Low temperature removal of hydrogen sulfide from sour gas and its utilization for hydrogen and sulfur production

Abstract This investigation demonstrated the prospects for the development of chemical-electrochemical plants for the removal of hydrogen sulfide from sour gas and production of high quality hydrogen and sulfur at low temperatures. The anodic oxidation of sulfide ions, formed by scrubbing sour gas with sodium hydroxide and adjusting the pH of anolyte with more NaOH to a pH of nearly 14, produced polysulfide ions. In this cell the cathodic product was hydrogen, with the electrolyte in the cathode chamber being NaOH. The electrolyte in the anodic and the cathodic compartments was separated by an ion exchange membrane (Nafion). The sodium polysulfide was transferred to a separate chamber through which sour gas, at a high concentration (10–15 vol.%) of H2S, was passed. Crystalline sulfur was produced. The filtrate was mixed with the solution obtained by hydrogen sulfide scrubbing and returned to the electrolytic cell. Extremely pure hydrogen and sulfur were produced at a low cell voltage (Ecell = 1.0 V), and at a high current density (i = 300 mA cm−2).