Nanorods-assembled CeVO_4 hollow spheres as active catalyst for oxidative dehydrogenation of propane

摘要

CeVO_4 hollow sphere nanostructures have been prepared by a simple hydrothermal synthesis method. HRTEM investigation indicates that the CeVO_4 hollow spheres are assembled by small single crystal nanorods. Through a plus post annealing treatment at 500℃, the CeVO_4 hollow spheres have more Ce4* species (Ce~(4+)/(Ce~(4+) + Ce~(3+)) is ca. 5%) in the surface compared with the as-prepared sample (ca. 1%) based on the XPS results. No CeO2 and V_2O_5 phases were examined by both XRD and Raman spectroscopy, which indicates that Ce~(3+)-Ce~(4+)/V~(5+)-V~(4+) coexist in the annealed CeVO_4 hollow spheres, confirmed by the existence of V4* detected by XPS. At 500℃, the nanorods assembled CeVO_4 hollow spheres exhibits a rather very high selectivity (ca. 70%) for propylene in oxidative dehydrogenation (ODH) reaction of propane. The presence of Ce4*, which induces additional V4* in these hollow sphere nanostructures, is critical for the enhancement of selectivity of the catalyst.