Understanding the effects of solvents on the hydrogenation of toluene over supported Pd and Ru catalysts

Abstract The effects of solvents (n-hexane, isopropanol (IPA), tetrahydrofuran (THF) and methanol) on the hydrogenation of toluene over the Pd/SiO2 and Ru/SiO2 catalysts were studied. Microcalorimetric adsorption and IR spectroscopy were employed to understand the effects. It was found that n-hexane adsorbed weakly on the catalysts and thus affected less the hydrogenation of toluene, while THF and methanol adsorbed strongly on the catalysts and inhibited the activity of hydrogenation of toluene significantly. IPA also adsorbed strongly on the catalysts, but it exhibited a hydrogen transfer effect on the surfaces that promoted the conversion of toluene.