Composite nanofibrous membranes with two-dimensional ZIF-L and PVDF-HFP for CO2 separation

Abstract

Membrane gas-solvent contactors show effective CO2 capture as compared to solvent absorption. However, the overall efficiency of the capture process is compromised by the relatively low CO2 transfer rate of existing commercial membranes. Herein, we propose the integration of a two-dimensional zeolitic imidazolate framework (ZIF-L) with outstanding CO2 adsorption properties into porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibre membranes for energy-efficient CO2 separation through membrane gas absorption. Well-defined composite structures of the nanofibre membranes with ZIF-L are fabricated using the electrospinning technique. The favourable adsorption of CO2 molecules in the unique cushion-shaped cavities of ZIF-L enhances CO2 flux during both absorption and stripping processes even under mild temperature conditions when utilised in the composite nanofibre membranes. Consequently, the PVDF-HFP membrane with 5 wt% ZIF-L presents 26.7 mmol m−2 s−1 of CO2 stripping flux at 100 °C.