H2S removal units with liquid redox

H2S removal with liquid redox system by Pietro Fiorentini is based on a reduction-oxidation reaction carried out in liquid phase, that converts hydrogen sulfide present in sour gas to elemental sulphur and water. The liquid phase reaction is enhanced by a solution of iron which is held in solution by organic chelating agents. The iron in the solution oxidizes the hydrogen sulfide to sulfur. The spent redox agent in the solution is then circulated to an oxidizer (reaction with air) and regenerated to be reused. Process forms solid sulphur particles that can be easily filtered from the solution.​
Liquid redox is commonly used when the gas stream has a high content of hydrogen sulfide, thus solid bed technology is not feasible. This technology is useful also when low gas flowrates result in a non-economic application of direct oxidation processes such as Claus.