平台石墨炉原子吸收法测定高温镍基合金中铋

本文用１ｍｇ／ｍＬ镍和０．２ｍｇ／ｍＬ钯作混合基体改进剂，提高了测定铋的灰化温度和抗干扰能力，且灵敏度几乎不变。可不经分离样品基体，直接用平台石墨炉原子吸收法测定高温镍基合金中铋。方法特征量为１８ｐｇ，检出限为０．０８１μｇ／ｇ。对含０．３－０．７μｇ／ｇ铋的镍基样品测定，相对标准偏差为３．０％－５．９％，回收率在８５％－１１９％之间。     

浆态床F-T合成反应中反应参数对e/Cu/K/SiO2催化剂性能的影响

 用喷雾干燥法制备了微球状Fe/Cu/K/SiO2催化剂,并在不同的反应条件下对其在浆态床F-T合成反应中的催化性能进行了评价. 结果表明,反应温度和原料气H2/CO比的调变对催化剂运行稳定性的影响较大,反应初始阶段加入的液体石蜡介质对催化剂运行稳定性的影响不大. 原料气空速的增加可有效地提高反应的总烃时空产率,但同时CO转化率会明显降低,且重质烃选择性下降; 低H2/CO比的原料气有利于在保持合适的转化率的同时提高重质烃的选择性,并可明显提高总烃的时空产率; 提高系统压力可增大催化剂的催化活性,改善重质烃的选择性; 而提高反应温度尽管可明显提高催化剂活性,但同时也会促进WGS反应的发生,降低重质烃的选择性. 因此,浆态床F-T合成反应中操作参数的适当调变可使催化剂活性、产物烃分布和烃产率得到有效优化,最大限度地获得目的产物.     

四丁基二锡氧烷催化合成碳酸二酯类化合物的新方法

 以四丁基二锡氧烷为催化剂，通过尿素的醇解反应，合成了四种\r\n高沸点碳酸二酯化合物．研究结果表明，尿素的第一步醇解反应较易进\r\n行，产物收率大于60％；第二步从氨基甲酸酯醇解变为碳酸二酯的反应\r\n较难进行．尿素醇解反应与所用的醇有密切的关系，其中尿素与苯甲醇\r\n醇解为碳酸二酯的反应最易进行，正己醇次之，而正辛醇反应最难进行\r\n．提高反应温度到195℃，以官能团为NCS的四丁基二锡氧烷代替官能团\r\n为Cl的四丁基二锡氧烷为催化剂时，适当提高醇的配比，尿素与正辛醇\r\n醇解为碳酸二酯的产物收率有较大的提高．提出了尿素醇解反应的可能\r\n机理．     

悬浮液进样石墨炉原子吸收光谱测定贻贝样品中铅、镉和铜

本文采用直接进样原子吸收光谱法测定贻贝标准物质中的Pb、Cd和Cu。首先将样品配制成悬浮液,然后直接注入石墨原子化器进行分析。由于不经样品消解,分离和富集等操作,节省了大量时间,文章讨论了基体改进效应和酸度影响。当Pb、Cd和Cu含量分别为2.02,4.98和7.46μg/g时,相对标准偏差分别为8.2％、4.2％和7.5％;加入回收率处于93～115％之间。最后与酸溶样法和标准值进行了对照,得到了一致结果。     

Sustainable and High-Rate Electrosynthesis of Nitrogen Fertilizer

The conventional industrial production of nitrogen-containing fertilizers, such as urea and ammonia, relies heavily on energy-intensive processes, accounting for approximately 3 % of global annual CO₂ emissions. Herein, we report a sustainable electrocatalytic approach that realizes direct and selective synthesis of urea and ammonia from co-reduction of CO₂ and nitrates under ambient conditions. With the assistance of a copper (Cu)-based salphen organic catalyst, outstanding urea (3.64 mg h⁻¹ mg_cat⁻¹) and ammonia (9.73 mg h⁻¹ mg_cat⁻¹) yield rates are achieved, in addition to a remarkable Faradaic efficiency of 57.9±3 % for the former. This work proposes an appealing sustainable route to converting greenhouse gas and waste nitrates by renewable energies into value-added fertilizers.     

