Study of the solubility of components in the NaClO3 · 2CO(NH2)2-NH2C2H4OH · CH3COOH-H2O system

The solubility of components in the NaClO₃ · 2CO(NH₂)₂-NH₂C₂H₄OH · CH₃COOH-H₂O system was studied by the visual polythermal method over wide temperature and concentration ranges. In the phase diagram, crystallization fields were determined for ice, urea, diurea sodium chlorate, acetic acid, monoethanolamine acetate, and the compound CO(NH₂)₂ · NH₂C₂H₄OH · CH₃COOH. The compound was identified by chemical, thermogravimetric, and X-ray powder diffraction analyses.     

Study of Dehydrocoupling Reactions of Diorganotin Dihydrides R1R2SnH2 with Biuret

phenylmethyltin dihydride (PhMeSnH₂), phenylethyltin dihydride (PhEtSnH₂), phenylbutyltin dihydride (PhBuSnH₂) and butylmethyltin dihydride (BuMeSnH₂) with biuret (H₂L) proceeds via SnH/NH dehydrocoupling to afford the corresponding tetra-coordinate cyclic products. The reactions in the molar ratios of 1∶1, 2∶1 and 1∶2 have been studied. The yellow derivatives so isolated were soluble in polar solvents and insoluble in nonpolar solvents. It was found that 1∶1 reaction went to completion while 2∶1 and 1∶2 did not go to completion. The derivatives had been characterized by elemental analysis and spectroscopic techniques viz. IR, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR. DSC and TGA of the reaction products have also been studied. All the derivatives were thermally stable upto (190±10) ℃ and degradation occurred after that.     

Rotational Analysis of A2Πu-X2Σ+g System of 14N2+

The absorption spectrum of N₂⁺ has been studied using optical-heterodyne velocity mod-ulation spectroscopy in the near-infrared region. The observed spectral lines were assigned to the (3,1), (4,2), (5,3), (8,5) bands of the A²Π_u-X²Σ⁺_g system and the line lists were provided. The (5,3) band was studied for the first time. Fourteen rotational-resolved bands in literatures were fitted together with our observed bands and the molecular constants were obtained for υ_A=0-9 and υ_X=0-5.     

Effect of the Nature of Second-Sphere Cation on the Architecture of Crystalline π-Complexes Ca[CuCl2(HOCH2C≡CCH2OH)]2.4H2O and (C7H5N2H2)[CuCl2(HOCH2C≡CCH2OH)]

In the MCl-CuCl-HOCH₂C≡CCH₂OH (M = Ca, C₇H₅N₂H₊²) system, the crystals of two anionic Ca[CuCl₂(HOCH₂C≡CCH₂OH)]₂-4H₂O (1) and (BimH)[CuCl₂(HOCH₂C≡CCH₂OH)] (2) (BimH⁺ is cation of benzimidazole-C₇H₅N₂H₊²) π-complexes are obtained and studied by single crystal X-ray diffraction Crystals of 1 are monoclinic: C2/c space group, a = 8.323(3) ?, b = 13.283(4) ?, c = 16.741(5) ?, β = 92.35(3)°, V = 1849.3(10) ?³, Z = 4; crystals of 2 are triclinic: P1 space group, a = 6.901(3) ?, b = 9.898(4)?, c = 9.987(4) ?, α = 94.91(3)°, β = 93.91(3)°, γ = 107.59(4)°, V = 644.7(5) ?³, Z = 2. Complex 1 consists of infinite bimetallic chains [Ca(H₂O)₄CuCl₂(HOCH₂C≡CCH₂OH)₂]_∞ forming a three-dimensional framework through (Ow)HCl and (C)O-HCl hydrogen bonds. Compound 2 is built from discrete anions [CuCl₂(HOCH₂C≡CCH₂OH)]^- paired by edge-to-edge packing in the [100] direction and large BimH⁺ cations with face-to-face packing. In both structures, the π-coordinated Cu(I) atom has the trigonal environment involving two Cl^- anions and C≡C 2-butyne-1,4-diol bond (Cu-(C≡C) distance is 1.918(2) ? and 1.910(4) ? for 1 and 2 respectively).     

