Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (08): 1823-1830.doi: 10.3866/PKU.WHXB20110733

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

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.

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