A road map to planar asymmetric oxygen transport ceramic membranes: An example case based on Fe-doped SrTiO₃

Scalable fabrication of asymmetric oxygen transport membranes offers great potential for oxygen production, energy conversion and chemical synthesis. This study develops a sequential tape casting process utilizing commercially sourced ceramic powders to fabricate planar asymmetric membranes. By systematically adjusting key parameters – particle size, pore former type, casting blade gaps, and sintering conditions, the process achieves bilayer membranes with enhanced compatibility, mechanical integrity, and oxygen transport efficiency. Controlled ball milling yields appropriate average particle sizes (≥0.6 μm) and specific surface areas (≤5 m²/g), preventing cracking and improving homogeneity of ceramic tapes. Through the use of calibrated blade gaps, a corn starch pore former, and sintering at 1350 °C, a bilayer membrane configuration is obtained with distinct porous and dense layers. Large membranes up to ∼87 mm in diameters are further shielded from crack formation by a cautious heating ramp (0.5 K/min) during debinding between 200 °C and 900 °C. High oxygen permeation rates are demonstrated for the asymmetric membranes because of the optimized bilayer configuration, which includes a support layer with a high porosity, a large surface area, and rapid gas diffusion pathways. Additionally, the negative effects from secondary phase formation are eliminated by reducing the sintering time to four hours. Surface activation coatings further improve performance, particularly at low temperatures (650 °C–750 °C) with La_0.58Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) coating of superior surface exchange kinetics. This work is a significant step towards industrial applications by establishing an exemplified framework for producing and applying high-performance, scalable oxygen transport membranes.