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1.
An oxygen-diluted partially premixed/oxygen-enriched supplemental combustion (ODPP/OESC) counterflow flame is studied in this paper. Flame images are obtained through experiments and numerical simulations with the GRI-Mech 3.0 chemistry. The oxygen dilution effects are revealed by comparing the flame structures and emissions with those of a premixed flame and partially premixed flame (PPF) at the same equivalence ratio (?Σ = 0.95 and ? f = 1.4). The results show that both PPF and ODPP/OESC flames have distinct double flame structures; however, the location of the premixed combustion zone and the distance between premixed/nonpremixed combustion zone are significantly different for these two cases. For the ODPP/OESC flame, the temperature in the premixed combustion zone is lower and the premixed zone itself is located farther downstream from the fuel nozzle, which leads to reduction of NO and CO emissions, as compared to those of the PPF. Therefore, by adjusting the distribution of the oxygen concentration in the premixed and nonpremixed combustion zones, the ODPP/OESC can effectively balance the chemical reaction rate in the entire combustion zone and, consequently, reduce emissions. 相似文献
2.
The technology of liquid-phase synthesis of mesoporous xerogels and aerogels based on ZrO2–Y2O3–CeO2 is developed. Xerogels are obtained by the coprecipitation of hydroxides, while aerogels are obtained in accordance with the sol–gel technology: the average pore size is 1.5–17.2 nm and the specific surface area is 120–878 m2/g. Aerogels are characterized by a high degree of porosity: the pore volume attains 1–4 cm3/g. Based on precursor xerogels, nanopowders of a tetragonal solid solution of the (ZrО2)0.92(Y2О3)0.03(CeО2)0.05 composition with a particle size of 5–9 nm and S spec = 74 m2/g were fabricated. Due to the high values of their specific surface area, the synthesized xerogels and aerogels are promising as sorbents, catalysts, or catalyst supports. 相似文献
3.
Idris Kabalci Erkan Koc Sirri Semih Ozturk 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(3):788-794
Oxide based optical glass materials has important potential material in many applications from fiber optic to sensor due to the high transparency and amourphous structures. The objective of this study is to synthesize the novel optical glass materials based on the bismuth and aluminum contents to be able to determine the physical, chemical and mechanical properties by considering the systematic experimental steps. In this study, Bi2O3–Al2O3 based tellurite optical glasses have been prepared by using conventional melt quenching method as a function of the both Bi2O3 and Al2O3 compositions. There is a strong interactions between the glass former and modifier ions that might effect on the structure and mechanical properties. During the experimental steps, thermal, structural and mechanical properties of the prepared glass materials have been determined considering the DTA/DSC, FT-IR spectroscopy, SEM and Vicker’s hardness techniques, respectively. Thermal parameters, like glass transition, Tg, onset, Tx, crystallization, Tp, and melting, Tm, temperatures were obtained by using DTA scan. 相似文献
4.
Vitrification in the Ga2S3–GeS2–PbF2 system is considered. The physicochemical properties of glasses, such as density, microhardness, electroconductivity, refraction index, and transmission percentage of specimens in visible and IR ranges of spectrum are studied; differential thermal analysis is carried out; and Raman and electron paramagnetic resonance spectra are investigated. 相似文献
5.
Xiaole Jiang Xingzheng Liu Qianqian Chen Risheng Jin Yu Lu Jingxiong Yu Ying Wu Yiming He 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(6):1683-1693
Ag2WO4/g-C3N4 composites with different Ag2WO4 concentration and calcination temperature were synthesized via a mixing and heating approach. Various techniques were used to investigate the characters of the as-prepared samples, such as thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy. The degradation of rhodamine B (20 ppm) under visible light was performed to investigate the photocatalytic activity of Ag2WO4/g-C3N4 composites. Results indicate that the Ag2WO4/g-C3N4 is actually Ag/Ag2WO4/g-C3N4 ternary system. 7.5 wt% Ag2WO4/g-C3N4 prepared at 300 °C presented the best photocatalytic performance in rhodamine B degradation. The degradation rate reaches 0.0679 min?1, which is 3.25 times higher than the value of pure g-C3N4. The enhanced activity is attributed to the synergetic effect of Ag2WO4, g-C3N4 and metal Ag. Additionally, cycling experiments also proved that the Ag2WO4/g-C3N4 photocatalyst has good stability. 相似文献
6.
