喷雾干燥-固相煅烧法制备球形钛酸狸负极材料的研究

通过喷雾干燥-固相煅烧法制备了球形钛酸钾.不同于传统喷雾干燥工艺采用固态钛源进行制备,本文采用的前驱体是钾盐,分散剂和钛酸四丁酯制备出的硝酸氧钛的混合溶液.由于制备方法中前驱体为原子级均匀分布,化学计量比可精确控制,制备出的材料颗粒细小,粒径、成分分布均匀,电化学性能优异.同时研究了不同钾钛摩尔比以及煅烧温度对球形钛酸钾的形貌和成分的影响,并研究了其作为钾离子电池电极材料的电化学性能.结果表明,钾钛摩尔比为0.816,煅烧温度为 800 ℃时钛酸钾的电化学性能最好,首圈容量 185.1 mAh/g,30 圈后容量为173.9 mAh/g,循环100圈后还有169.7 mAh/g的容量.     

CO在超临界水中的转化以及碱性钾盐的影响

构建了CO高压溶解的进气系统，在连续式反应系统中对超临界水条件下CO的转化规律进行了研究；针对生物质超临界水气化中钾盐的多样性，选择KHCO₃、K₂CO₃和KOH等三种钾盐成分，研究了它们在不同工艺条件（450-600℃、23-29 MPa、停留时间3-6 s）下对超临界水中水煤气转化过程的影响。结果表明，在无催化条件下，提高反应温度、延长停留时间均提高了CO的转化率，而压力对其影响在低压下（23-25 MPa）比较大，高压下（25-29 MPa）比较小，水煤气转化的反应动力学方程为k=10^3.75×exp（-0.66×10⁵/RT）（s^-1）。碱性钾盐均能显著提高CO转化率，其催化促进程度从大到小依次为：KHCO₃>K₂CO₃>KOH。添加碱性钾盐时，提高反应温度、延长停留时间均提高CO转化率，而压力的影响比较复杂。碱性盐对水煤气转化反应的催化是通过草酸盐（HC₂O₄^-）和甲酸盐（HCOO^-）作为中间产物进行的。     

1, 1'-双(二苯基膦基)二茂铁介导的芳烃碳氢键芳基化反应制备联芳基骨架

The broad existence of the biaryl linkage in bioactive organic molecules and functional materials makes it an attractive synthesis target via construction of aryl-aryl carbon bonds. Transition metal catalyzed cross-coupling reactions of two pre-functionalized aryl partners, e.g., Suzuki-Miyaura cross-coupling and Negishi cross-coupling reactions, are the main methods typically used for the construction of biaryl linkages. Since the end of the last century, transition metal catalyzed direct C―H arylation of unactivated arenes has emerged as a practical alternative to the well-established cross-coupling strategies. However, the use of transition metal catalysts and/or organometallic reagents would lead to problems, such as the disposal of waste from large-scale syntheses and the removal of heavy metal contaminants from pharmaceutical intermediates. In this regard, the base-promoted homolytic aromatic substitution (BHAS) reaction of aryl halides with unactivated arenes offers a simpler strategy for the synthesis of biaryl scaffolds, and avoids the use of transition metals. Although the BHAS reaction can proceed to a small extent without any additives, particularly at elevated temperatures, the addition of organic promoters would significantly accelerate the reaction rate and improve the overall efficiency of the process. Over the past ten years, a wide variety of N- and O-based organic promoters have been developed to promote the BHAS reaction in the presence of the tert-butoxide base. The mechanism of the BHAS reaction has been studied extensively, and is accepted as occurring via a radical chain process involving an aryl radical. However, the role and mode of initiation of most organic promoters studied remain controversial. The development of more and varied organic promoters will surely promote the mechanistic understanding and further development of the BHAS reaction. Herein, we report that 1, 1'-bis(diphenylphosphino)ferrocene (dppf, or DPPF) can act as a P-based promoter to facilitate the direct arylation of unactivated arenes with aryl iodides using potassium tert-butoxide as the base and electron donor. A broad range of aryl iodides and arenes reacted smoothly under the optimized reaction conditions, giving arylated products in good yields and with high regio-selectivity. Intramolecular C―H arylation also worked well following a sequence of single electron transfer (SET)/initiation, 5-exo-trig aryl radical addition, ring expansion, deprotonation, and re-aromatization/propagation. A mechanistic study indicated that the diphenylphosphino group of dppf played a vital role in the initiation step by enhancing the SET-inhibiting ability of the tert-butoxide anion. A primary kinetic isotope effect was observed in the parallel reactions between 4-methoxy-iodobenzene with benzene and deuterated benzene, implying that the deprotonation of the cyclohexadienyl radical intermediate by tert-butoxide was the rate-determining step in the radical chain pathway.     

