scholarly journals Highly Reducible Nanostructured CeO2 for CO Oxidation

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 535 ◽  
Author(s):  
Gang Feng ◽  
Weining Han ◽  
Zhimiao Wang ◽  
Fang Li ◽  
Wei Xue
Keyword(s):  
Electron Microscope ◽  
Co Oxidation ◽  
Hydrothermal Process ◽  
Textural Properties ◽  
Space Velocity ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Co Conversion ◽  
Structure Morphology ◽  
Adsorption Desorption

Ceria in nanoscale with different morphologies, rod, tube and cube, were prepared through a hydrothermal process. The structure, morphology and textural properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and isothermal N2 adsorption-desorption. Ceria with different morphologies were evaluated as catalysts for CO oxidation. CeO2 nanorods showed superior activity to the others. When space velocity was 12,000 mL·gcat−1·h−1, the reaction temperature for 90% CO conversion (T90) was 228 °C. The main reason for the high activity was the existence of large amounts of easily reducible oxygen species, with a reduction temperature of 217 °C on the surface of CeO2 nanorods. Another cause was their relatively large surface area.

Synthesis and Characterization of Hierarchical ZSM-48 Zeolite

2012 ◽  
Vol 503-504 ◽  
pp. 756-759 ◽  
Author(s):  
Xiao Ling Liu ◽  
Xu Jin Wang ◽  
Yan Wang ◽  
Yan Jun Gong ◽  
Tao Dou
Keyword(s):  
Electron Microscope ◽  
Textural Properties ◽  
Total Surface Area ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Secondary Porosity ◽  
Transmission Electron ◽  
Angle Spinning ◽  
Adsorption Desorption

A series of hierarchical ZSM-48 zeolites was prepared by seed silanization. The structural and textural properties of the hierarchical ZSM-48 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR), and Fourier transform infrared spectroscopy adsorbed by pyridine (Py-IR). It was found that the crystal size of ZSM-48 was significantly reduced by seed silanization. Due to the secondary porosity in the mesopore region generated in hierarchical ZSM-48, both the total surface area and the pore volume of the material have a considerable increase. The enhancement of the textural properties could be controlled by changing the amount of silanizaiton agent.

scholarly journals Nanocrystalline ZrO2 and Pt-doped ZrO2 catalysts for low-temperature CO oxidation

2017 ◽  
Vol 8 ◽  
pp. 264-271 ◽  
Author(s):  
Amit Singhania ◽  
Shipra Mital Gupta
Keyword(s):  
Co Oxidation ◽  
Oxygen Vacancies ◽  
Space Velocity ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
Charge Imbalance ◽  
Transmission Electron ◽  
Co Conversion ◽  
Low Temperature Co Oxidation

Zirconia (ZrO2) nanoparticles were synthesized by solution combustion using urea as an organic fuel. Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), UV–vis and Fourier transform infrared (FTIR) measurements were performed in order to characterize the catalyst. The calculated crystallite size of ZrO2, calculated with the help of the Scherrer equation, was around 30.3 nm. The synthesized ZrO2 was scrutinized regarding its role as catalyst in the oxidation of carbon monoxide (CO). It showed 100% CO conversion at 240 °C, which is the highest conversion rate reported for ZrO2 in literature to date. It is found that through solution combustion, Pt2+ ions replace Zr4+ ions in the ZrO2 lattice and because of this, oxygen vacancies are formed due to charge imbalance and lattice distortion in ZrO2. 1% Pt was doped into ZrO2 and yielded excellent CO oxidation. The working temperature was lowered by 150 °C in comparison to pure ZrO2. Further, it is highly stable for the CO reaction (time-on-stream ≈ 40 h). This is because of a synergic effect between Pt and Zr components, which results in an increase of the oxygen mobility and oxygen vacancies and improves the activity and stability of the catalyst. The effects of gas hourly space velocity (GHSV) and initial CO concentration on the CO oxidation over Pt(1%)-ZrO2 were studied.

Ordered Mesoporous SBA-15 for Controlled Release of Water-Insolube Drug

2011 ◽  
Vol 236-238 ◽  
pp. 1873-1876 ◽  
Author(s):  
Jun Jie Tao ◽  
Yun Qiang Xu ◽  
Guo Wei Zhou ◽  
Cui Cui Wu ◽  
Hong Bin Song ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Controlled Release ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Mesoscopic Structure ◽  
Ordered Mesoporous ◽  
Adsorption Desorption ◽  
Phosphate Buffered Saline

Ordered mesoporous SBA-15 was synthesized through hydrothermal process under acidic condition. The material was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD), and N2 adsorption-desorption. The results indicated that SBA-15 has 2-dimensional hexagonal p6mm mesoscopic structure and well-ordered parallel mesochannel. The as-obtained mesoporous silica was used for controlled release of water-insolube drug emodin. The loading capacity could achieve 6.64 mg/g, and the release profiles that studied in phosphate buffered saline (PBS, pH = 7.4) showed that released amount of emodin was 95.8 % after 48 h.

