Dimethyl ether production from CO2 rich feedstocks in a one-step process: Thermodynamic evaluation and reactor simulation

The dimethyl ether (DME) direct production from CO2-rich feedstock has been evaluated from thermodynamic and fixed bed reactor simulation perspectives, in order to evaluate the potentialities of using CO2 as reagent in one-step DME synthesis. The thermodynamic model has been applied to perform a detailed sensitive analysis of DME synthesis process at temperature within the range 200–275 °C, pressures of 20–70 bar and inlet composition of H2/CO = 1–3 and CO2/CO = 0–2.5. The results show a stringent thermodynamics threshold in DME yield (DME yield < 30%), when the CO2/CO ratio is greater than 2 in the fed to the synthesis reactor. The results have been confirmed by the kinetic mathematical model and reactor simulation, which includes chemical reactions, heat transfer and pressure drop along the fixed bed reactor. The performed simulations point out the role of cooling fluid temperature and reactor pressure. Furthermore, the kinetic modeling, in agreement with the thermodynamic approach, evidences the negative effect of water formed during CO2 conversion and further steps. The proposed thermodynamic and kinetic insight states that water removal during CO2 conversion, for example by hydrophilic membrane, is a mandatory element to enable industrial production of DME in the framework of CO2 valorization.