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1.
The thermal behavior of the gels that are formed in the synthesis of MgFe1.6Ga0.4О4 powders was studied by differential scanning calorimetry and thermogravimetry (DSC–TG). The combustion temperatures of the gels in flowing air and flowing argon were determined from experimental data and thermodynamic calculations. The calculations of combustion temperatures from the heat flow of reaction versus time are shown to be a reliable tool to determine the parameters of gel combustion.  相似文献   

2.
A series of MoO3/ZrO2–Al2O3 catalysts was prepared and investigated in the sulfur-resistant methanation aimed at production of synthetic natural gas. Different methods including impregnation, deposition precipitation, and co-precipitation were used for preparing ZrO2–Al2O3 composite supports. These composite supports and their corresponding Mo-based catalysts were investigated in the sulfur-resistant methanation, and characterized by N2 adsorption–desorption, XRD and H2-TPR. The results indicated that adding ZrO2 promoted MoO3dispersion and decreased the interaction between Mo species and support in the MoO3/ZrO2–Al2O3 catalysts. The co-precipitation method was favorable for obtaining smaller ZrO2 particle size and improving textural properties of support, such as better MoO3 dispersion and increased concentration of Mo6+ species in octahedral coordination to oxygen. It was found that the MoO3/ZrO2–Al2O3 catalyst with ZrO2Al2O3 composite support prepared by co-precipitation method exhibited the best catalytic activity. The ZrO2 content in the ZrO2Al2O3 composite support was further optimized. The MoO3/ZrO2–Al2O3 with 15 wt % ZrO2 loading exhibited the highest sulfur-resistant CO methanation activity, and excess ZrO2 reduced the specific surface area and enhanced the interaction between Mo species and support. The N2 adsorption-desorption results indicated that the presence of ZrO2 in excessive amounts decreased the specific surface area since some amounts of ZrO2 form aggregates on the surface of the support. The XRD and H2-TPR results showed that with the increasing ZrO2 content, ZrO2 particle size increased. These led to the formation of coordinated tetrahedrally Mo6+(T) species and crystalline MoO3, and this development was unfavorable for improving the sulfur-resistant methanation performance of MoO3/ZrO2–Al2O3 catalyst.  相似文献   

3.
Solubility and stability of (NH4)2SO4·H2O2 in organic solvents (glycerol, ethylene glycol, TOSOL-A40 OM antifreeze), in mixtures of an organic solvent and water, and in pure water was studied. Crystallographic properties of the ammonium sulfate precipitating from aqueous-organic solvents and aqueous solutions in various time intervals and differing from ordinary (NH4)2SO4 in solubility and one of crystallographic parameters were analyzed.  相似文献   

4.
The structure of tri-μ2-disulfido-μ3-thiotris(diethyldithiocarbamato)-S,S′-triangle-trimolybdenum iodide [Mo33-S)(μ2-S2)3(Et2NCS2)3]I was determined. The compound was characterized by differential thermal analysis and IR, Raman, and X-ray electronic spectroscopy.  相似文献   

5.
The compound [Co(NH3)6]2[W4Se4(CN)12]·8.5H2O was obtained by evaporating an aqueous ammonia solution of K6[W4Se4(CN)12]·6H2O and CoCl2·6H2O complexes. The starting Co(II) of CoCl2·6H2O transforms into [Co(NH3)6]3+ when exposed to air in a water-ammonia medium. Crystal data: triclinic crystal system, a = 10.7750(8) Å, b = 12.2843(9) Å, c = 19.6539(14) Å; α = 90.213(2)°, β = 99.910(2)°, γ = 114.737(1)°, V = 2319.1(3) Å3, space group , Z = 2, D x = 2.633 g/cm3.Original Russian Text Copyright © 2004 by I. V. Kalinina, Z. A. Starikova, F. M. Dolgushin, D. G. Samsonenko, and V. P. Fedin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 905–908, September–October, 2004.  相似文献   

6.
Insight into the unique structure of layered double hydroxides (LDHs) has been obtained using a combination of X-ray diffraction and thermal analysis. Indium containing hydrotalcites of formula Mg4In2(CO3)(OH)12·4H2O (2:1 In-LDH) through to Mg8In2(CO3)(OH)18·4H2O (4:1 In-LDH) with variation in the Mg:In ratio have been successfully synthesised. The d(003) spacing varied from 7.83 Å for the 2:1 LDH to 8.15 Å for the 3:1 indium containing LDH. Distinct mass loss steps attributed to dehydration, dehydroxylation and decarbonation are observed for the indium containing hydrotalcite. Dehydration occurs over the temperature range ambient to 205 °C. Dehydroxylation takes place in a series of steps over the 238–277 °C temperature range. Decarbonation occurs between 763 and 795 °C. The dehydroxylation and decarbonation steps depend upon the Mg:In ratio. The formation of indium containing hydrotalcites and their thermal activation provides a method for the synthesis of indium oxide-based catalysts.  相似文献   