A Facile Template Approach for Preparing Microstructures of Bimodal Crystalline Mesoporous Titania Powders

2012 ◽  
Vol 616-618 ◽  
pp. 1797-1800
Author(s):  
Yu Mei Gong ◽  
Qing Liang ◽  
Jing Chuan Song ◽  
Ling Ming Xia
Keyword(s):  
Electron Microscope ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Mesoporous Titania ◽  
Mass Ratio ◽  
X Ray Diffraction ◽  
Average Pore ◽  
X Ray ◽  
Transmission Electron ◽  
Adsorption Desorption

This paper presents the preparation of bimodal crystalline macro-/mesoporous titania powders by using a pluronic polymer (EO20PO70EO20, P123) as a template through a hydrothermal treatment. The as-prepared powders were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscope (SEM) and transmission electron microscope (TEM). The results reveal that the amount of P123 has a significant effect on the surface area of the mesoporous titania. When the mass ratio of P123:TBOT is 1:14, the crystalline macro-/mesoporous titania has the largest surface area (120.96 m2/g), the average pore diameter of this sample reaches a minimum of 6.67 nm.

scholarly journals Synthesis of BaTiO3 Nanoparticles via Hydrothermal Method

2017 ◽  
Vol 268 ◽  
pp. 172-176 ◽  
Author(s):  
Nurul Norfarina Hasbullah ◽  
Oon Jew Lee ◽  
Josephine Liew Ying Chyi ◽  
Soo Kien Chen ◽  
Zainal Abidin Talib
Keyword(s):  
Electron Microscope ◽  
Hydrothermal Method ◽  
Transmission Electron Microscope ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Average Size ◽  
Tga And Dsc

In this work, BaTiO3 nanoparticles were synthesized through hydrothermal method. The powder obtained from the hydrothermal process (as-synthesized powder) was calcined at 1000 °C. The phase formation and morphology of the as-synthesized and calcined powders were studied using X-ray diffraction (XRD), thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyzer, and transmission electron microscope (TEM). The XRD data showed that the as-synthesized powder is partially amorphous. Upon calcining the powder at 1000 °C, highly crystalline BaTiO3 with tetragonal structure was obtained. As shown by TGA and DSC analysis, the precursor powder was completely transformed into BaTiO3 at 1000 °C. The presence of BaCO3 as an impurity phase in the powder is due to the lack of Ba2+ / Ti3+/4+. Transmission electron microscope images showed that the particle size of the as-synthesized powder increased after calcination due to crystal growth. In addition, nanocubes with the average size of around 11.66 nm were obtained as a result of the calcination compared to the ellipsoid like particles of the as-synthesized powder.

THE ASSEMBLY OF CHAIN-LIKE Ni ARRAYS UNDER MAGNETIC FIELD AND ITS ENHANCED PROPERTIES

2010 ◽  
Vol 09 (05) ◽  
pp. 543-547 ◽  
Author(s):  
JUN WANG ◽  
SHIHE CAO ◽  
SIHUA XIA ◽  
NING GAN
Keyword(s):  
Magnetic Field ◽  
Electron Microscope ◽  
External Magnetic Field ◽  
Self Assembly ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Vertical Arrays ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Facile Hydrothermal Process

Chain-like nickel arrays assembled from magnetic Ni spheres were successfully prepared through a facile hydrothermal process at 200°C under a 0.25 T external magnetic field. The external magnetic field is strongly believed to be the driving force of the self-assembly. The sample was highly crystalline as confirmed by the X-ray diffraction (XRD) patterns. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images show that all Ni spheres are closely interconnected to form chains, with ~ 950 nm in diameter and ~ 1 cm in length, which arrange into vertical arrays on the silicon substrate. The coercivity and remnant magnetization ratio of the sample, 670 Oe and 0.612, respectively, are substantially higher than for the sample prepared without an applied external magnetic field (68 Oe and 0.336). Such enhancements can be attributed to their novel superstructure, shape anisotropy, reduced demagnetization factor, etc. This process can be used to fabricate large arrays of uniform chains of magnetic materials and modulate their magnetic properties.

