碳前驱体CH3ArCH2NH2的热解性能及动力学研究

通过密闭压力容器法、常压DSC、高压DSC及紫外分光光度定量分析法等实验手段,对液相沉积法制碳／碳复合材料用碳前驱体CH3ArCH2NH2的热裂解行为进行了研究,获得不同温度、不同压力下该碳前驱体的热分解温度和残碳率,用等温动力学和非等温动力学方法获得了热裂解反应的表观活化能,实验结果表明,常压热裂解温度大约为530．15－556．55K,1－3MPa的高压范围内的热裂解温度大约在618．34－675．49K,密闭压力容器中的残碳率为56．23％,常压下的残碳率为28．96％－36．47％,而高压下残碳率可达59．11％,根据基辛格等方法获得了等温条件下和非等温条件下热裂解反应的表观活化能Ea分别为206．78kJ/mol和183．93kJ/mol, 反应级数N~1.     

碳碳偶合反应中间体Li[Cp2Zr(C≡CPh)·(η2∶1,2-PhC2C≡CPh)]的合成和晶体结构

室温下,用Cp2ZrCl2与LiC≡CPh反应,合成了碳碳偶合反应的Zr(Ⅱ)阴离子中间体Li[Cp2Zr(C≡CPh)(η2:1,2-PhC2C≡CPh)].用元素分析、核磁共振谱和红外光谱对配合物进行了表征,配合物的晶体结构分析给出了两个炔烃之间碳碳偶合的证据.用核磁共振谱初步探讨了合成反应机理.     

花状Zn-MOF衍生碳@MoS2复合材料制备及吸波性能

采用Zn-MOF(MOF为金属有机骨架)制备纳米多孔碳材料,通过自组装法将多孔碳与花状MoS₂结合,制备出具有规整有序结构的花状Zn-MOF衍生碳@MoS₂复合吸波材料。基于Zn-MOF衍生纳米多孔碳的高孔隙率、大比表面积,MoS₂的花状结构引起的电磁波多次反射和散射,以及MoS₂和Zn-MOF衍生碳之间存在的强极化效应、良好的阻抗匹配和协同作用,Zn-MOF衍生碳@MoS₂在频率为9.28 GHz时的最佳反射损耗达到-49.68 dB,表现出优异的电磁波吸收性能。     

铈基复合氧化物催化碳烟燃烧的性能及其H2-TPR研究

采用溶胶-凝胶法或浸渍法制备了不同金属离子掺杂的铈基复合氧化物催化剂,并采用热重法考察其催化碳烟燃烧的活性,借助H₂-TPR(程序升温还原)手段探讨了催化剂氧化还原性对碳烟燃烧性能的影响. 结果表明,过渡金属的掺杂促使催化剂在低温下提供更多的表面氧和晶格氧,显著降低了碳烟的氧化温度,催化剂于200~400℃释放的活性氧数量对于碳烟燃烧性能提高至关重要; 而结构性助剂金属、碱金属或碱土金属的掺入可提高中温活性氧数量,虽然对碳烟起燃温度无明显改善,但加快了碳烟的燃烧速率.     

g-C3N4/Bi2O2CO32D纳米片复合材料的制备及可见光催化性能研究

采用自组装和化学沉淀法分别制得两种可见光驱动复合材料石墨相氮化碳/碳酸氧铋(g-C_3N_4/Bi_2O_2CO_3).采用X射线衍射光谱(XRD),紫外可见光谱、扫描电镜(SEM)、N_2吸附、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,制备方法对纳米复合材料的晶相、形态及光学性能没有影响,但是影响g-C_3N_4和Bi_2O_2CO_3之间的相互作用力,导致光生电子-空穴对的分离速率存在显著差异.以可见光驱动苯酚和罗丹明B的降解实验为探针反应检测催化剂的光催化性能.实验结果表明自组装法得到的异质结催化剂中相互作用力更强,催化效果最高.O_2-是罗丹明B降解反应的主要活性物种,染料的光敏化、Bi_2O_2CO_3与g-C_3N_4综合效应,导致光生载流子电荷分离效率更高.     

