Assessment of nanoporous structure in novel H2–selective silica–based membranes via integrated gas transport modeling: Membrane development and characterization

As the world moves toward a low–carbon future, hydrogen (H2) is playing a key role in sustainable energy strategies, driving research into the development of efficient and scalable H₂ separation systems. In this study, a low–temperature chemical vapor deposition method was employed to deposit a H2–selective silica layer onto a titania membrane, using tetraethoxysilane (TEOS) as the silica source and oxygen at 250oC. The membrane modification was performed in stages, with ozone post–treatments applied to promote the formation of a stable, purely inorganic structure by decomposing residual organics and activating the surface for subsequent deposition. The resulting SiO2/TiO2 membrane demonstrated a favorable balance between permeance and selectivity, achieving a H2 permeance of 1.9×10–7mol m–2s–1Pa–1 and a H2/CO2 permselectivity of 80.4 at 250oC. Additionally, a theoretical mass transport model was applied at each modification stage to monitor pore structure evolution, identify dominant transport mechanisms, and advance the understanding of structure–permeation relationship.