Low-cost porous mullite ceramic membrane supports fabricated from kyanite by casting and reaction sintering

Porous mullite supports are firstly fabricated by casting and reaction sintering based on kyanite with Al(OH)3 as porogenic agent. The effects of composition and sintering temperature on phase evolution, microstructure, apparent porosity, pore size distribution, linear shrinkage, gas permeation flux and mechanical property of supports are systematically investigated. Results show that the mullitization of kyanite generates needle-like mullite crystals, which form skeleton structures and improve the apparent porosity and strength of supports. Al(OH)3 addition not only promotes the formation of needle-like mullite but also enhances the apparent porosity of supports. Temperature promotes the development of mullite, from 1450 to 1500 °C, the amount and size of needle-like mullite crystals increase, ≥1500 °C, they reveal columnar morphology. The support prepared with kyanite+40 wt%Al(OH)3 sintered at 1500-1550 °C exhibits high apparent porosity, good gas permeation flux, excellent mechanical performance and interlocked network structure composed of well development needle-like mullite.