title: Adsorption of CO2, N2, and CH4 in Cs-exchanged chabazite: a combination of van der Waals density functional theory calculations and experiment study.
abstract: The crucial role of dispersion force in correctly describing the adsorption of some typical small-size gas molecules (e.g., CO2, N2, and CH4) in ion-exchanged chabazites has been investigated at different levels of theory, including the standard density functional theory calculation using the Perdew, Burke, and Ernzerhof (PBE) exchange-correlation functional and van der Waals density functional theory (vdWDFT) calculations using different exchange-correlation models - vdW_DF2, optB86b, optB88, and optPBE. Our results show that the usage of different vdWDFT functionals does not significantly change the adsorption configuration or the profile of static charge rearrangement of the gas-chabazite complexes, in comparison with the results obtained using the PBE. The calculated values of adsorption enthalpy using different functionals are compared with our experimental results. We conclude that the incorporation of dispersion interaction is imperative to correctly predict the trend of adsorption enthalpy values, in terms of different gas molecules and Cs(+) cation densities in the adsorbents, even though the absolute values of adsorption enthalpy are overestimated by approximate 10 kJ/mol compared with experiments.
authors.affiliation: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Barton, Australian Capital Territory 2600, Australia.
authors.forename: Jin
authors.initials: J
authors.lastname: Shang
authors.affiliation: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Barton, Australian Capital Territory 2600, Australia.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Barton, Australian Capital Territory 2600, Australia.
authors.forename: Ranjeet
authors.initials: R
authors.lastname: Singh
authors.affiliation: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Barton, Australian Capital Territory 2600, Australia.
authors.forename: Penny
authors.initials: P
authors.lastname: Xiao
authors.affiliation: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Barton, Australian Capital Territory 2600, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Danaci
authors.affiliation: Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Jefferson Z
authors.initials: JZ
authors.lastname: Liu
authors.affiliation: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Barton, Australian Capital Territory 2600, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Webley