Large continuous, transparent and oriented self-supporting films of layered double hydroxides with tunable chemical composition

2007 ◽  
pp. 123-125 ◽  
Author(s):  
Lianying Wang ◽  
Cang Li ◽  
Miao Liu ◽  
David G. Evans ◽  
Xue Duan
Keyword(s):  
Chemical Composition ◽  
Layered Double Hydroxides ◽  
Double Hydroxides

Application of Calcined Layered Double Hydroxides as Catalysts for Abatement of N2O Emissions

2008 ◽  
Vol 73 (8-9) ◽  
pp. 1045-1060 ◽  
Author(s):  
Lucie Obalová ◽  
František Kovanda ◽  
Květuše Jirátová ◽  
Kateřina Pacultová ◽  
Zdenek Lacný
Keyword(s):  
Chemical Composition ◽  
Layered Double Hydroxides ◽  
Mixed Oxide ◽  
Oxide Catalysts ◽  
Production Plant ◽  
Process Stream ◽  
Mixed Oxide Catalysts ◽  
General Chemical ◽  
Simulated Process ◽  
Double Hydroxides

The results of catalytic decomposition of N2O over mixed oxide catalysts obtained by calcination of layered double hydroxides (LDHs) are summarized. Mixed oxides were prepared by thermal treatment (500 °C) of coprecipitated LDH precursors with general chemical composition of MII1-xMIIIx(OH)2(CO3)x/2·yH2O, where MII was Ni, Co, Cu and/or Mg, MIII was Mn, Fe and/or Al, and the MII/MIII molar ratio was adjusted to 2. The influence of chemical composition of the MII-MIII mixed oxide catalysts on their activity and stability in N2O decomposition was examined. The highest N2O conversion was reached over Ni-Al (4:2) and Co-Mn-Al (4:1:1) catalysts. Their suitability for practical application was proved in simulated process stream in the presence of O2, NO, NO2 and H2O. It was found that N2O conversion decreased with increasing amount of oxygen in the feed. The presence of NO in the feed caused a slight decrease in N2O conversion. A strong decrease in the reaction rate was observed over the Ni-Al catalyst in the presence of NO2 while no N2O conversion decrease was observed over the Co-Mn-Al catalyst. Water vapor inhibited the N2O decomposition over all tested catalysts. The obtained kinetic data for N2O decomposition in a simulated process stream over the Co-Mn-Al catalyst were used for a preliminary reactor design. The packed bed volume necessary for N2O emission abatement in a HNO3 production plant was calculated as 35 m3 for waste gas flow rate of 30 000 m3 h-1.

scholarly journals Recent Progress on Transition Metal Based Layered Double Hydroxides Tailored for Oxygen Electrode Reactions

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1394
Author(s):  
Jing Wang ◽  
Heng Kong ◽  
Haihong Zhong ◽  
Yu Jiang ◽  
Fei Guo ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Transition Metal ◽  
Layered Double Hydroxides ◽  
Active Sites ◽  
Rational Design ◽  
Great Influence ◽  
Oxygen Electrode ◽  
Energy Storage And Conversion ◽  
Electrode Reactions ◽  
Double Hydroxides

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), namely, so-called oxygen electrode reactions, are two fundamental half-cell reactions in the energy storage and conversion devices, e.g., zinc–air batteries and fuel cells. However, the oxygen electrode reactions suffer from sluggish kinetics, large overpotential and complicated reaction paths, and thus require efficient and stable electrocatalysts. Transition-metal-based layered double hydroxides (LDHs) and their derivatives have displayed excellent catalytic performance, suggesting a major contribution to accelerate electrochemical reactions. The rational regulation of electronic structure, defects, and coordination environment of active sites via various functionalized strategies, including tuning the chemical composition, structural architecture, and topotactic transformation process of LDHs precursors, has a great influence on the resulting electrocatalytic behavior. In addition, an in-depth understanding of the structural performance and chemical-composition-performance relationships of LDHs-based electrocatalysts can promote further rational design and optimization of high-performance electrocatalysts. Finally, prospects for the design of efficient and stable LDHs-based materials, for mass-production and large-scale application in practice, are discussed.

scholarly journals Development of approaches to the formation of platinum centers with given properties using carriers with a layered structure

2019 ◽  
Vol 62 (1-2) ◽  
pp. 24-38
Author(s):  
O. Belskaya ◽  
V. Likholobov
Keyword(s):  
Chemical Composition ◽  
Layered Double Hydroxides ◽  
Layered Structure ◽  
Active Component ◽  
Interlayer Space ◽  
Supported Catalysts ◽  
Acid Base ◽  
Cationic Composition ◽  
Supported Platinum ◽  
Double Hydroxides

Specific properties of layered double hydroxides (LDH), directions of their use as supports and supports precursors for catalysts synthesis and the advantages of such catalysts in reactions of various types are considered. The ability to vary LDH the chemical composition (cationic layers, interlayer space) without destroying the structure of the material makes it possible to regulate its adsorption and acid-base properties, selectively realize various mechanisms for fixing the precursor of the active component to obtain highly disperse and stable supported catalysts. Approaches to the formation of particles of supported platinum with desired properties through changes in the anionic and cationic composition of LDH, using as an example the system Pt/MgAl(M)-LDH are proposed.

Interplay between Chemical Composition and Cation Ordering in the Magnetism of Ni/Fe Layered Double Hydroxides

2013 ◽  
Vol 52 (17) ◽  
pp. 10147-10157 ◽  
Author(s):  
Gonzalo Abellán ◽  
Eugenio Coronado ◽  
Carlos Martí-Gastaldo ◽  
Joao Waerenborgh ◽  
Antonio Ribera
Keyword(s):  
Chemical Composition ◽  
Layered Double Hydroxides ◽  
Cation Ordering ◽  
Double Hydroxides

Chemical composition and interlayer arrangement of polytype 3R2 Mg–Al layered double hydroxides

2011 ◽  
Vol 52 (4) ◽  
pp. 374-380 ◽  
Author(s):  
W.N. Budhysutanto ◽  
D. van Agterveld ◽  
E. Schomaker ◽  
B.D. Rossenaar ◽  
G.M. van Rosmalen ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Layered Double Hydroxides ◽  
Double Hydroxides

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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