纳米金属氧化物催化剂在固体推进剂中的应用进展

综述纳米金属氧化物催化剂在固体推进剂中的应用现状,包括纳米过渡金属氧化物催化剂、纳米稀土金属氧化物催化剂和纳米复合金属氧化物催化剂,总结了目前应用中存在的问题。认为固体推进剂用纳米金属氧化物作催化剂,可获得优于非纳米催化剂的燃烧性能。     

过渡金属氧化物催化氧化甲醛的研究进展

归纳分析了单一金属氧化物、复合金属氧化物、负载贵金属、添加碱金属以及MOFs型的过渡金属氧化物催化剂在甲醛氧化方面的研究进展,指出各类过渡金属氧化物催化剂的优点与不足。对各类过渡金属氧化物催化剂的特点进行总结并展望其未来的发展方向。     

纳米粒度金属氧化物催化剂制备方法的研究进展

金属氧化物是一类重要的催化剂,在催化领域中已得到广泛的应用,将金属氧化物纳米化后,其催化性能更加优良,可以预见,纳米金属氧化物将是催化剂发展的重要方向。综述了近年来国内外金属氧化物催化剂的研究进展,讨论了纳米金属氧化物催化剂的各种制备方法,如溶胶 凝胶法、水解法、水热合成法、 微乳法、沉淀法、固相反应法、超临界干燥法、微波固相法、热分解法、燃烧合成法和撞击流反应 沉淀法等,并对各种方法的特点作了总结和归纳。     

用于CO氧化的铜基催化剂研究进展

系统地介绍了用于CO氧化的催化剂种类、反应类型和反应机理,着重对铜基催化剂(单金属氧化物、双金属氧化物、多金属氧化物)用于该反应的研究进展进行总结,分析了对催化性能产生影响的因素,并在此基础上,对铜基催化剂用于CO氧化的研究方向进行了展望。     

碳酸二甲酯和乙酸苯酯合成碳酸二苯酯催化剂研究进展

综述了碳酸二甲酯和乙酸苯酯合成碳酸二苯酯工艺路线及其反应机理,并对该反应的催化剂体系进行了系统的概述,包括均相催化剂体系(锡和钛的有机化合物等)和多相催化剂体系(MoO3和WO3等金属氧化物)。并分析了以锡、钛以及金属氧化物作催化剂时合成碳酸二苯酯的优势和劣势;指出固载化的有机锡/有机钛与其他金属氧化物的复合化合物是今后碳酸二甲酯和乙酸苯酯合成碳酸二苯酯催化剂的重要研究方向。     

低温氧化型过渡金属氧化物催化剂研究进展

汽车冷启动时催化剂床层温度低,尾气中的CO和烃类不能被传统三效催化剂有效消除。目前,非贵金属类的过渡金属氧化物催化剂用于CO和烃类的低温氧化受到了广泛关注。本文综述了近几年来国内外以Cu、Co和Mn的氧化物为主要代表的过渡金属氧化物上烃类和CO氧化的研究进展,对催化剂上界面氧空位参与氧化过程的反应机理进行了总结,展望了过渡金属氧化物催化剂用于CO和烃类低温氧化的未来研究趋势。     

铜锰氧化物催化剂制备方法研究进展

过渡金属是一类重要的催化剂,在催化领域已得到广泛应用,将过渡金属氧化后,其催化性能更加优良,可以预见过渡金属氧化物将是催化剂发展的重要方向。综述了近年来国内外铜锰金属氧化物催化剂的研究进展,讨论了铜锰金属氧化物催化剂的各种制备方法,如浸渍法、水热合成法、共沉淀法、固相法和溶胶-凝胶法等,对各种制备方法的特点进行总结和归纳,并展望铜锰氧化物催化剂的发展前景。     

金属氧化物催化苯酚-甲醇气相C-烷基化的研究进展

综述了金属氧化物催化体系下的苯酚-甲醇气相C-烷基化反应研究进展,比较了苯酚-甲醇气相邻位C-烷基化合成邻甲酚和2,6-二甲酚的工艺方法和催化体系,重点探讨了金属氧化物催化体系下苯酚-甲醇连续固定床气相烷基化法的研究现状。同时,对单一组分和多组分金属氧化物的不同C-烷基化反应活性进行了比较,在此基础上探讨了催化剂酸碱性质与反应性能的关系、催化剂失活原因、苯酚和甲醇气相邻位C-烷基化的反应机理等问题,并对今后更高效环保的金属氧化物催化剂的研究方向提出了展望,提出了纳米尺度催化剂和生物质催化剂等研究热点。     

