scholarly journals Effect of Ultrasonic Irradiation on Preparation and Properties of Ionogels

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Yogendra Lal Verma ◽  
Manish Pratap Singh ◽  
Rajendra Kumar Singh
Keyword(s):  
Ultrasonic Irradiation ◽  
Sol Gel ◽  
Porous Silica ◽  
Porous Matrix ◽  
Silica Matrix ◽  
Tetraethyl Orthosilicate ◽  
Aliphatic Chain ◽  
One Pot ◽  
Bet Analysis ◽  
Vibrational Bands

Silica-gel matrices containing ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate viz. ionogels have been synthesized using one-pot nonhydrolytic sol-gel method and taking tetraethyl orthosilicate (TEOS) as starting precursor. Effect of ultrasonic irradiation on pore parameters of ionogels and vibrational properties of the IL upon confinement in the porous matrix has been investigated. The synthesized gels have been characterized by BET, DSC, TGA, and FTIR. BET analysis shows some changes in the pore parameters due to ultrasonic irradiation. DSC results indicate shift in glass transition temperature upon confinement of the IL. The FTIR spectra show changes in vibrational bands on confinement, particularly, the bands related to the imidazolium ring; aliphatic chain and anionPF6 −of the IL are found to shift upon confinement in porous silica matrix obtained due to ultrasonic irradiation. Ultrasonic irradiation has been found to affect the gelation dynamics and kinetics and pore parameters.

Macrocellular Titanosilicate Monoliths as Highly Efficient Structured Olefin Epoxidation Catalysts

2019 ◽  
Author(s):  
Valentin Smeets ◽  
Ludivine van den Biggelaar ◽  
Tarek Barakat ◽  
Eric M. Gaigneaux ◽  
Damien Debecker
Keyword(s):  
Sol Gel ◽  
Silica Matrix ◽  
Flow Mode ◽  
Tetrahedral Coordination ◽  
Excellent Performance ◽  
One Pot ◽  
Templating Method ◽  
Porous Texture ◽  
Internal Phase ◽  
Epoxidation Of Cyclohexene

Self-standing macrocellular titanosilicate monolith foams are obtained using a one-pot sol-gel route and show excellent performance in the epoxidation of cyclohexene. Thanks to the High Internal Phase Emulsion (HIPE) templating method, the materials feature a high void fraction, a hierarchically porous texture and good mechanical strength. Highly dispersed Ti species can be incorporated in tetrahedral coordination the silica matrix. These characteristics allow the obtained ‘SiTi(HIPE)’ materials to reach high catalytic turnover in the epoxidation of cyclohexene. The monoliths can advantageously be used to run the reaction in continuous flow mode.<br>

Bioencapsulation in Sol-Gel Glasses

1998 ◽  
Vol 519 ◽  
Author(s):  
L. Bergogne ◽  
S. Fennouh ◽  
J. Livage ◽  
C. Roux
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Matrix ◽  
Whole Cells ◽  
The Past ◽  
Wide Range ◽  
Activity Of Enzymes ◽  
Gel Glasses ◽  
Micro Organisms

AbstractBioencapsulation in sol-gel materials has been widely studied during the past decade. Trapped species appear to retain their bioactivity in the porous silica matrix. Small analytes can diffuse through the pores allowing bioreactions to be performed in-situ, inside the sol-gel glass. A wide range of biomolecules and micro-organisms have been encapsulated. The catalytic activity of enzymes is used for the realization of biosensors or bioreactors. Antibody-antigen recognition has been shown to be feasible within sol-gel matrices. Trapped antibodies bind specifically the corresponding haptens and can be used for the detection of traces of chemicals. Even whole cells are now encapsulated without any alteration of their cellular organization. They can be used for the production of chemicals or as antigens for immunoassays.

