Electrochemical removal of H 2S from hot coal gas: electrode kinetics

Abstract

The reaction kinetics attending the electrochemical reduction of H 2S in molten sulfide at 830°C are examined. A mixture of sodium and potassium sulfides, melting around 700°C is used throughout, as are graphite electrodes. Potential-step experiments show large exchange currents, of the order of 10 −1 A cm −2. The reaction rate is dependent on nearly the square-root of the H 2S pressure. The oxidation reaction, of sulfide to elemental sulfur, is zero-order in H 2S pressure. The results are in agreement with mechanisms found by others at lower temperatures. Melting points of several binary alkali sulfides were also determined.