Fabricating hydrothermally robust ceramic membranes from amorphous yttrium-doped SiO2-ZrO2 composites

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SiO2-ZrO2 ceramic composites are necessary for highly demanding separation processes. We demonstrated the efficacy of using yttrium doping to improve the hydrothermal stability of SiO2-ZrO2 composite-derived membranes. In long-term hydrothermal stability tests involving steam-N2 mixture permeation between 500–800 °C, N2 permeance for an undoped SiO2-ZrO2 membrane fabricated on an α-Al2O3 substrate decreased from 5.0 × 10−6 to 2.5 × 10−6 mol m−2 s−1 Pa−1 after 60 h between 500–700 °C and to 3.2 × 10−8 mol m−2 s−1 Pa−1 after 32 h at 800 °C. The yttrium-doped SiO2-ZrO2 membrane achieved a stable N2 permeance of 6.5 × 10−6 mol m−2 s−1 Pa−1 after 60 h between 500–700 °C, which decreased to 8.0 × 10−7 mol m−2 s−1 Pa−1 after 32 h at 800 °C. Microstructural analyses revealed that integrating yttrium into a SiO2-ZrO2 matrix suppressed segregation and aggregation rates of ZrO2 nanocrystals to form more stable microstructures.