scholarly journals High Surface Area Ceria Nanoparticles via Hydrothermal Synthesis Experiment Design

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Stanislav Kurajica ◽  
Iva Minga ◽  
Martina Guliš ◽  
Vilko Mandić ◽  
Ivan Simčić
Keyword(s):  
Hydrothermal Synthesis ◽  
Surface Area ◽  
Fine Particles ◽  
High Surface ◽  
High Surface Area ◽  
Soot Oxidation ◽  
Nitrogen Adsorption ◽  
Synthesis Temperature ◽  
Oxidation Catalyst ◽  
Adsorption Desorption

Hydrothermal synthesis of CeO2was optimized on two reactant concentrations and synthesis temperature and duration, in order to achieve material having the greatest specific surface area (SSA). Taguchi method of experimental design was employed in evaluation of the relative importance of synthesis parameters. CeO2nanoparticles were characterized using X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. Optimum conditions for obtaining particles with greater SSA were calculated according to Taguchi’s model “the-higher-the-better.” Synthesis temperature was found to be the only parameter significant for enabling nanoparticles with greater SSA. Mesoporous nanocrystalline ceria with SSA as great as 226 m2 g−1was achieved, which is unprecedented for the hydrothermally synthesized ceria. The reason for this achievement was found in temperature dependence of the diffusion coefficient which, when low, favors nucleation yielding with fine particles, while when high it favors crystal growth and formation of one-dimensional structures. The occurrence of 1D-structure in sample exhibiting the smallest SSA was confirmed. Very fine crystallites with crystallite size as low as 5.9 nm have been obtained being roughly inverse proportional to SSA. Selected samples were tested as catalyst for soot oxidation. Catalyst morphology turned out to be decisive factor for catalytic activity.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

Preparation and Characterization of Silica-Alumina-Pillared Montmorillonites with High Surface Area

2008 ◽  
Vol 368-372 ◽  
pp. 1712-1715
Author(s):  
Hong Yan Xu ◽  
Xiao Jun Bao ◽  
Ting Hai Wang ◽  
Yong Gang Wang
Keyword(s):  
Surface Area ◽  
Layer Structure ◽  
High Surface ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bet Specific Surface Area ◽  
Silica Alumina ◽  
Novel Method ◽  
Pore Properties ◽  
Adsorption Desorption

The silica-alumina-pillared montmorillonite materials (SiAl-MMT) were developed by a novel method, which combined several techniques such as ion-exchange, intercalation and surfactant modification. The morphology, composite structure and pore properties of such composite materials, were investigated by X-ray powder diffraction (XRD), Scanning Electronic Microscopy (SEM), Fourier-transform infra-red (FTIR) spectra, as well as Nitrogen Adsorption-Desorption Isotherms. The layer structure of the prepared materials retained and their pore structures were found to be slit-shaped pores located between plate-like particles. The prepared SiAl-MMT materials had a BJH pore volume of 0.63cm3 g-1, a remarkably high BET specific surface area beyond 1000 m2 g-1, and a narrow pore size distribution in the mesoporous region 3.5-4 nm after thermal treatment at 600 °C.

scholarly journals Lignin Based Activated Carbon Using H3PO4 Activation

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2829
Author(s):  
Zhongzhi Yang ◽  
Roland Gleisner ◽  
Doreen H. Mann ◽  
Junming Xu ◽  
Jianchun Jiang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Surface Areas ◽  
Adsorption Desorption

Activated carbon (AC) with a very high surface area of over 2000 m2/g was produced from low sulfur acid hydrotropic lignin (AHL) from poplar wood using H3PO4 at a moderate temperature of 450 °C (AHL-AC6). ACs with similar surface areas were also obtained under the same activation condition from commercial hardwood alkali lignin and lignosulfonate. Initial evaluation of AC performance was carried out using nitrogen adsorption-desorption and dye adsorption. AHL-AC6 exhibited the best specific surface area and dye adsorption performance. Furthermore, the adsorption results of congo red (CR) and methylene blue (MB) showed AHL-AC6 had greater adsorption capacity than those reported in literature. The dye adsorption data fit to the Langmuir model well. The fitting parameter suggests the adsorption is nearly strong and near irreversible, especially for MB. The present study for the first time provided a procedure for producing AC from lignin with Brunauer–Emmett–Teller (BET) surface area >2000 m2/g using low cost and low environmental impact H3PO4 at moderate temperatures.

scholarly journals Synthesis and characterization of porous silica and polyaniline-porous silica composite materials with high surface area

2014 ◽  
Vol 49 (1) ◽  
pp. 1-8
Author(s):  
US Akhtar ◽  
MK Hossain ◽  
MS Miran ◽  
MYA Mollah
Keyword(s):  
Electron Microscopy ◽  
Pore Size ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Cylindrical Pore

Porous silica materials were synthesized from tetraethyl orthosilicate (TEOS) using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20) as template under acidic conditions which was then used to prepare polyaniline (PAni) and porous silica composites (PAnisilica) at a fixed molar ratio. These materials were characterized by nitrogen adsorption-desorption isotherm measured by Barrett-Joyner- Halenda (BJH) method and pore size distribution from desorption branch and surface area measured by the Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), TEM-energy dispersive X-ray (EDX) and Fourier transform infrared (FT-IR) spectroscopy. The composite maintains its structure even after the polymerization and the polymer is dispersed on the inorganic matrix. The rod-like porous silica was about 1?m to 1.5 ?m long and on an average the diameter was in the range of 300- 500 nm. The SEM and TEM images show well ordered 2d hexagonal pore, high specific surface area (850 m2g-1) and uniform pore size of ca. 6.5 nm in diameter. After incorporation of PAni inside the silica pore, framework of porous silica did not collapse and the surface area of the composite was as high as 434 m2g-1 which was 5.5 time higher than our previous report of 78.3 m2g-1. Due to shrinkage of the framework during the incorporation of aniline inside the silica, the pore diameter slightly increase to 7.5 nm but still showing Type IV isotherm and typical hysteresis loop H1 implying a uniform cylindrical pore geometry. DOI: http://dx.doi.org/10.3329/bjsir.v49i1.18847 Bangladesh J. Sci. Ind. Res. 49(1), 1-8, 2014

scholarly journals Synthesis and characterization of mesoporous materials with SBA and MCM structure types

