CO2 Separation Properties of a Ternary Mixed-Matrix Membrane Using Ultraselective Synthesized Macrocyclic Organic Compounds

Extra-high-performance low-level filler-loaded mixed-matrix membranes (MMMs) were fabricated by embedding a flexible cyclooligomer, calix[4]arene (CA), as a macrocyclic porous filler in two blends of a commercial polyether block amide polymer, Pebax MH 1657. Two kinds of liquid phases, PEG550 (PEG) and [OMIM][PF₆] (IL), were separately introduced into the Pebax MH 1657 matrix to prepare blended membranes for enhancing the CO₂ permeability and comparing their performance. Afterward, CA as the third generation of supramolecular hosts with high inherent affinity to CO₂ was synthesized and incorporated in the polymer blends to fabricate high-performance MMMs. The organic nature, the high compatibility of other applied additives with Pebax MH 1657 polymer, and the tiny size of CA particles were responsible for the desirable particle distribution in ternary MMMs. In the case of the Pebax/PEG550 (30 wt%)/CA (0.5 wt%) MMM, the results revealed the CO₂ permeability to be about 632.60 Barrer, with CO₂/CH₄ and CO₂/N₂ selectivities about 59.83 and 139.88, respectively. For Pebax/IL (6.5 wt%)/CA (0.5 wt%), the CO₂ permeability was about 263.82 Barrer, with CO₂/CH₄ and CO₂/N₂ selectivities about 64.39 and 152.45, respectively. Therefore, the fabricated ternary MMMs present a promising outlook for CO₂ separation, which surpasses the Robeson upper limits.