[CCoE Notice] PhD Defense: Fast Cycling NOx Storage and Reduction on Lean NOx Trap Catalytic Reactor

[Grayson, Audrey A]

PhD DEFENSE STUDENT: Allen Wei-Lun Ting

DATE: Tuesday, May 1, 2018

TIME: 2:30 PM

PLACE:  Chemical Engineering Conference Room

DISSERTATION CHAIRs: Dr. Michael Harold and Dr. Dan Luss

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TITLE:

Fast Cycling NOx Storage and Reduction on Lean NOx Trap Catalytic Reactor



An experimental and modeling study describes fast cycling NOx storage and reduction (NSR) with H2 and C3H6 as reductants on a Pt/BaO/CeO2/Al2O3 lean NOx trap (LNT) catalyst for emission control of lean burn vehicles. Experiments and modeling reveal NOx conversion enhancement for cycle times less than 10 s (fast cycling) compared to the longer cycle times of ~1 min, typical of conventional NSR. The more frequent storage and regeneration of fast cycling increases the utilization of stored NOx capacity by decreasing NOx breakthrough during the lean phase. This NOx conversion enhancement of up to 45% (absolute) is independent of reductant type.

Involvement of a surface N-containing oxygenate pathway is indicated by the occurrence of secondary peaks of N2O, N2, and CO2 during the rich to lean switch, resulting from mainly oxidation of adsorbed intermediates. Reactivity of the intermediates are also investigated. Modeling results can capture most of the experimental trends. Proposed HC-intermediate (selected as C2H3NCO) pathway can predict the experimental double peaks of N2, while formation of which consumes ~2.5 times C3H6 according to the stoichiometry number, resulting in less NOx reduction efficiency than traditional C3H6 reduction pathway.

In sum, through both experiments and modeling the traditional NOx reduction pathway is the most effective and the better utilization of the storage site is the most important factor in NOx reduction enhancement during fast cycling.
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