Direct Evidence for the Nonrandom Nature of Al Substitution in Zeolite ZSM-5: An Investigation by 27Al MAS and MQ MAS NMR

Incorporation of Al atoms in particular sites in the ZSM-5 structure is governed by the Si/Al ratio during synthesis, and their distribution over the twelve types of tetrahedral sites (T1–T12) during crystallization occurs in a nonrandom manner according to the results of 27Al MAS NMR measurements on a series of as-made ZSM-5 zeolites with Si/Al=14–250. Further support for this conclusion was provided by 27Al MQMAS spectra (see picture) simulated with X-ray diffraction data. Supporting information for this article is available on the WWW under http: //www. wiley-vch. de/contents/jc₂002/2002/z17357ₛ. pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.