Metal-ion-tuned metal-organic frameworks for C2H2/CO2 separation

Adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) by adsorption is a viable method for producing high-purity C2H2 required for industrial applications. However, separating C2H2 and CO2 is challenging due to their extremely similar molecular sizes and physical properties. Metal-Organic Frameworks (MOFs), as a novel porous material with high specific surface area and tunable pore size, have shown great potential in the separation and purification of light hydrocarbons. Herein, we synthesized three isoreticular Al-MOFs (Al-TCPP, Al-TCPP(Co), and Al-TCPP(Fe)) by modulating metal ions at the porphyrin center, all of which can effectively separate C2H2/CO2. The addition of metal ions can regulate and improve the separation selectivity of C2H2/CO2. Compared with the parent Al-TCPP, the IAST selectivities of Al-TCPP(Co) and Al-TCPP(Fe) for equimolar C2H2/CO2 increased from 1.73 to 3.66 and 4.43, respectively. Breakthrough experiments validate their efficient separation of C2H2/CO2. Furthermore, they all exhibit excellent hydrothermal stability, laying the foundation for practical applications.