Hydrogenation of Carbon Dioxide to C2–C4 Hydrocarbons Catalyzed by Pd(PtBu3)2–FeCl2 with Ionic Liquid as Cocatalyst

Abstract

Direct hydrogenation of CO2 to C2+ hydrocarbons is very interesting, but achieving this transformation below 200 °C is challenging and seldom reported. Herein, a homogeneous catalytic system was developed composed of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6 ]), Pd(PtBu3 )2 , FeCl2 , and the ligand 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) for hydrogenation of CO2 under mild conditions, which resulted in C2 -C4 hydrocarbons in selectivities up to 98.3 C-mol % at 180 °C. The combination of [BMIm][PF6 ]) with Xantphos endowed the Pd-Fe catalysts with the ability of activating CO2 and H2 simultaneously via [HPd(PtBu3 )(BMIm-COO)(BMIm)(PF6 )Fe]+ species, thus catalyzing the formation of C2 -C4 hydrocarbons through CO2 hydrogenation. In addition, this catalytic system is stable and recyclable, which may have promising applications.