制备工艺对NiFe2O4分解CO2活性的影响

随着大气中CO2浓度的增加,温室效应日趋严重,促使人们对大气中CO2的转化与消除这一课题更加重视。1990年Yutaka Tamaura[1]发现氧缺位磁铁矿几乎可以100%分解CO2后,为解决温室效应提供了一条新的探索途径。通过对不同铁酸盐MFe2O4(M=Fe,Mn[2],Co[3],Zn[4],Ni[5]等)分解CO2活性的考察,发现铁酸镍在300℃分解CO2的活性比其它铁酸盐都好。NiFe2O4的制备最常采用的是共沉淀法、柠檬酸溶胶凝胶法和水热法,3种方法由于制备     

Biodistribution and toxicity assessment of radiolabeled and DMSA coated ferrite nanoparticles in mice

DMSA-coated Fe₃O₄ nanoparticles were synthesized by wet-chemical method. The chemical interaction between Fe₃O₄ and DMSA were investigated by FTIR. They were directly radiolabeled with ^99mTc radioisotope (Fe₃O₄@DMSA–^99mTc) at room temperature in the presence of stannous solution as a reducing agent. Magnetic and structure properties of Fe₃O₄@DMSA–^99mTc nanoparticles were investigated by AGFM, TEM, and XRD. Biodistribution and toxicity assessment of Fe₃O₄@DMSA–^99mTc were studied in mice by intravenous and intraperitoneally injections, respectively. Blood, kidney, and liver factors were measured 4 days post injection and at the mean-while tissue sections were prepared from their kidney and liver. The results indicate that, the Fe₃O₄@DMSA–^99mTc nanoparticles were passed through the membrane of different cells but do not create any disorder in the kidney and liver function even in high doses such as 300 mg/kg.     

Synthesis and photocatalytic activity assessing of the TiO<Subscript>2</Subscript> nanocomposites modified by some lanthanide ions and tin-derivative sandwich-type polyoxometalates

New nanocomposites containing sandwich-type polyoxometalate of [(PW₉O₃₄)₂(HOSn^IVOH)₃]^12? (P₂W₁₈Sn₃) loaded onto Ln-doped TiO₂ (Nd, Sm, Dy, Tb) nanoparticles were synthesized and their catalytic activities were assessed. The Ln–TiO₂ nanoparticles and Ln–TiO₂/P₂W₁₈Sn₃ nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, field emission scanning electron microscope, energy dispersive analysis of X-rays spectra and diffuse reflectance spectra. The photocatalytic efficiency of the Ln–TiO₂ and Ln–TiO₂/P₂W₁₈Sn₃ were examined in the photodegradation of methyl orange and methylene blue solutions. It was revealed through different characterization techniques that the P₂W₁₈Sn₃ was successfully loaded on the lanthanide-doped anatase phase TiO₂ nanoparticles and the particles diameter were relatively 20–30 nanometers. It was revealed that doping by the lanthanide ions followed by loading of polyoxometalates improves the photocatalytic performance of TiO₂ effectively. The effects of operational parameters and the kinetics of photocatalytic degradation under UV light were discussed. The prepared nanocomposites were stable and could be easily separated from the reaction system.     

Selective extraction of gadolinium from Sm2O3 and Gd2O3 mixtures in a single step assisted by MgCl2 in LiCl–KCl melts

The chloration of MgCl₂ was studied in the LiCl–KCl–MgCl₂–Gd₂O₃–Sm₂O₃ melts. Gd(III) and Sm(III) ions were observed by cyclic voltammetry and square wave voltammetry assisted by MgCl₂ in melts. X-ray diffraction (XRD) patterns of melts indicated Gd₂O₃ and Sm₂O₃ were chlorinated by MgCl₂ and formed GdCl₃ and SmCl₃. XRD patterns of non-dissolved residues, which were left after the melts were washed with water to remove the soluble salt, showed that the new compounds (i.e., GdOCl, SmOCl, MgO, Gd(OH)₃, and Sm(OH)₃) were produced. Potentiostatic electrolysis experiments were performed to extract Gd from Gd₂O₃ and Sm₂O₃ mixtures assisted by MgCl₂. Separation between Gd₂O₃ and Sm₂O₃ was also achieved in a single step with the formation of Mg–Li–Gd alloys. XRD patterns of alloys indicated that Mg₃Gd phase was formed. Scanning electron microscope images with energy dispersive X-ray spectroscopy showed Gd elements were mainly distributed in the grain boundary.     

