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<b><span style="font-size:14.0pt; line-height:200%; color:black">PhD DEFENSE STUDENT: </span></b><span style="font-size:14.0pt; line-height:200%; color:black">Allen Wei-Lun Ting</span><span style="color:black"></span></p>
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<b><span style="font-size:14.0pt; line-height:200%; color:black">DATE: </span></b><span style="font-size:14.0pt; line-height:200%; color:black">Tuesday,<b>
</b>May 1, 2018</span><span style="color:black"></span></p>
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<b><span style="font-size:14.0pt; line-height:200%; color:black">TIME: </span></b><span style="font-size:14.0pt; line-height:200%; color:black">2:30 PM</span><span style="color:black"></span></p>
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<b><span style="font-size:14.0pt; line-height:200%; color:black">PLACE:</span></b><span style="font-size:14.0pt; line-height:200%; color:black"> Chemical Engineering Conference Room</span><span style="color:black"></span></p>
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<b><span style="font-size:14.0pt; line-height:150%; color:black">DISSERTATION CHAIRs:
</span></b><span style="font-size:14.0pt; line-height:150%; color:black">Dr. Michael Harold and Dr. Dan Luss
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<b><span style="font-size:14.0pt; line-height:200%; color:black">TITLE:</span></b></p>
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<b><span style="font-size:14.0pt; color:black">Fast Cycling NOx Storage and Reduction on Lean NOx Trap Catalytic Reactor</span></b></p>
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An experimental and modeling study describes fast cycling NOx storage and reduction (NSR) with H<sub>2</sub> and C<sub>3</sub>H<sub>6</sub> as reductants on a Pt/BaO/CeO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> 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.</p>
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Involvement of a surface N-containing oxygenate pathway is indicated by the occurrence of secondary peaks of N<sub>2</sub>O, N<sub>2</sub>, and CO<sub>2</sub> 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 C<sub>2</sub>H<sub>3</sub>NCO) pathway can predict the experimental double peaks of N<sub>2</sub>, while formation
of which consumes ~2.5 times C<sub>3</sub>H<sub>6</sub> according to the stoichiometry number, resulting in less NOx reduction efficiency than traditional C<sub>3</sub>H<sub>6</sub> reduction pathway.</p>
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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.</p>
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