7.
The crystal structure of a double complex salt of the composition [Au(en)2]2[Cu(C2O4)2]3·8H2O (en = ethylenediamine) at 150 K is determined by single crystal X-ray diffraction. The crystal data for C20H48Au2Cu3N8O32 are: a = 9.1761(3) Å, b = 16.9749(6) Å, c = 13.4475(5) Å, β = 104.333(1)°, V = 2029.43(12) Å3, P21/c space group, Z = 2, d x = 2.450 g/cm3. It is demonstrated that the thermal decomposition of the double complex salt in a helium or hydrogen atmosphere affords the solid solution Au0.4Cu0.6.  相似文献   

8.
9.
Information on the across-plane conductivity of films of solid-oxide electrolytes SrZr0.95Y0.05O3–δ and CaZr0.9Y0.1O3–δ deposited on ion-conducting supports is acquired by the impedance method. It is shown that the support/film interface and the intergrain boundaries considerably affect the across-plane charge transfer in the film. The effect of the crystallographic orientation of the YSZ support on the microstructure and conductivity of the CaZr0.9Y0.1O3–δ electrolyte film is demonstrated.  相似文献   

10.
A method for producing synthetic troegerite of composition(UO2)3(AsO4)2 · 12H2. Owas developed. X-ray diffraction, IR spectrometry, X-ray fluorescence analysis, and scanning calorimetry were used to study its dehydration and thermal decomposition, to solve the structgure, and to determine X-ray diffraction and IR spectroscopic characteristics.  相似文献   

11.
The single crystals of Rb2[(UO2)2(C2O4)2(SeO4)] · 1.33H2O were synthesized and studied by X-ray diffraction. The crystals are monoclinic, space group P21/m, Z= 2, the unit cell parameters: a = 5.6537(8), b = 18.736(3), c = 9.4535(15) Å, β = 98.440(5)°, V = 990.6(3) Å3, R 1 = 0.0506. The main structural units of the crystal are infinite layers of [(UO2)2(C2O4)2(SeO4)]2?, corresponding to the crystal chemical group A2K 2 02 B2 (A = UO 2 2+ , K02 = C2O 4 2? , B2 = SeO 4 2? ) of uranyl complexes. The uranium-containing layers are united into a three-dimensional framework through the electrostatic interactions with the outer-sphere rubidium ions and the hydrogen bonding system involving the outer-sphere water molecules.  相似文献   

12.
Thin films of the perovskite and garnet structured gadolinium ferrites GdFeO3 and Gd3Fe5O12 have been synthesized by a sol–gel method, based on stoichiometric mixtures of acetyl acetone chelated Gd3+ and Fe3+ dissolved in 2-methoxy ethanol. After spin coating onto Si wafers, and heating in air at 700 °C for 20 h, neatly grown essentially single phase films were obtained. From X-ray photoelectron spectroscopy an iron deficiency is observed in the uppermost layer of both films, implying that the crystallites preferably end in planes rich in Gd and O but not in Fe. The films were also characterized by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, and magnetic measurements.  相似文献   

13.
A method for the synthesis of potassium pivalates (trimethylacetates) from potassium tert-butoxide and pivalic acid was proposed. The complexes of the formulas [K(H2O)(Piv)](I) and [K2(Phen)(H2O)2(Piv)2] (II) (Piv denotes the pivalate anion and Phen denotes 1,10-phenanthroline) were obtained and characterized by elemental analysis and IR and 1H NMR spectroscopy. The crystal structures of complexes I and II were determined using X-ray diffraction. Crystal structure I has a layered motif with two nonequivalent K atoms (C.N.s 5 + 2 and 6). The coordination of phenanthroline in II gives rise to a ribbon motif, the structure containing three nonequivalent K atoms (C.N.s 6, 6 + 1, and 8).  相似文献   

14.
Ionic mobility and electrical conductivity of solid solutions with fluorite structure, obtained with solid-state approach in PbF2–SbF3 and PbF2–SnF2–SbF3 systems, are studied by 19F NMR and electrochemical impedance spectroscopy methods. The 19F NMR spectra parameters, types of ion motions in the fluoride sublattice, and the ionic conductivity magnitude are shown to be determined by the temperature and fluoride concentration in the solid solutions. The solid solution specific conductivity in the PbF2–SbF3 and PbF2–SnF2–SbF3 systems at 420–450 K is as high as ~10–2 S/cm, which allows accounting the solid solutions as a base for preparation of functional materials.  相似文献   

