Morphology effect of Ru/CeO2 catalysts for the catalytic combustion of chlorobenzene

• Highly dispersed Ru catalysts on ceria nanoparticles with different morphologies were prepared.
• The relaxing Ce–O bond has a strong interaction with Ru species, leading to the formation of Ru–O–Ce.
• Ru/CeO2-rod possesses much more oxygen vacancies and Ru–O–Ce than other Ru/CeO2 samples.
• Ru/CeO2-rod exhibits high stable activity for chlorobenzene oxidative decomposition.
• High stable activity is related to more Ru–O–Ce bond, high oxygen mobility and content of Ru4+.

The present work elucidated the morphology and crystal-plane effects of nanoscale ceria on the activity of Ru/CeO2 catalysts toward catalytic combustion of chlorobenzene taken as a model of chlorinated aromatic hydrocarbons (CAHs). CeO2 nanorods (CeO2-r), nanocubes (CeO2-c) and nano-octahedra (CeO2-o) (enclosed by {110} and {100}, {100} and {111}, respectively) as supports, were prepared by wet impregnation. The status and structure of Ru species is quite dependent on the enclosed various facets. Ru/CeO2-r possesses much more Ru4+, oxygen vacancies and Ru–O–Ce bonds than Ru/CeO2-c and Ru/CeO2-o, indicating that there is a stronger interaction between Ru and CeO2-r. The surface oxygen mobility and reducibility follow the order of Ru/CeO2-r > Ru/CeO2-c > Ru/CeO2-o. The activity test of chlorobenzene oxidation shows that Ru/CeO2-r is more active than that of Ru/CeO2-c and Ru/CeO2-o, with T10% and T90% of 160 and 280 °C, respectively, which can be related to a larger number of Ru–O–Ce bonds, higher content of Ru4+ and surface oxygen mobility and reducibility. These results confirm that the activity of Ru/CeO2 catalysts for CB oxidation is greatly affected by CeO2 shape/crystal plane.

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