Oxidative carbonylation of phenol with a Pd-O/CeO2-nanotube catalyst

CeO2 nanotubes (CeO2-NT) were synthesized using carbon nanotubes as template by a liquid phase deposition and hydrothermal method. X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption were used to characterize the CeO2-NT. The wall of CeO2-NT was composed of small interconnected nanocrystallites ranging from 4 to 9 nm in size. The specific surface area of CeO2-NT was 108.8 m2/g with an outer diameter of 25 nm and length > 300 nm. Supported Pd catalyst, Pd-O/CeO2-NT, was prepared using CeO2-NT as the support. Temperature-programmed reduction analysis showed that the surface oxygen on Pd-O/CeO2-NT could be reduced at low temperature, therefore it showed high activity in the reaction. Pd-O/CeO2-NT was used as the catalyst for the oxidative carbonylation of phenol. It has better activity and DPC selectivity than Pd-O/CeO2-P, which was prepared by supporting Pd on zero dimensional CeO2 particles. Under the optimized conditions, phenol conversion was 67.7% with 93.3% DPC selectivity with Pd-O/CeO2-NT. However, its catalytic activity decreased when the catalyst was used for the second time. This was attributed to the destruction of the tubular structure of Pd-O/CeO2-NT and Pd leaching during the reaction.

Graphical AbstractCeO2 nanotubes (CeO2-NT) as the support for a Pd catalyst, Pd-O/CeO2-NT, gave high phenol conversion with high dipenyl carbonate selectivity in the oxidative carbonylation of phenol.Figure optionsDownload as PowerPoint slide