Pd catalyst supported on CeO 2 nanotubes with enhanced structural stability toward oxidative carbonylation of phenol.

Ordered CeO 2 nanotubes (CeO 2 -T) were prepared via a hydrothermal synthesis process using the triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide (P123) as a morphology control agent. CeO 2 -T characterization demonstrated the formation of single crystal structures having lengths between 1-3 μm and diameters < 100 nm. A supported Pd catalyst (Pd/CeO 2 -T) was also prepared through hydrothermal means. H 2 -temperature reduction profile and Raman spectroscopy analyses showed that the oxygen vacancies on the CeO 2 surface increased and the reduction temperature of the surface oxygen decreased after Pd loading onto CeO 2 -T. Pd/CeO 2 -T was employed as a catalyst toward the oxidative carbonylation of phenol and the reaction conditions were optimized. Phenol conversion was 53.2% with 96.7% selectivity to diphenyl carbonate under optimal conditions. The integrity of the tubular CeO 2 structure was maintained after the catalyst was recycled, however, both activity and selectivity significantly decreased, which was mainly attributed to the Pd active component significantly leaching during the reaction.