(6ce) Enabling Concepts in Catalysis Science

Catalysis has served as the critical enabling technology in the evolution of modern-day fuels and chemicals and in addressing environmental concerns associated with their use. The complexity of catalytic solids arises from varied architectures which range from isolated sites within crystalline porous materials to metal particles supported on amorphous metal oxides augmented by promoters, from dynamic restructuring of these surfaces under relevant process conditions, and from contributions of solvent phases or secondary environments to observed reactivity. Controlled materials synthesis, structural and chemical characterization of these materials in situ, and rigorous kinetic and isotopic studies are required to probe the structure and function of these materials under working conditions. These efforts in my research group will be augmented by collaboration with computational catalysis experts in order to leverage theoretical tools critical to modern catalysis research. My research objectives are to enable the description of catalytic processes at the level of rate constants and to determine requisite active site properties in an effort to guide next generation materials synthesis and to effect improvements in reactivity, selectivity, and catalyst lifetime.

Graduate Studies (Purdue University; Advisors: Fabio H. Ribeiro and Rajamani Gounder)

PhD Dissertation Title: “Titration and Characterization of Lewis Acid Sites in Siliceous Oxides for the Catalysis of Oxygenates”

As chemical transformations of bio-derived oxygenates primarily occur in the liquid-phase, development of methods to promote favorable solvent-solid interactions is paramount to successful catalytic upgrading of renewable feedstocks. In my graduate studies, I gained expertise in materials synthesis, including oxide-supported metal nanoparticles and hydrothermal synthesis and post-synthetic modification of molecular sieves. I developed methods to quantify Lewis acidic active sites in metallosilicate molecular sieves via chemical titrations combined with measurement of infrared spectra. These techniques were instrumental in characterizing metallosilicates of various crystal topologies and in quantifying their active site evolution and degradation during reaction. These efforts allowed for comparison of glucose isomerization reaction rate constants between hydrophobic and hydrophilic catalysts and provided a clear demonstration of the impact of the polarity of the secondary environment around catalytic sites on reactivity in aqueous media, resulting in higher reaction rates over sites confined in hydrophobic pores.

Postdoctoral research (University of Minnesota; Advisor: Aditya Bhan)

Topic: “Selective oxidation of ethylene over promoted Ag catalysts”

My postdoctoral research focuses on the kinetics of ethylene epoxidation over a promoted silver catalyst. This catalyst system is employed to produce ~27 million tons of ethylene oxide per year, yet precise descriptions of the surface chemistry required for production of ethylene oxide at high selectivity (>85%) have not been developed. In industrial practice, co-fed alkyl chlorides deposit chlorine adatoms on Ag surfaces resulting in dramatic effects on the kinetics and increases in ethylene oxide selectivity, while co-fed alkanes remove chlorine and prevent catalyst poisoning. I have developed techniques for quantifying the chlorine coverage and determining mechanisms of chlorine deposition onto and removal from Ag surfaces, and correlated these changes in surface coverages to observed changes in ethylene oxide rate and selectivity. Through this experience, I have broadened my skillset to new classes of catalysts and reactions, and refined the mechanistic descriptions of catalytic processes occurring over industrially-employed, complex catalytic materials. My future research group will utilize strengths in materials synthesis, spectroscopic characterization techniques, and kinetic studies to guide rational catalyst design in applications critical to sustainable energy transformations, such as the conversion of multifunctional oxygenates to specialty chemicals and the control of toxic gas emissions.

Teaching Interests:

My interest in teaching, strengthened while designing and teaching a course during my undergraduate studies, motivated me to pursue both a graduate degree and a position in academia. Successful research in heterogeneous catalysis requires a thorough understanding of the core chemical engineering disciplines of transport, thermodynamics, and reaction engineering. The bulk of my teaching experience relates to the latter topic, as I served as a teaching assistant for undergraduate and graduate level reaction engineering courses as a graduate student. In these roles, I designed homework and exam exercises, created lesson plans for discussion sessions, gave guest lectures, and supervised laboratory sessions. I also served as the lead instructor for a section of a senior laboratory course at Purdue. I devoted significant effort to improving my teaching and preparing for a future in education by taking a graduate level engineering education course and completing the requirements for the Graduate Teaching Certificate from the Purdue Teaching Academy. These experiences, along with my mentorship of undergraduates and junior graduate students during my graduate and postdoctoral studies, have prepared me for successful teaching both in the laboratory and the classroom.