The ethylene glycol-mediated sol-gel synthesis of nano AlF3: structural and acidic properties after different post treatments

2021 ◽  
Author(s):  
Wei Mao ◽  
Yanbo Bai ◽  
Zhaohua Jia ◽  
yue qin ◽  
bo wangbo ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Surface Acidity ◽  
Sol Gel ◽  
Acidic Properties ◽  
Sol Gel Process ◽  
Sol Gel Synthesis

In this work, the structure and surface acidity of nano AlF3 prepared by the ethylene glycol-mediated sol-gel process, followed by different post treatments including post-fluorination and calcination, were systematically investigated....

Sol-Gel Synthesis and Characterisation of Nanoscopic FeF3-MgF2Heterogeneous Catalysts with Bi-Acidic Properties

ChemCatChem ◽  
2013 ◽  
Vol 5 (8) ◽  
pp. 2223-2232 ◽  
Author(s):  
Ying Guo ◽  
Piotr Gaczyński ◽  
Klaus-Dieter Becker ◽  
Erhard Kemnitz
Keyword(s):  
Sol Gel ◽  
Acidic Properties ◽  
Sol Gel Synthesis

Crystalline and amorphous aluminosilicates with different pore structures for the synthesis of pyridines

2017 ◽  
Vol 41 (5) ◽  
pp. 253-261 ◽  
Author(s):  
Nellya G. Grigor'eva ◽  
Nadezhda A. Filippova ◽  
Marat R. Agliullin ◽  
Boris I. Kutepov ◽  
Nama Narender
Keyword(s):  
Sol Gel ◽  
Catalytic Synthesis ◽  
Maximum Amount ◽  
Macroporous Structure ◽  
Acidic Properties ◽  
Mesoporous Aluminosilicates ◽  
Zeolite Framework ◽  
Narrow Pore Size Distribution ◽  
Heterogeneous Catalytic ◽  
Sol Gel Synthesis

The heterogeneous catalytic synthesis of pyridine and methylpyridines (picolines) was carried out by the reaction of ethanol with formaldehyde and ammonia over aluminosilicates with different acidic properties and textural characteristics: zeolite framework-type FAU in H-form with microporous (H-Y) and micro-meso-macroporous structure (H-Y-mmm) and mesoporous aluminosilicates, obtained by sol-gel synthesis in an alkaline medium (ASM-1) and under variable pH (ASM-2). It is shown that the highest catalytic activity is characteristic of ASM-2 (Si/Al = 40) with a narrow pore size distribution within the range 2 to 5 nm and containing strongly acidic bridging Si–OH–Al groups on the surface. The products of the reaction of ethanol with formaldehyde and ammonia on the catalysts studied are dominated by picolines; the maximum amount of picolines (60%) is formed on the H-Y-mmm and aluminosilicate ASM-2 samples.

Effect of Sintering Time on the Phase Composition in PFN Ceramics Prepared by Sol-Gel Process

2009 ◽  
Vol 409 ◽  
pp. 317-321 ◽  
Author(s):  
Helena Bruncková ◽  
Ľubomír Medvecký ◽  
Ján Mihalik
Keyword(s):  
Perovskite Phase ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Molar Ratio ◽  
Sintering Time ◽  
Sol Gel Process ◽  
Sol Gel Synthesis ◽  
Spherical Grains ◽  
Bimodal Grain Size ◽  
Iron Niobate

Lead iron niobate Pb(Fe0.5Nb0.5)O3 (PFN) ceramics were prepared using sol-gel synthesis by mixing acetates Pb and Fe with Nb-ethylene glycol-tartarate (Pechini) complex at 80°C, calcination of gels at 600°C and sintering at 1150°C for various times. The metastable pyrochlore phase Pb3Nb4O13 in stoichiometric precursor was partially decomposed to perovskite phase Pb(Fe0.5Nb0.5)O3 in ceramics sintered at temperature of 1150°C for 2, 4 and 6 hours. Excess of Pb in molar ratio (Pb:Fe:Nb = 1.2:0.5:0.5) caused the increase of the content of the perovskite phase (~50 vol.%) in nonstoichiometric PFN ceramics sintered at 1150°C for 6 hours while the decrease in perovskite phase content was found in stoichiometric PFN ceramics (~16 vol.%). In microstructures of PFN ceramics sintered at 1150°C for different times, the bimodal grain size distribution was observed with small spherical grains of perovskite phase and larger octahedral grains of pyrochlore phase. EDX analysis confirm that complex types of pyrochlore phases that differ in iron content were present in ceramics.

scholarly journals Formation of nanoscopic CaF2via a fluorolytic sol–gel process for antireflective coatings

2015 ◽  
Vol 3 (8) ◽  
pp. 1716-1723 ◽  
Author(s):  
Alexander Rehmer ◽  
Kerstin Scheurell ◽  
Erhard Kemnitz
Keyword(s):  
Sol Gel ◽  
Nano Particles ◽  
Antireflective Coatings ◽  
Sol Gel Process ◽  
Sol Gel Synthesis ◽  
First Time

For the first time transparent antireflective CaF2-coatings were prepared from clear CaF2-sols obtained via the fluorolytic sol–gel synthesis and containing homo-dispersed CaF2 nano-particles.

