In situ reaction synthesis of needle-like macroporous mullite supports

The needle-like structured porous mullite ceramic membrane supports were prepared using kaolin, Al₂O₃ and Al(OH)₃ as raw materials by in-situ reaction sintering. Al₂O₃/kaolin and Al(OH)₃/kaolin mixtures with different contents of AlF₃ additives were selected, respectively. The effects of different aluminium resources and doping amount of the additives on the needle like structured macroporous mullite support formation were investigated. Results show that topaz is formed prior to the formation of needle-like mullite and the needle-like mullite formation is closely related to the topaz content in samples. Formation mechanism of needle-like mullite is vapor-solid reaction mechanism. The needle-like structured porous mullite support with porosity of more than 35% and average pore size of 1.5 μm is more easily prepared using the Al(OH)₃/kaolin mixture as raw materials, and it's quantity increases with the AlF₃ content increasing.