Al18B4O33 aluminium borate: A new efficient support for palladium in the high temperature catalytic combustion of methane

Well crystallised aluminium borate Al₁₈B₄O₃₃ has been synthesised from alumina and boric acid with a BET area of 18 m²/g after calcination at 1100 °C. Afterwards, 2 wt.% Pd/Al₁₈B₄O₃₃ was prepared by conventional impregnation of Pd(NO₃)₂ aqueous solution and calcination in air at 500 °C. The catalytic activity of Pd/Al₁₈B₄O₃₃ in the complete oxidation of methane was measured between 300 and 900 °C and compared with that of Pd/Al₂O₃. Pd/Al₁₈B₄O₃₃ exhibited a much lower activity than Pd/Al₂O₃ when treated in hydrogen at 500 °C or aged in O₂/H₂O (90:10) at 800 °C prior to catalytic testing. Surprisingly, a catalytic reaction run up to 900 °C in the reaction mixture induced a steep increase of the catalytic activity of Pd/Al₁₈B₄O₃₃ which became as active as Pd/Al₂O₃. Moreover, the decrease of the catalytic activity observed around 750 °C for Pd/Al₂O₃ and attributed to PdO decomposition into metallic Pd was significantly shifted to higher temperatures (820 °C) in the case of Pd/Al₁₈B₄O₃₃. The existence of two distinct types of PdO species formed on Al₁₈B₄O₃₃ and being, respectively, responsible for the improvement of the activity at low and high temperature was proposed on the basis of diffuse reflectance spectroscopy and temperature-programmed desorption of O₂.     

阿奇霉素合成中硼酸酯水解的研究

对阿奇霉素合成中的两种硼酸酯,即阿奇霉素硼酸酯(AZMB)及其前体氮红霉素硼酸酯(AZAB)的水解进行了比较,AZAB的最佳水解条件为:pH=3.0、水解温度30℃、水解时间30 m in,转化率91.9%;AZMB的水解条件为:pH=2.0,温度30℃、反应时间90 m in,转化率为89.3%。实验表明,AZAB比AZMB更易水解。采用有机酸和无机酸的混合酸代替文献[6]中的无机酸调节水解的pH,可以抑制克拉定糖的酸性降解反应。通过改进后,以红霉素6,9-亚胺醚为原料,阿奇霉素二水化合物的总收率可以达到85%,经HPLC分析,质量分数为98.4%。     

硼酸铝晶须的应用与制备

无机材料在国民经济和国防建设中均占有重要地位，其中硼酸铝晶须作为一种新型的无机应用材料，由于其具有许多的特殊功能，而且相对廉价，近年来受到了人们的广泛关注。就硼酸铝晶须的组成、物化性能及主要用途作了简单介绍，并主要介绍了生产硼酸铝晶须两种主要方法——助熔法和水热法。指出与发达国家相比，中国在这方面的研究工作还有很大差距，今后如能大力开展制备和应用方面的研究，中国的许多工程材料的性能将得到极大的提高。     

膨胀型防火涂料炭化层形成过程的探讨

炭化层的形成过程和最终状态是决定钢结构膨胀型防火涂料耐火极限的主要因素 ,因此 ,如何形成轻质、均匀、致密和强度高的炭化层是这类涂料研究和生产的技术关键。膨胀型防火涂料的炭化层形成过程是在高温条件下剧烈的化学反应过程 ,因此 ,涂料配方中的各个组分在这种极端的反应条件下都有可能参与炭化层的形成 ,从而最终影响炭化层的形态。本文通过对有机物体系中常用的阻燃剂———硼酸锌在膨胀型防火涂料中的不同含量对涂料耐火极限和形成炭化层的形态影响 ,得出了硼酸锌的加入对膨胀型防火涂料的炭化层具有负面影响的结论。同时 ,通过涂料配方中不同树脂的试验 ,以及添加表面活性剂对炭化层的作用等 ,得出了各组分对炭化层形态的影响规律。并用泡沫塑料膨胀过程的理论分析对上述实验现象进行解释 ,对钢结构膨胀型防火涂料的配方研制具有实际指导意义。     

硼酸盐润滑油添加剂的发展动态

简要地阐述了硼酸盐润滑油加剂的发展现状和研究动态，对其多种制备方法进行了比较和总结，并重点对其性能和作用机理的研究进行了分析和归纳，特别强调指出，改善硼酸盐润滑油添加剂的储存稳定性和抗乳化性，研究其与含磷，硫，氮等活性元素添加剂的复配规律以及复配作用机理，是这一领域的主要趋势之一。     

