Pd catalysts supported on silicon nitride for the combustion of methane: Influence of the crystalline and amorphous phases of the support and of the preparation method on the catalytic performances

Non-oxide refractory materials, such as silicon nitride having high thermal stability and thermal conductivity can be used as catalytic supports. The influence of the Si₃N₄ support nature and of the chemical compounds used for preparations on the physical-chemistry and catalytic properties of the palladium systems in the total oxidation of methane was investigated. A strong influence of the phase composition and the crystalline state of supports on the catalytic properties in the total oxidation of methane of the Pd catalysts was found. The activity of Pd catalysts increases with the -Si₃N₄ content and crystallization state of the support. The catalytic activity of Pd/-Si₃N₄ is also strongly affected by the preparation procedure. The Pd/-Si₃N₄ catalyst obtained by aqueous impregnation is less active and less stable. It was proposed that if water is used as an impregnation solvent, the surface acid-based properties of Si₃N₄ support and/or of the Pd active phase are irreversibly damaged. Pd supported on -Si₃N₄, prepared by impregnation of the Pd precursors in toluene solutions are found to be the most active and stable under reaction conditions.     

印染废水回用处理技术研究

为将污水回用于生产,降低生产成本,采用连续膜过滤系统(CMF)-活性炭吸附处理工艺对某印染厂污水处理站排水进行回用处理研究.结果表明:利用CMF和活性炭单独处理后,出水均不能达到印染工艺用水要求;联用后,CMF-活性炭工艺优于活性炭-CMF工艺的处理出水效果,出水Fe、Mn去除率达到100%,总硬度0.325 mg/L,色度为4度,浊度0.2 NTU,pH 7.0,达到工艺用水要求.对CMF-活性炭处理工艺的工程投资和运行成本进行分析,该处理工艺在印染行业有相当的应用价值.     

基于旋光效应测量溶液浓度的实验改进

对旋光仪实验装置结构改进,把旋光溶液浓度用电信号测量表示.通过理论分析与实验,该改进的方法对较小的旋光角测量精度有显著的提高,并测量了低浓度的蔗糖溶液.     

以非水溶性肥料或矿物进行灌溉施肥的新方法

介绍一种灌溉施肥的新方法。采用非水溶性肥料或矿物(低品位活性磷矿、特殊玻璃网络结构的钙镁磷肥、低交联度硅钙网络冶炼炉渣及活性有色金属矿尾砂等)通过在专利设备——液升式灌溉施肥反应器中加入活化剂反应,就地制备含H2PO4-、Ca2+、Mg2+、Fe2+、Zn2+、Mn2+、BO33-及水溶性硅酸的营养液,可直接用于灌溉施肥或叶面喷施。     

提高活性污泥浓度降低外排污水化学需氧量

活性污泥浓度是影响外排污水化学需氧量的主要原因 ,与活性污泥浓度有关的因素有 :曝气效果 ;活性污泥回流情况 ;隔油效果等。处理后污水化学需氧量可以达到 :COD <6 5mg/L。     

对有潜力作为生物农药物质的新研究

介绍了一些已知有非农药用途活性的生物发酵液和其活性物质的农药活性的最新研究，其中一些物质对病虫害的作用可与商业化制剂媲美。指出对已有各种用途天然源物质进行生物农药开发研究是开发农药的一个重要的途径。     

浅谈活性氧化铝对双氧水生产的影响

活性氧化铝在蒽醌法双氧水生产工艺中,主要作用是吸附工作液中夹带的碱以及再生工作液在氢化,氧化反应过程中因副反应产生的副产的,在双氧水生产过程中,怎样选择和用好活性氧化铝,对双氧水的产量和质量极为重要。     

