Structures and oxygen storage/release capacities of CexZr1-xO2: Effects of Zr content and preparation method

摘要

Ceria-zirconia solid solution has been prepared by the urea grind combustion and citric acid sol-gel methods for catalytic applications as oxygen storage/release materials in this study.The properties and oxygen storage/release capacities of samples with different Zr contents were characterized and evaluated by X-ray diffraction (XRD),N2 adsorption,scanning electron microscopy (SEM),Raman spectroscopy,and insitu CO-CO2 looping test.The results demonstrate that the samples prepared by two methods are all of excellent lattice [O] release/storage properties and maintain good long-term cycle stability.But the preparation method significantly impacts the homogeneity of samples related to their redox properties and the content of Zr over 20％,which greatly changed the properties of ceria-zirconia solid solutions and caused their changing of crystalline symmetry from cubic to tetragonal.The samples prepared by citric acid solgel method are of more homogeneous particle sizes and higher specific surface areas than that by urea grind combustion method,which is benefit to the oxygen release rather than oxygen storage.The bulk oxygen amount migrated to surface increases with the increasing Zr content,however,the amount of lattice oxygen migration decreases when Zr content is over 20％.When Zr content is 20％,the differences of storage/release capacities from two different preparation methods are reduced at high temperature in the long-term loop reaction.