CLEERS Teleconference: Prof. Mike Harold, University of Houston

Coupled Uptake and Conversion of NOx and Reductants on Pd/SSZ-13: Experiments and Modeling

Prof. Mike Harold
University of Houston

Abstract:

The trapping of NO in the presence of various reductants (CO, H2, C2H4, and C12H26) and H2O over a Pd/SSZ-13 washcoated Passive NOx Adsorber (PNA) monolith is examined through a combination of experiments, molecular and microkinetic analyses, and monolith reactor modeling. The commonalities and differences of NO uptake in the absence and presence of these reductants will be described. This includes the NO uptake and NO + NO2 release features. CO and C2H4 lead to enhanced NO uptake at lower temperature, generating CO2 and acetaldehyde, respectively. The release profiles shows evidence of multiple sorption sites on the dispersed Pd. We will present a microkinetic model that predicts the main features of the data and consistent with DFT predictions of energy barriers. We will also discuss recent findings of new trapping pathways through a combination of DFT (in collaboration with Lars Grabow) and targeted experiments along with SpaciMS measurements of integrated PNA, hydrocarbon trap (HCT), and oxidation catalyst (OC) functions.