A theoretical study of hydrothermal stability of P-modified ZSM-5 zeolites

• 来源期刊: 中国科学B辑（英文版）
• 年，卷（期）: 2009,（3）
• 页码范围: 282-287
• 页数: 6页
• 语种: 英文
• DOI: 10.1007/s11426-009-0053-8

摘要

Density functional theory was employed to study the hydrothermal stability of P-modified ZSM-5 zeolites using cluster models. The calculations of hydrolysis energies indicated that the introduction of phos-phorus increases the hydrothermal stability of ZSM-5 zeolites. The initial paths of dealumination were studied with explicit water molecules. It was found that the framework AI-O coordination bond can be replaced by coodination bonds between water molecules and the aluminium. One to three water mole-cules can form coordination bonds with framework AI and release energies. The P-modification restrain the dealumination. The calculated 27AI NMR chemical shifts for the obtained structures are consistent with the experimental measurements.