Combustion Synthesis of Nanoscale Oxide Powders: Mechanism, Characterization and Properties

2003 ◽  
Vol 800 ◽  
Author(s):  
Arvind Varma ◽  
Alexander S. Mukasyan ◽  
Kishori T. Deshpande ◽  
Pavol Pranda ◽  
Peter R. Erri
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Thermal Conditions ◽  
Optimum Conditions ◽  
Combustion Mode ◽  
Chemical Mechanisms ◽  
Oxide Powders ◽  
Extensive Experimental Data ◽  
First Time ◽  
Detailed Chemical

ABSTRACTBased on the analysis of extensive experimental data, we have formulated basic criteria necessary for the synthesis of a variety of oxides in the combustion mode, and defined optimum conditions for the production of high-surface area, well-crystalline nano-powders of desired phase composition and purity. Also, for the first time, detailed chemical mechanisms of interaction for various systems are identified, outlining specific roles of different fuels, oxidizers and thermal conditions

scholarly journals Silica-Coated Metal Oxide Powders with High Surface Area.

2002 ◽  
Vol 110 (1288) ◽  
pp. 1097-1099 ◽  
Author(s):  
Daiji SHIN ◽  
Satoshi SATO ◽  
Ryoji TAKAHASHI ◽  
Toshiaki SODESAWA
Keyword(s):  
Metal Oxide ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Oxide Powders ◽  
Coated Metal

scholarly journals Melt Infiltration Processing of Foams Using Glass-Forming Alloys

2002 ◽  
Vol 754 ◽  
Author(s):  
C. San Marchi ◽  
A. Brothers ◽  
D. C. Dunand
Keyword(s):  
Thermal Conductivity ◽  
Metallic Glass ◽  
Relative Density ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Glass Forming ◽  
Melt Infiltration ◽  
First Time ◽  
Infiltration Techniques

ABSTRACTProcessing of foams from bulk metallic glass (BMG) alloys, using melt infiltration techniques, is reported for the first time. Foaming methods based on infiltration of two types of pattern materials are described: investment of a continuous refractory yielding very low relative density structures (5% dense relative to the BMG), and investment of a discontinuous refractory pellet bed yielding higher relative density (50–60% dense relative to the BMG). Both methods are capable of producing foam structures; however high surface area and diminished thermal conductivity, especially in lower density structures, make vitrification of the alloy difficult.

scholarly journals Iron removal from ground water using Egyptian cost-effective clay minerals

2020 ◽  
Vol 3 (1) ◽  
pp. 23
Author(s):  
Hamdy Maamoun Abdel-Ghafar ◽  
ElSayed Abdel-Aal ◽  
Bahgat El_anadouli
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Chemical Characterization ◽  
Statistical Design ◽  
Cost Effective ◽  
Iron Removal ◽  
Optimum Conditions ◽  
Physical And Chemical Characterization ◽  
Physical And Chemical

Glauconite and kaolin are used as adsorbent materials for iron removal from synthetic solutions. Different concentrations of iron solutions have been prepared (10, 20 and 30 mg/L). Different dose of glauconite and kaolin were added (0.1, 0.55 and 1.0 g). Statistical design was used to determine the optimum conditions of iron adsorption on glauconite and kaolin. It is shown that glauconite has high adsorption for iron reaching to 95% while kaolin has lower adsorption for iron. Physical and chemical characterization of glauconite and kaolin was tested. High surface area of glauconite (19.8 m2/g) compared to kaolin (5.4 m2/g) explains its high removal efficiency. 

scholarly journals Methanation of CO2 over Cobalt-Lanthanide Aerogels: Effect of Calcination Temperature

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 704 ◽  
Author(s):  
Joaquim Badalo Branco ◽  
Ricardo Pinto da Silva ◽  
Ana Cristina Ferreira
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Oxide Phase ◽  
Addition Method ◽  
Acid Base ◽  
Lanthanide Oxide ◽  
Lanthanide Series ◽  
Rh Catalyst ◽  
Different Temperatures ◽  
First Time

