Testing of the Lewis acidity of H-Y and HZSM-5 zeolites with 15N n.m.r. of adsorbed N2O

✍ Scribed by V.M. Mastikhin; I.L. Mudrakovsky; S.V. Filimonova

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 378 KB
• Volume: 10
• Category: Article
• ISSN: 0144-2449
• DOI: 10.1016/s0144-2449(05)80318-5

✦ Synopsis

The Lewis acidity of H-Y and HZSM-5 zeolites has been studied using lSN n.m.r, of adsorbed N20. It follows from lSN n.m.r, data that in H-Y zeolites a variety of Lewis acidic sites having different strengths of acidity is present. The number of the strongest Lewis sites is about 20-30 i~mole/g, i.e., about 102 times less compared with the total quantity of extralattice aluminum atoms. The number of the "strong" and "weak" Lewis sites in H-Y zeolites depends on the types of treatment. The strong Lewis sites are found in the samples treated under shallow-bed conditions. The deep-bed treatment results in decreasing of the concentration of the strongest Lewis acidic sites.

For HZSM-5 zeolites, the quantity of the strong Lewis acidic sites is the same order of magnitude as the number of the extralattice aluminum atoms.