【摘要】 应用多晶X射线衍射法,研究了合成时以三乙胺为模板剂,晶粒维度为几个μm的AlPO₄-5分子筛结构,并经Rietveld法修正。对结构的测定得出,该分子筛的骨架几何构型与Bennett等报道的合成时以TPAOH为模板剂,晶粒维度为30×180μm,用单晶法测得的AlPO₄-5的结构相似,但骨架中T₁-O的平均间距上升为1.64（?）（T₁对应于Bennett文中的P）。T₂-O的平均间距下降为1.64（?）（T₂对应于Bennett文中的Al）。因此可得出骨架中T₁和T₂这二个位置均为P、Al无序地占有,从而破坏了分子筛在[001]方向的极性。另一方面,从结构的测定发现六方柱的中心可能成为具有高配位的阳离子位置。因此,AlPO₄-5型的结构允许存在Al/P≠1或Si部分取代P而造成带负电荷的骨架。更多还原

【Abstract】 The crystal structure of APO-5 type molecular sieve with a dimension of several μm synthesized by taking triethylamine as the template was determined by X-ray diffraction for polycrystalline materials and the parameters were refined by Rietveld method. The structure of the framework is quite similar to that reported by Bennett and coworkers. They have synthesized a monocrys tal of APO-5 type molecular sieve with dimensions of 30 × 180μm by taking TPAOH as the template. However, the average bond length of T(1)-O in the framework of ours is increased to 1.64A, and that of T(2) O is reduced to 1.64A (T(1) and T(2) correspond to P and Al atoms in Bennett’s paper, respectively). This evidences that the site T(1) and T(2)are occupied in disorder by P and A1, so the polarity of the APO-5 in(100)direction is destroyed.It was found that there are sites in the 6-ring channel which should be occupied by cations with high coordination. It is possible to modify the structure to make the framework with negative charge by changing the Al/P ratio from unity to some other value or replacing some of phosphorous atoms by silicon atoms in the framework,更多还原