Conversion of CS2 and COS over alumina and titania under Claus process conditions: reaction with H2O and SO2

Catalytic conversion of CS2 in the Claus process using either alumina or titania has always been assumed to proceed via hydrolysis. Although this conclusion is supported by the results of this study, data reported here show that the high CS2 conversion activity of titania may be due, in part, to the reaction of CS2 with SO2, a process which proceeds almost quantitatively at 320°C. This reaction was also shown to have an appreciable rate at 250°C, suggesting that some of the CS2 conversion activity of titania at second Claus converter conditions may be due to reaction with SO2. COS was identified as an intermediate product of the reaction of CS2 with SO2. Although these studies confirmed that alumina promotes hydrolysis of CS2, the industrial observation that it is not as efficient a catalyst as titania for the conversion of CS2 may be due to the limited ability of alumina to promote reaction of CS2 with SO2.