Metal Oxide 3D Porous Structures for High-Temperature Thermochemical Applications

Abstract

Thermochemical cycles utilizing oxides of multi-valent metals present a promising pathway for sustainable energy conversion and storage, leveraging reversible reduction-oxidation (redox) chemical reactions driven by heat to produce fuels, separate gases, or store energy. This presentation introduces the fundamentals of such redox metal oxides-based thermochemical cycles and their diverse applications, including hydrogen production, CO₂ splitting, air separation, and thermochemical heat storage. Central to optimizing these processes are reactor systems that facilitate efficient heat and mass transfer, where the design and materials of the reactive redox structures play a crucial role. Three-dimensional 3D porous structures combine high surface area, mechanical robustness, and controlled porosity to enhance reaction kinetics and thermal management. We focus on recent advances in the fabrication of 3D porous metal oxide architectures specifically tailored for thermochemical reactors, and exemplarily explore the process of material selection of suitable metal oxides for a thermal storage unit currently under development by DLR and its partners. Manufacturing techniques such as additive manufacturing, templating, and sintering are discussed with emphasis on scalability and reproducibility. An outlook is given on the challenges and opportunities for scaling up these materials and integrating them into practical thermochemical reactor systems, aiming to bridge the gap between laboratory research and industrial deployment.