模板剂法水热合成高硅铝比ZSM-5分子筛

Synthesis of ZSM-5 Zeolite with High Molar Ratio of Silica to Alumina by Hydrothermal Crystallization Method with Template

以工业水玻璃和硫酸铝为主要原料,正丁胺为模板剂,利用水热法合成出了高硅铝比ZSM-5分子筛。考察了晶化时间、晶化温度、投料硅铝比、合成体系pH值以及模板剂用量等因素对晶化产物的影响。采用X射线衍射、傅里叶变换红外光谱、低温氮气吸脱附、核磁共振、扫描电子显微镜等手段对合成样品进行了表征。结果表明:合成ZSM-5分子筛最适宜的条件为:晶化时间36h,晶化温度170℃,投料硅铝比200,合成体系的pH=11.0,模板剂加入量为模硅比0.2。在最适宜条件下合成得到的ZSM-5分子筛产物具有高的相对结晶度,BET比表面积为335m2/g,晶粒尺寸约为5μm×15μm,骨架硅铝比大于100。

ZSM-5 zeolites with high molar ratio of silica to alumina were synthesized by hydrothermal crystallization method from industrial grade water glass and aluminium sulfate with butylamine as the template. The effects on crystallization products were investigated in different preparation factors such as crystallization time, crystallization temperature, silica-alumina ratio, pH value of synthesis system and the amount of template. The as-synthesized samples obtained from optimum conditions were characterized by X-ray diffraction, FT-IR, Nitrogen adsorption-desorption technique, nuclear magnetic resonance and scanning electron microscopy. The results showed that the optimum synthesis conditions are： The optimum synthesis conditions of ZSM-5 zeolites were listed as follows： crystallization time is 36 h, crystallization temperature is 170 ℃, silica-alumina ratio is 200, pH value is 11.0 and the molar ratio of template to silica is 0.2. The ZSM-5 zeolites with grain size about 5 μm ×15 μm have a relative high degree of erystallinity and large specific surface area （335 m2/g）. The framework silica to alumina ratio was more than 100.