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 (H 2 ) is playing a key role in sustainable energy strategies, driving research into the development of efficient H 2 separation systems. In this study, a scalable low–temperature (250 °C) chemical vapor deposition (CVD) method using tetraethoxysilane (TEOS) and oxygen was employed to deposit a H 2 –selective silica layer on a commercial titania membrane. In contrast to conventional single-stage CVD routes, a novel addition of intermediate ozone (O₃) treatments between deposition steps promoted the formation of a stable, purely inorganic structure by decomposing residual organics and activating the surface for the subsequent deposition. The resulting SiO 2 /TiO 2 membrane demonstrated a favorable balance between permeance and selectivity, achieving a H 2 permeance of 1.9 × 10 – 7 mol m −2 s −1 Pa −1 and a H 2 /CO 2 permselectivity of 80.4 at 250 °C. Additionally, a theoretical mass transport model was applied at each modification stage to assess pore structure evolution, identify the dominant transport mechanisms, and advance the understanding of structure–permeation relationship. • A hydrogen – selective silica layer was deposited on a commercial titania membrane. • The membrane demonstrated a favorable balance between H 2 permeance and selectivity. • Chemical vapor deposition was assisted by ozone post-treatments, performed in stages. • Mass transport model assessed pore-size distributions monitoring structural evolution. • Model validated and predicted transport mechanism contributions for six pure gases.