共查询到20条相似文献,搜索用时 15 毫秒
1.
T. V. Kon’kova M. G. Gordienko M. B. Alekhina N. V. Men’shutina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(3):468-471
The high efficacy of iron-containing catalysts based on SiO2–Al2O3 systems obtained via sol–gel method in the oxidative destruction of carmoisine azo dye in aqueous solutions is demonstrated. It is found that the stability of the catalysts with respect to the leaching of iron ions into a solution during catalysis grows along with the aluminum content in the composition of aluminosilicate supports. It is concluded that the synthesized catalysts are promising materials for purifying wastewaters contaminated with organic dyes. 相似文献
2.
A. Kamyabi-Gol S. M. Zebarjad S. A. Sajjadi 《Journal of Sol-Gel Science and Technology》2009,51(1):92-101
The present work deals with the synthesis of Ni–SiO2–Al2O3 nanocomposites fabricated by embedding nickel oxide particles, obtained from hexahydrated nickel nitrate [Ni(NO3)2 · 6H2O], in matrixes with different molar percents of Silica/Alumina, through sol–gel method based on hydrolysis and condensation
of tetraethylorthosilicate (TEOS) and Aluminum Isopropoxide [Al(OC3H7)3] alkoxides. Due to the various factors, e.g., pH, EtOH/TEOS/H2O ratio, Si/Ni ratio etc., influencing the nickel grain size of the nanocomposites, Taguchi robust design method of system
optimization was used to determine the percent of contribution (%ρ) of each factor. The nanocomposites were reduced in a flow
of hydrogen and nitrogen gas at 700 °C for half an hour. The nickel grain size in the nanocomposites was determined by utilizing
Scherrer`s method and XRD patterns. The smallest nickel grain size obtained from the Taguchi orthogonal array was about 24 nm,
later confirmed by TEM observations. After optimization of the controlling factors, a nickel grain size of 15.4 nm was obtained.
It was found that the SiO2/Al2O3 molar ratio of the matrix had the most influence on the nickel grain size (29.22%) and the Water/TEOS molar ratio stood in
second place (21.44%). It was illustrated that the starting temperature of the aluminum isopropoxide had the least influence
on the nickel grain size. 相似文献
3.
Alumina-based pigments were synthesized by the proteic sol–gel method. In this method, coconut water is employed as polymeric
agent instead of the conventional alkoxide precursors. To this study, three common chromophore metallic ions (Mn3+, Co3+, and Cr3+) were chosen in order to verify the method efficiency. Differential thermal analysis (DTA), thermogravimetry (TG), and XRD
techniques were used to characterize the synthesis process. The colorimetric characterization of the produced pigments was
done according to the CIE-L*a*b* 1976 norm which is recommended by the CIE (International Commission on Illumination). The
synthesized pigments presented intense and uniform colors in accordance to the literature results for each chromophore ion.
The produced pigments also presented agglomerated with an average grain size of 180 nm when calcined at 800 °C. 相似文献
4.
C. Aydın Sh. A. Mansour Z. A. Alahmed F. Yakuphanoglu 《Journal of Sol-Gel Science and Technology》2012,62(3):397-403
Pure and boron (B) doped iron oxide (Fe2O3) nanostructured thin films were prepared by sol–gel spin coating method. The effects of B (0.1, 0.2, 0.5 and 1 %) content
on the crystallinity and morphological properties of Fe2O3 films were investigated by X-ray diffractometer and atomic force microscopy. X-ray diffraction patterns revealed that the
Fe2O3 films have a rhombohedral crystalline phase of α-Fe2O3 phase (hematite) with nanostructure and their crystallite size (D) is changed from 27 ± 2 to 45 ± 5 nm with B dopant content.
The minimum crystallite size value of 27 ± 2 nm was obtained for 0.2 % B doped Fe2O3 film. Carrying out UV–VIS absorption study for both doped and undoped films at room temperature, it was realized that allowed
optical transitions may be direct or indirect transitions. The direct and indirect energy gap values for pure Fe2O3 were obtained to be 2.07 and 1.95 eV, respectively. The optical band gap value of the films was changed with 0.1 % B doping
to reach 1.86 eV for direct band gap and 1.66 eV in case of indirect band gap. 相似文献
5.
