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Modular Systems in Natural Gas and Hydrogen Industries
Published in Yatish T. Shah, Modular Systems for Energy and Fuel Recovery and Conversion, 2019
In the SI process, water thermally dissociates at significant rates into hydrogen and oxygen at temperatures approaching 400oC. The SI process consists of three primary chemical reactions that accomplish the same result at much lower temperatures [36,103–114]. The process involves the decomposition of sulfuric acid and hydrogen iodide, and regeneration of these reagents using the Bunsen reaction. Process heat is supplied at temperatures greater than 800°C to concentrate and decompose sulfuric acid. The exothermic Bunsen reaction is performed at temperatures below 120°C and releases waste heat to the environment. Hydrogen is generated during the decomposition of hydrogen iodide, using process heat at temperatures greater than 300°C. The product hydrogen gas is produced at a pressure of 4.0 MPa. Modular operation allows the insertion of new innovations in this process [1,36,114,109–113].
Next-generation technology starts with iodine
Published in Tatsuo Kaiho, Iodine Made Simple, 2017
Basic steps in the IS method are shown in the diagram. The IS method is comprised of three processes, namely sulfuric acid decomposition in which oxygen is obtained through thermal decomposition of sulfuric acid at approximately 850°C, hydrogen iodide decomposition where hydrogen is obtained through thermal decomposition of hydrogen iodide at 400–500°C, and the Bunsen reaction where the iodine, sulfurous acid gas, and water obtained from the above thermal decomposition is converted to hydrogen iodide and sulfuric acid at around 100°C. From this, hydrogen can be produced with just water and thermal energy.
Water Dissociation Technologies for Hydrogen
Published in Yatish T. Shah, Water for Energy and Fuel Production, 2014
This cycle has been investigated by several research teams because the cycle involves only liquids and gases. General Atomics has discovered that it is possible to separate two acids in the presence of excess iodine and water. However, an efficient separation of HI from water and excess iodine at the outcome of Bunsen reaction still remains an issue. The high-temperature decomposition of acids is also an issue. The cycle was successfully tested in Japan to produce 451 of hydrogen. It was also tested in France at the capacity of 50 1/h [107,129,130].
Parametric analysis of water electrolysis by dual electrolytes and cells
Published in International Journal of Green Energy, 2019
Ming-Yuan Lin, Lih-Wu Hourng, Kai-Lin Chiou
Figure 3a shows IV diagrams for single and dual cells to investigate the effect of ion-exchange membrane on the performance of water electrolysis. As the applied voltage is increased, the corresponding current density is increased for three cases. According to the related studies, the effect of electrolyte with KOH is better than that with H2SO4, and using KOH will not produce Sulfide. As the result, KOH is chosen for the single electrolyte experiment without PEM. The electrochemical investigations of as-prepared composites were carried in two electrolytes such as KOH and H2SO4 for comparison. KOH have good performance in aspect of capacitance. (Periasamy et al. 2019). In chemical cycles to produce hydrogen, both the H2S splitting cycle and the sulfur-iodine water splitting cycle share the Bunsen reaction and HI decomposition. Therefore, they have to overcome the same challenges in the technology development, one of them being the complex and difficult separations of the mixed hydroiodic acid and sulfuric acid solution after the Bunsen reaction (Wang et al. 2012; Zhang et al. 2018).