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Electrochemical membrane separation of H 2 S from reducing gas streams
Author(s) -
Robinson Jeffrey S.,
Smith D. Scott,
Winnick Jack
Publication year - 1998
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690441006
Subject(s) - cathode , anode , non blocking i/o , hydrogen , chemistry , electrochemistry , molten carbonate fuel cell , sulfur , analytical chemistry (journal) , electrochemical cell , inlet , electrode , environmental chemistry , catalysis , biochemistry , engineering , mechanical engineering , organic chemistry
An improved electrochemical membrane was tested with simulated coal gas having concentrations from 25 to 4,500 ppm H 2 S. The process produces elemental hydrogen that enriches the process gas stream at the cathode and elemental sulfur vapor that emerges from the anode. Removal efficiencies average up to 90% at any inlet level; current efficiencies are near 100% at the high inlet concentrations, decreasing significantly at lower H 2 S levels as the competing reduction of H 2 O becomes more favored. Molten carbonate fuel cell (MCFC) materials can be used exclusively at the MCFC operating temperature of 650°C, with the low concentrations of H 2 S, including the NiO cathode. At concentrations higher than about 60 ppm the operating temperature must be lowered approximately 50°C to avoid melting of the sulfided nickel cathode.