Electrochemical valorization of H2S in natural gas to sulfate under mild conditions
Chunyu Zhang, An-Zhen Li, Bo‐Jun Yuan, Xiang Liu, Y. Liu, Kejian Kong, Qiujin Shi, Yi-Xuan Zhang, Yiqi Luo, Shengnan Li, Hua Zhou, Haohong Duan
Abstract
H2S capture and valorization from polluted natural gas offer environmental and resource recovery benefits, but current approaches produce moderate-value sulfur with intensive carbon footprint. Herein, we develop an electrochemical deep oxidation method that converts H2S from polluted natural gas into value-added K2SO4 using in-situ cathodically generated H2O2. We first validate this concept using commercial H2O2 and then in-situ generated H2O2 in H-cell, revealing the importance of high H2O2 concentration for deep H2S oxidation, especially sluggish S2O32−-to-SO32− conversion. We then showcase its application potential in 4-cm2 and then 100-cm2 flow reactor with high interfacial H2O2 concentration and large current, with the latter achieving H2S removal (100,000 ppm to <15 ppm), >70% K2SO4 selectivity, and 100-h stable operation. Life-cycle assessment and techno-economic analysis confirm the strategy’s sustainability advantages and economic viability. We finally extend this method to produce a 1.4 wt% H2SO4 solution by modifying the flow reactor with a solid-electrolyte type. Capturing and valorizing H2S from waste gas is key for sulfur recovery. Here, the authors report an electrochemical deep oxidation method that converts H2S from polluted natural gas into value-added sulfate-containing products (K2SO4 or H2SO4) using in-situ generated H2O2 at cathode.