Extrapolation of Laboratory Reaction Kinetic Data for Relief Vent Design in the Case of a Heterogeneous Runaway Reaction

The relief area sizing of safety devices in the case of a postulated thermal runaway condition requires reaction kinetic data, usually measured in dedicated adiabatic calorimeters. In the course of the design, it is then assumed that the same reaction kinetic data prevail on the laboratory and production scale. This assumption seems to be valid in the case of homogeneous reaction systems. In contrast to this the results of experiments with a heterogeneous system have shown that the stirring intensity and the reactor size have a considerable influence on the reaction progress.This revised version was published online in November 2005 with corrections to the Cover Date.     

Risk Analysis in Transport and Storage of Monomers: An Accident Investigation

Summary: In this work the analysis of an accident in transport of dangerous goods is proposed. The objective of this study is to contribute to the determination of the causes that brought about the self-polymerization of commercial divinylbenzene (DVB 63%) contained in an iso-container, in order to prevent this accident to happen in the future. Time and conditions during transport and storage of monomers (in particular the storage temperature) are very important factors, that affect the self-polymerization aptitude of these substances. To stabilize this monomer, usually 4-tert-Butylcatechol (TBC) is added at a level of 900–1200 ppm by weight to act as an inhibitor to prevent the self-initiated autopolymerization of the material. In particular one hypothesis has been investigated: probably the quantity of oxygen in the tanker was insufficient to activate properly the inhibition mechanism of TBC. From this consideration the self-polymerization of DVB and the inhibition mechanism of TBC have been studied as a function of temperature and monomer exposure to air. Different calorimetric techniques have been applied, in particular Differential Scanning Calorimetry and Adiabatic Calorimetry, to investigate the causes of the accident.     

Time-variable Method for Studying Reaction Rates in a Calorimeter

A novel method for the determination of rate constants of reactions, the time-variable method, is proposed in this paper. The method needs only three time points (t), peak heights () and pre-peak areas (), obtained from the measured thermoanalytical curve. It does not require the thermokinetic reaction to be completed. It utilizes data-processing on a computer to give the rate constants. Four reaction systems, including a first-order reaction, second-order reactions (with equal concentrations and with unequal concentrations) and a third-order reaction, were studied with this method. The method was validated and its theoretical basis was verified by the experimental results.This revised version was published online in November 2005 with corrections to the Cover Date.     

反应类等键反应方法及类反应热动力学参数计算

本文提出了反应类等键反应方法,将通常用于热力学性质计算的等键反应方法推广用于类反应中反应势垒和反应焓变的计算. 对碳氢燃料低温燃烧反应机理中的一类重要反应类：?烷基自由基过氧化氢裂解生成烯烃和HO2自由基的反应势垒和反应焓变进行了计算. 通过对该类16个反应中的5个代表反应分别在不同计算水平HF、DFT、MP2、CCSD(T)的比较计算发现,采用等键反应方法可在较低从头算级别计算得到类反应较高精度的反应势垒,提高了计算的效率和精度. 本文采用反应类等键反应方法在B3LYP/6-311G(d,p)计算水平对该类16个反应进行了反应势垒和反应焓变的计算,并建立了反应势垒和反应能的线性自由能关系：delta V=71.02+0.41?delta E.     

KG-60-Piperazine as a New Heterogeneous Catalyst for Gewald Three-Component Reaction

Piperazine supported on amorphous silica (KG-60-piperazine) as a basic catalyst acts in the Gewald three-component reaction of some aldehydes and ketones with malononitrile as well as ethyl cyanoacetate. The catalyst shows general utility with a variety of starting carbonyl compounds. Moreover, the catalyst can be reused for four additional cycles without significant loss of the activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Corrosion Inhibition Efficiency of Polytriethanolamine Surfactants for Pipe-Lines Carbon Steel in 1M HCl

Fifteen organic compounds were prepared from triethanolamine and its derivative. The triethanolamine was polymerized by condensation to get P₄, P₆, and P₈ at different molecular weight. The P8 was ethoxylated at different ethylene oxide units (en) (40, 100, and 120) to obtain three compounds (E(en)P₈). Every degree of ethoxylate was esterified with 1, 4, and 8 moles of oleic acid to get on 9 ethoxylated polytriethanolamine esters (E(en)P₈Om). The effect of adding these organic compounds on the electrochemical behavior of carbon steel in 1 M HCl was investigated by using the weight loss technique. The reported results in this study show that the addition of these surfactants inhibits the corrosion of carbon steel. The inhibition efficiency (I%) for each inhibitor increases with increasing the concentration. The maximum inhibition efficiency (95%) was obtained by (E(40)P₈O₁) at 600 ppm. The inhibitive efficiency was discussed on the light of chemical structure of the used inhibitors.     

