Continuous Determination of the Oxidation State in a Soda-Lime-Silica Glassmelt During Refining

Influences on the oxidation state of glassmelts can be studied by using an electrochemical oxygen sensor which allows in-situ measurements at melting temperatures. The action of fining agents such as arsenic and sodium sulfate was investigated. The behavior of arsenic (i.e. release and uptake of oxygen) and the decomposition of sodium sulfate with and without carbon additions can be seen electrochemically.     

铝合金表面钒酸铈改性环氧涂层的制备与性能研究

通过水热合成法制备钒酸铈(CeVO4)纳米填料,将CeVO4分散到环氧树脂中获得改性涂层.分别涂覆在打磨后碱洗处理铝合金和直接喷砂处理铝合金上.采用XRD、FT-IR和SEM对CeVO4粉体进行表征,并通过附着力测试、电化学阻抗和长期浸泡实验对改性前后的涂层进行研究.结果表明:利用水热合成法可成功制备CeVO4纳米填料...     

氧化铈含量的直接测定法

介绍了一种直接测定氧化铈含量的新方法。在硫酸溶液中,采用过氧化氢将氧化铈中的Ce^4 还原为Ce^3 。样品溶解完全后,用过硫酸铵将Ce^3 氧化成Ce^4 ,用硫酸亚铁铵标准溶液滴定,Ce^4 将硫酸亚铁铵中的Fe^ 氧化成Fe^3 ,根据消耗的标准溶液的体积计算氧化铈含量。该方法相对标准偏差为0．0394％,回收率为99．94％。该方法快速、准确,具有良好的精密度和准确度。     

铈—二甲酚橙络合物极谱催化波测定微量铈的研究

研究发现铈－ 二甲酚橙络合物在导数示波极谱中能形成灵敏的催化波，并且获得了形成这种催化波的最佳条件，对铈－ 二甲酚橙络合吸附催化波的形成机理作了初步的分析。探讨了把这种新的催化体系用于测定微量铈的方法，此法具有灵敏度高，干扰小，分析过程简单迅速的优点，测定最低浓度可达２ ．８×１０－ ７ｍｇ／Ｌ，特别适用于检测样品中的微量铈。     

Oxidation of Powdered Alloys of Aluminum and Cerium during Heating in Air

The effect of cerium on the oxidation of powdered alloys of aluminum and cerium during heating in air at temperatures up to 1773 K was studied using derivatography, xray phase analysis, and thermal desorption of argon. It is established that the rate and completeness of the oxidation of aluminum increase if it is alloyed with cerium. The effect of cerium is due to its polyvalence, high reactivity, and surface activity toward aluminum. Structural and phase nonuniformities that arise during the growth of oxide phases on the surface of oxidized particles of the alloys enhance the interaction of these particles with air oxygen. It is shown that the assumptions that the surfaces of the alloys have a micrononuniform structure and are enriched with CeAl₂ and CeAl₄ groups are valid.     

氧化还原-邻菲罗啉分光光度法测定玻璃中铈的研究

采用在无银（Ⅰ）催化、0．5mol／L硫酸、0．1g／L过硫酸铵的溶液中,加热煮沸10min将铈（Ⅲ）氧化成铈（Ⅳ）后,加入一定量过量的Fe^2＋或Fe（Phen）3^2＋溶液与之作用,过量物在避光条件下用邻菲罗啉分光光度法测定,从而测得玻璃中的铈含量。分析了玻璃中的微量二氧化铈,S=0．002496,Cv〈5％,相对误差〈8％。前人的诸多研究都没有注意到溶液中存在的光化学还原干扰。     

硫酸铈氧化对二甲苯制对甲基苯甲醛

用硫酸铈为媒质间接电氧化对二甲苯制对甲基苯甲醛。在优选的条件下，电氧化Ｃｅ（ＩＶ）的产率≥８５％。采用十二烷基硫酸钠等催化剂可以明显地加速合成对甲基苯甲醛的反应。     

Supercritical Water Oxidation: State of the Art

The oxidation of harmful organic compounds contained in aqueous waste effluents known as s uper c ritical w ater o xidation, SCWO, has been worked out since the 1980s. This highly efficient end of the pipe process operates at pressures and temperatures above 221 bar and 374 °C, the critical point of water. R&D experience and the technological state including economical and regulatory aspects are reviewed and further R&D needs are discussed in this article. Future applications are also seen in coupling supercritical CO₂ extraction with oxidation to treat contaminated materials and in s uperc ritical w ater g asification, SCWG, to convert biomass and organic wastes to hydrogen.     

