Binary phase behavior and aggregation of dilute methanol in supercritical carbon dioxide: A Monte Carlo simulation study

Abstract

Configurational-bias Monte Carlo simulations in the Gibbs and isobaric-isothermal ensembles using the transferable potentials for phase equilibria force field were carried out to investigate the thermophysical properties of mixtures containing supercritical carbon dioxide and methanol. The binary vapor-liquid coexistence curves were calculated at 333.15 and 353.15 K and are in excellent agreement with experimental measurements. The self-association of methanol in supercritical carbon dioxide was investigated over a range of temperatures and pressures near the mixture critical point. The temperature dependence of the equilibrium constants for the formation of hydrogen-bonded aggregates (from dimer to heptamer) allowed for the determination of the enthalpy of hydrogen bonding, DeltaHHB, in supercritical carbon dioxide with values for DeltaHHB of about 15 kJ mol(-1) falling within the range of previously proposed values. No strong pressure dependence was observed for the formation of aggregates. Apparently the decrease of the entropic penalty and of the enthalpic benefit upon increasing pressure or solvent density mostly cancel each other's effect on aggregate formation.

Ab initio molecular dynamics investigations of structural, electronic and dynamical properties of water in supercritical carbon dioxide

“…closely resemble the conditions [37] for the presence of a hydrogen bonded complex. Thus, the local ordering of CO 2 molecules around heavy water indicates the possibility of existence of both EDA and hydrogen bonded moieties.…”

“…In order to identify the peak at 4.0 Å, we employ the standard geometric criteria [37] to define the hydrogen bond between D 2 O and CO 2 . These include conditions on the distance between the oxygen atoms, between D W and O C , as well as on the hydrogen bond angle.…”

Molecular motility and affinity of expanded carbon dioxide+ketone systems analyzed by molecular dynamics simulations

“…To study the solution structure, Cabaco et al studied CO 2 + ethanol and acetone mixtures using Raman spectroscopy [15] and Stubbs and Siepmann studied CO 2 + methanol mixtures using Monte Carlo simulations [16]. The mobility was studied by Funazukuri et al, who reported binary diffusion coefficients in CO 2 + ketone mixtures [17].…”

Prediction of the bubble point pressure for the binary mixture of ethanol and 1,1,1,2,3,3,3-heptafluoropropane from Gibbs ensemble Monte Carlo simulations using the TraPPE force field

“…These exhibit the typical behavior for strongly hydrogen bonding system with preferential aggregation. [51][52][53] The oxygen-hydrogen and oxygen-oxygen RDFs have pronounced and sharp peaks at the hydrogen bonding distances of 1.8 and 2.8Å, respectively. The RDFs also shown strong second peaks.…”