Electrolysis of hydrogen sulfide in aqueous solutions and molten salts

An analysis of the chemical and electrochemical reactions in aqueous sulfide solutions indicated that the electrolysis of hydrogen sulfide in an alkaline solution will yield elemental sulfur and hydrogen without the passivation of the electrode if the ratio of NaOH to NaHS is properly controlled. On the basis of this analysis, the new electrolysis process is presented for the recovery of elemental sulfur and hydrogen gas from hydrogen sulfide. Experiments have successfully demonstrated that the electrolysis with a cation-selective membrane cell in the solution of equimolar NaOH:NaHS yielded elemental sulfur and hydrogen, as predicted theoretically.; Also, sodium tetrasulfide melt was investigated as a possible electrolyte for electrolysis of hydrogen sulfide in a molten salt. Voltammetric, chronoamperometric and chronopotentiometric studies indicated that the current was predominantly due to the reduction of the sodium polysulfide, and that the reaction mechanism of the polysulfide reduction was not affected by the presence of hydrogen sulfide.; A mathematical model is presented to determine the feasibility of using an electrolyzer similar to the molten carbonate fuel cell for the electrolysis of hydrogen sulfide in a molten salt. It was found that under the conditions assumed in the model, the current density is entirely controlled by the mass transport through the separator and the maximum current density would not exceed 10 MA/cm{dollar}sp2{dollar}, a value far less than that required for industrial application.