Studies on the synthesis and thermal decomposition mechanisms of rare-earth metal (Pr,Nd, Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one

Three new rare-earth metal (Pr, Nd and Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one (NTO) were prepared and characterized. The thermal behaviour of the three salt hydrates, M(NTO)₃·nH₂O (M=Pr and Nd,n=9;M=Sm,n=8) were studied by means of TG and DSC under conditions of linear temperature increase. The thermal decomposition intermediates were determined by means of IR, MS and X-ray diffraction spectrometry. The thermal decomposition mechanisms of these hydrates were proposed as follows: We express our thanks to Professor Zhu Chunhua, Associate Professor Fu Xiayun, and Lecturers Fan Tao and Liang Yanjun for their help in this work.     

介孔材料MCM-41上汽油吸附深度脱硫

 研究了不同硅铝比的MCM-41介孔材料作为吸附剂对模型汽油以及真实FCC汽油的脱硫性能. 结果表明,在室温和常压下,MCM-41介孔材料对模型溶液中噻吩的吸附随着吸附剂中铝含量的增加而显著提高. 吡啶吸附的红外光谱显示,噻吩吸附容量的提高与吸附材料酸性的明显增大有直接关系. 但在对FCC汽油的吸附脱硫实验中,随着MCM-41中铝含量的提高,脱硫率并未增大. 这主要是由于在FCC汽油中存在大量性质与噻吩类含硫化合物十分相近的芳烃和烯烃,竞争吸附导致MCM-41对有机硫化物的吸附能力显著降低.     

Fabrication and Electrochemical Behavior of Vanadium‐Substituted Keggin‐Type Polyoxometalates Multilayer Films on 4‐Aminobenzoic Acid Modified Glassy Carbon Electrodes

Two Vanadium‐substituted Keggin‐type polyoxometalates, K₃H₂[α‐SiVW₁₁O₄₀]?6H₂O (SiVW₁₁) and K₄H₂[γ(1, 2)‐SiV₂W₁₀O₄₀]?4H₂O (SiV₂W₁₀) were first successfully immobilized on 4‐aminobenzoic acid modified glass carbon electrodes respectively by layer‐by‐layer assembly with poly (ethylenimine) (PEI) as counterions. The regular growth processes were monitored by cyclic voltammetry (CV), and it was proved that the multilayer films were uniform and stable. The cyclic voltammetry results indicated that the electrochemical behavior of two multilayer films was similar, and their redox couples are pH‐ and scan rate‐dependent. The multilayer films show favorable electrocatalytic active toward the reduction of NO₂^?, IO₃^? and H₂O₂.     

Isotope Tracing Experiment on the Mechanism of O2 on the Over-Thermal Decomposition of SF6

In gas-insulated equipment, partial over-thermal faults may occur due to poor contact and other reasons. The main insulation medium SF₆ may decompose under over-thermal conditions and produce harmful products such as SO₂ and HF, which can damage the equipment and reduce the insulation strength of the equipment. The method of decomposition component analysis can monitor the operating status of equipment without interference from machinery, noise and optics, and provide early warning or reminder of faults, but the premise is that the decomposition mechanism of SF₆ must have been fully and in-depth understood. In the decomposition process of SF₆, O₂ has a significant effect, but the mechanism of the effect is still unclear. Based on the isotope tracing method, this paper uses ¹⁸O₂ instead of ordinary O₂ for overheating experiments. Through the quantitative detection of the labeled products in the product and the abundance of ¹⁸O isotope in the products, the effect of O₂ on the formation of the main decomposition products was analyzed. The work makes the reaction process and mechanism of SF₆ with trace oxygen under over-thermal conditions basically clear, which provides an important theoretical basis for on-line monitoring and fault diagnosis of equipment based on chemical analysis methods.

     

ZSM-35 分子筛的静态合成和晶化机理

 以环己胺为有机模板剂, 硅溶胶为硅源, 采用静态合成法在 220 ºC 的水热体系中制得了 ZSM-35 分子筛纯相. 当初始凝胶中含有一定量的 K+时, 在晶化过程中, K+与Na+的共同作用可以很好地抑制混晶丝光沸石的生成, 且当 n(K+)/n(K+ + Na+) = 0.3 时, 制得的 ZSM-35 分子筛晶化度最高. 利用 X 射线衍射和紫外拉曼光谱对分子筛形成的最佳条件以及晶化机理进行了研究. 发现合成初期前体中含有五元环和六元环的硅物种构筑单元. 通过水热晶化过程, 与硅酸盐的五元环或六元环有关的 450 cm–1 处紫外拉曼谱峰增强, 在晶化后期, 随着无定形凝胶逐渐被消耗, 在 421, 312 和 215 cm–1 处出现新的 ZSM-35 结构的特征拉曼谱峰, 说明这些环物种相互聚集最终形成了 ZSM-35 分子筛.     

