A gas permeable membrane electrode for selective and durable H2S production from SO2

Abstract

Converting SO2 into H2S is of great importance in recovering sulfur from SO2 streams, and even across the sulfur chemistry. However, H2S will comproportionate with SO2, resulting in undesired sulfur deposition to impede SO2 reduction reaction. Herein, a new concept of electrolysis paradigm to produce H2S from SO2 was introduced, wherein a gas-permeable catalyst membrane (Au/PTFE) was designed to in situ synthesis and separate H2S from the electrolyte, avoiding sulfur deposition behavior. This catalyst membrane electrolysis demonstrates a good performance with H2S Faraday efficiency of 99.6 % and separation efficiency of 99.1 %, with superior operational stability (exhibiting 38-hours continuous electrolysis without sulfur deposition). Computational studies and spectroscopic results reveal that S0 is the key intermediate for H2S production from SO2. The in situ separation of H2S not only prevents the S0 formation but also helps to self-clean the catalyst surface.