铁基催化剂成型方式对浆态床费-托合成反应性能的影响

采用连续共沉淀方法制备了无定形Fe-Cu-K-SiO2催化剂,利用连续共沉淀与喷雾干燥成型技术相结合的方法制备了不同粒径的微球形Fe-Cu-K-SiO2催化剂.在接近反应工况的条件下对催化剂进行了浆态床费-托合成(FTS)反应性能评价,并对催化剂进行了物性表征.表征结果表明,无定形催化剂没有规整的外形和均一的粒径分布,微球形催化剂的表面光滑,球形度好,颗粒分布均匀.浆态床FTS反应评价结果表明,尽管无定形催化剂的初活性及最高活性较高,但蜡产物与催化剂的在线分离困难;随着成型时平均粒径的增大,微球形催化剂的活性降低,但失活速率减慢,烃产物选择性向轻组分方向偏移,容易实现蜡产物与催化剂的在线分离.     

β-三芳基锗-α(β)-取代丙酸同1-乙氧基锡杂恶唑烷的 反应

利用β-三芳基锗-α(β)-取代丙酸同1-乙氧基锡杂恶唑烷的1-位取代反应,合成了15个1-[(β-三芳基锡-α(β)-丙酰氧基]-2,8,9-三氧杂-5-氮杂-1-锡杂三环[3,3,3,0^1.5]十一烷,并研究该反应规律,利用IR,NMR和MS表征了该类化合物的结构和质谱裂解机制,生物活性测定表明,它们只对某些细菌如溶血链球菌和金黄葡萄糖球菌有较好的抑制作用。     

Synthesis and characterization of ferrocenylalkoxygermatranes and crystal structures of FcCH2OGe (OCH2CH2)3N and FcCH(CH3)OGe(OCH2CH2)3N1

Germatranes bearing a ferrocenylalkoxyl moiety have been obtained by the reaction of HOGe(OCH₂CH₂)₃N with various ferrocenyl alcohols. A convenient new synthesis method of FcCH₂OGe(OCH₂CH₂)₃N was reported. FcCH₂OGe(OCH₂CH₂)₃N was prepared in 93% yield when FcCH₂OH reacted with HOGe(OCH₂CH₂)₃N in chloroform at room temperature in the presence of molecular sieves (3 Å) as a dehydrating agent. All compounds were characterized by elemental analysis, ¹H NMR and IR spectroscopy. The molecular structures of FcCH₂OGe(OCH₂CH₂)₃N and FcCH(CH₃)OGe(OCH₂CH₂)₃N have been determined by X‐ray diffraction. The antitumor activities of FcCH₂OGe(OCH₂CH₂)₃N and p‐FcC₆H₄CH₂OGe(OCH₂CH₂)₃N were determined. Copyright © 2005 John Wiley & Sons, Ltd.     

三种席夫碱-Ni(Ⅱ)配合物的电子结构和吸收光谱的理论计算

采用B3LYP/6-31+G(d)-LANL2DZ方法优化了三种Ni(Ⅱ)的席夫碱配合物基态的几何构型,并在相同水平下进行了频率分析以确认稳定点的性质;利用含时密度泛函理论和极化连续介质模型(PCM),按TDB3LYP/6-31+G(d)-LANL2DZ水平计算了目标配合物在N,N-二甲基甲酰胺溶剂中的电子结构和吸收光谱.计算结果表明,配体中间位甲氧基的存在使配合物A具有较大的HOMO-LUMO能级差;且三种Ni(Ⅱ)配合物的S0→S1态的跃迁能按照A→B→C的顺序依次降低.     

Supercapacitive behaviors of the nitrogen-enriched activated mesocarbon microbead in aqueous electrolytes

The activated nitrogen-enriched novel carbons (a-NENCs) have been prepared by direct carbonization of polyaniline/activated mesocarbon microbead composites and further activated by 16 M?HNO₃. The electrochemical performances and supercapacitive behaviors of the a-NENCs in 6 M KOH, 1 M?H₂SO₄, and 0.5 M?K₂SO₄ solutions are evaluated by cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance spectroscopy, cyclic life, leakage current, and self-discharge measurements. The results demonstrate that the supercapacitors perform definitely supercapacitive behaviors; especially in 6 M KOH electrolyte, the supercapacitor represents much better electrochemical performance with more excellent reversibility, shorter relaxation time of 1.11 s, and nearly ideal polarizability. The maximum specific capacitance of the supercapacitors using a-NENCs as active electrode material is 85.1 F?g^?1 at a rate of 500 mA?g^?1 in 6 M?KOH. These outcomes indicate that the 6 M?KOH aqueous solution is a promising electrolyte for the supercapacitor with a-NENCs as electrode material.