| Zeolites A, X and composite zeolite A/X were synthesized by ultrasonic irradiation method and space-confined method with methylcellose as a space-confined additive, respectively. As for the space-confined method, different molar ratio of the source materials and confined effect of the different content of methylcellose as space-confined additive were studied; As for the ultrasonic irradiation method, the effects of different molar ratio of the source materials, crystal time, crystal temperature and ageing time on the synthesized zeolites were evaluated. The samples were characterized by XRD, BET, TEM, FT-IR and TG-DSC characterizations. The results show that in the system of 5.85Na2O:Al2O3:2.7SiO2:155H2O, compared with the sample synthesized by conventional hydrothermal method, zeolite A synthesized by space-confined method not only has higher crystallinity, smaller interplanar distance, smaller and more uniform particle(about 250nm), richer microporous structure, more perfect crystal structure, stronger relative absorbance, but also has the same thermal stability. The space confinement additive methylcellulose successfully limited the growth of particles, and the sample synthesized by 15g gel added 2.5g methylcellulose has higher crystallinity(110%), larger external surface area(24.3m /g), better crystal structure, more uniform particle size(1.5μm), the average particle size decrease 3 times in the system of 5.80Na2O:Al2O3:2.98SiO2:4.28KOH:119H2O. When the added-methylcellulose increases, the surface area and microporous volume of zeolite X decreases greatly, the particle size decreases slightly, but external surface area increases first and then reduces. In the system of 6.07Na2O:Al2O3:4.23SiO2:103.8H2O, the results show that the sample synthesized by conventional hydrothermal method is mixed crystal, but zeolite X was synthesized by MC aqueous solution as a space confinement additive, which has large external surface area(56.6 m2/g), small average particle size, uniform crystal structure, but microporous area reduces.As for ultrasonic irradiation method, the results show that relatively high molar ration of SiO2 and Al2O3 favor for the forming of zeolite X, however, it is unfavorable for the synthesis system of zeolite A. The formation of zeolite X needs higher crystal temperature, longer ultrasonic crystal time in the system of 5.85Na2O:xSiO2:Al2O3:105H2O (x=2.3,2.7,3.0,3.3). When the ratio of SiO2/Al2O3 is 2.3, the crystallinity and the average particle size increase, but the interplanar distance and the external surface area reduce as the ultrasonic time increasing. Zeolite A has the same tendency as the crystal temperature increasing. In this system, spherical nanosize zeolite A was fast synthesized without heating, compared with sample synthesized by conventional hydrothermal method, the sample synthesized by ultrasonic 40min has small and uniform particle size(about 30nm), large external surface area(47.2 m2/g), but the sample synthesized by ultrasonic 60min has large and uniform particle size(about 200nm), small external surface area(21.4 m2/g), perfect and cuboidal crystal structure, and they have the same thermal stability. The external surface area increases first and then reduces as ultrasonic time increasing in this system. When the ratio of SiO2/Al2O3 is 2.7, nanosize composite zeolite A/X was synthesized under ultrasonic 20min at 60℃, its external surface area and microporous area are 121.14 m2 /g and 257.70 m2 /g, respectively, its particle is spherical and uniform, its particle size is about 10nm, its microporous structure is ordered and its skeleton structure is perfect. The mass ratio of zeolite A reduces, but the mass ratio of zeolite X increases, BET and external surface area increase first and then reduce, while microporous area slightly reduces as ultrasonic time increasing. When the ratio of SiO2/Al2O3 is 3.0, the composite zeolite A/X was also synthesized by ultrasonic irradiation method at 60℃, the mass ratio of zeolite A reduces, but the mass ratio of zeolite X, BET, external surface area and microporous area increase; zeolite X was synthesized by ultrasonic irradiation method after ageing 12h, the crystallinity and yield increase, but BET and external surface area reduce first and then increase as ultrasonic time increasing. The crystallinity, yield, BET and external surface area increase, but the particle size reduces as ageing time increasing. Compared with sample synthesized without ageing-treatment, the as-synthesized sample after ageing has higher crystallinity and yield, larger BET and external surface area, smaller particle size and more ordered microporous structure. When the ratio of SiO2/Al2O3 is 3.3, the results show that the crystal grain is smaller, the external surface area is larger, and the crystal structure is more ordered as ultrasonic time increasing at 60℃without ageing-treatment; As ageing time increases, the crystal grain gets smaller, the external surface area becomes larger and the crystal structure is more ordered under the same ultra sonic time; Zeolite X synthesized under ultrasonic 60min, its BET and external surface area are 472.4 m2/g and 185.5 m2/g, respectively, its particle size is about 10nm, and its microporous structure is ordered.In comparison with conventional hydrothermal method and space-confined method, the synthesis of zeolite by ultrasonic irradiation method is the most simple, the operation is most convenient with crystal temperature reduced and crystal time shortened. The as-synthesized zeolite by ultrasonic irradiation method has higher crystallinity, larger surface area and external surface area, stronger relative absorbance, smaller and more uniform particle size, and more ordered microporous structure.
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