(498f) “Stitched” Graphene Oxide Flakes As Membranes for Size Selective Separation of Hydrocarbons

Industrially critical separations for molecules with sizes between 4 and 7Ã…, for example, liquid hydrocarbons with 5 to 8 carbon atoms, are very challenging using microporous membranes due to the scarcity of the appropriate porous materials for membrane fabrication. If the traditional thermal processes involving phase change are replaced by membrane processes, energy consumption for these separations can be significantly reduced. One promising membrane building block is the two-dimensional (2D) materials which might distinguish molecules in this critical range with angstrom level precision via their structure defects. However, ‘leakage’ through edges of stacked 2D flakes (a common membrane structure built from 2D materials) limits the utilization of in-plane defects or modified in-plane defects. Herein, we ‘stitched’ single-layered graphene oxide (GO) flakes together via selective growth of titanium alkoxide along the edges to seal the lateral gaps and between interlayers to lock GO flakes together, forming a continuous and stable molecular separation membrane. We found the in-plane defects of GO flakes were also modified by this preferential alkoxide growth and can be precisely tuned within the size range of 4 to 7Å. As a result, straight-chain hydrocarbon can be separated from branched ones and aromatics, demonstrating great potential for application in the petroleum industry and industries involving the separation of small organic molecules.