Adsorption of Non Polar and Quadrupolar Gases in Siliceous Faujasite: Molecular Simulations and Experiments

Abstract

The adsorption of non polar (argon, methane) and quadrupolar (carbon dioxide, nitrogen) gases on siliceous Faujasite at ambient temperature and high pressure conditions up to 50 bar, is investigated both experimentally and theoretically by combining Microcalorimetry and Grand Canonical Monte Carlo techniques. The aim of this present work is to evaluate the adsorption isotherms as well as the evolution of the differential enthalpies of adsorption as a function of coverage, for each of the gases under study, and to compare directly results of simulations with our own experimental data. To this purpose, the choice of reliable interatomic potentials required to describe both the adsorbate/framework and adsorbate/adsorbate interactions is crucial. This work is thus based on new transferable pair potential models for methane and carbon dioxide, recently developed by one of the authors using quantum mechanical methods. Finally, we propose a simplified model which can relate the differential enthalpy of adsorption at low coverage to the polarisability of the gases.

Adsorption of carbon dioxide in SAPO STA-7 and AlPO-18: Grand Canonical Monte Carlo simulations and microcalorimetry measurements

“…2b. This result is consistent with similar enthalpy profile observed for the adsorption of CO 2 in purely siliceous zeolites such as silicalite (Choudary and Mayadevi 1996;Dunne et al 1996;Hampson and Rees 1993) or DAY (Maurin et al 2005b), presenting as well a homogeneous energetic surface.…”

“…For carbon dioxide, we used an atomic point charge model with the following charges (in electron units) assigned to the carbon C (+0.72) and the oxygen O (−0.36) atoms (Maurin et al 2005a). Both the adsorbate-zeolite framework and adsorbate-adsorbate repulsion-dispersion interactions were modeled using Lennard-Jones potentials with our previous parameters which successfully reproduced the adsorption properties of various Faujasite forms (Maurin et al 2005b). Due to the presence of the proton in STA-7, the simulations required an additional contribution to the forcefield, able to reproduce the interactions between these protons and the carbon dioxide.…”

Gas Storage in Nanoporous Materials

“…Similar results for silicalite were obtained independently by other researchers who also investigated other siliceous zeolites (BEA and FAU) and uncovered an interesting trend. [136,137] Zeolite beta was chosen as a direct comparison to silicalite and both samples were considered approximately neutral frameworks so any difference is attributed solely to changing the framework topology. Beta adsorbs more CO 2 than silicalite (explained by the more open system); however, silicalite has higher initial heats of adsorption due to a more confined pore system.…”

Highly Stable Amine-modified Mesoporous Silica Materials for Efficient CO2 Capture

“…Among various chemical absorbents, metal oxides [9][10][11][12], Li-containing zirconates [13][14][15][16][17] and poly-ionic liquids [18,19] have been investigated. Numerous studies have explored methods of physisorption using functionalized/modified nanoporous solids for the abatement of CO 2 , for examples, microporous zeolites [20][21][22][23][24][25][26], activated carbons [27][28][29], porous coordination polymers or organic nanostructure materials [30][31][32]. However, these materials normally exhibit low CO 2 adsorption capacity (typically smaller to the benchmark value of ca.…”