共查询到20条相似文献,搜索用时 15 毫秒
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Chun-guang Gao Yong-xiang Zhao Yin Zhang Dian-sheng Liu 《Journal of Sol-Gel Science and Technology》2007,44(2):145-151
The Ni/ZrO2/SiO2 aerogels catalysts were synthesized via three different routes: (i) impregnation ZrO2–SiO2 composite aerogels with a aqueous solution of Ni(NO3)2, (ii) impregnation SiO2 aerogels with a mixed aqueous solution of Ni(NO3)2 and ZrO(NO3)2 · 2H2O, (iii) one-pot sol–gel procedure from precursors Ni(NO3)2/ZrO(NO3)2 · 2H2O/Si(OC2H5)4. These catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), ammonia temperature-programmed
desorption (NH3-TPD), N2 adsorption–desorption isotherms and Fourier transform infrared (FT-IR). The Liquid-phase hydrogenation of maleic anhydride
(MA) was performed over these catalysts. The results revealed that the different preparation routes result in a difference
between the obtained samples, concerning the crystal structure and composition, surface acidity, mixed level of each component,
texture, and catalytic selectivity. 相似文献
3.
M. G. Demidova N. O. Shaparenko T. Yu. Podlipskaya A. I. Bulavchenko 《Russian Journal of Inorganic Chemistry》2017,62(6):715-722
Stable SiO2 and TiO2 organosols were prepared by hydrolyzing tetraethyl orthosilicate (TEOS) in the presence of 6–12 M NH3 and titanium(IV) isopropylate (TTIP) in reverse microemulsions of 0.12–0.25 M bis(2-ethylhexyl) sulfosuccinate (Aerosol OT, AOT) in n-decane with the aqueous pseudophase content of 2–3 vol %, 0.018–0.090 M TEOS, and 0.15–0.55 vol %, 0.003–0.025 M TTIP. The degree of hydrolysis was monitored by IR spectroscopy (for TEOS) and spectrophotometry (for TTIP). Oxide nanoparticles were characterized by photon-correlation spectroscopy (PCS) (D h = 8–100 nm) and laser electrophoresis (ζ-potential = 7.4–11.6 mV). The occurrence of surface potential made it possible to separate the oxides from the excess of surfactant by nonaqueous electrophoresis and to determine particle sizes (7–40 nm) by means of transmission electron microscopy (TEM). 相似文献
4.
Mariusz Walkowiak Monika Osińska Teofil Jesionowski Katarzyna Siwińska-Stefańska 《Central European Journal of Chemistry》2010,8(6):1311-1317
This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes.
Hybrid TiO2-SiO2 ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating
agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion
batteries based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF/HFP) copolymeric membranes. The powders, dry membranes
and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte
uptake and electrochemical characteristics in Li-ion cells. 相似文献
5.
Li Chen Haixia Shen Zhen Lu Cang Feng Su Chen Yanru Wang 《Colloid and polymer science》2007,285(13):1515-1520
TiO2–SiO2 composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO2–SiO2 composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO2–SiO2) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO2–SiO2 composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO2–SiO2 composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO2–SiO2 core surface via surface functionalized reaction. The particle size of TiO2–SiO2 composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and
Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid
films. The average particle size of the TiO2–SiO2 composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO2–SiO2 composite nanoparticles are well dispersed in the PU matrix. 相似文献
6.
