Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene over Pt-Bi/TiO2 catalysts

Abstract

The selective hydrogenation of a molecule containing several unsaturated groups is a very important issue and has attracted much more attention in the chemical synthesis. Herein, a highly selective catalyst of Pt-Bi/TiO2 was first time developed for the hydrogenation of 3-nitrostyrene (NS) to 3-aminostyrene (AS), with it an excellent selectivity to AS of 96% was achieved at the complete conversion. The influence of Bi on the catalytic performance was well discussed by using X-ray diffraction (XRD), transmission electronic microscopy (TEM), CO pulse chemisorption, hydrogen temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance Fourier transform infrared (DRFTIR) spectroscopy of adsorbed CO, and thermo gravimetric analysis (TGA) and experiment data. With increasing Bi loading, Bi-rich surface was formed, and the terraces sites of Pt disappeared as it transferred to the low coordinated Pt gradually. Thus, high selectivity of AS was obtained over Pt-Bi/TiO2 for the hydrogenation of AS to 3-ethylaniline (EA) was lowered.