Study on the Sol-Gel Process of TEOS by React-IR

2011 ◽  
Vol 110-116 ◽  
pp. 1401-1405 ◽  
Author(s):  
Hua Hua Zhou ◽  
Wei Xue ◽  
Fang Li ◽  
Yan Fei Qin
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Polymerization Rate ◽  
Condensation Polymerization ◽  
Acid Base ◽  
Nucleophilic Reaction ◽  
Sol Gel Process ◽  
Acidic Conditions ◽  
Adsorption Desorption ◽  
Meso Scale

Porous silica was prepared through TEOS sol-gel process catalyzed by acid-base joint catalyst, and the process was monitored by React IRTM. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. Under acidic conditions, H+ attacks –OR group of TEOS firstly, then the electronegative Cl- can attack Si4+ and make TEOS be hydrolyzed. When basic catalyst was added, the reaction will be accelerated. The promotion effect of base is attributed to the direct nucleophilic reaction mechanism and the smaller size of OH-, which can attack Si more easily. Thirdly, silanol, generated from TEOS hydrolyzation, attract Si-OR or other Si-OH around; thereby resulting rapid dehydration or de-alcohol reaction. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle like conglomeration. The porous silica was characterized by SEM and N2 adsorption-desorption technique. It was shown that the silica had large specific surface area, 818.5 m2/g, and relatively narrow distribution of pore size in meso-scale. Futhermore, the mesopores were nonuniform in shape and arrangement.

Synthesis of TEOS-Based Silica Spherical Particles by Sol-Gel Process

2013 ◽  
Vol 773 ◽  
pp. 606-610
Author(s):  
Jing Li ◽  
Hong Qi Zhang ◽  
Wei Xue
Keyword(s):  
Sol Gel ◽  
Silica Particles ◽  
Electron Cloud ◽  
Polymerization Rate ◽  
Spherical Particles ◽  
Condensation Polymerization ◽  
Spherical Silica ◽  
Sol Gel Process ◽  
Spherical Silica Particles

Spherical silica particles, with mean sizes about 1.2 μm, were prepared through TEOS sol-gel process catalyzed by ammonia. The silica particles have a smooth surface and a small specific surface area, 3.4 m2/g. The sol-gel process was monitored by React IRTMusing an in-situ technique. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. With the adding of ammonia, OH-anion attacks Si atomic nucleus directly and makes it showing negative electricity. Therefore the electron cloud shifts to the OR group on the other side. This weakens the Si-O bond and results in the removal of the OR group. Furthermore, silanol, generated from TEOS hydrolyzation, attracts Si-OR or other Si-OH around; thereby resulting rapid dehydration or dealcohol between molecular. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle.

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 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.

Textural characterization of porous silica films prepared by the sol–gel process

2004 ◽  
pp. 227-231
Author(s):  
G. L. T. Nascimento ◽  
L. M. Seara ◽  
B. R. A. Neves ◽  
N. D. S. Mohallem
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Films ◽  
Textural Characterization ◽  
Sol Gel Process

Adsorption–desorption kinetics of silica coated on textile fabrics by the sol–gel process

2019 ◽  
Vol 17 (2) ◽  
pp. 371-380 ◽  
Author(s):  
Mohamed El messoudi ◽  
Aicha Boukhriss ◽  
Omar Cherkaoui ◽  
M’hammed El kouali ◽  
Said Gmouh
Keyword(s):  
Sol Gel ◽  
Desorption Kinetics ◽  
Textile Fabrics ◽  
Sol Gel Process ◽  
Adsorption Desorption ◽  
Kinetics Of

Synthesis of bimodal porous silica from rice husk ash via sol–gel process using chitosan as template

2008 ◽  
Vol 62 (10-11) ◽  
pp. 1476-1479 ◽  
Author(s):  
T. Witoon ◽  
M. Chareonpanich ◽  
J. Limtrakul
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Sol Gel ◽  
Porous Silica ◽  
Sol Gel Process

Preparation of SiO2 Antireflective Film by a Base/Acid Two-Step Catalyzed Sol-Gel Process

2013 ◽  
Vol 860-863 ◽  
pp. 845-848 ◽  
Author(s):  
De Yi Li ◽  
Kun Peng ◽  
Ling Ping Zhou ◽  
Jia Jun Zhu
Keyword(s):  
Raw Materials ◽  
Salt Spray ◽  
Sol Gel ◽  
Acid Base ◽  
Gel Method ◽  
Antireflective Film ◽  
Sol Gel Process ◽  
Acid Catalyzed ◽  
Antireflective Films ◽  
Silica Sols

SiO2 antireflective films were prepared by two-step catalyzed sol-gel method with TEOS as the raw materials, acid and ammonia as catalyst. Effects of the ratio of acid-catalyzed and base-catalyzed silica sols on the transmittance and stability of SiO2 film were investigated. The transmittance can be adjusted by change the ratio of base-catalyzed sols, and a higher transmittance can be obtained in the higher ratio of base-catalyzed coatings. A higher stability of SiO2 film in salt spray can be obtained in higher ratio of acid-catalyzed AR coatings. AR coatings with excellent transmittance and stability can be obtained by adjusting the ratio of acid/base catalyzed silica sols.

Thermoplastic and thermosetting properties of polyphenylsilsesquioxane particles prepared by two-step acid-base catalyzed sol-gel process

2007 ◽  
Vol 41 (3) ◽  
pp. 217-222 ◽  
Author(s):  
Kenji Takahashi ◽  
Kiyoharu Tadanaga ◽  
Atsunori Matsuda ◽  
Akitoshi Hayashi ◽  
Masahiro Tatsumisago
Keyword(s):  
Sol Gel ◽  
Acid Base ◽  
Sol Gel Process

Synthesis of NaY Zeolite and their CO2 Adsorption Properties

2014 ◽  
Vol 1033-1034 ◽  
pp. 399-403
Author(s):  
Ren Juan Ma ◽  
Yong Quan Xu ◽  
Yu Min Liu ◽  
Rui Hong Zhao ◽  
Xiang Jing Zhang ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Gas Flow ◽  
Separation Efficiency ◽  
Sol Gel ◽  
Fixed Bed ◽  
Nay Zeolite ◽  
Sol Gel Process ◽  
Curve Method ◽  
Ft Ir ◽  
Adsorption Desorption

NaY zeolite was prepared by a simple sol-gel process. The prepared NaY was characterized by XRD,FT-IR,N2adsorption/desorption isotherms, and scanning electron microscope (SEM). The CO2dynamic adsorption/desorption performance of NaY was tested under atmospheric pressure using adsorption curve method in the fixed bed. The results demonstrate that NaY offeres high separation efficiency for CO2against N2. To further identify the most adsorption conditions, different adsorption temperatures and gas flow rates were investigated respectively. It is shown that NaY zeolite has the largest adsorption capacity of 88 mg/g adsorbent at 60°C,50ml/min, and the sample maintains still strong adsorption capacity and stable structure during 6 consecutive test cycles, which exhibits its stable adsorption/desorption behavior.

Sign in / Sign up

Export Citation Format

Share Document