HC-SCR on Silver-Based Catalyst: From Synthetic Gas Bench to Real Use

Event
SAE International Powertrains, Fuels and Lubricants Meeting
Authors Abstract
Content
The challenge for decreasing the emissions of compression ignition engines now remains mainly on NOx control. If the Lean NOx Trap (LNT) and Selective Catalytic Reduction by Urea (Urea-SCR) are very efficient, their extra-cost and management are a major issue for the OEMs. In that context, the selective catalytic reduction by hydrocarbons (HC-SCR) appears to be an interesting alternative solution, with a more limited NOx conversion efficiency but an easier packaging (diesel fuel as a reductant) and a limited price (reasonable coating cost / no PGM).
In the framework of the RedNOx project, a prototype catalyst made of 2% silver on Alumina coated on cordierite was manufactured and tested on a synthetic gas bench. In parallel, an exhaust implementation study has been led to ensure the most suited conditions for injection. Thanks to SGB and simulation results, adapted engine tests have been designed and performed.
If the results on SGB are consistent with the literature with a maximum NOx conversion reaching about 70% and an operating range between 300 and 500°C, first engine results were very disappointing showing efficiencies lower than 15% for all the operating points. Three guidelines for improving these results were identified and studied:
  • The way the reductant is introduced in the exhaust, especially the discontinued HC delivery due to the injection pattern
  • The gas velocity: unusual small GHSV values for automotive applications are needed to ensure a good NOx conversion rate.
  • The nature of the used reductant. Diesel fuel (ULSD) compared with decane lowers the efficiency, but synthetic Diesel fuel (SD) and, moreover, ethanol, largely improve it, especially for high GHSV.
Meta TagsDetails
DOI
https://doi.org/10.4271/2011-01-2092
Pages
15
Citation
Frobert, A., Raux, S., Lahougue, A., Hamon, C. et al., "HC-SCR on Silver-Based Catalyst: From Synthetic Gas Bench to Real Use," SAE Int. J. Fuels Lubr. 5(1):389-398, 2012, https://doi.org/10.4271/2011-01-2092.
Additional Details
Publisher
Published
Aug 30, 2011
Product Code
2011-01-2092
Content Type
Journal Article
Language
English