ELECTROCHEMICAL MEMBRANE SEPARATION OF H2S FROM REDUCING GAS STREAMS

An improved electrochemical membrane was tested with simulated coal ga s having concentrations from 25 to 4,500 ppm H2S. The process produces elemental hydrogen that enriches the process gas stream at the cathod e and elemental sulfur vapor that emerges from the anode. Removal effi ciencies aver-age up to 90% at arty inlet level; current efficiencies are near 100% at the high inlet concentrations, decreasing significant ly at lower H2S levels as the competing reduction of H2O becomes more far;ol ed. Molten carbonate fuel cell (MCFC),I materials can be used e xclusively at the MCFC operating temperature of 650 degrees C, with th e low concentrations of H2S, including the NiO cathode. Ar concentrati ons higher than about 60 ppm the operating temperature must be lowered approximately 50 degrees C to avoid melting of the sulfided nickel ca thode.