Existing and Promising Technologies for Hydrogen Sulfide Decomposition into Hydrogen and Sulfur

Hydrogen sulfide is a very attractive raw material for the production of hydrogen. The dissociation energy of H 2 S (21 kJ/mol at room temperature) is much lower than that of water (286 kJ/mol) or even hydrocarbons (76 kJ/mol for methane); moreover, the hydrogen bond energy in the H 2 S molecule is the lowest among all natural hydrogen compounds. However, hydrogen sulfide has not yet found widespread industrial use as a raw material for hydrogen production. The main obstacle to the creation of an effective technology for this purpose is the very strict thermodynamic limitations of the reaction of hydrogen sulfide decomposition into elements H 2 S Û S + Н 2 – Q. This review is devoted to the analysis of the known approaches to the production of hydrogen and sulfur from hydrogen sulfide, their shortcomings that cause the failure of the previously proposed technologies, as well as the ways of possible creation of effective processes for this purpose. The review focuses on non-stationary cyclic processes, which can be considered one of the most promising ways to create an effective H 2 S decomposition technology.