Metal confined in metal-organic framework-based mixed matrix membranes for efficient butadiene recognition separation

The efficient separation of butadiene (1,3-C4H6) from C-4 hydrocarbons is a critical step in petrochemical processes. However, the traditional cryogenic distillation suffers from energy-intensity and serious environmental stress, necessitating the development of alternative technologies for efficient 1,3-C4H6 separation. Herein, a 1,3-C4H6 recognition mixed matrix membrane is reported via incorporating metal copper encapsulated a metal-organic framework (CuBTC@Cu) into elastic poly(dimethylsiloxane) (PDMS). The resulting CuBTC@Cu/PDMS membrane can efficient separate 1,3-C4H6 from various C-4 hydrocarbons including 1,3-C4H6/n-C4H8, 1,3-C4H6/iso-C4H8, 1,3-C4H6/n-C4H10 and 1,3-C4H6/iso-C4H10, yielding superior selectivity of 5.11, 6.35, 4.78, and 10.30, respectively, with 1,3-C4H6 permeability of 53240 Barrer. Notably, the appropriate pi-complexation interaction between butadiene molecules and CuBTC@Cu as well as suitable transmission channel size enable the membrane only permeable to 1,3-C4H6 and block the permeation of other C-4 hydrocarbons, showing a unique 1,3-C4H6 recognition behavior in membrane separation. The concept of affinity-relying separation combining molecular sieving would open a new direction for designing gas membranes for efficient light hydrocarbon separations.