scholarly journals Flame-made Ceria Nanoparticles

2002 ◽  
Vol 17 (6) ◽  
pp. 1356-1362 ◽  
Author(s):  
L. Mädler ◽  
W. J. Stark ◽  
S. E. Pratsinis
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Acetic Acid Solution ◽  
High Surface Area ◽  
Flame Spray ◽  
Good Thermal Stability ◽  
Primary Particles ◽  
Stepped Surface

Flame spray pyrolysis (FSP) has been used to synthesize high-surface-area ceria from cerium acetate in acetic acid solution. With the addition of an iso-octane/2-butanol mixture to that solution, homogeneous CeO2 nanoparticles were obtained. The specific surface area of the powders ranged from 240 to 101 m2/g by controlling the oxygen dispersion and liquid precursor flow rates through the flame. Furthermore, for production rates from 2 to 10 g/h a constant average primary particle size could be obtained at selected process parameters. The ceria showed high crystallinity and primary particles with a stepped surface. The powder exhibited good thermal stability and conserved up to 40% of its initial specific surface area when calcinated for 2 h at 900 °C. This shows the potential of FSP made ceria for high-temperature applications as in three-way catalysts or fuel cells.

scholarly journals Synthesis of Nanostructured TiO2 Microparticles with High Surface Area

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1512
Author(s):  
Lev Matoh ◽  
Boštjan Žener ◽  
Tina Skalar ◽  
Urška Lavrenčič Štangar
Keyword(s):  
Particle Size ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Tio2 Particle ◽  
Nanostructured Tio2 ◽  
Degradation Rates

Hydrothermal reactions represent a simple and efficient method for the preparation of nanostructured TiO2 particles that could be of interest as photocatalysts or catalytic supports. Although the particle size is in the range of 2–5 µm, the nanostructures composing the particles ensure a large specific surface area with values above 100 m2/g. The effects of the different synthesis parameters on the morphology, photocatalytic activity, and stability of the prepared material were studied. The surface morphology of the prepared TiO2 powders was studied by scanning electron microscopy (SEM). To further characterize the samples, the specific surface area for different morphologies was measured and the photocatalytic activity of the prepared powders was tested by degrading model pollutants under UV irradiation. The results show that the initial morphology had little effect on the photocatalytic properties. On the other hand, the final calcination temperature significantly increased the degradation rates, making it comparable to that of P25 TiO2 (particle size 20–30 nm).

Effect of Solvothermal Treatment on Physical Properties of Nickel and Aluminum Based Oxide Powders Synthesized by Coprecipitation

2015 ◽  
Vol 820 ◽  
pp. 73-78
Author(s):  
Guilherme Luis Cordeiro ◽  
Walter Kenji Yoshito ◽  
Valter Ussui ◽  
Nelson Batista de Lima ◽  
Dolores Ribeiro Ricci Lazar
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Nickel Content ◽  
High Surface Area ◽  
Aging Treatment ◽  
Catalytic Efficiency ◽  
Nickel Aluminate ◽  
Solvothermal Treatment

Improvements of the catalytic efficiency of nickel–aluminum oxides in reforming reactions for hydrogen production have been achieved by the development of synthesis processes that provide powders with high surface area. The reduction of the crystallization temperature is one of the procedures in this direction. In this work, the effect of solvothermal treatment on coprecipitated gels with 15 wt% nickel content in alumina matrix was evaluated. Powders were obtained by coprecipitation with and without treatment of gels under n-butanol vapor pressure at 150oC. Products were characterized by TG/DTA, X-ray diffraction, specific surface area measurements, scanning electron microscopy and laser beam scattering for granulometric distribution determination. The results showed that calcined powders have high specific surface area (ranging from 170 to 260 m2.g-1) and are composed by gamma alumina and nickel aluminate phases. Aging treatment did not promote hydroxides decomposition under solvothermal conditions, indicating the need of calcination step.

Ion-matching porous carbons with ultra-high surface area and superior energy storage performance for supercapacitors

2019 ◽  
Vol 7 (15) ◽  
pp. 9163-9172 ◽  
Author(s):  
Lifeng Zhang ◽  
Yu Guo ◽  
Kechao Shen ◽  
Jinghao Huo ◽  
Yi Liu ◽  
...  
Keyword(s):  
Energy Storage ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
High Specific Surface Area ◽  
Porous Carbons ◽  
Storage Performance

Polypyrrole (PPy)-derived porous carbons with an ion-matching micropore diameter exhibit ultra-high specific surface area and capacitance when used in supercapacitors.

