281962 Simplifying the Complex Chemistry of Energy Conversion
Due to their high energy density and compatibility with existing infrastructure, hydrocarbon fuels will remain the principal energy storage medium for the foreseeable future. Although petroleum will continue to be the main fuel source, fuels derived from other materials – such as biomass, tar sands, and shale – will become major components. At the same time, increased efficiency and emissions regulations will impose new restrictions on engine and emissions control technology. Consequently, both the composition of and the requirements for next generation fuels are going to change dramatically in the coming decades. As the global demand for these fuels continues to increase, the development of sustainable technologies for the production and consumption of these fuels becomes increasingly urgent. In order to make these technologies commercially viable, we must advance our understanding of how the chemical bonds in these fuels are manipulated at the atomic level.
Short-contact time partial oxidation, flash pyrolysis, oxidative coupling, hydrothermal reforming, and Fischer-Tropsch can be used to synthesize fuels from diverse materials such as bio-mass, natural gas, and synthesis gas. Advanced conversion technologies such as catalytic combustion and solid oxide fuel cells could generate power with increased efficiency. Although the individual processes are quite different, each process involves temperatures and pressures that are high enough that the surface and gas-phase chemistry are coupled.
The challenge to developing these technologies is the staggering complexity of energy conversion. Alkane activation typically requires high temperatures and high pressures. Under these conditions, the heterogeneous chemistry on the catalyst surface is coupled with homogeneous chemistry in the gas phase. An accurate description of the chemical kinetics involves hundreds of species and thousands of elementary reactions, even for a species as light as propane. A detailed description of the coupling between homogeneous and heterogeneous chemistry requires quantitative descriptions for convective and diffusive fluxes in the gas phase and adsorption and desorption at the surface. This coupling is further influenced by the dynamic nature of the catalyst itself, which can undergo electronic and structural changes in response to the gas-phase chemical potential.
My research will help to elucidate the complex chemistry of energy conversion. I will combine experimental techniques with a suite of computational methods to create quantitative, predictive models for homogeneous/heterogeneous coupled systems. The benefit of detailed chemical kinetic mechanisms is two-fold. At a qualitatively level, they disentangle the layers of confusing phenomena, thereby providing engineers with insight into what is really going on at the atomic level. At a quantitative level, they make accurate predictions of future trends, thereby saving time and money. The techniques I am developing will provide fundamental insight into how fuels are manipulated at the atomic level, and they will accelerate technological breakthroughs in sustainable energy conversion.