Electrochemical Nonoxidative Coupling of Methane in a Protonic Ceramic Electrolysis Cell

Nonoxidative coupling of methane (NOCM) is a promising way to produce C2 chemicals such as ethane and ethylene with high selectivity, but it is hindered mainly by the high operating temperature and severe carbon deposition on catalysts. To improve methane conversion at lower temperatures, an electrolyte-supported protonic ceramic electrolysis cell (PCEC) is fabricated for the electrochemical nonoxidative coupling of methane in this work. Sr2Fe1.575Mo0.5O6−δ-BaZr0.1Ce0.7Y0.2O3−δ composite anode with a three-dimensional nanofiber network structure is synthesized through an electrospinning process. Metallic Fe nanoparticles are in situ exsolved from the oxide matrix and anchored on the surface of the nanofibers, which promotes the activation and coupling of methane. The nonoxidative coupling of methane is also assisted by the external electric field. At 700 °C, the conversion of methane achieves 8.4% with a C2 yield of 3.5% at an applied voltage of 2.0 V, comparable to the performance of a conventional thermal catalytic process at about 1000 °C. The electrochemical methane coupling system exhibits a good durability of 200 h.