Eco-Friendly Synthesis and Morphology Control of MOF-74 for Exceptional CO₂ Capture Performance with DFT Validation

Abstract

Metal-Organic Frameworks (MOFs) are increasingly acknowledged for their broad applications in direct carbon dioxide (CO2) capture from the atmosphere. However, traditional synthesis methods often involve toxic compounds, posing significant environmental concerns. This study introduces a rapid and eco-friendly synthesis method for MOF-74 (G-MOF-74), emphasizing controlled morphology to optimize its structural characteristics. By achieving a tailored morphology, this approach enhances the CO2 adsorption capacity. The resulting structure, characterized by a high surface area, significantly increases the number of accessible active sites for CO2 molecules, thereby improving overall gas capture performance. The G-MOF-74 demonstrates a notable adsorption capacity of 5.86 mmol/g for CO2 and 0.91 mmol/g for nitrogen (N2) at 1.1 bar, highlighting its excellent potential for bulk gas separation applications. Furthermore, the isosteric heat values were determined to be 20.5 kJ/mol for CO2 adsorption and 13.2 kJ/mol for N2 adsorption. In the realm of kinetic modeling, the Weber and Morris model emerged as the most suitable, as evidenced by an R2 value of 0.968. The Ideal Adsorbed Solution Theory (IAST) analysis, conducted under flue gas conditions, demonstrated a noteworthy selectivity value of 27.5. To gain a deeper understanding of the adsorption mechanism and optimize the material for CO2 capture, Density Functional Theory (DFT) calculations and Monte Carlo simulations were employed alongside the experimental evaluation. To assess the cyclic stability of G-MOF-74, a series of 15 adsorption–desorption cycles were executed with 150 °C and 100 °C regeneration temperature, revealing a modest capacity loss of 9.91 % and 7.33 %, respectively. These findings underscore the promising potential of G-MOF-74 as an environmentally friendly adsorbent for gas separation applications.

Group Members

William A. Goddard III

Charles and Mary Ferkel Professor