Oxidative coupling of methane over Bi2O3?P2O5?K2O/Sm2O3

Oxidative coupling of methane over Bi₂O₃–P₂O₅–K₂O/Sm₂O₃ takes place giving more C₂H₄ as compared to C₂H₆. Sm₂O₃ supported Bi–P–K is a more active and selective catalyst, than TiO₂, -Al₂O₃, SiO₂ and MgO supported catalysts.

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Bi₂O₃–P₂O₅–K₂O/Sm₂O₃ , . Bi–P–K, Sm₂O₃, , TiO₂, -Al₂O₃, SiO₂, MgO.

     

Hydrogenation of 2-ethylanthraquinone over Pd/Zro2-γ-Al2O3 catalyst

A ZrO₂-γ-Al₂O₃ supported Pd catalyst was prepared and characterized by XRD, XPS, H₂-TPR and TEM techniques. The catalytic activity was evaluated in the liquid-phase hydrogenation of 2-ethylanthraquinone. Comparing with Pd/γ-Al₂O₃, it showed high catalytic activity.     

Dehydrogenation of Isobutane Over V2O5/γ-Al2O3 Catalyst

The effect of the type of the support and the amount of V₂O₅ loading on the activity of V₂O₅/γ-Al₂O₃ catalyst for the dehydrogenation of isobutane have been investigated. Based on the experimental results of TPR, XRD and ESR spectroscopy, it is suggested that there are strong interactions between vanadia and carrier and that the V⁴⁺ species on the surface is the active site of V₂O₅/γ-Al₂O₃ for this reaction. This revised version was published online in June 2006 with corrections to the Cover Date.     

Kinetic simulation of oxidative dehydrogenation of n-butenes over SnO2?Sb2O4 catalysts

A previously suggested reaction mechanism was utilized to evaluate a kinetic model for the oxidation of n-butenes over ShSb=31 mixed oxide catalyst. With this model, kinetic curves measured at 673 K were simulated, illustrating the changes of amounts of undetectable surface components, too.

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- SnSb=31 . , 673 K, .

     

Solid solubility of Yb2Si2O7 in β-, γ- and δ-Y2Si2O7

This paper examines the structural changes with temperature and composition in the Yb₂Si₂O₇-Y₂Si₂O₇ system; members of this system are expected to form in the intergranular region of Si₃N₄ and SiC structural ceramics when sintered with the aid of Yb₂O₃ and Y₂O₃ mixtures. A set of different compositions have been synthesised using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1650 °C during different times. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of Yb₂Si₂O₇ in β-Y₂Si₂O₇ and γ-Y₂Si₂O₇. Although Yb₂Si₂O₇ shows a unique stable polymorph (β), Yb³⁺ is able to replace Y³⁺ in γ-Y₂Si₂O₇ and δ-Y₂Si₂O₇ at high temperatures and low Yb contents. IR results confirm the total solid solubility in the system and suggest a constant SiOSi angle of 180° in the Si₂O₇ unit across the system. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β-RE₂Si₂O₇ polymorph, with γ-RE₂Si₂O₇ and δ-RE₂Si₂O₇ showing reduced stability fields. The diagram is in accordance with Felsche's diagram if average ionic radii are assumed for the members of the solid solution at any temperature, as long as the β-γ phase boundary is slightly shifted towards higher radii.     