Effect of phase composition, morphology, and specific surface area on the photocatalytic activity of TiO2 nanomaterials

RSC Advances ◽  
2014 ◽  
Vol 4 (87) ◽  
pp. 47031-47038 ◽  
Author(s):  
Hao Cheng ◽  
Jingyu Wang ◽  
Yizhi Zhao ◽  
Xijiang Han
Keyword(s):  
Photocatalytic Activity ◽  
Phase Composition ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Tio2 Nanomaterials

TiO2-based nanomaterials could reach the maximal photoactivity when designing 0D/1D heterogenous structure with appropriate phase composition and high surface area.

scholarly journals WO3Nanoplates Film: Formation and Photocatalytic Oxidation Studies

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Oxidation Reaction ◽  
Photocatalytic Oxidation ◽  
Dye Degradation ◽  
Film Formation ◽  
High Surface ◽  
High Surface Area ◽  
Electrochemical Anodization

High surface area of tungsten oxide (WO3) nanoplates films was prepared via simple electrochemical anodization technique by controlling the fluoride content (NH4F) in electrolyte. The design and development of WO3-based nanostructure assemblies have gained significant interest in order to maximize specific surface area for harvesting more photons to trigger photocatalytic oxidation reaction. This study aims to determine the optimum content of NH4F in forming WO3nanoplates on W film with efficient photocatalytic oxidation reaction for organic dye degradation by utilizing our solar energy. The NH4F was found to influence the chemical dissolution and field-assisted dissolution rates, thus modifying the final morphological of WO3-based nanostructure assemblies film. It was found that 0.7 wt% of NH4F is the minimum amount to grow WO3nanoplates film on W film. The photocatalysis oxidation experimental results showed that WO3nanoplates film exhibited a maximum degradation of methyl orange dye (≈75%) under solar illumination for 5 hours. This behavior was attributed to the better charge carriers transportation and minimizes the recombination losses with specific surface area of nanoplates structure.

Metal Oxides (such as Al2O3 and TiO2) as Catalyst Supports for Hydrogen Release by Hydrolysis of Sodium Borohydride NaBH4

2010 ◽  
Vol 65 ◽  
pp. 209-214
Author(s):  
Ouardia Akdim ◽  
Umit Bilge Demirci ◽  
Philippe Miele
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Active Phase ◽  
Hydrogen Release ◽  
Catalytic Systems ◽  
Hydrolysis Of

Hydrolysis of NaBH4 to release molecular hydrogen is today an intensely investigated reaction and most of the studies focus on the material used as catalyst. Among the various metals tested up to now, cobalt has soon showed to be the most attractive in terms of reactivity and cost. Nevertheless, in order to further decrease its cost by decreasing its amount as well as to increase its reactivity, cobalt has been dispersed over supports. The as-formed supported catalysts have showed to be more efficient. This is the topic of the present study. Herein it is showed that CoCl2 supported over an Al2O3 support with a specific surface area of 180 m2 g-1 is more reactive than CoCl2 supported over a high-surface-area activated carbon (780 m2 g-1), CoCl2 being in-situ reduced into the Co-based active phase. CoCl2-Al2O3 is besides as reactive as another CoCl2-Al2O3 catalyst, the latter support having a higher specific surface area (i.e. 250 m2 g-1). In fact, CoCl2-Al2O3 is more performing than neat CoCl2 whereas the latter has been often showed as being one of the best catalytic systems. To further gain in reactivity, a new, alternative strategy has been envisaged. The Al2O3 was mixed together with a controlled amount of another oxide, namely TiO2. The CoCl2- Al2O3-TiO2(20 wt%) was found to be more reactive than CoCl2-Al2O3. All of these reactivity data are reported and briefly discussed hereafter. Further studies are in progress to highlight the reasons of such improved reactivity.

scholarly journals Adsorption of pharmaceuticals from aqueous solutions using biochar derived from cotton gin waste and guayule bagasse

Biochar ◽  
2020 ◽  
Author(s):  
Marlene C. Ndoun ◽  
Herschel A. Elliott ◽  
Heather E. Preisendanz ◽  
Clinton F. Williams ◽  
Allan Knopf ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
High Surface ◽  
Strong Interactions ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Cotton Gin Waste ◽  
Cotton Gin

Abstract Biochars produced from cotton gin waste (CG) and guayule bagasse (GB) were characterized and explored as potential adsorbents for the removal of pharmaceuticals (sulfapyridine-SPY, docusate-DCT and erythromycin-ETM) from aqueous solution. An increase in biochar pyrolysis temperature from 350 οC to 700 οC led to an increase in pH, specific surface area, and surface hydrophobicity. The electronegative surface of all tested biochars indicated that non-Coulombic mechanisms were involved in adsorption of the anionic or uncharged pharmaceuticals under experimental conditions. The adsorption capacities of Sulfapyridine (SPY), Docusate (DCT) and Erythromycin (ETM) on biochar were influenced by the contact time and solution pH, as well as biochar specific surface area and functional groups. Adsorption of these pharmaceutical compounds was dominated by a complex interplay of three mechanisms: hydrophobic partitioning, hydrogen bonding and π–π electron donor–acceptor (EDA) interactions. Despite weaker π–π EDA interactions, reduced hydrophobicity of SPY− and increased electrostatic repulsion between anionic SPY− and the electronegative CG biochar surface at higher pH, the adsorption of SPY unexpectedly increased from 40% to 70% with an increase in pH from 7 to 10. Under alkaline conditions, adsorption was dominated by the formation of strong negative charge-assisted H-bonding between the sulfonamide moiety of SPY and surface carboxylic groups. There seemed to be no appreciable and consistent differences in the extent of DCT and ETM adsorption as the pH changed. Results suggest the CG and GB biochars could act as effective adsorbents for the removal of pharmaceuticals from reclaimed water prior to irrigation. High surface area biochars with physico-chemical properties (e.g., presence of functional groups, high cation and anion exchange capacities) conducive to strong interactions with polar-nonpolar functionality of pharmaceuticals could be used to achieve significant contaminant removal from water. Graphic Abstract

