Effect of Al2O3 nano-particles on Ba(Zr0.95Ti0.05)O3 ceramics prepared by mixed oxide method

2021 ◽  
Vol 222 (1) ◽  
pp. 163-169
Author(s):  
Chompoonuch Warangkanagool ◽  
Theerachai Bongkarn
Keyword(s):  
Mixed Oxide ◽  
Nano Particles

scholarly journals Effect of the presence of CuOx on the catalytic behavior of bimetallic Au-Cu catalyst supported on Ce-Zr mixed oxide in CO preferential oxidation

2019 ◽  
Vol 39 (2) ◽  
Author(s):  
Juan David Arevalo ◽  
Julio César Vargas ◽  
Luis Fernando Córdoba
Keyword(s):  
Copper Oxide ◽  
Mixed Oxide ◽  
Bimetallic Catalyst ◽  
Mixed Oxides ◽  
Copper Catalyst ◽  
Gold Catalyst ◽  
Nano Particles ◽  
Preferential Oxidation ◽  
Catalytic Behavior ◽  
Catalytic Materials

The effect of the presence of copper was evaluated on a bimetallic catalyst Au-Cu based on mixed oxide cerium-zirconium in the preferential oxidation of CO (CO-PROX). Six catalytic materials, based on mixed oxides, were prepared: (1) the support (CeZr); (2) the monometallic catalysts, i.e. gold (Au/CeZr), (3) impregnated copper oxide (CuOx/CeZr) and (4) incorporated copper (CuCeZr); and the bimetallic catalysts, i.e. (5) impregnated copper oxide and gold (Au-CuOx/CeZr), and (6) gold and incorporated copper (Au/CuCeZr). The catalysts were evaluated in the CO-PROX in the range 30-300°C and atmospheric pressure, where the Au-CuOx/CeZr showed the best catalytic behavior. The influence of CO2 and H2O in the feed stream was evaluated on the catalytic performance of the Au-CuOx/CeZr. An inhibitory effect for the CO2 was observed, while the presence of H2O enhanced the performance. Additionally, the catalytic stability was evaluated, reaching CO conversion of 93% and selectivity of 90% for 118 h. The catalytic materials were characterized by XRD, showing in all cases the fluorite cubic structure. The N2 adsorption-desorption analyses showed that synthesized materials were mesoporous and the TPR-H2 test reveals that the presence of the active phase increases the reducibility of Ce4+ to Ce3+. Reduction peaks of the gold catalyst were present at lower temperatures than those of the copper catalyst, which is related to a hydrogen spillover phenomenon. Finally, the samples were analyzed by SEM and TEM, which confirmed the formation of nano-particles with a diameter of about 4 nm.

Glycerol steam reforming over La–Ce–Co mixed oxide-derived cobalt catalysts

RSC Advances ◽  
2015 ◽  
Vol 5 (56) ◽  
pp. 45184-45193 ◽  
Author(s):  
M. Surendar ◽  
T. V. Sagar ◽  
B. Hari Babu ◽  
N. Lingaiah ◽  
K. S. Rama Rao ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Mixed Oxide ◽  
Cobalt Catalysts ◽  
Nano Particles ◽  
Highly Active

Cobalt nano particles derived from the La–Ce–Co mixed oxide, after reduction, are highly active for glycerol steam reforming to produce hydrogen.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

Adsorption and reactivity of some sulphur-containing compounds on a mixed-oxide « cobalt molybdate » type catalyst

1975 ◽  
Vol 72 ◽  
pp. 1059-1064 ◽  
Author(s):  
David Dollimore ◽  
Andrew Galwey ◽  
Graham Rickety
Keyword(s):  
Mixed Oxide ◽  
Cobalt Molybdate

Polycaprolactone based membranes for the degradation of diclofenac present in water samples using ZnO nanoparticles as the active agent

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3153-3161
Author(s):  
Marco Antonio Juárez Sánchez ◽  
Miguel Ángel Meléndez Lira ◽  
Celestino Odín Rodríguez Nava
Keyword(s):  
Zno Nanoparticles ◽  
Wastewater Treatment Plants ◽  
Active Agent ◽  
Heterogeneous Photocatalysis ◽  
Nano Particles ◽  
Electrical Characteristics ◽  
Unit Operation ◽  
Fields Of Study ◽  
Drug Contamination ◽  
Positive Results

AbstractDrug contamination in water is one of the current fields of study. Since 1990, the presence of drugs in drinking water has been a concern to scientists and public. In Mexico, these organic compounds are not efficiently removed in wastewater treatment plants; therefore, alternative methodologies have been studied that allow these compounds to have a high percentage of degradation or be completely degraded. One example of these techniques is heterogeneous photocatalysis which has obtained positive results in the degradation of drugs using ZnO nanoparticles. These are commonly selected for their electrical characteristics, even though they disperse in water and an additional unit operation is required to separate them from the liquid medium. To eliminate drugs with nano particles in a single stage, polycaprolactone-based membranes with adhered ZnO nanoparticles, by means of electrospinning, were prepared to degrade drugs such as diclofenac. The technique used has shown to efficiently break down diclofenac in 4 hours according to the capillary electrophoresis readings.

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