Platinum Metals Rev., 1997, 41, (1), 32
Sulfur Removal by Platinum
Petroleum and natural gas contain sulfur, and its removal by hydrodesulfurisation produces hydrocarbons and hydrogen sulphide, which may be removed via the Claus process. In the Claus process, sulfur is recovered from hydrogen sulfide in a two-stage process in which hydrogen sulfide is mixed with oxygen to yield water and sulfur dioxide, the latter then reacts with more hydrogen sulfide to produce sulfur and water.
Researchers from McGill University, Canada, have now produced a homogeneous platinum catalyst which mimics the Claus process (A. Shaver, M. El-khateeb and A.-M. Lebuis, Angew. Chem., Int. Ed. Engl ., 1996, 35, (20), 2362–2363). They report on the reaction of cis -[(PPh3)2Pt(SH)2] (cis-2) with sulfur dioxide, to produce [(PPh3)2PtS3O] (1). Both complexes catalyse the Claus reaction.
The catalytic cycle proposed for this reaction involves adduct formation between cis-2 and sulfur dioxide, followed by sulfur dioxide insertion into the sulfur-hydrogen bond. Elimination of water produces (1), which reacts with hydrogen sulfide to cleave the platinum-sulphur bonds and regenerate cis-2 . The other cleavage product was not detected, and may be a key intermediate in the process.