Strategy for the Separation of the Mixture of Dimethyl Carbonate, Formaldehyde, and Water

Abstract

In this work, the separation of a mixture of dimethyl carbonate (DMC), formaldehyde, and water is studied. In our process, formaldehyde is first extracted using water as the entrainer, and then the azeotrope of DMC–water is separated by extractive distillation with ethylene glycol. To verify the feasibility of the process, the liquid–liquid equilibrium (LLE) data of the DMC–formaldehyde–water system was measured and the vapor–liquid equilibrium (VLE) data of the DMC–ethylene glycol system was also measured at 101.3 kPa. Moreover, the reliability of experimental tie-line data was checked with the Bachman, Hand, and Othmer–Tobias equations, and the thermodynamic consistency of the measured VLE data was verified by the Van Ness test and infinite dilution test. Finally, all the measured values were correlated with the nonrandom two-liquid (NRTL) model and universal quasi-chemical (UNIQUAC) model, and the binary interaction parameters were regressed.

Measurement and Thermodynamic Modeling of Liquid–Liquid Equilibrium Data for Ternary Systems (Water + Formaldehyde + Methyl Isobutyl Ketone/Cyclohexanone) at Different Temperatures

“…Comparison of triangular diagrams for this work and references: (red open square), water + formaldehyde + MIBK at 323.15 K, this work; (blue open square), water + formaldehyde + CYC at 323.15 K, this work; (open triangle), water + formaldehyde + dimethyl carbonate measured at 288.15 K by Song et al, from ref ; (open circle), water + methanol + biodiesel measured at 298.15 K by Santos et al, from ref .…”

“…In addition, the values of S and D in this paper compared with those of another extractant (dimethyl carbonate) determined by Song et al at 288.15 K under 101.3 kPa are plotted in Figures and . As seen from Figures and , the S and D of CYC are significantly better than dimethyl carbonate.…”

“…Partition coefficient ( D ) vs mass fraction of formaldehyde in the MIBK (or CYC) layer under 101.3 kPa: MIBK, (open square), 303.15 K; (red open circle), 313.15 K; (blue open triangle), 323.15 K; CYC, (solid square), 303.15 K; (red solid circle), 313.15 K; (blue solid triangle), 323.15 K; (upside down open triangle), dimethyl carbonate, from ref .…”

“…Figure 10 shows the obtained triangular diagrams for the systems (water + formaldehyde + MIBK/CYC) at 323.15 K, compared with literature results that were determined by Song et al 34 at 288.15 K under 101.3 kPa with another solvent (dimethyl carbonate). As seen from Figure 10, the two-phase area of the systems (water + formaldehyde + MIBK/CYC) is larger than that of the system (water + formaldehyde + dimethyl carbonate), indicating that MIBK and CYC have the largest operating range among the three solvents.…”