The efficient separation of hydrogen from methane and light hydrocarbons for clean energy applications remains a technical challenge in membrane science. To address this issue, we prepared a graphene-wrapped MFI (G-MFI) molecular-sieving membrane for the ultrafast separation of hydrogen from methane at a permeability reaching 5.8 × 10 6 barrers at a single gas selectivity of 245 and a mixed gas selectivity of 50. Our results set an upper bound for hydrogen separation. Efficient molecular sieving comes from the subnanoscale interfacial space between graphene and zeolite crystal faces according to molecular dynamic simulations. The hierarchical pore structure of the G-MFI membrane enabled rapid permeability, indicating a promising route for the ultrafast separation of hydrogen/methane and carbon dioxide/methane in view of energy-efficient industrial gas separation.

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An ionic liquid, N,N,N-trimethyl-N-propylammonium bis­(trifluoromethanesulfonyl)­imide (TMPA TFSI), was transformed from a liquid phase to another fluidic phase by application of the threshold magnetic field at constant temperature (T). The magnetic-field-induced (MFI) phase transformation was detected by the electric potential generated between two Pt electrodes set to the bottom and upper parts in a TMPA TFSI liquid during sweep of the magnetic field (B). The magnetic susceptibility and Verdet constant of TMPA TFSI also were slightly changed over 3 T. The MFI phase formation was almost completed within 3 h after TMPA TFSI liquid was exposed to a 6 T magnetic field, as demonstrated by the melting behavior of TMPA TFSI solid frozen instantaneously under 6 T. Multivariate analysis of the Raman spectra suggested that the MFI transformation should be associated with the conformational change of the transoid-to-cisoidlike species of TFSI ions. A B–T phase diagram of TMPA TFSI is proposed.