A comparison study between sodium dodecyl sulfate and sodium dodecyl sulfonate with respect to the thermodynamic properties,micellization, and interaction with poly(ethylene glycol) in aqueous solutions

The density, sound velocity, and conductivity measurements were performed on aqueous solutions of sodium dodecyl sulfate (C₁₂H₂₅SO₄Na) or sodium dodecyl sulfonate (C₁₂H₂₅SO₃Na) in the absence and presence of poly(ethylene glycol) (PEG) at different temperatures. Changes in the apparent molar volumes and isentropic compressibilities upon micellization were derived using a pseudophase-transition approach and the infinite dilution apparent molar properties of the monomer and micellar form of C₁₂H₂₅SO₄Na and C₁₂H₂₅SO₃Na were determined. Variations of the critical micelle concentrations (CMCs) of both surfactants in the solutions investigated with temperature were obtained from which thermodynamic parameters of micellization were estimated. It was found that at low temperature the micelle formation process is endothermic and therefore, this process must be entropically driven. However, upon increasing the temperature, the enthalpic factor becomes more significant and, at temperatures higher than 303.15 K the micellization is enthalpy driven. The interactions between C₁₂H₂₅SO₄Na/C₁₂H₂₅SO₃Na and PEG were studied and it was found that sodium alkyl sulfonates were seen to interact more weakly than their sulfate analogues.     

硫中毒对Co3O4/CeO2复合氧化物上炭黑催化燃烧的影响

采用共沉淀法制备了CeO₂,Co₃O₄和一系列Co₃O₄/CeO₂复合氧化物催化剂,在400 ℃下含SO₂的氧化气氛中对催化剂进行了硫中毒处理,通过原位红外光谱、X射线衍射、程序升温脱附和X射线光电子能谱对新鲜和硫中毒的样品进行了表征. 结果表明,所有测试的硫中毒样品上均形成了硫酸盐,CeO₂上累积的硫酸盐明显比Co₃O₄上的多,Co₃O₄/CeO₂复合氧化物在硫中毒过程中形成了硫酸钴和硫酸铈. 对新鲜和硫化样品在NO/O₂气氛下进行了催化炭黑燃烧实验,发现Co₃O₄/CeO₂复合氧化物的活性和抗硫性能优于CeO₂,但抗硫性能低于Co₃O₄.     

Phase Equilibria in the System Tl<Subscript>9</Subscript>SbSe<Subscript>6</Subscript>–TlSbSe<Subscript>2</Subscript>–Tl<Subscript>4</Subscript>SnSe<Subscript>4</Subscript>

For the first time, by differential thermal, X-ray powder diffraction, and microstructural analyses, phase equilibria in the ternary system Tl₉SbSe₆–TlSbSe₂–Tl₄SnSe₄ were investigated and the state diagram of the polythermal section Tl₄SnSe₄–Tl₃SbSe₃, the projection of the liquidus surface on the concentration triangle, and the isothermal section at 423 K were constructed. The types and coordinates of invariant processes, the lines of monovariant equilibria, and their temperature ranges were found. The formation mechanism and nature of solid solutions based on ternary compounds Tl₉SbSe₆ and TlSbSe₂ were studied in terms of crystal chemistry.     

Phase equilibria in the La<Subscript>2</Subscript>S<Subscript>3</Subscript>-Bi<Subscript>2</Subscript>S<Subscript>3</Subscript>-La<Subscript>2</Subscript>O<Subscript>3</Subscript> ternary system

Phase equilibria in the La₂S₃-Bi₂S₃-La₂O₃ ternary system were studied by differential thermal, X-ray powder diffraction, and microstructure analyses. Phase diagrams of five vertical sections and a liquidus surface projection were plotted for the La₂S₃-Bi₂S₃-La₂O₃ system. The regions of primary crystallization of phases and coordinates of non- and monovariant equilibria were determined for the system.     

