Naa Zeolite Membrane Prepared On Macroporous Carriers

The efficient pore size of NaA zeolite membranes is between 0.3nm and 0.5nm, which has three-dimensional open-framework and high hydrophilicity. The application perspectives of NaA zeolite membrane are very great in separation of small molecules and low hydrocarbon gases and dehydration of organic solution. However, it restricts its application in the industry that high quality NaA zeolite membrane can not be prepared on the macropore supports. Aiming at this problem, the preparation rules of NaA zeolite membrane synthesized by hydrothermal synthesis and microwave synthesis were investigated in this thesis. Integrating hydrothermal synthesis with microwave synthesis, the new method, microwave-adjusting method, was brought forward, and the high quality NaA zeolite membranes were prepared by this method.The best experimental conditions were found through orthogonal experiments which studied the factors affecting the preparation of NaA zeolite membrane. Moreover, some factors which can affect the enlarging preparation of NaA zeolite membranes were investigated. The methods of introducing seeds were analyzed fully and the new method to introduce seeds, the hot dip-coating, was brought forward. NaA zeolite membranes were characterized by SEM and pure gas permeation measurement, which showed that it improved clearly the quality of NaA zeolite membrane prepared on the macropore supports to introduce seeds on supports using hot dip-coating. Integrating the results of orthogonal experiment with the factors effecting enlarging membrane, the best experimental condition of enlarging preparation of membrane was found. Adopting this experimental condition, NaA zeolite membrane was prepared on macropore tubular support which is 250mm long and its pore size is 3~5u.m and outer-diameter is 12mm. Characterized by XRD SEM and pure gas permeation measurement, NaA zeolite membrane was proven it is dense, continuous, integral, high permeation and has certain molecular sieving property. The permeation of the hydrogen of the membrane is 9.3x10-7 mol m-2 s-1 Pa-1 and the ideal selectivity of H2/N2 H2?C3H8 were 5.1 and 10.3 respectively, which are both over the value of knusen, 3.74 and 4.76. The NaA zeolite membrane was applied to the removal of water from ethanol/water mixtures by pervaporation, and the effects of temperature and difference pressure on the property of membrane were investigated. The total flux of permeance is 1.16kg/m2h-1 and the selectivity is 1054 under the best operating condition.The preparation rules of NaA zeolite under microwave heating were investigated by orthogonal experiments. Further adjusted, the best experimental conditions was found, which was applied to prepare NaA zeolite membrane. The membrane had certain molecular sieving property (an2/h2=6.5). Furthermore, the effects of different stages, method of treatingsupports and baking temperature were studied.Analyzing and Integrating hydrothermal synthesis with microwave synthesis, the new method, microwave adjusting method, was brought forward, and the high quality NaA zeolite membranes were prepared by this method on the macropore supports. Characterized by XRD, SEM, pure gas permeation measurement, NaA zeolite membrane was proven it is dense, continuous, integral and no defect. The permeation of the hydrogen of the membrane is 3.22x10-6 mol m-2 s-1 Pa-1, and the ideal selectivity of H2/N2 was 8.2 , which were both over the values of membrane synthesized by hydrothermal synthesis(aH2/N2=5.1, The permeation of the hydrogen was 9.3x10-7 mol/m2Pas) or by microwave synthesis(aH2/N2=6.5, The permeation of the hydrogen was 1.5x10-7 mol/m2 Pa s). Repeating the experiment, it showed microwave-adjusting method had good repeatability.The formation mechanisms of membrane prepared by hydrothermal synthesis, microwave synthesis and microwave adjusting method were explored in this thesis which can benefit to prepare NaA zeolite membrane on the macropore supports for the future.