Enhanced hydrogenation activity of nano-sized Pd–Ni bimetal particles on Ti-containing mesoporous silica prepared by a photo-assisted deposition method

Abstract

A facile photo-assisted deposition (PAD) for the synthesis of highly dispersed and small Pd–Ni bimetal nanoparticles with a narrow size distribution has been developed by combining mesoporous silica materials including a single-site Ti-oxide moiety (Ti-HMS) as a promising photo-responsive catalyst support. Under UV-light irradiation, both Pd and Ni precursors can be deposited directly on the photo-excited tetrahedrally coordinated Ti-oxide moiety within the silica frameworks, and subsequently reduced with H₂ to generate the nano-sized Pd–Ni bimetal particles. Compared with individual Pd or Ni-loaded Ti-HMS (Pd or Ni/Ti-HMS) prepared by PAD and PdNi/Ti-HMS prepared by the conventional impregnation (Imp) technique, the PdNi/Ti-HMS prepared by PAD showed a strong synergistic effect in the catalytic hydrogenation of nitrobenzene (NB) to aminobenzene (AB). It was also found that the hydrogenation activity reached a maximum at the molar ratio of Ni/Pd = 1.5, while further increases in Ni loading amount gradually decreased the catalytic activity.