Phase diagram studies of methanolH2OCO2 and acetonitrileH2OCO2 mixtures

Abstract The primary goal of this work was to identify one-phase regions of the phase diagrams for methanol/H 2 O/CO 2 mixtures and acetonitrile/H 2 O/CO 2 mixtures over the temperature range of 25°–100°C. These mixtures are expected to be useful for efficient separation methods that require polar solutes with fast mass transfer. We were therefore most interested in finding mixture compositions that contained significant quantities of H 2 O and CO 2 . For both ternary mixtures at high proportions of CO 2 , the single-phase region was defined by the onset of an upper critical solution temperature line. Methanol/CO 2 mixtures are markedly more miscible with H 2 O than acetonitrile/CO 2 mixtures.