Production strategies for complex shapes cer-cer structures by microextrusion

Ceramic membranes operating at high-temperature are a key-technology for hydrogen separation processes including advanced chemical reactors, power generation with pre-combustion, CO2 capture, hydrogen separation/ purification from gas mixtures as in water-gas shift implants and methane reforming. Cer-cer composites based on BaCe0.65Zr0.20Y0.15O3-?-Gd0.2Ce0.8O2 (BCZY-GDC) have gained increasing attention as asymmetric membranes for H2 purification, for their high proton-electron conductivity, 100% selectivity, temperature and chemical stability, and intrinsic lower cost in respect to the Pd-based technology. However, hydrogen permeation fluxes reached until now are still too low for industrial application. The microstructure of the porous support plays a crucial role to increase the gas access and transport through the porous support. In this work, complex shaped BCZY-GDC composite supports were successfully fabricated for the first time by microextrusion. Honeycomb-type geometries with different cavity sizes were designed in order to increase the fluid dynamic properties of the support without affecting its mechanical stability. Different high solid loading water based pastes with suitable rheological properties were formulated and microextruded in multilayer structures without nozzle clogging. Different drying processes methods were deeply investigated to obtain cracks-free extruded green bodies. The process optimization allows the production of BCZY-GDC supports with engineered porosity in terms of size, quantity and directionality of the pores.