Liquid-phase hydrogenation of phenylacetylene over the nano-sized Pd/TiO2 catalysts.

Abstract

Understanding the mechanisms of metal-support interaction and/or adhesion and growth of the metal particles is important not only in the field of catalysis but also the design of advanced nanostructure materials. In the present work, the strong metal-support interaction (SMSI) effect occurred on the Pd/TiO2 catalysts synthesized by the sonochemical method when reduced at 500 degrees C whereas the ones prepared by the conventional impregnation resulted in sintering of Pd0 particles instead. The presence of SMSI was correlated to the amount of oxygen vacancies or Ti3+ defective sites. Smaller Pd0 particles with more uniform size distribution on the sonochemical-derived catalysts may promote hydrogen spillover from Pd0 surface to TiO2 support so that the reduction of Ti4+ to Ti3+ occurred, resulting in the SMSI. As a consequence, the catalysts exhibited improved catalytic performances in the liquid-phase selective hydrogenation of phenylacetylene to styrene.