RGO/g-C3N4/MoS2复合材料的制备及其光催化性能

通过热解-水热两步法制备了石墨烯/石墨相氮化碳/二硫化钼(RGO/g-C_3N_4/MoS_2)复合材料并使用多种分析表征手段对RGO/g-C_3N_4/MoS_2的结构、形貌及光催化性能进行分析。结果表明,具有异质结构的g-C_3N_4/MoS_2与RGO复合后,通过良好的界面接触和电荷的快速转移,增强了其光生电子-空穴的分离。经可见光照射120 min后,RGO/g-C_3N_4/MoS_2复合材料可降解97%亚甲基蓝。此外,循环实验表明RGO/g-C_3N_4/MoS_2复合材料具有良好的稳定性,经5次循环仍能保持93.2%的光催化活性。     

一步热聚合法制备Cu2O/CuO-g-C3N4吸附剂及其对甲基橙吸附的性能

用一步热聚合法制备了一种铜改性的石墨氮化碳吸附剂,并研究了其对甲基橙的吸附性能。以氧化亚铜、双氰胺为前驱体,以氯化胺作为气体模板,在高温下引发聚合获得了铜改性的石墨氮化碳吸附剂(Cu₂O/CuO-g-C₃N₄)。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)及全自动比表面及孔隙度分析(BET)等对所制备吸附剂的组成和结构进行了表征,结果表明,该吸附剂由Cu、C、N和O共4种元素组成具有介孔结构的层状材料。引入铜氧化物以后,有效地扩展了g-C₃N₄的π共轭体系,有利于通过π-π作用吸附带有苯环结构的染料;Cu₂O/CuO-g-C₃N₄吸附剂具有多种孔径的介孔结构增大了其比表面积,为染料的吸附提供了足够的活性位点。通过优化吸附剂的制备条件、投加量、染料浓度、吸附时间、搅拌转速和pH等参数后,获得在最优条件下对甲基橙溶液的吸附率仅需25 min即可达到96.11%。进一步地,在常温常压下...     

密封石英管爆裂法快速分析包裹体中CO2碳同位素

传统的包裹体中CO2碳同位素制备分析方法,通常是在真空条件的管式加热炉中对样品进行加热爆裂,进而释放包裹体中的CO2,并对其进行提取纯化,测定碳的同位素组成。本实验建立了密封石英管爆裂法:将包裹体样品在真空条件下密封在单个的石英样品管中进行加热爆裂,进而收集纯化CO2气体,再对其进行碳同位素分析测试。密封石英管爆裂法能够获得高精度的碳同位素分析数据(1s=0.04‰)。对于包裹体样品(IGGZhu)的CO2碳同位素分析结果虽然具有较大的分布范围(!3.6‰~!6‰),但其反映的是多期次包裹体混合的结果。另外,由于包裹体样品可以集中批次统一爆裂,简化了操作流程,提高了实验测试效率。单个石英样品管也避免了样品之间的污染问题。     

有序介孔CuFe2O4同时催化去除碳烟与NOx

采用纳米复刻(浇筑)法制备一系列介孔CuFe_2O_4.通过X射线衍射(XRD)、 N_2物理吸附、透射电镜(TEM)等研究了不同制备条件对有序介孔CuFe_2O_4结构形成的影响.研究发现,作为对比,柠檬酸法仅能合成普通的四方相CuFe_2O_4纳米颗粒,但是硬模板法则能合成出高温淬火才能形成的立方晶相介孔结构CuFe_2O_4.进一步研究了该催化剂同时催化去除碳烟和氮氧化合物(NO_x)的性能,研究发现,与柠檬酸法合成的普通CuFe_2O_4催化剂相比,介孔结构CuFe_2O_4不仅大幅降低了碳烟起燃温度(324降低到278℃),而且将N_2的最高产率从5.9%提升到了92.2%.基于原位漫反射红外(in-situ DRIFTS)的机理分析研究表明,合成过程中采用NaOH除去硬模板的过程中会在介孔CuFe_2O_4表面造成大量残留的钠盐,这种高分散的钠物种促进了NO_x的吸附并转化为硝酸盐物种,从而促进碳烟氧化以及NO_x转化.但是与表面Na修饰的CuFe_2O_4相比,体相Na掺杂的CuFe_2O_4虽然具有更好的有序介孔结构,但是其氧化性能下降,进一步也导致了NO_x的催化还原性能的下降.     

