甲烷二氧化碳重整镍基催化剂的研究进展

甲烷二氧化碳重整制合成气是对甲烷、二氧化碳这2种温室气体资源化利用的有效途径。近年来,研究最多的领域是关于该反应催化剂的开发,其中镍基催化剂的研究最广泛。为了全面了解甲烷二氧化碳重整反应及镍基催化剂的应用,介绍了甲烷二氧化碳重整反应的热力学研究及机理;分析了镍基催化剂的积碳原因及消碳途径;论述了镍基催化剂的载体、助剂、制备方法对催化剂催化性能的影响;最后对镍基催化剂未来的研究方向进行了展望。热力学研究结果显示,高温低压有利于甲烷二氧化碳重整反应的进行;针对甲烷二氧化碳重整反应的机理尚没有统一的定论,不同催化剂应用于该反应,作用机理也不同;镍基催化剂积碳主要由甲烷裂解反应、一氧化碳歧化反应及一氧化碳氧化还原反应产生,为解决积碳问题,从催化剂方面着手,通过调控催化剂性质抑制积碳;载体性质、助剂类型、制备方法不同会对镍基催化剂产生不同作用;镍基催化剂距离工业化应用还有一段距离,在未来发展中可优化催化剂制备条件,深入探究催化剂的积碳机理,理论与实践相结合,进一步探究镍基催化剂的性能。     

甲烷空气催化部分氧化制含氮合成气的研究

采用常规的浸渍法制备了镍基催化剂和经过镧改性的镍基催化剂,研究了甲烷催化部分氧化制备含氮合成气的催化功能,结果说明,镍含量在8％时催化活性达到最好,同时加入镧进行改性后催化剂的活性和选择性有所提高;该催化剂对甲烷空气催化部分氧化制合成气在常压下具有较高的转化率,随压力升高,转化率明显下降,并且积极严重,通过向体系加入H2O和CO2可以提高加压条件下甲烷的转化率并抑制催化剂积碳,还可以获得H2／CO接近2的合成气,满足合成液体燃料的要求。     

煤制代用天然气镍基催化剂研究进展

综述了镍基甲烷化催化剂的研究现状。重点阐述了助剂、载体以及制备方法对催化剂催化性能的影响。在保持镍基甲烷化催化剂催化活性的基础上,提高催化剂的耐高温、抗积炭和抗硫中毒的性能是镍基甲烷化催化剂的主要研究方向。在保持催化剂良好性能的基础上,降低镍基甲烷化催化剂的生产成本对于其在工业生产中的应用具有重要意义。     

甲烷空气催化部分氧化制含氮合成气的研究

采用常规的浸渍法制备镍基催化剂,研究了甲烷空气催化部分氧化制备含氮合成气的催化性能,得到了镍含量在8％时部分氧化活性最佳;加入镧助剂使催化剂的活性和选择性达到95．3％和97．5％,通过向体系加入H2O和CO2,可以提高加压条件下甲烷的转化率并抑制催化剂积炭,可以获得n(H2):n(CO）接近２的合成气;催化剂连续使用500h性能稳定。     

助剂对煤基合成气甲烷化反应用镍基催化剂的促进作用

助剂促进的合成气甲烷化反应用镍基催化剂具有反应活性高、使用寿命长以及甲烷选择性高等优点,被广泛应用于煤基合成气甲烷化制替代天然气反应中。本文重点介绍了贵金属、碱土金属、稀土金属以及过渡金属助剂等对活性镍基催化剂的分散度、还原度、双金属合金协同效应、镍基催化剂结构稳定性及其对合成气甲烷化反应速率和产物选择性的影响。较系统地分析了这些助剂改性镍基催化剂的作用机制。提出了非贵金属助剂以及复合助剂将是合成气甲烷化用镍基催化剂助剂研发的发展方向,旨在为煤基合成气制替代天然气甲烷化催化剂的研发提供借鉴和参考。     

1,2-环己二醇脱氢制备临苯二酚催化剂的失活与再生

在1,2-环己二醇脱氢制备邻苯二酚的反应中,镍基催化剂表现出良好的催化活性和选择性.但是镍基催化剂在反应过程中活性逐渐降低,通过XRD、BET物理吸附等物性表征表明,Ni氧化变成NiO,Ni微晶长大,Ni和助剂NaSO4流失等不是引起镍基催化剂失活的主要原因,而镍基催化剂表面活性位在反应过程中积炭和吸附部分产物可能是导...     

