AINaZSM-5 zeolites. Part 1. A study with i.r. spectroscopy and MAS n.m.r. (27Al and 1H)

✍ Scribed by T. Romotowski; J. Komorek; V.M. Mastikhin; A.V. Nosov

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 510 KB
• Volume: 11
• Category: Article
• ISSN: 0144-2449
• DOI: 10.1016/s0144-2449(05)80123-x

✦ Synopsis

The direct treatment of NaZSM-5 zeolite with aluminum salt solution without an intermediate ammonium form was applied to obtain as neutral AINaZSM-5 zeolites as possible. It was possible to prepare very weakly acidic, or almost neutral samples, using the parent zeolite neutralized by an exchange with NaCl solution prior to the treatment with AICIB solution in the presence of an acetate buffer. As a test reaction, transformation of propene and methanol wzre performed. "AI and 'Ii n.m.r. studies confirmed that the preparation of aproton forms of AINaZSM-5 zeolites is difficult, because AlClz solution treatment is normally accompanied by the exchange of Na ions for protons. Most of the aluminum atoms inserted exist in the zeolite channels as various forms of "aluminum oxide/ hydroxide" complexes. Aluminum occurs in strongly distorted tetrahedral or octahedral surroundings, and the quantity of Al as hexa-aqua-complexes is small and is independent from the concentration of Al.