INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
artículos
Título:
Comparative Study of Methane Adsorption on Graphite
Autor/es:
ALBERTO G. ALBESA, JORGE L. LLANOS, AND JOSÉ L. VICENTE
Revista:
LANGMUIR
Referencias:
Año: 2008 p. 3836 - 3840
ISSN:
0743-7463
Resumen:
To study methane adsorption on graphite in a wide range of coverages
and temperatures, we compare experimental results with Monte Carlo
simulations (MCSs) of the grand canonical ensemble (GCE) and mean-field
approximation (MFA) of the lattice gas model (LGM). MCSs were performed
by employing two models for the substrate description; we utilized
Steele's 10-4-3 analytical potential, and as a second approach, we
represented the graphite surface as composed of several graphene layers
(at the atomic level). We obtained adsorption isotherms and density
profiles that confirm a layer-by-layer mechanism at low temperatures;
the later results in the analytical model having a denser condensed
phase than the atomistic one. LGM calculations show a close-packed
lattice configuration and also allow us to describe the adsorption
mechanism changes with temperature. The isosteric heat of adsorption
that was found was approximately 13 kJ/mol. We can also conclude that,
in spite of the greater computational cost, the atomistic model could
be employed for surfaces that are not necessarily homogeneous and
beyond the low-pressure range that are not covered by the simple, fast
description given by the analytical model.