金属氧化物脱硝催化剂钾、钠中毒及抗中毒研究进展

金属氧化物脱硝催化剂是NH_3选择性催化还原技术(NH_3-SCR)中应用最广泛的催化剂,但在使用过程中易受到碱金属钾、钠的影响,使其脱硝活性下降甚至失效。本文介绍了不同金属氧化物催化剂进行脱硝时的反应机理,以及存在钾、钠时金属氧化物催化剂的物理和化学失活机理,系统介绍了催化剂抗钾、钠中毒改进的技术方法,即元素掺杂改性、改变载体形状、硫酸化以及酸性气氛等。     

不同形貌金属氧化物的制备及其在工业催化反应中的应用

金属氧化物作为一类重要工业催化剂,广泛应用于合成氨工业、能源化工、精细化工等重要的工业生产过程。金属氧化物的形貌对其性能有重要的影响,具有特定形貌的金属氧化物催化剂因其结构上的优势,使其在许多方面表现出不同于常规块体材料的独特性能,成为当前材料科学领域的研究热点。本文总结了不同形貌的金属氧化物的制备方法、生长机制及其结构特性,聚焦于金属氧化物在氧化反应、加氢反应以及蒸汽重整反应中的最新研究进展。最后,进一步讨论了金属氧化物催化剂未来的发展趋势以及面临的挑战,并提出了解决这些问题的有效方案。     

Factors controlling the mode by which a catalyst operates in the graphite-oxygen reaction

Variations in the catalytic action of metals on the graphite-oxygen reaction is discussed in terms of differences in the wetting characteristics of the catalyst on the graphite edge regions. It is shown that metals which readily form oxides exhibit a strong interaction with the oxygenated graphite surface and attack by the edge recession mode. In contrast, catalysts which remain in the metallic state have a weaker interaction with the graphite and function by a channeling action. An explanation for the catalytic inactivity of certain metals in this reaction is also presented.     

纳米金属氧化物去除水体重金属的研究进展

简要介绍了用于吸附水体重金属的几种纳米金属氧化物,包括:纳米铁氧化物、纳米锰氧化物、纳米铝氧化物、纳米钛氧化物、纳米锌氧化物、纳米镁氧化物、纳米铈氧化物以及纳米金属氧化物复合材料,讨论了各种纳米金属氧化物处理水体重金属的优缺点,并展望了其应用前景。     

Design considerations for groundwater remediation using reduced metals

Use of reduced metals has attracted much attention since it possesses a great potential for eliminating reducible contaminants in groundwater such as heavy metals and chlorinated compounds. However, products of metal-mediated reactions for many chlorinated hydrocarbons have not clearly been identified. In addition, consumption of the metals, generation and release of metal ions, formation of insoluble metal oxides and hydroxides on the clean metal surface, and rise of pH inevitably accompany the reactions. Due to these properties of metal-mediated reactions, the reaction rate could decrease as the reaction proceeds, and effluent quality could decay. It was shown in this study using chlorine mass balance and GC analysis that chloroform is formed from carbon tetrachloride by reduced iron. It is also well-known that nitrate is reduced mostly to ammonia by metals, which indicates that the metal process is inappropriate for denitrification of nitrate-contaminated aquifers. These results indicate that groundwater remediation using metal process requires careful consideration for the safety of reaction products. It was also shown that mixing rate strongly affects reaction rate since metal-mediated reaction occurs on the surface of metals. In addition, reaction rate was decreased due to metal hydroxide deposition on the surface of metal granules that was seen by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. Generation of iron ions (consumption of reduced iron) released from reduction of zero-valent iron was also shown by using an ion chromatograph (IC). In this study, some methods were suggested to solve the above-mentioned problems. Acid washing appeared effective for removing corrosion products on the surface of metal granules, by which a reduction rate could be maintained high for an extended time of reaction. Use of iron sulfide decreased an extent of pH rise during metal-mediated reaction; thereby precipitation of insoluble metal (hydr)oxides is expectedly decreased. It was also shown that inexpensive iron scrap instead of fine metal powders can be used for metal processes.     

