Comparative study on the preparation, characterization and catalytic performances of 3DOM Ce-based materials for the combustion of diesel soot

Abstract

Three-dimensionally ordered macroporous (3DOM) praseodymium (Pr)-modified Ce-Zr solid solutions were successfully prepared by colloidal crystal templating method. They were characterized by the techniques of SEM, XRD, UV-Raman, N2 adsorption, and H2-TPR. 3DOM samples showed higher catalytic activities for soot combustion than corresponding disordered macroporous (DM) ones, which benefits from the enhanced contact efficiency between soot and ordered macroporous structure. In addition, the effects of Ce/Zr ratio on the phase composition and catalytic performances of Ce-Zr-O and Pr-Ce-Zr-O samples for soot oxidation were investigated. The results indicate that the phase compositions of Pr-modified ceria-zirconia solid solutions are similar to those of corresponding ceria-zirconia samples, and cubic–tetragonal phases coexist in the samples with moderate zirconia content, which is favorable for soot combustion. Furthermore, the effects of thermal and hydrothermal treatments on the catalytic properties for soot oxidation of 3DOM CeO2, Ce0.7Zr0.3O2 and Ce0.6Zr0.3Pr0.1O2 were comparatively studied. Compared with 3DOM bare CeO2, 3DOM Ce-Zr-based solid solutions, especially Pr-modified Ce-Zr solid solution Ce0.6Zr0.3Pr0.1O2 exhibited the highest thermal and hydrothermal stability because it possesses the lowest mobility of lattice oxygen among the three samples.