Application of an electrochemical membrane reactor to the thermochemical water splitting IS process for hydrogen production

The Bunsen reaction (SO₂ + I₂ + 2H₂O = H₂SO₄ + 2HI) in the thermochemical IS process to produce hydrogen was successfully employed using an electrochemical membrane reactor. H₂SO₄ and HI were concentrated in the anode side and the cathode side of the reactor, respectively. I₂ is the dominant bulk of the recycling chemicals in this process, and I₂ concentration at the outlet of the reactor was reduced ca. 93% by using this technique. The electric energy consumption for the reaction was about 50% smaller by reducing the concentration of I₂ indicating that the IS process can be operate efficiently at low I₂ concentration. The reaction was carried out for 4 h, and the HI concentration was increased by 26%. This amount was the same within 10% as the values calculated from the total loaded electricity. In order to decrease the overpotential at the anode side, small amount of HI was added to the anode side solution. The total voltage was reduced by 0.03 V by the addition of HI.