A Novel Integrated X-Ray Powder Diffraction (XRPD) and Molecular Dynamics (MD) Approach for Modelling Mixed-Metal (Zn, Al) Layered Double Hydroxides (LDHs).

ChemInform ◽  
2006 ◽  
Vol 37 (11) ◽  
Author(s):  
Giuseppe M. Lombardo ◽  
Giuseppe C. Pappalardo ◽  
Francesco Punzo ◽  
Ferdinando Costantino ◽  
Umberto Costantino ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Powder Diffraction ◽  
Layered Double Hydroxides ◽  
X Ray ◽  
Mixed Metal ◽  
Double Hydroxides

A Novel Integrated X-ray Powder Diffraction (XRPD) and Molecular Dynamics (MD) Approach for Modelling Mixed-Metal (Zn, Al) Layered Double Hydroxides (LDHs)

2005 ◽  
Vol 2005 (24) ◽  
pp. 5026-5034 ◽  
Author(s):  
Giuseppe M. Lombardo ◽  
Giuseppe C. Pappalardo ◽  
Francesco Punzo ◽  
Ferdinando Costantino ◽  
Umberto Costantino ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Powder Diffraction ◽  
Layered Double Hydroxides ◽  
X Ray ◽  
Mixed Metal ◽  
Double Hydroxides

Structural and microstructural changes during anion exchange of CoAl layered double hydroxides: anin situX-ray powder diffraction study

2010 ◽  
Vol 43 (3) ◽  
pp. 434-447 ◽  
Author(s):  
Rune E. Johnsen ◽  
Frank Krumeich ◽  
Poul Norby
Keyword(s):  
Phase Transformation ◽  
Exchange Reaction ◽  
Anion Exchange ◽  
Powder Diffraction ◽  
Layered Double Hydroxides ◽  
Two Phase ◽  
X Ray ◽  
Double Hydroxides ◽  
Anion Exchange Reaction

Anion-exchange processes in cobalt–aluminium layered double hydroxides (LDHs) were studied byin situsynchrotron X-ray powder diffraction (XRPD). The processes investigated were CoAl–CO3→ CoAl–Cl → CoAl–CO3, CoAl–Cl → CoAl–NO3and CoAl–CO3→ CoAl–SO4. The XRPD data show that the CoAl–CO3→ CoAl–Cl process is a two-phase transformation, where the amount of the CoAl–CO3phase decreases exponentially while that of the CoAl–Cl phase increases exponentially. Energy-dispersive X-ray spectroscopy (EDXS) studies of a partially chloride-exchanged CoAl–CO3LDH sample along within situXRPD data suggested that the individual particles in the CoAl–CO3sample are generally anion-exchanged with chloride one at a time. In contrast with the CoAl–CO3→ CoAl–Cl transformation, the XRPD data show that the reverse CoAl–Cl → CoAl–CO3process is a one-phase transformation. Rietveld refinements indicate that the occupancy factors of the carbon and oxygen sites of the carbonate group increase, while that of the chloride site decreases. In the CoAl–Cl → CoAl–NO3anion-exchange reaction, the XRPD patterns reveal the existence of two intermediate phases in addition to the initial CoAl–Cl and final CoAl–NO3phases. Thein situdata indicate that one of these intermediates is a mixed nitrate- and chloride-based LDH phase, where the disorder decreases as the nitrate content increases. The XRPD data of the partial CoAl–CO3→ CoAl–SO4anion-exchange reaction show that the process is a two-phase transformation involving a sulfate-containing LDH with a 1H polytype structure.

scholarly journals Synthesis and characterization of layered double hydroxides with different cations (Mg, Co, Ni, Al), decomposition and reformation of mixed metal oxides to layered structures

2011 ◽  
Vol 9 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Kristina Klemkaite ◽  
Igoris Prosycevas ◽  
Ricardas Taraskevicius ◽  
Alexander Khinsky ◽  
Aivaras Kareiva
Keyword(s):  
Metal Oxides ◽  
Layered Double Hydroxides ◽  
Xrd Analysis ◽  
Layered Structures ◽  
Magnesium Nitrate ◽  
Mixed Metal Oxides ◽  
X Ray ◽  
Mixed Metal ◽  
Different Temperatures ◽  
Double Hydroxides

AbstractThree layered double hydroxides (LDH) [Mg1−xAlx(OH)2]x+(Am−)x/m]·nH2O and [MII 1−xMIII x (OH)2]x+(Am−)x/m]·nH2O (MII — Mg, Co, Ni; MIII — Al; A — CO3 2−) were successfully synthesized by the low supersaturation method. The as-synthesized LDH samples were thermally decomposed and the derived mixed metal oxides reformed back to layered structures in water and magnesium nitrate media at different temperatures. All synthesized samples were characterized by X-ray diffraction (XRD) analysis, thermogravimetric (TG) analysis, X-ray fluorescence (XRF) analysis and scanning electron microscopy (SEM). The results of XRD and XRF analyses showed that single-phase layered double hydroxides were formed during synthesis and reformation. It was demonstrated, that a partially substituted by cobalt and nickel LDH samples also show memory effect. The crystallite size of regenerated LDH depends on the regeneration media, temperature and chemical composition. The LDH samples after regeneration consist of large particles with sharp edges along with a large amount of smaller particles

High-temperature X-ray powder diffraction as a tool for characterization of smectites, layered double hydroxides, and their intercalates with porphyrins

2010 ◽  
Vol 49 (4) ◽  
pp. 363-371 ◽  
Author(s):  
Anna Píšková ◽  
Petr Bezdička ◽  
David Hradil ◽  
Eva Káfuňková ◽  
Kamil Lang ◽  
...  
Keyword(s):  
High Temperature ◽  
Powder Diffraction ◽  
Layered Double Hydroxides ◽  
X Ray ◽  
Double Hydroxides

scholarly journals Synthesis of Mg-Fe layered double hydroxides and its application as catalyst for Friedel-Crafts benzoylation

2016 ◽  
Vol 19 (4) ◽  
pp. 185-193
Author(s):  
Phuong Thi Minh Nguyen ◽  
Phuong Hoang Tran ◽  
Chinh Quoc Nguyen
Keyword(s):  
Metal Oxides ◽  
Layered Double Hydroxides ◽  
Coprecipitation Method ◽  
Mixed Metal Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixed Metal ◽  
Before And After ◽  
Double Hydroxides

Mg-Fe layered double hydroxides were synthesized by the coprecipitation method with different of Mg/Fe ratio (2/1, 3/1 and 4/1) and then were thermally transformed into mixed metal oxides. The obtained materials before and after the calcination at 450 oC were characterized by X-ray diffraction (XRD), SEM, BET, TGA, ICP. The samples were used as a catalyst for Friedel-Crafts benzoylation reactions. The catalyst can be easily separated and recycled compared to the traditional one.

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