| Na-X zeolite has an octahedral skeleton structure(FAU type),large specific surface area and pore volume,good thermal and hydrothermal stability,so it is widely used in many fields such as petroleum,environment,biology,agriculture and medicine and has great potential.In recent years,in order to improve the synthesis efficiency and reduce the water consumption,many synthesis methods have been developed and got breakthrough,such as ionothermal method,steam-assisted method(SAC,VPT),solvent-free method and solid-phase method.Among them,the solid-phase method is a simple process with energy saving,high efficiency,high product yield,less water consumption,less or no wastewater discharge,green and environmental protection,while it is less researched.Thus exploring synthesizing Na-X using solid-phase method has important industry value and scientific meanings.Fly ash might be raw material of aluminosilicate for Na-X because its composition is similar to Na-X.Due to the abundant coal resource in China,fly ash is byproduced with a large amount which will pollute environment in stacking but its utilization is less.Therefore,the process for synthesizing Na-X by solid phase method using chemical agents is studied in detail,as well as the synthesis of Na-X from fly ash by this process in this paper.(1)Zeolite Na-X with high purity,high crystallinity,good morphology and large specific surface area were successfully synthesized from chemical agents by solid phase conversion.The various experimental conditions including SiO2/Al2O3 ratio,alkali/SiO2 ratio,H2O/SiO2 ratio,seed addition,crystallization temperature and crystallization time on the synthesis were studied.The Na-X samples were characterized by means of XRD,XRF,SEM,BET,FTIR and so on,and the optimal synthesis process conditions were obtained.The solid phase process for Na-X is simple and high-efficiency with the H2O/SiO2 ratio reduced from 100 in hydrothermal method to 8,showing energy-saving and environmental-friendly.(2)According to the optimized conditions,the solid phase conversion was successfully applied in the high-valued utilization of fly ash to zeolite Na-X.The effects of factors on synthesis were also investigated by solid phase conversion and the optimized conditions were obtained.Most importantly,the H2O/SiO2 ratio was reduced greatly. |
