Study of the Formation of WOx Nanostructures Supported on Zirconia Prepared by Different Synthesis Routes

2010 ◽  
Vol 1279 ◽  
Author(s):  
Martha L. Hernández ◽  
Ascención Montoya ◽  
Paz Del angel ◽  
Silvia P. Paredes ◽  
Sergio O. Flores
Keyword(s):  
Electron Microscopy ◽  
Active Sites ◽  
Synthesis Method ◽  
Isomerization Reaction ◽  
X Ray Diffraction ◽  
Tungstated Zirconia ◽  
X Ray ◽  
Preparation Route ◽  
Synthesis Routes ◽  
Scanning Electron

AbstractDifferent synthesis procedures of Pt supported on tungstated zirconia catalysts (Pt/WOx-ZrO2) were investigated with the aim to elucidate the different WOx nanostructures developed on the zirconia surface depending on the preparation route. Pt/WOx-ZrO2 catalysts were synthesized by the coprecipitation and impregnation methods and pretreated by various procedures such as different calcinations temperatures or the use of reflux. The catalysts characterization was carried out by X-ray diffraction (XRD), Raman spectroscopy, transmission and scanning electron microscopy (TEM, SEM) and nitrogen physisorption, and the catalytic activity was evaluated in the n-hexane isomerization reaction. The results indicate that the development of active sites for isomerization of n-hexane is enhanced by the stabilization of the WOx nanostructures on the surface of zirconia, before the formation of the WO3 crystallites, and it largely depends on the synthesis method.

scholarly journals Synthesis of Zeolite NaA from Low Grade (High Impurities) Indonesian Natural Zeolite

2014 ◽  
Vol 14 (2) ◽  
pp. 138-142 ◽  
Author(s):  
Asalil Mustain ◽  
Gede Wibawa ◽  
Mukhammad Furoiddun Nais ◽  
Miftakhul Falah
Keyword(s):  
Electron Microscopy ◽  
Natural Zeolite ◽  
Synthesis Method ◽  
Sem Analysis ◽  
Low Grade ◽  
Framework Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zeolite Naa ◽  
Scanning Electron

The zeolite NaA has been successfully synthesized from the low grade natural zeolite with high impurities. The synthesis method was started by mixing natural zeolite powder with NH4Cl aqueous solution in the reactor as pretreatment. The use of pretreatment was to reduce the impurities contents in the zeolite. The process was followed by alkaline fusion hydrothermal treatment to modify the framework structure of natural zeolite and reduce the SiO2/Al2O3 ratio. Finally, the synthesized zeolite was calcined at 600 °C for 2 h. The final zeolite product was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the morphology of the zeolite NaA was cubic shape as observed by SEM analysis and the synthesized zeolite NaA with pretreatment gave less impurity than without pretreatment.

scholarly journals Effects of different Sn contents on formation of Ti2SnC by self-propagating high-temperature synthesis method in Ti-Sn-C and Ti-Sn-C-TiC systems

2014 ◽  
Vol 32 (4) ◽  
pp. 696-701 ◽  
Author(s):  
Hong-Yan Sun ◽  
Xin Kong ◽  
Wei Sen ◽  
Zhong-Zhou Yi ◽  
Bao-Sen Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Raw Materials ◽  
Synthesis Method ◽  
Combustion Products ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Scanning Electron

AbstractEffect of different Sn contents on combustion synthesis of Ti2SnC was studied using elemental Ti, Sn, C and TiC powders as raw materials in the Ti-Sn-C and Ti-Sn-C-TiC system, in which the molar ratio of Ti/C was set as 2:1. The reaction mechanism for the formation of Ti2SnC was also investigated. The results showed that the amount of Ti2SnC in combustion products firstly increased with increasing of Sn content (0.6 to 0.8 mol), and then decreased with further increasing of Sn content (1.0 to 1.2 mol). Upon addition of 15 % TiC instead of Ti and C, the optimum addition of Sn decreased to 0.7 mol and a higher purity of Ti2SnC was obtained. The Ti2SnC powders were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Synthesis of Bi0.5Sb1.5Te3/Graphene Composite Powders

2013 ◽  
Vol 743-744 ◽  
pp. 83-87
Author(s):  
B.B. Liang ◽  
Y. Li ◽  
L.L. Xu ◽  
L.J. Wang ◽  
W. Jiang
Keyword(s):  
Electron Microscopy ◽  
Active Sites ◽  
Synthesis Method ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
X Ray ◽  
Graphene Composite ◽  
Transmission Electron ◽  
Different Content

In this paper, Bi0.5Sb1.5Te3/graphene composite powders were prepared by hydrothermal synthesis method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to characterize the morphology and structure of the composite powders. As a nanocomposite phase, graphene provided plenty of charge carriers and active sites for nucleation of Bi0.5Sb1.5Te3 grains. Bi0.5Sb1.5Te3 particles aggregated and attached to the surfaces of graphene randomly. In addition, it was found that the sizes of Bi0.5Sb1.5Te3 particles varied with different content of graphene. The formation mechanism of Bi0.5Sb1.5Te3/graphene composite powders was discussed.

scholarly journals Influence of Synthesis Method on LTA Time-Dependent Stability

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2122 ◽  
Author(s):  
Claudia Belviso ◽  
Antonio Lettino ◽  
Francesco Cavalcante
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Process ◽  
Synthesis Method ◽  
Synthetic Zeolite ◽  
Time Dependent ◽  
Time Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lta Zeolite ◽  
Scanning Electron

