A deep investigation of neo-pentane freeze-out in methane

The investigation of the phase equilibrium behaviour of the methane + neopentane system has attracted a lot of interest in recent years seeing that neopentane is one of the heaviest natural gas components, a characteristic that poses a risk of freeze-out for the natural gas liquefaction process. Despite its high triple-point temperature (256.6 K), the solubility of solid neopentane in liquid methane is expected to be relatively high (a few percent at LNG temperatures) according to recent works dealing with the measurement and prediction of the solid-liquid(-vapor) equilibrium behaviour of this mixture. However, experimental phase equilibrium data are only available at temperatures down to 200 K or below 125 K, meaning that information is still missing in the 125 K < T < 200 K range. The aim of this work is to enhance the understanding of the thermodynamic behaviour of the methane + neopentane system by further experimental results concerning the solid-liquid, solid-vapor, solid-liquid-vapor, and vapor-liquid equilibria between 100 K and 240 K. If the results presented in this work confirm that neopentane is quite soluble in the liquid phase, they also indicate that the liquefaction pressure should be carefully chosen since neopentane is poorly soluble in vapor methane.-