LAUSR

The morphology effect of Zr-doped CeO2 was studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant. In the present work, Zr-doped CeO2 nanorods exhibited the highest catalytic performance (yield of styrene oxide and TOF value) followed by nanoparticles and nanocubes. For the Zr-doped CeO2 nanorods, the apparent activation energy is 56.3 kJ/mol, which is much lower than the values of catalysts supported on nanoparticles and nanocubes (73.3 and 93.4 kJ/mol). The high resolution transmission electron microscopy results indicated that (1 0 0) and (1 1 0) crystal planes are predominantly exposed for Zr-doped CeO2 nanorods while (1 0 0) and (1 1 1) for nanocubes, (1 1 1) for nanoparticles. The remarkably increased catalytic activity of the Zr-doped CeO2 nanorods is mainly attributed to the higher percentage of Ce3+ species and more oxygen vacancies, which are associated with their exposed (1 0 0) and (1 1 0) crystal planes. Furthermore, recycling studies proved that the heterogeneous Zr-doped CeO2 nanorods did not lose its initial high catalytic activity after five successive recycles.