锂离子电池负极材料Li4Ti5O12的研究进展

"零应变"材料Li4Ti5O12具有优良的循环性能和平稳的放电电压等优点,与石墨电极相比,其安全性和使用寿命都大大提高.本文介绍了锂离子电池负极材料Li4Ti5O12的结构与性能,总结了制备方法、制备工艺参数对其性能的影响,对Li4Ti5O12的掺杂改性作了综述,并对Li4Ti5O12性能提高的发展方向作了展望.     

四氟苯菊酯的合成

以四氯对苯二甲氰为原料,经过氟化、水解、脱羧、酰氯化、还原5步反应合成四氟苄醇,再与二氯菊酰氯缩合得四氟苯菊酯。反应总收率在39％以上,含量达93％。     

2-氯-5-三氟甲基吡啶的合成

以氯化苄为原料,经过5步反应合成2-氯-5-三氟甲基吡啶.实验考察了反应条件对合成反应的影响,产品总收率达到37.4%.     

SiCp/Al基复合材料制备工艺的优化

本文利用热压烧结技术制备了性能优良的SiCp5vol%Al基复合材料,利用正交实验对参数进行了优化。结果表明,SiCp5vol%Al基复合材料的最佳工艺参数为烧结温度600℃、高温压力70MPa、保压时间7min。     

3-硝基-1,2,4-三唑-5-酮及其盐的研究概述

详细介绍了新型含能材料3-硝基-1,2,4-三唑-5-酮（NTO）的合成与性能研究状况,包括合成方法、晶体结构、量子化学、热分解行为、毒性等方面。着重介绍了包括NTO碱金属、碱土金属、过渡金属和稀土金属等21种NTO金属盐的单晶结构和热行为,重点总结了NTO碱金属盐的热分解产物,其中NTO的锂、钠、钾配合物的最终分解产物为碳酸盐,而铷和铯配合物的最终分解产物为碳酸盐、氧化物和高聚物,得出NTO碱金属盐的活化焓（△H≠）和放热分解峰温（Tpdo）之间的关系。附参考文献73篇。     

浅述毒死蜱的合成

介绍了毒死蜱及其中间体三氯吡啶酚合成路线及方法,并对其合成路线进行简单述评。     

Grignard试剂偶联法合成辅酶Q类化合物

以Grignard试剂偶联反应为构建C—C键的关键反应,由2,3,4,5-四甲氧基甲苯(1)出发,经过溴化、Grignard试剂制备、偶联、氧化等4步反应,成功地合成了辅酶Q2(6a)、Q4(6b)以及Q9(6c),反应总收率分别为66.1%、62.1%和65.1%,为辅酶Q类化合物的工业化合成提供了实验依据。     

Barton-Zard反应合成2-乙氧羰基-4,5,6,7-四氢异吲哚方法的改进

在碳酸钾作用下,1-硝基环己烯与异氰基乙酸乙酯在乙醇中发生Barton-Zard反应,得到2-乙氧羰基-4,5,6,7-四氢异吲哚。该方法使用碳酸钾代替有机碱DBU和易水解的叔丁醇钾,用乙醇代替四氢呋喃,溶剂毒性低,操作简便,产率更高。     

CrHZSM-5 Zeolites – Highly Efficient Catalysts for Catalytic Cracking of Isobutane to Produce Light Olefins

The CrHZSM-5 catalysts with trace amount of Cr were firstly used for catalytic cracking of isobutane, and the effect of Cr-loading on the catalytic performances of CrHZSM-5 catalysts for the cracking of isobutane was also studied. The results suggested that when the loading of Cr in the CrHZSM-5 catalysts was less than 0.038 mmol/g Cr, especially at Cr loading of 0.004 mmol/g, both the reactivity of isobutane cracking and the selectivity to light olefins of CrHZSM-5 samples were greatly enhanced compared with the unpromoted HZSM-5, and very high yields of olefins(C₂+C₃) and ethylene were obtained. For instance, the yield of olefins(C₂+C₃) and ethylene reached 56.1% and 30.8%, respectively, at 625 °C when 0.004 mmol/g Cr was loaded on HZSM-5 sample.     

Li-intercalation behaviour of vanadium oxide thin film prepared by thermal oxidation of vanadium metal

In order to produce thin films of crystalline V₂O₅, vanadium metal was thermally oxidised at 500 °C under oxygen pressures between 250 and 1000 mbar for 1-5 min. The oxide films were characterised by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). The lithium intercalation performance of the oxide films was investigated by cyclic voltammetry (CV), chronopotentiometry and electrochemical impedance spectroscopy (EIS). It was shown that the composition, the crystallinity and the related lithium intercalation properties of the thin oxide films were critically dependent on the oxidation conditions. The formation of crystalline V₂O₅ films was stimulated by higher oxygen pressure and longer oxidation time. Exposure for 5 min at 750 mbar O₂ at 500 °C resulted in a surface oxide film composed of V₂O_5, and consisting of crystallites up to 200 nm in lateral size. The thickness of the layer was about 100 nm. This V₂O₅ oxide film was found to have good cycling performance in a potential window between 3.8 and 2.8 V, with a stable capacity of 117 ± 10 mAh/g at an applied current density of 3.4 μA/cm². The diffusion coefficients corresponding to the two plateaus at 3.4 and 3.2 V were determined from the impedance measurements to (5.2 and 3.0) × 10⁻¹³ cm² s⁻¹, respectively. Beneath the V₂O₅ layer, lower oxides (mainly VO₂) were found close to the metal. At lower oxygen pressure and shorter exposure times, the oxide films were less crystalline and the amount of V⁴⁺ increased in the surface oxide film, as revealed by XPS. At intermediate oxygen pressures and exposure times a mixture of crystalline V₂O₅ and V₆O₁₃ was found in the oxide film.