High-performance macro-porous alumina-mullite ceramic membrane supports fabricated by employing coarse alumina and colloidal silica

Cost-effective porous alumina-mullite ceramic membrane supports were prepared from mixtures of different alumina/silica (Al2O3/SiO2) ratios of coarse α-alumina micro-powder and colloidal silica (CS). The effects of sintering temperature, Al2O3/SiO2 ratio and cornstarch content on the crystalline phase evolution, microstructures, porosity, bending strength, pore size distribution and permeance of the ceramic membrane supports were systematically investigated. The results showed that the increase in sintering temperature was beneficial to the mullite formation and the bending strength. However, it was adverse to the improvement of porosity and the pore size distribution which have positive correlation with the permeance of the supports. The increases in Al2O3/SiO2 ratio and cornstarch were favourable to the mullite formation, improvement of porosity, pore size distribution and morphology of the supports, but were unfavourable to the bending strength. A high-performance porous alumina-mullite ceramic support with suitable porosity (50.5%) and pore size (3.1 μm), sufficient mechanical strength (49.7 MPa) and high permeances was successfully synthesized by optimizing the sintering temperature, Al2O3/SiO2 ratio and cornstarch content. Moreover, the proposed simple method shows much potential for the preparation of high-performance porous alumina-mullite ceramic membrane supports.