HPO法合成羟胺催化剂Pd+Pt/C的制备研究

本文对NO₃^－加氢还原制羟胺的Pd+Pt/C催化剂进行了研究,考察了载体活性炭来源、预处理条件、Pt添加量、助剂种类和用量等因素对催化剂性能的影响。研究表明选择大、中孔比例高(≥70％)的活性炭做载体,并进行适当的表面处理,可改善活性组份Pd、Pt的分散度和提高对产物羟胺的选择性。添加一定量Pt(≤20%)可显著提高催化剂活比。XRD物相分析表明还原反应活性中心可能是Pd-Pt合金。实验还确定了GeO₂为合适的助剂,其最佳添加范围为2-4mgGeO₂/g.cat     

Half‐Sandwich Scorpionate Vanadium,Iron and Copper Complexes: Synthesis and Application in the Catalytic Peroxidative Oxidation of Cyclohexane under Mild Conditions

The new half‐sandwich scorpionate complexes [hydridotris(1‐pyrazolyl)methane]vanadium trichloride, ([VCl₃{HC(pz)₃}] 1 (pz=pyrazolyl), [tris(1‐pyrazolyl)methanesulfonate]vanadium trichloride, [VCl₃{SO₃C(pz)₃}] 2 , [hydrido(1‐pyrazolyl)methane]iron dichloride, [FeCl₂{HC(pz)₃}] 3 , lithium [tris(1‐pyrazolyl)methanesulfonate]dichloroferrate, Li[FeCl₂{SO₃C(pz)₃}] 4 , and [tris(1‐pyrazolyl)methanesulfonate]copper chloride, [CuCl{SO₃C(pz)₃}] 5 were synthesized, characterized and shown to act, as well as the related (tripyrazolylmethane)copper dichloride, [CuCl₂{HC(pz)₃}] 6 , as selective catalysts (or catalyst precursors) for the peroxidative oxidation (with hydrogen peroxide) of cyclohexane to cyclohexanol and cyclohexanone, under mild conditions (at room temperature and using an aqueous solution of H₂O₂). The iron complexes are the most active ones (reaching TON values up to ca. 690), the effects of a variety of factors are reported and the reaction is shown to proceed via both C‐ and O‐centred radical mechanisms, conceivably involving a metal‐based oxidant.     

Synergistic Effect of a Palladium‐on‐Carbon/Platinum‐on‐Carbon Mixed Catalyst in Hydrogen/Deuterium Exchange Reactions of Alkyl‐Substituted Aromatic Compounds

We have found a synergistic effect in the H‐D exchange reaction of alkyl‐substituted aromatic compounds using the Pd/C‐Pt/C‐D₂O‐H₂ system. This system would lead to fully H‐D exchange results even on the sterically hindered sites which were only low‐deuterium incorporated by Pd/C or Pt/C independently. Since the reaction was general for a variety of aromatic compounds, it could be applied to the deuteration of dianiline derivatives as raw materials for polyimides.     

Bulk and Surface Properties of a VPO Catalyst Used in an Electrochemical Membrane Reactor: Conductivity-, XRD-, TPO- and XPS-study

In the first part of this work, the electrical conductivity of vanadium phosphorous oxide (VPO) catalyst was investigated by means of the 2-probe EIS method. The VPO showed an extremely low conductivity at low oxygen partial pressure, which is the prevailing condition in the anodic compartment in an electrochemical membrane reactor (EMR). In the second part of this study, fresh as well as VPO catalyst already used in an EMR were characterised with XRD, XPS and temperature programmed oxidation (TPO). The XRD measurements revealed an unchanged bulk phase structure after operation in the EMR. Significant differences in the average oxidation states of vanadium in the catalyst layer in the EMR were determined via XPS, where the catalyst surface facing the electrolyte membrane was more oxidised than the surface facing the anodic gas compartment. The lowered uptake and release of oxygen was observed in TPO experiments for the catalyst used in the EMR.     

Benzene Formation During the Oxidation of Cyclohexene in the Presence and Absence of Thiophene over a Supported Palladium Catalyst

The catalytic oxidations of cyclohexene and thiophene, singly and together, have been studied over a Pd/CeO₂/Al₂O₃ monolith catalyst. On a freshly reduced sample, the oxidation of cyclohexene on its own commences below 100°C with benzene as the major product over a considerable temperature range, even when O₂ is in large excess. Benzene is still produced when cyclohexene and thiophene are co-oxidised and the reaction exhibits oscillations, associated with accumulation and removal of sulfur, at high conversions. The oxidation of thiophene is self-poisoned to some degree and sulfur accumulated during it considerably reduces the activity of the catalyst for the subsequent oxidation of cyclohexene. However, the maximum yield of benzene remains high.     