Cerâmica ◽  
2019 ◽  
Vol 65 (376) ◽  
pp. 585-591
Author(s):  
R. A. Sacramento ◽  
O. M. S. Cysneiros ◽  
B. J. B. Silva ◽  
A. O. S. Silva
Keyword(s):  
Surface Area ◽  
Mesoporous Materials ◽  
High Surface ◽  
High Surface Area ◽  
Textural Properties ◽  
N2 Adsorption ◽  
Structure Directing Agent ◽  
Type Iv ◽  
Xrd Patterns ◽  
Adsorption Desorption

Abstract Mesoporous materials are promising structures for application in catalysis and adsorption due to high surface area and large pore size. Mesoporous materials were synthesized by the hydrothermal method with novel surfactants, distinct from those observed in the literature, in order to carry out a study of its structure and to obtain materials with better textural properties. The structures synthesized with the surfactants Igepal CO630 and Brij O20 presented the best results of specific surface area, 1074 and 1075 m2.g-1, respectively. The obtained materials were characterized by XRD, TG/DTG, N2 adsorption-desorption, and FTIR techniques. XRD patterns indicated that the highly ordered mesoporous silica structures, such as MCM-41 and MCM-48, using CTMABr as the structure-directing agent and the SBA-15, SBA-16 and other SBA structures using different block copolymers were obtained. Through N2 adsorption-desorption isotherms, it was observed type IV isotherms, attributed to mesoporous materials. The FTIR spectra presented similar behaviors with characteristic vibrational bands of MCM and SBA type materials.

scholarly journals Metal-Free Counter Electrode for Efficient Dye-Sensitized Solar Cells through High Surface Area and Large Porous Carbon

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
Pavuluri Srinivasu ◽  
Surya Prakash Singh ◽  
Ashraful Islam ◽  
Liyuan Han
Keyword(s):  
Electron Microscopy ◽  
Surface Area ◽  
Mesoporous Carbon ◽  
Counter Electrode ◽  
High Surface ◽  
High Surface Area ◽  
Dye Sensitized Solar Cells ◽  
Nitrogen Adsorption ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Highly efficient, large mesoporous carbon is fabricated as a metal-free counter electrode for dye-sensitized solar cells. The mesoporous carbon shows very high energy conversion efficiency of 7.1% compared with activated carbon. The mesoporous carbon is prepared and characterized by nitrogen adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The nitrogen adsorption data reveals that the material possesses BET specific surface area ca.1300 m2/g and pore diameter 4.4 nm. Hexagonal rod-like morphology and ordered pore structure of mesoporous carbon are confirmed by electron microscopy data. The better performance of this carbon material is greatly benefited from its ordered interconnected mesoporous structure and high surface area.

A high surface area flower-like Ni–Fe layered double hydroxide for electrocatalytic water oxidation reaction

2015 ◽  
Vol 44 (25) ◽  
pp. 11592-11600 ◽  
Author(s):  
Li-Jing Zhou ◽  
Xiaoxi Huang ◽  
Hui Chen ◽  
Panpan Jin ◽  
Guo-Dong Li ◽  
...  
Keyword(s):  
Surface Area ◽  
Layered Double Hydroxide ◽  
Water Oxidation ◽  
Oxidation Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Oxidation Catalyst ◽  
Double Hydroxide

A high surface area flower-like Ni–Fe LDH was shown to be a water oxidation catalyst.

One-Step Hydrothermal Synthesis of MoS2 Nano-Flowers with High Surface Area and Crystalline

2012 ◽  
Vol 531-532 ◽  
pp. 508-511 ◽  
Author(s):  
Yan Juan Li ◽  
Nan Li ◽  
Xiao Yan ◽  
Yue Chi ◽  
Qing Yuan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Synthesis ◽  
Surface Area ◽  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Ammonium Molybdate ◽  
Molar Ratio ◽  
Sulfur Source ◽  
One Step

One-step and controlled pH hydrothermal synthesis of transition metal disulfide using double molybdenum sources to synthesize MoS2 nano-flowers at low temperature was first reported. Anhydrous molybdenum pentachloride (MoCl5) and four sulfur ammonium molybdate ((NH4) 6Mo7O24•4H2O) were the molybdenum source and CS (NH2) 2 was the sulfur source. Through hydrothermal method, MoS2 was obtained at 180 °C. The pH value of system was controlled by adjusting the molar ratio of MoCl5 and (NH4) 6Mo7O24•4H2O. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area (BET) and transmission electron microscopy (TEM). The results show that the products were hexagonal MoS2 with a high crystalline and flower-like structure consisted of small particles. The thickness of petals is a few to tens of nanometers. By changing the molar ratio of molybdenum sources, the resultant phase from the mixed phase transited to the pure phase and the purity of synthetic MoS2 crystal increaseed.

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