High-performance gas separation using mixed-matrix composite membranes containing graphene nanoplatelets

Mixed-matrix composite membrane (MMCM) made from a dense selective layer filled with various filler on the top of a porous support layer is an effective method to obtain high gas separation performance compared to the conventional mixed-matrix membrane. In this study, the high CO2-selective Pebax-1657 layer was coated onto the porous PES support layer with desirable mechanical stability, and then graphene nanoplatelets (GNPs) were embedded into Pebax selective layer at different concentrations (below 1 wt%) to evaluate the influence of GNPs on the separation properties of gases such as CO2, O-2, and N-2 with distinct features under fixed pressure and temperature (4 bar and 25 degrees C). The prepared MMCMs were characterized by SEM, XRD and FTIR analysis. The single gas separation results showed that the permeability and selectivity of MMCMs were simultaneously increased by GNP loading. The MMCM containing 0.7 wt% GNP considerably improved the CO2 permeability, CO2/N-2,N- and O-2/N-2 selectivities about 68%, 50%, and 28%, respectively, in comparison with the pure MMCM. This was attributed to the higher aspect ratio of GNPs, which can produce more interaction with Pebax and CO2 gas. Thus, fabrication of the GNP-embedded MMCMs is an effective strategy to improve the gas separation properties. [GRAPHICS] .

Automated summary

Embedding graphene nanoplatelets into the Pebax selective layer at different concentrations can significantly improve the CO2 permeability and selectivity of MMCMs. The higher aspect ratio of GNPs contributes to more interactions with Pebax and CO2 gas, leading to enhanced gas separation properties.