Active phase deposition and insertion methods in dense ceramic membranes for hydrogen separation and production

Hydrogen is strategically important in the industrial and energy sectors, and its separation at commercial scale represents a significant share of production costs. Dense ceramic membranes offer an alternative separation technique that is highly selective and scalable, making them promising for small-scale hydrogen production, including plants based on biomass valorization. This thesis investigated key factors affecting the performance of dense ceramic membranes, focusing on surface activation and modification of BaCe0.65Zr0.20Y0.15O3-δ–Ce0.8Gd0.2O2-δ (BCZY-GDC) composites. The work focused on platinum cluster deposition, an emerging activation method that has shown promise but requires better understanding and reproducibility. A robust deposition protocol was developed and optimized through systematic screening of solvents and concentrations to maximize deposition efficiency and minimize platinum waste. The method was then applied to membranes and validated through permeation and reaction tests. The membranes achieved remarkable hydrogen permeation fluxes with very small platinum quantities, among the highest reported in the literature. Exsolution, another promising method for introducing active phases, was also investigated by testing the membrane's single-phase constituents individually under different reducing conditions and reactions. Finally, an asymmetric membrane featuring a thin BCZY layer on one side and GDC on the other was used to assess the role of each constituent. These tests provided insight into how the surface phase influences performance and helped identify the limiting step, surface kinetics or bulk diffusion, depending on feed composition and test configuration.