Najla Karaa Besma Hamdi Abderrazek Oueslati Abdelhamid Ben Salah Ridha Zouari 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(4):746-754
The ionic salt [2(C5H6N2Cl)+], [CuCl4]2? complex of copper(II) has been synthesized and characterized. The X-ray diffraction analysis with a single crystal of this compound showed that the title compound (4-amino-2-chloropyridinium)2CuCl4 [(CAP)2CuCl4], crystallized at room temperature in the monoclinic system, space group C2/c (N°.15) and the following : a = 16.0064 (2) Å; b = 7.7964 (10) Å; c = 14.7240 (2) Å; β = 102.497 (10)°; V = 1793.91 (4) Å3 and Z = 4. The structure was solved by using 1,589 independent reflections down to R value of 0.021. The unit cell is made up of tetrachlorocuprate(II) anions and 4-amino-2-chloropyridinium cations linked together by an extensive hydrogen bond network of types N–H···Cl (N: pyridinium) and N–H···Cl (N: amine), and cation-lone pair of nitrogen element interactions. Solid state NMR spectra showed one and five isotropic resonances, 63Cu and 13C, respectively, confirming the solid state structure determined by X-ray diffraction. Impedance spectroscopy study, reported for single crystal, revealed that the conduction in the material was due to a hopping process. This work aims to reveal the thermal properties of a new copper(II) based organic–inorganic hybrid and the conductivity properties that these compounds exhibit. 相似文献
7.
S. I. Niftaliev I. V. Kuznetsova M. V. Chislov L. V. Lygina I. A. Zvereva 《Glass Physics and Chemistry》2017,43(4):363-367
This work is devoted to the preparation of zirconium oxide nanopowders stabilized by lanthanum oxide using the method of codeposition in the presence of hydrogen peroxide. Nanopowders composed of 0.97ZrO2 · 0.03La2O3 with particles of 10–20 nm are obtained. It is found that in the temperature interval of 500–1100°C the tetragonal and monoclinic points of the zirconium oxide phase crystallize at the same time. 相似文献
8.
Effects of ZnO–B2O3 (ZB) addition on the densification, phase evolution and microwaves dielectric properties of Ba4Sm9.33Ti18O54 (BST) ceramics for low-temperature fired applications have been investigated. The sintering temperature of BST ceramics can be effectively lowered to about 1000°C with introduction of ZB. Tungsten bronze like single phase is observed in the BST ceramics with 0.5 and 1.0% ZB. However, Sm2Ti2O7 secondary phase appears when ZB addition reaches 2%, and Sm2Ti2O7 phase gradually increases with the increase ZB addition. Microwave dielectric properties of the present ceramics are strongly dependent on phase constitution and density. Optimal microwave dielectric properties of ε = 63.4, Qf = 2830 GHz, τ f =–8.8 ppm/°C is obtained for BST ceramics with 1% ZB addition. 相似文献
9.
D. B. Sable Pankaj P. Khirade Shankar D. Birajdar A. A. Pandit K. M. Jadhav 《Glass Physics and Chemistry》2017,43(4):302-312
The oxide glass system of the composition (10 – x)SrO–xFe2O3–90V2O5, (x = 0, 2, 4, 6 and 8 mol %) were prepared by a standard melt quenching technique. The amorphous nature of the prepared glass was confirmed using X-ray diffraction technique. The infrared spectra of these glasses were recorded over a continuous spectral range (850–1500 cm–1). The density of prepared sample was obtained by the Archimedes principle. The physical parameters of the glasses were also determined with respect to the composition. Density increases from 3.10 to 3.20 g/cm3, whereas the molar volume decreases with the increase in Fe2O3 concentration. In order to study optical properties, absorption spectra were measured at room temperature. Indirect optical energy band gap, optical dielectric constant, refractive index were calculated from optical energy band gap. The refractive index decreases gradually with the increase in Fe2O3 content due to increase of bridging oxygen’s. For temperatures from 300 to 500 K, the dc conductivity increased with the increasing Fe2O3 content. The dielectric properties like dielectric constant, dielectric loss factor and dielectric loss tangent investigated at the room temperature in the frequency range of 10 kHz to 1 MHz decreases with frequency. The dielectric behavior shows strong frequency as well as composition dependence. 相似文献
10.
E. A. Buluchevskii E. D. Fedorova A. V. Lavrenov M. V. Zhuravleva 《Catalysis in Industry》2018,10(2):118-125
The effect of the hydroisomerization conditions of the benzene-containing fraction of catalytic reforming gasoline on the yield and composition of products is studied on Pt/B2O3–Al2O3 and Pt/WO3–Al2O3 catalysts. These catalysts allow benzene to be completely removed from the raw material. At the same time, the greatest yields of liquid products are obtained with minimal losses of the octane number at 2 MPa, a mass feedstock hourly space velocity (MFHSV) of 2 h?1, and 325°C: 96.3 and 95.4 wt % on Pt/B2O3–Al2O3 and Pt/WO3–Al2O3 catalysts, respectively. The activity of the catalysts is maintained for 100 h during their operation. 相似文献
11.
