SweetSulf™ is a redox process developed for high pressure natural gas applications. Its specific solid sulfur removal technology overcomes the foaming/plugging problems experienced with other types of redox processes. SweetSulf™ has been demonstrated on an industrial pilot plant operated with natural gas under 80 bar, at a Engie underground storage facility.

Process Scheme




Process Principle


Sour Gas is contacted with an aqueous redox solution which extracts the H2S and converts it into solid elemental sulphur.

Gas separation

Treated gas, free of H2S, is separated from the redox solution.

Solid separation

Solid sulphur is filtered under pressure on a cartridge filter which can be regenerated on stream.


The redox solution is depressurized and re-oxidized by contact with air.


  • SweetSulf™ process has been proven for high pressure operation with 6 760 hours of industrial pilot operation
  • SweetSulf™ can treat any composition of gas in the range of H₂S concentration below 5 000 ppm
  • H₂S outlet levels can go below 1 ppm
  • Economic application range 10 – 1 000 ppm H₂S in feed
  • CO₂ partial pressure limited to # 4 bar

Key Benefits

  • Selective H2S removal with direct conversion into solid elemental sulfur
  • Gas sweetening may be done at any pressure
  • Ambient temperature operation
  • High Pressure Filtration: no foaming, no risk of plugging
  • Flexibility, easy operation
  • Minimum solvent flowrates and pumping costs.
  • CAPEX and total costs can be 20 – 50% lower than for conventional processes for feed H2S levels between 10 and 1 000 ppm)