多金属氧酸盐膜材料的研究

多金属氧酸盐膜材料在发光、光致变色、磁性、电性以及催化领域中有着广阔的发展前景,是多酸化学和材料化学领域的研究热点。本文综述了近年来多金属氧酸盐膜材料的研究现状及进展,总结了多金属氧酸盐膜材料的类型、成膜方法及性质,并对未来发展方向提出了一些看法。     

三吡啶胺Zn(Ⅱ)配合物作为碳酸酐酶模拟物的研究

利用pH电位滴定法，在25±0.1℃，I＝0.1mol·dm-3KNO3条件下，测定了三吡啶胺（TPA）的质子化常数和三吡啶胺Zn（II）配合物中配位水的解离常数.结果表明，该配合物中与Zn（II）配位的H2O分子的电离常数显著下降，测得pKa为7．8．在25±0．1℃，I＝0．1mol·dm－3NaClO4条件下，pH＝6～9（三羟甲基氨基甲烷缓冲溶液，20mmol·dm-3）范围内，用紫外-可见分光光度法考察了该配合物催化对硝基苯酚乙酸酯（NA）水解的动力学行为，得到了配合物催化酯水解的二级反应速率常数kNP，其最大值为3．32×10－2（mol·dm-3）-1·s－1热力学、动力学的研究结果均说明，三吡啶胺Zn（II）配合物中与Zn（II）配位的OH-是较好的亲核试剂，该配合物是一个较好的碳酸酐水解酶的模拟物．     

二次锂电池正极材料Li_xNi_（0．3）Co_（0．7）O_2的XPS与XRD

结果表明，ＬｉｘＮｉ０．３Ｃｏ０．７Ｏ２具有六方晶系Ｒ３－ｍ空间群结构。当Ｘ＝１，０．３１５时，其晶胞参数分别为ａ＝２．８２６ｎｍ，ｃ＝１４．１３０ｎｍ和ａ＝０．２８０８ｎｍ，ｃ＝１．４２５３ｎｍ；ＭＯ６（Ｍ＝Ｎｉ，Ｃｏ）八面体中Ｍ－Ｏ平均距离分别为０．１９４１ｎｍ和０．１９３３ｎｍ。ＸＰＳ分析结果表明ＬＩｘＮｉ０．３ＣＯ０．７Ｏ２表面存在Ｌｉ２Ｏ，同时探讨了其中过渡金属离子的３ｄ电子结构变化。     

链酚胺型配体锌(Ⅱ)配合物模拟碳酸酐酶研究

合成了酚胺型链状配体,N,N'-二(2-羟基苄基)丙二胺(H~2L)及其Zn(Ⅱ)配合物(ZnL),通过元素分析、IR和^1HNRM等手段进行了表征。采用pH电位滴定法,在25℃±0.1℃,I=0.1mol·dm^-^3(KNO~3)条件下,测定了配体的质子化常数以及配体与金属离子Zn(Ⅱ)配位反应平衡常数。讨论了配体与金属离子Zn(Ⅱ)的配位情况,得到了配位酚羟基的解离常数。运用分光光度法,在25℃±0.1℃,I=0.1mol·dm^-^3(KNO~3)条件下,在pH=5.5～9.0(50mmol·dm^-^3缓冲溶液)范围内,研究了配合物作为碳酸酐酶模拟物催化对-硝基苯酚乙酸酯(NA)水解动力学,得到了NA酯水解的配合物催化速率常数k~N~P。实验结果表明,ZnHL^+的配位酚羟基的解离常数pK~a为6.83;催化速率常数k~N~P与pH之间不存在Sigmoidal型曲线关系,而是在pH值中性附近有最大值,ZnHL^+对NA酯水解有很好的催化效果,并且采取双重催化机理,是碳酸酐酶很好的模拟物。     

Thermophysical properties of Ni-5%Sn alloy melt

The surface tension and specific heat of Ni-5%Sn alloy melt were measured by the oscillating drop method and the drop calorimetric method using electromagnetic levitation, respectively. The temperature coefficient of surface tension is 6.43×10⁻⁴ N·m⁻¹K⁻¹ within the temperature regime of 1464–1931 K. The enthalpy change was measured in the temperature range from 1461 to 1986 K, and the average specific heat was obtained as 43.03 J·mol⁻¹K⁻¹. Some other thermophysical properties, such as viscosity, solute diffusion coefficient, density, thermal diffusivity and thermal conductivity of this alloy melt, were derived based on the experimentally measured surface tension and specific heat. Using these thermophysical parameters, the relation between solute trapping and undercooling in rapidly solidified α-Ni was calculated, and the theoretical prediction shows a good agreement with experimental data.