The decomposition of the layered double hydroxides of Co and Al: Phase segregation of a new single phase spinel oxide

2015 ◽  
Vol 141 ◽  
pp. 80-87 ◽  
Author(s):  
Salem Babay ◽  
Alain Bulou ◽  
Anne Marie Mercier ◽  
Mouhamed Toumi
Keyword(s):  
Layered Double Hydroxides ◽  
Single Phase ◽  
Phase Segregation ◽  
Spinel Oxide ◽  
Phase Spinel ◽  
Double Hydroxides

scholarly journals A study of thermally activated Mg-Fe layered double hydroxides as potential environmental catalysts

2010 ◽  
Vol 75 (9) ◽  
pp. 1251-1257 ◽  
Author(s):  
Milica Hadnadjev-Kostic ◽  
Tatjana Vulic ◽  
Radmila Marinkovic-Neducin
Keyword(s):  
Layered Double Hydroxides ◽  
Active Sites ◽  
Single Phase ◽  
Mixed Oxides ◽  
Precipitation Method ◽  
Test Reaction ◽  
Thermally Activated ◽  
Fe Content ◽  
Multiphase Systems ◽  
Double Hydroxides

Layered double hydroxides (LDHs) and mixed oxides derived after thermal decomposition of LDH with different Mg-Fe content were investigated. These materials were chosen because of the possibility to tailor their various properties, such as ion-exchange capability, redox and acid-base properties and surface area. Layered double hydroxides, [Mg1-x Fex (OH)2](CO3)x/2 ? m H2O, (where x presents the content of trivalent ions, x = M(III)/[M(II) + M(III)]) were synthesized, using low supersaturation precipitation method. The influence of different Mg/Fe ratio on the structure and surface properties of LDH and derived mixed oxides was investigated in correlation to catalytic properties in chosen test reaction (Fischer-Tropsch synthesis). It was determined that the presence of active sites in the mixed oxides is influenced by structural properties of the initial LDH and by the presence of additional Fe phases. Furthermore, the synthesis outside the optimal range for the synthesis of single phase LDHs leads to the formation of metastable, multiphase systems with specific characteristics and active sites.

scholarly journals Investigation of Structural and Luminescent Properties of Sol-Gel-Derived Cr‑Substituted Mg3Al1−xCrx Layered Double Hydroxides

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1848
Author(s):  
Ligita Valeikiene ◽  
Inga Grigoraviciute-Puroniene ◽  
Arturas Katelnikovas ◽  
Aleksej Zarkov ◽  
Aivaras Kareiva
Keyword(s):  
Layered Double Hydroxides ◽  
Single Phase ◽  
Sol Gel ◽  
Visible Spectrum ◽  
Luminescent Properties ◽  
Ion Concentration ◽  
Substitution Level ◽  
Characteristic Emission ◽  
Chromium Substitution ◽  
Double Hydroxides

In the present work, Cr-substituted Mg3Al1−xCrx layered double hydroxides (LDHs) were synthesised through the phase conversion of sol-gel-derived mixed-metal oxides in an aqueous medium. The chromium substitution level in the range of 1 to 25 mol% was investigated. It was demonstrated that all synthesised specimens were single-phase LDHs. The results of elemental analysis confirmed that the suggested synthetic sol-gel chemistry approach is suitable for the preparation of LDHs with a highly controllable chemical composition. The surface microstructure of sol-gel-derived Mg3Al1−xCrx LDHs does not depend on the chromium substitution level. The formation of plate-like agglomerated particles, which consist of hexagonally shaped nanocrystallites varying in size from approximately 200 to 300 nm, was observed. Optical properties of the synthesised Mg3Al1−xCrx LDHs were investigated by means of photoluminescence. All Cr-containing powders exhibited characteristic emission in the red region of the visible spectrum. The strongest emission was observed for the sample doped with 5 mol% Cr3+ ions. However, the emission intensity of samples doped with 1–10 mol% Cr3+ ions was relatively similar. A further increase in the Cr3+ ion concentration to 25 mol% resulted in severe concentration quenching.

