Continuous‐Flow Microwave Synthesis of Metal–Organic Frameworks: A Highly Efficient Method for Large‐Scale Production

Metal–organic frameworks are having a tremendous impact on novel strategic applications, with prospective employment in industrially relevant processes. The development of such processes is strictly dependent on the ability to generate materials with high yield efficiency and production rate. We report a versatile and highly efficient method for synthesis of metal–organic frameworks in large quantities using continuous flow processing under microwave irradiation. Benchmark materials such as UiO‐66, MIL‐53(Al), and HKUST‐1 were obtained with remarkable mass, space–time yields, and often using stoichiometric amounts of reactants. In the case of UiO‐66 and MIL‐53(Al), we attained unprecedented space–time yields far greater than those reported previously. All of the syntheses were successfully extended to multi‐gram high quality products in a matter of minutes, proving the effectiveness of continuous flow microwave technology for the large scale production of metal–organic frameworks.     

Partially Hydrogenated Graphene Materials Exhibit High Electrocatalytic Activities Related to Unintentional Doping with Metallic Impurities

Partially hydrogenated graphene materials, synthesized by the chemical reduction/hydrogenation of two different graphene oxides using zinc powder in acidic environment or aluminum powder in alkaline environment, exhibit high electrocatalytic activities, as well as electrochemical sensing properties. The starting graphene oxides and the resultant hydrogenated graphenes were characterized in detail. Their electrocatalytic activity was examined in the oxygen reduction reaction, whereas sensing properties towards explosives were tested by using picric acid as a redox probe. Findings indicate that the high electrocatalytic performance originates not only from the hydrogenation of graphene, but also from unintentional contamination of graphene with manganese and other metals during synthesis. A careful evaluation of the obtained data and a detailed chemical analysis are necessary to identify the origin of this anomalous electrocatalytic activity.     

Ruthenium(II) complexes derived from 2‐phenylthiazoline‐4‐carboxylic acid: structure and catalytic activity for transfer hydrogenation reaction

Piano‐stool ([(p‐cymene)Ru(thz)Cl], 2 ) and six‐coordinated ([Ru(thz)₂(PPh₃)₂], 3 ) ruthenium complexes derived from 2‐phenylthiazoline‐4‐carboxylic acid (Hthz, 1 ) were synthesized for the first time, and fully characterized using conventional methods. Also, the molecular structure of complex 3 was determined using X‐ray analysis. These complexes were evaluated as catalysts for transfer hydrogenation of carbonyl compounds in the presence of isopropyl alcohol and KO^tBu. Complex 2 was found to be more active than 3 in transfer hydrogenation. Copyright © 2016 John Wiley & Sons, Ltd.     

Transfer hydrogenation of aryl ketones with homogeneous ruthenium catalysts containing diazafluorene ligands

Novel cationic ruthenium(II) complexes bearing a 4,5‐diazafluorene unit and p‐cymene as ligands have been synthesised. The complexes were characterised based on elemental analysis and Fourier transform infrared and nuclear magnetic resonance spectroscopies. The synthesised Ru(II) complexes were employed as pre‐catalysts for the transfer hydrogenation of aromatic ketones using 2‐propanol as both hydrogen source and solvent in the presence of NaOH. All complexes showed high catalytic activity as catalysts in the reduction of substituted acetophenones to corresponding secondary alcohols. The products of catalysis were obtained with conversion rates of between 80 and 99%. Among the seven new complexes investigated, the most efficient catalyst showed turnover frequencies in the range 255–291 h^?1 corresponding to 85 to 97% conversion, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

共沉淀浸渍法制备由合成气直接合成二甲醚的Cu-Mn催化剂

采用共沉淀浸渍法,制备了直接合成二甲醚的Cu-Mn-Zn催化剂,通过对组成成分及其配比的研究,发现Cu含量一定的条件下,n(Zn)/n(Mn)摩尔比对催化剂性能有较大的影响,当n(Zn)/n(Mn)=1/3～1/2时,催化剂对CO的转化率和对二甲醚的选择性达到最佳,分别为53.6%和63.5%；如锰添加比例过大,对催化剂催化合成二甲醚有微弱抑制；添加锌比例过大,会大大降低CO的转化率。载体Y分子筛的含量对催化剂性能也有影响,用量过大将降低催化剂的活性和对二甲醚的选择性,当其含量为33%时,催化剂上CO转化率和选择性可分别达到66%和68%,且催化剂活性随分子筛含量减少不再有明显的变化。     

微波等离子体下一氧化碳氢化制乙炔反应中产物的选择性研究(英文)

采用微波等离子体技术研究了一氧化碳氢化制乙炔反应的产物选择性。对影响乙炔选择性的几个因素,如微波输入功率、反应物的比例和体系压力进行了研究。乙炔的选择性随着微波输入功率的增加,反应物比例和体系压力的降低而增大。在最佳条件下,乙炔的选择性可达到９５．８７％,甲烷选择性的变化规律和乙炔相反,乙烯和乙烷的选择性很低。等离子体中的电子温度（或能量）和密度采用了静电悬浮双探针诊断,电子密度和能量受微波输入功率和体系压力的影响。在反应中,电子能量决定化学反应是否进行,电子密度决定产物的组成。根据自由基反应理论解释了乙炔选择性在Ｈ２＋ＣＯ等离子体化学反应中随影响因素的变化规律。     

有限自由度系统的定域Lie对称性和守恒量

研究有限自由度系统定域Lie对称性的正问题和逆问题。给出了定域Lie对称性的定义、确定方程、结构方程和守恒量。进一步从定域Lie对称性导出在有限连续群无限小变换下的Lie对称性。最后给出一个例子去说明这些结果。     

亚微秒脉冲表面介质阻挡放电等离子体诱导连续漩涡的研究

使用粒子激光图像测速技术对亚微秒脉冲激励表面介质阻挡放电激励器连续产生诱导漩涡进行了实验研究, 给出了包含脉冲重复频率和漩涡频率的双频率激励模式的具体形式. 实验过程中出现了原发型与继发型两类示踪粒子空白区, 前者由放电释热的微爆炸作用造成, 使得诱导流动远离壁面, 能够减小壁面摩擦阻力的作用; 以暴露电极左侧继发型空白区被完全吹除作为重复启动激励的临界点. 为提高控制效果应采用尽可能高的脉冲重复频率, 漩涡时间内脉冲数量应大于10, 最大诱导速度随脉冲数量增大而增大, 但动量传递效率降低. 使用亚微秒脉冲激励具备释热、体积力两种作用机理. 关键词： 双频率亚微秒脉冲 表面介质阻挡放电 连续漩涡