Kinetic analysis on the production of dimethyl ether (DME)

Among the possible strategies under consideration to address the ongoing energy transition, power-to-liquid (P2L) processes are gaining increasing interest as they typically combine the exploitation of green hydrogen with CO₂ feedstock, captured within the framework of carbon capture and utilization (CCU) systems, for the production of valuable products, such as chemicals and fuels. Among these, dimethyl ether (DME) is one of the most promising compounds, being a widely used intermediate chemical as well as an attractive alternative fuel and energy carrier. It can be produced via direct CO2 hydrogenation as well as through the formation of methanol as an intermediate. The former presents potential advantages for an optimized separation section, whereas the latter is grounded on well-established technologies for catalysts. In this context, a preliminary assessment was devoted to the identification of the most promising layout for reactors suitable for the direct conversion of CO2 to DME. A comparison with the traditional two step process was performed. Besides, this work developed a kinetic model for the representation of the main catalytic reactions that govern the production of DME, through the solution of mass and energy balances. The overall kinetic model was validated using dedicated software tools (i.e., Cantera), on the basis of experimental data available in the literature. This analysis, focused on the evaluation of the performance of the direct (single-pot) DME production process, provides an effective additional tool for assessing process feasibility and for identifying the most relevant operating conditions for the direct production of DME.