Critical properties for the mixtures of ethanol and some biodiesel surrogates

Critical temperature T_c and critical pressure p_c of the mixtures of ethanol and biodiesel surrogates (ethanol + methyl butanoate, ethanol + ethyl propanoate, ethanol + methyl hexanoate, methyl butanoate+ ethyl propanoate and ethanol + methyl butanoate + ethyl propanoate) were measured via a flow method. A linear decrease in T_c and an increase in p_c of three binary mixtures can be observed with the increasing mole fraction of ethanol. Despite the mole fraction of ethyl propanoate increases, critical curves of the ternary mixture change almost linearly with the mole fraction of ethanol. Critical properties of the binary mixtures were interrelated with Redlich–Kister equations and PR-WS equations and predicted by He equations. Maximum AADs for T_c and p_c using Redlich–Kister equations are 0.08% and 0.65%. There is a great agreement between our experimental data and calculated values from two correlations for the critical parameters of ternary mixture.