High-pressure phase equilibria of binary and ternary mixtures containing the methyl-substituted butanols

High-pressure VLE and VLLE for both the binary mixtures of the carbon dioxide–3-methyl-1-butanol and carbon dioxide–3-methyl-2-butanol and the ternary mixtures of the carbon dioxide–3-methyl-1-butanol–water, carbon dioxide–3-methyl-2-butanol–water and carbon dioxide–2-methyl-2-butanol–methanol were measured at 313.2 K. The phase equilibrium apparatus used in this work is of the circulation type in which the coexisting phases are recirculated, on-line sampled and analyzed. The critical pressures and corresponding mole fractions at 313.2 K were also carefully determined for two binary mixtures. Two water-containing ternary mixtures showed the liquid–liquid–vapor phase behavior over the range of pressure up to their critical point, while for a methanol-containing ternary mixture only two phases coexist at equilibrium. The binary equilibrium data were all reasonably well correlated with the Redlich–Kwong, Soave–Redlich–Kwong, Peng–Robinson, and Patel–Teja equations of state incorporated with eight different mixing rules; the van der Waals, Panagiotopoulos–Reid, and six modified Huron–Vidal mixing rules with UNIQUAC parameters.