路易氏碱在阴离子聚合领域中的应用 Ⅵ 溶剂极性经验参数的应用

根据作者的大量实验数据和分析文献资料,综合和评述了以路易氏碱的过渡态能来代替它传统的给电子指数、介电常数或永久偶极矩,作为衡量它在阴离子聚合中与活性种作用的强弱标准;此外,还介绍推导了在上述领域中路易氏碱的过渡态能与聚合反应动力学与热力学常数之间的一系列定量关系式     

A Critical Assessment of Li/MgO-Based Catalysts for the Oxidative Coupling of Methane

Li/MgO is one of the most frequently investigated catalysts for the oxidative coupling of methane. Besides catalytic testing, it is also a suitable system to perform surface science experiments and quantum chemical calculations, which is not possible for many other active catalysts. However, the real structure of Li/MgO, the nature of the active center and the structure - activity relationship remain unclear, despite all the research that has been done. The aim of this review is to summarize the available knowledge on Li/MgO to structure and accelerate and improve the ongoing work on this catalytic system.     

UV polymerization‐based surface modification technique for the production of bioactive packaging

The term bio‐active packaging refers to a packaging material that has been modified by the attachment or immobilization of bioactive components on the food contact surface. This article describes a novel, economical, and feasible technique for embedding bioactive components in energy curable food contact resins. While the technique is versatile and potentially applicable to any antimicrobial or bioactive compound; the proof of concept discussed in this article has focused on enzyme immobilization. Glucose oxidase (GOx) and catalase were used as representative enzymes. These oxidoreductases are very sensitive to inactivation by extrinsic factors and therefore present a challenging model for immobilization. Embedding of activity occurred via UV polymerization of commercial polymer coatings. The efficiency of immobilization and the performance of bioactive packaging were tested in both food simulants and actual food products. In both cases immobilization resulted in food contact surfaces with high retained enzyme activity as demonstrated by oxygen removal. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hydrogenation of nitrotoluenes controlled by the electrochemical potential of the catalyst

The hydrogenation of 2-nitrotoluene, 2,4-dinitrotoluene and 2,4,6-trinitrotoluene on Pd/C, Pt/C and Ni/SiO₂ catalysts was investigated in a liquid phase batch reactor at pressures between 0.4 and 2.5 MPa. The reaction was controlled by regulating the substrate supply in such a way that the electrochemical potential of the catalyst and, consequently, the surface concentration of active hydrogen was kept at a constant level. The observed hydrogenation rate dependence on the concentration of active surface hydrogen shows that the hydrogen activation is at least one of the rate determining steps. Additionally, controlling the reaction by the potential of the catalyst allows one to prevent dangerous feed concentrations and fast deactivation, too.     

Investigations on the Changes of Biological Degradability of Single Substances Induced by Ozonation

On the basis of our studies it can be demonstrated that toxic or difficultly degraded substances can be converted, by means of ozonolysis, to biologically active groups of substances. An excess of ozone of 3–6 g 0₃/g DOC is however necessary. Hater works generally employ doses of 1–2 g O3/ g DOC. This may be the reason for the observed destruction of biological activities in carbon filters since at low doses the dissolved substances may be only partially oxidised or poorly degradable intermediate products are formed. From this point of view the ozonolysis of some model compounds was performed. The reaction of aniline, bezene–sulfonicacid, 4–chloro–o–cresol , 2–nitro–p–cresol and humicacid with ozone show that after low ozone doses (1 g 03/g DOC) the products formed are not biodegradable as in the case of aniline (BOD5/COD=0,05) or that the intermediate products are hardly easier to degrade than the initial substances. B0D5/C0D values of 0,05 – 0,25 were found.The reactions of ozone with the model compounds and the properties of the oxidation products are described.     

The oxygen activated by the active vanadium species for the selective oxidation of benzene to phenol

The activation of oxygen is a key step for the selective oxidation of benzene to phenol and the reason is discussed. The active oxygen species is produced from molecular oxygen in a so-called “reductive activation” process. The vanadium oxide supported on alumina was pre-reduced by hydrogen or ascorbic acid to lower valence vanadium species acting as reduction source and the activity is investigated in the reaction. It is found that the V⁴⁺ valence vanadium (VO²⁺) is effective for the reaction from the characterization of catalysts by XPS.     

