PHASE-SEPARATION IN BINARY-MIXTURES OF TRIFLUOROMETHANE WITH PROPANE,BUTANE AND XENON AT LOW-TEMPERATURES BETWEEN 200 AND 280 K, AND AT PRESSURES UP TO 200 MPA

Liquid-liquid equilibria in the three binary systems CHF3 + C3H8, CHF3 + C4H10 and CHF3 + Xe were investigated in the low-temperature range from 200 to 280 K and at pressures from 10 to 200 MPa. In the Xe syste m crystallization was also studied. The measurements were performed in an optical high-pressure cell, fitted with sapphire windows and a mag netic stirrer using on-line gas chromatography. Phase separation was o bserved depending on the synthetic method. All mixtures exhibit separa tion into two liquid phases below an upper solution temperature for a given pressure and a given mole fraction. In each case the demixing te mperatures rise with increasing pressure. The phase behaviour of the s ystems investigated corresponds to type II phase diagrams according to the classification of van Konynenburg and Scott showing separate liqu id-liquid and liquid-gas critical lines.