High-pressure H2S conversion and SO2 production over γ-Al2O3/FeχS(OH) in liquid sulfur

A stainless steel autoclave was used to investigate high-pressure catalytic H2S conversion to sulfur in a liquid-sulfur medium. Using the fundamental chemistry developed in earlier low-pressure conversion studies, the objective of this work was to investigate the use of high pressures for increasing overall H2S conversion to elemental sulfur. Using 1.55% H2S (balance N-2) the H2S scavenging activity of fresh FeO(OH) was found to increase with increasing operating pressures. Reaction of 1.55% H2S with 0.80% 02 (balance N2) over Fe chi S(OH) resulted in 87% H2S conversion to elemental sulfur at a reactor operating pressure of 6984 kPa (1000 psig). Incorporating dual-catalyst reaction conditions (gamma-Al2O3/Fe chi S(OH)), 99.6% H2S conversion to elemental sulfur was attained using a feed gas containing 1.33% H2S/1.16% O-2 (balance N-2) and a reactor operating pressure of 1813 kPa (250 psig). It is suggested that SO2 is generated by the iron catalyst and that H2S conversion occurs by the reaction of H2S With SO2, primarily over gamma-Al2O3. A concurrent, SO2 kinetics investigation demonstrated very high SO2 production activity over Fe chi S(OH) as compared to gamma-Al2O3. Finally, the dual-catalyst regime proved capable of maintaining high H2S conversions to elemental sulfur under higher H2S-content feed-gas conditions. Overall, higher operating pressures proved to be effective for increasing the total H2S conversion to elemental sulfur.