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Materials and components for Hydrogen production by sulphur based thermochemical cycles

Final Report Summary - HYCYCLES (Materials and components for hydrogen production by sulphur based thermochemical cycles)

The HYCYCLES project identified potential construction and catalyst materials for the targeted key components of solar and nuclear powered sulphur based thermo-chemical cycles and for the catalytic high temperature reduction of sulphur trioxide (SO3) as one of the crucial steps of those processes.

The project's main development route was based on ceramic materials from the silicon carbide (SiC) family, to be used as construction materials for sulphuric acid decomposers of two different configurations, namely a solar receiver reactor and a compact heat exchanger. The base material to be employed as oxygen (O2) separation membrane from the SO3 decomposer reactor outlet mixture was yttria-stabilised zirconia (YSZ). The material of choice for the process components that faced the highest temperatures and most corrosive environments was SiC. Specific oxides were qualified as catalysts for the SO3 decomposition with significantly higher activity and higher stability than the reference materials.

Mock-ups of sub-units and prototypes of the mentioned decomposers were developed and tested. Laboratory test rigs for different purposes such as corrosion tests, catalyst development, catalyst stability tests and selectivity of separation membranes were built and used to qualify materials and to prepare and accompany the prototypes' test operation. For example, one of the largest SiC heat exchanger ever made was realised. The solar receiver-reactor turned out practicable and suitable for scale-up purposes by multiplying the module on top of a solar central receiver system. The experimental data from lab testing and prototype testing were used to refine models of components, process units and of the process as a whole to enable the evaluation of plant and hydrogen production costs and to enable the elaboration of potential scale-up scenarios.

Further information could be provided at the project website, at online. The HYCYCLES coordinator was Dr Martin Roeb from DLR.

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