Dual facilitated transport of CO2 using electrospun composite membranes containing Ionic liquid

Abstract

Dual facilitated CO2 transport membranes with good CO2/CH4 separation were developed using electrospun polyelectrolyte and room temperature ionic liquids (RTILs). Electrospinning was used to fabricate sites for the fixation of the RILL carrier using polyelectrolyte as well as pores for the impregnation of the RTIL. 1-Hexyl-3-methylimidazolium tetratluoroborate ([hmim][BF4]) and 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]) were chosen as CO2 car nets for the facilitated transport membrane. The CO2 car net is present in two phases; one is liquid impregnated into the pores, and the other is located at fixed sites on a solid polyelectrolyte matrix. Two different electrospun composite membranes were prepared by the adsorption of RTIL onto electrospun polyvinylpyrrolidone (PVP) membranes with or without polyelectrolyte (Nafion). The polyelectrolyte Nafion provides fixation sites for the RTIL as well as the formation of pores, whereas PVP only provides pores for impregnation of the RTIL. The ideal CO2/CH4 separation factors and permeances of electrospun PVP/Nafion composite membranes with RTIL were higher than those of supported ionic liquid membrane, and the CO2/CH4 selectivity was found to be 26.3 with a CO2 permeance of 19 GPU for electrospun PVP/Nafion composite membrane containing [hmim][PF6]. The CO2 permeance improved ca. 10% over that of dense composite membrane containing RILL due to the dual facilitated transport both in liquid and solid-like phase. (C) 2015 Elsevier B.V. All rights reserved.