(16i) Elucidating Diffusion, Adsorption, and Catalytic Processes in Oxide Materials

A conceptual and molecular level understanding of diffusion, adsorption, and catalytic processes forms the basis of most separations and catalytic processes. Herein, I present two case studies in which an improved understanding of physical and chemical rates processes in porous oxide materials enables the design of more effective materials: firstly, amine-modified mesoporous oxide materials for use in large-scale CO₂capture applications, and secondly, aliovalently doped non-reducible bulk oxides for alkane dehydrogenation.

A combination of advanced synthetic techniques, thorough physicochemical characterization, batch and breakthrough adsorption uptake measurements, and mass and heat transfer modeling was used to determine critical factors governing rates of CO₂ adsorption onto supported amine materials. At amine coverages significantly exceeding monolayer coverage, diffusion through the amine-polymer phase was identified as the key step limiting CO₂ adsorption rates. Heteroatom incorporation into the silica framework was used to ameliorate the adverse effect of amine loading on diffusion rates, presumably by resulting in a more open amine-polymer phase. The modified oxide materials thus developed represent effectiveadsorbents exhibiting a combination of both high equilibrium adsorption capacities and rapid diffusion through the amine-polymer network.

In my postdoctoral research work, kinetic and mechanistic details of the non-oxidative conversion of propane to propylene over non-reducible oxides were investigated. High surface area (127m²/g) bulk yttria doped zirconia materials were demonstrated to be highly active, selective, and regenerable propane dehydrogenation catalysts with propylene rates comparable to Pt and Cr-based catalysts used commercially. The kinetics and mechanism of alkane dehydrogenation over this new class of catalysts was studied, and methods for assessing the number of catalytic active sites under reaction conditions, developed. Ongoing and future research efforts will focus on extending this concept of highly selective acid-base pair mediated C-H activation on non-reducible oxides to other hydrocarbon conversion reactions.

Building off of my training in separations, catalysis, and industrial R&D, I envisage that my research program will emphasize a molecular level understanding of diffusion, adsorption, and reaction processes, with wide-ranging applications in chemical and energy conversion processes.

Teaching Interests:

Kinetics & Reaction Engineering, Transport Phenomena, Mass Transfer