Sol-gel synthesis of biocompatible silica-chitosan hybrids and hydrophobic coatings

2008 ◽  
Vol 23 (8) ◽  
pp. 2053-2060 ◽  
Author(s):  
S. Smitha ◽  
P. Shajesh ◽  
P. Mukundan ◽  
K.G.K. Warrier
Keyword(s):  
Condensation Reaction ◽  
Sol Gel ◽  
Visible Region ◽  
Reaction Medium ◽  
Optical Transmittance ◽  
Hydrophobic Coatings ◽  
Glass Substrates ◽  
Sol Gel Process ◽  
Sol Gel Synthesis

A new organic–inorganic hybrid synthesized through a sol-gel process starting from alkoxysilane and chitosan is reported. Functionalization of the hybrid was effected through in situ hydrolysis–condensation reaction of methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) in the reaction medium. The process yields highly transparent and hydrophobic silica–chitosan hybrids. The hybrid gel was investigated with respect to chemical modification, thermal degradation, hydrophobicity, and transparency under the ultraviolet-visible region. The extent of hydrophobicity had been tailored by varying the precursor ratio. SiO2–chitosan–MTMS hybrids showed a higher thermal stability than SiO2–chitosan–VTMS (SCV) hybrids with respect to hydrophobicity. Condensation of silsesquioxanes generated from the hydrolysis of MTMS and VTMS over the silica-chitosan particles impart hydrophobicity to the hybrid. The coatings of functionalized SiO2–chitosan precursor sol on glass substrates showed nearly 100% optical transmittance in the visible region. The present hybrid material may find application in optics and other industries.

scholarly journals Sol-gel synthesis of α-Al2O3 with enhanced porosity via dicarboxylic acid templating

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Simon Carstens ◽  
Christian Splith ◽  
Dirk Enke
Keyword(s):  
Citric Acid ◽  
Thermal Analyses ◽  
Sol Gel ◽  
Dicarboxylic Acids ◽  
Precise Control ◽  
Sol Gel Process ◽  
Successful Establishment ◽  
The One ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

AbstractOne of the major routes to synthesize macroporous α-Al2O3 is the sol-gel process in presence of templates. Templates include polymers as well as carboxylic acids, such as citric acid. By careful choice of the template, pore diameters can be adjusted between 110 nm and several µm. We report the successful establishment of plain short-chain dicarboxylic acids (DCA) as porogenes in the sol-gel synthesis of macroporous α-Al2O3. By this extension of the recently developed synthesis route, a very precise control of pore diameters is achieved, in addition to enhanced macropore volumes in α-Al2O3. The formation mechanism thereof is closely related to the one postulated for citric acid, as thermal analyses show. However, since branching in the DCA-linked alumina nuclei is not possible, close monomodal pore width distributions are attained, which are accompanied by enhanced pore volumes. This is a significant improvement in terms of controlled enhanced porosity in the synthesis of macroporous α-Al2O3.

Study of Pseudoboehmite Synthesis by Sol-Gel Process

2006 ◽  
Vol 45 ◽  
pp. 260-265 ◽  
Author(s):  
Antônio Hortêncio Munhoz Jr. ◽  
Leila Figueiredo de Miranda ◽  
G.N. Uehara
Keyword(s):  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Sol Gel Process ◽  
Different Temperatures ◽  
Sol Gel Synthesis

A pseudoboehmite was obtained by sol-gel synthesis using aluminum nitrate as precursor. It was used a 2n full factorial design for studying the effect of the temperature of synthesis, the concentration of ammonium hydroxide, and the radiation dose in the product of sol-gel synthesis. The product of the synthesis was analyzed by scanning electron microscopy, x-ray diffraction of the product (after firing the pseudoboehmite at different temperatures), and it was also analyzed the temperature of endothermic and exothermic transformations using the thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC). The X-ray diffraction data show that α-alumina was obtained at 1100o C.

Sign in / Sign up

Export Citation Format

Share Document