Technological and chemical assessment of various thermochemical cycles: From the UT3 cycle up to the two steps iron oxide cycle

The studies carried out on the UT-3 cycle lead to propose an operating mode that was tested with the Mascot Mockup. Additional investigations, partially presented in the present paper point out that the physicochemical properties of the solid and gaseous reactants will make the running of an industrial process very difficult. For instance, the sintering of the solid, the possible reactivity of the embedding matrix, … induce additional operation and then lower very sensibly the efficiency of the cycle. Furthermore, if the toxicity of the reactants is taken into consideration, the attractivity of this cycle decreases. If other considerations than the efficiency of the cycle are taken into consideration, it is possible to investigate other cycles. The present paper shows the first results of the studies carried out on alternative cycles having either low efficiency but involving inoffensive reactants or high efficiency but without using bromine. In the first case illustrated by the iron oxide cycle, it seems that the low efficiency can be partially offset by using abundant and inexpensive energy source. In the second one illustrated by the cerium chloride cycle, the significant industrial experience regarding the chemical engineering of the chloride could make the industrial development easier.