煤系高岭土酸浸脱铝水热合成NaY分子筛

以煤系高岭土为原料,经煅烧、酸浸脱铝工艺,首次在酸浸偏高岭土-碱水热反应体系中合成了NaY分子筛.采用XRD,SEM对所合成样品进行表征,考察了体系中碱度、硅铝比、老化过程、晶化过程对NaY分子筛合成的影响.结果表明:该水热反应体系适宜的碱度条件为n(H2O)/n(Na2O)=80,碱度过高或过低均会出现P型分子筛杂相.适宜的硅铝配比为n(SiO2)/n(Al2O3)=6.4;老化有助于生成纯相、结晶度好的NaY分子筛,其适宜的老化温度为50℃、老化时间为4h.晶化温度过高或晶化时间过长易转晶生成P型杂相,适宜的晶化条件是晶化温度为85℃、晶化时间为24h.在该反应体系中反应原料由偏高岭土酸浸脱铝后获得,产物结晶度较高,无杂晶,晶形完整,粒度为2μm左右.

Hydrothermal synthesis of NaY molecular sieve from coal-series kaolin by acid-leaching dealuminization

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 after 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(Al2O3),aging process and crystallizing process on NaY molecular sieve synthesizing were investigated.The results show that the proper alkalinity condition is molar ratios n(H2O)/n(Na2O)=80.The higher or lower alkalinity will cause molecular sieve impurity phase.The optimum n(SiO2)/n(Al2O3) is 6.4.The aging 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 crystallizing temperature and time are 85 ℃ and 24 h,respectively.The reaction material is easily yielded by acid-leaching only once and the 2 μm synthesized NaY zeolites are of a higher crystallinity and excluding impure crystals.