Synthesis And Characterization Of Zeolite A By Microemulsion Method

ant class of materials in the field of materialsscience. Their unique pore architectures have made them popular in a widerange of applications in catalysis, adsorption, separation and host-guestassemblies. When the crystal size of the zeolite is less than 0.1 μm, it is calledthe nanosized zeolite. As nanosized particles, it has been paid more attentionfor its unique catalytic properties. Compared with the conventionallymicrosized zeolite, nanosized zeolite has more external surface, highersurface energy, shorter channels, enriched surface hydroxyl groups,ion-exchange sites and the array of micropore-opening. Therefore, it hasmany advantages in the catalytic reactions such as high activity, specialselectivity to products, strong resistance to the coke and activation of bulkmolecules and nanosized zeolite is also can be used for the preparation ofsupported zeolite films and membranes. Frthermore, the study on synthesisof nanosized zeolite can also increase our knowledge of the nucleation andthe research of synthesis ofnanozeolites has drawn more and more attention. So far, two methods areoften used for preparation of Nanocrystals: synthesis from clear solutions andZeolites constitute an importcrystal growth procedure. Therefore,gels;confined-space synthesis.As a chemical-based materials synthesis technique, the reversemicroemulsion methods preparing nanosized particles have been developedin recent dec nanosizewater droplets show t by the means of thesurfactants( sometimes and cosu lms, that serve as nanosize testtubes, thus l gation. Anddue to the compartmentalized droplets, the monodispersed nanoparticles sizecan be easily controlled in such media. e, grow andaggrades. In the microemulsions-mediated methods, thehermodynamically stabilizationrfactants)fiimiting particles growth and minimizing particle aggreParticles can nucleategate in the water pool under the confinement of the water-oil interface,so that flexibility of the interface, the size of the water pool and also the ratio ofreactants can affect the characteristics of the resultant particles. In the varietymethods of the nano-sized material preparation, microemulsion was adoptedbecause of the simple equipment, easily controlled process and the mildreaction conditionIn this dissertation, we developed a new method, hydrothermalmicroemulsion, to synthesized zeolite A. The microstructure,particle sizeandmorphologies of product were characterized by means of X-ray difraction(XRD),scanning electron microscopy (SEM), which help us studying theeffect of different microemulsion composition on the product.The zeolite A particles were prepared in quaternary system containingCTAB/n-butanol/n-heptane/LTA synthesis gel. Compared with the particlesynthesized hy conventional hydrothermal method, the products are smallerand possess well size distributions. And we find that. When the massfraction of CTAB/n-butanol increased, the crystallization degree of the productincreased first but decreased after a certain value. When the mass fraction ofCTAB/n-butanol was between 0.20～0.24, the spherical product with the sizerangparticles were prepared in quaternary system containingh the other twosolving from 100～200nm and well size distributions could be obtained.Otherwise, zeolite A could not be obtained or obtained product with bad sizedistributions and heavily agglomeration. Much reaction time lead to lowercrystallization degree.The zeolite A particles were prepared in quaternary system containingCTAB/iso-octane/n-heptane/LTA synthesis gel. When the mass fraction ofCTAB/n-butanol increased, the crystallization degree of the product alsochanged: increasing first while decreasing last. But the range of massfraction with which fine product could be obtained moved to the region ofmore CTAB/n-butanol. The value is about 0.24～0.26. The spherical productwith the size ranging from 100～200nm and well size distributions could beobtained. As the microemulsin with n-heptane, much reaction time lead tolower crystallization degree.The zeolite ACTAB/cyclohexane/n-heptane/LTA synthesis gel. But the microemulsionregion decreased. The range of mass fraction with which fine product couldbe obtained moved to the region of less CTAB/n-butanol. The value is about0.18～0.20. The spherical product with the size ranging from 100～250nmand well size distributions could be obtained. And the same witents, much reaction time lead to lower crystallization degree.Compared the microemulsion system with three different solvents, wefind that there is a special CTAB/n-butnol mass fraction range in all the threesystems. But the range changed with the solvent. We arrange the threedifferent by increasing the mass fraction of CTAB/n-butanol:cyclohexane