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<meta http-equiv="Content-Type" content="text/html; charset=Windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif; "><div><br></div><span id="OLK_SRC_BODY_SECTION"><div xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><div lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal" align="center" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-align:center;line-height:150%;background:white"><a name="_Toc473187185"></a><a name="_Toc480840318"></a><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">PhD DEFENSE STUDENT: </span></b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">Mengmeng
Li</span><span style="font-size: 12pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; "><o:p></o:p></span></p><p class="MsoNormal" align="center" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-align:center;line-height:150%;background:white"><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">DATE: </span></b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">Friday,<b></b>June 2, 2017</span><span style="font-family: 'Times New Roman', serif; color: black; "><o:p></o:p></span></p><p class="MsoNormal" align="center" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-align:center;line-height:150%;background:white"><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">TIME: </span></b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">2:00 PM</span><span style="font-family: 'Times New Roman', serif; color: black; "><o:p></o:p></span></p><p class="MsoNormal" align="center" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-align:center;line-height:150%;background:white"><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">PLACE:</span></b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; "> Electrical & Computer Engineering Conference
Room (N 328)</span><span style="font-family: 'Times New Roman', serif; color: black; "><o:p></o:p></span></p><p class="MsoNormal" align="center" style="margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:150%;background:white"><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">DISSERTATION CHAIR:
</span></b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">Dr. Michael P. Harold
</span><span style="font-family: 'Times New Roman', serif; color: black; "><o:p></o:p></span></p><div class="MsoNormal" align="center" style="margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:150%;background:white"><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; "><hr size="2" width="100%" align="center"></span></div><p class="MsoNormal" align="center" style="margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:150%;background:white"><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">TITLE:<o:p></o:p></span></b></p><p class="MsoNormal" align="center" style="margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:150%;background:white"><b><span style="font-size: 14pt; line-height: 150%; font-family: 'Times New Roman', serif; color: black; ">Spatio-temporal Features of Combined NOx Storage and Reduction and Selective Catalytic Reduction<o:p></o:p></span></b></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;text-align:justify;text-indent:.25in;line-height:normal"><b><span style="font-size: 12pt; font-family: 'Times New Roman', serif; letter-spacing: -0.5pt; "><o:p> </o:p></span></b></p><p class="MsoNormal" style="text-align:justify;text-indent:.25in;line-height:200%"><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; ">Emerging more stringent vehicle emissions rules for non-methane organic gases (NMOG) plus NOx and demanding improvement of vehicle fuel economy have increased the application
of lean-burn engine technology. Therefore, the research and development of the commercial deNOx technology, i.e. NOx storage and reduction (NSR, also referred as LNT), selective catalytic reduction (SCR) and passive SCR system (synergy of LNT and SCR), has
been promoted. This dissertation focuses on understanding NOx reduction and NH<sub>3</sub> generation for the standalone LNT and a passive SCR system spanning kinetics and reactor performance studies. Systematic bench reactor experiments were conducted to
study the impact of catalyst composition, reductant agents, and operating strategies. Furthermore, a global kinetic model combined with a low-dimensional monolithic reactor model was developed aiming to optimize the design and operation strategies of the similar
three-way NOx storage catalyst (TWNSC).<o:p></o:p></span></p><p class="MsoNormal" style="text-align:justify;text-indent:.25in;line-height:200%"><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; ">Starting with performance evaluation of model LNT, SCR, and LNT+SCR catalysts, simulated exhaust gas containing C<sub>3</sub>H<sub>6</sub> or CO reductant was used over a
range of feed concentrations and temperatures, and gas hourly space velocities (GHSV). Spatially-resolved mass spectrometry (SpaciMS) was applied to construct spatio-temporal concentration and temperature profiles spanning LNT+SCR system. The spatial profiles
are useful in pinpointing the LNT length that gives a product with NH<sub>3</sub>/NOx = 1 stoichiometry beneficial for promoting NOx reduction in the SCR. The combination of an overall GHSV = 135k h<sup>-1</sup> and T<sub>f</sub> = 350
<sup>o</sup>C generates a SCR feed from the LNT that results in the highest incremental cycle-averaged NOx conversion in the SCR (~30%) and high cycle-averaged conversions of NOx (~90%) and C<sub>3</sub>H<sub>6</sub> (~80%). The temperature measurements reveal
a large exotherm caused by the C<sub>3</sub>H<sub>6</sub> oxidation manifested as a propagating temperature front.
<o:p></o:p></span></p><p class="MsoNormal" style="text-align:justify;text-indent:.25in;line-height:200%"><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; ">The impact of reductant type, specifically carbon-free (H<sub>2</sub>), olefin (C<sub>3</sub>H<sub>6</sub>) and alkane (C<sub>3</sub>H<sub>8</sub>), in rapid lean-rich cycling
over a LNT catalyst was investigated over a range of feed temperatures and cycle times.
<a name="_Hlk482126255">The NOx conversion is enhanced at elevated temperatures (T<sub>f</sub> > 350<sup> o</sup>C) independent of reductant type by decreasing the cycle time.</a> While the opposite trend was observed at intermediate temperatures (T<sub>f
</sub>= 250 – 325 <sup>o</sup>C) with C<sub>3</sub>H<sub>8</sub> attributed to kinetic limitations of the C<sub>3</sub>H<sub>8</sub> dehydrogenation. The contrasting features obtained with H<sub>2</sub>, C<sub>3</sub>H<sub>6</sub>, and C<sub>3</sub>H<sub>8</sub>
during cyclic operation and steady-state in-situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) help provide a deeper understanding of the underlying mechanism.<o:p></o:p></span></p><p class="MsoNormal" style="text-align:justify;text-indent:.25in;line-height:200%"><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; ">Finally, a systematic kinetic study was carried out to develop the global kinetic model to capture the NOx reduction performance based on the parallel experimental study conducted
by Malamis et al. [1]. The simulation of the cyclic condition has well captured the cycle-averaged NOx conversion and NH<sub>3</sub> selectivity, the transient species concentrations and temperature profiles over a wide range of total cycle time (10s - 200s)
at 50% duty cycle rich.<o:p></o:p></span></p><p class="MsoNormal" style="text-align:justify;line-height:200%"><b><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; ">Reference<o:p></o:p></span></b></p><p class="MsoNormal" style="margin-left:32.0pt;text-indent:-32.0pt;line-height:200%;text-autospace:none"><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; ">[1] S. A. Malamis, M. Li, W. S. Epling, M. P. Harold, C. Dimaggio, and K. Premchan, “Steady State and Lean-Rich Cycling Characterization of a Three-Way NO<sub>X</sub>
Storage Catalyst (TWNSC).” . In preparation, 2017.<o:p></o:p></span></p><p class="MsoNormal" style="text-align:justify;text-indent:.25in;line-height:200%"><span style="font-size: 12pt; line-height: 200%; font-family: 'Times New Roman', serif; "><o:p> </o:p></span></p></div></div></div></span><style><!--
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