含肼钒盐热分解制备三氧化二钒

近年来,低价(或混合价)金属氧化物和超细化合物在磁、电、光、色等方面的特性,越来越受到人们的关注。V_2O_3可作催化剂,常用H_2还原V_2O_5或NH_4VO_3来制备。 前文曾用钨酸肼和含肼铝盐热分解,制得了蓝色氧化钨(WO_(2.90))和细颗粒α-Al_2O_3,在此基础上,本文报道用含肼钒盐热分解制备V_2O_3并对它的某些物理性能进行了测定。 1 实验部分     

Formation of copper(II) oxide nanostructures in porous glass as revealed by electrical conductivity measurements

Copper(II) oxide was synthesized in a glass matrix by multiple cycles of impregnation of porous glass with an aqueous solution of copper nitrate, followed by dehydration and thermal decomposition of the salt. The electrical conductivity and its temperature dependences, measured during the progressive accumulation of copper(II) oxide in porous glass, are indicative of a gradual change from chains to 2D structures, eventually resulting in a conductive oxide monolayer.     

Synthesis of Molybdenum Oxide by Thermal Decomposition of Molybdenum Acetylacetonate Sol-Gel

Synthesis of monophasic ultrafine molybdenum oxide at low temperatures by thermal decomposition of molybdenum acetylacetonate sol-gel is reported. The sol-gel is obtained through a solvent extraction technique from the organic solvent with the reduction in oxidation state of molybdenum. The thermal behaviour of the sol-gel is studied from the thermal analysis traces. The structural changes accompanying the thermal decomposition of the gel and the formation of monophasic molybdenum oxide is also reported with the help of X-ray diffraction and scanning electron microscopy techniques. This revised version was published online in August 2006 with corrections to the Cover Date.     

Electrically conductive nanocomposites with segregated structure based on poly(vinylidene fluoride-<Emphasis Type="Italic">co</Emphasis>-tetrafluoroethylene) and reduced graphene oxide

An approach was described to obtaining polymer composites with segregated structure that have high electrical conductivity at low concentrations of an electrically conductive filler. According to this approach, thin layers of electrically nonconductive nanodispersed graphene oxide are applied to the surface of polymer particles and conduction is produced by heat and chemical treatments. Hot pressing of the modified powder leads to combination of layers of the graphene-like filler to form a single electrically conductive network. For the first time, reduction of graphene oxide on the surface of polymer particles with hydrazine vapor at room temperature was performed. Comparison of the electrical conductivities of composites obtained by the thermal and chemical methods of graphene oxide reduction showed that the chemical reduction method gives composites with higher conductivities than the thermal method does. The maximum conductivity (0.5 S/m) was reached in a composite containing 0.6% chemically reduced graphene oxide.     

Synergistic effects between iron–graphene and melamine salt of pentaerythritol phosphate on flame retardant thermoplastic polyurethane

A comparison of melamine salt of pentaerythritol phosphate (MPP), and a synergistic agents, iron–graphene (IG) was performed in thermoplastic polyurethane (TPU) by masterbatch‐melt blending on thermal and flame retardant properties. The flame retardant properties of TPU composites were characterized by limiting oxygen index (LOI), UL 94 and cone calorimeter test (CCT). The CCT results revealed that IG can significantly enhance flame retardant properties of MPP in TPU. The peak heat release rate of neat TPU and flame retardant TPU/MPP composites decreased from 2192.6 and 226.7 to 187.2 kW/m² compared with that of TPU containing 0.25 wt% IG. The thermal stability and thermal decomposition of TPU composites were characterized by thermogravimetric analysis (TGA) and thermogravimetric/Fourier infrared spectrum analysis (TG‐IR). The results indicated IG and MPP can improve the thermal stability of TPU. The formation of thermal conductive network by IG can promote the decomposition of MPP into nonflammable melt, which can play the role of heat barrier and restrict the diffusion of fuels into combustion zone and access of oxygen to the unburned fuels. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal analysis of synthesis of wulfenite

