Tracking Lattice Distortion Induced by Defects and Framework Tin in Beta Zeotypes
Yunfei Bai1,2, Esben Taarning1, Mahika Luthra3
1Topsoe A/S, Haldor Topso̷es Allé 1, 2800 Kongens Lyngby, Denmark.
Summary
Powder X-ray diffraction (PXRD) reveals a strong link between tin concentration, defects, and crystal structure in Sn-Beta materials. This method offers a fast way to assess structural changes and catalytic potential in zeotypes.
Area of Science:
- Materials Science
- Crystallography
- Catalysis
Background:
- Zeotype materials, such as Sn-Beta, are crucial in catalysis.
- Understanding their crystal structure and defect sites is key to optimizing performance.
- Powder X-ray diffraction (PXRD) is a primary tool for structural analysis.
Purpose of the Study:
- To investigate the crystal structure of Sn-Beta materials using PXRD.
- To establish correlations between lattice parameters, tin concentration, and defects.
- To explore the influence of preparation methods (hydrothermal vs. postsynthetic) on structure.
Main Methods:
- Utilizing powder X-ray diffraction (PXRD) with lattice parameter refinement.
- Applying a novel semiempirical PXRD model with a reduced tetragonal unit cell.
- Conducting density functional theory (DFT) studies for theoretical validation.
Main Results:
- A robust correlation was found between lattice parameters and tin/defect concentration.
- Postsynthetic (PT) Sn-Beta samples showed expanded unit cells due to higher defect density.
- Hydrothermal (HT) Sn-Beta samples exhibited lattice distortion directly related to framework tin density.
- DFT studies confirmed the observed trends in lattice distortion upon tin substitution.
Conclusions:
- PXRD is a rapid and effective method for characterizing framework defects and heteroatom density in zeotypes.
- This approach enables monitoring of structural changes and evaluation of catalytic properties.
- The findings provide insights into tailoring Sn-Beta materials for specific catalytic applications.
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