CLEERS Teleconference: Mark Crocker, University of Kentucky

Palladium speciation in Pd-zeolite passive NOx adsorbers

Mark Crocker
University of Kentucky

Abstract:

Pd-exchanged zeolites have been extensively investigated for their performance as Passive NOx Adsorbers (PNAs), although much remains to be understood about the deactivation of these materials in the presence of exhaust gas components such as H2, H2O, and CO. In this study, in-situ diffuse reflectance IR spectroscopy was employed to identify the Pd speciation of both Pd-CHA and Pd-BEA zeolites after pretreatment under a range of conditions, CO adsorption being employed to visualize the Pd distribution. In parallel, NO adsorption and related reaction pathways are being studied by means of experimental methods and quantum chemical calculations. In this presentation, we report the results of these studies, focusing on the relationship between sample pre-treatment, Pd speciation, and NOx uptake and release.