A derivatograph was used in a thermal analysis study of the synthesis of wulfenite (lead molybdate) by the sintering of cerussite or lead oxide with molybdite. The reaction products were identified microscopically and by using a Siemens crystalloflex diffractometer. The DTA curves of mixtures of cerussite with molybdite show first the characteristic peaks of cerussite. The sharp endothermic peak at 300°C reflects the dehydration of hydrocerussite associated with cerussite. The endothermic peak at 350°C indicates the first step of cerussite decomposition, into PbO·PbCO₃, and that at 400°C indicates the second step of its decomposition, into lead oxide. The formation of wulfenite takes place at 520°C in an exothermic reaction. The medium endothermic peaks at 880 and 955°C reflect the melting and volatilization of unreacted lead and molybdenum oxides. The DTA curve of sintering of molybdite with lead oxide reveals the formation of wulfenite at 500°C. The melting and volatilization of unreacted lead and molybdenum oxides appear in only one large and sharp endothermic peak at 980°C.The resulting wulfenite is pale-yellow in thin section, and crystallizes in the tetragonal system, in the form of square tabular crystals, with distinct (011) cleavage.     

混合价黑色氧化铕的制备及其性质初步研究

用含肼甲酸铕在Ｎ２气氛中热分解的方法制得了混合价黑色氧化铕粉末。对它的有关物理化学性质进行了初步研究,得到了相应的结论。     

钼催化体系制备的聚1,2-丁二烯链结构

本文利用红外光谱、~(13)C-NMR和线膨胀等方法研究了钼体系聚1,2-丁二烯的链结构,并研究了链结构的调节方法。发现烯丙基卤等极性添加剂既可以调节1,2-链节含量,又可以调节链节的立体构型。最后,利用统计理论估计了1,2-链节的各种异构体的平均序列长度。     

Subject index

Thermal decomposition of an intimate mixture of thallium(I) perchlorate and chromium(III) oxide revealed that chromium(III) oxide lowers the decomposition temperature of thallium(I) perchlorate and is oxidized into hexavalent state to give thallium(I) dichromate. The thermal decomposition was followed by constant temperature heating, thermogravimetry and differential thermal analysis. The reaction products were characterized by chemical analysis, X-ray diffraction and infrared spectral measurements.     

富钙生物油煅烧过程中孔结构变化特性的研究

在热重分析仪上进行富钙生物油煅烧实验。结果表明,富钙生物油的煅烧过程分为三个阶段,分别是生物油部分组分的脱CO₂和H₂O阶段、有机酸钙盐分解阶段、碳酸钙分解阶段。其中,有机酸钙盐分解对煅烧产物的孔结构有重要影响。在450℃~600℃,气体析出的气蚀作用与生物油中高分子化合物的碳化沉积现象同时存在,两者共同作用,但后者占主导,高分子化合物的碳化沉积主要发生在500℃~600℃。600℃以后,碳酸钙开始分解,释放出CO₂,气蚀作用使煅烧产物内部形成新的微孔,产物具有发达的孔结构。相同煅烧温度下,富钙生物油煅烧产物的孔隙特性明显优于CaCO₃。     

Electrically conductive epoxy‐based nanocomposite adhesives loaded with silver‐coated copper and silver‐coated reduced graphene oxide nanoparticles

In this research, a conductive adhesive based on epoxy resin as the polymer matrix and silver‐coated copper powder and silver‐coated reduced graphene oxide as conductive fillers was synthesized. Graphene oxide was synthesized by modified Hummer's method. It was reduced and modified by silver powder. Copper particles were coated with silver using the electroless plating method. Finally, conductive nanocomposite adhesives were prepared using conductive fillers with different weight fractions. The structural properties of fillers were identified by Fourier‐transform infrared (FTIR) and induced coupled plasma (ICP) analysis and the morphology of the samples by scanning electron microscopy (SEM). Finally, conductive properties, lap shear strength, and thermal stability of adhesive were evaluated. The conductive adhesive prepared with optimized properties have 70% weight percentage silver‐coated copper powder and 1% weight percentage silver‐coated reduced graphene oxide. The bulk resistivity of the optimum sample was 1.6 × 10^‐2 Ω.cm, and the lap shear strength was 7.10 MPa. Also, thermogravimetric analysis showed that the weight loss of adhesive decreased from 88.72% to 30.55% during heating, which showed the addition of fillers improves the thermal stability of adhesive.     

