3D-printed ceramic membranes: Fabrication and hydrogen permeation performance

In this work, the possibility of using 3D printing technology as a tool to boost the widespread use of all-ceramic membranes operating at high temperatures for hydrogen separation and membrane reactors is proposed for the first time. Dense ceramic-ceramic composite membranes based on BaCe0.65Zr0.20Y0.15O3-delta-Gd0.2Ce0.8O2-delta were produced by 3D microextrusion. A suitable water-based ink was formulated and thermally/rheologically characterized. Both printing parameters and post-printing operations were carefully adjusted to obtain crack-free and planar membranes. In particular, the use of polyethylene glycol with the lowest molecular weight as desiccant liquid combined with a warm ethanol washing bath is crucial for the production of defect-free microextruded ceramics. The optimization of the whole ceramic process allows the fabrication of ceramic membranes with a relative density of 98.7 +/- 1.1 % and a flexural strength of 98.4 +/- 18.9 MPa. After activation with Pt nano-particles, the 3D microextruded membranes show H2 permeabilities of 0.21 and 0.32 mL min-1 cm-2 at 750 degrees C using a feed stream with respectively 50 % and 80 % of H2 in He. These hydrogen fluxes are among the highest reported so far for symmetric all-ceramic membranes.