Progress in polyvinyl alcohol membranes with facilitated transport properties for carbon capture

Abstract

Polymeric membranes offer simple operation and high flexibility to be integrated into carbon capture, utilization, and storage (CCUS) strategies, but the solution-diffusion mechanism limits their separation performance. CO2 facilitated transport membranes have been extensively developed to increase the techno-economic potential of CCUS. Polyvinyl alcohol (PVA) membranes can be easily fabricated as the selective layer on porous support through different coating strategies. Recent works focused on various additives such as fixed amine carriers, mobile amine carriers, moiety content promoters, swelling agents, and more to improve CO2 facilitated transport through PVA membranes. The past studies focusing on PVA membranes in carbon capture included the use of different additives, which could be categorized into fixed amine carriers, mobile amine carriers, hydrophilic polymers, carbonaceous materials, inorganic particles and polyether block amide (PEBA). Adding both fixed amine carriers and mobile amine carriers could promote the CO2 separation beyond Robeson upper bound. However, the hydrophilic polymers only improved CO2 separation below Robeson upper bound. Carbon nanotubes enhanced the mechanical properties, while the functionalized graphene oxide facilitated CO2 permeation effectively. Inorganic particles such as zinc oxide, silica, and alumina offered more opportunities to improve the swelling of PVA membranes and promote CO2 separation beyond the Robeson boundary. The CO2 separation performance of PVA membranes could be enhanced by increasing the relative humidity, but severe corrosion could be induced simultaneously. Hence, future works should focus on incorporating inorganic additives with amine functionalization to PVA membranes besides studying the humidity control for promoting facilitated transport of CO2.