原位反应烧结合成针状结构多孔莫来石载体

In situ Reaction Synthesis of Needle-like Macroporous Mullite Supports

采用粘土矿物高岭土、Al_2O_3和Al(OH)_3为原料,原位反应烧结合成了针状结构多孔莫来石陶瓷膜载体.考察了不同铝源的添加对针状结构多孔莫来石载体形成的影响,并对其形成机制进行了研究.研究结果表明:针状结构莫来石形成机制为气固反应,在针状结构莫来石形成前有氟黄玉生成,并且与氟黄玉的生成量密切相关.以Al(OH)_3作为添加铝源的组成中氟黄玉更容易生成,并且随AlF_3含量的增加而增加,在随后烧成过程中转化为具有刚性骨架的针状结构莫来石,从而使多孔载体具有较高的孔隙率(>35%)和相对高的孔径(1.5μm).

The needle-like structured porous mullite ceramic membrane supports were prepared using kaolin, Al2O3 and AI（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 1.5μm is more easily prepared using the Al（OH）3/kaolin mixture as raw materials, and it＇s quantity increases with the AlF3 content increasing.