Study On Preparation And Properties Of Zeolite Via Fly Ash

It has many years history that using fly ash as the raw materials to synthesize zeolite. Especially in recent years, fly ash production increased significantly with the development of industry and the widespread use of power. If the solid industrial waste can not be used by the reasonable ways, they will cause serious harm to environment. So the comprehensive utilization of fly ash has been a potential research topic for many researchers. Total mass percent of SiO2and Al2O3in fly ash is more than70%, and they are the main components of zeolite molecular sieve. Therefore, more and more people take the fly ash as raw materials to synthesize a variety of zeolite molecular sieves of high purity. Fly ash composition is inevitably much different in different place, synthetic methods are different too. A lot of simple and efficient methods are proposed and applied by researchers with the development of synthetic process.This study takes the fly ash from Northeastern China as raw material of synthetic zeolite. The fly ash has high contents of calcium and iron, and the components are respectively4.41%of CaO and10.48%of Fe2O3. The experimental removal of calcium, iron and other metal impurities by physical-chemical method is investigated. Fly ash ground to0.05mm for magnetic selection, then mix the fly ash with hydrochloric acid to remove impurity further. Experiments show that best reaction conditions are as follows: the mole ratio of fly ash and3mol·L-1hydrochloric acid is1:3, reacting temperature is65℃, and the time is5h. Finally Si/Al ratio is2.91, and Fe2O3content is2.07%, and CaO content is2.03%in the processed samples.The fly ash after removing impurity is used as raw material of zeolite.13X zeolite is synthesized by alkali melting-hydrothermal method. Zeolite product is analysed by XRD、SEM、FT-IR and TG methods. Results show that adding crystallization directing agent and template agent into the reaction system is necessary in order to synthesize13X zeolite of high purity. The reactants are calcined for2h at600℃and the grey base ratio of1:1.7. Distilled water is mixed into clinker, and then the aging stage begins.20%of crystallization directing agent and1.5%of template agent into aging system are feasible. The system is transferred into a high-pressure reaction vessel after aging6h, and then zeolite crystallizes for20h in the oven under100℃.13X zeolite was obtained after filtration and dryness.Adsorption is the main purpose of zeolite, and adsorption quantity reflects the quality of zeolite product.13X zeolite product was tested by water-adsorbing and CO2-adsorbing experiments. The water-adsorbing quantity is35.93%and CO2-adsorbing quantity is14.08%after high temperature and vacuum activation.