6.
Al2O3–TiO2 nanocrystalline powders were synthesized by sol–gel process. Aluminum sec-butoxide and titanium isopropoxide chemicals were
used as precursors and ethyl acetoacetate was used as chelating agent. Thermal and crystallization behaviors of the precursor
powders were investigated by thermal gravimetric-differential thermal analysis, Fourier-transform infrared spectrum and X-ray
diffraction. The average crystalline size of heat treated Al2O3–TiO2 powders at 1,100 °C is ~100 nm. 相似文献
7.
Aiju Zhang Zhihong Li Zicheng Li Yumei Zhu 《Journal of Sol-Gel Science and Technology》2009,49(1):6-11
SiO2–Al2O3–Na2O glass coated cubic boron nitride (cBN) abrasive particles were prepared by sol–gel technique. The results indicated that
SiO2–Al2O3–Na2O glass was excellent material for oxidation protection of cBN abrasive grains because coefficient of thermal expansion of
this glass closely matched that of cBN materials. The single particle compressive strength and impact toughness of this glass
coated cBN abrasive particles were significantly increased. For the application of glass coated cBN abrasives to vitrified
grinding wheels, it was evident that the glass coating provided high bonding strength between cBN abrasive grains and vitrified
bond system. 相似文献
8.
Ping Zhang Mingxia Xu Lan Liu Lingxia Li 《Journal of Sol-Gel Science and Technology》2009,50(3):267-270
A new red-emitting long afterglow Sr3Al2O6: Eu2+, Pr3+ phosphor was synthesized by sol–gel methods using Sr(NO3)2, Al(NO3)3·9H2O, Eu(NO3)3 and Pr(NO3)3 as raw materials. The crystalline structure of the phosphor powders were characterized by X-ray diffraction. Luminescent
properties of the phosphor powders were analyzed by the fluorescence spectrophotometer. Sr3Al2O6: Eu2+, Pr3+ phosphor powders with single Sr3Al2O6 phase were prepared at 1200 °C for 2 h in the reducing atmosphere. Pr3+ doped made the light intensity and the light-lasting time of Sr3Al2O6: Eu2+, Pr3+ phosphors improved. The emission peaks of the Sr3Al2O6: Eu2+, Pr3+ phosphor powders lay at 612 nm with the excitation of 472 nm and the longest afterglow time could last for about 15 min at
Pr3+ content of 0.06. 相似文献
9.
A series of Pd/Al2O3–ZrO2 materials have been prepared via sol gel method as an attractive route to obtain more homogeneous binary oxides Al2O3–ZrO2. A Zr loading between 2 and 15 wt% was used to investigate the Zr promotion of Pd/Al2O3 materials. The prepared catalysts were calcined at two different temperatures. Very interesting results have been obtained
at low zirconium content. A small amount of Zr is seen to be sufficient to stabilize the activity and to obtain good catalytic
performances with developed textural properties compared to conventional catalysts used to oxidize methane. The increase of
the zirconium loading is seen to decrease the catalytic activity may be due to the development of tetragonal zirconia phase
detected by XRD. Similar effect has been observed after heating catalysts at high temperatures. A loss in BET surface area
and in metal dispersion has been also observed for zirconium rich catalysts. A contradictory effect on textural and structural
properties is seen after their calcination at 700 °C. 相似文献
10.