重力作用下甲烷催化部分氧化积炭特性数值分析

为了研究微尺度下甲烷催化部分氧化反应在重力作用下的反应特性,考察了定C/O比情况下各个壁面的积碳量随着壁温和催化剂活性位密度变化的特性。研究结果表明：在壁温和C/O比一定,催化剂的活性位密度为1.66 mgmol/m2时,甲烷转化率和出口氢气的质量分数达到最大值,分别为99.10%和12.39%;重力的存在,使得沿重力方向的壁面积碳量增加,重力反方向的壁面积碳量减少,在温度低于1500K时,沿壁面的积碳量随着催化剂活性位密度的增加而降低,当温度在1500K时,积碳量基本为零。     

低压甲醇羰基化制醋酸用Ni系催化剂及其制备工艺

介绍了用于低压甲醇碳基化制醋酸的Ｎｉ系催化剂进展概况。讨论了浸渍法制备Ｎｉ催化剂的工艺条件：催化剂中Ｎｉ含量以２．５％为宜；添加助剂和选择性能好的载体可提高Ｎｉ系催化剂的活性，助剂以Ｍｏ、Ｃｏ居多，载体以活性炭和碳分子筛为佳。在碳基化反应中，加入助催化剂（如碘甲烷）和氢气可提高催化剂的活性和选择性。提出了Ｎｉ系催化剂开发的两个主要方向。     

氨水脱硫液质量对H2S吸收的影响

研究了H2S吸收液中酸性杂质对吸收平衡的影响，研究表明，H2S在脱硫液中的溶解量随着活性氨的增加而提高，随杂质含量的增加而减少，对于酸性物较多的吸收液，应相应提高总氨量，以提高脱硫液中的活性氨含量。     

New Perspectives in the Study of Intestinal Inflammation: Focus on the Resolution of Inflammation

Inflammation is an essential physiological process that is directed to the protection of the organism against invading pathogens or tissue trauma. Most of the existing knowledge related to inflammation is focused on the factors and mechanisms that drive the induction phase of this process. However, since the recognition that the resolution of the inflammation is an active and tightly regulated process, increasing evidence has shown the relevance of this process for the development of chronic inflammatory diseases, such as inflammatory bowel disease. For that reason, with this review, we aimed to summarize the most recent and interesting information related to the resolution process in the context of intestinal inflammation. We discussed the advances in the understanding of the pro-resolution at intestine level, as well as the new mediators with pro-resolutive actions that could be interesting from a therapeutic point of view.     

Initial activation of platinum-rhodium gauzes for the catalytic oxidation of ammonia

Studies have been made of the activation of platinum-rhodium gauze catalysts for the oxidation of ammonia, using optical microscopy, electron probe microanalysis (EPMA), and electron spectroscopy to characterize the surfaces. The initial washing procedure is found to remove calcium and to reduce carbon residues on the surface, as a result of which the catalyst is active at lower temperatures. Subsequent activation in a hydrogen flame or in oxygen causes surface rearrangements and results in rhodium enrichment at the surface: this latter trend is partially reversed in the early stages of the oxidation of ammonia. Water vapor is found to deactivate the activated gauze.     

阴离子聚合体系活性种聚合活性的探讨

讨论了非极性和极性溶剂中有机锂活性种的活性，指出添加少量极性添加剂或在极性溶剂中，由于溶剂化作用，有机锂活性种的聚合活性有所降低。     

负载型Au催化剂的研究进展

金一直被认为是一种相对惰性的化学元素，但是近年来的研究发现，金催化剂对于CO及VOCs的低温氧化表现出很高的催化活性。本文综述了近年来金催化剂研究的进展情况，系统介绍了金催化剂的制备方法，以及金催化剂在不同反应中的催化活性和反应的机理。