Liquid-liquid equilibrium for the quaternary system propionic acid + n-propanol + n-propyl propionate + water at 293.15, 313.15 and 333.15 K

• LLE and solubility for propionic acid – n-propanol – n-propyl propionate – water system were measured at 293.15–333.15 K.
• The LLE data for two ternary sub-systems with miscibility gap are presented.
• The LLE data have been correlated by using NRTL model.

Liquid-liquid equilibrium (LLE) for the quaternary system propionic acid + n-propanol + n-propyl propionate + water and for the ternary sub-systems propionic acid + n-propyl propionate + water and n-propanol + n-propyl propionate + water were studied at 293.15, 313.15 and 333.15 K and atmospheric pressure. Binodal surface in quaternary system and binodal curves in ternary systems were determined. Experimental LLE data were compared with the values calculated by NRTL models, these data are in good agreement.