On the Calculation of Supercritical Fluid−Solid Equilibria by Molecular Simulation

Abstract

Methods and intermolecular potentials apt for the molecular simulation of solubilities of solids in supercritical fluids are briefly reviewed. As an illustrative example, the solubilities of naphthalene in supercritical carbon dioxide at 328.15 K are studied using an isotropic multipolar potential model. Upon using the Widom insertion method, a quantitative prediction of the experimental data is obtained. A further look at the calculations shows that the customary implementation of the method is tainted by the use of experimental information about the vapor pressure and density of the solid. If the actual properties (obtained via simulation) of the model solid are used, the equilibrium is, in this example, poorly described. Full-scale molecular dynamic simulations, which include both the solid and fluid phases, confirm the results. It is shown how an accurate description and modeling of the solute solid-phase properties is a prerequisite for the determination of the solubilities of solids in supercritical fluids.

SAFT-γ Force Field for the Simulation of Molecular Fluids. 1. A Single-Site Coarse Grained Model of Carbon Dioxide

“…Some common choices are based on the use of viscosity and diffusivity data, [58][59][60][61][62][63] a direct fit of the critical temperature and density, 20,64,65 or on an overall representation of single phase volumetric properties and fluid phase equilibria data. 66 Some of the available parameterizations for the LJ model of CO 2 are summarised in Table 1.…”

“…This may at first sight appear too crude an approximation since it is well known that simple spherically symmetric intermolecular potentials such as the LJ model cannot be used to capture the fluid phase equilibria of CO 2 with reasonable accuracy 20,22 (cf. Section A).…”

Molecular Simulation of CO2- and CO3-Brine-Mineral Systems

“…The Fluid-Solid equilibria (FSE) have attracted less attention, but have also provided interesting insights. Albo and Müller (2003) discussed the relevance of simulation methods and the choice of force field for the prediction of these equilibria. More recently, Péréz-Sanchez et al (2013)w analyzed the role of the quadrupole moment on the melting curve of dry ice up to 1000 MPa by comparing several popular force fields.…”

An AOT reverse micelle in a medium of supercritical carbon dioxide

“…At present, several models of carbon dioxide have been described in the literature [14][15][16][17][18][19][20][21][22][23][24]. The three following main principles of describing molecules may be distinguished among them:…”

“…• Simplified models that take into account the qua drupole moment [19][20][21][22]. One force center of inter action corresponds to the three atom CO 2 molecule.…”