The effect of atomic point charges on adsorption isotherms of CO(2)and water in metal organic frameworks
authors Sladekova, K; Campbell, C; Grant, C; Fletcher, AJ; Gomes, JRB; Jorge, M
nationality International
journal ADSORPTION-JOURNAL OF THE INTERNATIONAL ADSORPTION SOCIETY
author keywords Molecular simulation; Point charges; Carbon capture; Water adsorption; Metal-organic frameworks; Open metal sites
keywords MOLECULAR ELECTROSTATIC POTENTIALS; STRUCTURE-PROPERTY RELATIONSHIPS; CARBON-DIOXIDE SEPARATION; TOTAL-ENERGY CALCULATIONS; MONTE-CARLO SIMULATIONS; FORCE-FIELD; POPULATION ANALYSIS; POROUS MATERIALS; GAS-ADSORPTION; CO2 ADSORPTION
abstract The interactions between metal-organic frameworks (MOFs) and adsorbates have been increasingly predicted and studied by computer simulations, particularly by Grand-Canonical Monte Carlo (GCMC), as this method enables comparing the results with experimental data and also provides a degree of molecular level detail that is difficult to obtain in experiments. The assignment of atomic point charges to each atom of the framework is essential for modelling Coulombic interactions between the MOF and the adsorbate. Such interactions are important in adsorption of polar gases like water or carbon dioxide, both of which are central in carbon capture processes. The aim of this work is to systematically investigate the effect of varying atomic point charges on adsorption isotherm predictions, identify the underlying trends, and based on this knowledge to improve existing models in order to increase the accuracy of gas adsorption prediction in MOFs. Adsorption isotherms for CO(2)and water in several MOFs were generated with GCMC, using the same computational parameters for each material except framework point charge sets that were obtained through a wide range of computational approaches. We carried out this work for 6 widely studied MOFs; IRMOF-1, MIL-47, UiO-66, CuBTC, Co-MOF-74 and SIFSIX-2-Cu-I. We included both MOFs with and without open metal sites (OMS), specifically to investigate whether this property affects the predicted adsorption behaviour. Our results show that point charges obtained from quantum mechanical calculations on fully periodic structures are generally more consistent and reliable than those obtained from either cluster-based QM calculations or semi-empirical approaches. Furthermore, adsorption in MOFs that contain OMS is much more sensitive to the point charge values, with particularly large variability being observed for water adsorption in such MOFs. This suggests that particular care must be taken when simulating adsorption of polar molecules in MOFs with open metal sites to ensure that accurate results are obtained.
publisher SPRINGER
issn 0929-5607
isbn 1572-8757
year published 2020
volume 26
issue 5
beginning page 663
ending page 685
digital object identifier (doi) 10.1007/s10450-019-00187-2
web of science category Chemistry, Physical; Engineering, Chemical
subject category Chemistry; Engineering
unique article identifier WOS:000541911300001
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journal impact factor 1.949
5 year journal impact factor 2.639
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