Degree

Doctor of Philosophy (PhD)

Department

The Gordon A. and Mary Cain Department of Chemical Engineering

Document Type

Dissertation

Abstract

With the rapid depletion of the U.S. energy resources coupled with population growth, heat management technologies must be improved to sustain our quality of life. Precisely, in catalysis, it is estimated that only ~50% of the energy supplied to the reactor is used for product conversion due to dissipation losses. Among the emerging technologies with a promising reduction in heat losses is induction heating, offering targeted heat delivery with magnetic nanoparticles. Under alternating magnetic fields (AMF), these nanoparticles can absorb the energy from Radio-Frequency (RF) fields and dissipate it as heat on the nanoparticle surface. This in situ heat generation has the added advantage of reducing risks associated with high-temperature reactor setups, given that the solution would be hotter near the nanoparticle surface and colder on the reactor walls.

The successful integration of induction heating in industrial processes requires coupling induction heating and catalytic properties, and this combination has proven to be challenging given that the most suitable alternatives include magnetic materials. Nonetheless, this work unveils the opportunities for catalyst tunability by changing the structure of Fe3O4 nanoparticles, which are well known in the literature. Therefore, the complexity of coupling multiple properties can be reduced by starting from a good RF susceptor and implementing systematic changes to study their effect on induction heating catalysis. Modifications on the nanoparticle surface chemistry, size, morphology, and introduction of dopants are the parameters studied in this dissertation, offering a thorough description of the structure-property relationships in Fe3O4 nanoparticles. These nanostructures are studied in the context of colloidal decomposition routes, which have proven to allow remarkable control over particle size and morphology, producing particles in the hysteresis losses regime (< 20 nm), generating more energy than their bulk materials. However, structural control often involves the use of surfactants, which sterically hinder the catalytic adsorption sites. Therefore, surface chemistry is evaluated without compromising structural integrity to maintain magnetic properties. Lastly, a luminescent probe strategy to determine the temperature near the nanoparticle surface is provided to reduce temperature inaccuracies, allowing the possibility to drive chemical reactions at apparent-lower temperatures, ultimately impacting heat management issues.

Committee Chair

Dorman, James A.

Available for download on Thursday, August 18, 2022

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