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<span style="font-size:12.0pt; font-family:"Times New Roman",serif"><img width="600" height="171" id="x_Picture_x0020_3" alt="Dissertation Defense Announcement at the Cullen College of Engineering" style="width:6.25in; height:1.7812in" data-outlook-trace="F:1|T:1" src="cid:image005.jpg@01D845D5.17B10F60"></span><span style="font-size:12.0pt; font-family:"Times New Roman",serif"></span></p>
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<b><span style="font-size:16.0pt; font-family:"Times New Roman",serif; color:red; text-transform:uppercase">Site Requirements, Kinetics, and Product Inhibition</span></b></p>
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<b><span style="font-size:16.0pt; font-family:"Times New Roman",serif; color:red; text-transform:uppercase">for Alkane Oxidation over Non-stoichiometric Bulk Metal Oxides</span></b></p>
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<b><span style="font-size:16.0pt; font-family:"Times New Roman",serif; color:red; text-transform:uppercase"> </span></b></p>
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<b><span style="font-size:13.5pt; font-family:"Times New Roman",serif">Xiaohui Zhao</span></b><span style="font-size:13.5pt; font-family:"Times New Roman",serif"></span></p>
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<span style="font-family:"Times New Roman",serif">June 15, 2022; 3:00 – 5:00 PM (CST)</span></p>
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<span style="font-family:"Times New Roman",serif"><br>
Room: AERB, Room 320</span></p>
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<b><span style="font-family:"Times New Roman",serif">Committee Chair:</span></b><span style="font-family:"Times New Roman",serif"><br>
Praveen Bollini, Ph.D.</span></p>
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<b><span style="font-family:"Times New Roman",serif">Committee Members:</span></b><span style="font-size:10.0pt; font-family:"Times New Roman",serif"><br>
Jeffrey Rimer, Ph.D. <b>| </b>Lars Grabow, Ph.D. <b>|</b> Jiming Bao, Ph.D. <b>|</b> James W Harris, PhD.</span><span style="font-size:10.5pt; font-family:"Times New Roman",serif"></span></p>
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<b><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:#C8102E">Abstract</span></b><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:#C8102E"></span></p>
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<span style="font-size:12.0pt; line-height:150%; font-family:"Times New Roman",serif"> Non-stoichiometric metal oxides are important groups of materials
</span><span lang="EN-GB" style="font-size:12.0pt; line-height:150%; font-family:"Times New Roman",serif">with industrial applications such as gas sensing, energy storage, photovoltaics, and
</span><span style="font-size:12.0pt; line-height:150%; font-family:"Times New Roman",serif">catalysts for fossil fuel conversion. This dissertation aims to improve the mechanistic understanding between the non-stoichiometric structure of metal oxides and their
catalytic function for alkane oxidation and to help guide future developments and kinetic inquiries of metal oxide catalysts. The dissertation focused on Ni<sub>1-x</sub>O, a potential ethane oxidative dehydrogenation (ODH) catalyst and the catalytic function
of non-stoichiometric oxygen (NSO), a site that is associated with the nickel deficiency of the material.
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<span style="font-size:12.0pt; line-height:150%; font-family:"Times New Roman",serif"> The existence and density of two sets of active sites- NSO and lattice oxygen- were studied by CO<sub>2</sub> adsorption at 50-300 ºC. In-situ CO<sub>2</sub> titration
confirmed the activity of two active domains in both ODHE and total oxidation. In addition to CO<sub>2</sub>, H<sub>2</sub>O adsorption occurred over Ni<sub>1-x</sub>O. Both products led to strong inhibition on the reaction rate as a function of reaction contact
time or product co-feed pressure. A kinetic model that included both integral kinetic data and differential co-feed data was developed for Ni<sub>1-x</sub>O and Nb-impregnated Ni<sub>1-x</sub>O. These molecular-level understandings of the mechanistic pathways
and the intrinsic active sites will provide a fundamental base for the industrial ethylene production through oxidative pathways and guide future development of oxidative process.
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<span style="font-size:12.0pt; font-family:"Times New Roman",serif"><img width="600" height="82" id="x_Picture_x0020_4" alt="Engineered For What's Next" style="width:6.25in; height:.8541in" data-outlook-trace="F:1|T:1" src="cid:image006.jpg@01D845D5.17B10F60"></span><span style="font-size:12.0pt; font-family:"Times New Roman",serif"></span></p>
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