Post-synthetic ligand exchange as a route to improve the affinity of ZIF-67 towards CO2

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-11, Vol.476, p.146846, Article 146846
• Main Authors: Villalgordo-Hernández, David, Antonio Diaz-Perez, Manuel, Balloi, Valentina, Anabel Lara-Angulo, Mayra, Narciso, Javier, Carlos Serrano-Ruiz, Juan, Ramos-Fernandez, Enrique V.
• Format: Article
• Language: English
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.146846

•Enhanced CO2 Selectivity: Ligand exchange improves affinity for CO2 over CH4.•Structural Advancements: Exchange induces contraction and uncoordinated nitrogen sites.•Optimized Gas Adsorption: Tailored material demonstrates superior performance.•Applications Potential: Modified ZIF-67 holds promise for CO2/CH4 separation. The Zeolitic Imidazolate Framework 67 (ZIF-67) is a highly promising material owing to its exceptional thermal stability, large specific surface area, cost-effectiveness, and versatile applications. One of the potential applications of ZIF-67 is gas separation processes, among which the separation of CO2/CH4 mixtures has attracted great interest nowadays in the biogas sector. However, when it comes to CO2/CH4 separation, ZIF-67 falls short as it lacks the desired selectivity despite its high adsorption capacity. This limitation arises from its relatively low affinity towards CO2. In this study, we have addressed this issue by partially exchanging the ligand of ZIF-67, specifically replacing 2-methylimidazole with 1,2,4 (1H) triazole, which introduces an additional nitrogen atom. This modification resulted in ZIF-67 showing significantly enhanced affinity towards CO2 and, as a result, greater selectivity towards CO2 over CH4. The modified materials underwent thorough characterization using various techniques, and their adsorption capacity was evaluated through high-pressure adsorption isotherms. Furthermore, their separation performance was assessed using the Ideal Solution Adsorption Theory, which provided valuable insights into their potential for efficient gas separation.