Abstract

Platinum (Pt) and palladium (Pd) nanoparticles (NPs) supported on titanate nanotubes (TiNTs) Pt@TiNT and Pd@TiNT were prepared for the liquid-phase hydrogenation of nitroarenes at 25 degrees C Initially, TiNT was modified with 3-aminopropyl-trimethoxysilane to provide a strong anchoring site to trap the Pt and Pd NPs, which prevent the metal NPs from leaching. As-prepared 1 wt% of metal loading catalysts were characterized by transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms, X-ray diffraction, and X-ray photoelectron spectroscopy measurements. The TEM images confirmed that the Pt (1.70 +/- 0.19 nm) and Pd (2.80 +/- 0.43 nm) NPs were mainly confined into the channel of TiNTs. Both catalysts exhibited excellent catalytic performances for the reduction of nitrobenzene as a model compound under mild reaction conditions. The superior catalytic activity for the hydrogenation of nitroarenes is attributed to the small size of the Pt and Pd NPs. However, the operational stability showed that Pt@TiNT retained its catalytic performance after 10 cycles, while Pd@TiNT suffered deactivation by metal sintering after the sixth cycle. The Pt@TiNT system exhibited high efficiency in the hydrogenation of different substituted nitroarenes of pharmaceuticals interest, and it showed an excellent activity and selectivity toward the production of desired substituted anilines.