六亚甲基亚胺在MCM-22分子筛合成中的导向作用及分解行为研究

对以六亚甲基亚胺为模板剂合成MCM-22分子筛的方法进行了优化,并对模板剂在合成中的作用及焙烧分解行为进行了研究。结果表明,采用合适的水与硅物质的量比和晶化温度能有效降低六亚甲基亚胺用量;六亚甲基亚胺在MCM-22分子筛合成过程中起结构导向和平衡电荷的作用;在干燥焙烧过程中无气相六亚甲基亚胺外排,烟气中含氮化合物以NH₃、NO和NO₂为主。

Research on structure directing effect and decomposition behavior of hexamethyleneimine in synthesis of MCM-22 molecular sieves

The synthesis methods of MCM-22 molecular sieves by using hexamethylenimine (HMI) as the template were optimized.The effect of the template HMI in the hydrothermal synthesis of MCM-22 molecular sieves and its decomposition during dryness and calciantion were investigated.The results showed that the dosage of HMI was effectively reduced by adopting appropriate H₂O/SiO₂ molar ratio and crystallization temperature during the synthesis of MCM-22 molecular sieves.Hexamethylenimine acted as the structure directing agent and protonated HMI resided in the 10 member ring to balance the framework charge.During drying and calcining the as-prepared MCM-22 molecular sieves,HMI was not detected in flue gas,and the nitrogen compounds in flue gas mainly were NH₃,NO and NO₂.