Enhanced selectivity in thin film composite membrane for CO2 capture through improvement to support layer

Abstract

Membranes with highly selectivity and permeance are greatly desirable for CO2 capture since they are energy-saving. Generally thin-film composite membranes (TFCMs) achieve enhanced CO2 permselectivity by decreasing the thickness of membranes and engineering the membrane with integrate structure at the molecular level, which suffer from the limit of thickness reduction and extremely precise processing. In this work, we propose a facile and versatile support layer modification strategy to overcome the above technical barriers, where the support layer is the porous electrospun nanofiber substrate based on MOF (three MOF types are used, UIO66-NH2, ZIF-8 and HKUST-1). The introduction of MOFs in the support layer not only enables the electrospun nanofibers to support TFCMs well, but also enhances the CO2 selectivity without losing the permeability obviously. Because of this design, the TCFMs developed by this work achieves a CO2 permeance of 3690 GPU and a CO2/N2 selectivity of 92, which is far surpassing the threshold for the requirement of economic evaluations and superior to most comparable TCFMs. In addition, the TFCMs have a stable selective performance during the 40-day aging study. This generic supported-layer modification strategy is expected to provide a new avenue to address the challenges of scalable fabrication of TCFMs with excellent CO2 separation performance for carbon capture.