Fairouz Ghariani Radouanne Fezei Ahmed Hichem Hamzaoui 《Journal of Sol-Gel Science and Technology》2018,88(1):100-104
This paper reports a successful preparation of a pure forsterite Mg2SiO4 using the sol–gel approach and its application for the removal of impurities from a Tunisian frying oil. Magnesium nitrate hexahydrate and tetraethylortho-silicate were used as magnesium and silicon precursors, respectively. The synthesis was held at different calcination temperatures for 30?min. The annealed samples were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, and laser diffraction. The results revealed that the sample calcined at 500?°C was forsterite with unimodal particle size distribution (PSD) centered at 122.8?±?0.3?μm. The dispersion index I (indicator of particle size uniformity) was 1.84. With the temperature increase, well crystallized compounds were obtained. Their PSDs remain unimodal and shift towards smaller particles. A decrease of the dispersion index was also noted, indicating the formation of Mg2SiO4 with more uniform particle size. This study showed that 900?°C could be selected as energy saving temperature suitable for the preparation of a pure and well crystallized Mg2SiO4 within just 30?min of annealing time. The obtained silicate exhibited promoting results for the purification of waste frying oils. 相似文献
7.
Uraiwan Sirimahachai Nicholas Ndiege Ramesh Chandrasekharan Sumpun Wongnawa Mark A. Shannon 《Journal of Sol-Gel Science and Technology》2010,56(1):53-60
Nanosized TiO2 and nano-anatase TiO2 decorated on SiO2 spherical core shells were synthesized by using a sol–gel method. The synthesized pure TiO2 nano particle and TiO2 grafted on SiO2 sphere with various ratios have been characterized for their structure and morphologies by X-ray diffraction (XRD), X-ray
photoelectron spectroscopy (XPS), Fourier transform infrared spectrophotometry (FTIR) and transmission electron microscopy
(TEM). Their surface areas were measured using the BET method. The photocatalytic activity of all nanocomposites was investigated
using methylene blue as a model pollutant. The synthesized TiO2/SiO2 particles appeared to be more efficient in the degradation of methylene blue pollutant, as compared to pure TiO2 particles. 相似文献
8.
V. H. Martínez-Landeros Bruce E. Gnade M. A. Quevedo-López R. Ramírez-Bon 《Journal of Sol-Gel Science and Technology》2011,59(2):345-351
In this work we report the performance of permeation barriers based on organic/inorganic multilayer stacks. We have used PMMA-SiO2 (poly methyl methacrylate-silica) hybrid films synthesized through a sol–gel route as organic–inorganic components, whereas
Al2O3 thin films were used as the inorganic component. The hybrid layers were deposited by dip coating and the Al2O3 by atomic layer deposition (ALD), films were prepared on polyethylene naphthalene (PEN) substrates. The permeability of the
films and stacks is evaluated using helium as the diffusion gas in a custom made ultra-high vacuum system. The results show
that permeability for PEN is reduced from 5 × 10−3 g/m2-day to about 9 × 10−5 g/m2-day for the best multiple barrier evaluated. Increased barrier properties are due to the increasing in the path and hence
the lag-time of the permeating gas. In particular, we report the surface roughness of the different layers and its impact
on the barrier performance. The hybrid layers reduced notably the roughness of the bare PEN substrate improving the quality
of the Al2O3 layer in the barrier. The optical transmittance of the barriers in the visible region is higher than 80% in all the studied
cases. 相似文献
9.
Nanostructures TiO2–SiO2 photocatalysts were successfully synthesized using the sol-gel method, hydro-calcination, co-precipitation and room-temperature solid-phase synthesis technology. X-ray powder diffraction pattern (XRD), Fourier transform infrared spectrum (FTIR), photoluminescence (PL) spectra, thermal analyses (TG–DTA), scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) were used to characterize the as-synthesized catalysts. Photocatalytic performances of the catalysts were evaluated by the degradation of methyl orange (MO) under s imulated natural light and the degradation rate of MO is 97.2%. The composites showed a good stability: after five recycling runs there are no significant decreases in the photocatalytic activity. The photodegradation of methylene blue, rhodamine B, methyl violet, naphthol green B, basic fuchsin, malachite green, and methyl red were also tested, and the degradation rate of dyes could reach over 94.2 %. A possible mechanism for the photocatalysis with the TiO2–SiO2 was proposed. 相似文献
10.
Ultra-long and uniform CuAlO2 nanowires were successfully synthesized within a porous anodic aluminum oxide template by means of sol–gel method at 900 °C.
