Synthesis of High-Surface-Area SiC through a Modified Sol−Gel Route:  Control of the Pore Structure

2004 ◽  
Vol 43 (16) ◽  
pp. 4732-4739 ◽  
Author(s):  
Puneet Gupta ◽  
William Wang ◽  
Liang-Shih Fan
Keyword(s):  
Pore Structure ◽  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area

Spectroscopic Characterization of Mixed Titania-Silica Xerogel Catalysts

1999 ◽  
Vol 590 ◽  
Author(s):  
MA Holland ◽  
DM Pickup ◽  
G Mountjoy ◽  
SC Tsang ◽  
GW Wallidge ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Pore Structure ◽  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Silica Xerogel ◽  
Test Reaction ◽  
Saxs Data ◽  
Surface Areas

ABSTRACTThe synthesis of high surface area (TiO2)0.18(SiO2)0.82xerogels has been achieved using the sol-gel route. Heptane washing was used before the drying stage to minimise capillary pressure and hence preserve pore structure and maximise the surface area. The as-prepared xerogels were tested for their catalytic activity using the epoxidation of cyclohexene with tert-butyl hydrogen peroxide (TBHP) as a test reaction. Surface areas up to 450 m2g-1 were achieved with excellent selectivities and reasonable percent conversions. SAXS data has identified that heptane washing during drying, in general, results in a preservation of the pore structure, and produces more effective catalysts with higher surface areas and larger pore diameters. Fr-IR spectroscopy has revealed that the catalytic activity is dependant upon the number of Si-O-Ti linkages, inferring intimate mixing of the precursors at the atomic level. XANES data reveals the presence of reversible 4/6-fold Ti sites that are thought to be ‘active’ catalytic sites. The most effective catalyst was produced with a calcination temperature of 500°C, and a heating rate of 5 °Cmin-l

High-Surface-Area Alumina-Silica Nanocatalysts Prepared by a Hybrid Sol-Gel Route Using a Boehmite Precursor

2010 ◽  
Vol 93 (12) ◽  
pp. 4047-4052 ◽  
Author(s):  
Padmaja Parameswaran Nampi ◽  
Padmanabhan Moothetty ◽  
Wilfried Wunderlich ◽  
Frank John Berry ◽  
Michael Mortimer ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area

Synthesis and structural characteristics of high surface area TiO2 aerogels by ultrasonic-assisted sol–gel method

2018 ◽  
Vol 29 (7) ◽  
pp. 075702 ◽  
Author(s):  
Feng Qingge ◽  
Cai Huidong ◽  
Lin Haiying ◽  
Qin Siying ◽  
Liu Zheng ◽  
...  
Keyword(s):  
Surface Area ◽  
Structural Characteristics ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Gel Method ◽  
Sol Gel Method ◽  
Ultrasonic Assisted

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.

Aqueous colloidal sol–gel route to synthesize nanosized ceria-doped titania having high surface area and increased anatase phase stability

2007 ◽  
Vol 43 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Pradeepan Periyat ◽  
K. V. Baiju ◽  
P. Mukundan ◽  
P. Krishna Pillai ◽  
K. G. K. Warrier
Keyword(s):  
Surface Area ◽  
Phase Stability ◽  
Anatase Phase ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Doped Titania

scholarly journals Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 423 ◽  
Author(s):  
Kamonchanok Roongraung ◽  
Surawut Chuangchote ◽  
Navadol Laosiripojana
Keyword(s):  
Formic Acid ◽  
Surface Area ◽  
Gluconic Acid ◽  
Photocatalytic Oxidation ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Value Added ◽  
Incipient Wetness Impregnation ◽  
Microwave Assisted

