Removal of CO2 from high-temperature flue gas using PDMS/IL composite membranes

Abstract

Membrane separation of CO₂ from high-temperature flue gas has economic benefits. Thus, the development of thermally-stable polymeric membranes with efficient permselectivity is crucial. In this work, we designed a composite membrane consisting of a homogeneously distributed ionic liquid (IL) in a PDMS network using a physical blending approach. Benefiting from the strong physical-crosslinking interaction between PDMS and the IL, the polymer chain mobility is inhibited, and the structural stability of the composite membrane is improved thus maintaining excellent gas separation performance at elevated temperatures from 25 °C to 150 °C. The obtained composite membranes display a superior CO₂ permeance of 22.6 GPU and a high CO₂/N₂ selectivity of 21.4 at 150 °C. More significantly, the separation performance of the composite membrane can return back to the initial value when the temperature drops to room temperature. Additionally, the composite membrane retains its good CO₂/N₂ separation performance during an 80 h continuous operation at 150 °C, further indicating the high thermal stability of the composite membrane. The polymer/IL blend system described here is very promising for the removal of CO₂ from high-temperature flue gas.