Solubility of methane in octamethylcyclotetrasiloxane: Experimental measurement and thermodynamic modeling

Abstract

Liquid storage is a potential method for low-pressure storage of natural gas. In this work, octamethylcyclotetrasiloxane (OMCTS) was selected as a solvent for methane storage. Experimental measurements were carried out in a Cailletet apparatus, according to the synthetic method, from low to high pressures. One hundred experimentally-measured phase equilibrium data points are presented for methane + OMCTS in the form of bubble-points. The pressure, temperature, and methane mole fraction ranges are (0.61–8.07) MPa, (287.73–368.25) K, and (0.0534–0.4038), respectively. Furthermore, phase equilibrium calculations based on the ϕ−ϕ approach were carried out to model the methane + OMCTS binary system. In this regard, the Peng-Robinson EoS (PR EoS), coupled with the classical van der Waals (vdW) mixing rule, was applied. The vdW mixing rule was used in three modes: a) with no binary interaction parameters (kij=0,lij=0), b) with one constant binary interaction parameter (kij=constant), and c) with one temperature-dependent binary interaction parameter (kij=a+bT). It was concluded that both modes (b) and (c) give accurate results for methane solubility in OMCTS, with AAD(MPa) values of 0.11 and 0.10, respectively.