281076 NOx Reduction and Ammonia Generation Over Three-Way Catalysts and LNTs for Use in Lean Gasoline Vehicles Equipped with SCR

Monday, October 29, 2012: 4:33 PM
316 (Convention Center )
Chris Digiulio1, Todd J. Toops2, James E. Parks2, Josh A. Pihl2 and Michael D. Amiridis1, (1)Department of Chemical Engineering, University of South Carolina, Columbia, SC, (2)Fuels, Engines and Emissions Research Center, Oak Ridge National Laboratory, Knoxville, TN

The introduction of lean gasoline vehicles and their associated improved fuel efficiency are limited due to the difficulty in meeting emissions requirements; specifically the reduction of NOx.  This effort addresses NOx, CO, and hydrocarbon emission control challenges and studies a variety of catalytic approaches to meet them under typical lean gasoline conditions.  Currently only bench reactor results will be discussed.  A three-way catalyst (TWC), which will be required on the system due to periodic stoichiometric operation, will not be able to reduce NOx under the lean conditions.  However, under mildly rich conditions it has been shown that TWCs can aggressively convert NOx to NH3.  This ammonia when combined with a zeolite-based SCR system can be stored during these rich conditions and used to convert NOx during lean operation.  Results evaluating NH3 formation over a variety of TWCs will be presented.  Additionally, Lean NOx Traps (LNT) have illustrated the ability to make high levels of NH3 during cyclic operation.  We will show results on a commercially relevant LNT and how lean-rich timing impacts NH3 generation, including the potential benefits and problems associated with including NOx storage capacity in TWC formulation.

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See more of this Session: Future Automotive Catalysis
See more of this Group/Topical: Catalysis and Reaction Engineering Division