Syntheses of Poly(butylene succinate) by Means of Non-Toxic Catalysts

The usefulness of bismuth, calcium, magnesium and zinc salts for the preparation of poly(butylene succinate), PBSu, was studied. Two different approaches were compared. Firstly, 1,4-butanediol (or in a few experiments ethanediol) dimethyl succinate were condensed at temperatures up to 240°C in the presence of Bi₂O₃. Regardless of the feed ratio, only low molar mass polyesters having two diol endgroups were obtained. Secondly, 1,4-butanediol and succinic anhydride were polycondensed in refluxing decalin with azeotropic removal of water. BiCL₃, BiBr₃, BiI₃, and Bi-triflate were used as catalyst and the monomer/catalyst ratio was varied. The highest molar masses were achieved with BiCl₃. Analogous polycondensations catalysed with ZnCl₂, Zn-triflate, MgCl₂, Mg-triflate and CaCl₂ were unsuccessful. Yet the BiCl₃, decalin method was also successfully applied to the combination of succinic anhydride and 1,5-pentanediol.     

New complex silver-scandium vanadates

New complex silver-scandium vanadates, Ag₃Sc(VO₄)₂, AgBaSc(VO₄)₂, and Ag₃Sc₂(VO₄)₃, were synthesized, and their crystallographic parameters were determined. The products synthesized by different methods were studied by X-ray powder diffraction, electron-probe X-ray microanalysis, and ESR. Based on these data, the synthetic procedures were optimized. The thermal properties of complex vanadates were studied by DTA. The compounds AgBaSc(VO₄)₂ and Ag₃Sc₂(VO₄)₃ were shown to exhibit polymorphism. The compounds Ag₃Sc(VO₄)₂, AgBaSc(VO₄)₂, and Ag₃Sc₂(VO₄)₃ decompose at 760, 780, and 960 °C. respectively.     

Study of oxidative dehydrogenation of ethylbenzene with CO2 on supported CeO2-Fe2O3 binary oxides

Nano-sheets Al₂O₃ supported CeO₂-Fe₂O₃ binary oxides were prepared by the vacuum impregnation method. The structural and textural properties were characterized by pertinent techniques, and the materials were evaluated as catalysts for the oxidative dehydrogenation of ethylbenzene with carbon dioxide (CO₂-ODEB). The characterization results show that all samples maintain the hierarchical structure, and CeO₂-like and Fe₂O₃-like solid solutions were formed when changing the Ce-to-Fe molar ratio. The catalytic performances indicate that CeO₂-Fe₂O₃ binary oxides were effective for CO₂-ODEB, and the activity is determined by mobile oxygen, which can facilitate the dehydrogenation process. The DFT studies further identified the reaction pathway and rate-determining step. The inter-transmission of oxygen species and the presence of CO₂ refill the oxygen vacancies and restore the redox cycle of CeO₂-Fe₂O₃ binary oxides.     

选择氧化物载体调变乙醇重整和1,3-丁二烯加氢反应双金属催化剂

研究了不同载体负载的Pt-Ni双金属和单金属催化剂上乙醇重整和1,3-丁二烯加氢反应性能, 以考察氧化物载体对双金属结构和催化活性的影响. 所用的氧化物载体包括γ-Al₂O₃, SiO₂, TiO₂, CeO₂以及高比表面积(HSA)和低比表面积(LSA)ZrO₂. 采用共浸渍法制备催化剂, 用CO化学吸附、透射电镜和扩展X射线吸收精细结构光谱进行催化剂表征, 采用傅里叶变换红外间歇反应器进行化学反应评价. 对于乙醇重整反应, Pt-Ni双金属催化剂优于单金属催化剂, Pt-Ni双金属催化剂活性顺序为TiO₂ > SiO₂ > γ-Al₂O₃ ≈ LSA-ZrO₂ > CeO₂ > HSA-ZrO₂. 对于1,3-丁二烯加氢反应, 在SiO₂, TiO₂和HSA-ZrO₂载体上双金属催化剂优于单金属催化剂, Pt-Ni双金属催化剂活性顺序为SiO₂ > CeO₂ > γ-Al₂O₃ > LSA-ZrO₂ > HSA-ZrO₂ ≈ TiO₂.     

