A study on H2-TPR of Pt/Ce0.27Zr0.73O2 and Pt/Ce0.27Zr0.70La0.03Ox for soot oxidation

Pt/Ce0.27Zr0.73O2 and Pt/Ce0.27Zr0.70La0.03Ox catalysts, prepared by co-precipitation and impregnation methods, were thermally treated at different temperatures for 10 h and then characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), thermogravimetric analysis (TGA) and soot temperature-programmed oxidation (soot-TPO). Due to thermal effect on the structural and textural properties, the aged catalysts show increased reduction temperatures. But, interestingly, more H2 consumption is detected, which would be ascribed to the increased mobility of bulk oxygen and surface lattice oxygen. The promoting and synergistic roles of Pt in H2-TPR are discussed and it reveals that the sintering and encapsulation of Pt would weaken the H2 spillover mechanism and the addition of La is beneficial to stabilize the synergistic effect between Pt and Ce. On the other hand, a humble role of Pt on promoting soot oxidation activity is found in this study. Not all oxygen species available in H2-TPR can be used for soot oxidation. The deactivation of the aged catalysts is closely related to the reduction temperature.