Generation of Singlet Molecular Oxygen from H2O2 with Molybdate-Exchanged Layered Double Hydroxides: Effects of Catalyst Composition and Reaction Conditions

2001 ◽  
Vol 197 (1) ◽  
pp. 139-150 ◽  
Author(s):  
F.M.P.R van Laar ◽  
D.E De Vos ◽  
F Pierard ◽  
A Kirsch-De Mesmaeker ◽  
L Fiermans ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Layered Double Hydroxides ◽  
Reaction Conditions ◽  
Singlet Molecular Oxygen ◽  
Catalyst Composition ◽  
Double Hydroxides

Hydrotalcites as Catalysts and Catalysts Precursors for the Synthesis of Biodiesel

2013 ◽  
Vol 571 ◽  
pp. 1-26 ◽  
Author(s):  
Inés Reyero ◽  
Gurutze Arzamendi ◽  
Luis M. Gandía
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Vegetable Oils ◽  
Chemical Stability ◽  
Layered Double Hydroxides ◽  
Reaction Conditions ◽  
Basic Properties ◽  
Transesterification Catalysts ◽  
Double Hydroxides

This chapter aims at providing an overview of the potential of layered double hydroxides (LDHs) or hydrotalcite-like compounds (HTs) for contributing to the catalysis of the synthesis of biodiesel through the transesterification of triglycerides. First, the main methods of preparation of HTs and the most relevantfeatures of these materials are presented, with emphasis on their basic properties. Afterwards, the literature on the use of HTs as catalysts, catalysts precursors, and supports of transesterification catalysts is reviewed. HTs are promising materials for the synthesis of biodiesel from refined and waste vegetable oils, showing reasonable resistance to water and free fatty acids but an improvement of the chemical stability under the desired reaction conditions is still necessary.

scholarly journals Catalytic Synthesis of Methacrolein via the Condensation of Formaldehyde and Propionaldehyde with L-Proline Intercalated Layered Double Hydroxides

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 42
Author(s):  
Longxin Ju ◽  
Gang Li ◽  
Hongxian Luo
Keyword(s):  
Layered Double Hydroxides ◽  
Aldol Condensation ◽  
Condensation Reaction ◽  
Catalytic Performance ◽  
Operating Conditions ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Step Procedure ◽  
Aldol Condensation Reactions ◽  
Double Hydroxides

Aldol condensation reactions are very important C–C coupling reactions in organic chemistry. In this study, the catalytic performance of layered double hydroxides (LDHs) in the aldol condensation reaction of formaldehyde (FA) and propionaldehyde (PA) was investigated. The MxAl-LDHs (denoted as re-MxAl–LDHs; M = Ca and Mg; X = 2–4), as heterogeneous basic catalysts toward the aldol condensation reaction, were prepared via a two-step procedure. The catalyst exhibited a high PA conversion (82.59%), but the methacrolein (MAL) selectivity was only 36.01% due to the limitation of the alkali-catalyzed mechanism. On this basis, the direct intercalation of L-proline into LDHs also has been investigated. The influences of several operating conditions, including the temperature, reaction time, and substrate content, on the reaction results were systematically studied, and the optimized reaction conditions were obtained. The optimized Mg3Al–Pro-LDHs catalyst exhibited a much higher MAL selectivity than those of re-MgxAl–LDHs.

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.

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