磷酸铝分子筛中骨架扭曲度与杂原子取代的关系

采用计算机模拟方法对AFI, AEL, ATO, SBS, SBE, SBT, JRY和MAPO-CJ69等磷酸铝分子筛的骨架进行了几何优化, 通过计算这些骨架结构中AlO₄和AlP₄四面体的Al-O, O-O, Al-P和P-P各键长的标准偏差及AlO₄和AlP₄四面体的连续形状度量(CShM), 得到了这些分子筛骨架中四面体的扭曲度. 通过对比发现, 具有较大扭曲度的骨架在实验中往往需要引入杂原子以稳定整个结构, 且杂原子优先进入骨架中扭曲度大的位置; 而扭曲度较小的骨架结构无需引入杂原子就能够合成出来.

Relationship Between Framework Distortion and Heteroatom-substitution in Aluminophosphate Molecular Sieves

Aluminophosphate molecular sieve frameworks AFI, AEL, ATO, SBS, SBE, SBT, JRY and MAPO-CJ69 were optimized by means of computer simulation methods. The standard deviations of Al—O, O—O, Al—P, and P—P distances in AlO4 and AlP4 tetrahedra, as well as their continuous shape measure(CShM) values were calculated. Calculation results show that the introduction of heteroatoms is necessary for the formation of molecular sieve frameworks with high distortions. In addition, Heteroatoms occupy the most distorted tetrahedra sites. On the contrary, zeolite frameworks with low distortions can be synthesized without the addition of heteroatoms. These results agreed well with the experimental results.