Pebax/two-dimensional MFI nanosheets mixed-matrix membranes for enhanced CO2 separation

Zeolite crystals as inorganic fillers were widely applied in fabricating mixed matrix membranes (MMMs) for CO2 separation. The poor filler-matrix interaction and the aggregation of high-loaded fillers in MMMs restrict their advantage of overcoming the trade-off limitation between permeability and selectivity. The novel MMMs with two-dimensional (2D) MFI nanosheets as inorganic fillers and Pebax MH 1657 as the matrix were synthesized and applied to achieve an efficient separation of CO2/CH4 gas mixture for the first time. The large interfacial contact areas between MFI nanosheets and Pebax matrix improve their compatibility to form defect-free MMMs with better mechanical properties. The high-aspect-ratio MFI nanosheets function as solid and selective barriers to make MMMs possess a significant promotion in both CO2 permeability and CO2/CH4 selectivity without the trade-off limitation. The MMM containing 5 wt% of MFI nanosheets exhibited the optimum performance with CO2 permeability of 159.1 Barrer and CO2/CH4 selectivity of 27.4. The as-prepared MMMs showed an improvement of 63.5% in CO2 permeability and 76.4% in CO2/CH4 selectivity, compared to pristine Pebax membranes.

Automated summary

Novel mixed matrix membranes with 2D MFI nanosheets as inorganic fillers were synthesized successfully for the first time, showing excellent compatibility and significant enhancement in CO2 separation performance without the trade-off limitation between permeability and selectivity.