Chemoselective hydrogenation of citral by Pt and Pt-Sn catalysts supported on TiO₂ nanoparticles and nanowires

Chemoselective hydrogenation of citral is studied over platinum catalyst supported on titanium dioxide nanoparticles and nanowires. The support is found to have considerable effect on both selectivity and activity. Because of the presence of weak basic sites on the nanowire support, the platinum catalyst shows significantly higher activity and better selectivity towards citronellal than that obtained by the catalyst based on TiO₂ nanoparticles having mainly medium strong basic sites. Furthermore, addition of tin promoter to the platinum catalyst decreases the initial rate of reaction and increases the selectivity towards unsaturated alcohols such as nerol and geraniol. The catalytic activity studies are complemented by chemical composition, surface adsorption and structural analyses of the applied catalyst materials assessed by the means of X-ray photoelectron spectroscopy, energy-dispersive X-ray analysis, temperature programmed reduction, H₂ and CO₂ desorption, CO chemisorption, electron microscopy and X-ray diffraction, respectively.