Influence of γ-radiation on the reactivity of montmorillonite towards H2O2

Compacted and water saturated bentonite will be used as an engineered barrier in deep geological repositories for radioactive waste in many countries. Due to the high dose rate of ionizing radiation outside the canisters holding the nuclear waste, radiolysis of the interlayer and pore water in the compacted bentonite is unavoidable. Upon reaction with the oxidizing and reducing species formed by water radiolysis (OH^•, e⁻_(aq), H^•, H₂O₂, H₂, HO₂^•, H₃O⁺), the overall redox properties in the bentonite barrier may change. In this study the influence of γ-radiation on the structural Fe(II)/Fe_Tot ratio in montmorillonite and its reactivity towards hydrogen peroxide (H₂O₂) was investigated in parallel experiments. The results show that under anoxic conditions the structural Fe(II)/Fe_Tot ratio of dispersed Montmorillonite increased from ≤3 to 25-30% after γ-doses comparable to repository conditions. Furthermore, a strong correlation between the structural Fe(II)/Fe_Tot ratio and the H₂O₂ decomposition rate in montmorillonite dispersions was found. This correlation was further verified in experiments with consecutive H₂O₂ additions, since the structural Fe(II)/Fe_Tot ratio was seen to decrease concordantly. This work shows that the structural iron in montmorillonite could be a sink for one of the major oxidants formed upon water radiolysis in the bentonite barrier, H₂O₂.     

Hydroisomerization of benzene-containing gasoline fractions on a Pt/SO 42? -ZrO2-Al2O3 catalyst: I. Effect of chemical composition on the phase state and texture characteristics of SO 42? -ZrO2-Al2O3 supports

A series of SO₄²⁻-ZrO₂-Al₂O₃ oxide supports containing from 18.8 to 89.1 wt % alumina was prepared by mixing sulfated zirconia hydrate (weight ratio ZrO₂: H₂SO₄ = 9 : 1) and pseudoboehmite followed by calcination at 650°C. For the subsequent use of the supports to optimize the acid and hydrogenating properties of bifunctional hydroisomerization catalysts of the Pt/SO₄²⁻-ZrO₂-Al₂O₃ type, the formation of these catalysts in the course of thermal treatment and their texture characteristics and phase composition were studied. It was found by chemical and thermogravimetric analysis that the addition of pseudoboehmite to sulfated zirconia hydrate resulted in a decrease in sulfur losses in the course of support production from 55.0 to 2.0% with respect to its nominal amount. As the alumina content was increased from 18.8 to 89.1 wt %, the specific surface area and the pore volume of the support increased nonadditively with respect to mechanical mixtures of sulfated zirconia and γ-alumina (from 155 to 197 m²/g and from 0.24 to 0.52 cm³/g, respectively); in this case, a maximum deviation was 18–21%. The experimental results can be explained by chemical interactions between the initial components of the supports. The results of thermogravimetric and X-ray diffraction analysis suggest that the reaction products are sulfated alumina and a sulfated ZrO₂-Al₂O₃ solid solution.     

Ab-initio structure determination of β-La2WO6

The structure of the low-temperature form of β-La₂WO₆ has been determined from laboratory X-ray, neutron time-of-flight and electron diffraction data. This tungstate crystallizes in the non-centrosymmetric orthorhombic space group (no. 19) P2₁2₁2₁, with Z=8, a=7.5196(1) Å, b=10.3476(1) Å, c=12.7944(2) Å, and a measured density 7.37(1) g cm⁻³. The structure consists of tungsten [WO₆] octahedra and tetrahedral [OLa₄]. Tungsten polyhedra are connected such that [W₂O₁₁]¹⁰⁻ units are formed.     

Highly efficient utilization of H2O2 for oxygenation of organic sulfides catalyzed by [γ-SiW10O34(H2O)2]

Remarkable efficiency of hydrogen peroxide utilization is reported for oxygenation of four organic sulfides catalyzed by a divacant lacunary silicotungstate, (Bu₄N)₄[γ-SiW₁₀O₃₄(H₂O)₂] (1), under mild conditions. The addition of imidazole, phosphate, or carboxylates significantly enhances the rate of organic sulfide oxygenation. Most notably, use of 1 and imidazole, both at 1% molar concentration, resulted in the quantitative conversion of phenylsulfide to sulfoxide with 1 equiv of H₂O₂ in 3 h, and to sulfone with 2 equiv of H₂O₂ in 6 h.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Role of support nature （γ-Al2O3 and SiO2-Al2O3） on the performances of rhenium oxide catalysts in the metathesis of ethylene and 2-pentene

