Heterogen Catalysis in Sustainable Green Solvent: Alkenes Hydrogenation With New Silica Immobilized Palladium Complex Containing S,o-Chelating Ligand

Pd(II) complex containing S,O-chelating ligand was immobilized on surface of the amine functionalized silica support in scCO 2 media. Silica-based catalyst ( SiO 2 -ThiophPd(II)) were characterized by IR, SEM, XRF, and BET analyses. The catalytic activity of the immobilized catalyst in hydrogenation reactions of alkenes has been compared with the homogeneous counterpart. SiO 2 -ThiophPd(II) catalyst showed good activity and reusability than homogeneous system. The best conversion in styrene hydrogenation was obtained with TOF value as 5871 h -1 at 370 K, 10 bar H 2 and 1500 psi total pressure. Especially, while homogeneous counterpart has not activity in cyclohexene hydrogenation, it has been provided 100% cyclohexane conversion with the immobilized catalyst. It has also been found that the catalyst can be reused at least ten times without significant loss of activity in the styrene hydrogenation