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Discovery and Synthesis Optimization of Isoreticular Al(III) Phosphonate-Based Metal-Organic Framework Compounds Using High-Throughput Methods
Published on: October 6, 2023
Tracking the structural changes in pure and heteroatom substituted aluminophosphate, AIPO-18, using synchrotron based
Martin Martis1, Andrew J Smith, Chiu Tang
1University College London, Department of Chemistry, 20 Gordon Street, London, WC1H 0AJ, UK.
Physical Chemistry Chemical Physics : PCCP
|June 12, 2013
Summary
Structural changes in nanoporous zeolitic solids like AlPO-18 were studied during template removal via calcination. Heteroatom type influences structural evolution, with cell volume contracting upon template and water removal.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Catalysis
Background:
- Nanoporous zeolitic solids are crucial in catalysis.
- AlPO-18, SAPO-18, and their heteroatom-substituted variants are important materials.
- Calcination is essential for activating these materials as catalysts.
Purpose of the Study:
- To investigate structural transformations during organic template removal from small-pore zeolitic solids.
- To understand the role of heteroatoms in these structural changes.
- To elucidate the impact of calcination on the structural integrity of AlPO-18, SAPO-18, and related materials.
Main Methods:
- Time-resolved High Resolution Powder Diffraction (HRPD) at various temperatures.
- High Energy X-ray Diffraction (HEXRD) to probe local atomic environments.
- In-situ structural analysis during thermal treatment (calcination).
Main Results:
- Structural changes are dependent on the type of heteroatom present.
- HRPD revealed lattice parameter changes during water and template removal.
- HEXRD indicated changes in near-neighbor distances and coordination of water to Al(III) ions.
- A contraction in cell volume was observed at elevated temperatures post-template removal, with minimal change in nearest neighbor distances.
Conclusions:
- The heteroatom composition dictates the structural response to thermal template removal.
- Water molecules coordinated to Al(III) ions are present in as-synthesized materials.
- Despite cell volume contraction, the local atomic structure (first and second neighbor distances) remains largely intact after template and water removal.
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