摘要
应用多晶X射线方法测定了高温(540℃)焙烧后GaZSM-11沸石的晶体结构,其空间群为D_(2d)~9-I_(4m2)^-。GaZSM-11沸石有两个相互垂直半切交直通道,两孔道都近似为正十元环,平均直径为5.33(4)。在GaZSM-11沸石骨架中,Ga原子取代骨架Si原子后主要分布在T(1)与T(2)两套不等效点系上,而且相应产生了两种阳离子位。处于孔道内的阳离子分布在两种阳离子位上,靠近通道内壁与四面体上氧原子形成三配位体。此外,根据结构测定结果,详细探讨了质子酸的产生与分布,以及TBA^+阳离子的导向作用。和ZSM-5沸石在结构、性能及合成方面进行了对比。
The crystal Structure of GaZSM-11 zeolite (calcined at 540℃) was examined by X-ray diffraction powder method. Its Space group is D29d-I4m2 and the crystal parameters are α=b=20.073(4)A°,c= 13.403(3)A°. The framework of GaZSM-11 zeolite possesses two perpendicular and half-crossed channels, whose holes are nearly regular ten-membered ring, the average diameter is 5.33(4)A°. In the GaZSM-11 zeolite framework, Ga atoms replacing framework Si atoms are distributed at two sets of unequal point systems T(1) and T(2). It is considered that the template-directing effect of TBA+ cations includes its chemical exciting effect on SBU and its template-supporting effect on the framewoik, and that strong acid sites are GaO7 telrahedra at T(1) and weak acid sites are GaO7 tetrahedra at T(2). The structure, properties and synthesis of ZSM-11 zeolite are compared with those of ZSM-5 zeolite, and no ny better characteristics of ZSM -11 are observed.
基金
国家自然科学基金