The results of X-Ray diffraction indicate that the obtained CuAlO2 nanowires have a single delafossite structure. The scanning electron microscopy and transmission electron microscopy show
that the CuAlO2 nanowires have a uniform diameter with about 50 nm and a length up to 10 μm. Room-temperature photoluminescence measurement
of nanowires exhibits an ultraviolet near-band-edge emission around 350 nm (3.54 eV). 相似文献
11.
S. A. Kirillova V. I. Almjashev V. V. Gusarov 《Russian Journal of Inorganic Chemistry》2011,56(9):1464-1471
Phase equilibria in a miscibility gap of the SiO2-TiO2 system were studied. A visual polythermal analysis and annealing of samples were performed in a Galakhov microfurnace. The
microstructure and composition of the obtained samples were investigated by scanning electron microscopy and electron probe
microanalysis. A critical analysis of the experimental data was made. Thermodynamically optimized based on the sub-regular
solution model, a phase diagram of the SiO2-TiO2 system was constructed. 相似文献
12.
Processes involved in the preparation of zirconia and yttria thin films by sol-gel technology from film-forming solutions (FFSs) were studied over the entire range of concentrations. The physicochemical properties, composition, and structure of the films were studied. 相似文献
13.
Jinhe Sun Yongzhong Jia Yan Jing Ying Yao Wu Li 《Russian Journal of Inorganic Chemistry》2008,53(1):36-39
Cu(OH)2 nanowires with a diameter of 8–10 nm and lengths of tens of micrometers were fabricated in the basic solution by dropping
simply NaOH solution into CuCl2 solution at ambient temperature. The formation mechanism of nanowires was discussed. Scanning electron microscopy (SEM),
transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the samples.
This article was submitted by the authors in English. 相似文献
14.
D. Yu. Ebert A. S. Savel’eva N. V. Dorofeeva O. V. Vodyankina 《Kinetics and Catalysis》2017,58(6):720-725
FePО4/SiO2 supported catalysts with a different content of iron phosphate are prepared. The properties of the catalyst are changed by the introduction of alkali metal compounds (Na or Cs) on its surface. The samples obtained are characterized by X-ray diffraction, low-temperature nitrogen adsorption, temperatureprogrammed reduction by hydrogen, and temperature-programmed desorption of ammonia. The catalytic properties are investigated in the reaction of gas-phase propylene glycol oxidation. It is shown that the selectivity of methylglyoxal formation on the unmodified catalysts is determined by the state of the supported active component and by its reduction–oxidation ability under the action of a reaction mixture. 相似文献
15.
Silica and core–shell structured titania/silica (TiO2/SiO2) nanoparticles with particles size ranging from tens to hundreds of nanometers were prepared and deposited onto cotton fabric
substrates by sol–gel process. The morphologies of the nanoparticles were characterized by field-emission scanning electron
microscope (FE-SEM). The photocatalytic decomposition properties as well as UV-blocking properties of the fabrics treated
with SiO2 and TiO2/SiO2 nanoparticles were investigated. 相似文献
16.
A. V. Petrov I. V. Murin A. K. Ivanov-Schitz 《Russian Journal of General Chemistry》2017,87(7):1456-1460
Electronic structure of (SiO2)3 clusters was calculated by the density functional method. Charge states were determined using various functionals, bond lengths and total energies of clusters were estimated. 相似文献
17.
E. Yu. Safronova I. A. Stenina A. B. Yaroslavtsev 《Russian Journal of Inorganic Chemistry》2010,55(1):13-17
Composites based on MF-4K perfluorinated cation-exchange membranes doped with hydrous silica nanoparticles, which were precipitated
under various conditions, and with tungstophosphoric heteropolyacid nanoparticles were synthesized. The proton conductivity
of the composites was studied as a function of temperature and relative ambient humidity. As a result of modification, the
water content and ion conductivity of the membranes in low humidities increase by 2.5 orders of magnitude compared to unmodified
MF-4SK membranes and the material is rendered less water-dependent. 相似文献
18.
