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

Abstract

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.

Integration of Stable Ionic Liquid-Based Nanofluids into Polymer Membranes. Part II: Gas Separation Properties toward Fluorinated Greenhouse Gases

“…Given the promising results obtained with MMMs, mainly focused on CO 2 selective separation [42][43][44][45][46], in this work we explore for the first time the use of MMMs functionalized with exfoliated graphene nanoplatelets (xGnP) for the separation of HFCs. In this sense, the role of pristine graphene in this type of applications, given its bidimensional structure and the fact that it is impermeable to gases, is to generate some degree of tortuosity within the polymer matrix and thus, modify the path of the gas molecules during permeation [47,48].…”

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption**

“…Conventional strategies to incorporate the cavities of porous molecules into solid materials can be briefly summarized: (1) frameworks connected by supramolecular interactions 22,31 or metalligand coordination bonds, [32][33][34][35] (2) organic polymers or porous networks anchored by porous molecules covalently, 36,37 and (3) PMCs dispersed as porous additives in organic polymers. [38][39][40] Coskun and coworkers have prepared a conjugated microporous polymer with one-dimensional (1D) channels based on the cross-coupling of pillar [5]arene, and used it in C3H8/CH4 separation. 41 Janiak and coworkers encapsulated intrinsic barrel-shaped porous cucurbit [6]uril cages into MIL-101 for enhanced CO2 separation.…”

Exploring NH3 Transport Properties by Tailoring Ionic Liquids in Pebax-Based Hybrid Membranes

“…Poly­(ether- block -amide) copolymer (Pebax) is a hot membrane material for gas separation, especially for separating polar gases such as CO 2 from nonpolar gases. − Moreover, the bulk properties of ILs have significant effects on the transport properties of gases in IL-containing membranes. Tuning interactions between ILs and CO 2 for obtaining higher absorption capacity is the leading step in improving CO 2 solubility in membranes, and CO 2 diffusion in membranes largely depends on the viscosities of ILs. , Different from the abovementioned gases, NH 3 is a typical basic gas. The applications of Pebax-based membranes in the separation of NH 3 have not been explored.…”