Photocatalytic hydrogenation of cyclohexene through H 2O as a source of H 2 by Pt/CdS/RuO 2 semiconductor particulate system catalysed by K[Ru(H—EDTA)Cl]2H 2O

Abstract

Hydrogenation of cyclohexene in aqueous ethanolic solutions (80:20 ethanol-water) of K[Ru(H—EDTA)Cl]2H 2O occurs during illumination of a semiconducting Pt/CdS/RuO 2 particulate system under ambient conditions. Cyclohexane is formed at a rate equal to 23μ1h −1 (turnover rate = 8.5 mol cyclohexane per mol catalyst per hour) and a total of 7–8% of cyclohexene is hydrogenated in about 12 h irradiation time. A mechanism for the hydro-genation of cyclohexene is proposed incorporating metal-alkene and mixed metal-alkene-hydride intermediates. The formation of these intermediates is amply supported by spectroscopic studies of photolysed reaction mixture. Hydrogen for the hydrogenation of cyclohexene is obtained by the photosplitting of H 2O.