Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (04): 606-610.doi: 10.3866/PKU.WHXB20090401

• ARTICLE • Previous Articles     Next Articles

Resonance Raman Spectrumof Fe-AlPO4-5 Zeolite

 SUN Ke-Ju, LI Wei-Xue, FENG Zhao-Chi, LI Can   

  1. State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning Province, P. R. China; Graduate University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2008-11-25 Revised:2008-12-24 Published:2009-03-31
  • Contact: LI Wei-Xue, LI Can E-mail:wxli@dicp.ac.cn;canli@dicp.ac.cn

Abstract:

Resonance Raman spectrum results from the study of silica zeolites that contain transition metals by density functional theory (DFT) calculations were extended successfully to an aluminum phosphate zeolite system. Based on the study of the resonance Raman spectrum of Fe-ZSM-5 and DFT calculations of Fe-AlPO4-5, we predicted the presence of four vibrational bands at 1190, 1130, 1000-1050 and 600 cm-1 in the resonance Raman spectrum of Fe-AlPO4-5. Experimentally those four bands were found at 1210, 1130, 1050, and 630 cm-1 in the Raman spectrum of Fe-AlPO4-5, excited by a 244 nmlaser, and were assigned to the framework Fe species. The resonance Raman spectrum of Fe-AlPO4-5 is similar to that of the Fe-ZSM-5 zeolite since both zeolites have similar tetrahedrally coordinated Fe species in the framework. However, the vibrational frequencies of Fe-AlPO4-5 are higher than those of Fe-ZSM-5 because of the higher force constant of oxygen in Al—O—P than in Si—O—Si. Furthermore, the effect of the electrostatic attraction between the PO4 tetrahedron and the AlO4 tetrahedron is found to be important to the vibrational frequencies.

Key words: Density functional theory, Fe-AlPO4-5, Resonance Raman spectroscopy

MSC2000: 

  • O641