酸-碱交替沉淀法制备铜基甲醇合成催化剂

 采用酸-碱交替沉淀法(AP法)制备了一种新型的低压甲醇合成催化剂. 研究了母液pH值和交替次数对催化剂性能的影响. 结果表明, pH值交替范围为5.0～9.5, 交替次数为3时制备的催化剂活性最好. 与其它制备方法相比, AP法制备的催化剂具有最高的活性和耐热性,耐热后活性保留率达88%, 比其它催化剂高8%～20%, 而且耐热后活性甚至高于其它催化剂的初活性. X射线衍射(XRD)、热重分析、低温N2吸附和扫描电子显微镜等结果表明, AP法制备的催化剂的XRD谱中铜和锌的特征峰最为宽化、弥散, CuO与ZnO 峰交织在一起,峰强度最弱; 同时催化剂的粒度较小,粒径尺寸分布较均匀,结晶度相对较低; 而且催化剂的还原温度最低,铜锌组分间的协同作用最强. 这表明AP法制备的催化剂具有高活性、高耐热性和易还原的主要原因是该制备方法使催化剂中的铜锌组分形成了无定形状态的铜锌固溶体,提高了活性组分的分散度和比表面积.     

二茂铁手性膦配体研究的一些新进展

综述了具有独特结构的二茂铁手性膦配体的合成及应用. 这类化合物在催化不对称合成反应中表现出了很高的活性.     

锂离子电池正极材料线团状α-MnO2的合成及电化学性能

以MnSO₄, (NH₄)₂S₂O₈为反应物,Ag⁺作为催化剂的溶液相方法合成了线团状的α-MnO₂。采用XRD、SEM和TEM等手段对合成产物进行了表征。发现反应温度和反应时间对产物的结晶度和形貌有很大的影响。通过恒电流充电/放电测试和循环伏安法(CV)对最终产物的电化学性能进行了表征。结果表明,由于其独特的形态,25 ℃下反应2 d的产物作为锂离子电池正极材料,表现出良好的循环稳定性(100次循环后放电比容量为124 mAh·g^-1)。线团状α-MnO₂在锂离子电池应用中可能是一个潜在的正极材料。     

溶剂热一锅法合成Ag-TiO2微球及其对过氧化氢的电化学检测

采用溶剂热法,通过调控钛酸四丁酯在醇水浴中的醇解作用和维生素C的烯醇还原性制备了细分散的纳米银修饰TiO_2微球。一锅法的制备过程绿色、程序简单,可获得分布均匀的微球,直径约250 nm,微球表面细分散的银晶格具有(111)晶面特征。构建的Ag-TiO_2微球电极对H_2O_2具有良好的电催化活性,展现出良好的电化学检测性能,当H_2O_2的线性范围为0.1～102μmol·L~(-1)时,传感电极的灵敏度为3.13×10~(-3)μA·L·μmol~(-1)·cm~(-2),最低检测限可达0.04μmol·L~(-1)。所得传感器具有良好的长期稳定性、重现性和重复性,一个月后,性能保持率仍可维持在82.1%。     

大环芳烃菲咯啉的设计、合成及其铜光敏剂光解水制氢性能

设计、合成了一类4,7位为大环芳烃的菲咯啉二齿氮配体,可与铜.和Xantphos原位配位,获得一系列新型氮磷杂配铜光敏剂CuPS 1～CuPS 6,在均相光解水制氢体系中研究其光敏活性及构效关系。实验结果表明,在菲咯啉4,7位引入芳基有利于提高其光敏活性,1-萘基取代的CuPS 3有最好的制氢活性,光解水制氢转化数(TON)达957。通过理论计算对比分析,1-萘基取代基与菲咯啉母核具有较大的二面角,对铜配合物的激发态有较好的保护作用,因此CuPS 3表现出较高的荧光量子产率(0.036)和较长的激发态寿命(1.36μs)。     

高热稳定性Cu-Mn-O催化燃烧催化剂的制备

采用共沉淀法制备Cu-Mn-O前驱体, 以水洗和醇洗的方式去除杂质, 在空气气氛下干燥焙烧获得催化剂. 用BET、 XRD、 SEM对此催化剂的比表面积、晶相结构以及颗粒形貌进行了表征, 并以甲苯催化燃烧为探针反应考察了催化剂的性能. 结果表明, 在500 ℃焙烧, Cu-Mn-O催化剂的比表面积可以达到67.9 m2/g, 颗粒尺寸在100 nm左右并高度分散. 与水洗样品相比, 醇洗样品的活性相CuMn2O4热稳定性得到较大提高, 经700 ℃焙烧的Cu-Mn-O上甲苯完全燃烧温度降低了60 ℃;800 ℃焙烧后, 甲苯完全燃烧温度降低了约50 ℃.     

