Highly-efficient natural gas desulfurization and simultaneous H₂O₂ synthesis based on the electrochemical coupling...

Hydrogen sulfide (H₂S) generated by natural gas exploitation is a dangerous and harmful gas that needs to be purified. Electrochemical Natural Gas Desulfurization offers a promising way for H₂S purification and resource utilization in ambient conditions. However, poor energy efficiency and low resource value limit the prospective application in the industry. Herein, we propose a gas-liquid flow electrocatalysis system that couples H₂S oxidation and O₂ reduction processes to effectively recover sulfur and H₂O₂ with low energy consumption. Gas diffusion and mass transfer are accelerated by gas-liquid flow cells, which also significantly decrease the resistance. Besides, I^-/I₃^- redox pairs promote selective H₂S oxidation while inhibiting water decomposition, resulting in a 56% reduction in oxidation potential. Moreover, the surface proton concentration is elevated by employing a modified carbon gas diffusion electrode (GDE), which assists to maintains a high H₂O₂ faradic efficiency. The system is able to operate at a high current density of 102 mA/cm² at an E_cell voltage of 3.5 V, yielding S and H₂O₂ at rates of 60 mg cm^-2 h^-1 and 50 mg cm^-2 h^-1 respectively. A techno-economic model forecasts the effects of system efficiency and energy prices on operational costs and illustrates potential routes to a plant-gate levelized application in the petrochemical industry.