稀土La改性的非晶态Ni基催化剂CO_2甲烷化催化性能的研究

本文采用固定床反应装置考察了稀土镧改性的非晶态镍基催化剂二氧化碳甲烷化催化反应活性。实验结果表明:氧化镧的添加,提高了非晶态镍的晶化温度,阻止了镍的聚集,提高了镍的分散度,从而提高了二氧化碳甲烷化的活性和稳定性。     

尿素电氧化镍基阳极催化剂的研究进展

近年来,尿素电氧化法处理富含尿素的工业废水和生活污水得到了广泛关注。在尿素电氧化过程中,催化剂是决定尿素氧化效率和实用性的关键材料。非贵金属镍不但对尿素电氧化反应表现出较高的催化活性,而且廉价易得,近年来成为研究热点。本文在简要介绍碱性环境中镍基催化剂氧化尿素机理的基础上,综述了最近尿素电氧化催化剂的研究进展,并结合本课题组的工作从镍基金属催化剂、镍基氢氧化物催化剂、镍基氧化物催化剂和负载型催化剂4个方面做了详细的评述。文中提出当前尿素电氧化催化剂存在催化活性较低、电流密度较小、起始电位较高等问题,未来尿素电氧化催化剂将朝向改变镍基催化剂的形貌和组成等方向发展。     

甲烷二氧化碳氧气氧化重整的研究

在镍基催化剂化的甲烷二氧化碳重整反应中加入氧气使得热性的甲烷选择性氧化与吸热的二氧化碳重整责任中反应能够同时进行。实验结果表明，氧气的加入降低了反应温度，同时还可以在一定程度上调节Ｈ２ＣＯ比。良好的催化剂稳定性可能是由于镍粒子在表面镧氧化物中的分布的结果。     

宽温型镍基甲烷化催化剂制备及催化性能

利用挤条成型及等体积浸渍法制备了负载型镍基甲烷化催化剂。通过H₂-TPR等表征方法对催化剂进行表征,研究了MgO对镍基催化剂中NiO与载体Al₂O₃相互作用力的影响。催化剂活性评价表明,助剂MgO在甲烷化反应中对CH₄选择性具有明显的促进作用。考察了催化剂的高温稳定性,并对镍基催化剂的低温失活现象进行了研究。     

Titanhaltige Molekularsiebe als Katalysatoren für selektive Oxidationsreaktionen mit Wasserstoffperoxid

Titanium Containing Molecular Sieves as Catalysts for Selective Oxidation Reactions with Hydrogen Peroxide Titanium silicalite (TS-1) is known to be a highly-efficient and selective redox molecular sieve that has been found to catalyze a range of synthetically useful oxidation reactions with hydrogen peroxide under mild conditions. Among these reactions which are often influenced also by the shape-selective properties of the Ti-containing molecular sieve are olefin epoxidation, the oxidation of alcohols to carbonyl compounds, aromatic hydroxylations and ammoximation of cyclohexanone to cyclohexanone oxime. A critical review on the present literature on TS-1 catalysts and further Ti-containing molecular sieves is given mainly focused on the questions connected with the identification of the catalytic active titanium species and the mechanism of some of the reactions. Therefore, the procedure of the synthesis of TS-1 as well as the results obtained from the most of the physico-chemical investigations are analyzed. There are no final correlations to realize between the parameters of the synthesis, the results of characterization and the catalytic properties of TS-1.     

典型碳氢化合物水蒸气重整制氢研究进展

  烃水蒸气重整是目前获取氢能源的重要方法之一,而甲烷、汽油和柴油作为典型烃类原料可满足于不同规模氢能源的需求。本文重点从催化剂、反应工艺和反应机理及动力学三个方面对甲烷、汽油和柴油蒸汽重整制氢进行介绍和评述。指出甲烷重整制氢镍基催化剂的改性和反应器设计以及反应条件的优化是其必然的发展趋势,汽油和柴油重整制氢催化剂未来设计必须具备高抗硫性和抗积炭性。此外,需加强甲烷、汽油和柴油蒸气重整制氢的机理和动力学研究。     

Innovative Katalysatoren zur oxidativen Dehydrierung in der Gasphase – Metallische Kurzfasern

Innovative Catalysts for Oxidative Dehydration Reactions in the Gas Phase – Metallic Short Fibres The catalytic activity of metallic short fibres with chosen alloy composition and texture was investigated in the oxidative dehydration (ODH) of propane to yield propene, and of isopropanol to yield acetone. The short fibres were synthesised using a melt extraction process and the properties of the fibres were intensely characterised. A correlation between the structure and the catalytic activity of the material was established. Thus, light‐optical microscopic‐, DSC‐, XRD‐, REM‐ and EDX‐methods were used to characterise the fibres. Selective results of the dependency of the temperature on the propane conversion are presented in this work. A yield of more than 35 % propene is obtained at a propane conversion of 50 %. The ODH of isopropanol to acetone occurred with attractive yields of over 80 %. The results demonstrate the high innovative potential of the metal fibre materials.     

Performance of a ceramic frit anti-oxidation coating on a MgO-C refractory brick

In steel production, ladles must be preheated to minimize the heat loss of the steel melt, prevent thermal shock of refractory bricks (MgO-C), and to maximize the lining life of ladle. Partial oxidation of MgO-C bricks begins in the graphite bond during the preheating. Oxidation of graphite bond also causes a decrease in performance of the bricks because of an increase in the brick porosity. In this article, coating on a MgO-C brick surface by a ceramic film to protect against carbon oxidation was studied. Coated and un-coated bricks were heated at 1200 °C, cooled to room temperature, then the brick properties investigated. The oxidization resistance properties of brick with coating were much better than those without coating, which should lead to longer refractory service life.     

