Abstract:

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.

Key words: Aluminophosphate molecular sieve, Distortion, Standard deviation, Continuous shape measure(CShM), Heteroatom-substitution