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1.
Synthetic spinels of the system MgO-Cr2O3-Al2O3-Fe2O3 are considered and the desirability of organizing their production for the refractory industry is demonstrated.
Translated from Novye Ogneupory, No. 6, pp. 32–35, June 2008. 相似文献
2.
Nanoporous silica membrane without any pinholes and cracks was synthesized by organic templating method. The tetrapropylammoniumbromide
(TPABr)-templating silica sols were coated on tubular alumina composite support ( γ-Al2O3/ α-Al2O3 composite) by dip coating and then heat-treated at 550 °C. By using the prepared TPABr templating silica/alumina composite
membrane, adsorption and membrane transport experiments were performed on the CO2/N2, CO2/H2 and CH4/H2 systems. Adsorption and permeation by using single gas and binary mixtures were measured in order to examine the transport
mechanism in the membrane. In the single gas systems, adsorption characteristics on the α-Al2O3 support and nanoporous unsupport (TPABr templating SiO2/ γ-Al2O3 composite layer without α-Al2O3 support) were investigated at 20–40 °C conditions and 0.0–1.0 atm pressure range. The experimental adsorption equilibrium
was well fitted with Langmuir or/and Langmuir-Freundlich isotherm models. The α-Al2O3 support had a little adsorption capacity compared to the unsupport which had relatively larger adsorption capacity for CO2 and CH4. While the adsorption rates in the unsupport showed in the order of H2> CO2> N2> CH4 at low pressure range, the permeate flux in the membrane was in the order of H2≫N2> CH4> CO2. Separation properties of the unsupport could be confirmed by the separation experiments of adsorbable/non-adsorbable mixed
gases, such as CO2/H2 and CH4/H2 systems. Although light and non-adsorbable molecules, such as H2, showed the highest permeation in the single gas permeate experiments, heavier and strongly adsorbable molecules, such as
CO2 and CH4, showed a higher separation factor (CO2/H2=5-7, CH4/H2=4-9). These results might be caused by the surface diffusion or/and blocking effects of adsorbed molecules in the unsupport.
And these results could be explained by surface diffusion.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
3.
N. V. Lebukhova V. S. Rudnev P. G. Chigrin K. S. Makarevich I. B. Lukiyanchuk N. F. Karpovich 《Catalysis in Industry》2011,3(3):294-300
Two methods were used to obtain a catalytically active oxide coating on the surface of titanium for the catalytic afterburning
of diesel soot: plasma electrochemical formation of an oxide film on the surface of titanium and extraction pyrolytic deposition
of the Li2Cu2(MoO4)3 compound. The Li2Cu2(MoO4)3/TiO2 + SiO2/Ti compositions synthesized by the single-step extraction pyrolytic treatment of the oxidized surface of titanium ensured
a high burning rate of soot of ∼300°C. The subsequent deposition of Li2Cu2(MoO4)3 lowers the activity of the catalyst, due probably to the growth of molybdate phase crystallites and the filling of open oxide
film pores. Double lithium-copper molybdate is able to reduce appreciably the concentration of CO in the oxidation products
of soot. The advantages of these methods are the possibility of forming high-cohesion durable coatings on surfaces of any
complexity, the simplicity of their implementation, and high productivity and low cost. The obtained results can be recommended
for use in developing methods for creating composite coatings on catalytic soot filters. 相似文献
4.
V. P. Danilov E. A. Frolova D. F. Kondakov L. I. Avdyushkina V. T. Orlova 《Theoretical Foundations of Chemical Engineering》2011,45(5):697-701
The polytherms of ice melting in sections of the Ca(NO3)2-Mg(NO3)2-CO(NH2)2-H2O system with different component ratios were studied in the temperature interval from 0 to −40°C. A series of nitrate and
nitrate-carbonate reagents that are promising for the creation of anti-acing reagents were found, which form eutectics with
ice at temperatures from −25 to −39°C. Their properties, viz., melting properties with respect to ice and corrosiveness on
metals and alloys, were determined. An effective corrosion inhibitor was selected. 相似文献
5.