多相硅氢加成催化剂的制备及应用

硅氢加成反应是有机硅化学领域最为重要的反应之一。自该反应于1947年被发现以来,大量的文献对其进行了报道。本文综述了近十年来应用于硅氢加成反应的各类负载型催化剂的研究进展,介绍了活性炭、二氧化硅、分子筛等负载过渡金属催化剂,重点介绍了有机-无机杂化载体负载Pt、Rh、Au等多相催化剂的制备方法及其在硅氢加成反应中的应用,并分析了其催化作用机理;总结了功能高分子化合物负载过渡金属在硅氢加成反应中的研究,和新型含不同官能基团的离子液体络合金属催化剂的制备方法及其对不饱和烃与含氢硅烷的硅氢加成反应的催化性能,总结和讨论了催化反应机理的研究,并对多相硅氢加成催化剂的发展方向进行了分析和展望。     

具有聚集诱导发光特性的新型铂(Ⅱ)金属配合物及其光激发的自敏化氧化反应

The excited states of transition metal complexes with a wide range of photochemical and photophysical properties have attracted considerable attention recently. However, the luminescence property is affected by concentration quenching in practical applications. Aggregation-induced emission (AIE) is an effective strategy to solve this problem. In this work, a new imidazole-based N^C^N Pt(Ⅱ) metal complex, PtP2IM, with the AIE property was synthesized and characterized according to its single crystal structure. Under visible light, we found that the metal complex undergoes a photo-oxidation reaction with the generation of a new red-emitting, imidazole/benzoylimino-based N^C^N' Pt(Ⅱ) metal complex, PtPIMO, which was also confirmed by the crystal structure. Additional studies on the reaction process and conditions of this photo-oxidation reaction were conducted using different methods, such as NMR, UV-Vis spectroscopy, and so on. The experimental results showed that the change from PtP2IM to PtPIMO gradually occurred, and the new photochemical reaction was finally concluded as the C＝C double bond in either one of the two imidazole rings of the PtP2IM complex was attacked by oxygen to generate a new complex, PtPIMO, under photoirradiation in air. Electron paramagnetic resonance (EPR) measurements demonstrated the production of singlet oxygen, which is an excited state of oxygen with a high energy. Through the density functional theory (DFT) calculations, the electronic transition was determined to be a metal to ligand charge transfer (MLCT) in which more energy could transfer from the triplet excited state of PtP2IM to the ground-state oxygen to generate singlet oxygen (¹O₂) with a high intersystem crossing (ISC) efficiency due to the spin-orbit coupling of Pt heavy atoms. When large amounts of the singlet capture agent, triethylenediamine (TEDA) were added, the previously observed UV-Vis spectra change that corresponded to the photo oxidation reaction was not detected, which means that the photo-oxidation reaction observed in the case of PtP2IM was because of the oxidation by singlet oxygen. When oxygen was removed, excellent photostability and an obvious aggregation-induced emission (AIE) were observed for PtP2IM with the luminescent quantum efficiency of PtP2IM in solution and as a film at ~3% and ~20%, respectively. Based on the packing structure in the crystal, we observed that there were no strong intermolecular interactions, such as π-π or Pt-Pt interactions. Additionally, many intermolecular CH―π bonds between the two adjacent PtP2IM molecules were observed, which could effectively limit the rotation of the peripheral phenyl group linked to the imidazole ring. Thus, the AIE property of PtP2IM was attributed to the restricted intramolecular rotation (RIR) effect of the peripheral flexible phenyl group that was linked to the imidazole ring in the solid state in which the vibration of multiple peripheral benzene rings was effectively suppressed. This decreased the non-radiative transition rate and induced the high luminescent quantum efficiency. In the aggregation state, PtP2IM still demonstrated the photo-oxidation reaction by singlet oxygen. Thus, we report a new Pt(Ⅱ) metal complex, PtP2IM, with the AIE property that can undergo an uncommon photo-oxidation reaction in the photo-excitation state. This work aimed to elucidate the basic photochemical and photophysics of transition metal complexes with the AIE property.     

低负载量的双金属Au@Pt核壳催化剂催化氧化甲苯

采用液相氢气两步还原法制备了双金属Au@Pt核壳纳米粒子,通过直接吸附法将纳米粒子均匀地分散于载体上,制备出低负载量的双金属Au@Pt/Al₂O₃催化剂,并且评价了催化剂对甲苯的催化氧化性能。通过TEM、XRD、XPS、N₂吸附-脱附和H₂-TPR等对催化剂进行了表征。结果表明,与单金属Au和Pt催化剂相比,双金属Au@Pt核壳催化剂表现出更高的催化活性,具有很好的稳定性和选择性,在甲苯体积分数为1×10^-3,气体空速为18 L·g^-1·h^-1的条件下,Au₁@Pt₂/Al₂O₃核壳催化剂具有优异的催化氧化性能,其中甲苯实现98%的转化率的温度（T₉₈）为195℃。由XPS结果可知,在Au和Pt之间存在电子转移促进了Pt上活性氧物种的形成,催化剂的活性组分主要以Au⁰和Pt⁰的形式存在,并广泛分布在载体的表面上。Au@Pt纳米粒子与载体Al₂O₃之间的强相互作用也是提高甲苯催化氧化活性的重要因素。     

电化学氧化和臭氧化预处理酸性化工废水的效能研究

保持一定酸度条件下对比了电化学氧化和臭氧氧化预处理酸性化工废水的效能（废水原pH 0.85）. 结果表明,在废水中添加2 g·L^-1 NaCl电化学氧化预处理效果较佳,30 mA·cm^-2条件下电解20 min后水样的CODCr（化学需氧量）去除率达43.4%,BOD₅/COD_Cr（生化需氧量与化学需氧量的比值）值从原来的0.034上升至0.14,可生化性明显提高. 单独臭氧化仅在pH 7.0才能取得一定的预处理效能. Ti(Ⅳ)/O₃/H₂O₂高级氧化体系在pH 2.85条件下亦有较好的预处理效果,16 min后水样COD_Cr去除率达22.9%,BOD₅/COD_Cr值则提高至0.072.