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 system crystallization was also studied. The measurements were performed in an optical high-pressure cell, fitted with sapphire windows and a magnetic stirrer using on-line gas chromatography. Phase separation was observed depending on the synthetic method. All mixtures exhibit separation into two liquid phases below an upper solution temperature for a given pressure and a given mole fraction. In each case the demixing temperatures rise with increasing pressure. The phase behaviour of the systems investigated corresponds to type II phase diagrams according to the classification of van Konynenburg and Scott showing separate liquid-liquid and liquid-gas critical lines.