Production of complex BCZY-GDC supports by 3D micro-extrusion

Ceramic membranes operating at high temperatures are a key technology for hydrogen separation processes including advanced chemical reactors, power generation, CO2 capture and hydrogen separation/purification from gas mixtures. Thanks to their 100% selectivity, high proton-electron conductivity, intrinsic lower costs if compared with Pt-based technologies and chemical and temperature stability, ceramic composites based on BaCe0.65Zr0.20Y0.15O3-d - Gd0.2Ce0.8O2-d (BCZY-GDC) have gained increasing attention as asymmetric membranes for H2 purification. Nowadays, however, the hydrogen permeation fluxes obtained employing this technology are still not suitable for industrial applications. Asymmetric architectures are an effective way to improve both gas permeation and mechanical strenght of the membrane, due to the combination between a dense and a porous ceramic layer that are commonly composed of the same materials to avoid thermal expansion mismatch between themes. In order to improve the H2 permeation, a lot of research is currently focused on optimizing the microstructure of the porous support aiming to increase the gas access and transport through it. In this work, complex-shaped BCZY-GDC composite supports were successfully fabricated for the first time by 3D micro-extrusion. Honeycomb-type geometries containing different size cavities were designed and produced to promote the support fluidics without affecting its mechanical stability. Different high solid loading water-based BCZY-GDC pastes were formulated finely tuning their viscosity. The latter was then micro-extruded in multilayer structures without nozzle clogging or other process issues. Aiming to obtain cracks-free green bodies, different drying process methods were considered and deeply investigated. Finally, the process optimization allowed the production of engineered porosity BCZY-GDC supports potentially employable in asymmetric membranes