Acidity of MCM-58 and MCM-68 zeolites in comparison with some other 12-ring zeolites

0341551 - ÚFCH JH 2011 RIV NL eng J - Journal Article
Gil, B. - Košová, Gabriela - Čejka, Jiří
Acidity of MCM-58 and MCM-68 zeolites in comparison with some other 12-ring zeolites.
Microporous and Mesoporous Materials. Roč. 129, 1-2 (2010), s. 256-266. ISSN 1387-1811. E-ISSN 1873-3093
R&D Projects: GA ČR GA104/07/0383; GA MPO FT-TA3/080
Institutional research plan: CEZ:AV0Z40400503
Keywords : MCM-58 * MCM-68 * Bronsted and Lewis acid centres
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.220, year: 2010

Two novel zeolites MCM-58 and MCM-68 with 12-ring channels and containing the cages in the structure were investigated with respect to their acidic properties and compared with other two 12-ring zeolites, namely Beta and ZSM-12. The main objective was to characterize the accessibility and acid strength of Lewis and Bronsted sites using FTIR spectroscopy. Pyridine adsorption allowed for quantification of Bronsted and Lewis acid centres and pointed out that while in the structure of MCM-58 nearly all Al atoms form acidic Si-OH-Al bridges, only about half of Al is a source of the Bronsted acidity in MCM-68. The special attention was devoted to the origin and location of the hydrogen-bonded OH groups in the MCM-58 zeolite. The frequency lowering is caused by the across-the-ring interaction with the oxygen atom and not by the interaction with the nearby OH groups, as proved by high temperature activation and deuteration experiments.
Permanent Link: http://hdl.handle.net/11104/0184493