Optical Properties of Water-Soluble Er-Doped ZnS Quantum Dots Synthesized by a Hydrothermal Process

2013 ◽  
Vol 800 ◽  
pp. 402-405 ◽  
Author(s):  
Gang Li ◽  
Li Hua Li ◽  
Liu Shuan Yang ◽  
Jin Liang Huang
Keyword(s):  
Quantum Dots ◽  
Average Particle Size ◽  
Hydrothermal Process ◽  
Water Soluble ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Er Doped

Er3+:ZnS quantum dots(QDs) were synthesized by hydrothermal process. The structure, morphology and luminescence properties were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. It was found that the Er3+:ZnS QDs are zinc blende structure with an average particle size of about 8 nm. In PL spectra, The broad peak of ZnS NCs located at 400nm was commonly assigned to sulfur vacancies. The intensity of exciting peak and emission peak at of Er3+:ZnS QDs decreased with doping concentration increasing.

scholarly journals MesoporousTiO2Micro-Nanometer Composite Structure: Synthesis, Optoelectric Properties, and Photocatalytic Selectivity

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Kun Liu ◽  
Lianjie Zhu ◽  
Tengfei Jiang ◽  
Youguang Sun ◽  
Hongbin Li ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Composite Structure ◽  
Mixed Solution ◽  
X Ray Diffraction ◽  
Sunlight Irradiation ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Synthesis ◽  
Ft Ir ◽  
Adsorption Desorption

Mesoporous anatase TiO2micro-nanometer composite structure was synthesized by solvothermal method at 180°C, followed by calcination at 400°C for 2 h. The as-prepared TiO2was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectrum (FT-IR). The specific surface area and pore size distribution were obtained from N2adsorption-desorption isotherm, and the optoelectric property of the mesoporous TiO2was studied by UV-Vis absorption spectrum and surface photovoltage spectra (SPS). The photocatalytic activity was evaluated by photodegradation of sole rhodamine B (RhB) and sole phenol aqueous solutions under simulated sunlight irradiation and compared with that of Degussa P-25 (P25) under the same conditions. The photodegradation preference of this mesoporous TiO2was also investigated for an RhB-phenol mixed solution. The results show that the TiO2composite structure consists of microspheres (∼0.5–2 μm in diameter) and irregular aggregates (several hundred nanometers) with rough surfaces and the average primary particle size is 10.2 nm. The photodegradation activities of this mesoporous TiO2on both RhB and phenol solutions are higher than those of P25. Moreover, this as-prepared TiO2exhibits photodegradation preference on RhB in the RhB-phenol mixture solution.

Synthesis of Flower-Like Mesoporous γ-AlOOH and γ-Al2O3 Nanoarchitectures via an Ionic Liquid-Assisted Hydrothermal Route

NANO ◽  
2019 ◽  
Vol 14 (04) ◽  
pp. 1950046
Author(s):  
Tong Il Kim ◽  
Hak Sung Yun ◽  
Yung Jon ◽  
Gwang Bok Han ◽  
Sung Il Chae ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ionic Liquid ◽  
Hydrothermal Reaction ◽  
Hydrothermal Process ◽  
Reaction System ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Transmission Electron ◽  
Adsorption Desorption

In this work, flower-like [Formula: see text]-AlOOH and [Formula: see text]-Al2O3 nanoarchitectures with excellent surface and mesoporous properties were successfully synthesized in ionic liquid-assisted hydrothermal reaction system. The as-prepared suprastructures were characterized by several techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption/desorption measurement. The formation mechanism of flower-like [Formula: see text]-AlOOH mesoporous crystallites by ionic liquid-assisted hydrothermal process was proposed and discussed. Flower-like [Formula: see text]-Al2O3 nanostructures were obtained by calcining the as-prepared [Formula: see text]-AlOOH at 600∘C for 2[Formula: see text]h, preserving the same morphology.

Influences of Reaction Temperature on Structure and Performances of SnO2 Nanocrystals Prepared by Microwave Hydrothermal Method

2014 ◽  
Vol 809-810 ◽  
pp. 122-127 ◽  
Author(s):  
Li Xiong Yin ◽  
Fei Fei Wang ◽  
Jian Feng Huang ◽  
Dan Wang ◽  
Jia Yin Li
Keyword(s):  
Electron Microscope ◽  
Reaction Temperature ◽  
Hydrothermal Reaction ◽  
Raw Materials ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Hydrothermal ◽  
Transmission Electron ◽  
Photocatalytic Activities

SnO2nanocrystals were synthesized using SnCl4•5H2O and NH3•H2O as the main raw materials and distilled water as the solvent by microwave hydrothermal. Reaction temperature on the structure and photocatalytic activities of the SnO2nanocrystals by microwave hydrothermal process was studied. The phase composition, morphologies and photocatalytic activities of the product were characterized by XRD (X-ray diffraction), SEM (scanning electron microscope), TEM (transmission electron microscope) and photochemical reaction instrument. Results show the crystalline and conglobation of the product have significant effect on its photocatalytic properties. The homogeneous low-agglomerated and well crystallined SnO2nanocrystals prepared at 180 °C has good photocatalytic activities during photocatalytic degradation of RhB process.

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