Investigation of the Phase Equilibria of CO2/CH3OH/H2O and CO2/CH3OH/H2O/H2 Mixtures

Abstract

The storage of excess electricity from renewable energy sources is nowadays a crucial topic. One promising technology is the methanol (CH3OH) synthesis from H2/CO2 mixtures. The achievable one-pass conversion is limited within this exothermic equilibrium reaction. A possibility to overcome this limitation would be withdrawing CH3OH and H2O from the gas phase through in situ condensation under reaction conditions. In this work, the phase equilibrium for mixtures representative for different degrees of conversion was studied. A view cell was employed to determine systematically the single- and two-phase regimes and obtain phase envelopes for mixtures of H2, CO2, CH3OH, and H2O from 66 to 305 °C and 61 to 233 bar. Furthermore, the densities in the single-phase area were determined and quantified by an empirical model.