HIGH-PRESSURE VLE IN ALKANOL PLUS ALKANE MIXTURES - EXPERIMENTAL RESULTS FOR N-BUTANE PLUS ETHANOL, PLUS 1-PROPANOL, PLUS 1-BUTANOL SYSTEMS AND CALCULATIONS WITH 3 EOS METHODS

Bubble point pressures and vapour-liquid critical points of n-butane + ethanol, n-butane + 1-propanol and n-butane + 1-butanol were measured in the temperature range 323-523 K in a high-pressure capillary glass tube apparatus, using the synthetic method. It is shown that the shape of the vapour-liquid critical curve changes systematically with the carbon number of the l-alkanol. In the system n-butane + ethanol absolute azeotropy is found. Modelling of VLE of alkane + alkanol systems has been performed using the hole quasichemical group-contribution model (HM), the APACT EOS, and the Stryjek-Vera modification of the PR EOS with the Wong and Sandler mixing rules (WS/PRSV). Apart from the mixtures studied experimentally in the present work some more alkanol + alkane systems at high and low pressures are considered to assess the models. The APACT EOS and the HM predict VLE with good accuracy over a wide range of pressures, whereas the predictions by the WS method are slightly worse.