Determination of the Oxidation State of Antimony, Iron and Vanadium in Mixed Vanadium and Iron Antimonate Oxide Catalysts

Vanadium and mixed vanadium and iron antimonates with rutile-type structures have been studied by XANES at Sb L₁ edge, ⁵⁷Fe Mössbauer spectroscopy and ESR spectroscopy at 77 K. The results showed that both antimony and iron remained at their highest oxidation state, i.e. Sb^V and Fe^III, whereas vanadium was present as V^III and V^IV. Two types of V^IV species were distinguished corresponding to well-isolated vanadyl species in distorted octahedral coordination and vanadyl species in the same coordination but close to each other and in a dipole–dipole interaction. Both V^III and total V^IV concentrations decreased when the iron content increased, whereas isolated V^IV concentration increased first and then decreased, with a maximum for x = 0.2 in Fe_xV_1-xSbO₄. The observed variations in cationic composition are discussed in relation with the catalytic properties of the compounds in the ammoxidation of propane. Isolated V^IV-O moieties appeared to be the most active and selective catalytic sites.     

The Chemistry of Platinum in the +3 Oxidation State

Platinum(III) is no longer an uncommon oxidation state. Numerous binuclear platinum(III) complexes have been prepared and structurally characterized over the past eight years. These include sulfate-bridged dimers of D_4h symmetry, [Pt₂(SO₄)₄L₂]²⁻, L = H₂O, DMSO; phosphate-bridged complexes [Pt₂(HPO₄)₄-(H₂O)₂]²⁻ and [Pt₂(H₂PO₄)(HPO₄)₃(py)₂]⁻; POP (H₂ P₂ O²⁻₅)-bridged ions [Pt₂-(POP)₄X₂]²⁻, X = halide; an extensive series of α-pyridonate (C₅H₄NO⁻)-bridged head-to-head and head-to-tail complexes, [Pt₂(NH₃)₄ (C₅H₄NO)₂XY]ⁿ⁻, X, Y = NO₃, NO₂, H₂O, Cl, Br; n = 2, 3; and organometallic derivatives such as [Pt₂(CH₃)₄-(CF₃CO₂)₂(4-Mepy)₂]. In all cases there is a Pt–Pt single bond of length 2.47–2.7 Å, pseudo-octahedral geometry about platinum, and two or more bridging ligands. The complexes are stable in solution and some undergo quasi-reversible two-electron redox reactions. Mononuclear platinum(III) complexes are less well characterized structurally, but have been stabilized in diamagnetic host lattices in the solid state and by macrobicyclic cage ligands in solution following pulse radiolytic or γ-irradiation of precursor platinum(II) complexes. The first unequivocal, crystallographically characterized mononuclear platinum(III) complex, [Pt(C₆Cl₅)₄]⁻, has just been reported.     

Amperometric Determination of Cerium and Vanadium,and Cerium and Molybdenum in Their Binary Mixtures Using Two Indicator Electrodes

In recent studies in this laboratory, the amperometric method has been applied for the successive determination of cerium and iron [1] and a number of other elements in their binary mixtures [2–3]. In the present investigation this method has been extended for the estimation of mixtures of cerium and vanadium or cerium and molybdenum, using ascorbic acid as titration reagent.     

Control Reaction Path of CO Oxidation by Regulating the Oxidation State of Au Species

Reaction path of CO oxidation in the presence and the absence of hydrogen can be well controlled by regulating the oxidation state of Au species via addition of appropriate dopant, which resulted in different product distribution.     