Variable Synthesis of Alcohols and Ketones Using the Grignard Method as a Form of MPVO Reaction

The unexpected occurrence of ketones 9 and 16 in addition to expected alcohols 5 and 15 in the synthesis of sesquiterpenes salsolenketone 1 and salsolene oxide 2 during Grignard reactions of the corresponding aldehydes with bromoalkenes under air‐ and water‐free conditions by the Meerwein–Ponndorf–Verley–Oppenauer reaction is reported. The product distribution could be influenced by the amounts of aldehyde used.     

Activation of Vegetable Oils by Reaction with Maleic Anhydride as a Renewable Source in Chemical Processes: New Experimental and Computational NMR Evidence

Vegetable oils are bio−based and sustainable starting materials that can be used to develop chemicals for industrial processes. In this study, the functionalization of three vegetable oils (grape, hemp, and linseed) with maleic anhydride was carried out either by conventional heating or microwave activation to obtain products that, after further reactions, can enhance the water dispersion of oils for industrial applications. To identify the most abundant derivatives formed, trans-3-octene, methyl oleate, and ethyl linoleate were reacted as reference systems. A detailed NMR study, supported by computational evidence, allowed for the identification of the species formed in the reaction of trans-3-octene with maleic anhydride. The signals in the ¹H NMR spectra of the alkenyl succinic anhydride (ASA) moieties bound to the organic chains were clearly identified. The reactions achieved by conventional heating were carried out for 5 h at 200 °C, resulting in similar or lower amounts of ASA units/g of oil with respect to the reactions performed by microwave activation, which, however, induced a higher viscosity of the samples.     

CO2 as Both a Selective Agent and Reaction Media in Palla-dium-Catalyzed Reductive Ullmann-Type Coupling Reaction

Carbon dioxide as both a selective agent and reaction media in the palladium-catalyzed Ullmann-type coupling has been described. The results showed that aryl chlorides could be easily activated in the presence of carbon dioxide and the chemoselectivity shifted toward the palladium-catalyzed Ullmann-type coupling reaction. In liquid carbon dioxide, homocoupling reactions of aryl halides, including less reactive aryl chlorides, were carried out smoothly in moderate to good yields using Pd/C, zinc, and H2O as the catalytic system at room temperature.     

多尺度炭材料担载铂作为稳定的电催化剂用于氧还原反应

炭载体的稳定性对于燃料电池电催化剂是至关重要的. 本文中采用酚醛树脂作为前驱体,二氧化硅为模板剂,制备了多介孔且石墨化程度高的炭载体（HGMC）. 相比于商品Vulcan XC-72,HGMC具有中等的比表面积和高的石墨化程度,因此在电位循环扫描过程中具有较高的化学稳定性,然而HGMC碳层堆叠的结构不利于传质. 为克服这一劣势,多壁碳纳米管（MWCNTs）作为隔离物加入至HGMC中以构建具有三维多尺度结构的载体（MSGC）. 与HGMC为载体担载Pt以及商品催化剂Pt/C-JM相比,由于炭载体的具有高稳定性以及三维多尺度结构,MSGC担载Pt后不仅使电催化剂的电化学稳定性提高,且氧还原反应过程中传质得到显著改善.     

杂原子掺碳材料氧还原催化剂研究进展

开发替代Pt类高活性、低成本的非贵金属燃料电池阴极氧还原催化剂是实现燃料电池商业化的必由之路. 研发催化活性高,稳定性好,价格便宜的非贵金属催化剂是当务之急. 碳纳米材料,尤其杂原子掺杂的碳纳米材料有其独特的结构和催化性能而备受瞩目. 本文结合作者课题组的研究工作,综述了近年杂原子掺杂碳纳米材料催化剂燃料电池阴极氧电催化还原方面的研究进展.     

固体碱D301树脂在杂环卤代芳烃Heck反应中的应用

利用D301树脂作为碱性试剂, 在无膦配体, 低用量Pd(OAc)2催化下进行了杂环卤代芳烃与烯烃的Heck芳基化反应研究, 实验结果表明D301树脂作为固体碱不仅可使反应获得满意的收率, 而且具有良好的重复使用性能.     

The potential of MXene materials as a component in the catalyst layer for the Oxygen Evolution Reaction

MXenes are a class of 2D/layered materials which are highly conductive, hydrophilic, have a large electrochemical surface area and are easily processible into electrodes for energy applications. Since the discovery of MXenes over ten years ago, these materials have been mainly used in the preparation of electrodes for batteries and supercapacitors. However, due to their aforementioned properties, MXenes could potentially be utilised as a component in the catalyst layer for the Oxygen Evolution Reaction (OER). This opinion piece will discuss some of the recent literature in the area of hybrid catalysts consisting of various Transition Metal Oxides (TMOs) and MXenes for the OER. We will also discuss current drawbacks and future outlook in this new area of research.     

