Liquid-Liquid Equilibrium for Ternary Systems of Polyoxymethylene Dimethyl Ethers plus o-Xylene + Water at 293.15 K

Polyoxymethylene dimethyl ethers (PODEn) are excellent diesel blending components which can eliminate exhaust gas emissions compared to conventional diesel. During the production process of PODEn from methanol and formaldehyde solution, the most important key is to find an appropriate phenomenon for the separation of water and formaldehyde from PODE3-6 in advance. In this work, ternary liquid-liquid equilibrium (LLE) data were determined at T = 293.15 K under atmospheric pressure for the following systems: PODE1 + o-xylene (OX) + water, PODE2 + OX + water, PODE3 + OX + water, and PODE4 + OX + water. Hand and Othmer-Tobias equations were utilized to confirm consistency of the experimental LLE data. The NRTL and UNIQUAC activity coefficient models were applied to correlate the experimental LLE data, and the corresponding binary interaction parameters and LLE phase diagrams were obtained. The results indicate that both NRTL and UNIQUAC models agree well with the experimental LLE data, whereas the NRTL model gives a better agreement than the UNIQUAC model for ternary (PODE1-4 + o-xylene + water) systems.