Importance of Blocking Inaccessible Voids on Modeling Zeolite Adsorption: Revisited

We have carried out a geometry-based analysis of the need of artificial blocking in a collection of zeolites, for various gases of industrial and environmental relevance (carbon dioxide, methane, nitrogen, oxygen, and argon), and we have studied its influence on the heats of adsorption and saturation uptakes, which are key properties for gas separation and storage, respectively. Our results highlight the importance of blocking some of the pores of the zeolites in order to avoid the spurious inclusion of guest molecules in inaccessible regions during Monte Carlo simulations. We can thus avoid the overestimation of adsorption and also identify nonadsorbent zeolites for these gases by introducing pore blockings. We discuss the limitations of the current approaches to perform automatic blocking, and we check the reliability of the results obtained with our blocking method, by comparing with self-diffusion coefficient values calculated using molecular dynamics simulations.