15.
Phase equilibria were studied in the Nb2O5–CdO system in the Nb2O5-rich region including CdNb2O6 and Cd2Nb2O7. It was determined that CdNb2O6 and Cd2Nb2O7 in air are stable to 1150 and 1120°C, respectively, and that, above these temperatures, there is solid-phase decomposition of niobates with CdO release in the gas phase. Along with the cadmium oxide evaporation, the Cd2Nb2O7 decomposition is accompanied by the formation of cadmium metaniobate CdNb2O6 and the CdNb2O6 decomposition results in the formation of niobium oxide Nb2O5. No thermal events were observed in the differential thermal analysis curve for a 1: 1 CdNb2O6–Cd2Nb2O7 mixture heated to 1100°C in air, which suggests that there are neither phase transformations in cadmium niobates, nor a eutectic within this temperature and concentration ranges. A study of the morphology of compacted samples of niobates determined specific conditions for producing dense composite ceramics, a mixture of niobates, that is suitable for using as a dielectric material.  相似文献   

16.
The complex Na3(NH4)2[Ir(SO3)2Cl4]·4H2O was examined with single crystal X-ray diffraction and IR spectroscopy. Crystal data: a = 7.3144(4) Å, b = 10.0698(5) Å, c = 12.3748(6) Å, β = 106.203(1)°, V = 875.26(8) Å3, space group P21/c, Z = 2, d calc = 2.547 g/cm3. In the complex anion two trans SO 3 2? groups are coordinated to iridium through the S atom. The splitting of O-H bending vibrations of crystallization water molecules and N-H ones of the ammonium cation is considered in the context of different types of interactions with the closest neighbors in the structure.  相似文献   

17.
The title compound, cobalt 4′,7-diethoxylisoflavone-3′-sulfonate([Co(H2O)6](X)2⋅8H2O, X = C19H17O4SO3) was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic space group P-1 with cell parameters a = 9.026(3) Å, b = 16.431(5) Å, c = 18.195(6) Å, α = 72.289(4), β = 87.498(4), γ = 82.775(5), V = 2550.1(13) Å−3, Dc = 1.419 Mg m−3, and Z = 2. The results show that the title compound consists of one cobalt cation, six coordinated water molecules, eight lattice water molecules, and two 4′,7-diethoxylisoflavone-3′-sulfonate anions, C19H17O4SO3. Two anions have different conformations. Twelve H atoms of six coordinated water molecules, as donors, form hydrogen bonds with four oxygen atoms of sulfo-groups of two anions and eight oxygen atoms of eight lattice water molecules. In addition, π < eqid1 > ⋅ < eqid2 > π stacking interactions exist in the crystal structure, which together with hydrogen bonds lead to supramolecular formation with a three-dimensional network.  相似文献   

18.
Single crystals of Ba3[UO2(C2O4)2(NCS)]2 · 9H2O are synthesized and studied by X-ray diffraction. The crystals are orthorhombic, space group Fddd, Z = 16, and the unit cell parameters are a = 16.253(3) Å, b = 22.245(3) Å, c = 39.031(6) Å. The main crystal structural units are mononuclear complex groups [UO2(C2O4)2NCS]3? of the crystal-chemical family (AB 2 01 M1 (A = UO 2 2+ , B01 = C2O 4 2? , M1 = NCS?) of the uranyl complexes linked into a three-dimensional framework by electrostatic interactions and hydrogen bonds involving oxalate ions and water molecules.  相似文献   

19.
Radiation-induced degradation of the weakly and strongly 4-vinylpyridine basic ion exchange resins by gamma radiolysis was investigated in the presence of air and liquid water. This study is focused on evaluating the radiolytic gases (H2, CO, CO2 and CH4) and liquid products (water-solute TOC and NH4 +). The weakly basic resin yielded lower amounts of H2 and CO and higher amounts of CO2 than those of the strongly basic resin. Moreover, the strong basic resin tended to yield greater amounts of NH4 +. Resins were characterized by the FTIR spectroscopy technique and the results showed that the resins structures are relatively stable.  相似文献   

20.
Bismuth titanate (Bi4Ti3O12) and bismuth titanium niobate (Bi3TiNbO9) c-axis textured thin films were fabricated using the sol–gel processing technique. Chemical modification of precursor solutions was performed using a proprietary photosensitive chemical (photoresist). Increases in crystallinity and texture of resulting films were seen over films that were made from unmodified solutions. Analysis by X-ray diffraction (XRD) revealed c-axis orientation factors for Bi4Ti3O12 near 88% and Bi3TiNbO9 near 63% in “modified” films. Atomic force microscopy images of films show microstructural improvement between “modified” and “unmodified” films. Images generally show smaller randomly oriented grains in “unmodified” films, and larger oriented platelet structures related to growth due to crystal habit in “modified” films. Light scattering experiments show the addition of photoresist to the precursor solution initiates accelerated particle growth. AFM imaging of soft-baked films also suggests an enhancement of texture.  相似文献   

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