Advances in high permeability polymer-based membrane materials for CO2 separations

Abstract

Membrane processes have evolved as a competitive approach in CO₂ separations compared with absorption and adsorption processes, due to their inherent attributes such as energy-saving and continuous operation. High permeability membrane materials are crucial to efficient membrane processes. Among existing membrane materials for CO₂ separations, polymer-based materials have some intrinsic advantages such as good processability, low price and a readily available variety of materials. In recent years, enormous research effort has been devoted to the use of membrane technology for CO₂ separations from diverse sources such as flue gas (mainly N₂), natural gas (mainly CH₄) and syngas (mainly H₂). Polymer-based membrane materials occupy the vast majority of all the membrane materials. For large-scale CO₂ separations, polymer-based membrane materials with high CO₂ permeability and good CO₂/gas selectivity are required. In 2012, we published a Perspective review in Energy & Environmental Science on high permeability polymeric membrane materials for CO₂ separations. Since then, more rapid progress has been made and the research focus has changed significantly. This review summarises the advances since 2012 on high permeability polymer-based membrane materials for CO₂ separations. The major features of this review are reflected in the following three aspects: (1) we cover polymer-based membrane materials instead of purely polymeric membrane materials, which encompass both polymeric membranes and polymer–inorganic hybrid membranes. (2) CO₂ facilitated transport membrane materials are presented. (3) Biomimetism and bioinspired membrane concepts are incorporated. A number of representative examples of recent advances in high permeability polymer-based membrane materials is highlighted with some critical analysis, followed by a brief perspective on future research and development directions.