High surface area cobalt-lanthanide bimetallic aerogels were successfully synthesized by the epoxide addition method. The bimetallic aerogels were calcined at two different temperatures and either bimetallic oxides containing oxychlorides, Co3O4.3LnOCl (Ln = La, Sm, Gd, Dy and Yb) or perovskites, LnCoO3 (Ln = La, Sm, Gd and Dy) were obtained at 500 or 900 °C, respectively. The exceptions are the aerogels of cerium and ytterbium, which after oxidation at 500 and 900 °C, stabilize as sesquioxides: Co3O4.3CeO2 and 2Co3O4.3Yb2O3, the first at both temperatures and the second only at the highest temperature. The bimetallic cobalt-lanthanide oxychlorides or perovskites were tested as catalysts for the methanation of CO2. The cobalt catalytic activity is determined by the type and acid-base properties of the lanthanide oxide phase and by its pre-reduction under hydrogen. The best results were those obtained over the calcined aerogels pre-reduced under hydrogen. In particular, the highest values were those obtained over the Co-Ce aerogel calcined at 900 °C that in the same conditions present an activity comparable to that measured over a 5 wt.% Rh catalyst supported on alumina, one of the literature references. The activity and the selectivity increase with the catalysts’ basicity, showing an inverse dependence of the reduction temperature that decreases along the lanthanide series either for the aerogels calcined at 500 or 900 °C. In general, the basicity of the aerogels calcined at 900 °C (perovskites) is higher and they are more active but less selective than those calcined at 500 °C (oxychlorides), which to our knowledge is for the first time reported for the methanation of CO2.

Formation of mixed oxide powders in flames: Part I. TiO2−SiO2

1992 ◽  
Vol 7 (7) ◽  
pp. 1861-1869 ◽  
Author(s):  
Cheng-Hung Hung ◽  
Joseph L. Katz
Keyword(s):  
Light Scattering ◽  
Optical Fibers ◽  
Mixed Oxide ◽  
Active Sites ◽  
High Surface ◽  
High Surface Area ◽  
Particle Morphology ◽  
Effect Of Temperature ◽  
Strong Temperature Dependence ◽  
Oxide Powders

Mixed oxide powders, e.g., Al2O3−TiO2, SiO2−GeO2, and TiO2−SiO2, are used in industry to produce ceramics, optical fibers, catalysts, and paint opacifiers. The properties of these products depend upon the morphology of the powders. Ceramics and optical fibers are produced using either a uniform mixture of multicomponent particles or a uniform solution. The desired morphology for catalysts is a high surface area and many active sites. TiO2 coated with a layer of SiO2 is the desired structure for use as a paint opacifier. In this paper, TiO2−SiO2 mixed oxide powders were synthesized using a counterflow diffusion flame burner. TiCl4 and SiCl4 were used as source materials for the formation of oxide particles in hydrogen-oxygen flames. In situ particle sizes were determined using dynamic light scattering. A thermophoretic sampling method also was used to collect particles directly onto carbon coated grids, and their size, morphology, and crystalline form examined using a transmission electron microscope. A photomultiplier at 90° to the argon ion laser beam was used to measure the light-scattering intensity. The effect of temperature and of Si to Ti concentration ratio on particle morphology was investigated. Strong temperature dependence was observed. At high temperatures, TiO2 particles were covered with discrete SiO2 particles. At low temperatures, the structure changes to TiO2 particles encapsulated by SiO2. TEM diffraction pattern measurements showed that the TiO2 is rutile and the SiO2 is amorphous silica. At high Si to Ti ratios, SiO2-encapsulated TiO2 particles form. At low Si to Ti ratios, one obtains TiO2 particles covered with discrete SiO2 particles.

