(Al,B)-MCM-41分子筛在气相贝克曼重排反应中的应用

Application of Vapor Phase Beckmann Rearrangement of Cyclohexanone Oxime over(Al,B)-MCM-41 Zeolite

用改进的快速合成法制备了2个系列的催化剂,并用XRD、N2吸附、FT-IR、27Al MAS、NMR和NH3-TPD等手段对其表征,用环己酮肟气相贝克曼重排反应评价其活性。结果表明,合成的催化剂具有MCM-41的结构,铝和硼进入到分子筛的骨架中。当n(Al)/n(B)的值一定时,随着铝和硼添加量的增多,分子筛的弱酸性位的数量增多,己内酰胺的选择性升高。当添加的铝和硼的总量一定,随着铝含量的减少,相应硼的量增加,己内酰胺的选择性升高。只添加硼时环己酮肟转化率和己内酰胺的选择性均很低。(Al,B)-MCM-41分子筛在气相贝克曼重排反应中的活性主要与骨架中的铝和硼的数量以及弱酸位的数量有关。

Two series of catalyst were synthesized by the modified fast synthesis method and characterized by XRD, nitrogen physisorption, FT-IR, 27A1 MAS NMR, and NH3-TPD. The catalysts were used for vapor phase Beckmann rearrangement of cyclohexanone oxime. The XRD results indicate that the synthe- sized catalysts exhibit the typical mesostructural of MCM-41. The FT-IR results conforme that aluminium （A1） and boron（B） atoms are coordinated in the framework of zeolite. When the mole ratio of A1/B e- quals 0.5, with increasing the amount of A1 and B content, more weak acid sites are produced. And more weak acid sites are favorable to form caprolactam. When the mole ratio of Si/M equals 10, the se- lectivity of caprolaetam increased with increasing B content. The catalyst has low activity by adding B on- ly in the MCM-41. The activity of （A1, B）-MCM-41 is mainly associated with weak acid site.