Hydrothermal synthesis of NaY molecular sieve from coal-series kaolin by acid-leaching dealuminization
Abstract：Taking coal-series kaolin as the material, the high-silica NaY molecular sieve was synthesized firstly in the hydrothermal reaction system of acid-leaching metakaolinite-alkali af- ter calcination and acid-leaching processes. The product was charactered by XRD and SEM. The effects of various hydrothermal conditions, including the molar ratios of n(SiO2)/ n(A12O3), aging process and crystallizing process on NaY molecular sieve synthesizing were in- vestigated. The results show that the proper alkalinity condition is molar ratios n(H20)/ n(Na2O)=80. The higher or lower alkalinity will cause molecular sieve impurity phase. The optimum n(SiO2)/n(A12O3) is 6.4. Theaging process contributes to generate pure and good crystallinity NaY molecular sieve, and the proper aging temperature and time are 50 ℃ and 4 h, respectively. The higher crystallizing temperature or longer crystallizing time will easily cause crystal transformation and yield P molecular sieve impurity phase. The proper crystalli- zing temperature and time are 85 ℃ and 24 h, respectively. The reaction material is easily yiel- ded by acid-leaching only once and the 2/μm synthesized NaY zeolites are of a higher crystallini- ty and excluding impure crystals.
Keywords：acid-leachingcoal series kaolinhydrothermal synthesisNaY molecular sieve
Publication Date：2012-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 811-816 )