Thermodynamic Analysis of Coupling aSOEC in Co-Electrolysis Mode with the Dimethyl Ether Synthesis

This work describes a thermodynamic model of an integrated system for the production of a syngas, via a solid oxide electrolysis cell (SOEC), coupled with a subsequent catalytic upgrading into dimethyl ether (DME). The proposed energy system has been investigated on a thermodynamic basis, including exergy analysis.The syngas composition required for the catalytic upgrading is strongly affecting the SOEC design. SOEC operating conditions have been chosen in order to reach an H-2/CO ratio close to 1 while avoiding carbon formation. The produced syngas from the SOEC is then pre-treated and DME is synthesized in a one-step reactor in which both methanol synthesis and dehydration occur. Two different plant configurations have been investigated including an ambient pressure and a pressurized system. The layout and operating parameters have been chosen in order to maximize the purity of the produced DME without affecting the overall efficiency and yield. The global heat demand has been assessed with the waste heat recovery method. In the optimal configuration, an improvement in the DME content of the final product is obtained, reaching a value of 99.8% in mass. Therefore, such configuration would allow the final product to be readily used for transportation applications.