Solvothermal Reaction of Rare-Earth Metals in 2-Methoxyethanol and 2-Aminoethanol

In a previous paper, we reported that the reaction of cerium metal in 2-methoxyethanol yielded a transparent colloidal solution of ultrafine (2 nm) ceria particles [M. Inoue, M. Kimura, T. Inui, Chem. Commun ., 957 (1999)]. In this paper, the solvothermal reaction of other rare-earth metals in 2-methoxyethanol has been examined. Reactions of Sm and Yb metals in 2-methoxyethanol at 300°C yielded transparent colloidal solutions of Sm₂O₃ and Yb₂O₃ particles. However, the reaction of rare-earth metals of Y, Eu, Gd, and Tb in 2-methoxyethanol at 300°C resulted in recovery of the starting materials. Transparent colloidal solutions of the oxides of these elements were obtained by reaction in the presence of a small amount of acetic acid. The solvothermal reaction of rare-earth metals in 2-aminoethanol was also examined.     

Mechano-catalytic overall water splitting on some mixed oxides

Simple transition metal oxides such as NiO, Co₃O₄, Fe₃O₄ and Cu₂O were found to catalytically decompose water into H₂ and O₂ by mechanical energy. The reaction is regarded as “mechano-catalytic” overall water splitting” and is a quite novel catalytic reaction. In this paper, some general aspects on the mechano-catalytic overall water splitting are reviewed on simple oxides. In addition, recent results on the mechano-catalytic activity of a groups of mixed oxides, wolramite-type oxides with a formula of ABO₄ (A=Fe, Co, Ni and Cu, etc., B=W, Mo), are shown. AWO₄ (A=Fe, Co, Ni and Cu) decomposed water into H₂ and O₂ under the supply of mechanical energy, indicating that mechano-catalytic overall water splitting proceeded on wolframite-type compounds containing 3d-transition metals. AMoO₄ (A=Fe, Co, Ni) also decomposed water into H₂ and O₂ under supply of mechanical energy. The reaction properties on wolframite-type oxides are discussed.     

Application of Radioactive Tracers in Dehydrocyclization Reaction Mechanisms

The passage of paraffins and olefins with six or more carbon atoms over catalytic metals and metal oxides can lead to ring closure, Although this reaction was noticed first by three independent groups of Russian workers [1-3], it gained industrial importance through the work of Grosse and co-workers [4] in making toluene from heptane over alumina-supported metal oxide catalysts.     

钯基乙炔选择性加氢催化剂研究进展

催化选择加氢去除乙烯中微量乙炔是石化工业重要的反应过程,工业钯基催化剂选择性低、催化剂使用寿命较短。本文综述了近年来国内外乙炔选择性加氢钯基催化剂的研究进展。主要探讨了过渡金属、金属氧化物与非金属配体助剂能调变钯粒子空间结构,隔离分散钯粒子并与钯粒子产生电子效应;阐明了钯粒子尺寸与织构形貌的调控能改变钯的晶面结构,影响钯对乙烯的吸脱附和对氢气的活化与解离性能;评述了单一氧化物、复合金属氧化物、碳材料等载体为催化剂提供合适的表面酸碱性并加强了与活性中心之间的相互作用,稳定钯粒子抑制其发生迁移与团聚。提高乙烯选择性与催化剂稳定性是该研究的重点与难点,负载型钯基催化剂的发展方向是构建高分散钯粒子,并在反应过程中保持稳定。     

添加物对MgO－Cr_2O_3捣打料强度的影响

研究了在ＭｇＯ－Ｃｒ２Ｏ３捣打料中添加金属粉和氧化物对其强度的影响。试验结果表明，同时加入金属粉和氧化物可获得强度较高的捣打料     

异丙苯催化氧化催化剂研究进展

异丙苯氧化反应是石油化学工业中重要的反应过程,传统的异丙苯氧化工艺是以少量的氧化产物过氧化氢异丙苯作为引发剂的无催化氧化工艺,存在效率低和安全性差等缺陷。几十年来,研究者对异丙苯催化氧化工艺进行了广泛研究,开发的催化剂类型主要有碱金属或碱土金属催化剂、金属氧化催化剂、过渡金属离子有机络合物催化剂、N-羟基邻苯二甲酰亚胺类催化剂、负载型催化剂、金属及合金催化剂和中孔分子筛催化剂等。其中,改性MgO催化剂、Ag及Ag-Au合金催化剂和负载过渡金属杂原子的中孔分子筛催化剂表现出较优越的催化性能,具有较好的开发前景。但迄今为止报道的各类催化体系还不能彻底解决传统氧化工艺的固有问题,开发具有高活性、高选择性和高稳定性的环境友好催化体系是今后研究的重点。