Novel aqueous chelating agents for catalytic oxidation of hydrogen sulfide to sulfur by air

Abstract

Six phosphorus-containing analogues of nitrilotriacetic acid (NTA) or ethylenedinitrilotetraacetic acid (EDTA) form stable Fe(III) complexes which have been tested as catalysts for the oxidation of hydrogen sulfide. Ligand 4, phosphonomethyliminodiacetic acid (NTAP), was found to be comparable with NTA in efficiency of catalytic activity such as the conversion of hydrogen sulfide to sulfur, half-life of ligand, consumption of ligand per kg of sulfur product. A quantitative analytical method of phosphorus-containing ligand in the absorbed solution has been successfully established by applying ³¹P-{¹H} NMR.

Keywords:

• Iron chelates
• Hydrogen sulfide
• Sulfur
• Nitrilotriacetic acid (NTA)
• Phosphonomethyliminodiacetic acid (NTAP)
• Cyclic voltammogram
• Catalytic oxidation

Acknowledgements

We are grateful to the U.S. Filter for financial support and Dr. J.A. Crayston (University of St Andrews) for assistance with the cyclic voltametry analysis.