Preparation of Porous Silica by Microemulsion Coupling with Sol-Gel Method

2010 ◽  
Vol 113-116 ◽  
pp. 2266-2270
Author(s):  
Jing Li ◽  
Wei Xue ◽  
Yong Zhao ◽  
Zhi Miao Wang
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Tetraethyl Orthosilicate ◽  
Large Specific Surface Area ◽  
Silicon Source ◽  
Effect Of Solvent ◽  
Texture Properties ◽  
Sol Gel Process ◽  
Novel Method ◽  
Hcl Concentration

A novel method of microemulsion coupling with sol–gel process was used for preparation of porous silica using tetraethyl orthosilicate as silicon source. Effect of solvent and catalyst on the surface texture properties was investigated respectively. The results showed that porous silica with large specific surface area (738.65 m2/g) and high pore volume (2.01 cm3/g) was obtained. However, the mesopores in silica were arranged in disorder and showed great ununiformity in shape and arrangement. To obtain porous silica with desired texture properties, an appropriate dosage of ethanol and higher HCl concentration were needed.

scholarly journals Non-Hydrolytic Sol-Gel Route to a Family of Hybrid Mesoporous Aluminosilicate Ethanol Dehydration Catalysts

2020 ◽  
Author(s):  
Ales Styskalik ◽  
Imène Kordoghli ◽  
Claude Poleunis ◽  
Arnaud Delcorte ◽  
Denis Dochain ◽  
...  
Keyword(s):  
Gas Phase ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Silica Matrix ◽  
Ethanol Dehydration ◽  
One Pot ◽  
Water Contact ◽  
Hybrid Silica ◽  
Mesoporous Aluminosilicate ◽  
Improved Performance

Organic-inorganic hybrid materials are nowadays intensely studied for potential applications in heterogeneous catalysis because their properties and catalytic behavior differ from pristine inorganic counterparts. The organic groups at the catalyst surface can modify not only its hydrophilicity, but also acidity, hydrothermal stability, porosity, etc. In some cases, such properties alteration leads to improved catalytic performance in terms of activity, selectivity, or stability. However, the choice of organic groups stays relatively narrow, as most reports focus on pendant methyl groups. Here, a series of mesoporous hybrid aluminosilicate materials containing various organic groups was prepared in one pot by non-hydrolytic sol-gel (NHSG). Both aromatic and aliphatic, pendant and bridging organic groups were incorporated. The presence of the organic groups in the bulk and at the outermost surface of the materials was verified by solid-state NMR and ToF-SIMS, respectively. Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. The organically modified mesoporous aluminosilicate samples were tested as catalysts in the gas phase ethanol dehydration (which relies on solid acids) and most of them outperformed the purely inorganic catalyst benchmark. While a direct influence of surface hydrophilicity or hydrophobicity (as probed by water sorption and water contact angle measurements) appeared unlikely, characterization of acidity (IR-pyridine) revealed that the improved performance for hybrid catalysts can be correlated with a modification of the acidic properties. In turn, acidity is determined by the quality of the dispersion of Al centers in the form of isolated sites in the hybrid silica matrix. All in all, this study establishes a "ranking" for a variety of organic groups in terms of their effect on gas-phase ethanol dehydration to ethylene; ethylene yield decreases in this order: bridging xylylene ≈ pendant methyl > pendant benzyl > bridging methylene ≈ inorganic benchmark (no organic groups) > bridging ethylene.<br>

scholarly journals Magnetic Study of CuFe2O4-SiO2 Aerogel and Xerogel Nanocomposites

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2680
Author(s):  
Alizé V. Gaumet ◽  
Francesco Caddeo ◽  
Danilo Loche ◽  
Anna Corrias ◽  
Maria F. Casula ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Sol Gel ◽  
Porous Silica ◽  
Chemical Properties ◽  
Silica Matrix ◽  
Superparamagnetic Nanoparticles ◽  
Blocking Temperature ◽  
Copper Ferrite ◽  
Transmission Electron ◽  
Magnetic Features

