In Step 2, the H 2 S generated in step 1 and any CS 2 present (e.g., from reactions 1b or 1d) are decomposed through reaction with excess SO 2 . This reaction, commonly known as the Catalytic Claus process, has favorable reaction conditions around 600 K. For Step 3, 2/3 of the elemental S produced through reactions 2a or 2b is recycled for use in the sulfur-reforming step (Step 1), while the remaining 1/3 is added to sulfuric acid under reflux conditions up to 337 °C to form SO 2 according to reaction 3a. Reaction 3a becomes favorable above ~100 °C and proceeds rapidly in concentrated sulfuric acid. Finally, in Step 4, 1/3 of the generated SO 2 is recycled for use in the Catalytic Claus step, while the remainder is sent to an electrochemical cell. This SO 2 electrochemical cell regenerates aqueous H 2 SO 4 in the anode compartment and the H 2 product around the cathode according to reaction 4a.