The direct conversion of hydrogen sulfide to hydrogen and sulfur

The thermal noncatalytic decomposition of H2S has been investigated in the temperature range 1000-1200 degrees C, neat and admired with nitrogen or helium at a total pressure of one atm. It has been found that, contrary to earlier literature claims, the inhibiting effect of the back reaction, the reverse reaction between H-2 and S-i (i = 1-8) molecules to regenerate H2S, can be overcome by the use of readily attainable, sufficiently high gas flow rates. In agreement with thermodynamic predictions, the reaction has been shown to be temperature and H2S pressure dependent; the experimental conversion was found to increase with rising temperature and declining H2S pressure. At 1200 degrees C and one atm. H2S pressure the measured conversion was 35.6% corresponding to 97.5% of the thermodynamic Limit when a steady gas flow of 50 mL/min and residence time of 48 seconds were maintained. The highest experimental conversion, 65.8%, was obtained at the highest temperature, 1200 degrees C, and lowest pressure, 0.050 atm., employed. For optimum conversions under the present experimental conditions it was necessary to use a quartz reactor packed with quartz chips. Apparently, at 1200 degrees C the chips have no catalytic effect but serve as heat transfer agents. (C) 1998 International Association for Hydrogen Energy.