Hydrogen thermochemical decomposition

Bishara, A., Salman, O.A., Khraishi, N., Marafi, A. 1987. Thermochemical decomposition of hydrogen sulfide by solar energy. Int J Hydrogen Energy 12 679-685. 

Brecher, L.E., S. Spewock, C.J. Warde (1977), The Westinghouse Sulfur Cycle for the Thermochemical Decomposition of Water , International Journal of Hydrogen Energy, Vol. 2, pp. 7-15, Pergamon Press. 

A special focus of the development regarding solar thermochemical processes is the high temperature endothermic decomposition of sulphuric acid. The solarisation of this step was part of the R D activities of the European project HYTHEC (HYdrogen THErmochemical Cycles) with an emphasis on components development and process improvement (Noglik, 2009). 

Research on methods of hydrogen production by thermochemical decomposition of water has been carried out in several laboratories with increasing interest during the last decade. 

Note 2 More efficient methods than electrolysis for obtaining hydrogen from water are under investigation. One of these is thermochemical decomposition. Another is photochemical decomposition by solar radiation, either directly or via a solar power generator. Photolytic decomposition of water with platinum catalyst has been achieved. Hydrogen can also be obtained by photolytic decomposition of hydrogen sulfide with cadmium sulfide catalyst. 

The decomposition of sulfuric acid at 850 900 °C [reaction (4.31)], a component of all the sulfur cycles, places severe specifications on the materials of plant construction due to the extremely corrosive nature of the species at high temperatures. This is one of the major issues that is being addressed by the European HYdrogen THErmochemical Cycles (HYTHEC) programme. The... 

The thermochemical decomposition of organic-chlorine and organic-phosphor CW in oxygen environment (these account for the absolute majority of the Baltic dumped chemical weapons) permits them to be reduced to some easy-to-decontaminate or harmless compounds like carbon dioxide, phosphorus oxides or hydrogen chloride, sulphur oxides. The processes take place in combustion chambers at 3,000-3,500°C and a pressure of several MPa, using methods traditional for liquid-propellant rocket engines. The end combustion products of other CW might be additionally condensed to trap the hazardous compounds. 

Similar to thermochemical water splitting cycles, hydrogen sulfide decomposition can also be achieved via thermochemical cycles. Some metal- or metal oxide-based cycles are listed as follows ... 

Electrolysis, and thermochemical and photochemical decomposition of water followed by purification through diffusion methods are expensive processes to produce hydrogen. 

Westinghouse A proposed thermochemical process for decomposing water to oxygen and hydrogen by electrolysis, coupled with the high-temperature decomposition of sulfuric acid ... 

For example, you can combine thermochemical equations (1) and (2) below to find the enthalpy change for the decomposition of hydrogen peroxide, equation (3). 

Huang, C., Raissi, T.-A. 2005. Analysis of sulfur-iodine thermochemical cycle for solar hydrogen production. Part I decomposition of sulfuric acid. Solar Energy 78 632-646. 

A question of interest is the fate of the surplus energy, namely, the difference between that absorbed 137,000 calories (X 2080) and 68,000 calories, the heat of decomposition of HI from thermochemical data, or 69,000 calories. The first electron level for the hydrogen atom is 10.2 volts or... 

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