物理化学学报 >> 2011, Vol. 27 >> Issue (08): 1823-1830.doi: 10.3866/PKU.WHXB20110733

理论与计算化学 上一篇    下一篇

磷在P-ZSM-5沸石中存在的形态

杨静, 孙迎新, 赵立峰, 孙淮   

  1. 上海交通大学化学化工学院, 上海 200240
  • 收稿日期:2011-04-29 修回日期:2011-05-18 发布日期:2011-07-19
  • 通讯作者: 孙淮 E-mail:huaisun@sjtu.edu.cn
  • 基金资助:

    国家自然科学基金(21073119), 国家重点基础研究发展计划(973) (2007CB209701)和上海石油化工研究院资助项目

Phosphorous Moieties in P-ZSM-5 Zeolites

YANG Jing, SUN Ying-Xin, ZHAO Li-Feng, SUN Huai   

  1. School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
  • Received:2011-04-29 Revised:2011-05-18 Published:2011-07-19
  • Contact: SUN Huai E-mail:huaisun@sjtu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073119), National Key Basic Research Program of China (973) (2007CB209701) and Research Program from Shanghai Research Institute of Petrochemical Technology, China.

摘要:

用密度泛函理论和ONIOM (our own N-layer integrated molecular orbital molecular mechanics)方法研究磷改性的ZSM-5沸石中含磷基团的可能存在形态. 计算的反应焓和自由能数据表明P-ZSM-5沸石中以磷进入骨架和在骨架外的形成磷酸根离子对是合理的稳定结构. 而且, 计算结果表明离子对模型F和G更适合在室温下存在, 磷进入骨架的酸性结构C'在高温下更稳定, 而磷进入骨架的结构C对温度变化不敏感. 计算得到的27Al, 31P, 29Si化学位移、酸性的变化趋势和结构参数与相关实验数据吻合.

关键词: H-ZSM-5沸石, 磷改性, ONIOM方法, 密度泛函理论

Abstract:

Phosphorus modified ZSM-5 (P-ZSM-5) zeolite was investigated using quantum mechanics density functional theory and our own N-layer integrated molecular orbital molecular mechanics method (ONIOM). Extra-framework phosphate and in-framework moieties containing phosphorus were found to be plausible local structures in P-ZSM-5 zeolites based on the calculated heats of formation and the free energy data from the hypothetical reactions. Furthermore, we find that the cationic moieties are favored at room temperature. The in-framework acidic moieties are more stable at high temperatures and the stability of the in-framework phosphorus moieties is insensitive to temperature changes. The calculated 27Al, 31P, and 29Si chemical shifts, acidity changes, and structural parameters agree well with the known experimental observations.

Key words: H-ZSM-5 zeolite, P-modification, ONIOM method, Density functional theory

MSC2000: 

  • O641