Metal-requiring and non-metal - requiring catalysts in the autoxidation of methyl linoleate

During the autoxidation of methyl linoleate, peroxide-containing substances are formed which, when added to unoxidized methyl linoleate, will catalyze oxygen uptake. Materials active only in the presence of added metal ions (MCs) were not inactivated during aerobic thin-layer chromatography on silicic acid or alumina but were selectively inactivated by treatment with triphenylphosphine. Catalysts not requiring added metal ions for activity (NCs) are not affected by triphenylphosphine, but the catalytic activity is lost during aerobic thin-layer chromatography. Autoxidized methyl linoleate was separated into four peroxide-containing fractions by elution from a silicic acid column with hexane-diethyl ether mixtures. Each fraction was found to contain both MCs and NCs. Presented at the 4th International Symposium on Metal Catalyzed Lipid Oxidation, London, April 1975.     

Preparation of bifunctonal catallysts

Catalyzed reactions are usually a combination of various reaction pathways that require Catalysts to possess more than one chemical function. These reaction types and Catalyst functions are reviewed and bifunctionality of Catalysts is exemplified in the ensemble control effect for oxidation of carbons to CO/CO₂, double redox oxide Catalysts for partial oxidation of methane, base-hydrogenation Catalysts for methanol and higher alcohol synthesis as well as the water gas shift reaction, hydrogenation-CO insertion Catalysts for higher alcohol synthesis, and acid- hydrogenation Catalysts for the synthesis of ethers.     

Pt–Pd bimetallic catalysts for methane emissions abatement

Bimetallic Pd–Pt catalysts with constant 2 wt% metal loading and varying Pt/Pd ratios were prepared, characterized and studied in the catalytic combustion of methane at low temperature under lean conditions in view of their use for CH₄ abatement from lean-burn NGV heavy duty vehicles exhausts. The influence of mild steam ageing featuring long-term use of the catalysts was also addressed together with their tolerance to H₂S. Catalysts were characterised by Transmission Electron Microscopy and Temperature Programmed Oxidation experiments. Experimental data agreed to suggest an interaction between Pd and Pt in Pd-rich catalysts, thus explaining their improved catalytic activity, even after mild ageing, compared to reference Pd/Al₂O₃. This interaction has no effect on the sulfur tolerance.     

Über den Einfluß von Licht auf den oxydativen Verderb von Speiseölen III: Abhängigkeit der Oxydationsgeschwindigkeit vom Sauerstoffpartialdruck und der Lichtintensität

Effect of Light on the Oxidative Deterioration of Edible Oils III: Effect of Partial Pressure of Oxygen and Intensity of Light on the Rate of Oxidation An apparatus is described for the measurement of oxygen consumption during oxidation of edible oils. Oxidation can be followed in this apparatus under the action of light of any desired intensity and spectral composition, and at various O₂-pressures. Sunflower, peanut and soybean oils were chosen as substrates. The characteristic curves representing oxygen uptake versus time during photo-oxidation showed an unique behaviour of soybean oil; its photo-oxidation proceeded in two phases. With decreasing pressures, a noticeable decrease in the rate of oxidation of the aforesaid oils is observed only at pressures as low as 10-20 mm Hg; up to this region the effect of oxygen pressure is insignificant. The effect of light intensity on the rate of oxidation shows for soybean oil a linear function in the first phase, and a square root function for sunflower oil, and peanut oil and for soybean oil in the second phase.     

Transient simulation of an autothermal reformer

For the safe and trouble-free operation of an autothermal reformer there is a need of knowledge about the interactions between the reactions and the fluid dynamic. To answer technological questions about the reactors operating response a model was developed that allows the simulation of different consecutive states like load changes and start up procedures. The presented model was created to support the research work performed with the High Pressure Partial Oxidation test plant (HP-POX) at the Institute for Energy Process Engineering and Chemical Engineering (IEC) of the Technical University Bergakademie Freiberg (Freiberg, Germany), a joint venture with the Lurgi AG.     

Partialsynthesen von Cardenoliden und Cardenolid-Analogen. IX. Cardenolidderivate mit einer ungesättigten Aldehydfunktion am Lactonring

Partial Syntheses of Cardenolides and Cardenolide Analogues. IX. Cardenolide Derivatives with an Unsaturated Aldehyde Function at the Lactone Ring Oxidation of 22-allyl-digitoxigenin-3-acetate [ 1 ] and 22-allyl-digitoxin ( 4 ) with selenium dioxide resulted in the introduction of an oxygen function into the unsaturated C-22 substituent of the cardenolide molecule. The isolated compounds were the 22-(3′-oxo-prop-1′-en-1′-yl)-derivatives 3 and 6 of 1 and 4 , respectively. The molecular biological activity of 3 was estimated to be about six times higher than that of the parent compound 1 .