Enhanced pervaporation performance of MIL-101 (Cr) filled polysiloxane hybrid membranes in desulfurization of model gasoline

• Hybrid membranes by incorporating MIL-101 into PDMS matrix were fabricated.
• Extra free volume cavities and mass transfer channels were generated in membranes.
• Permeability and selectivity of the membranes were increased simultaneously.

Hybrid membranes were fabricated with active layers composed of polydimethyl siloxane (PDMS) and metal organic framework MIL-101 (Cr), together with support layers composed of polyvinylidene fluoride (PVDF). Transmission electron microscopy (TEM), X-ray diffraction (XRD) and nitrogen adsorption were used to study the structure of MIL-101 (Cr) particles; scanning electron microscopy (SEM), infrared spectrum (IR), thermogravimetric analysis (TGA), thermomechanical analysis and positron anihilation lifetime spectroscopy (PALS) were employed to characterize the structural morphology, free volume property, thermal and mechanical features of the membranes. The effect of MIL-101 (Cr) incorporation on swelling and pervaporation performance of the hybrid membranes were evaluated with thiophene and n-octane mixture as model gasoline. The packing of PDMS chains was interrupted by MIL-101 (Cr), thus the fractional free volume was increased. Accordingly, the separation performance including permeation flux and selectivity was increased remarkably. The optimal performance was achieved when the weight fraction of MIL-101 to PDMS was 6% with a flux of 5.2 kg·m−2 h−1 (increased by 136% compared with the PDMS control membrane) and an enrichment factor of 5.6 (increased by 38% compared with the PDMS control membrane).