Palladium supported on hierarchically macro–mesoporous titania for styrene hydrogenation

Hierarchically macro–mesoporous titania was synthesized by the simple dropwise addition of tetrabutyl titanate to an ammonia solution in the absence of surfactant molecules, and then calcined at different temperatures. The as-prepared titania was characterized by X-ray diffraction, N2 adsorption–desorption analysis and scanning electron microscopy. The results showed that the hierarchically marcro–mesoporous structure of the titania was well preserved after calcination at 650 °C, indicating high thermal stability. The 500 °C calcined titania with the hierarchically bimodal pore network was impregnated with 0.5 wt.% of palladium and compared with 0.5 wt.% Pd/TiO2 catalyst without such macrochannels. The novel macro–mesostructured Pd/TiO2 catalyst exhibited higher catalytic activity for styrene hydrogenation due to the lower diffusion resistance of species inside the catalyst caused by the hierarchically macro–mesoporous bimodal structure.