Construction and characterization of alkoxy-derived (Y,Yb)MnO<Subscript>3</Subscript>/HfO<Subscript>2</Subscript>/Si structures for FeRAM application

(Y,Yb)MnO₃ and HfO₂ films were prepared using alkoxy-derived precursor solutions, and (Y,Yb)MnO₃/HfO₂/Si structures were fabricated. The thickness, surface uniformity and crystallinity of the HfO₂ film affect the crystallization of Y_0.5Yb_0.5MnO₃ films. The degree of c-axis orientation and crystallinity of the Y_0.5Yb_0.5MnO₃ films were changed with preparation conditions of HfO₂ films. It was difficult to obtain Y_0.5Yb_0.5MnO₃ films with high crystallinity and high degree of c-axis orientation on the HfO₂ films thinner than 10 nm. The degree of c-axis orientation and crystallinity of the Y_0.5Yb_0.5MnO₃ films on HfO₂ films were improved by using diluted HfO₂ precursor solution in the case of 10 nm-thick HfO₂ film. Following this, the capacitance-voltage (C-V) characteristics were improved.     

Influence of pH on the incorporation and growth of Pb<Subscript>2</Subscript>CrO<Subscript>5</Subscript> crystallites in silica matrix

Pb₂CrO₅ nanoparticles were embedded in an amorphous SiO₂ matrix by the sol–gel process. The pH and heat treatment effects were evaluated in terms of structural, microstructural and optical properties from Pb₂CrO₅/SiO₂ compounds. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), and diffuse reflectance techniques were employed. Kubelka–Munk theory was used to calculate diffuse reflectance spectra that were compared to the experimental results. Finally, colorimetric coordinates of the Pb₂CrO₅/SiO₂ compounds were shown and discussed. In general, an acid pH initially dissolves Pb₂CrO₅ nanoparticles and following heat treatment at 600 °C crystallized into PbCrO₄ composition with grain size around 6 nm in SiO₂ matrix. No Pb₂CrO₅ solubilization was observed for basic pH. These nanoparticles were incorporated in silica matrix showing a variety of color ranging from yellow to orange.     

Crystal growth of SnO2 and other MO2 (M = Ti,Zr, Hf) oxides by flux of B2O3?V2O5 system

Single crystals of SnO₂ and MO₂ (M = Ti, Zr, Hf) oxide were grown from flux of B₂O₃? V₂O₅ system. Mixtures of the flux and the starting powder of Zn₂SnO₄, TiO₂, ZrO₂, or HfO₂ were soaked at a temperature of 1030–1340°C for 10–72 hr and then were cooled down to 900°C at a rate of 5°C/hr. Grown crystals of SnO₂ were pale brown needles. An increase in V₂O₅ content of the flux (up to V₂O₅/B₂O₃ ratio equal to 2) or in the soaking temperature increases the crystal size. A largest crystal with the size of 15.0 × 0.4 × 0.4 mm was obtained in the case of V₂O₅/B₂O₃ = 2. Crystals of TiO₂ were black needles or platelets, and those of ZrO₂ and HfO₂ were yellowish, transparent needles or blocks. The maximum size of TiO₂, ZrO₂ or HfO₂ crystal was 12.0 × 0.1 × 0.1 mm, 4.0 × 0.3 × 0.3 mm or 11.0 × 0.6 × 0.6 mm, respectively. The long axis of the crystals was all C-axis and main faces on the crystals were of {100} and/or {110} families. All these crystals were found to include the impurities of boron and vanadium. The electrical resistivities of SnO₂ and TiO₂ crystals were measured to be 1.4 × 10⁶ and 5.6 × 10⁴ Ω · cm at 25°C, respectively.     

