High Performance NH
SCR Zeolite Catalysts for Treatment of NO
in Emissions from Off-Road Diesel Engine
The leading approach for reduction of NOx from diesel engines is selective catalytic reduction employing urea as a reductant (NH₃- or urea-SCR). For passenger vehicles, the best known NH₃-SCR catalysts are Cu-ZSM-5 and Fe-ZSM-5 and have been shown to function very well in a narrow temperature range. This technology is not directly transferable to off-road diesel engines which operate under a different duty cycle resulting in exhaust with different fractions of components than are present in passenger vehicle emissions. Our results show that Cu-ZSM-5 exhibits 90% NOx reduction efficiency in 250-450°C range while Fe-ZSM-5 is highly effective in 350-550°C range for off-road engines. However, a combination of these catalysts cannot efficiently reduce NOx in 150-650°C which is the desirable range for deployment in off-road diesel engines. In our efforts to increase the effective range of these catalysts, we initiated efforts to modify these catalysts by catalyst promoters. In this paper, we describe our results on synthesis, characterization, and testing of new zeolites prepared by selective partial replacement of framework aluminum with trivalent ions. The new hetero-bimetallic MFI-zeolite, formed by partial replacement of framework aluminum with indium, exhibits high NOx conversion performance at 150°C. The impact of aging on the NOx reduction efficiencies of these catalysts is also presented.
Citation: Narula, C., Yang, X., Bonnesen, P., and Hagaman, E., "High Performance NH3 SCR Zeolite Catalysts for Treatment of NOx in Emissions from Off-Road Diesel Engine," SAE Technical Paper 2011-01-1330, 2011, https://doi.org/10.4271/2011-01-1330. Download Citation
Chaitanya Narula, Xiaofan Yang, Peter Bonnesen, Edward Hagaman
Oak Ridge National Laboratory, Oak Ridge Associated Universities Inc.
SAE 2011 World Congress & Exhibition
Diesel Exhaust Emission Control, 2011-SP-2318