Low temperature hydrolysis of carbonyl sulfide using γ-alumina catalysts

The hydrolysis of COS using alumina as catalyst in the temperature range 10–80°C is described in detail. The rate of COS hydrolysis is found to be approximately first order in [COS] but is significantly inhibited with increasing [H2O]. Addition of CO2 is also found to have an inhibiting effect on the rate of hydrolysis, but no marked effect is observed when additional H2S is present in the feedstock. The reaction in this temperature range is contrasted with the previous studies at higher temperatures and it is suggested that the reaction proceeds via reaction of adsorbed COS with surface hydroxyl groups on the alumina. Supporting evidence for this is provided from experiments in which water was not co-fed with COS, or the flow of water vapour was interrupted. In both cases, an initial increase in the rate of COS hydrolysis is observed. The rate of COS hydrolysis can be significantly enhanced by the addition of Fe, Co, Ni, Cu and Zn to the alumina.