First-principles studies of small molecule absorption kinetics in diamine-appended metal-organic frameworks

Recently, a family of diamine-appended metal-organic frameworks (MOFs) has demonstrated selective and tunable adsorption via novel reversible non-Langmuir stepped isotherms, making them promising for carbon capture applications. Here, we use first principles van der Waals-corrected density functional theory calculations, as well as molecular dynamics and computations of NMR chemical shifts, to understand the structure, kinetics, and selectivity associated with the stepped isotherms in environments relevant to flue gas conditions. We compare binding energies with experiments, and predict intermediate and final structures to understand the measured isotherms. We focus on the role that SO2, a component of flue gas, plays in degrading MOF CO2 adsorption through studying SO2 binding energies and how SO2 disrupts the kinetics of CO2 adsorption. This work is supported by DOE, and computational resources are provided by NERSC.