| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Dawson, Daniel M.
University of St Andrews
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (15/15 displayed)
- 2024Site-directed cation ordering in chabazite-type Al x Ga 1–x PO 4 -34 frameworks revealed by NMR crystallographycitations
- 2024Site-directed cation ordering in chabazite-type AlxGa1–xPO4-34 frameworks revealed by NMR crystallographycitations
- 2024Site-directed cation ordering in chabazite-type Al x Ga 1− x PO 4 -34 frameworks revealed by NMR crystallographycitations
- 2024Site-directed cation ordering in chabazite-type AlxGa1−xPO4-34 frameworks revealed by NMR crystallographycitations
- 2023Synthesis of FeAPO-34 molecular sieve under ionothermal conditioncitations
- 2022Synthesis of FeAPO-34 molecular sieve under ionothermal conditioncitations
- 201817 O solid-state NMR spectroscopy of A 2 B 2 O 7 oxides:quantitative isotopic enrichment and spectral acquisition?citations
- 201817O solid-state NMR spectroscopy of A2B2O7 oxidescitations
- 2017A gel aging effect in the synthesis of open-framework gallium phosphatescitations
- 2017Assembly-diassembly-organization-reassembly synthesis of zeolites based on cfi-type layerscitations
- 2016Phase Composition and Disorder in La2(Sn,Ti)2O7 Ceramics: New Insights from NMR Crystallography
- 2016Phase composition and disorder in La2(Sn,Ti)2O7 ceramicscitations
- 2015Combined theoretical and experimental investigations of porous crystalline materials
- 2011A co-templating route to the synthesis of Cu SAPO STA-7, giving an active catalyst for the selective catalytic reduction of NO
- 2011A co-templating route to the synthesis of Cu SAPO STA-7, giving an active catalyst for the selective catalytic reduction of NOcitations
Places of action
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article
A gel aging effect in the synthesis of open-framework gallium phosphates
Abstract
The templated zeolite-analogue GaPO-34 (CHA structure type) crystallises from a gel precursor Ga<sub>2</sub>O<sub>3</sub> : 2H<sub>3</sub>PO<sub>4</sub> : 1HF : 1.7SDA : 70H2O (where SDA = structure directing agent), treated hydrothermally for 24 hours at 170 °C using either pyridine or 1-methylimizadole as SDA and one of either poorly crystalline ε-Ga<sub>2</sub>O<sub>3</sub> or γ-Ga<sub>2</sub>O<sub>3</sub> as gallium precursor. If the same gels are stirred for periods shorter than 2 hours but treated under identical hydrothermal conditions, then a second phase crystallises, free of GaPO-34. If β-Ga<sub>2</sub>O<sub>3</sub> is used as a reagent only the second phase is found to crystallise, irrespective of gel aging time. The competing phase, which we denote GaPO-34A, has been structurally characterised using synchrotron powder X-ray diffraction for the pyridine material, GaPO-34A(pyr), and using single-crystal X-ray diffraction for the 1-methylimiazole material, GaPO-34A(mim). The structure of GaPO-34A(pyr), P[1 with combining macron], a = 10.22682(6) Å, b = 12.09585(7) Å, c = 13.86713(8) Å, α = 104.6531(4)°, β = 100.8111(6)°, γ = 102.5228(6)°, contains 7 unique gallium sites and 6 phosphorus sites, with empirical formula [Ga<sub>7</sub>P<sub>6</sub>O<sub>24</sub>(OH)<sub>2</sub>F<sub>3</sub>(H<sub>2</sub>O)<sub>2</sub>]·2(C<sub>5</sub>NH<sub>6</sub>). GaPO-34A(mim) is isostructural but is modelled as a half volume unit cell, P[1 with combining macron], a = 5.0991(2) Å, b = 12.0631(6) Å, c = 13.8405(9) Å, α = 104.626(5)°, β = 100.346(5)°, γ = 101.936(4)°, with a gallium and a bridging fluoride partially occupied and two partially occupied SDA sites. Solid-state <sup>31</sup>P and <sup>71</sup>Ga NMR spectroscopy confirms the structural complexity of GaPO-34A with signals resulting from overlapping lineshapes from multiple Ga and P sites, while <sup>1</sup>H and <sup>13</sup>C solid-state NMR spectra confirm the presence of the protonated SDA and provide evidence for disorder in the SDA. The protonated SDA is located in 14-ring one-dimensional channels with hydrogen bonding deduced from the SDA nitrogens to framework oxygen distances. Upon thermal treatment to investigate SDA removal, structure collapse occurs, which may be due the large number of bridging hydroxides and fluorides in the as-made material, and the unequal amounts of gallium and phosphorus present.