M. Baikousi S. Agathopoulos I. Panagiotopoulos A. D. Georgoulis M. Louloudi M. A. Karakassides 《Journal of Sol-Gel Science and Technology》2008,47(1):95-101
Magnetic bioglasses in the system CaO–SiO2–P2O5 were prepared by interaction of acetic acid vapors with iron nitrate dispersed on the surface of sol–gel derived porous silicate
network. Upon pyrolysis, the created iron acetate species transform into magnetic iron oxide nanoparticles. X-ray diffraction
(XRD), FT-infrared (FT-IR) spectroscopy and surface area measurements (BET) were employed to monitor the evolution of glass
structural features during the synthetic pathway as well as the structure and the texture of the resultant glasses. XRD, Raman
spectroscopy and vibration magnetic measurements (VSM) revealed the features of magnetic phases, developed in the form of
γ-Fe2O3 and magnetite. The obtained glasses exhibit in vitro bioactivity, expressed by spontaneous formation of hydroxyapatite on
their surface after immersion in SBF at 37 °C, confirmed with μ-Raman and FT-IR spectroscopies. 相似文献
11.
Wen Wang Jian-Cun Rao Hua Ke Ming Feng Rui-Lin Xia Qing-Chang Meng De-Chang Jia Yu Zhou 《Journal of Sol-Gel Science and Technology》2010,56(1):87-92
We report the independent invention of perovskite ferroelectric nanowires strontium bismuth tantalate (SrBi2Ta2O9, SBT). Electrophoretic sol–gel techniques have been used successfully. The morphology and structures are analyzed via SEM,
TEM and XRD. SBT nanowires and nanoparticles filled template revealed 30 and 40 μm long, respectively. SBT are proved to be
a single phase of orthorhombic perovskite structure. As it indicated, SBT nanowires has been crystallized at 700 °C. To minimize
surface polarity, SBT nanowires oriented preferentially along the growing axis (c axis) by translation and rotation of atomic clusters of SBT. 相似文献
12.
13.
T. N. Afonasenko N. N. Leont’eva V. P. Talzi N. S. Smirnova G. G. Savel’eva A. V. Shilova P. G. Tsyrul’nikov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(10):1939-1945
The textural and structural properties of mixed oxides Ga2O3–Al2O3, obtained via impregnating γ-Al2O3 with a solution of Ga(NO3)3 and subsequent heat treatment, are studied. According to the results from X-ray powder diffraction, gallium ions are incorporated into the structure of aluminum oxide to form a solid solution of spinel-type γ-Ga2O3–Al2O3 up to a Ga2O3 content of 50 wt % of the total weight of the sample, accompanied by a reduction in the specific surface area, volume, and average pore diameter. It is concluded that when the Ga2O3 content exceeds 50 wt %, the β-Ga2O3 phase is observed along with γ-Ga2O3–Al2O3 solid solution. 71Ga and 27Al NMR spectroscopy shows that gallium replaces aluminum atoms from the tetrahedral position to the octahedral coordination in the structure of γ-Ga2O3–Al2O3. 相似文献
14.
V. Yu. Pereyma P. P. Dik O. V. Klimov S. V. Budukva K. A. Leonova A. S. Noskov 《Russian Journal of Applied Chemistry》2015,88(12):1969-1975
Supported nickel–molybdenum and nickel–tungsten hydrocracking catalysts prepared using a support that consists of 70% Al2O3 and 30% amorphous aluminosilicate were characterized by nitrogen and mercury porosimetry, IR spectroscopy of adsorbed CO, and high-resolution electron microscopy. The catalytic tests in hydrocracking of vacuum gas oil containing 3.39% sulfur showed that the nature of the hydrogenating component (NiMo or NiW) only slightly influences the vacuum gas oil conversion and the diesel fraction yield, but noticeable influences the properties of the diesel fraction obtained. The catalyst NiMo/Al2O3–amorphous aluminosilicates, compared to NiW/Al2O3–amorphous aluminosilicates, ensures lower sulfur content in the diesel fraction obtained, whereas the catalyst NiW/Al2O3–amorphous aluminosilicates allows obtaining a diesel fraction with lower content of polyaromatic compounds. 相似文献
15.
