Fluid phase equilibria of the reacting mixture in the dimethyludcarbonate synthesis from supercritical CO2

摘要

In order to investigate the dimethyl carbonate synthesis from methanol and supercritical CO2, the thermodynamicudbehaviour of the reacting mixture, i.e. the quaternary methanol/CO2/DMC/water mixture, has to be known. TheudSRK equation of state with MHV2 mixing rules has been chosen to predict fluid phase equilibria in the reactor. Theudfirst part of this work is dedicated to the determination of binary interaction parameters, needed in the use of thisudmodel. These parameters are deduced from the fitting of experimental data concerning binary or ternary sub-systemsudexisting in the quaternary mixture. Literature data was used for most of the binary sub-systems, but for the DMC/CO2 and DMC/water mixtures, specific experiments were carried out. The agreement between experimental and predicted fluid phase equilibria was found to be satisfactory. With a view to studying of the operating conditions for the reaction, the thermodynamic model was used to predict fluid phase equilibria in the reactor, by considering several hypotheticaludfeed ratios and conversions. This work shows that CO2 has to be used in large excess in order to be sure of running the reaction in a homogeneous fluid medium.