A new compound of (Rb,K)2Cu3(P2O7)2 is obtained by high-temperature reactions from a mixture of RbNO3, KNO3, Cu(NO3)2, and (NH4)4P2O7. The crystal structure was solved by direct methods and refined to R 1 = 0.056 for 5022 independent reflections. The compound belongs to a rhombic crystal system, P212121, Z = 8, a = 9.9410(7) Å, b = 13.4754(6) Å, c = 18.6353 (3) Å, and R = 0.056. The basis of the structure is a complex copper-phosphate skeleton of the composition of [Cu3(P2O7)2]2–, which can be regarded as consisting of two types of heteropolyhedral layers parallel to the (001) plane. The layers are alternated with each other, forming a frame, in the cavities of which the positions of alkali cations are located, statistically populated with K+ and Rb+ ions. Based on the refined populations of the positions of alkali cations, an exact chemical formula of the compound can be written as Rb1.28K0.72Cu3(P2O7)2. The compound is the most complex among those known to this day of the composition of A2 IB3 II(P2O7)2 (A = Li, Na, K, Rb, or Cs; B = Ni, Cu, or Zn). 相似文献
6.
7.
Cerium oxide is one of the most important rare earth elements that is introduced into glass compositions due to its great effects on the optical properties. CeO2 was introduced in Hench’s patented SiO2-Na2O-CaO-P2O5 glasses with different concentrations in order to study its effect on the optical behavior of this glass including optical band gap, transmittance, reflectance and refractive index and to give a complete view for the optical properties on cerium oxide-doped silicate glasses. 相似文献
8.
Jingfu Wang Yan Wang 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(4):913-918
In the present study, the crystallization behavior and thermal stability of amorphous Zr55Cu20Ni10Al10Ti5 alloy, obtained by melt-spinning, have been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA)
and transmission electron microscopy (TEM). The activation energy for crystallization has been evaluated by the Kissinger
method, and it has been found that E
x obtained from the crystallization onset temperature (T
x) is lower than E
p determined by the crystallization peak temperature (T
P). During the continuous annealing process, ZrO and h-Al3Zr5 phases firstly precipitate from the amorphous matrix, then Zr2Ni0.66O0.33 phase forms continuously and its relative content increases with increasing annealing temperature. However, no crystalline
phases have been observed during the isothermal annealing process at 733 K (below T
x) for 90 min. The atomic clusters can keep the stability state through adjusting the short-range ordering. 相似文献
9.
The thermal behavior of natural borosilicate howlite, Ca2B5SiO9(OH)5, is studied by the methods of high-temperature X-ray diffraction and differential thermal analysis in the temperature range of 30–1100°C. The thermal expansion is anisotropic (αmax/αmin = 3.6); the degree of anisotropy increases (αmax/αmin = 4.3) with a temperature increase up to 480°C (360–480°C). 相似文献
10.
The results of studying the thermal behavior of natural boron albite–reedmergnerite NaBSi3O8 and aqueous boricilicate–searlesite NaBSi2O5(OH)2 obtained by the method of hydrothermal synthesis are presented. In the investigated temperature range, reedmergnerite (30–780°C) does not undergo phase transformations. Thermal expansion is sharply anisotropic, which is a characteristic feature of the expansion of feldspars. Aqueous borosilicate searlesite (25–750°C) is amorphized above 400°C as a result of dehydration and cristobalite crystallizes from the amorphous phase. The expansion of searlesite is relatively isotropic. 相似文献
11.
Yu. K. Startsev A. A. Pronkin I. A. Sokolov I. V. Murin 《Glass Physics and Chemistry》2011,37(3):263-282
The glasses, in which oxygen was partially replaced with sulfur, have been synthesized in the Na2O-P2O5-Na2S system. The chemical and chromatographic analyses of the glasses synthesized have been performed. The temperature-concentration
dependences of electrical conductivity of the glasses have been studied over a wide temperature range; the glass transition
temperatures and the nature of charge carriers have been determined. The IR spectra and Raman spectra have been recorded at
room temperature; the density and microhardness of the glasses and ultrasound velocity have been measured. A comparison of
the electrical conductivities of the investigated glasses with those of the earlier studied glasses in the Na2O-P2O5 system has shown their fair coincidence. The introduction of sodium sulfide into the Na2O-P2O5 system is accompanied by an approximately threefold increase in electrical conductivity, although the concentrations of charge
carriers (sodium ions) in the glasses amount to ∼17 and ∼26 mmol/cm3, respectively. The rise in electrical conductivity has been assumed to be caused by the increase in the degree of dissociation
of polar structural chemical units including sulfide ions and by the higher mobility of sodium ions in the oxygen-free matrix. 相似文献
12.
