An Electrochemical Claus Process for Sulfur Recovery

Electrochemical oxidation of H 2 S to give sulfur and water was achieved at 900°C using fuel cells possessing the general configuration stabilized ZrO 2 H 2 S , anode electrocatalyst La 0.89 Sr 0.11 MnO 3 Pt , O 2 air 8 w / o Y 2 O 3 or 5 w / o CaO where anode electrocatalysts experimentally investigated for promoting the subject oxidation reaction included WS 2 and the thiospinels CuNi 2 S 4 , CuCo 2 S 4 , CuFe 2 S 4 , NiCo 2 S 4 , and NiFe 2 S 4 . The predominant oxidizable electroactive species present in the fuel cell anode compartment was suggested to be hydrogen originating from the initial thermal dissociation of H 2 S ( H 2 S ⇌ H 2 + 1 / 2 S 2 ) at fuel cell operating temperatures. Rapid anode kinetics were found for the anodic reaction with the empirical trend for exchange currents ( i 0 ) per geometric area being found to be: NiFe 2 S 4 > WS 2 > CuCo 2 S 4 > CuFe 2 S 4 ≅ NiCo 2 S 4 > CuNi 2 S 4 .