Novel interface enhancement strategy enables SiC fiber membrane for high-temperature gas/solid filtration

The high gas permeance of ceramic membranes is the most important indicator of hot-gas filtration. Ceramic membranes made of fibers show significant potential for filtering dust-laden gases owing to their high porosity and high gas permeance. A novel method is proposed for preparing a SiC fiber separation layer on a rigid ceramic support that endows the membrane with a high porosity. However, the interfacial adhesion between the support and separation layers was low as there were insufficient connection points. Therefore, a solvothermal method was proposed for the in-situ vertical growth of TiO2 nanocords on the surface of a SiC support (SiC–TiO2). Next, a SiC fiber separation layer was deposited on the SiC–TiO2 support to improve the interfacial adherence. The fabrication parameters of the SiC fiber layer, such as the solid content of the coating slurry and sintering procedure of the separating layer, were investigated in detail. At a SiC fiber content of 6 wt%, spray-coating times of 2, and sintering temperature of 1150 °C, a complete fiber layer was successfully deposited on the rigid ceramic support. The resulting membrane had a thickness of 100 μm, porosity of 91%, average pore diameter of 6.8 μm, and gas permeance of 440 m3·m−2·h−1·kPa−1. In the filtration of dust-laden gas containing SiO2 as simulated dust (average particle size, 0.3 μm), the rejection rate was >99.9%; further, after four cycles of filtration–backwashing, the pressure drop was <0.82 kPa. The outlet dust content was less than 0.1 mg m−3. Moreover, this membrane exhibited superior filtration ability at 500 °C. The findings of this study can aid the fabrication of ceramic fiber membranes with a high gas permeance and high interfacial adherence for industrial applications.