(199g) Modeling of Adsorption in Pristine and Defective Metal Organic Framework Materials

Metal-organic frameworks (MOFs) have attracted significant interest for adsorption due to their high degree of tailorability and large specific surface areas. The combination of tailorability and well-defined crystalline pores makes MOFs very promising candidates for highly selective adsorption.

Molecular-level modeling of adsorption and diffusion in MOFs almost always relies on models of MOFs that are defect-free (pristine). However, all real MOFs have defects, which affect adsorption by changing the types of pores within the MOFs. A fundamental understanding of how defects impact adsorption is important for identifying the limits of the performance of real material, developing improved design rules for new improved materials, and predicting and maximizing utilization of the material.

In this study, we focus on the study of how adsorption correlates with the number and types of defects. We initially consider UiO-66 with different levels of missing linker defects. The structures of the generated defective MOFs were optimized using periodic density functional theory with the CP2K simulation package. Adsorption isotherms were generated by carrying out grand canonical Monte Carlo (GCMC) simulations in Raspa. We investigated the effect of different adsorbate-adsorbent charge schemes by comparing isotherms with no framework charges and atomic charges calculated using DDEC6 and EQEQ methods. Different potentials for adsorbate were also tested for more accurate modelings.