Yu. V. Mikushina A. B. Shishmakov V. V. Matskevich N. A. Zhuravlev O. V. Koryakova V. G. Kharchuk L. A. Petrov 《Russian Journal of Inorganic Chemistry》2008,53(10):1557-1560
Silica/titania binary xerogels were prepared by joint hydrolysis of the ingredients. Gels of various compositions were characterized by 1H NMR spectroscopy, IR spectroscopy, and thermogravimetry. The spectral characteristics of binary systems differ considerably from mere superposition of the spectra of the two constituent compounds and the spectrum of a mechanical mixture. A feasibility was demonstrated for controlling the acid properties of binary oxide gels via varying the component mole ratio. 相似文献
19.
Omar G. Morales-Saavedra Ernesto Rivera José O. Flores-Flores Rosalba Castañeda José G. Bañuelos José M. Saniger 《Journal of Sol-Gel Science and Technology》2007,41(3):277-289
The synthesis of sol-gel materials induced by ultrasonic irradiation (sonolysis) is implemented as an alternative method for
the fabrication of highly pure organic-inorganic composites with good monolithic, mechanical and optical properties. Ultrasonic
irradiation, instead of commonly used basic- or acidic-catalyst was used to produce acoustical cavitation within the liquid
H2O/tetraethyl-ortosilicate (TEOS) reactants. This procedure forms a hydrolyzed-TEOS colloidal dispersion (sol) which produces,
after drying, a highly pure SiO2 network. The resulting SiO2 glass exhibits high porosity and allows the inclusion of several organic compounds in the colloidal sol-state. Novel, optical
active synthesized liquid crystalline (LC)-azo-compounds, bent shaped mesogens, cis- and trans-poly(1-ethynylpyrene)s, as well as fullerene (C60) spheres and classical organic dyes were successfully incorporated as dopant agents within the novel catalyst free (CF) SiO2-sonogel host matrix. Absorption and fluorescence spectroscopy studies were carried out in order to characterize the optical
performance of both the CF-sonogel and several hybrid composites The pulsed laser photoacoustic technique (LPAT) was implemented
to determine thermodynamic phase transitions of LC-based hybrids and laser induced damage (photo-degradation) in dye-based
composites. Finally, comparative morphology studies between undoped reference samples and some doped composites were performed
by Atomic Force Microscopy (AFM), where an optimal TEOS/dopant concentration ratio, to obtain good mechanical properties among
the studied samples, has been found. 相似文献
20.
L. Li X. Wang J. Shen L. Zhou T. Zhang 《Journal of Thermal Analysis and Calorimetry》2005,82(1):103-107
Adsorption microcalorimetry has been employed to study the interaction of ethylene with the reduced and oxidized Pt-Ag/SiO2catalysts with different Ag contents to elucidate the modified effect of Ag towards the hydrocarbon processing on platinum
catalysts. In addition, microcalorimetric adsorption of H2, O2, CO and FTIR of CO adsorption were conducted to investigate the influence of Ag on the surface structure of Pt catalyst.
It is found from the microcalorimetric results of H2and O2adsorption that the addition of Ag to Pt/SiO2leads to the enrichment of Ag on the catalyst surface which decreases the size of Pt surface ensembles of Pt-Ag/SiO2catalysts. The microcalorimetry and FTIR of CO adsorption indicates that there still exist sites for linear and bridged CO
adsorption on the surface of platinum catalysts simultaneously although Ag was incorporated into Pt/SiO2. The ethylene microcalorimetric results show that the decrease of ensemble size of Pt surface sites suppresses the formation
of dissociative species (ethylidyne) upon the chemisorption of C2H4on Pt-Ag/SiO2. The differential heat vs. uptake plots for C2H4adsorption on the oxygen-preadsorbed Pt/SiO2and Pt-Ag/SiO2catalysts suggest that the incorporation of Ag to Pt/SiO2could decrease the ability for the oxidation of C2H4. 相似文献