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Pré-Publication, Document De Travail Année : 2022

Role of Electrical Charges on the Adsorption of Hydrogen: Something Old, Something New.

Résumé

The adsorption of H2 in zeolites by molecular simulations use, in many applications, single sphere model. Although this representation provides coherent results with ex- periments above 77K, below this temperature the usual hydrogen representation fails to reproduce experimental results. The disagreement can be associated to the interplay of the atomistic heterogeneity and the electric field produced by the zeolite faujasite. These aspects are generally excluded in classical force fields. For elucidating the influ- ence of these issues, we performed DFT simulations for the faujasite Na86X at 40K with and without guest hydrogen molecules for determining the electrical field generated by the zeolitic structure. Our results show that the electrical field of the host structure induces a dipole moment on the hydrogens of ≈0.32 D. This value was included in clas- sical Monte-Carlo simulations by using a dumbbell representation of H2. Despite the small dipole moment, the simulations revealed an enhancement of adsorbed molecules. The formation of a dipolar moment in the H2 suggests that at cryogenic temperatures the agreement with experiments passes through the use of polarizable models of H2.
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hal-03821307 , version 1 (19-10-2022)

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  • HAL Id : hal-03821307 , version 1

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M. Salazar, Jean-Marc Simon. Role of Electrical Charges on the Adsorption of Hydrogen: Something Old, Something New.. 2022. ⟨hal-03821307⟩
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