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Catalytic fixation of CO2 to cyclic carbonates over biopolymer chitosan-grafted quarternary phosphonium ionic liquid as a recylable catalyst
Ist Teil von
Applied catalysis. A, General, 2014-08, Vol.484, p.26-32
Ort / Verlag
Elsevier B.V
Erscheinungsjahr
2014
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
•For the first time quarternary phosphonium IL grafted on biopolymer CS, CS-[BuPh3P]Br, was fabricated.•CS-[BuPh3P]Br was used as catalyst for the cycloaddition reaction.•CS-[BuPh3P]Br shows good catalytic activity, stability and recyclability.•The good activity is attributed to synergistic effect of OH, P cations, and Br–.
We prepared chitosan-grafted quarternary phosphonium ionic liquid (1-butyl-triphenylphosphonium bromide) by a simple method and used it as catalyst for the synthesis of cyclic carbonates through CO2 cycloaddition to epoxides in the absence of co-catalyst and solvent. High yield of propylene carbonate (96.3%) is obtained at 120°C and 2.5MPa in 4h. We studied the roles of chitosan hydroxyl groups and ionic liquid counter anions on catalytic activity. It is proposed that the facilitation of ring opening of epoxides is a combined result of polarization (by hydrogen bonding due to hydroxyl groups), electronic interaction (by [BuPh3P]+), and nucleophilic attack (by bromide anion). The catalyst can be easily recovered and reused as demonstrated in a test of five runs without showing any significant loss of activity. From the view point of commercial application, the catalyst is attractive because it is low-cost, ecology-safe, stable and efficient. Furthermore, it is potentially applicable for fixed-bed continuous flow reactors.