Capillary Phase Transitions of n-Alkanes in a Carbon Nanotube

The capillary phase transitions of n-alkanes confined in a carbon nanotube are simulated for the first time using the gauge-cell Monte Carlo method with the configurational-bias scheme. At a subcritical temperature, the coexisting vapor−liquid phases are determined from a Maxwell construction along the adsorption isotherm, which exhibits a sigmoid van der Waals loop, including stable, metastable, and unstable regions. The confinement of an n-alkane in a carbon nanotube decreases its critical temperature, increases its critical density, and narrows its binodal curve.