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以粉煤灰为原料,采用碱熔融-超临界水热法合成粉煤灰沸石。考察了碱熔融预处理过程中碱的种类、焙烧温度、碱灰比对粉煤灰活化效果的影响;研究了粉煤灰沸石合成过程中晶化温度、碱液浓度、晶化时间、液固比和硅铝摩尔比等对粉煤灰沸石生成的影响,优化合成条件。结果表明:Na_2CO_3为活化剂,碱灰比为1.2∶1,850℃下焙烧3 h对粉煤灰的活化效果最好;经碱熔融预处理的粉煤灰与水混合在超临界水热条件下可合成钙霞石,且最佳晶化条件为加蒸馏水,液固比为5∶1,晶化温度为400℃,晶化时间为5 min,硅铝摩尔比为2.5∶1。
Using fly ash as raw material, fly ash zeolite was synthesized by alkali fusion and supercritical hydrothermal synthesis. The effects of alkali type, calcination temperature and soda ash ratio on the activation of fly ash were investigated. The effects of alkali temperature, alkali concentration, crystallization time, Ratio and molar ratio of silica to alumina on the formation of fly ash zeolite to optimize the synthesis conditions. The results showed that the activation of fly ash was the best when Na_2CO_3 was used as activator, and the ratio of alkali to cement was 1.2:1. The activation of fly ash was the best at 850 ℃ for 3 h. The mixture of fly ash and water pretreated by alkali melting was mixed with water in supercritical water and heat The optimum calcination conditions were distilled water, the ratio of liquid to solid was 5:1, the crystallization temperature was 400 ℃, the crystallization time was 5 min and the molar ratio of silica to alumina was 2.5:1.