High-efficiency CO(2) separation using hybrid LDH-polymer membranes

Membrane-based gas separation exhibits many advantages over other conventional techniques; however, the construction of membranes with simultaneous high selectivity and permeability remains a major challenge. Herein, (LDH/FAS)(n)-PDMS hybrid membranes, containing two-dimensional sub-nanometre channels were fabricated via self-assembly of unilamellar layered double hydroxide (LDH) nanosheets and formamidine sulfinic acid (FAS), followed by spray-coating with a poly(dimethylsiloxane) (PDMS) layer. A CO(2) transmission rate for (LDH/FAS)(25)-PDMS of 7748 GPU together with CO(2) selectivity factors (SF) for SF(CO(2)/H(2)), SF(CO(2)/N(2)) and SF(CO(2)/CH(4)) mixtures as high as 43, 86 and 62 respectively are observed. The CO(2) permselectivity outperforms most reported systems and is higher than the Robeson or Freeman upper bound limits. These (LDH/FAS)(n)-PDMS membranes are both thermally and mechanically robust maintaining their highly selective CO(2) separation performance during long-term operational testing. We believe this highly-efficient CO(2) separation performance is based on the synergy of enhanced solubility, diffusivity and chemical affinity for CO(2) in the sub-nanometre channels.