Preparation of modified γ-alumina as stationary phase in gas–solid chromatography and its separation performance for hydrogen isotopes

On the basis of impregnation method, several stationary phases were prepared using γ-Al₂O₃ with the solution of transition metal salts and the breakthrough curves of gas chromatograph for H₂ isotopes were analyzed under the temperature of liquid nitrogen. The effects of carrier gas, flow rate and doping concentration on the separation performance for H₂ and D₂ were systematically investigated. The overall results showed that the surface areas and adsorptive capacities of modified γ-Al₂O₃ were slightly lower than unmodified one while the separation performance and symmetry of chromatographic peaks of the former were more excellent. In addition, the chromatographic peaks of ortho- and para-H₂ were no longer separated and the retention time shortened to half on columns of modified γ-Al₂O₃. All the magnetic transition metal ions modified γ-Al₂O₃ did very well for the separation of H₂/D₂ under the conditions of neon as carrier gas with a flow rate of 60 mL/min and column lengths of 1.0 m and injection amounts of 0.1 mL. Especially, the MnCl₂ modified γ-Al₂O₃ exhibited the best performance for separating H₂/D₂ with an optimum doping concentration of 20 wt%.     

Barriers to internal rotation in 1,3,5-trineopentylbenzenes: 10—13C and 19F NMR band shape studies and force field calculations

1,3,5-Trineopentylbenzenes (TNB) with one or two benzylic substituents in each neopentyl group were synthesized. The substituents were F, Cl, Br, J, OCH₃, OCOCH₃, OSi(CH₃)₃ and CH₃ and, in cases of disubstitution, F, Cl, Br, CH₃ and Cl, CH₃ and Br and ? SCH₂CH₂S? . Barriers to internal C_sp3? C_sp2 (aryl) and C_sp3? C_sp3 rotation were estimated by ¹³C and ¹⁹F NMR band shape methods. Estimated barriers in the TNB series were found to be very close to those found for the corresponding mononeopentylbenzenes. For some of the compounds studied, molecular mechanics (MM) calculations were performed with the Allinger MMP1 program. Differences between calculated and experimental estimated barriers were found, and possible sources of these discrepancies in terms of parameters used in the MMP1 program are discussed.     

Anodic synthesis and XPS analysis of La_(1-x)Na_xCu_2O_4

The single phase La1-x NaxCu2O4 crystals were synthesized by an electrochemical method from molten KOH/NaOH/KNO3 at 280-300℃ while La2-yNayCuO4 were prepared by precipitation from the same molten salt. The resulting crystals were characterized by using SEM, XRD, EDX and XPS. XPS analysis revealed that the La3d satellite structures of La1-xNaxCu2O4 were quite different from those of La2-yNayCuO4. These differences have been attributed to the changes in crystal structures, bond lengths and covalent character of the metal-ligand bonds.     

Preparation and Characterization of (Ba,Ca)(Ti,Zr)O3 Thin Films Through Sol-Gel Processing

(Ba_0.92,Ca_0.08)(Ti_0.92,Zr_0.08)O₃ thin films were prepared from Ba-Ti and Ca-Zr precursors by sol-gel processing. Polymerizable solutions containing Ba-Ti and Ca-Zr, respectively, were newly synthesized. Decomposition of the starting compounds and crystallization behavior of the film were examined by using TG/DTA and XRD. Microstructure of thin films was observed by using SEM. Polycrystalline (Ba_0.92,Ca_0.08)(Ti_0.92, Zr_0.08)O₃ films obtained by firing at 800°C were dense with fine grains. The thin films showed a dielectric constant of 1200 and dielectric loss of 0.5%.     

Synthesis and properties of tetraalkylammonium chlorides peroxosolvates (CH3)4NCI·H2O2 and (C2H5)4NCl·H2O2

Tetraalkylammonium chlorides peroxosolvates (CH₃)₄NCl·H₂O₂ and (C₂H₅)₄NCl·H₂O₂ were synthesized. The composition of the solvates was proved by chemical analysis; their X-ray patterns, IR spectra, and thermograms were obtained. The solubility of the solvates in water and their stability in aqueous solutions were investigated.