Synthesis and perfection evaluation of NaA zeolite membrane

Synthesis of zeolite NaA membranes with high permeance under microwave radiation on mesoporous-layer-modified macroporous substrates for gas separation

“…The permeance of the gases decreased with the increase of permeate molecular kinetic diameter, which showed the molecular sieving effect of the zeolite NaA membrane. This is similar to that the relationship between the sizes of the defects, zeolite pore diameter and permeate gas, and the mechanism mainly controlling the gas permeation properties of the zeolite membrane by the molecular sieving of the NaA membrane as discussed previously [28]. …”

“…For series I and II, the synthesis mixture was prepared by mixing sodium aluminate, water glass, sodium hydroxide, and water under vigorous stirring for 24 h to form a homogeneous gel with molar ratio of 3Na 2 The synthesis process was carried out in a modified domestic microwave oven operating at 2450 MHz [27,28]. The substrate was placed vertically with a Teflon holder in a polyethylene bottle.…”

“…The membrane was sealed in a permeation module with the zeolite membrane on the high-pressure side [27,28]. The gas permeance properties and the integrity of the membranes were measured by a soap-film flowmeter under a pressure difference of 0.10 MPa at 25 • C. The permselectivity of A/B, α A/B , was defined as the permeance ratio of gas A to gas B.…”

Synthesis and properties of A-type zeolite membranes by secondary growth method with vacuum seeding

“…The solution for synthesizing A-type zeolite membrane was prepared according to the procedure reported previously [15,24]. The aluminate solution was prepared by dissolving 156 g sodium hydroxide in 300 ml deionized water, then adding 2.1 g aluminum foil to the solution at room temperature.…”

“…It is well known that the presence of seeds on support surface plays an important role in membrane formation. Synthesis with seeds gives a better control of the membrane formation process by separating the crystal nucleation and growth with a shortened crystallization time [14][15][16]. In ad-dition, the secondary growth method ensures growth of the zeolite crystals on the support rather than in the solution and restrains the nucleation transform to other crystals [17,18].…”