Cost-effective macro-porous mullite-corundum ceramic membrane supports derived from the industrial grade powder

In order to develop cost-effective macro-porous ceramic membrane supports, the porous supports with large pore size were prepared from the coarse industrial mullite-corundum powder (M) with the mixture of kaolin and basic carbonate magnesium (KM) as sintering additive. Crystalline phase transition mechanism of the sintering additive and the supports was studied respectively by TG/DTA and XRD. The results confirm that at 1200–1400 °C α-cordierite formed from the sintering additive, and that above 1400 °C α-cordierite decomposed into mullite and liquid glassy phase. Sintering characteristic of the coarse mullite-corundum compacts was revealed as a function of KM/M mass ratio. The result indicates that the sintering ability of coarse mullite-corundum improved because of the produced liquid silica-rich glassy phase via the decomposition of KM-derived α-cordierite. In addition, the open porosity of the macro-porous mullite-corundum could be effectively tailored by choosing the KM/M mass ratio, the pore-former/M mass ratio and sintering temperature. The fabricated mullite-based macro-porous supports showed an average pore size of 26.21 μm and nitrogen flux of 2.375 × 104 m3/(m2 h), as well as good mechanical and thermal properties.