Author's School

School of Engineering & Applied Science

Author's Department/Program

Energy, Environmental and Chemical Engineering

Language

English (en)

Date of Award

Summer 9-1-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Cynthia Lo

Abstract

Conversion of carbon-containing compounds, especially C1 compounds such as carbon dioxide and methane, to valuable chemicals and fuels will hopefully address concerns over decreasing supplies of fossil fuels and mitigate the eects of greenhouse gas emissions on global climate change. Many challenges, however, remain to be addressed before these technologies may be adopted on an industrial scale. Chiefly, catalysts must be developed to activate carbon-containing compounds from their thermodynamically stable ground states, using hydrogen, electrons, or heat as energy sources. We chose as model catalytic systems: 1) Metathesis of ethene and 2-butene; 2) Methane dehydrogenation and carbon dioxide hydrogenation. We developed three computational methodologies to study these processes across a range of length and time scales. First, we investigated how electronic structure affects the properties and reactivity of these catalyst systems; by computing the partial electronic density of states, electronic localization function, and excess spin density, we showed how redox supports, such as ceria, promote electron transfer reactions. We applied this to the studies of methane activation and carbon dioxide activation. Second, we developed a non-equilibrium thermodynamics approach to calculate energies of activation at nite temperatures, based on the Bronsted-Evans-Polanyi principle and the Nudged Elastic Band method. Third, we developed an approach to numerically compute heat capacities and other thermodynamic properties on extended catalytic systems that are comparable in accuracy and precision to methods that have been well-developed for gas-phase molecules. We applied these to the studies of metathesis propagation and carbon dioxide hydrogenation. We gained mechanistic, thermodynamic, and kinetic insight into the elementary steps that comprise larger reaction networks of interest to the broader catalysis community. Ultimately, these theoretical and computational predictions can be used to guide experimental design, synthesis, and characterization of new catalyst systems.

DOI

https://doi.org/10.7936/K7XG9P78

Comments

Permanent URL: http://dx.doi.org/10.7936/K7XG9P78

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