(380p) MOF and Zeolite Based Membranes for Carbon Dioxide and Nitrogen Separation

As atmospheric carbon dioxide (CO₂) levels continue to escalate, the pursuit of carbon capture, utilization, and storage (CCUS) has emerged as a crucial avenue for mitigating climate change. Advancements in various carbon capture technologies, including adsorbents, membranes, and solvent-based systems, are underway to address this pressing issue. A key challenge in this domain lies in effectively separating CO₂ from nitrogen (N₂) gas.

This paper centers on the utilization of mixed matrix membrane technology, where the CO₂/N₂ separation performance hinges on disparities in gas permeations. Membrane-based separation and purification techniques have garnered significant attention for carbon capture applications. Notably, microporous adsorbents such as zeolites and metal organic frameworks (MOFs) have garnered interest due to their highly porous structures, exceptional selectivity values, and adjustable porosities.

In this study, fourteen membranes were developed using a novel approach that incorporates microporous adsorbents dispersed within a blended polymer matrix consisting of methyl cellulose (MC) and polyvinyl alcohol (PVA). The membranes, which included the commercial MOF ZIF-8, zeolite 13X, and kaolin, were evaluated using a single gas permeation setup. Additionally, the impact of incorporating polyallylamine (PAH) as a chemisorbent was explored. Furthermore, membranes were synthesized both with and without a polyacrylonitrile (PAN) support to compare their performances.

Our findings reveal that MC serves as an optimal component for developing free-standing mixed matrix membranes (MMMs). Notably, a zeolite 13X-based membrane (MC/PAH/13X/PVA) demonstrated the highest N₂/CO₂ selectivity of 2.8 and a remarkable N₂ permeability of 6.9×10⁷ Barrer at ambient temperature and relatively low operating pressure on the feed side (2.36 atm). Through meticulous optimization of active layer thickness and filler weight percentages, this easily fabricated free-standing MMM, comprising readily available materials, emerges as a promising solution for CO₂ purification via nitrogen removal.