Transferable force fields for adsorption of small gases in zeolites

Abstract

We provide transferable force fields for oxygen, nitrogen, and carbon monoxide that are able to reproduce experimental adsorption in both pure silica and alumino-substituted zeolites at cryogenic and high temperatures. The force field parameters can be combined with those previously reported for carbon dioxide, methane, and argon, opening the possibility for studying mixtures of interest containing the six components. Using these force field parameters we obtained some adsorption isotherms at cryogenic temperatures that at first sight were in discrepancies with experimental values for certain molecules and structures. We attribute these discrepancies to the sensitiveness of the equipment and to kinetic impedimenta that can lead to erratic results. Additional problems can be found during simulations when extra-framework cations are present in the system as their lack of mobility at low temperatures could lead to kinetic effects that hinder experimental adsorption.

Zeolites for CO2–CO–O2 Separation to Obtain CO2-Neutral Fuels

“…All the forcefields used in this work are parameterized to reproduce adsorption properties in zeolites and have been extensively validated. [19][20][21] Ideal Adsorption Solution Theory (IAST) 16 is applied to predict mixture behavior from modeling pure compound adsorption using the Dual-Site Langmuir equation 22 in Gaiast software. 23 We calculated adsorption for the CO2/CO/O2 ternary mixture and for the remaining CO/O2 binary mixture once the molecules of carbon dioxide are removed.…”

Computational simulation study of the influence of faujasite Si/Al ratio on CO2 capture by temperature swing adsorption

“…where $% is the total potential energy between atoms and at distance $% ; $ , % are the partial charges of atoms and , respectively, $% is the LJ potential well depth, $% is the LJ potential diameter, and finally 6 is the vacuum permittivity. All the force field parameters were taken from Calero et al [42,43]. These parameters are applicable to all Si/Al ratios, both at cryogenic and high temperatures.…”

Highly Selective Zeolite Topologies for Flue Gas Separation

“…The guest models and cross guest–zeolite L ‐J parameters were taken from García‐Sánchez et al . and Martin‐Calvo et al . for CO 2 and N 2 , respectively.…”

“…[26] The molecular self-diffusion was evaluated in the low-coverage regime by MD simulations in the NVT ensemblefor single molecules. [33] for CO 2 and N 2 ,r espectively.A ll these models and force fields have been published and so previously validated. The temperature T was fixed using aN osØ-Hoover thermostat.…”

“…[32] The guest modelsa nd cross guest-zeolite L-J parameters were taken from García-Sµnchez et al [32] and Martin-Calvoetal. [33] for CO 2 and N 2 ,r espectively.A ll these models and force fields have been published and so previously validated. In this regard, we omit here comparison to experimental data.…”