Improving CO2 capture in UTSA-16(Zn) via alkali and alkaline earth metal Introduction: GCMC and MD simulations study

Metal Organic Frameworks (MOFs) have recently emerged as highly attractive materials, representing a significant advancement in the field of carbon dioxide (CO2) capture. In this study, our objective is to validate existing experimental data and investigate the CO2 adsorption properties of UTSA-16(Zn) by modifying its primary adsorption sites with alkali and alkaline earth metal cations. To achieve this, we employ Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) simulations to explore the CO2 adsorption uptake of the newly designed MOFs. Through MD simulations, we utilize the Radial Distribution Function (RDF) to identify the primary CO2 adsorption sites within UTSA-16(Zn). Our results reveal that the potassium cation (K+) serves as the primary adsorption site. Building upon this information, we investigate the impact of replacing K+ with other metal cations such as Li+, Na+, Rb+, Be2+, Mg2+, and Ca2+ on the CO2 adsorption capacity of the MOF. Our findings indicate that Be2+ and Mg2+ have a positive influence on the CO2 uptake of the MOF due to their higher electronegativity compared to the other metal cations. Consequently, Be-UTSA-16(Zn) and Mg-UTSA-16(Zn) demonstrate superior performance in CO2 adsorption compared to UTSA-16(Zn) under various inlet feed conditions. Notably, when pure CO2 is supplied, the aforementioned new MOFs exhibit an increase in CO2 adsorption capacity of 8.81 % and 5.37 %, respectively, in comparison to UTSA-16(Zn). These findings provide valuable insights into the CO2 adsorption behavior of the newly designed MOFs and suggest potential strategies for designing efficient CO2 capture MOFs.