Optimization of N2O decomposition activity of CuO–CeO2 mixed oxides by means of synthesis procedure and alkali (Cs) promotion

2018 ◽  
Vol 8 (9) ◽  
pp. 2312-2322 ◽  
Author(s):  
Maria Lykaki ◽  
Eleni Papista ◽  
Sónia A. C. Carabineiro ◽  
Pedro B. Tavares ◽  
Michalis Konsolakis
Keyword(s):  
Mixed Oxides ◽  
N2o Decomposition ◽  
Fine Tuning ◽  
Highly Active ◽  
Alkali Promotion ◽  
Synthesis Procedure ◽  
Co Precipitation

The fine-tuning of CuO–CeO2 mixed oxides by means of synthesis procedure (co-precipitation) and alkali promotion (1.0 at Cs per nm2) towards highly active deN2O catalysts is demonstrated.

scholarly journals Magnetofection: A Reproducible Method for Gene Delivery to Melanoma Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Lara Prosen ◽  
Sara Prijic ◽  
Branka Music ◽  
Jaka Lavrencak ◽  
Maja Cemazar ◽  
...  
Keyword(s):  
Gene Expression ◽  
Physicochemical Properties ◽  
Plasmid Dna ◽  
Water Solution ◽  
Superparamagnetic Iron Oxide ◽  
Synthesis Temperature ◽  
Fine Tuning ◽  
Synthesis Procedure ◽  
Sulfate Salts ◽  
Co Precipitation

Magnetofection is a nanoparticle-mediated approach for transfection of cells, tissues, and tumors. Specific interest is in using superparamagnetic iron oxide nanoparticles (SPIONs) as delivery system of therapeutic genes. Magnetofection has already been described in some proof-of-principle studies; however, fine tuning of the synthesis of SPIONs is necessary for its broader application. Physicochemical properties of SPIONs, synthesized by the co-precipitation in an alkaline aqueous medium, were tested after varying different parameters of the synthesis procedure. The storage time of iron(II) sulfate salt, the type of purified water, and the synthesis temperature did not affect physicochemical properties of SPIONs. Also, varying the parameters of the synthesis procedure did not influence magnetofection efficacy. However, for the pronounced gene expression encoded by plasmid DNA it was crucial to functionalize poly(acrylic) acid-stabilized SPIONs (SPIONs-PAA) with polyethyleneimine (PEI) without the adjustment of its elementary alkaline pH water solution to the physiological pH. In conclusion, the co-precipitation of iron(II) and iron(III) sulfate salts with subsequent PAA stabilization, PEI functionalization, and plasmid DNA binding is a robust method resulting in a reproducible and efficient magnetofection. To achieve high gene expression is important, however, the pH of PEI water solution for SPIONs-PAA functionalization, which should be in the alkaline range.

scholarly journals Facet-Dependent Reactivity of Ceria Nanoparticles Exemplified by CeO2-Based Transition Metal Catalysts: A Critical Review

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 452
Author(s):  
Michalis Konsolakis ◽  
Maria Lykaki
Keyword(s):  
Transition Metal ◽  
Co Oxidation ◽  
Critical Review ◽  
Rational Design ◽  
Metal Catalysts ◽  
Co2 Hydrogenation ◽  
Transition Metal Catalysts ◽  
Fine Tuning ◽  
Ceria Nanoparticles ◽  
Highly Active

The rational design and fabrication of highly-active and cost-efficient catalytic materials constitutes the main research pillar in catalysis field. In this context, the fine-tuning of size and shape at the nanometer scale can exert an intense impact not only on the inherent reactivity of catalyst’s counterparts but also on their interfacial interactions; it can also opening up new horizons for the development of highly active and robust materials. The present critical review, focusing mainly on our recent advances on the topic, aims to highlight the pivotal role of shape engineering in catalysis, exemplified by noble metal-free, CeO2-based transition metal catalysts (TMs/CeO2). The underlying mechanism of facet-dependent reactivity is initially discussed. The main implications of ceria nanoparticles’ shape engineering (rods, cubes, and polyhedra) in catalysis are next discussed, on the ground of some of the most pertinent heterogeneous reactions, such as CO2 hydrogenation, CO oxidation, and N2O decomposition. It is clearly revealed that shape functionalization can remarkably affect the intrinsic features and in turn the reactivity of ceria nanoparticles. More importantly, by combining ceria nanoparticles (CeO2 NPs) of specific architecture with various transition metals (e.g., Cu, Fe, Co, and Ni) remarkably active multifunctional composites can be obtained due mainly to the synergistic metalceria interactions. From the practical point of view, novel catalyst formulations with similar or even superior reactivity to that of noble metals can be obtained by co-adjusting the shape and composition of mixed oxides, such as Cu/ceria nanorods for CO oxidation and Ni/ceria nanorods for CO2 hydrogenation. The conclusions derived could provide the design principles of earth-abundant metal oxide catalysts for various real-life environmental and energy applications.

