Effects of melting and ordering on the isosteric heat and monolayer density of argon adsorption on graphite

Ustinov, Eugene A. and Do, Duong D. (2013) Effects of melting and ordering on the isosteric heat and monolayer density of argon adsorption on graphite. Adsorption, 19 2-4: 291-304. doi:10.1007/s10450-012-9452-9


Author Ustinov, Eugene A.
Do, Duong D.
Title Effects of melting and ordering on the isosteric heat and monolayer density of argon adsorption on graphite
Journal name Adsorption   Check publisher's open access policy
ISSN 0929-5607
1572-8757
Publication date 2013-04
Year available 2013
Sub-type Article (original research)
DOI 10.1007/s10450-012-9452-9
Volume 19
Issue 2-4
Start page 291
End page 304
Total pages 14
Place of publication New York, United States
Publisher Springer
Collection year 2014
Language eng
Abstract The aim of this paper is to study the effects of temperature on the state of the adsorbed argon on an uniform graphite surface. We applied the kinetic Monte Carlo scheme to simulate adsorption over a very wide range of temperature, which allows us to model the vapor–solid, the vapor–liquid and the order–disorder transition of the monolayer. The main distinction of our methodology is that it accounts for the lattice constant change with loading in the case of formation of an ordered molecular layer by appropriately changing the simulation box size. To do this we enforced the equality of the tangential pressures obtained by the virial and thermodynamic routes, which corresponds to the minimum Helmholtz free energy of a system at a given number of molecules and volume. This criterion is a consequence of the Gibbs–Duhem equation. A significant result obtained by application of the new simulation method was a sharp contraction of the monolayer just after its completion and the onset of the second layer. It manifests itself in an additional heat release. We re-determined the 2D-melting and 2D-critical temperatures of the molecular layer of argon. We also analyzed the order–disorder transition above the 2D-melting and showed that it could occur at some temperatures above the 2D-critical temperature. In this case, a hexagonal lattice appears at a sufficiently large tangential pressure. The effects of loading on the lattice constant, the 2D-critical temperature of the order–disorder transition and the differential heat of adsorption are thoroughly discussed.
Keyword Kinetic Monte Carlo
Adsorption on graphite
Monolayer phase transition
Heat of adsorption
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2014 Collection
 
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