A global description of DOC kinetics for catalysts with different platinum loadings and aging status

Global kinetic models usually require a recalibration in case of catalyst aging or changes in the precious metal loading. In this contribution the lean oxidation kinetics of CO, propene and NO for five (Pt-γ-Al2O3) diesel oxidation catalysts (DOCs) with different platinum loadings and stages of aging are determined from isothermal steady-state experiments. HR-REM shows that for all catalysts the platinum particles have diameters larger than 8 nm, so that the catalysts are in the structure insensitive regime. It will be confirmed that in this case the catalytic activity is only proportional to the catalytically active surface which can be determined easily by CO-chemisorption experiments. In order to model the CO- and propene-oxidation kinetics for differently aged and platinum loaded catalyst, only one parameter, the catalytically active surface, has to be changed in the global kinetic models. The same is true for NO oxidation at higher temperatures, where platinum stays in an oxidized state.

Figure optionsDownload as PowerPoint slideResearch highlights▶ DOC kinetics for catalysts with different platinum loadings and aging status. ▶ Adaption of kinetics by scaling reaction rate with catalytically active surface. ▶ Catalytically active surface can be determined by light-off measurements.