SO2 carry-over and sulphur formation in a SO2-depolarized electrolyser

SO₂-depolarized electrolysis (SDE) is considered as one of the most efficient hydrogen production methods. To maximize H₂ production in SDE, the phenomena occurring in the cell need to be understood and controlled. In this work, electrochemically driven SO₂ carry-over and elemental sulphur formation in cathode space are analysed by various methods: electrochemical, titration and photon correlation spectroscopy (PCS) under different conditions during SDE operation. The results indicate that SO₂ carry-over is a fast process in an operating SDE and is difficult to control with only working parameter optimization. The PCS method provides SO₂ carry-over information at early stages compared to other methods. Moreover, PCS might be further implemented as an in situ method for SDE system control.