F. Lian M. Gao W. H. Qiu P. Axmann M. Wohlfahrt-Mehrens 《Journal of Applied Electrochemistry》2012,42(6):409-417
With the aim of achieving a high-performance 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2 material, a series of 0.5Li2MnO3·0.5LiMn
x
Ni
y
Fe(1−x−y)O2 (0.3 ≤ x ≤ 0.5, 0.4 ≤ y ≤ 0.5) samples with low Fe content was synthesized via coprecipitation of carbonates. Its crystal structure and electrochemical
performance were characterized by means of powder X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron
spectroscopy, galvanostatic charge/discharge testing, cyclic voltammetry, and electrochemical impedance spectra. Rietveld
refinements with a model integrating R
[`3] \overline{3}
m and Fm
[`3] \overline{3}
m indicate that a low concentration of Fe incorporated in 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2 decrease a disordered cubic domain of the composite structure. The preferential distribution of Fe in cubic rock-salt contributes
to an unimaginable decrease of c-axis parameter of the predominant layered structure as the Fe content increases. Moreover, including Fe as a dopant can kinetically
improve crystallization and also change the ratio of Mn3+/Mn4+ and Ni3+/Ni2+. As a result, 0.5Li2MnO3·0.5LiMn0.4Ni0.5Fe0.1O2 exhibits lower Warburg impedance and higher reversible capacity than the undoped material. 相似文献
12.
13.
Jürgen Wackerl Thomas Koppitz Dong-Hyun Peck Sang-Kuk Woo Torsten Markus 《Journal of Applied Electrochemistry》2009,39(8):1243-1249
A copper-doped ferrite with the chemical composition La0.7Sr0.3Cu0.2Fe0.8O3−δ (LaSrCuFe) was prepared using the classical ceramics method starting from the oxides. The linear thermal expansion coefficient
in air was measured in the temperature range between 550 and 1,250 K to be between 10 × 10−6 and 15 × 10−6 K−1. The electrical conductivity in air was found to be higher than 100 S cm−1 for temperatures lower than 1,100 K. A change of oxygen stoichiometry was found above 650 K in an atmosphere of 20 vol% oxygen
with argon. This change can be correlated with the electrical conductivity. 相似文献
14.
Ternary IrO2–Sb2O5–SnO2 anode has shown its superiorities over IrO2 and many other electrocatalysts for O2 evolution, in terms of electrochemical stability, activity and cost. The performance of IrO2–Sb2O5–SnO2 anodes is affected by its electrochemical properties and operating conditions. In this paper, the electrochemical stability
and activity of the Ti/IrO2–Sb2O5–SnO2 anodes prepared with three different geometries were investigated under different operating conditions. It was found that
anodes with large mean curvature have high electrochemical stability. Although increasing temperature results in a decrease
in the stability of Ti/IrO2–Sb2O5–SnO2, the anode with a mean curvature of 200 m−1 still shows acceptable service life even at 70 °C. This tolerance of high temperature was attributed to the thermal expansion
difference between the substrate and the coating layer, the redox window for Ir(V)/Ir(IV) conversion, and the redox reversibility
of Sb and Sn species in the coating layer. 相似文献
15.
J. E. Anderson R. S. Bubnova S. K. Filatov V. L. Ugolkov S. N. Britvin 《Glass Physics and Chemistry》2009,35(2):191-198
The thermal behavior of ammonioborite (NH4)3[B15O20(OH)8] · 4H2O is investigated using thermal X-ray diffraction, differential thermal analysis (DTA) in air and vacuum, and thermogravimetry. It is shown that the decomposition of the mineral (dehydration, dehydroxylation, deammoniation) proceeds in several stages, and the dehydration is accompanied by the amorphization. The thermal expansion of ammonioborite is sharply anisotropic. As in the case of other hydrous pentaborates, the thermal expansion is maximum in the direction in which pentaborate groups alternate with ammonium cations. 相似文献
16.
