Ethane Decomposition in a Molten Alkali Halide Electrochemical System

Ethane is a crucial feedstock to produce ethylene, which is a fundamental building block in the modern petrochemical industry. Yet, the steam cracking of ethane is an energy-intensive and high carbon dioxide emission process for ethylene production in industry. Herein, we present an effective and stable electrochemical method for ethane decomposition in a molten alkali metal halide salt system at 400–600 °C. As the ethane bubbles ascend through the molten column, the electrolysis of molten alkali chloride facilitates chlorination of ethane near the anode and the subsequent reduction by the liquid reactive alkali metal generated at the cathode or the solvated electrons formed. This process leads to the production of valuable chemicals such as hydrogen, ethylene, and carbon and also regenerates the alkali chloride. A systematic study was performed to unveil the key parameters that govern ethane decomposition performance. In a molten LiCl-NaCl-KCl electrolyzer at 1.5 A current and 550 °C temperature, the ethane decomposition exhibited ∼71% ethane conversion, ∼48% hydrogen selectivity, and ∼34% ethylene selectivity. Based on the experimental and theoretical studies, the C2H6 chlorination and the subsequent reduction by the liquid reactive Na can occur easily. In addition, the molten salt system uses earth-abundant materials. Further optimizing the system parameters and designs would facilitate scaling up. Overall, this electrochemical process offers a promising technology for the conversion of ethane into valuable products.