Abstract
This work reports on the redox behaviour of different ceria-praseodymia mixed oxides with two different chemical compositions (Ce/Pr molar ratios of 4:1 and 9:1), The samples consist of bulk oxides and ceria-supported samples with varying mixed oxide loading (equivalent to 7 or 12 mixed oxide layers). As revealed by x-ray diffraction and high-resolution electron microscopy, the samples consist of homogeneous fluorite-like mixed oxides. Their redox properties were characterized by means of the oxygen buffering capacity (OBC) technique, which quantitatively evaluates the capacity of the samples for attenuating fast oscillations of the oxygen partial pressure in the He stream flowing through the sample. These oscillations are induced by injecting with a high frequency pulses of oxygen into the inert gas stream. Although the XPS analyses performed on both a bulk and a supported sample showed Ce/Pr molar ratios very close to each other, the bulk mixed oxide exhibits significantly better OBC values. Also remarkable is that an ageing treatment at 1223 K improves the OBC response of the supported mixed oxides. In accordance with the XPS data, the enhancement of their redox properties runs parallel to an increase in the Ce/Pr surface ratio. These results are discussed in terms of the role played by the depth profile distribution of Pr in the different oxide samples.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