Yu. E. Lebedeva N. V. Popovich L. A. Orlova A. S. Chainikova O. Yu. Sorokin M. L. Vaganova D. V. Grashchenkov 《Russian Journal of Inorganic Chemistry》2017,62(8):1032-1037
The effects caused by modifying additives, namely nonionic surfactants (Tween 80 and Neonol AF 9-6) and oxides (B2O3 and HfO2), on the rheology, film formation, and phase formation in the yttrium aluminum silicate system prepared by sol–gel technology were studied. The effect of 1 wt % HfO2 additions on the activation energy of crystallization was studied. 相似文献
16.
Monica Ari Kimberly J. Miller Bojan A. Marinkovic Paula M. Jardim Roberto de Avillez Fernando Rizzo Mary Anne White 《Journal of Sol-Gel Science and Technology》2011,58(1):121-125
Aluminum molybdate was successfully synthesized using a simplified PVA assisted sol–gel method resulting in highly crystalline,
monophasic (monoclinic P21/a) samples. These materials could readily be obtained at temperatures of 600 and 700 °C after calcining for as little as
15–20 min. Scanning electron microscopy and X-ray powder diffraction indicated that even the sample calcined at 600 °C for
20 min was free of impurities and composed of submicron sized particles (~300 nm). Transmission electron microscopy was used
to confirm the monophasic character and submicron dimensions of the as-prepared powders. In addition to producing high quality
samples, it was also observed that the metal to PVA ratio used during this simplified synthesis, could be used as a control
parameter for tailoring the particle sizes of the final product. 相似文献
17.
A. I. Klyndyuk E. A. Tugova O. N. Karpov E. A. Chizhova M. V. Tomkovich V. M. Kononovich 《Russian Journal of General Chemistry》2016,86(10):2282-2287
The sequence of phases appearance during the formation of Bi1–xNdxFeO3 solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO3 or NdFeO3) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi1–xNdxFeO3 as the final product, due to the prevalence of various interphase contacts in the starting reaction zone. 相似文献
18.
E. A. Tugova 《Russian Journal of General Chemistry》2016,86(11):2410-2417
Regularities of formation of complex aluminates with structure of P/RS intergrowth type phases in the Ln2O3–MO–Al2O3 systems (Ln = rare-earth element, M = Mg, Ca, Sr, Ba) have been considered. Systematization of the data on formation of complex compounds coexisting with one-layer phases in the Ln2O3–MO–Al2O3 systems and analysis of geometry criteria of LnMAlO4 stability is a promising approach to prediction of novel compounds with structure of Ruddlesden–Popper phase. 相似文献
19.
Petr Brázda Daniel Nižňanský Jean-Luc Rehspringer Jana Poltierová Vejpravová 《Journal of Sol-Gel Science and Technology》2009,51(1):78-83
ε-Fe2O3/SiO2 nanocomposite was prepared by novel solgel method using single precursor for both nanoparticles and matrix. This method allows to prepare the samples free of α-Fe2O3 with 40% of Fe2O3 in SiO2. Nanoparticles of 12 nm diameter were obtained by annealing at 1,000 °C. The samples were characterized by powder X-ray diffraction and transmission electron microscopy. Mössbauer spectroscopy identified ε-Fe2O3 as the only magnetically ordered phase at room temperature. Magnetic measurements revealed progressive necking of hysteresis loops measured at 300 and 2 K. In both cases the intrinsic coercivity reaches only 0.25 T. Measurements up to 14 T shows monotonous decreasing trend of saturated magnetization with increasing temperature. 相似文献
20.
The purpose of this work was to employ the differential thermal analysis (DTA) technique to compare variations in the collapse
energy of the zeolite Y crystalline structure in a fresh catalyst and in the same catalyst impregnated with nickel and vanadium.
A small exothermic signal in the DTA curve at 950–1150 °C indicated the collapse of the crystalline structure. The areas of
the exothermic signals in the DTA curves of the two samples indicated a reduction in the curve of the metal impregnated catalyst.
These results were compared with X-ray data, leading to the conclusion that metal impregnation affects the zeolite Y crystalline
structure and that the DTA technique is a potentially useful tool for measuring the integrity of zeolite Y in catalysts. 相似文献