以铁的催化褪色新指示反应测定超痕量铁

本文研究了在乙酸介质中,铁(Ⅲ)催化过氧化氢氧化钙试剂羧酸钠盐的褪色反应,利用这个反应建立了超痕量铁测定的新方法。本方法的桑德尔灵敏度为2.92×10^-5μg/cm²,是目前铁的光度测定中灵敏度最高的方法之一。本方法已成功地用于饮用水、若干品种粮食和人发中超痕量铁的测定。     

不同催化体系下腈的水合反应研究进展

腈可用于构建新的碳-碳、碳-杂原子键,所得产物丰富多样.酰胺基团广泛存在于医药、农药和天然产物中,此外,酰胺还是有机合成反应中重要的中间体.在目前报道的酰胺类化合物的合成方法中,腈的水合反应已成为学术界和工业界最广泛使用的获得初级酰胺类化合物的方法之一.早期腈的水合反应中通常涉及强酸、强碱的使用,但在该类反应体系下,往...     

Thermogravimetry as a Method for Investigating the Thermal Stability of Polymer Composites

Thermogravimetry was used to investigate the effects of different inorganic functional fillers on the heat resistance of polymer matrices. The kinetic parameters of thermal oxidative degradation were shown to depend on the polymer, the chemical composition of the filler surface, the filler concentration, and the processing method, which determines the distribution of filler particles in the polymer matrix. Magnetic fillers (carbonyl iron, and hexaferrites of different structural types) were shown to be chemically active fillers, increasing the heat resistance of siliconorganic polymers. Their stabilizing effect is due to blocking of the end silanol groups and macroradicals by the surface of the filler and non-chain inhibition of thermal oxidative degradation. In the case of fiber-forming polymers (UHMWPE, PVOH and PAN), most magnetic fillers are chemically inert, but at concentrations of 30–50 vol% they increase the heat resistance of the composite. Addition of carbon black increased the heat resistance of the thermoplastic matrix. The dependence of the thermal degradation onset temperature on the kaolin concentration in the polyolefin matrix exhibited a maximum. Analysis of the experimental results demonstrated the operating temperature ranges for different composites, and their maximum operating temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamic Environments as a Tool to Preserve Desired Output in a Chemical Reaction Network

Current efforts to design functional molecular systems have overlooked the importance of coupling out-of-equilibrium behaviour with changes in the environment. Here, the authors use an oscillating reaction network and demonstrate that the application of environmental forcing, in the form of periodic changes in temperature and in the inflow of the concentration of one of the network components, removes the dependency of the periodicity of this network on temperature or flow rates and enforces a stable periodicity across a wide range of conditions. Coupling a system to a dynamic environment can thus be used as a simple tool to regulate the output of a network. In addition, the authors show that coupling can also induce an increase in behavioural complexity to include quasi-periodic oscillations.     

Ionic Liquid [bmim][BF4] as a Green Medium for Passerini Reaction

The Passerini reaction, a three-component condensation reaction of carboxylic acid, aldehyde and isocyanide constructing an α-acyloxycarboxamide in a single step, was first discovered by Passerini about 80 years ago1. Since then, this reaction has been w…     

Electrosynthesis of CuO Nanocrystal Array as a Highly Efficient and Stable Electrocatalyst for Oxygen Evolution Reaction

Electrodeposition of active catalysts on electrodes appears as a convenient approach to prepare non-noble-metal based electrocatalysts with defined micro- and nano-structures. Herein we report a new strategy of fabricating a 3-D hierarchical CuO nanocrystal array (CuO NCA) on Cu foam through a two-step sacrifice-template method. This CuO NCA possesses high conductivity, great stability, and impressive catalytic activity for oxygen evolution reaction (OER) in alkaline electrolytes. The CuO NCA can achieve a high current density of 100 mA/cm\begin{document}$^2$\end{document} at a relatively low overpotential of 400 mV for OER, which shows a better performance than other Cu-based OER catalysts and IrO\begin{document}$_2$\end{document}. The high activity of CuO NCA is well retained during a 10-h OER test at a high current density around 270 mA/cm\begin{document}$^2$\end{document}, which is about 10 times higher than the current density achieved by IrO\begin{document}$_2$\end{document} (around 25 mA/cm\begin{document}$^2$\end{document}) with the same applied overpotential. According to our best knowledge, CuO NCA is currently the most efficient and stable Cu-based electrocatalyst for water oxidation in alkaline electrolytes.