Experimental determination and modeling of the phase behavior for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide

• New experimental data are reported for the CO2–methanol–DMC–water VLE.
• The CPA equation of state was extended to mixtures relevant to the DMC synthesis.
• Predictions for the phase behavior of ternary and quaternary mixtures were obtained.
• The CPA model is capable of predicting the phase behavior of such complex systems.
• The suggested modeling approach could facilitate the optimization of the process.

This study focuses on the investigation of the phase behavior of mixtures relevant to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The bubble points of corresponding quaternary mixtures of varying composition were experimentally determined. The Cubic-Plus-Association (CPA) equation of state was applied to model the phase behavior of the experimentally studied systems. In this regard, the CPA binary interaction parameters were estimated based on experimental data for the corresponding binary systems available in the literature, and subsequently the model was applied to predict the phase behavior of the multicomponent systems. It was shown that CPA is capable of predicting the phase behavior of such complex systems containing polar and associating components at high temperatures and pressures with reasonable accuracy considering the non-ideality of such mixtures. The results reveal P–T regions where the system can exist in one single phase and where it is multiphase, which can be used for further optimization not only of the chemical reaction itself but also subsequent product separation processes.

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