27Al-n.m.r. characterization of natural and synthetic zeolites

Facile Preparation of Ammonium Molybdophosphate/Al‐MCM‐41 Composite Material from Natural Clay and Its Use in Cesium Ion Adsorption

“…The splitting may be caused by the distorted coordination of the hydrated samples. [36] For 30 %AMP/Al-MCM-41, only a single resonance with a chemical shift of ca. 53 ppm was observed ( Figure 6, b); this indicates that the Al 3+ ions were successfully incorporated into the tetrahedral framework.…”

Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

“…A thoroughly studied example is the coordination number of framework aluminum. Significantly different spectral positions were detected for four-coordinated and six-coordinated aluminum, respectively, in hydrated aluminosilicate zeolites [18,25,26,27,28].…”

“…Aluminum atoms in zeolite frameworks are tetrahedrally coordinated to four oxygen atoms, and give rise to resonance frequencies at between 55 ppm and 65 ppm, depending on the magnetic field strength, and the materials investigated [5,28].…”

“…Chemical modifications of the zeolite framework, such as dealumination [18,26,29], and dehydroxylation [28,30], cause more shielded nuclear environments, which are associated with 6-coordinated aluminum, located on the exterior of the zeolite framework. The observation of a distinct 27A1signal associated with 6-coordinated extraframework aluminum provides a highly sensitive analytical tool for intimate structural studies of the mechnisms of chemical modifications of the zeolite inner 9 surface [18,25,29,30,31].…”

Catalyst for ultra-low sulfur and aromatic diesel

“…The 27 Al NMR was used to determine the structure of the support (Ti-Al) based on the method described by Nagy et al [10]. The spectrum provides information on the different type of aluminum structures in the support (tetrahedral-octahedral coordination).…”