Synergy of FexCe1−xO2 mixed oxides for N2O decomposition

2006 ◽  
Vol 239 (2) ◽  
pp. 340-346 ◽  
Author(s):  
F PEREZALONSO ◽  
I MELIANCABRERA ◽  
M LOPEZGRANADOS ◽  
F KAPTEIJN ◽  
J FIERRO
Keyword(s):  
Mixed Oxides ◽  
N2o Decomposition

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

scholarly journals Copper-Containing Mixed Metal Oxides (Al, Fe, Mn) for Application in Three-Way Catalysis

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1344
Author(s):  
Tim Van Everbroeck ◽  
Radu-George Ciocarlan ◽  
Wouter Van Hoey ◽  
Myrjam Mertens ◽  
Pegie Cool
Keyword(s):  
Catalytic Activity ◽  
Spinel Structure ◽  
Mixed Oxides ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Application ◽  
Mixed Spinel ◽  
Co Precipitation ◽  
Three Way Catalysis

Mixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 °C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 °C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 °C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O2. All the materials calcined at 600 °C displayed the remarkable ability to oxidize CO with O2 but also to reduce NO with CO, while the pure oxides such as CuO and MnO2 were not able to. The high catalytic activity at 600 °C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 °C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl2O4 and CuFe2O4 still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H2-Temperatrue Programmed Reduction (H2-TPR), N2-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).

Transformation of Methane into Synthesis Gas Using the Redox Property of Pr-Zr Mixed Oxides: Effect of Calcination Temperature

2013 ◽  
Vol 724-725 ◽  
pp. 1187-1191
Author(s):  
Yong Gang Wei ◽  
Yun Peng Du ◽  
Kong Zhai Li ◽  
Xing Zhu ◽  
Hua Wang
Keyword(s):  
Calcination Temperature ◽  
Synthesis Gas ◽  
Mixed Oxides ◽  
Structural Evolution ◽  
Temperature Stability ◽  
Phase Segregation ◽  
Oxygen Carriers ◽  
High Temperature Stability ◽  
Calcination Temperatures ◽  
Co Precipitation

Pr-Zr mixed oxides prepared by co-precipitation were used as oxygen carriers for converting methane into synthesis gas through gas-solid reactions. The structural evolution and reducibility of Pr-Zr oxygen carriers with calcination temperatures from 600 to 1200°C were investigated by XRD and TPR techniques and correlated to their activity for methane selective oxidation. The Pr-Zr mixed oxides calcined at 600-800°C show outstanding thermostability, and higher calcination temperatures result in phase segregation. Pr0.7Zr0.3O2-δ possesses high temperature stability(<900 °C) and the best appropriate calcination temperature is 800°C for methane gas-solid reaction.

MgLa mixed oxides as highly active and selective heterogeneous catalysts for Wadsworth–Emmons reactions

2005 ◽  
Vol 55 (3) ◽  
pp. 177-183 ◽  
Author(s):  
M.L. Kantam ◽  
H. Kochkar ◽  
J.-M. Clacens ◽  
B. Veldurthy ◽  
A. Garcia-Ruiz ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Mixed Oxides ◽  
Highly Active

Microemulsion solventing-out co-precipitation strategy for fabricating highly active Cu–ZnO/Al2O3 dual site catalysts for reverse water gas shift

2020 ◽  
Vol 10 (8) ◽  
pp. 2343-2352
Author(s):  
Ziheng Zhen ◽  
Wenxiang Tang ◽  
Wei (Willy) Chu ◽  
Tao Zhang ◽  
Li Lv ◽  
...  
Keyword(s):  
Solvent Extraction ◽  
Water Gas Shift ◽  
Extraction Technology ◽  
Highly Active ◽  
Reverse Water Gas Shift ◽  
New Strategy ◽  
Co Precipitation ◽  
Water Gas ◽  
Dual Site

A new strategy for the preparation of dual site catalysts is introduced, which combines microemulsion technology and anti-solvent extraction technology.

scholarly journals Effects of hydrogen peroxide co-precipitation and inert N2 atmosphere calcination on CeZrLaNd mixed oxides and the catalytic performance used on Pd supported three-way catalysts

RSC Advances ◽  
2019 ◽  
Vol 9 (14) ◽  
pp. 8081-8090 ◽  
Author(s):  
Meisheng Cui ◽  
Yongke Hou ◽  
Zhizhe Zhai ◽  
Qiang Zhong ◽  
Yongqi Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Particle Size ◽  
Mixed Oxides ◽  
Catalytic Performance ◽  
Peroxide Oxidation ◽  
N2 Atmosphere ◽  
Hydrogen Peroxide Oxidation ◽  
Co Precipitation

Hydrogen peroxide oxidation improves the grains growth. Inert N2 atmosphere calcination reduces the particle size and enlarges the pore channels.

Phase analysis in the Fe2O3NiO mixed oxides prepared by co-precipitation

1984 ◽  
Vol 53 (2) ◽  
pp. 227-235 ◽  
Author(s):  
S. Rajendran ◽  
V.Sitakara Rao ◽  
H.S. Maiti
Keyword(s):  
Phase Analysis ◽  
Mixed Oxides ◽  
Co Precipitation
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