汽车用铝合金阳极氧化及钵转化膜封闭技术

采用阳极氧化和钵转化膜封闭技术提高汽车用2036铝合金的耐蚀性。研究发现:铝合金阳极氧化膜由外部的多孔层和内部的阻挡层构成,多孔层孔径均匀,约为30 nm0经过阳极氧化处理后,铝合金的自腐蚀电位正移,自腐蚀电流密度下降,耐蚀性提高。经过钵转化膜封闭处理后,大量钵的氢氧化物覆盖阳极氧化膜表面,进一步提高了铝合金的耐蚀性。     

Catalytic Oxidation of Ethene on Polycrystalline Palladium: Influence of the Oxidation State of the Surface

¹³C DEPT-MRI is used to provide the first spatial mapping of alkene isomerisation and hydrogenation during an alkene hydrogenation reaction occurring within a trickle-bed reactor. The implementation of a pulse sequence combining the spatial resolution of a magnetic resonance imaging (MRI) pulse sequence with a ¹³C DEPT magnetic resonance spectroscopy pulse sequence enables spatially resolved ¹³C spectra to be recorded of natural abundance ¹³C species. Observation of the ¹³C nucleus, which has a much larger chemical shift range than the ¹H nucleus, provides spectra from which direct identification of the products of isomerisation and hydrogenation is achieved. This technique is illustrated with respect to the hydrogenation of 1-octene over a 1 wt% Pd/Al₂O₃ catalyst. In this preliminary study we demonstrate the ability of this technique to identify the effect of changing the hydrogen flow rate on the evolution of isomerisation and hydrogenation processes occurring along the length of the bed.     

Regioselective Oxidation of Polyalkoxy Naphthalenes: Formation of Naphthoquinones by Ammonium Cerium(IV) Nitrate Oxidation of Methoxymethyl Ethers

A proper choice of methoxy and methoxymethyl groups for protection of the hydroxyls of polyoxygenated naphthalenes allows selective oxidation of either ring of the naphthalene structure with ammonium cerium(IV) nitrate; for example, 9 can be converted into 10 , and 11 into 12.     

褪色分光光度法测定碱性锌-铈合金镀液中的铈

研究了褪色分光光度法测定碱性锌-铈合金镀液中的铈的质量浓度,在盐酸介质中,铈(Ⅳ)的强氧化性能使三溴偶氮胂褪色,表观摩尔吸光系数ε660nm=2.1×104(L·mol-1·cm-1),铈(Ⅳ)的质量浓度在0～14μg/mL范围内符合比尔定律。方法快速,准确,简便。     

Ferroelastic Toughening in Bismuth Vanadate

Bismuth vanadate has been used as a model system to examine toughening by stress-induced domain motion in a ferroelastic materials. Fracture toughnesses in the ferroelastic and paraelastic states have been compared. Toughening and R -curve behavior have been observed in the ferroelastic state. Single crystals of BiVO₄ show domain nucleation and propagation under compressive loading and domain generation during fracture. The increase in toughening in the ferroelastic state can be explained by a combination of crack deflection and domain wall motion, the latter contributing to R -curve behavior.     

Determination of Oxidation of Methyl Ricinoleates

Ricinoleate esters have desirable properties as biolubricants, but their oxidative stability has been questioned. To systematically study the stability of ricinoleate ester and its derivative, methyl esters of castor oil were prepared and methyl ricinoleate was isolated by solvent partitioning. Methyl 12‐acetyl ricinoleate was synthesized from the methyl ricinoleate by interesterification with excess methyl acetate and was then purified by solvent partitioning. The rates of oxidation of methyl linoleate, methyl oleate and the two ricinoleate esters were measured by oxidation of lipid dispersed on glass beads under three temperatures (40–80 °C). The relative amounts of the unoxidized methyl esters were determined periodically by gas chromatography, and the peroxide value of the oils was also determined. The oxidation rates were determined as the peroxide value increase rate, as well as the ester disappearance rate, and the stability of the various esters was compared. Overall, methyl ricinoleate was much more oxidatively stable than methyl oleate at mildly elevated temperatures, and the acetylation of the hydroxyl group on the 12th carbon decreased the stability.