The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re2O7/γ-Al2O3 and Re2O7/SiO2-Al2O3 catalysts. Both NH3 temperature-programmed desorption (NH3-TPD) and H2 temperature-programmed reduction (H2-TPR) results showed that Re2O7/SiO2-Al2O3 exhibited stronger acidity and weaker metal-support interaction than Re2O7/γ-Al2O3. At 35 60℃, isomerization free metathesis was observed only over Re2O7/γ-Al2O3, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re2O7/SiO2-Al2O3, hydrido-rhenium species ([Re]-H) were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.     

[(NH2CH2CH2NH3)2WⅥO2(NHC6H4NH)2]2(NH2CH2CH2NH2)·H2O配合物的合成与晶体结构

Cis-dioxo-tungsten(Ⅵ) complex, (NH₂CH₂CH₂NH₂)[(NH₂CH₂CH₂NH₃)₂W^ⅥO₂(NHC₆H₄NH)₂]₂·H₂O is synthesized at room temperature by the reaction of sodium tungstate with o-phenylenediamine. The crystal structure of complex was determined by X-ray diffraction structural analysis. The results show that complex belongs to monoclinic system with space group P2₁/ c, a=0.712 8(2) nm, b=3.081 1(10) nm, c=0.981 9(3) nm, β=102.615(4)°, V=2.104 4(11) nm³, Z=2, μ=55.26 cm^-1, F(000)=1 176. Compared the complex with its analogous biomimetic complexes of the cofactor of molybdoenzymes and tungstoenzymses, it is found that the variance of the coordination atoms and the metal ions center have no influence on the coordination feature, and exhibits distored octahedral coordination with cis-dioxo o-phenylenediamine. CCDC: 252834.     

Enthalpies of solution and standard enthalpy of formation of crystalline NaVO3 · 2H2O

The enthalpies of solution of sodium metavanadate dihydrate in aqueous solutions of sodium perchlorate at ionic strength I = 0.3, 0.5, and 1.0 mol/L were calorimetrically measured at 298.15 K. The resulting experimental data were used to calculate the standard enthalpy of formation of crystalline NaVO₃ · 2H₂O.     

Methanation of CO2 over Ru?SiO2 catalyst

Using Ru–SiO₂ catalyst, the kinetics of methanation of carbon dioxide has been studied. In the temperature range of 320–460°C a simple power law model is found to predict experimental results with a good agreement over the range of variables studied.

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Ru/SiO₂. , 320–460°C.

     

新型层状磷酸铝[Al6P8O32][(C2H5)2NHCH2CH2NH3]2·[C2H5NH2CH2CH2NH2C2H5] 的合成、表征及其共模板作用

在溶剂热体系中,以N,N-二乙基乙二胺为结构导向剂,合成了Al/P为3/4的层状磷酸铝[Al6P8O32][(C2H5)2NHCH2CH2NH3]2·[C2H5NH2CH2CH2NH2C2H5]单晶,并通过X射线单晶衍射结构分析.XRD,ICP,元素分析,差热-热重分析等手段进行了表征.该化合物属单斜晶系,P2(1)/c空间群,晶胞参数:a=0.90945(2)nm,b=1.46424(4)nm,c=1.87572(5)nm,β=102.672(2)°,Z=4.其阴离子层由AlO4四面体和PO3(=O)四面体单元交替连接构成,形成四、六、八元环拓扑结构,无机层以ABAB方式堆积,两种质子化的有机胺分子N,N-二乙基乙二胺及其重排产物N,N′-二乙基乙二胺填充在层间.用分子动力学模拟方法,考察了标题化合物中有机胺与无机层间的相互作用,讨论了这两种有机胺的共模板作用.