Fluid Phase Equilibria of Binary Mixtures of SF6 with Octane, Nonane, Hendecane, and Decahydronaphthalene,cis at Temperatures between 280 K and 440 K and at Pressures up to 140 MPa in Comparison to Mixtures of Hydrocarbons with CO2, CF4, and CHF3

Abstract

AbstractBinary mixtures of SF6 + octane, + nonane, + hendecane, and + decahydronaphthalene,cis were investigated up to 140 MPa. Measurements were performed according to the synthetic method using an optical high pressure cell. ‐ Going from SF6 + octane to SF6 + nonane the critical p(T)‐curves show a continuous transition between the type of liquid‐liquid (ll) phase equilibrium with upper critical solution temperatures (UCST) and the gas‐gas (gg) equilibrium of the 2nd kind. For the SF6 + n‐alkane systems there is a systematical shift of the high‐pressure branches of the critical curves of about 20 K to higher temperatures per CH2‐unit. The experimental results are discussed in comparison to computer calculations with two semiempirical equations of state. Solvent properties of SF6 are compared to those of CO2, CF4, and CHF3.