Fast and Sustainable Co2 Conversion to Propylene Carbonate Using Fluoroalcohol-Based Bifunctional Ionic Liquids: Insights from Experiments and Theoretical Simulations

Abstract

We report on the metal-free and rapid catalytic conversion of CO2 into cyclic carbonates under solventless conditions utilizing novel bifunctional fluoroalcohol-based ionic liquids (FBILs) as catalsyts. In the presence of 2.5 mol% 4-(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl) phenyl trimethylammonium iodide (FBIL-1), under 0.1 MPa and 90 °C, excellent yield of propylene carbonate(>95%) was achieved in 1h, which significantly shortens the reaction time, compared with the conventional catalysts. DFT calculations showed that FBILs, with unique features of fluorine-substituted hydroxyl groups, are more likely to form hydrogen bonds with epoxides than ionic liquids (ILs) lacking such groups. This feature helps lower the activation energy of the epoxide ring-opening reaction, thereby enabling rapid CO2 fixation in cyclic carbonates. Besides high catalytic efficiency, these FBILs have the characteristics of a facile synthesis route and easy post-reaction recovery.

Keywords: Fluoroalcohol-based bifunctional ionic liquids, rapid carbon dioxide conversion, cyclic carbonates, metal-free catalysts, super strong hydrogen bond donors.