Synergistic tuning mixed matrix membranes by Ag+-doping in UiO-66-NH2/polymers of intrinsic microporosity for remarkable CO2/N2 separation

Novel mixed matrix membranes (MMMs) with superior CO 2 /N 2 separation properties are of great importance for post-combustion CO 2 capture from flue gas . Metal-organic frameworks (MOFs) as one of the most attractive porous fillers for MMMs fabrication, are considered to provide a solid molecular sieving mechanism for enhancing CO 2 /N 2 selectivity. However, it causes the reduction in gas permeability and limits its further industrialization. Herein, we proposed a new strategy for filler functionalization by doping silver ions (Ag + ) into UiO-66-NH 2 nanoparticles through the double-solvent method and used for the preparation of advanced MMMs. The double-solvent method is benefits for the enrichment of Ag + in the hydrophilic pores of UiO-66-NH 2 . As a result, the prepared novel MMMs called Ag + @UiO@PIM-1 with the polymers of intrinsic microporosity (PIMs) as polymer matrix , show outstanding CO 2 permeability. According to the mixed gases (CO 2 /N 2  = 10:90) permeation experiments under 25 °C and 2 bar, the membrane with 30%Ag + @10%UiO loading achieves more than 65% increase in CO 2 /N 2 selectivity (∼30) and 120% in CO 2 permeability (>15,000 Barrer) compared to the pristine PIM-1 membrane. By optimizing the Ag + doping amount and Ag + @UiO loading content, the separation performance exceeds the 2019 CO 2 /N 2 upper bound. To figure out the separation mechanism, the pore texture properties and CO 2 affinity of the functional filler (Ag + @UiO) together with the membrane structure were characterized by XPS , PXRD , SEM, gas sorption , etc. The synergistic mechanisms by combing CO 2 facilitated transport and molecular sieving from pore regulation were identified to enable advanced CO 2 /N 2 membrane separation .