Novel advanced channel reactor for spatio-temporal activity and catalyst state correlations applied for the reduction of NO by CO over Pt/Al₂O₃

The correlation of space- and time-resolved measurements of catalytic activity with catalyst state is an invaluable tool to advance the understanding and development of complex catalytic systems under conditions relevant to technical applications. Such an approach is employed here to investigate the catalytic deactivation in the reduction of NO by CO over Pt/Al₂O₃ on freshly reduced catalysts in a channel reactor and at concentrations typical for emission control. Planar laser-induced fluorescence (PLIF) is used to visualize the 2D concentration profiles and to derive space- and time-resolved NO conversion rates for different CO/NO ratios, temperatures and mass flow rates. The changes in catalytic activity are correlated with temporal and spatial changes in oxidation state determined by <i>operando</i> X-ray absorption spectroscopy (XAS) under the same conditions. The time scales of the changes in catalytic activity depend not only on the stoichiometry and temperature, but also on the position along the catalyst channel and differ significantly from the temporal changes of the oxidation state. ... mehrThe different time scales are discussed in the context of the known CO poisoning as well as the formation and storage of isocyanate on the support. Isocyanate formation temporarily counteracting CO poisoning could explain the differences in the observed time scales under different reaction conditions and at different locations on the catalyst.