Novel preparation of low-cost support for NaA zeolite membrane by utilizing natural clay

The membrane support is the basis for the preparation and application of the zeolite membrane and its cost and properties directly determine the performance of the zeolite membrane as well as its industrial applications. In this paper, the direct synthesis of NaA zeolite membrane on a novel low-cost support via an in situ reaction by utilizing natural clay can enable a significant reduction in manufacturing costs. During the preparation of the support for the NaA zeolite membrane, additives, such as Al2O3, Al(OH)(3) and AlF3, were combined with kaolin clay and used as alumina precursors. Using the resulting porous mullite support, the effects of the firing temperature on the permeability and pore structure of the support were investigated extensively. The results of the experiment showed that silica in the natural clay was reacted by the Al2O3 precursor additives, producing a needle-like mullite in situ that served as a rigid skeleton porous structure for the support. Thus, a network porous structure of the mullite support could be formed during sintering process. The prepared network porous structure mullite supports exhibited a high pure water permeance of 3324 L m(2) h(1) bar(1), open porosity of 41.8% and a mean pore size of 1.36 mu m which was ideal for the preparation of the NaA zeolite membrane.