碳包覆Li3V2(PO4)3:溶胶-凝胶法合成及性能

利用V₂O₅、LiOH·H₂O、H₂O₂、NH₄H₂PO₄与柠檬酸为原料,通过溶胶-凝胶法合成了碳包覆的Li₃V₂(PO₄)₃复合正极材料。采用XPS、XRD、SEM、TEM、拉曼光谱和电化学方法对材料的性能进行了研究。还研究了其结构与焙烧温度、样品电导率和电化学性能的关系。研究表明复合材料具有空间群为P2₁/n的单斜结构,表面包覆粗糙多孔的碳层。在800 ℃下制备的碳包覆样品的电子导电率高达9.81×10^-5 S·cm^-1,约为高温固相氢气还原法制备的未包覆碳Li₃V₂(PO₄)₃的10000倍。测试结果表明碳包覆Li₃V₂(PO₄)₃的电化学性能远优于未包覆碳的样品。在3.0～4.3 V电压范围内,以0.1C和2C倍率充放电时,碳包覆的Li₃V₂(PO₄)₃具有高比容量(分别为128和109 mAh·g^-1)和优异的循环性能。     

KCl-KBO2-K2CO3, K2MoO4-KBO2-K2CO3, and K2WO4-KBO2-K2CO3 ternary systems

phase diagrams of KCl-KBO₂-K₂CO₃, K₂MoO₄-KBO₂-K₂CO₃, and K₂WO₄-KBO₂-K₂CO₃ ternary systems were studied by a calculation-experimental method and differential thermal analysis (DTA). The coordinates of ternary eutectics were determined to be E ₁: 622°C, 8.5 mol % KBO₂, 56.5 mol % KCl, and 35 mol % K₂CO₃; E ₂: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂MoO₄; E ₃: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂WO₄. The specific heats of melting of the eutectics were determined.     

Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O system

Solubility in the Na₂Cr₂O₇-(NH₄)₂Cr₂O₇-K₂Cr₂O₇-H₂O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.     

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…     

The preparation of NbH5(Me2PCH2CH2Me2)2 and NbHL2(Me2PCH2CH2PMe2)2 (L = CO or C2H4)

MMe₅(dmpe) (M = Nb or Ta, dmpe = Me₂PCH₂CH₂PMe₂) reacts with H₂ (500 atm) and dmpe in THF at 60°C to give MH₅(dmpe)_2? NbH₅(dmpe)₂ readily reacts with two mol of CO or ethylene (L) to give NbHL₂(dmpe)₂. The exchange of the hydride ligand with the ethylene protons in NbH(C₂H₄)₂(dmpe)₂ is not rapid on the ¹H NMR time scale (60 MHz) at 95°C.     

Li2SO4-Na2SO4-H2O和Li2SO4- K2SO4-H2O溶液的体积性质

本文用高精度数字式振荡管密度计测定了288K至318K温度范围内Li₂SO₄ + Na₂SO₄ + H₂O和 Li₂SO₄ + K₂SO₄ + H₂O三元体系的密度。混合溶液的离子强度范围从0.1到4.5 mol.kg_–1,混合溶液中Na₂SO₄和K₂SO₄的离子强度分数为0.2,0.4,0.6和0.8。用密度实验值拟合得到了不同温度下Pitzer离子相互作用模型混合参数θ_V和 ψ_V,模型的计算值与实验值的偏差在±0.002 g.cm_–3以内。用Pitzer模型计算了不同离子强度下三元体系的混合体积。     

NaBO2-NaCl-Na2CO3, NaBO2- Na2CO3-NaMoO4, NaBO2- Na2CO3-NaWO4, and NaBO2-NaCl-Na2WO4 ternary systems

The phase diagrams of the NaBO₂-NaCl-Na₂CO₃, NaBO₂-Na₂CO₃-Na₂MoO₄, NaBO₂- Na₂CO₃-Na₂WO₄, and NaBO₂-NaCl-Na₂WO₄ ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary eutectics were determined: E ₁: 612°C, 16 mol % NaBO₂, 42 mol % NaCl, and 42 mol % Na₂CO₃; E ₂: 568°C, 12 mol % NaBO₂, 28 mol % Na₂CO₃, and 60 mol % Na₂MoO₄; E ₃: 575°C, 12 mol % NaBO₂, 32 mol % Na₂CO₃, and 56 mol % Na₂WO₄; E ₄: 628°C, 8 mol % NaBO₂, 20 mol % NaCl, and 72 mol % Na₂WO₄; and E ₅: 655°C, 9 mol % NaBO₂, 53 mol % NaCl, and 38 mol % Na₂WO₄.     

