(520c) Molecular Simulation of Adsorption and Diffusion in Rigid Nanoporous Amorphous Materials

The development of publicly available materials databases for materials including zeolites (IZA-SC), metal organic frameworks (CoRE-MOF), and inorganic materials (The Materials Project) has been a key enabler of high-throughput computational screening and data-driven discovery of materials for potential use in new technologies. We recently introduced a similar database for structures of porous rigid amorphous materials¹, an important class of materials for which no such resource was available. The database includes atomically detailed structures of disordered materials like amorphous carbons, kerogens, hyper-cross-linked polymers etc. generated using a wide range of simulation techniques by multiple research groups. We present extensive computational analyses for material characterization by calculating a series of scalar (e.g., accessible surface area) and vector (e.g., pore size distribution) descriptors. A variety of gas adsorption isotherms for both single component and binary mixtures are predicted for each structure.We also discuss the agreement between binary adsorption data and predictions from the Ideal Adsorbed Solution Theory.

In addition to adsorption isotherms, we have computed the diffusion coefficients of CH₄ and CO₂ in several of these structures. We present a diverse collection of molecular diffusivities in amorphous materials and examine their concentration dependence by comparing data from adsorption and diffusion simulations. We also discuss the correlations of computed self-diffusivities with scalar descriptors and Knudsen diffusivities.

References:

1. Thyagarajan, R.; Sholl, D. S. A Database of Porous Rigid Amorphous Materials. Chem. Mater. 2020, 32, 8020-8033.