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 m2 h1 bar1, open porosity of 41.8% and a mean pore size of 1.36 µm which was ideal for the preparation of the NaA zeolite membrane.

Performance of Annealed Composite Cellulose Acetate/NaA Zeolite Membrane in Carbon dioxide/Methane Gas Separation

Ramie (Boehmeria nivea) is one type of plant used to produce high quality cellulose fiber. Its fiber is convertible to cellulose acetate (CA), which is commonly used as membrane’s material. Dense CA membrane is used in gas permeation process and the performance is improvable by mineral blending and annealing. This study aims to determine the characteristics of modified CA membranes and the performance in separation of CO2/CH4 gases. Membrane preparation was carried out by using phase inversion technique, while annealing was carried out at 60oC. Furthermore, NaA zeolite was added with various concentrations, which include 5, 10, 15 and 20%. Gas permeation was carried out at 4 barrer for an hour. The performance of the membrane was measured based on its permeability and selectivity. The results showed that CA membrane with 10% zeolite yielded the best performance with CO2 and CH4 permeability of 140.55 and 22.25 barrer respectively and selectivity of CO2/CH4 6.32.

Synthesis of NaA zeolite membrane by maintaining pressure difference between the two sides of the support

Pressure difference assists more Si/Al active ingredient migration to the surface of the support and thus facilitates the formation of uniform and dense zeolite membranes.