Time-stability of LTA zeolite formed by hydrothermal method with or without the action of ultrasonic irradiation was investigated by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The results show that 6 months after the synthesis by hydrothermal process with continuous sonication, LTA evolves into a more stable sodalite, whereas no differences are detected 12 months after LTA synthesis by conventional pre-fused hydrothermal process. These data confirm that using the two approaches, different mechanisms control both zeolite crystallization and time-stability of the newly-formed mineral at solid state. The results are particularly important in the light of the synthetic zeolite application.

scholarly journals Development of FeOOH nanoarrays using magnetic cations

2013 ◽  
Vol 11 (3) ◽  
pp. 358-363 ◽  
Author(s):  
Perla Garcia-Casillas ◽  
Carlos Martinez-Pérez ◽  
Claudia González ◽  
Héctor Camacho-Montes ◽  
Santos Martel Estrada ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
Cobalt Ions ◽  
X Ray ◽  
Average Size ◽  
20 Nm ◽  
Scanning Electron

AbstractAbstract In this work, FeOOH arrays were obtained using two different magnetic cations. The nanoparticles were grouped into a package having different orientations through the van der Waals interaction with the magnetic cations. With Fe2+, the FeOOH nanoparticles have a rod shape with a 30-nm diameter and approximately 1-micron length, and are aligned in a star structure. With Co2+, a somatoidal shape was observed, with 20-nm diameter and 150-nm length and a pathway structure to the array. The chemical synthesis method was used to obtain the nanoarrays. The morphology and the average size of the nanorods and nanowires were determined using Field Emission Scanning Electron Microscopy (FESEM). Fourier Transform Infrared Spectroscopy (FTIR) was used to study the interaction between the nanorods and the cobalt ions. The phases of the material were identified using X-ray Diffraction. Graphical abstract

Effect of Hydrogen Peroxide on TiB2-Based Materials

2009 ◽  
Vol 66 ◽  
pp. 222-225 ◽  
Author(s):  
Fei Huang ◽  
Zheng Yi Fu ◽  
Ai Hua Yan ◽  
Tie Kun Jia ◽  
Wei Min Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Peroxide ◽  
Synthesis Method ◽  
Anatase Tio2 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrothermal Approach ◽  
Final Composition ◽  
Scanning Electron

TiO2/TiB2 heterostructures were successfully synthesized by a facile hydrothermal approach in an aqueous solution of hydrogen peroxide (H2O2). The influence of H2O2 on TiB2-based materials was systematically investigated using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that TiB2 is prone to oxidize in the presence of H2O2. TiO2/TiB2 heterostructure which high-density anatase-TiO2 stand on the surface can be gained in the presence of H2O2 solvent and the final composition can be controlled by the temperature and time. The investigation may provide a path to further understand the chemical property of TiB2-based materials and synthesis method of heterostructure.

Different Pathways for Synthesis of WO3 and Vertically Aligned Carbon Nanotube-Based Nanostructures

2021 ◽  
Vol 21 (4) ◽  
pp. 2388-2393
Author(s):  
Anna Szabó ◽  
Gábor Kovács ◽  
Anita Kovács ◽  
Klara Hernadi
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotube ◽  
Vapor Deposition ◽  
Synthesis Method ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vertically Aligned ◽  
Carbon Nanotube Forests ◽  
Scanning Electron

The synthesis and investigation of vertically aligned carbon nanotube (VACNT) based materials are gaining more-and-more interest among scientists due to their specific properties (e.g., electrical, optical, mechanical). Therefore, our interest for the present research has focused on synthesis of WO3/VACNT based nanostructures (using carbon nanotube forests obtained by catalytic chemical vapor deposition—CCVD method on aluminum substrate) using different synthesis pathways and WO3 precursors. The obtained composites were investigated by scanning electron microscopy (SEM), Raman spectroscopy, while the obtained crystal structures were characterized by X-ray diffraction (XRD). Results have shown that depending on the synthesis method, and using as template the carbonaceous structure, we can successfully obtain non-stochiometric tungsten oxide (W18O49) or WO3 composites.

Effect of Synthesis Method on the Nanostructures of Magnesium Oxide (MgO) and their Band Gap Energies

2012 ◽  
Vol 545 ◽  
pp. 153-156 ◽  
Author(s):  
Nor Fadilah Chayed ◽  
Nurhanna Badar ◽  
Rusdi Roshidah ◽  
Norashikin Kamarudin ◽  
Norlida Kamarulzaman
Keyword(s):  
Electron Microscopy ◽  
Band Gap ◽  
Magnesium Oxide ◽  
Sol Gel ◽  
Synthesis Method ◽  
Nir Spectroscopy ◽  
Synthesis Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Magnesium oxide (MgO) is a metal oxide which has many applications in industry and can be synthesized by many different synthesis methods. In this study, MgO was synthesized by using two different methods which were sol-gel and solid-state reaction methods. Both samples were annealed at 800 oC for 24 hours and characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The band gap energies for both samples were determined by using UV-Vis NIR Spectroscopy. The band gap values of the samples are evaluated from the data. It was found that the band gap energies of the MgO using different synthesis route were not the same.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

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