THERMAL PROCESSING OF BUNDLED TUNGSTEN OXIDE NANOWIRES

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1541-1547 ◽  
Author(s):  
SHIBIN SUN ◽  
YIMIN ZHAO ◽  
YONGDE XIA ◽  
ZENGDA ZOU ◽  
GUANGHUI MIN ◽  
...  
Keyword(s):  
Tungsten Oxide ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Wide Band ◽  
Temperature Limit ◽  
Wide Band Gap ◽  
Significant Drop ◽  
Oxide Nanowires ◽  
First Time

Taking the wide band gap one-dimensional (1-D) tungsten oxide nanowires as an example, we here demonstrate systematically the physical characteristics of thermally processed nanowires at temperatures ranging from 400°C to 1000°C, for the first time. Accompanied by a significant drop of specific surface area from 151 m2/g for the as-prepared nanowires to 109 m2/g and 66 m2/g subject to annealing at 400°C and 450°C, dramatically morphology evolution and phase transformation have also been observed. The nanostructured bundles became straighter, larger in diameters and shorter in length, and eventually became irregular particles with size up to 5 µm. The Brunauer-Emmett-Tettler (BET) result suggests that 400°C can be considered as a top temperature limit in nanodevice design where high surface area is important, e.g. in gas sensors. A protocol for thermally processing of these bundled tungsten nanowires has been established.

Unique perforated graphene derived from Bougainvillea flowers for high-power supercapacitors: a green approach

Nanoscale ◽  
2017 ◽  
Vol 9 (14) ◽  
pp. 4801-4809 ◽  
Author(s):  
Rajendra P. Panmand ◽  
Purnima Patil ◽  
Yogesh Sethi ◽  
Sunil R. Kadam ◽  
Milind V. Kulkarni ◽  
...  
Keyword(s):  
Surface Area ◽  
High Power ◽  
High Surface ◽  
High Surface Area ◽  
Single Step ◽  
Step Method ◽  
Green Approach ◽  
Template Free ◽  
First Time

Herein, we demonstrated a green approach for the synthesis of high surface area (850 m2 g−1) mesoporous perforated graphene (PG) from Bougainvillea flower for the first time using a template free single-step method.

Research progress on individual effect of graphene oxide in cement-based materials and its synergistic effect with other nanomaterials

2021 ◽  
Vol 10 (1) ◽  
pp. 1208-1235
Author(s):  
Changjiang Liu ◽  
Fulian Chen ◽  
Yuyou Wu ◽  
Zhoulian Zheng ◽  
Jingwei Yang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Synergistic Effects ◽  
High Surface ◽  
High Surface Area ◽  
Research Progress ◽  
Surprising Effect ◽  
Cement Based Materials ◽  
Nanohybrid Materials ◽  
New Research ◽  
First Time

Abstract Poor crack resistance, high brittleness, and poor toughness are inherent limitations of traditional cement-based materials. Besides, cement-based materials have certain shortcomings in energy consumption and environmental protection. Therefore, improving the performance of cement-based materials becomes a hot topic in related research. At the same time, the development of nanomaterials and technologies provides researchers with a new research idea: to enhance the performance of cement-based materials at the nanoscale level. Graphene oxide (GO) is one of the most representative nano-reinforcements. Due to its high surface area and excellent physical properties, GO has a surprising effect on improving the performance of cement-based materials. In addition, nanosilica (NS) and carbon nanotubes (CNTs) have excellent improvement on cement-based materials, and people also hope to further improve the performance of cement-based materials through the interaction of various nanomaterials. In this paper, the influence of GO on cement-based materials is reviewed by consulting a lot of correlative literature, mainly focusing on the following aspects: (i) The dispersion of GO in cement paste. (ii) The influence of GO on the properties of cement-based materials, including working performance, mechanical strength, microstructural characteristics, and durability. (iii) The effect of nanohybrid materials of GO, NS, and CNTs on cement-based materials, and the synergistic effects of various nanomaterials are reviewed for the first time. (iv) Evaluation of current progress. This paper aims to provide guidance for the study and application of GO-modified cement-based materials and nanohybrid materials.

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