Canadian Journal of Chemical Engineering, Vol.77, No.1, 78-84, 1999
The CO-catalyzed conversion of H2S to H-2 plus sulfur - Part 2. The thermal decomposition of COS
The pyrolysis of COS has been studied over the temperature range 300 to 750 degrees C using a variety of catalysts. The observed product distribution confirmed that two parallel reaction paths: 2 COS --> 2 CO + S-2 (1) and 2 COS --> CO2 + CS2 (4) are involved in the decomposition. The decomposition yield increased with rising temperature, accompanied a shift in selectivity. At temperatures lower than similar to 700 degrees C the disproportionation reaction 4 was predominant, whereas at temperatures higher than 700 degrees C, reaction 2 was favoured. In the high-temperature region (700 to 750 degrees C) it was possible to achieve full suppression of reaction 4 with added CSI. The pyrolysis of COS was also studied in a reactor packed with quartz chips without catalysts at high temperatures. Between 800 and 900 degrees C, up to 99% conversion (with respect to the thermodynamic limit) could be achieved, with the almost complete absence of the disproportionation reaction 4. The results point to the commercial potential in the two-step reaction sequence: [GRAPHICS] for the economic conversion of hydrogen sulfide to hydrogen and sulfur.