Hierarchically Porous Structured Adsorbents with Ultrahigh Metal–Organic Framework Loading for CO2 Capture

• Published in: ACS applied materials & interfaces 2024-09, Vol.16 (38), p.50785-50799
• Main Authors: Gebremariam, Solomon K., Varghese, Anish Mathai, Ehrling, Sebastian, Al Wahedi, Yasser, AlHajaj, Ahmed, Dumée, Ludovic F., Karanikolos, Georgios N.
• Format: Article
• Language: English
• Subjects: Energy, Environmental, and Catalysis Applications
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.4c10730

Metal–organic frameworks (MOFs) have emerged as promising candidates for CO2 adsorption due to their ultrahigh-specific surface area and highly tunable pore-surface properties. However, their large-scale application is hindered by processing issues associated with their microcrystalline powder nature, such as dustiness, pressure drop, and poor mass transfer within packed beds. To address these challenges, shaping/structuring micron-sized polycrystalline MOF powders into millimeter-sized structured forms while preserving porosity and functionality represents an effective yet challenging approach. In this study, a facile and versatile strategy was employed to integrate moisture-stable and scalable microcrystalline MOFs (UiO-66 and ZIF-8) into a poly­(acrylonitrile) matrix to fabricate readily processable, millimeter-sized hierarchically porous structured adsorbents with ultrahigh MOF loadings (∼90 wt %) for direct industrial carbon capture applications. These structured composite beads retained the physicochemical properties and separation performance of the pristine MOF crystal particles. Structured UiO-66 and ZIF-8 exhibited high specific surface areas of 1130 m2 g–1 and 1431 m2 g–1, respectively. The structured UiO-66 achieved a CO2 adsorption capacity of 2.0 mmol g–1 at 1 bar and a dynamic CO2/N2 selectivity of 17 for a CO2/N2 gas mixture with a 15/85 volume ratio at 25 °C. Furthermore, the structured adsorbents exhibited excellent cyclability in static and dynamic CO2 adsorption studies, making them promising candidates for practical application.