Synthesis and Thermal Stability of HfO2 Nanoparticles

2010 ◽  
Vol 1256 ◽  
Author(s):  
Girija Shankar Chaubey ◽  
Yuan Yao ◽  
Julien Pierre Amelie Makongo Mangan ◽  
Pranati Sahoo ◽  
Pierre F. P. Poudeu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Large Scale ◽  
Average Diameter ◽  
Scale Production ◽  
Simple Method ◽  
Good Thermal Stability ◽  
Large Scale Production

AbstractA simple method is reported for the synthesis of monodispersed HfO2 nanoparticles by the ammonia catalyzed hydrolysis and condensation of hafnium (IV) tert-butoxide in the presence of surfactants at room temperature. Transmission electron microscopy shows faceted nanoparticles with an average diameter of 3-4 nm. As-synthesized nanoparticles are amorphous in nature and crystallize upon moderate heat treatment. The HfO2 nanoparticles have a narrow size distribution, large specific surface area and good thermal stability. Specific surface area was about 239 m2/g on as-prepared nanoparticle samples while those annealed at 500 °C have specific surface area of 221 m2/g indicating that there was no significant increase in particle size. This result was further confirmed by TEM images of nanoparticles annealed at 300 °C and 500 °C. X-ray diffraction studies of the crystallized nanoparticles revealed that HfO2 nanoparticles were monoclinic in structure. The synthetic procedure used in this work can be readily modified for large scale production of monodispersed HfO2 nanoparticles.

Structure and Catalytic Soot Combustion of Perovskite La-Mn-O Hollow Microfibers via Gel-Precursor Transformation Process

2012 ◽  
Vol 538-541 ◽  
pp. 2289-2292
Author(s):  
Xiao Xiao Meng ◽  
Feng Lin He ◽  
Jiang Ying Shen ◽  
Xiang Qian Shen
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Thermo Gravimetric Analysis ◽  
Transformation Process ◽  
High Catalytic Activity ◽  
Gravimetric Analysis ◽  
Soot Combustion ◽  
Aspect Ratios

The nanocrystalline perovskite La-Mn-O hollow microfibers were prepared by the gel-precursor transformation process from reagents of metal salts and citric acid. The gel precursor and resultant products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The specific surface area was measured by the Brunauere-Emmette-Teller method. The catalytic performance of soot combustion was evaluated by thermo-gravimetric analysis under model conditions. The nanocrystalline La-Mn-O hollow microfibers calcined at 650 °C for 6 h are characterized with diameters of 2-8 µm, aspect ratios (length/diameter) about 5-15, a micro-tunnel with an estimated ratio 1/3 of the hollow diameter to fiber diameter, and a high specific surface area of 36.7 m2/g that is 1.9 times higher than the counterpart nanosized powder. This nanocrystalline La-Mn-O hollow microfibers catalyst exhibit a high catalytic activity for the soot combustion, with a low T50 of 397°C, which is largely owing to the high surface area and the micro-tunnel structure.

scholarly journals N, S-Codoped Activated Carbon Material with Ultra-High Surface Area for High-Performance Supercapacitors

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1982
Author(s):  
Qinghua Yuan ◽  
Zhuwen Ma ◽  
Junbiao Chen ◽  
Zhenrui Huang ◽  
Zeming Fang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Material ◽  
High Surface ◽  
Koh Activation ◽  
Supercapacitor Electrode ◽  
Tobacco Stalk

The recycling of macromolecular biowastes has been a problem for the agriculture industry. In this study, a novel N, S-codoped activated carbon material with an ultrahigh specific area was produced for the application of a supercapacitor electrode, using tobacco stalk biowastes as the carbon source, KOH as the activating agents and thiourea as the doping agent. Tobacco stalk is mainly composed of cellulose, but also contains many small molecules and inorganic salts. KOH activation resulted in many mesopores, giving the tobacco stem-activated carbon a large specific surface area and double-layer capacitance. The specific surface area of the samples reached up to 3733 m2·g−1, while the maximum specific capacitance of the samples obtained was up to 281.3 F·g−1 in the 3-electrode tests (1 A·g−1). The doping of N and S elements raised the specific capacitance significantly, which could be increased to a value as high as 422.5 F·g−1 at a current density of 1 A·g−1 in the 3-electrode tests, but N, S-codoping also led to instability. The results of this article prove that tobacco stalks could be efficiently reused in the field of supercapacitors.

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