Real-time observation of the effect of oxygen storage materials on Pd-based three-way catalysts under ideal automobile exhaust conditions: an operando study

Abstract

The dynamic behavior of Pd species and the CeO₂ support of 1 wt% Pd/Al₂O₃ and Pd/CeO₂ catalysts during three-way catalysis was examined in real time with operando multi-probe analysis using a micro gas chromatograph, a NO_x meter, and a quadrupole mass spectrometer and time-resolved quick X-ray absorption spectroscopy (XAS) measurements. With additional ex situ NO pulse measurement, the results demonstrated the effect of oxygen storage materials under ideal automobile exhaust conditions, which can be summarized into a well-known anchoring effect of CeO₂ on active metal species, an oxygen storage/release effect to maintain near stoichiometric conditions on the catalyst surface, NO reduction ability of CeO₂ itself, and storage/release of carbonaceous species on/from CeO₂.