Mechanism Understanding for NOx storage, release and reduction on Pt doped Ceria based Catalysts

Due to strengthening legislations on exhaust emissions of lean-burn gasoline and diesel engines, there is a need for further optimisation of existing emission after-treatment catalytic converters for automotive applications. New regulations focus primarily on NOx abatement at low temperature.High surface area ceria is successfully employed as an excellent support of PGMs in commercial catalytic LNT systems for automotive emission control. Platinum supported on ceria shows enhanced NOx storage at low temperatures, together with improved hydrocarbons light-offs. Ceria also possesses a high OSC with unique redox properties that can be further enhanced using dopants. The main function of these dopants is to allow the catalyst to function outside of the normal working temperature range and widen the operating conditions to increase catalyst efficiency. To this end, Samarium was selected due to its reported effect on Pt reducibility and the platinum-ceria interaction, to allow greater activation during rich purge. Sm doped catalysts (10 wt.%) were synthesised on a range of ceriabased catalysts with increasing loadings of Pt (0-1 wt.%). The objective of this study was to investigate the effect of the dopant on the performance of the different catalysts, and, to understand morphological changes on the surface.