The crystal structure of a low-temperature modification of the Li12Zn4(P2O7)5 compound has been determined by full-profile analysis from the X-ray powder diffraction data. The compound crystallizes in the monoclinic crystal system (a = 5.130(1) Å, b = 13.454(1) Å, c = 8.205(1) Å, β = 90.36(1)°, space group P21/n, Z = 4) and has a framework structure in which the zinc and lithium atoms statistically occupy equivalent positions. 相似文献
13.
Pharatree Jaita Anucha Watcharapasorn Sukanda Jiansirisomboon 《Nanoscale research letters》2012,7(1):24
Lead-free piezoelectric compositions of the (1-x)Bi0.5(Na0.40K0.10)TiO3-x(Ba0.7Sr0.3)TiO3 system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050°C and
1,175°C for 2 h. The effect of (Ba0.7Sr0.3)TiO3 [BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was
1,125°C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that
showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain
size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the
BNKT ceramic. A large room-temperature dielectric constant, ε
r
(1,609), and piezoelectric coefficient, d
33 (214 pC/N), were obtained at an optimal composition of x = 0.10. 相似文献
14.
C. Sepulveda R. Garcia N. Escalona D. Laurenti L. Massin M. Vrinat 《Catalysis Letters》2011,141(7):987-995
Abstract
Rhenium sulfide based catalysts were prepared by the incipient wetness impregnation method over alumina and silica supports and evaluated for 4,6-dimethyldibenzothiophene hydrodesulfurization in a high-pressure stirred-tank reactor. The catalyst prepared over silica was about six times more active for hydrodesulfurization than the corresponding catalyst prepared over alumina and a NiMo/Al2O3 industrial reference catalyst. This surprising and positive SiO2 support effect was explained by a metallic character of the supported sulfide, which was demonstrated using a kinetic approach of competitive hydrogenations and by XPS characterization. 相似文献15.
I. A. Zvereva V. F. Popova E. A. Tugova N. S. Pylkina V. V. Gusarov 《Glass Physics and Chemistry》2005,31(6):808-811
The phase equilibria are investigated and the phase diagram is constructed for the Gd2O3-SrAl2O4 pseudobinary join of the Gd2O3-SrO-Al2O3 ternary oxide system. One ternary compound, namely, Gd2SrAl2O7, is revealed in the Gd2O3-SrAl2O4 join. It is found that this compound undergoes congruent melting. 相似文献
16.
17.
Junyeong Kim Jeong Yeon Do No-Kuk Park Seung Jong Lee Jin-Pyo Hong Misook Kang 《Korean Journal of Chemical Engineering》2018,35(5):1089-1098
Nano-sized bismuth sulfide (Bi2S3) and titanium dioxide (TiO2) with the orthorhombic and anatase tetragonal structures, respectively, were synthesized for application as catalysts for the reduction of carbon dioxide (CO2) to methane (CH4). Four double-layered dense films were fabricated with different coating sequences—TiO2 (bottom layer)/Bi2S3 (top layer), Bi2S3/TiO2, TiO2/Bi2S3: TiO2 (1 : 1) mix, and Bi2S3: TiO2 (1 : 1) mix/Bi2S3: TiO2 (1 : 1) mix—and applied to the photoreduction of CO2 to CH4; the catalytic activity of the fabricated films was compared to that of the pure TiO2/TiO2 and Bi2S3/Bi2S3 doubled-layered films. The TiO2/Bi2S3 double-layered film exhibited superior photocatalytic behavior, and higher CH4 production was obtained with the TiO2/Bi2S3 double-layered film than with the other films. A model of the mechanism underlying the enhanced photoactivity of the TiO2/Bi2S3 double-layered film was proposed, and it was attributed in effective charge separation. 相似文献
18.
Structure and crystalline behavior of the ternary system ZnO-B2O3-P2O5 glasses were investigated by means of X-ray diffraction (XRD) and infrared Raman spectra. The research showed that number
of the planar [BO3] units increases with the increase of B2O3 content. When the B2O3 content is above ≥10 mol %, the relative content of planar [BO3] units increases rapidly and causes weakening of the glass structure and decrease in the chemical stability. In the crystallized
glasses the predominant crystal phase Zn2P2O7 decreases with the increase of B2O3 content, while the crystal phase BPO4 increases with it, which cause the declining of chemical stability and the decrease of thermal coefficients of expansion. 相似文献
19.
Philomena Schlexer Hsin-Yi Tiffany Chen Gianfranco Pacchioni 《Catalysis Letters》2017,147(8):1871-1881