Catalytic hydrogen sulfide conversion in liquid sulfur

Catalytic conversion of H2S to elemental sulfur was investigated in liquid sulfur as a new technology for low-tonnage sulfur recovery from H2S-containing gas streams. The objectives focused on developing a mechanistic understanding of catalyzed H2S conversion chemistry in liquid sulfur using both O2 and SO2 in the feed and subsequently optimizing the reaction kinetics and catalytic activities as a function of the experimental conditions. Unsupported FeO(OH) acted primarily as a scavenger for bulk H2S removal, with the sulfided Fe xS(OH) maintaining only low, steady-state catalytic activity. However, FexS(OH) showed high activity for SO 2 production via the reaction of liquid sulfur with O2. SO 2 production kinetics were first-order with respect to the O2, with specific activities over FexS(OH) being much higher than that over gamma-Al2O3. Utilizing the SO 2 production over FexS(OH), a dual catalyst regime (gamma-Al2O3/FexS(OH)) in liquid sulfur produced 97.0 % H2S conversion to elemental sulfur at 296 kPa through a combination of direct oxidation and the Claus reaction. Subsequent investigations at high pressure with gamma-Al2O 3/FechiS(OH) in liquid sulfur using a stainless steel stirred-tank reactor showed 99.6 % H2S conversion to elemental sulfur at 1813 kPa using a non-stoichiometric 1.33 % H2 S: 1.16 % O2 (balance N2) feed. High selectivity to sulfur was also measured using high concentration H2S/O 2 feed gases in the presence of CH4 and CO2, and using an industrially modelled sulfur-pit feed gas. Overall, catalytic H 2S conversion in liquid sulfur was shown to be an effective strategy for low-tonnage sulfur recovery from industrial sour gas streams.