Mixed-Matrix Membranes With Layered Fluorine–Cerium Nanosheets for CO2/CH4 Separation

Versatile layered fluoride-cerium nanosheets with thickness about 1.60 nm denoted as F-Ce are fabricated by a convenient and environmentally friendly approach. Then, Pebax-1657 is used as the polymer matrix and F-Ce as inorganic fillers to produce mixed-matrix membranes (MMMs) for gas separation. Versatile functions in enhancing the membrane performances are exhibited by F-Ce with intrinsic dual channels. On one hand, the abundant mesoporous slits in F-Ce enhance gas diffusion, constructs high-speed transport pathways of CO 2 and improve CO 2 permeability; on the other hand, molecular-sieving d -spacing in F-Ce endows MMMs with prominently preferential CO 2 transport, which favors the increment of CO 2 /CH 4 selectivity. Furthermore, F-Ce tends to horizontal arrangement and endows the MMMs with preeminent polymer–nanosheet interfacial compatibility, thereby facilitating the superior performance of F-Ce in MMMs and leading to improvements in both permeability and selectivity. In addition, the F-Ce exhibits an affinity for CO 2 and constructs “CO 2 -philic, CH 4 -phobic” regions in MMMs, and the CO 2 -philic regions significantly improves CO 2 /CH 4 solubility selectivity and selectivity. The permeability and selectivity of MMMs in humidified state come to maximum values, 1508 Barrer and 37, respectively, at 8 wt% F-Ce loading, overcoming Robeson Upper Bound (2008). Besides, the mechanical stability of MMMs was investigated.