Characterization of AlPO4-14 by magic-angle-spinning nuclear magnetic resonance spectroscopy and thermoanalytical and adsorption measurements

Abstract

AIP0,-14 has been prepared using piperidine as templating agent. Uniform crystals of tabular habit were obtained. By thermoanalytical measurements of the as-synthesized sample t h e content of occluded piperidine was determined and its degradation was followed. From the 31P MAS NMR spectra it follows that there should exist at least three non-equivalent sites in t h e framework of calcined AIP0,-14. Completely reversible changes in t h e "AI and 31P M A S N M R spectra were found in dehydration/hydration cycles. T h e relative small pore diameter of AIP0,-14 (ca. 0.4 nm) prohibits the adsorption of n-alkanes. From t h e adsorption isotherms of methanol and water the saturation capacities were determined to be 0.17 and 0.27 cm3 g-', respectively.

Structure and NMR assignment in calcined and as-synthesized forms of AlPO-14: a combined study by first-principles calculations and high-resolution 27Al–31P MAS NMR correlation

“…To prepare calcineddehydrated AlPO-14, either as-synthesized material was heated in air for 3 hours at 600 1C. The materials were determined to be phase pure by XRD, with the data being consistent with either the structure elucidated by Broach et al 21,22 (ipa-and calcined-dehydrated or in qualitative agreement with those presented by Zibrowius et al 3 (pip-AlPO-14).…”

“…In addition to isopropylamine, AlPO-14 can also be synthesized with piperidine as the template molecule (pip-AlPO-14) and an early NMR study was performed by Zibrowius et al 3 The exact structure of pip-AlPO-14, the number of template molecules in the unit cell, and the ionic state of the template are not known. 3 The 27 Al and 31 P MAS NMR spectra of pip-AlPO-14 are shown in Fig. 2e and f.…”

“…In particular, AlPO-14 has been intensively investigated by high-resolution magic-angle spinning (MAS) NMR spectroscopy and the 27 Al and 31 P NMR parameters are well documented in the literature. [3][4][5][6][7][8][9][10][11] Recently, we have used 27 Al multiple-quantum MAS (MQMAS) 12,13 and satellitetransition MAS (STMAS) [14][15][16] NMR experiments to provide evidence for extensive microsecond-timescale dynamics 17 in two as-synthesized forms of AlPO-14 and to show that such dynamics are absent in the calcined-dehydrated form. 18 This appears to be a promising and possibly general approach for studying host-guest interactions in microporous solids with the long-term aim of better understanding their sorption and catalytic properties.…”

Characterisation of Zeolitic Materials with a HEU-Type Structure Modified by Transition Metal Elements: Definition of Acid Sites in Nickel-Loaded Crystals in the Light of Experimental and Quantum-Chemical Results

“…A reversible structural transformation of this kind has not been reported previously for zeolites, but it is well known for other microporous materials, such as the zeotype AlPO 4 . [50] Chemisorption of the Lewis-type base Py on the activated NiHEU is apparently associated with coordination processes affording relevant Ni 2 coordination compounds throughout the crystals of the material (intra-zeolite and surface complexes). The powder XRD patterns of NiHEU-Py/R (Figure 8) demonstrated that the crystal structure of the zeolite is essentially preserved during dehydration/activation followed by Py sorption and rehydration.…”

The Potassium Aluminum Phosphate KAl(HPO4)2·H2O: X-Ray Diffraction, Neutron-Scattering, and Solid-State NMR Characterization

“…In addition, aluminum orthophosphates, AlPO , and modified products are characterized by solid-state NMR with respect to their catalytic properties (4)(5)(6)(7). In this paper we present a complete single-crystal X-ray structure determination of KAl with phosphate solution as described above.…”