Ag2Se-Tl2Se-Bi2Se3 quasi-ternary system

The Ag₂Se-Tl₂Se-Bi₂Se₃ quasi-ternary system (system A) was studied using DTA, X-ray powder diffraction, microstructure examination, and microhardness measurements. TlBiSe₂-AgBiSe₂, AgTlSe-AgBiSe₂, AgTlSe-Bi₂Se₃, and Tl₂Se-AgBiSe₂ polytherms, isothermal sections at 500 and 800 K, and liquidus surface projection of system A were constructed. System A is congruently triangulated into the following subordinate triangles: Tl₂Se-AgTlSe-Tl₉BiSe₆ (I), AgTlSe-Tl₉BiSe₆-TlBiSe₂ (II), Ag₂Se-AgTlSe-TlBiSe₂ (III), Ag₂Se-AgBiSe₂-TlBiSe₂ (IV), and AgBiSe₂-TlBiSe₂-Bi₂Se₃ (V). Subsystems I, III, and V are ternary systems with three-phase eutectic equilibrium; system II has a three-phase eutectic, and system IV is characterized by several invariant and monovariant peritectic and eutectic equilibria. Primary crystallization and homogeneity fields were outlined, and the types and coordinates of invariant and monovariant equilibria in system A were determined. A characteristic feature of the title system is an extensive field of solid solutions between high-temperature cubic AgBiSe₂ and TlBiSe₂ phases; this field lies as a continuous belt along the AgBiSe₂-TlBiSe₂ quasibinary section and covers about one-fourth of the surface area of the triangular diagram of system A.     

Polymorphism in the Sc2Si2O7-Y2Si2O7 system

This paper examines the structural changes with temperature and composition in the Sc₂Si₂O₇-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 Y₂O₃ and Sc₂O₃ mixtures. A set of different compositions have been synthesized using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1750 °C during different times. 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 very reduced stability fields. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of the components. Although, the XRD data show a complete solid solubility of β-Sc₂Si₂O₇ in β-Y₂Si₂O₇ at 1300 °C, the ²⁹Si MAS-NMR spectra indicate a local structural change at x ca. 1.15 (Sc_2−xY_xSi₂O₇) related to the configuration of the Si tetrahedron, which does not affect the long-range order of the β-RE₂Si₂O₇ structure. Finally, it is interesting to note that, although Sc₂Si₂O₇ shows a unique stable polymorph (β), Sc³⁺ is able to replace Y³⁺ in γ-Y₂Si₂O₇ in the compositional range 1.86?x?2 (where x is Sc_2−xY_xSi₂O₇) as well as in δ-Y₂Si₂O₇ for compositions much closer to the pure Y₂Si₂O₇.     

Synthesis and characterization of inorganic solid electrolytes of Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 systems

The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li₂O-SiO₂-P₂O₅ and Li₂O-TiO₂-SiO₂-P₂O₅ were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10⁻⁴ S/cm in the Li₂O-TiO₂-SiO₂-P₂O₅ system. Original Russian Text ? W. Li, M. Wang, Z.H. Li, X.F. Shang, H. Wang, Y.W. Wang, Y.B. Xu, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 11, pp. 1341–1345.     

(H2NC4H8NCH2CH2NH2)(HNCH2CH2NH2)3Zn2Ge2Se8: A new,templated one-dimensional ternary semiconductor stabilized by mixed organic cations

The novel, 1D semiconductor (H₂NC₄H₈NCH₂CH₂NH₂)(HNCH₂CH₂NH₂)₃Zn₂Ge₂Se₈ has been synthesized under solvothermal conditions using N-(2-aminoethyl)piperazine as solvent and templating agent at 200 °C. The material was characterized by single crystal and powder X-ray diffraction, IR and Raman spectroscopy and thermogravimetric analysis. The compound consists of 1D anionic [Zn₂Ge₂Se₈]⁴⁻ chains made of alternating edge-shared [ZnSe₄] and [GeSe₄] tetrahedra that charged balanced by one N-(2-aminoethyl)piperazinium and three piperazinium cations. The optical properties were investigated with solid state UV–Vis/near IR spectroscopy and the results show that the solid is a medium gap semiconductor with an absorption edge at 1.8 eV.