Simultaneous production of H2 and C2 hydrocarbons by gas phase electrocatalysis

This study reports, for the first time in literature, the possibility of simultaneously producing H2 and C2s hydrocarbons by using an anionic single chamber solid electrolyte cell of Pt/YSZ/Ag (working/solid electrolyte/counter) tested under a humidified CH4 atmosphere (no direct O2 feeding gas to the reactor). Hydrogen was mainly produced in the Pt working electrode under application of negative polarizations by a steam electrolysis process (H2O + 2e− → H2 + O2−). Simultaneously, the produced O2− ions were electrochemically pumped to the Ag counter electrode, leading to the production of C2s hydrocarbons (ethane and ethylene), via oxidative coupling of CH4 (CH4 + O2− → C2H4 + C2H6 + 2e−). The influence of the applied current, reaction temperature and feeding composition on the electrocatalytic performance of the cell was evaluated for both processes. It was found that the possibility of controlling the rate of O2− supply allows to control and optimize the production rate of the desired compounds (H2 and C2s) at varying the reaction conditions. In addition, the stability of the cell for long polarization times has been demonstrated under the optimal conditions for the production of both compounds.

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► A new single chamber solid electrolyte cell (Pt/YSZ/Ag) has been developed.
► It allows to produce H2 and C2 hydrocarbons from a humidified methane atmosphere.
► On the Pt electrode, steam is electrolyzed leading to the production of H2 and O2− ions.
► On the Ag electrode CH4 reacts with the O2− ions producing C2s hydrocarbons.
► This novel system may have multiple advantages for its further practical application.