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).