Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (06): 1136-1142.doi: 10.3866/PKU.WHXB20090630

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Location of Al and Acid Strength of Brφnsted Acid in Beta Zeolite

SUN Xiu-Liang, HUANG Chong-Pin, ZHANG Jie, CHEN Biao-Hua   

  1. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China
  • Received:2009-01-13 Revised:2009-03-14 Published:2009-06-05
  • Contact: HUANG Chong-Pin E-mail:huangcp@mail.buct.edu.cn

Abstract:

Density functional theory (DFT) was applied to study the distribution of framework aluminum atoms at nine inequivalent T sites and the acidity of Brφnsted acid sites in Beta zeolite. The calculation was carried out at B3LYP/6-31G (d,p) level based on the 8Tclustermodel. According to the calculated Al/Si substitution energies, (Al, H)/Si substitution energies, proton affinities and the adsorption energies of ammonia (NH3), we propose that the most favorable sites for Al substitution and Brφnsted acid sites are at the T5 and T6 sites. The acidity of Al5-O14-Si9 is the highest among the preferred Brφnsted acid sites and the Al7-O3-Si1 site is the lowest.

Key words: Beta zeolite, Brφnsted acid, Density functional theory

MSC2000: 

  • O641