Ron C. Runnebaum Tarit Nimmanwudipong Ryan R. Limbo David E. Block Bruce C. Gates 《Catalysis Letters》2012,142(1):7-15
Abstract
The conversion of 4-methylanisole, a prototypical bio-oil compound, was catalyzed by Pt/Al2O3, Pt/SiO2-Al2O3, or HY zeolite at 573 K and atmospheric pressure. More than a dozen products were formed with each catalyst, the most abundant being 4-methylphenol, 2,4-dimethylphenol, and 2,4,6-trimethylphenol; toluene was also a major product when the catalyst was supported platinum with H2 as a co-reactant. 4-Methylphenol was the only methylphenol isomer formed in significant yields, which indicates that migration of the methyl group on the aromatic ring is not significant under the selected reaction conditions. The data determine approximate reaction networks including reactions forming 4-methylphenol, 2,4-dimethylphenol, and toluene as primary products. The kinetically significant reaction classes were transalkylation, observed with all three catalysts, and hydrogenolysis (including hydrodeoxygenation) and hydrogenation, observed only with the platinum-containing catalysts operating in the presence of H2. Data such as those reported here provide a starting point for predicting the conversion of whole bio-oils for removal of oxygen and upgrading of fuel properties. 相似文献17.
Ultrafast pump-probe and transient photoluminescence spectroscopy were used to investigate carrier dynamics in β-Ga2O3 nanowires converted to β-Ga2O3/Ga2S3 under H2S between 400 to 600 °C. The β-Ga2O3 nanowires exhibited broad blue emission with a lifetime of 2.4 ns which was strongly suppressed after processing at 500–600 °C giving rise to red emission centered at 680 nm with a lifetime of 19 μs. Differential absorption spectroscopy reveals that state filling occurs in states located below the conduction band edge before sulfurization, but free carrier absorption is dominant in the β-Ga2O3/Ga2S3 nanowires processed at 500 to 600 °C for probing wavelengths >500 nm related to secondary excitation of the photo-generated carriers from the mid-gap states into the conduction band of Ga2S3. 相似文献
18.
Ceramic samples of Na0.55Co0.9M0.1O2 (M = Sc, Ti, Cr–Zn, Mo, W, Pb, Bi) solid solutions are synthesized using the solid-phase method; their crystal structure parameters are determined; their microstructure, thermal expansion, thermal and electrical conductivity, and thermal e.m.f. are studied; and the values of their power factor and thermoelectric figure of merit are calculated. It is revealed that Na0.55Co0.9M0.1O2 cobaltites are p type conductors with the linear thermal expansion coefficient (LTEC) changed within limits of (12.2–16.2) × 10–6 K–1. The effect of the substitution of other metal cations for cobalt cations in Na0.55CoO2 on the parameters of the crystal structure, as well as the physicochemical and functional properties of Na0.55Co0.9M0.1O2 solid solutions, which are formed, is analyzed. It is shown that ceramic samples of the Na0.55Co0.9Cr0.1O2 and Na0.55Co0.9Bi0.1O2 compositions have the maximal power factor values among those studied at 0.917 and 1.018 mW/(m K2), respectively, at a temperature of 1100 K. 相似文献
19.
Nanopowders with a composition of (СeO2)1–x(Gd2O3)x (x = 0.03, 0.05, 0.07, and 0.10) are synthesized by the coprecipitation method using cryotechnologies. The coherent scattering region (CSR) of the powders is 10–14 nm and the specific surface area is 70–81 m2/g. Based on the powders, ceramic nanosized materials with CRS of 64–71 nm are obtained. The dependence of the phase composition, microstructure, and electrical transport properties of the obtained samples on the Gd2O3 content is established. In a CeO2–Gd2O3 system, a solid solution with the composition of (CeO2)0.90(Gd2O3)0.10 has the highest ionic conductivity with the transfer number of ions of ti = 0.74 at a temperature of 700°C. It is shown that ceramics of this composition can be used as a solid electrolyte of intermediate-temperature fuel cells due to their physicochemical characteristics. 相似文献
20.
The influence of the electrode manufacturing procedure on surface and electrocatalytic properties for oxygen and ozone evolution at electrodes of nominal composition Ti/[IrO2–Nb2O5] (45:55 mol%) was investigated. Thermal decomposition at 450 °C (1 h, air stream) was adopted as standard procedure. Metal support pretreatment, solvent mixture, method of applying the precursor mixture and calcination procedure were all investigated. X-ray diffraction, scanning electronic microscopy, voltammetric and differential capacity analysis show the use of HCl 1:1 as solvent and applying the mixture by brush led to fragile rugged/porous oxide coatings. However, for the same conditions, but controlled calcination (heating/cooling rates), the coating becomes more compact. Using isopropanol as solvent results in a more homogeneous coating, presenting the lowest morphology factor. Kinetic investigation shows the rugged/porous coating presents the lowest Tafel slopes and the highest global electrocatalytic activity for OER. The more compact the coating the lower the electrochemically active surface area and the global OER activity. Ozone efficiency depends on the electrochemically active area while support pretreatment strongly influences the lifetime of the electrode. Application of a Pt interlayer between the oxide and Ti base improves the service life. 相似文献