(6bi) Novel Catalytic Materials for Efficient Chemistry - Elucidation of Fundamental Structure-Activity Relationships

Our modern world is dependent on a range of chemical transformations that are carried out using heterogeneous catalysts. Monometallic catalysts are limited in their performance while supported bimetallic catalysts offer many advantages in activity, selectivity, and/or stability for a variety of chemistries. In order to further improve performance and develop new bimetallic catalysts for challenging transformations, fundamental structure-activity relationships must be elucidated. By understanding the mechanisms by which reactivity enhancement occurs, we gain insight which informs rational catalyst design of novel materials.

My Ph.D. research under Professor James A. Dumesic has focused on tuning catalytic performance through a precision synthesis approach for bimetallic materials. By using controlled surface reactions to synthesize bimetallic catalysts, I have elucidated structure activity relationships for Pd-based bimetallic catalysts for hydrogenation and amination reactions. Conventional catalyst synthesis techniques, such as impregnation, often result in catalysts with monometallic species within the bimetallic system. I showed that this challenge can be overcome and uniform, bimetallic active sites can be formed by selectively depositing a promoting metal onto a parent catalyst. Using catalysts synthesized by this approach, I demonstrated that Au-Pd active sites are more active than either Pd or Au sites for the gas phase amination of 1-hexanol. Using FTIR, STEM-EDS, and XAS techniques, I concluded that the resulting Pd structure varies with catalyst composition, and that highly active, isolated Pd species can be formed at low Pd loadings.

Additionally, I adapted and applied controlled surface reactions for the synthesis of AgPd catalysts on carbon, SiO₂, and TiO₂ supports and demonstrated that the selective deposition of the promoting metal is dependent on the support. Furthermore, the support influences the bimetallic active site structure and resulting selectivity for the hydrodechlorination of 1,2-dichloroethane. Using spectroscopic techniques, I demonstrated that formation of uniform bimetallic structures was most effective for AgPd/TiO₂, resulting in Pd that is well isolated and diluted in the Ag. Over AgPd/TiO₂,a high selectivity to the desired ethylene is achieved, while a high selectivity to undesired ethane is achieved over AgPd/SiO₂,which was determined to have both monometallic and bimetallic structures. Thus, I showed that by tuning Pd surface structures, the selectivity can be modulated between ethane and ethylene.

My work is currently being expanded to investigate selective hydrogenation reactions using AgPd and AuPd catalysts and develop structure-activity relationships for this chemistry. By combining a highly controlled approach to synthesizing well defined bimetallic active sites and advanced characterization techniques with fundamental reaction kinetics studies, we can develop structure-activity relationships which inform further catalyst improvements. My future research program will use these fundamental approaches to understand the active site and develop novel catalytic materials for a variety of chemical transformations.

Teaching Interests:

During my time as a PhD student, I have developed skills in and explored my passion for teaching in several ways. I served as a teaching assistant for the undergraduate Transport Lab and was awarded a student-nominated TA Award for the course. I also served as the teaching assistant for both undergraduate Reactor Design and Kinetics and graduate Kinetics and Catalysis, for which I lead course discussions and developed homework and exam questions with the goal of fostering a deeper understanding of course material for students.

I further explored teaching and mentoring through the Delta Program in Research, Teaching, and Learning. I studied constructivist pedagogical approaches and active learning techniques, and refined my skills in effective assessments, something I believe to be key in ensuring student learning. I also conducted a teaching-as-research project to identify misconceptions that undergraduate students hold on the topic of catalysis, as misconceptions can be challenging to overcome and replace with correct understanding. Through this project, I gained experience in collecting data to answer questions about student learning and am motivated to continue this practice in my future classrooms to promote deep understanding in my students. This work culminated in a Delta Certificate in Research, Teaching, and Learning.

Additionally, as a WISCIENCE Mentoring Fellow, I cultivated best practices for mentoring in a research setting and have mentored 4 undergraduate students and 2 high school students in the lab. Work from two of these students contributed to publications. I also facilitated Entering Research, a course to help undergraduate students gain communication skills necessary to be successful in research. These experiences have prepared me to be an effective teacher in the classroom and active mentor to students in the lab by giving me tools to continually evaluate and improve my teaching.

From these experiences, my teaching philosophy is focused on three aspects: student engagement, inclusion, and a student-centered classroom. I believe that incorporating active learning approaches is key to ensuring effective learning. The next generation of chemical engineers will face a wide range of challenges in changing feedstocks, the need for improved efficiency, and more, and I aim to guide student development of problem solving skills through hands-on laboratory experiences and project work. I will also encourage students to think critically and take leadership over their own learning through metacognition. I am deeply passionate about teaching and plan to continue to apply best practices from literature on teaching and learning to my own classroom. I am interested in teaching material balances and unit operations courses, as these serve as the foundation for a comprehensive chemical engineering education. I am also interested in teaching kinetics and catalysis courses at both the undergraduate and graduate level and would be interested in developing elective courses on microkinetic modeling or material science for chemical engineers. By incorporating topics from current research into my classroom, I hope to inspire students to build upon their chemical engineering education and develop the skills needed to be the next generation of problem solvers.