有机模板硼酸盐[C2H8N][B5O6(OH)4]的合成及发光性能研究

以二甲胺和硼酸为原料,通过水热反应合成有机模板硼酸盐[C2H8N][B5O6 (OH)4],通过单晶X射线衍射对其晶体结构进行分析,该晶体属于单斜晶系,空间群为C2/c,晶胞参数为a=1.3381(75) nm,b=1.1468(56)nm,c=1.7137(92) nm,α=90.032(64)°,β=112.292(82)°,γ=89.988(85)°,V=2.433(2.000) nm3.粉末衍射(PXRD),红外(IR),热重(TGA)以及荧光(PL)等手段对其晶体进行分析表征.在不同温度下对该物质进行热处理,观察其IR和PXRD的变化判断其内部的结构是否能够保持稳定,并通过热重分析进行补充说明.荧光光谱结果表明在经过不同温度热处理后,该物质的发光特性发生明显的变化.实验证实[C2H8N] [B5O6(OH)4]一种可能用在白光LED上的荧光粉.     

Impact of tripropyl borate on life and impedance of lithium-ion cells

Tripropyl borate was investigated as a low cost anion receptor to improve the performance of lithium-ion cells. The impact of tripropyl borate was examined using lithium-ion cells comprising a negative electrode of mesocarbon microbeads, a positive electrode of Li_1.1[Mn_1/3Ni_1/3Co_1/3]_0.9O₂ and an LiPF₆-based electrolyte. It was found that the performance of the cells was improved by adding a proper amount of tripropyl borate (≤0.1 wt%) to the LiPF₆-based electrolyte. However, a small amount of gas was observed from cells with high contents of tripropyl borate when cycled at 55 °C, and as a result, the performance of the cells deteriorated.     

The Evaluation of Alkyl Borane Compounds and Imidazole Borate Complexes as Initiators for Acrylic Adhesives Bonding Low Energy Substrates

Novel amido-borate initiators based on imidazolide bridged borate complexes were developed for acrylic adhesives used to bond low surface energy substrates. The focus of this development was examining the shelf life of the acrylic adhesive system as a function of the molecular architecture of the organoboron curative. The two key molecular features which significantly affect stability are: 1) the chain length of the alkyl groups on the boron atom and 2) arrangement of the imidazolide bridged borate structure. The results show that superior shelf life stability can be attained over the conventional trialkyl borane- and tetraalkyl borate-type initiators when this new family of catalysts (imidazolide borate compounds) is incorporated into the adhesive formulation without any harmful effect on cure speed.     

Borate as a Phosphate Ester Mimic in Aldolase‐Catalyzed Reactions: Practical Synthesis of L‐Fructose and L‐Iminocyclitols

Dihydroxyacetone phosphate (DHAP)‐dependent aldolases have been widely used for the organic synthesis of unnatural sugars or derivatives. The practicality of using DHAP‐dependent aldolases is limited by their strict substrate specificity and the high cost and instability of DHAP. Here we report that the DHAP‐dependent aldolase L ‐rhamnulose 1‐phosphate aldolase (RhaD) accepts dihydroxyacetone (DHA) as a donor substrate in the presence of borate buffer, presumably by reversible in situ formation of DHA borate ester. The reaction appears to be irreversible, with the products thermodynamically trapped as borate complexes. We have applied this discovery to develop a practical one‐step synthesis of the non‐caloric sweetener L ‐fructose. L ‐Fructose was synthesized from racemic glyceraldehyde and DHA in the presence of RhaD and borate in 92 % yield on a gram scale. We also synthesized a series of L ‐iminocyclitols, which are potential glycosidase inhibitors, in only two steps.     

硼硅酸盐生物玻璃的制备及其体外生物活性和降解性

采用熔融法制备了NaO-CaO-SiO2-P2O5-B2O3玻璃,用质量损失分析、pH值测定和X射线衍射、电子显微镜以及电感耦合等离子体离子浓度分析法表征玻璃与稀K2HPO4溶液的类生物反应,研究了这类玻璃的生物活性和生物降解性.结果表明:当玻璃中B2O3/SiO2的摩尔比为3:1时,生物活性较好.随着B2O3与SiO2的摩尔比减小,玻璃的降解速度变慢,获得的羟基磷灰石结晶度较低.利用此特性可控制生物玻璃的降解速度,从而与骨细胞生长速度相匹配.因此,此类硼硅酸盐生物活性玻璃有望在硬组织工程支架材料中得到应用.