Scale-up synthesis and shaping of MIL-160(Al) applicable for efficient CO2 adsorption and separation

The scale-up preparation and shaping of Metal-Organic Frameworks (MOFs) is crucial for achieving its industrial application for CO2 capture. In this work, MIL-160(Al)-5L powder was successfully produced in a 5 L reactor with an environmentally friendly and easy route under mild conditions, and then shaped into cylindrical particles via a simple extrusion method using dilute nitric acid as the binder. Mechanical performance tests indicated that the average crushing stress of the particles was 1.45 MPa, which slightly exceeded that of the commercial molecular sieve Zeolite-13X. Characterization of the MIL-160(Al)-5L powder and its shaped particles using XRD, FTIR, and BET analysis revealed there are no significant structural changes compared to experimental MIL-160(Al) except only a 5.93 % decrease in BET surface area for the shaped particles. Equilibrium adsorption isotherms for CO2, CH4, and N2 at 298 K and 273 K were well fitted to the Langmuir-Freundlich model. The CO2 adsorption capacity of the MIL-160(Al)-5L powder and its shaped particles were 3.13 mmol/g and 2.97 mmol/g at 298 K, respectively. Ideal adsorption solution theory (IAST) calculations indicated similar selectivity for CO2/CH4 and CO2/N2 across all samples. Breakthrough experiments demonstrated that the shaped sample possesses stable dynamic adsorption capacity and separation performance for simulated biogas, and its structural integrity is maintained after five consecutive breakthrough-regeneration cycles. Comparison with other shaped MOFs also highlights the advantages of low binder cost, superior mechanical, and adsorption properties, which suggests that MIL-160(Al) has shown potential applications prospect in CO2 capture and gas separation. This work also provides a promising preparation method for developing stable and shaped MOFs for industrial applications.