Fabrication of mixed matrix membranes with zinc ion loaded titanium dioxide for improved CO2 separation

To date, mixed matrix membranes with nano-filler was considered to be an effective method to enhance the gas permselectivity of membrane separation. In this work, mixed matrix membranes for the facilitated transport of CO 2 were prepared. Hexafluoroisopropylidene diphthalic anhydride - based aromatic polyimide was applied as polymeric matrix, while the zinc ion functionalized titanium dioxide spherical nano-particle was selected as nano-filler. The physical property, chemical structure and membranes morphology were characterized by FT-IR, TG, XRD, SEM, CA and XPS. Gas permselectivity was investigated using binary mixture gas of CO 2 /N 2 and CO 2 /CH 4 , respectively. The effects of nano-filler content, functional group, operation temperature on gas permselectivity were studied. Results show that the incorporation of spherical nano-filler can effectively restrict the polymer chain packing and lead to low crystallinity. By incorporation of zinc ion modified spherical nano-filler, the CO 2 permeability increased about 68.7~78.7%. PI-TiO 2 -PDA-Zn 2+ mixed matrix membranes with 7.5 wt% nano-filler addition displayed the highest CO 2 permeability (145.37 Barrer for CO 2 /N 2 feed gas and 108.36 Barrer for CO 2 /CH 4 feed gas, 1 Barrer = 7.5 × 10 -18 m 2 s −1 Pa −1 ) and satisfied CO 2 /inert gas selectivity (CO 2 /N 2 selectivity of 49.28 and CO 2 / CH 4 selectivity of 49.48). CO 2 permeability increased and selectivity decreased with the elevated temperature. Besides, the membrane exhibited good stability in the 30 days testing.