Development of a reconversion method for uranyl nitrate to oxide in the reconversion step of reprocessing of irradiated fuel

Ammonium uranyl carbonate (AUC) precipitation is developed for the conversion of uranyl nitrate to oxide in the uranium reconversion step of reprocessing of irradiated fuel by the addition of ammonium carbonate salt. Different precipitation conditions of AUC are studied. The solubility of AUC as a function of uranium concentration in the feed at different temperatures using ammonium carbonate salt as precipitant is studied. This study indicates that 95-99.8% of uranium is recovered as AUC by precipitating 5-125 g/l of uranium with loss of uranium (250-10 ppm) in the filtrate by adding ammonium carbonate salt. It is also observed that the solubility of AUC increased as the concentration of uranium decreased. Thermal decomposition is carried out by thermogravimetry/differential thermal analysis (TG/DTA) and evolved gas analysis-mass spectrometry (EGA-MS) to find out AUC decomposition and gases evolved during decomposition. Studies are also carried out to characterize AUC by using X-ray diffraction (XRD). The data show that AUC obtained by the above conditions is very much consistent with published information.     

A study on Zn-based catal-sorbents for the simultaneous removal of hydrogen sulfide and ammonia at high temperature

To simultaneously remove hydrogen sulfide and ammonia from hot coal gases, the ammonia decomposition abilities of various metal oxide catalysts were tested in the absence/presence of hydrogen sulfide, at 650 °C. Cobalt oxide, molybdenum oxide, and nickel oxide have high ammonia decomposition abilities (>95%) in the absence of hydrogen sulfide, but such abilities rapidly decreased during the reaction in the presence of hydrogen sulfide. To improve the simultaneous removal abilities of metal oxides, Zn-based catal sorbents were prepared via impregnation with various metals, such as cobalt, nickel, and molybdenum, on zinc oxide. The CZ-30 (promoted with 30 wt% cobalt oxide on zinc oxide) and NZ-30 (promoted with 30 wt% nickel oxide on zinc oxide) catal sorbents showed excellent sulfur removal capacities, which, calculated until the breakthrough point, were 0.35 and 0.39 g S/g catal sorbent, respectively, while MZ-30 promoted with molybdenum showed a low sulfur removal capacity of 0.08 g S/g catal sorbent. The ammonia decomposition ability of CZ-30, however, increased more than 18 times compared with Co₃O₄, whose ammonia decomposition ability was more than 95% until 465 min, even though the ammonia decomposition ability of NZ-30 sharply decreased after 30 min. The CZ catal sorbent is a good candidate for the simultaneous removal of ammonia and hydrogen sulfide.     

Electrothermomechanical analysis and its application to studying electrically conductive adhesive joints

Electrothermomechanical analysis (ETMA) is effective for studying electrically conductive adhesive joints. Post curing of an electrically conductive adhesive (silver particle filled epoxy) by heating at an elevated temperature significantly enhances the thermal and mechanical stability of the conductive adhesive joint. The contact electrical resistivity and thickness of a joint tend to decrease cycle to cycle upon thermal cycling between 30 and 50°C and upon compression (up to 0.55 MPa). The effects of compression and thermal cycling are significant in the joint without post curing, but is insignificant after post curing. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of aerobic decomposition of Angeli's salt (sodium trioxodinitrate) at physiological pH

The recent determination that Angeli's salt may have clinical application as a nitrogen oxide donor for treatment of cardiovascular diseases such as heart failure has led to renewed interest in the mechanism and products of thermal decomposition of Angeli's salt under physiological conditions. In this report, several mechanisms are evaluated experimentally and by quantum mechanical calculations to determine whether HNO is in fact released from Angeli's salt in neutral, aerobic solution. The mechanism of product autoxidation is also considered.     