CuFe2O4 is an example of ferrites whose physico-chemical properties can vary greatly at the nanoscale. Here, sol-gel techniques are used to produce CuFe2O4-SiO2 nanocomposites where copper ferrite nanocrystals are grown within a porous dielectric silica matrix. Nanocomposites in the form of both xerogels and aerogels with variable loadings of copper ferrite (5 wt%, 10 wt% and 15 wt%) were synthesized. Transmission electron microscopy and X-ray diffraction investigations showed the occurrence of CuFe2O4 nanoparticles with average crystal size ranging from a few nanometers up to around 9 nm, homogeneously distributed within the porous silica matrix, after thermal treatment of the samples at 900 °C. Evidence of some impurities of CuO and -Fe2O3 was found in the aerogel samples with 10 wt% and 15 wt% loading. DC magnetometry was used to investigate the magnetic properties of these nanocomposites, as a function of the loading of copper ferrite and of the porosity characteristics. All the nanocomposites show a blocking temperature lower than RT and soft magnetic features at low temperature. The observed magnetic parameters are interpreted taking into account the occurrence of size and interaction effects in an ensemble of superparamagnetic nanoparticles distributed in a matrix. These results highlight how aerogel and xerogel matrices give rise to nanocomposites with different magnetic features and how the spatial distribution of the nanophase in the matrices modifies the final magnetic properties with respect to the case of conventional unsupported nanoparticles.

Macrocellular Titanosilicate Monoliths as Highly Efficient Structured Olefin Epoxidation Catalysts

2019 ◽  
Author(s):  
Valentin Smeets ◽  
Ludivine van den Biggelaar ◽  
Tarek Barakat ◽  
Eric M. Gaigneaux ◽  
Damien Debecker
Keyword(s):  
Sol Gel ◽  
Silica Matrix ◽  
Flow Mode ◽  
Tetrahedral Coordination ◽  
Excellent Performance ◽  
One Pot ◽  
Templating Method ◽  
Porous Texture ◽  
Internal Phase ◽  
Epoxidation Of Cyclohexene

Self-standing macrocellular titanosilicate monolith foams are obtained using a one-pot sol-gel route and show excellent performance in the epoxidation of cyclohexene. Thanks to the High Internal Phase Emulsion (HIPE) templating method, the materials feature a high void fraction, a hierarchically porous texture and good mechanical strength. Highly dispersed Ti species can be incorporated in tetrahedral coordination the silica matrix. These characteristics allow the obtained ‘SiTi(HIPE)’ materials to reach high catalytic turnover in the epoxidation of cyclohexene. The monoliths can advantageously be used to run the reaction in continuous flow mode.<br>

One pot synthesis of hierarchical porous silica membrane material with dispersed Pt nanoparticles using a microwave-assisted sol–gel route

2008 ◽  
Vol 18 (36) ◽  
pp. 4274 ◽  
Author(s):  
Christelle Yacou ◽  
Marie-Laure Fontaine ◽  
André Ayral ◽  
Patrick Lacroix-Desmazes ◽  
Pierre-Antoine Albouy ◽  
...  
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Pt Nanoparticles ◽  
Membrane Material ◽  
Silica Membrane ◽  
One Pot ◽  
Microwave Assisted ◽  
One Pot Synthesis ◽  
Hierarchical Porous

Sol-gel hot injection synthesis of ZnO nanoparticles into a porous silica matrix and reaction mechanism

2017 ◽  
Vol 119 ◽  
pp. 270-276 ◽  
Author(s):  
Ahmed Barhoum ◽  
Guy Van Assche ◽  
Hubert Rahier ◽  
Manuel Fleisch ◽  
Sara Bals ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Zno Nanoparticles ◽  
Sol Gel ◽  
Porous Silica ◽  
Silica Matrix ◽  
Hot Injection

Sol-gel synthesis and properties of compositions containing heteropoly compounds in porous silica matrix

2014 ◽  
Vol 40 (1) ◽  
pp. 8-16 ◽  
Author(s):  
S. V. Khalameida ◽  
V. V. Sydorchuk ◽  
J. Skubiszewska-Zięba ◽  
R. Leboda ◽  
V. A. Zazhigalov
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Matrix ◽  
Heteropoly Compounds ◽  
Sol Gel Synthesis
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