添加叔丁醇钾对Mg(NH2)2-2LiH体系储氢性能的影响

叔丁醇钾(C_4H_9OK)的添加显著改善了Mg(NH_2)_2-2LiH体系的储氢性能。添加0.08 mol C_4H_9OK的Mg(NH_2)_2-2LiH-0.08C_4H_9OK样品表现出最佳储氢性能。该样品的起始放氢温度仅为70℃,较Mg(NH_2)_2-2LiH原始样品降低了60℃;130℃完全放氢后,该样品可在50℃开始吸氢,较原始样品降低了50℃。Mg(NH_2)_2-2LiH-0.08C_4H_9OK样品可在150℃的等温条件下50min内迅速放出质量分数3.82%的氢气,完全放氢后可在120℃的等温条件下50 min内快速吸收质量分数4.11%的氢气,表现出良好的吸放氢动力学性能。C_4H_9OK的添加降低了样品放氢反应的表观活化能和反应焓变,改善了放氢反应的动力学和热力学性能,从而降低了放氢反应温度。进一步的放氢反应机理研究发现,在180℃之前,C_4H_9OK对Mg(NH_2)_2-2LiH体系的放氢起催化改性作用;温度继续升高后,C_4H_9OK将会分解并参与放氢反应最终生成Li_3K(NH_2)_4。     

溶胶-凝胶法制备NixCo1-xCoAlO4尖晶石型复合氧化物及其催化分解N2O性能

用溶胶凝胶法制备了一组Ni_xCo_1-xCoAlO₄尖晶石型复合氧化物,并采用表面润湿浸渍K₂CO₃溶液进行了K掺杂改性,用于有氧气氛下的N₂O催化分解反应.采用N₂物理吸附、X-射线衍射(XRD)、扫描电镜(SEM)、H₂-程序升温还原(H₂-TPR)等技术对催化剂进行了表征,考察了催化剂组成、母液pH值、K负载量等制备参数对其催化活性的影响.结果表明,母液pH值为3、K/(Ni+Co)物质的量比为0.1的K/Ni_0.15Co_0.85CoAlO₄催化剂具有较高的N₂O分解活性,450 ℃ N₂O可完全分解.助剂K的加入弱化了催化剂表面金属氧键,提高了催化剂的还原性、催化活性和抗水性.     

离子液体添加剂对硬脂酸钾固体润滑薄膜摩擦磨损性能的影响

采用浸渍-提拉方法在单晶硅片上制备硬脂酸钾以及添加离子液体的硬脂酸钾复合薄膜,采用DF-PM型静-动摩擦磨损试验机考察薄膜在低速滑动条件下的摩擦磨损性能,采用扫描电子显微镜和X射线能量散射谱仪观察分析薄膜及其偶件表面的磨损形貌及典型元素面分布.结果表明:在相对低速滑动条件下,在羟基化硅基底上制备的复合薄膜的摩擦磨损性能优于硬脂酸钾薄膜;在载荷为1.0 N条件下,含离子液体质量分数40.0%的复合薄膜的耐磨寿命超过5 000次,而硬脂酸钾薄膜仅为100次左右;随着复合薄膜中离子液体含量增加,复合薄膜更容易在偶件钢球表面形成有效转移薄膜,使复合薄膜摩擦磨损性能得以提高.     

硼酸钾做润滑油添加剂的抗磨性能之研究

作者利用Shell-Seta四球试验机研究了白油中所含硼酸钾的抗磨特性,以及分散刘中性烷基苯磺酸钙对硼酸钾抗磨性能的影响,并且利用X-射线光电子能谱仪(XPS)和俄歇电子能谱仪(AES)考察了摩擦表面的元素组成及硼元素的价态。结果表明,含硼酸钾的白油能够在摩擦表面形成含硼酸钾的表面膜而具有较好的抗磨性,硼在摩擦表面膜中以硼酸钾的形式存在,分散剂烷基苯磺酸钙会影响硼酸钾沉积腆的形成及其与金属表面的结合强度而降低抗磨性能。     

磷酸钾缓冲溶液与模型细胞膜相互作用的和频光谱

利用和频光谱技术详细研究了磷酸钾缓冲溶液与带负电荷的生物仿生膜(d₅₄-DMPG磷脂双层膜)相互作用的实时过程．通过监控CD₂、CD₃、磷脂分子头部的磷酸根以及羰基官能团的光谱信号随加入磷酸钾缓冲溶液的实时变化,获得了磷脂双层膜分子结构的动力学变化．结果表明K⁺能够结合到细胞膜上,并且很快地引起了CD₂、CD₃、磷脂头部磷酸根以及羰基官能团信号的变化．根据各官能团的和频信号响应,磷酸钾缓冲溶液很可能是通过在双层膜中形成环形气孔来与磷脂双层膜发生作用．该结果可以很好地解释磷酸钾缓冲溶液环境下的离子协助蛋白质的跨膜过程．     

聚酰亚胺/钽铌酸钾纳米颗粒复合材料结构与机械性能分子动力学模拟

利用多尺度建模方法构建了聚酰亚胺/钽铌酸钾纳米颗粒复合物模型, 通过分子动力学模拟研究了不同尺寸钽铌酸钾纳米颗粒(5.5, 8.0, 9.4, 10.5, 11.5 Å)对复合材料的结构、弹性模量和相互作用能的影响规律, 并通过计算纳米颗粒表面原子键能和单位表面积原子数目探究了复合物机械性能提高的内部机理. 聚酰亚胺和聚酰亚胺/钽铌酸钾复合材料的杨氏模量分别为2.91和3.17 GPa, 泊松比分别为0.37和0.35, 钽铌酸钾纳米颗粒的引入可以显著改善聚酰亚胺的机械性能. 纳米颗粒表面原子的键能为8.62-54.37 kJ·mol^-1, 表明颗粒与基体主要通过范德华力作用结合且有氢键存在. 计算结果表明, 相同掺杂比例下, 纳米颗粒尺寸越小, 纳米颗粒表面原子数目越大, 颗粒与基体作用更强, 杨氏模量的提高幅度越大, 尺寸效应越显著. 因此, 掺杂小尺寸纳米颗粒是提高聚酰亚胺机械性能的有效途径.