An efficient Pt nanoparticle–ionic liquid system for the hydrodeoxygenation of bio-derived phenols under mild conditions

Platinum nanoparticles (NPs) were synthesized in situ in the ionic liquid (IL) [Emim]NTf₂ (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as well as in mixtures of [Emim]NTf₂ with a second IL, Lewis acid or Brønsted acid, but in the absence of additional stabilizers. The resulting NP/IL systems catalyze the hydrodeoxygenation of a phenol under mild conditions (60 °C, 1.0 MPa H₂), achieving full substrate conversion and a high deoxygenation rate (over 95%) to cyclohexane and cyclohexene. The combination of [Emim]NTf₂ and [Bmim]PF₆ results in the best catalytic performance. Also the transformation of other substituted phenols and dimers such as catechol, guaiacol and diphenyl ether was studied in the Pt NP/[Emim]NTf₂–[Bmim]PF₆ system and in most cases afforded cyclohexane in good yield.