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Memory Effect on a LDH/zeolite A Composite: An XRD In Situ Study
Breno G P Bezerra1, Lindiane Bieseki1, Mariele I S de Mello1
1Molecular Sieves Laboratory LABPEMOL, Chemistry Institute, Federal University of Rio Grande do Norte UFRN, Natal 59078-970, RN, Brazil.
Materials (Basel, Switzerland)
|April 30, 2021
Summary
The lamellar double hydroxide-like (LDH)/zeolite A composite exhibits a memory effect, allowing it to be calcined and rehydrated. Optimal heat treatment for the LDH in the composite involves 300 °C in an inert atmosphere.
Area of Science:
- Materials Science
- Solid State Chemistry
- Nanomaterials
Background:
- Hydrotalcite-type compounds, known as layered double hydroxides (LDHs), possess unique structural properties.
- Zeolite A is a synthetic porous material with applications in adsorption and catalysis.
- Composite materials combining LDHs and zeolites offer synergistic properties for advanced applications.
Purpose of the Study:
- To investigate the memory effect in lamellar double hydroxide-like (LDH)/zeolite A composite materials.
- To analyze the structural changes and rehydration capabilities of LDH-based materials after thermal treatment.
- To determine the optimal conditions for heat treatment of LDH/zeolite A composites.
Main Methods:
- In situ X-ray Diffraction (XRD) was employed to study structural transformations.
- Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used for morphological and compositional analysis.
- Multiple thermal treatments under different atmospheres (O2, He) and temperatures (300 °C, 500 °C) followed by rehydration were performed on Al,Mg-LDH, Al,Mg-LDH/ZA composites, and physical mixtures.
Main Results:
- The LDH phase within the Al,Mg-LDH/ZA composite demonstrated a significant memory effect, confirming its ability to be calcined and subsequently rehydrated.
- The composite structure remained stable under specific thermal treatments, indicating potential for regeneration.
- SEM and EDS analyses provided insights into the material's morphology and elemental distribution post-treatment.
Conclusions:
- The lamellar double hydroxide-like (LDH)/zeolite A composite material exhibits a notable memory effect, enabling calcination and rehydration cycles.
- The optimal heat treatment for the LDH component within the composite involves a temperature of 300 °C under an inert atmosphere (He).
- These findings suggest the potential for developing regenerable LDH/zeolite A materials for various applications.
