scholarly journals Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

2011 ◽  
Vol 76 (12) ◽  
pp. 1661-1671 ◽  
Author(s):  
Milica Hadnadjev-Kostic ◽  
Tatjana Vulic ◽  
Radmila Marinkovic-Neducin ◽  
Aleksandar Nikolic ◽  
Branislav Jovic
Keyword(s):  
Surface Properties ◽  
Layered Double Hydroxides ◽  
Active Sites ◽  
Mixed Oxides ◽  
Lower Surface ◽  
Multiphase System ◽  
Fischer Tropsch ◽  
Acid And Base ◽  
Phase Range ◽  
Double Hydroxides

The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH), with the general formula: [Mg1-xFex(OH)2](CO3)x/2?mH2O, x = = n(Fe)/(n(Mg)+n(Fe)), synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase), having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties.

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.

Influence of Ni/Al ratio on the fast pyrolysis of myristic acid when adsorbed on unsupported mixed oxides derived from layered double hydroxides

2020 ◽  
Author(s):  
Santiago Arias ◽  
Juan Felipe González ◽  
Lenivaldo V. Sousa ◽  
Celmy B.M. Barbosa ◽  
Antonio Osimar S. Silva ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Myristic Acid ◽  
Mixed Oxides ◽  
Fast Pyrolysis ◽  
Double Hydroxides

Structural Analysis of Defects in Layered Double Hydroxides and Related Mixed Oxides

2020 ◽  
Vol 90 (3) ◽  
pp. 509-522
Author(s):  
N. N. Leont’eva ◽  
V. А. Drozdov ◽  
О. B. Bel’skaya ◽  
S. V. Cherepanova
Keyword(s):  
Structural Analysis ◽  
Layered Double Hydroxides ◽  
Mixed Oxides ◽  
Double Hydroxides

Mixed oxides obtained from Co and Mn containing layered double hydroxides: Preparation, characterization, and catalytic properties

2006 ◽  
Vol 179 (3) ◽  
pp. 812-823 ◽  
Author(s):  
František Kovanda ◽  
Tomáš Rojka ◽  
Jana Dobešová ◽  
Vladimír Machovič ◽  
Petr Bezdička ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Double Hydroxides

scholarly journals Catalytic Combustion of Low Concentration Methane over Catalysts Prepared from Co/Mg-Mn Layered Double Hydroxides

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Hongfeng Liu ◽  
Xingrui Fu ◽  
Xiaole Weng ◽  
Yue Liu ◽  
Haiqiang Wang ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Layered Double Hydroxides ◽  
Catalytic Combustion ◽  
Mixed Oxides ◽  
Oxygen Mobility ◽  
Catalytic Combustion Of Methane ◽  
Redox Ability ◽  
Double Hydroxides ◽  
Mn Oxides

A series of Co/Mg-Mn mixed oxides were synthesized through thermal decomposition of layered double hydroxides (LDHs) precursors. The resulted catalysts were then subjected for catalytic combustion of methane. Experimental results revealed that the Co4.5Mg1.5Mn2LDO catalyst possessed the best performance with theT90=485°C. After being analyzed via XRD, BET-BJH, SEM, H2-TPR, and XPS techniques, it was observed that the addition of cobalt had significantly improved the redox ability of the catalysts whilst certain amount of magnesium was essential to guarantee the catalytic activity. The presence of Mg was helpful to enhance the oxygen mobility and, meanwhile, improved the dispersion of Co and Mn oxides, preventing the surface area loss after calcination.

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