Acceptorless amine dehydrogenation and transamination using Pd-doped layered double hydroxides

2018 ◽  
Author(s):  
Diana Ainembabazi ◽  
Nan An ◽  
Jinesh Manayil ◽  
Kare Wilson ◽  
Adam Lee ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Oxidation States ◽  
Secondary Amines ◽  
Primary Amines ◽  
Acid Dissolution ◽  
Oxidative Amination ◽  
Strong Function ◽  
Excellent Activity ◽  
High Yields ◽  
Double Hydroxides

<div> <p>The synthesis, characterization, and activity of Pd-doped layered double hydroxides (Pd-LDHs) for for acceptorless amine dehydrogenation is reported. These multifunctional catalysts comprise Brønsted basic and Lewis acidic surface sites that stabilize Pd species in 0, 2+, and 4+ oxidation states. Pd speciation and corresponding cataytic performance is a strong function of metal loading. Excellent activity is observed for the oxidative transamination of primary amines and acceptorless dehydrogenation of secondary amines to secondary imines using a low Pd loading (0.5 mol%), without the need for oxidants. N-heterocycles, such as indoline, 1,2,3,4-tetrahydroquinoline, and piperidine, are dehydrogenated to the corresponding aromatics with high yields. The relative yields of secondary imines are proportional to the calculated free energy of reaction, while yields for oxidative amination correlate with the electrophilicity of primary imine intermediates. Reversible amine dehydrogenation and imine hydrogenation determine the relative imine:amine selectivity. Poisoning tests evidence that Pd-LDHs operate heterogeneously, with negligible metal leaching; catalysts can be regenerated by acid dissolution and re-precipitation.</p> </div> <br>

Antibiotic-anionic Clay Matrix Used for Drug Controlled Release

2018 ◽  
Vol 69 (2) ◽  
pp. 321-323
Author(s):  
Georgeta Zegan ◽  
Elena Mihaela Carausu ◽  
Loredana Golovcencu ◽  
Alina Sodor Botezatu ◽  
Eduard Radu Cernei ◽  
...  
Keyword(s):  
Controlled Release ◽  
Layered Double Hydroxides ◽  
Bioactive Molecules ◽  
Drug Controlled Release ◽  
Anionic Clays ◽  
Anionic Clay ◽  
Toxicological Studies ◽  
High Efficient ◽  
Clay Matrix ◽  
Double Hydroxides

Anionic clay matrix acting as drug controlled release system have shown in last years a great potential for delivery of bioactive molecules and chemical therapeutics. This organic-inorganic nanohybrid system is high efficient offering an excellent protection of intercalated compounds from degradation. Compared to other nanoparticles used in medical area, anionic clays type layered double hydroxides have found to be biocompatible according to toxicological studies. Ampicillin containing MgAlLDHs and ZnAlLDH samples have been prepared following two routes: anion-exchange procedure and reconstruction from calcined layered double hydroxides. Solid samples have been characterized by FTIR and SEM-EDX highlighting the alteration of pristine LDHs structure when the antibiotic is introduced in the interlayer gallery.

Nanohybrid Enzymes - Layered Double Hydroxides: Potential Applications

2006 ◽  
Vol 2 (3) ◽  
pp. 283-294 ◽  
Author(s):  
Claude Forano ◽  
Stephanie Vial ◽  
Christine Mousty
Keyword(s):  
Layered Double Hydroxides ◽  
Potential Applications ◽  
Double Hydroxides

Heterostructures of Ce-Ti/layered double hydroxides and the derived MMOs for photoenergy applications

2020 ◽  
Vol 513 ◽  
pp. 145853 ◽  
Author(s):  
Valentina Chivu ◽  
Diana Gilea ◽  
Nicoleta Cioatera ◽  
Gabriela Carja ◽  
Mihaela Mureseanu
Keyword(s):  
Layered Double Hydroxides ◽  
Double Hydroxides
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