Enhanced Catalytic Capability through Controlled Reaction Environments: A Merger of Solvent Effects and Rational Catalyst Design

Research Interests:

  Satisfying the demand for energy and chemicals via efficient and sustainable utilization of carbon resources is the defining challenge of the 21^st century. Catalysis has the potential to satisfy these demands by enabling the use of non-traditional resources and enhancing the efficiency of those currently consumed. Essential to achieving this goal is the ability to predict and design new catalytic materials, which requires a fundamental understanding of catalytic surfaces and the associated chemical landscape.

My PhD research experience focused on understanding the impact of water on carbonyl reduction over supported Ru catalysts, which is one of the key chemistries in catalytic biomass upgrading and thought to be strongly modified by electronic effects. Through rigorous microkinetic modelling, a quantitative understanding was developed of the mechanism by which ketones are reduced to alcohols on a Ru surface. The microkinetic model then provided better understanding of the effects of water on the rate of hydrogenation; water increases the rate of hydrogenation through a preferential stabilization of the kinetically relevant transition state on the Ru surface via hydrogen bonding. This was confirmed by comparison with alkanes, which are incapable of participating in hydrogen bonding and showed no promotional effect on the rate.

My postdoctoral research at the University of Minnesota focused on the production of renewable chemicals (diolefins) from lignocellulosic biomass. Diolefins are key monomers in the manufacture of synthetic rubber for technologies such as renewable car tires. Saturated furans, derived from sugars, are converted to diolefins through an acid catalyzed mechanism called ‘dehydra-decyclization’ that was discovered as part of my research. This was particularly exemplified with tetrahydrofuran, where near quantitative yields to butadiene were achieved using an all-silica zeolite impregnated with phosphoric acid. The production of isoprene from 3-methyltetrahydrofuran was similarly demonstrated, which was optimized through experimental high throughput catalytic screening. The technology provides a renewable route to diolefins which serve as vital building blocks for most polymer products in the rubber industry.

My future research direction lies at the intersection of catalytic descriptors, hybrid reaction environments and data-driven discovery. Much of catalyst discovery has been guided through heuristics and inherited knowledge, where an ad-hoc approach has been adopted for selecting better catalysts. Computational efforts provide a guided approach to catalyst design, with volcano plots based on the Sabatier principle as a prominent example. A significant push is yet to be made with experiments, where large kinetic data sets of information will be required. Beyond simply understanding catalytic functionality in traditional reaction environments, a need exists to understand a catalyst’s behavior at varying reaction conditions. The nature of the solvent environment in which a catalyst is placed is one such example, which has been shown to drastically affect the rates of reaction. Leveraging solvent effects has found beneficial applications in acid catalyzed dehydrations, metal catalyzed reductions, selective oxidation and multiple other catalytic systems. A solvent based approach to tuning catalyst performance becomes especially attractive in areas such as catalytic biomass upgrading, where the inherently high water content of biomass can be utilized. Through a predictive understanding of how a solvent environment can affect a catalytic surface, reaction conditions can be better tailored to maximize desired catalytic transformations. Teaching Interests:

Research can inspire teaching. As part of my graduate degree program, I was involved in undergraduate course development, where I designed experiments, equipment and course material for undergraduate teaching labs. I designed and constructed an experiment where senior year students operated a vapor phase packed bed reactor, studying the kinetics of isopropanol dehydration over solid acid catalysts. I also designed an experiment to demonstrate the concept of residence time distribution (RTD) in reactors, where students measured and applied RTD fundamentals to a series of continuously stirred tank reactors using step tracers.  I also served as a teaching assistant for graduate level mathematics for chemical, biomedical and mechanical engineering students. While I would especially enjoy teaching reaction engineering courses, both at the graduate and undergraduate level, I am comfortable teaching many of the core chemical engineering courses (Mass & Energy Balances, Heat & Mass transfer and thermodynamics) as well as upper-level courses including Process Design, Unit Operations and Product Design.