This work is framed within the 8th International Fluid Properties Simulation Challenge
(IFPSC), with the aim of assessing the capability of molecular simulation methods
and force fields to accurately predict adsorption in porous media for systems of relevant
practical interest. The current challenge focuses on predicting adsorption isotherms of
n-perfluorohexane in the certified reference material BAM P109 standard activated carbon.
A temperature of T = 273 K and pressures of p/p0 = 0.1, 0.3, and 0.6 relative to
the bulk saturation pressure p0 (as predicted by the model) are the conditions selected
in this challenge. In our methodology we use coarse-grained (CG) intermolecular models
and a top-down technique where an accurate equation of state (EoS) is used to link the
experimental macroscopic properties of a fluid to the force-field parameters. The stateof-the-art
version of the statistical associating fluid theory for potentials of variable range
as reformulated in the Mie group contribution incarnation (SAFT-γ Mie) is employed
here. The parameters of the SAFT-γ Mie force field are estimated directly from the
vapour pressure and saturated liquid density data of the pure fluids using the EoS, and
further validated by molecular dynamic simulations. The coarse-grained intermolecular
potential models are then used to obtain the adsorption isotherm kernels for argon, carbon
dioxide, and n-perfluorohexane in graphite slit pores of various widths using Grand
Canonical Monte Carlo (GCMC) simulations. A unique and fluid-independent pore size
distribution (PSD) curve with total micropore volume of 0.5802 cm3/g is proposed for the
BAM P109. The PSD is obtained by applying a non-linear regression procedure over the
adsorption integral equation to minimise the quadratic error between the available ex-perimental adsorption isotherms for argon and carbon dioxide and purpose-built GCMCkernels.
The predicted adsorption levels of n-perfluorohexane at 273K in BAM P109 are
72.75±0.01, 73.82±0.01 and 75.44±0.05 cm3/g at STP conditions for p/p0 = 0.1, 0.3,
and 0.6, respectively.