物理化学学报 >> 1997, Vol. 13 >> Issue (09): 780 -785 .doi: 10.3866/PKU.WHXB19970903

研究论文 上一篇    下一篇

用固体核磁共振研究Al/P>1的磷酸铝分子筛AlPO4-5

邓风,董晋湘,杜有如,叶朝辉   

  1. 中国科学院武汉物理研究所 波谱与原子分子物理国家重点实验室,武汉 430071|太原工业大学精细化工研究所,太原 030024
  • 收稿日期:1997-01-06 修回日期:1997-03-03 发布日期:1997-09-15
  • 通讯作者: 邓风

Solid-state NMR Studies on AlPO4-5 Molecular Sieve with Al/P>1

Deng Feng,Dong Jin-Xiang,Du You-Ru,Ye Chao-Hui   

  1. Laboratory of Nuclear Magnetic Resonance and Atomic and Molecular Physics,Wuhan Institute of Physics,The Chinese Academy of Sciences,Wuhan 430071|Tiayuan University of Technology,Taiyuan 030024
  • Received:1997-01-06 Revised:1997-03-03 Published:1997-09-15
  • Contact: Deng Feng

摘要:

用固体高分辨核磁共振(NMR)方法对一系列Al/P>1的新型磷酸铝分子筛AlPO4-5中磷和铝的结构状态及联结方式进行了研究,27Al和31P NMR都给出了在分子筛骨架中存在有Al-O-Al联结方式的实验证据,寓示着在该体系中P和Al的排布不再遵循Loewenstein规则.

关键词: AlPO4-5分子筛, Al/P>1, Al-O-Al相连, NMR

Abstract:

Solid-state NMR spectroscopy was employed to investigate the coordination state of P and Al, as well as their linkages in a series of newly synthesized alunilnophosphate molecular sieve AlPO4-5 with Al/P>1. Both 31P and 27Al NMR provides evidence that Al-O-Al linkages are present in the framework of these molecular sieves, which implies that the ordering arrangement of P and Al does not obey the well-known Loewenstein rule. Apart from the usually observed NMR signals, a broad peak at ca. δ=10 is present in the 27Al MAS spectra of the calcined and dehydrated AlPO4-5 molecular sieves. Due to its large second-order quadrupole shift, an isotropic chemical shift of ca. δ=38 was estimated. Hence, we attribute this signal to 4-coordinated aluminum: Al[nAl, (4-n)P )](n=1,2,3,4). Similarly, an additional broad signal at δ=-24 was observed in the corresponding 31P MAS spectra and is due to the P coordination state in which its second coordinated shell contains Al: P[nAl, (4-n)P]second shell (n=1,2,3,4).

Key words: AlPO4-5, Al/P>1;Al-O-Al linkage, 31P and 27Al NMR