by the Bayerische Forschungsstiftung two fundamental investigations had been carried out: first a new N-rich liquid ammonia precursor solution based on guanidine salts had been completely characterized and secondly a new type of side-flow reactor for the controlled catalytic decomposition of aqueous NH3 precursor to ammonia gas has been designed, applied and tested in a 3 liter passenger car diesel engine. Guanidine salts came into the focus due to the fact of a high nitrogen-content derivate of urea (figure 1). Specially guanidinium formate has shown extraordinary solubility in water (more than 6 kg per 1 liter water at room temperature) and therefore a possible high ammonia potential per liter solution compared to the classical 32.5% aqueous urea solution (AUS32) standardized in ISO 22241 and known as DEF (diesel emission fluid), ARLA32 or AdBlue®. Additionally a guanidine based formulation could be realized with high freezing stability down to almost ?30 °C (?

Related Items

Article
2016-08-24
Technical Paper / Journal Article
2011-04-12