Synthesis of titanate nanotubes and their applications as Pd catalyst support

Abstract

In this research, titanate nanotubes and nanowires were synthesized by hydrothermal method from a spherical shape commercial TiO2. The effects of quenching, reaction temperature, and annealing on the formation and morphology of the titanate were investigated. Titanate nanotubes with high BET surface area were synthesized at 150ºC. The titanate nanotubes were transformed to titanate nanowires when the reaction temperature was increased to 200ºC. After annealing at 600 ºC, the titanate nanotubes transformed back into anatase TiO2 whereas annealing of the titanate nanowires resulted in metastable form TiO2 under similar conditions. The use of titanate nanotubes as Pd catalyst support resulted in higher catalytic performance in the liquid phase selective hydrogenation of 1-heptyne than the Pd catalysts supported on titanate nanowire and commercial titania. The titanate nanotubes supported Pd nanoparticles synthesized from reduction by solvent method exhibited higher conversion of 1-heptyne than those prepared by impregnation method. While the hydrogenation rate increased with increasing Pd dispersion, the selectivity to 1-heptene depended largely on the nature of TiO2 support and/or the interaction of Pd and titania support.