Novel process concept for the production of H 2 and H 2SO 4 by SO 2-depolarized electrolysis

Anu Lokkiluoto*, Pekka A. Taskinen, Michael Gasik, Ilkka V. Kojo, Heljä Peltola, Michael H. Barker, Karl Heinz Kleifges

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    20 Citations (Scopus)


    Outotec open cycle (OOC) is a new low-energy process linking together production of hydrogen and sulfuric acid. While sulfuric acid is the world's most widely produced chemical by mass at approximately 200 Mt/a, the OOC gives the potential for making 4 Mt/a of hydrogen gas as a by-product. H 2SO 4 manufacture requires a source of sulfur dioxide. 30% of world production of H 2SO 4 is from the SO 2 by-product of pyrometallurgical processing of sulfur containing concentrates of metals such as copper, nickel and zinc. SO 2 can also be made by direct combustion of sulfur. In OOC, a divided electrochemical cell is used for SO 2-depolarized electrolysis of water. SO 2 is fed to the anolyte and converted to H 2SO 4, while hydrogen gas is produced at the cathode. On the industrial scale, the equipment will be in the form of a membrane electrolyzer assembly or stack. A case is described where the OOC would be connected to a pyrometallurgical plant smelting 1 Mt/a of nickel and copper concentrate, producing 1 Mt/a of H 2SO 4 and 20 kt/a of hydrogen.

    Original languageEnglish
    Pages (from-to)529-540
    Number of pages12
    JournalEnvironment, Development and Sustainability
    Issue number4
    Publication statusPublished - Aug 2012
    MoE publication typeA1 Journal article-refereed


    • Hydrogen production
    • Metals production
    • SO recovery
    • Sulfuric acid production


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