Ultrahigh Carbon Dioxide-Selective Composite Membrane Containing a γ-CD-MOF Layer

Mixed matrix membranes (MMMs) for CO2 separation have overcome the trade-off between gas permeability and gas selectivity to some extent. However, most MMMs still are prepared in lab- and pilot-scales since the permeability and selectivity of CO2 are not good enough to reach the economically available requirements. Moreover, the fabrication of few MMMs with good separation performance is time-consuming or need harsh conditions. In this study, a novel MOF-based composite membrane (PAN-gamma-CD-MOF-PU membrane) was successfully fabricated by a facile and fast spin-coating method. In the two-step coating process, we applied a uniform selective layer of gamma-cyclodextrin-MOF (gamma-CD-MOF) on porous polyacrylonitrile and then coated a layer of polyurethane on the gamma-CD-MOF layer. The entire membrane formation process was about 30 s. The formation of a unique gamma-CD-MOF layer greatly improved the separation ability of CO2 (the CO2 permeability is 70.97 barrers; the selectivity to CO2/N-2 and CO2/O-2 are 253.46 and 154.28, respectively). The gas separation performance can exceed the Robeson upper limit obviously and the selectivity is better than other MOF-based composite membranes. In addition, the PAN-gamma-CD-MOF-PU membrane is strong and flexible. Therefore, the PAN-gamma-CD-MOF-PU membrane developed in this study has great potential in large-scale industrial separation of CO2.

Automated summary

A novel MOF-based composite membrane was successfully fabricated using a fast and simple spin-coating method, significantly improving the separation ability and selectivity of CO2. The membrane showed superior performance compared to other composite membranes and has great potential for large-scale industrial CO2 separation applications.