Hydrothermal Synthetic Conditions And Phase Ransformation Mechanism Of Zeolite13X

Zeolite13X has been widely used in petroleum chemical, environmental protection, building materials and farming and some other areas due to its good ion exchange performances, catalytic, adsorption. The synthesis method of zeolite13X are many, but the Hydrothermal synthesis is still the main method of industrialization to synthesis zeolite13X. Although the basic theory and technology of Hydrothermal synthesis have been great development, but the forming process and phase-transformation mechanism of zeolite13X with pure and low n(Si/Al) in skeleton by hydrothermal synthsis is not mature. The purpose of the article is to study the problem mentioned above.1.The experiments discusses influence of n(SiO2/Al2O3) n(Na2O/SiO2)、n(H2O/Na2O)and other treaction ratios and reaction temperature, reaction time on hydrothermal synthetic of zeolite13X. The experimental results show that better synthesis conditions as follows: n(SiO2/Al203)=3.2、n(Na20/Si02)=2.3、n(H20/Na20)=60、reaction temperature T=90℃、reaction time t=6h. Zeolite13X with pure and low n(Si/Al)(1.25) in skeleton can be synthesised in this condition.2. The phase transformation mechanis of synthesis process of zeolite13X is discussed through the analysis of produc in diffrernt reaction time by the characterization of XRD, SEM, FT-IR, Raman and combined with crystallization process of zeolite A and sodalite.(1) The XRD and SEM show that the silicon aluminium acid anion frame in zeolite13X has been formed in the reaction time of1.5h. Along with the continuous reaction, Al of the system gradually added silicon aluminium anion skeleton to replace Si, the n(Si/Al) in skeleton decreases gradually. The n(Si/Al) in skeleton is the lowest (1.25) in reaction time for6h, but, it begins to increase gradually when the reaction time exceed6h which also change the crystals structure of Zeolite.(2) The FT-IR and Raman show that the vibration frequency of zeolite skeleton also produce displacement with the n(Si/Al) in skeleton changed. When the n(Si/Al) in skeleton decreased, the vibration frequency move to low wave digital.In view of the Al-Obond have low vibration frequency than Si-0bond, when Al of the system gradually added silicon aluminium anion skeleton to replace Si, the vibration frequency of zeolite skeleton move to low wave numbers.3.The result shows that phase transformation process in the hydrothermal synthetic of zeolite13X is changing. Different with crystallization mechanism of zeolite A and sodalite, crystallization mechanism of zeolite13X is the phase transformation mechanism When the n(Si/Al) in skeleton gradually decreases, the phase transition process: zeolite13X(Ⅰ)(Na1.84[(Al2Si4)O11.92]·7H2O, space group F)�'zeolite13X (Ⅱ)(Na2[Al2Si3.3O10.6]·7H2O,space group Fd-3m[227])and zeolite13X (Ⅲ)(Na2.06Al2Si3.8O11.63·8H2O,space group F�'zeolite13X (Ⅳ)(Na2Al2Si2.5O9·6.2H2O,space group F). When the n(Si/Al) in skeleton gradually increases,the reverse phase transition process: zeolite13X(Ⅳ)(Na2Al2Si2.5O9·6.2H2O, space group F)�'zeolite13X(Ⅱ)(Na2[Al2Si3.3O10.6]·7H2O, space group Fd-3m[227]) and zeolite13X(Ⅲ)(Na2.06Al2Si3.8O11.63·8H2O, space group F)�'zeolite13X(Ⅰ)(Na1.84[(Al2Si4)O11.92]·7H2O, space group F) and zeolite13X(Ⅲ)(Na2.06Al2Si3.8O11.63·8H2O,space group F).