氧化铝薄膜表面羰基钼物种的可逆再生

 通过Mo(CO)6的热分解制备了Al2O3薄膜负载的金属钼模型催化剂,并采用热脱附谱(TDS)和X射线光电子能谱(XPS)原位研究了CO在金属态Mo/Al2O3模型催化剂表面的化学吸附. 结果表明,在低温下CO可与Al2O3表面的金属钼纳米粒子发生多重配位形成类似于羰基钼的物种. CO在Mo/Al2O3模型催化剂表面的吸附导致Mo 3d XPS峰向高结合能方向位移,所生成的羰基钼物种表现为TDS谱中在240 K处有脱附峰. 负载的金属钼模型表面与体相金属钼的化学性质完全不同,表现出明显的粒子尺寸效应.     

Structure Formation and Conduction of Nanosized Nickel Oxide in Porous Glass

Nickel(II) oxide was deposited on the surface of a porous glass in the amount of 0.5-7.0 mmol g^{- 1} by impregnation of the glass with an aqueous solutions of Ni(NO₃)₂, followed by decomposition of the salt at 673 K. The size features of the formation of the oxide structure were characterized by the data of optical and X-ray photoelectron spectroscopy and by measurements of density and electrical conductivity.     

Synthesis of nanocrystalline magnesium oxide by thermolysis of magnesium citrate

Magnesium citrate, obtained by dissolving magnesium oxide in an aqueous solution of citric acid, turned out to be a decahydrate of the composition Mg₃(C₆H₅O₇)₂·10H₂O, which was established by the results of synchronous thermal analysis, X-ray diffraction and IR spectroscopy. It is shown that the thermal decomposition of this salt proceeds in three stages in the temperature ranges of 120–250, 250–370 and 370–550 °C to form nanocrystalline magnesium oxide with grain sizes from 7 to 23 nm.     

Thermal Analysis and X-Ray Diffraction of Roasting of Egyptian Molybdenite

Molybdenite is the main ore mineral for the molybdenum industry and the production of molybdenum. The industrial processing of molybdenite is based on its oxidized roasting to technical grade molybdenum oxide, followed by its purification by distillation or its ammonia leaching.The present work reports a thermal analysis study of the oxidized roasting of Egyptian molybdenite, using a derivatograph. The reaction products were identified microscopically and by using a Siemens Crystalloflex diffractometer.The DTA curves of the roasting of molybdenite show that its oxidation begins at 360–370°C, as indicated by the small exothermic peak at such temperatures. This is followed immediately by a large, wide exothermic peak with maximum at 510–520°C, representing the intensive oxidation of molybdenite. The medium endothermic peak at 795–800°C reflects the melting and sublimation of molybdenum oxide. The vigourous vaporization of molybdenum oxide and its boiling are associated with the large, sharp endothermic peak at 1150°C. This is accompanied by a large loss in mass (TG).The study includes calculation of the thermodynamic constants and the kinetics of the reaction of oxidation of molybdenite.The oxidized roasting of molybdenite results in the production of molybdenum oxide, which is the essential starting material of the molybdenum industry. The molybdenum oxide produced has the molybdite structure and crystallizes in the orthorhombic system in the form of elongated, thin, light-green crystals.This revised version was published online in November 2005 with corrections to the Cover Date.     

Some studies on thallium oxalates. II. Thermal decomposition of potassium bisoxalato diaquothallate(III) dihydrate

Potassium bisoxalato diaquothallate(III) dihydrate is obtained by precipitating thallium(III) with oxalic acid from slightly acidic (HNO₃ or H₂SO₄) solutions in the presence of potassium ions. The thermal decomposition behaviour of the complex is studied using the techniques of TG, DTA and DTG. The solid complex salt and the intermediate products of its thermal decomposition are characterised using IR absorption spectra, microscopic observations, electrical conductivity measurements and X-ray diffraction data.