HIGH-PRESSURE PHASE-EQUILIBRIA IN THE SYSTEMS METHANE PLUS PHENANTHRENE AND METHANE PLUS 1-PHENYLDODECANE UP TO 400 MPA

In this paper, experimental data on the high-pressure phase behaviour of the systems methane + phenanthrene and methane + 1-phenyldodecane a re presented. For both systems vapour-liquid, solid-fluid, and solid-l iquid-vapour equilibrium data were determined. The experiments were ca rried out for various mixtures covering almost the whole composition r ange. The temperature range investigated was from 360 to 460 K for the methane + phenanthrene system and from 260 to 400 K for the methane 1-phenyldodecane system. The maximum pressures exerted on the samples were dependent on the equipment used, either 200 or 400 MPa. The seco nd critical endpoint (s + 1 = g), which is the pressure maximum of the three-phase curve (solid hydrocarbon + liquid + vapour), is, for the methane + phenanthrene system, located at a temperature T = 403.3 +/- 0.4 K, a pressure p = 358.9 +/- 1.5 MPa, and a mole fraction of phenan threne in the critical fluid phase x = 0.126 +/- 0.009. The coordinate s of the second critical endpoint of the methane + 1-phenyldodecane sy stem were found to be T = 277.1 +/- 0.4 K, p = 148.0 +/- 0.6 mpa, and for the mole fraction of 1-phenyldodecane in the critical fluid phase x = 0.076 +/- 0.005. (C) 1997 Elsevier Science B.V.