(3ax) Homogeneous/Heterogeneous Chemistry In Energy Conversion

Hydrocarbon fuels will remain the energy storage medium of choice for the foreseeable future.  As the global demand for these fuels increases, sustainable technologies for both the production and consumption of these fuels will become critical.  A suit of reforming processes can be used to synthesize liquid fuels from various feed stocks, such as biomass or natural gas.  Examples of intermediate processes include short-contact time partial oxidation, oxidative coupling, hydrothermal reforming, and Fischer-Tropsch synthesis.  Advanced conversion technologies – such as homogeneous-charge compression ignition, catalytic combustion, and solid oxide fuel cells – could generate power with increased efficiency.

            In order to make these technologies both sustainable and commercially viable, we must understand how the chemical bonds in these fuels are manipulated at the atomic level.  Unfortunately, the chemistry of energy conversion is staggeringly complex.  Most of these technologies involve high temperatures and high pressures.  Under these conditions, homogeneous gas-phase chemistry is coupled with heterogeneous surface-phase chemistry.  A detailed mechanism for combustion of comparatively small hydrocarbons requires hundreds of species and thousands of reactions, and the inclusion of surface chemistry dramatically increases the complexity.

            My research will help to elucidate the complex chemistry of energy conversion.  I will combine various computational methods with experimental techniques to create and validate kinetic mechanisms in homogeneous/heterogeneous coupled systems.  Gas-phase mechanisms will be generated using an automatic reaction mechanism generator, RMG.  Thermodynamically consistent surface mechanisms will be generated using scaling relationships, BEP relations, and other methods.  Spatial profile reactors will provide experimental data under industrially relevant conditions.  The simplified flow field, wide range of operating conditions, and sub-mm resolution of these instruments make them ideal candidates for evaluating microkinetic models.  Sensitivity, flux, and reaction-path analyses will highlight which minima and saddle points on a potential energy surface are most important, and these stationary points will be refined with computational quantum chemistry (e.g. DFT) and statistical mechanics.  New experiments will be performed to highlight certain reaction channels.  This process is iterated until the mechanism is suitably accurate.  Finally, mechanism reduction techniques will be applied to create a skeletal mechanism that can be combined with CFD codes for industrial applications.