(24b) Detailed Microkinetic Modeling for Emissions Oxidation From Engine Exhaust

The precious metal-based Diesel oxidation catalyst
(DOC) plays a fundamental role in reducing diesel fuel particulate matter and
other harmful emissions such as hydrocarbons (HC), carbon monoxide (CO) and nitric
oxides (NO_x), which have adverse impact on human health and
environment. Despite the extensive research on these catalysts, comprehensive
and predictive kinetic models for simultaneous prediction of multiple emissions
oxidation are lacking. In this work, a detailed elementary step microkinetic
model for oxidation of CO, NO, other nitrogen containing emissions (NH₃
and HCN) as well as toxic aldehydes (CH₂O) is developed. The
detailed mechanism development is carried out using several parameter
estimation techniques:  semi-empirical
Unity Bond Index-Quadratic Exponential Potential (UBI-QEP), Transition State Theory
(TST), quantum mechanical Density Functional Theory (DFT), and temperature
programmed experiments. Model predictions for catalytic oxidation of various
emission components will be discussed as a function of operating conditions
(see Figure for HCN oxidation).