On the Effect of the Reaction Medium on the HydroClaus Process: A Novel Sustainable H2S Valorization Strategy

Hydrogen sulfide (H2S) is becoming a critical issue to manage, due to the increasing sulfur content in the processed gas together with the stricter environmental regulations. Novel alternatives are being developed for the H2S abatement and conversion to valuable chemicals. Among them, the HydroClaus process, patented by Eni S.p.A., deserves attention. This technology aims at converting H2S and SO2 into a hydrophilic mixture of sulfur and sulfur-rich compounds, polythionates, to be used as a fertilizer. An improved configuration for an efficient water management is proposed in this work. The process operability has been demonstrated at the bench scale, through an ad hoc experimental campaign. For the technology scale-up, a flowsheet has been set up and its performances have been assessed in terms of heat and material balances and CO2 emissions. Results reveal that the modified HydroClaus process can be a valid solution for an effective H2S valorization, also considering that no direct CO2 emissions are released. Moreover, since only electric power is required, a further reduction of the indirect CO2 emissions is expected, if renewable sources can be exploited for this purpose.