The Pr promotion effect on oxygen storage capacity of Ce–Pr oxides studied using a TAP reactor

The oxygen storage capacity including OSC, OSCC and dynamic OSC was measured for Ce–Pr oxides using a temporal analysis of products (TAP) reactor system. The exact features of reduction and re-oxidation were obtained by accurately measuring the uptake of CO and O, and the production of CO 2 . It was found that the reduction temperature of Ce–Pr oxides was lowered 50–100 °C in comparison to that of CeO 2 . The substitution of cerium by praseodymium in the Ce 1− x Pr x O 2− δ oxides enhanced both OSC and OSCC. However, OSCC was much influenced by the increase of praseodymium content more than OSC. It was interpreted that the addition of Pr significantly increased the amount of oxygen migrating from bulk to surface while the migration rate of bulk oxygen was slightly accelerated. On the basis of analyses of the Ce 3d, Pr 3d and O 1s X-ray photoelectron spectra, the promotion effect of Pr on oxygen storage capacity could be attributed to the Ce 4+ /Ce 3+ , Pr 4+ /Pr 3+ redox behaviour and the enrichment of oxygen vacancies in Ce 1− x Pr x O 2− δ .