Hydrogen and sulfuric acid production by electrolysis with anodic depolarization by sulfurous anhydride

Practical aspects of improving the efficiency of water electrolysis with anodic depolarization by sulfurous anhydride in an electrolyzer with a solid polymeric electrolyte are discussed. Methods of reducing energy outlays for the production of hydrogen, for example, by altering the organization of the feed of sulfurous anhydride to the reaction zone, are proposed and implemented. This made it possible to remove restraints on the mass transfer of SO 2 , and reduce the overvoltage of the anodic reaction. An electrolyzer is developed and fabricated for the corresponding process with an overall effective electrode area of 12.25 cm 2 . A so-called mixed loop for the feed of sulfurous anhydride, which makes it possible to achieve the following energy characteristics of the electrolysis process is implemented: a cell voltage of 1 V at a current density of 2000 A/m 2 . The yield of hydrogen with respect to the current was 95%, and the energy outlays for the production of 1 m 3 of hydrogen were 2.5 kWh, which amounted to half that for traditional electrolysis. No irreversible degradation of the properties of the electrolyzer was observed during longevity tests over a period of 180 h.