TiO2-based photocatalysts synthesized by the microwave-assisted sol-gel method was tested in the photocatalytic glucose conversion. Modifications of TiO2 with type-Y zeolite (ZeY) and metals (Ag, Cu, and Ag-Cu) were developed for increasing the dispersion of TiO2 nanoparticles and increasing the photocatalytic activity. Effects of the TiO2 dosage to zeolite ratio (i.e., TiO2/ZeY of 10, 20, 40, and 50 mol %) and the silica to alumina ratio in ZeY (i.e., SiO2:Al2O3 of 10, 100, and 500) were firstly studied. It was found that the specific surface area of TiO2/ZeY was 400–590 m2g−1, which was higher than that of pristine TiO2 (34.38 m2g−1). The good properties of 20%TiO2/ZeY photocatalyst, including smaller particles (13.27 nm) and high surface area, could achieve the highest photocatalytic glucose conversion (75%). Yields of gluconic acid, arabinose, xylitol, and formic acid obtained from 20%TiO2/ZeY were 9%, 26%, 4%, and 35%, respectively. For the effect of the silica to alumina ratio, the highest glucose conversion was obtained from SiO2:Al2O3 ratio of 100. Interestingly, it was found that the SiO2:Al2O3 ratio affected the selectivity of carboxylic products (gluconic acid and formic acid). At a low ratio of silica to alumina (SiO2:Al2O3 = 10), higher selectivity of the carboxylic products (gluconic acid = 29% and formic acid = 32%) was obtained (compared with other higher ratios). TiO2/ZeY was further loaded by metals using the microwave-assisted incipient wetness impregnation technique. The highest glucose conversion of 96.9 % was obtained from 1 wt. % Ag-TiO2 (40%)/ZeY. Furthermore, the bimetallic Ag-Cu-loaded TiO2/ZeY presented the highest xylitol yield of 12.93%.

Coupling Sol-Gel Synthesis and Microwave-Assisted Techniques: A New Route from Amorphous to Crystalline High-Surface-Area Aluminium Fluoride

2008 ◽  
Vol 14 (20) ◽  
pp. 6205-6212 ◽  
Author(s):  
Damien Dambournet ◽  
Gehan Eltanamy ◽  
Alexandre Vimont ◽  
Jean-Claude Lavalley ◽  
Jean-Michel Goupil ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Microwave Assisted ◽  
Aluminium Fluoride ◽  
Sol Gel Synthesis

scholarly journals Effect of Sodium Periodate on the Adsorption Capacity of Silica-Lignin from Rice Husk on Chromium(VI)

2019 ◽  
Vol 22 (6) ◽  
pp. 242-249 ◽  
Author(s):  
Yati B. Yuliyati ◽  
Solihudin Solihudin ◽  
Atiek Rostika Noviyanti
Keyword(s):  
Adsorption Capacity ◽  
Surface Area ◽  
Sodium Periodate ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Adsorption Model ◽  
Chromium Vi ◽  
Reactive Groups ◽  
Isotherm Adsorption

Reactive groups such as silanol, hydroxyl, and carbonyl groups in silica-lignin composites play a role in binding to chromium(VI) ions. The activation of functional groups in silica-lignin can be increased by the addition of an activator such as sodium periodate, which can also oxidize the lignin monomer (guaiasil) to ortho-quinone. This study aimed to obtain silica-lignin composites from rice husks activated by sodium periodate with a high surface area. Composite absorption was tested on chromium(VI) adsorption. Silica-lignin isolation was carried out by using the sol-gel method at concentrations of sodium hydroxide 5, 10, 15, and 20% (b/b). Silica-lignin activated with sodium periodate 10% (b/b) had the smallest particle size of about 8μm, with a surface area of 14.0888 m2.g-1 and followed Halsey isotherm adsorption model, with an adsorption capacity of 0.3054 mg.g-1.

scholarly journals Nano metal fluorides: small particles with great properties

ChemTexts ◽  
2020 ◽  
Vol 6 (3) ◽  
Author(s):  
Erhard Kemnitz ◽  
Stefan Mahn ◽  
Thoralf Krahl
Keyword(s):  
Surface Area ◽  
State Of The Art ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Chemical Properties ◽  
Lewis Acidity ◽  
Small Particles ◽  
Specific Chemical ◽  
Metal Fluorides

Abstract The recently developed fluorolytic sol–gel route to metal fluorides opens a very broad range of both scientific and technical applications of the accessible high surface area metal fluorides, many of which have already been applied or tested. Specific chemical properties such as high Lewis acidity and physical properties such as high surface area, mesoporosity and nanosize as well as the possibility to apply metal fluorides on surfaces via a non-aqueous sol make the fluorolytic synthesis route a very versatile one. The scope of its scientific and technical use and the state of the art are presented.

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