氨催化氧化催化剂Pt/CeO_2的制备及性能表征

二氧化铈具有紫外光吸收能力,以其为载体,通过光催化还原沉积可实现贵金属负载。本研究通过光催化还原沉积制备了氨氧化用Pt/CeO_2催化剂,利用X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDS)、透射电镜(TEM)、BET比表面积、电耦合高频等离子发射光谱(ICP)、X射线光电子能谱(XPS)、NH_3-程序升温脱附(NH_3-TPD)对样品的物理性质进行了表征,并在φ4 mm×2 mm石英反应管中对其氨催化氧化性能进行了评价。结果表明,该法制备的Pt/CeO_2催化剂活性组分铂含量仅为0.079 7%,在载体表面分散性好;在反应温度800℃,原料中O_2和NH_3比为15的条件下,氨转化率为100%,氮氧化合物收率可达80%。     

哌嗪合成中催化剂的研究

以Ｎ－β－羟乙基乙二胺为原料合成哌嗪，研制出一种高活性和选择性铜／载体型催化剂，并探讨了催化剂组成等因素对反应的影响，在Ｃｕ－Ｃｕ－Ｍｎ／γ－Ａｌ２Ｏ３催化剂和氢气的存在下，于１８０℃下反应２ｈ，原则料转化率达９８％以上，哌嗪收率为８８％。     

磷钒钼基多金属氧酸钯盐催化剂的合成与表征

以钯离子为抗衡离子,通过酸化-醚合法、置换法等,研究了磷钒钼基多金属氧酸钯盐催化剂的合成。采用红外吸收光谱技术对合成催化剂进行了表征。详述了试验方法与步骤,分析了试验影响因素。红外光谱研究表明该催化剂具有Keggin型结构,表明贵金属结合多金属氧酸盐的组合催化剂是可行的。     

An Overview of the Importance of Transition-Metal Nanoparticles in Cancer Research

Several authorities have implied that nanotechnology has a significant future in the development of advanced cancer therapies. Nanotechnology makes it possible to simultaneously administer drug combinations and engage the immune system to fight cancer. Nanoparticles can locate metastases in different organs and deliver medications to them. Using them allows for the effective reduction of tumors with minimal toxicity to healthy tissue. Transition-metal nanoparticles, through Fenton-type or Haber–Weiss-type reactions, generate reactive oxygen species. Through oxidative stress, the particles induce cell death via different pathways. The main limitation of the particles is their toxicity. Certain factors can control toxicity, such as route of administration, size, aggregation state, surface functionalization, or oxidation state. In this review, we attempt to discuss the effects and toxicity of transition-metal nanoparticles.     

高效使用甲醇转化催化剂的探讨

从催化剂的装填及催化剂的氧化还原等方面探讨了如何高效使用甲醇转化催化剂。     

The Activation of a Pd/γ-alumina Catalyst During Methane Combustion: Investigation of the Phenomenon and of Potential Causes

Activation phenomena of a Pd/γ-Al₂O₃ catalyst under methane combustion reaction conditions were studied. The activation of the catalyst with time-on-stream is not due to Cl removal from the surface but seems to be related to sintering of the palladium particles. This could induce structural changes in the palladium particle, which would favor the activation of O₂ on the surface of PdO.     

An Inexpensive and Efficient Copper Catalyst for N‐Arylation of Amines,Amides and Nitrogen‐Containing Heterocycles

An inexpensive and efficient catalyst system has been developed for the N‐arylation of nitrogen‐containing compounds including a variety of amines, amides, indole and imidazole. This simple protocol uses CuI as the catalyst, commercial available pipecolinic acid as the new ligand, K₂CO₃ as the base and DMF as the solvent.     

Development of a bath for codeposition of copper and platinum

To improve the mechanical properties of electrodeposited copper, a new bath was developed for the codeposition of copper and platinum. A pyrophosphate bath employing chloroplatinic acid as a source of platinum was investigated at current densities ranging from 1 to 4 A dm⁻² and temperatures from 20 to 60 °C. Bright, shiny and crack-free deposits were obtained at low current densities (i.e., 1–2 A dm⁻²). The amount of platinum observed in the deposits was found to increase with the current density and bath temperature. The Knoop hardness was found to increase with platinum content in the deposits. Corrosion rates measured in solutions of NaCl were found to decrease with platinum content. Deposits containing up to 3.9 wt % of platinum can be obtained by electrodeposition. As compared to electrodeposited copper from the acid bath, the Cu—Pt deposits exhibited a 17% increase in Knoop hardness and a 21% increase in corrosion resistance.     

Ionic Liquid as Catalyst and Reaction Medium: A Simple,Convenient and Green Procedure for the Synthesis of Thioethers,Thioesters and Dithianes using an Inexpensive Ionic Liquid, [pmIm]Br

An easily accessible and inexpensive room temperature ionic liquid, 1‐pentyl‐3‐methylimidazolium bromide, [pmIm]Br efficiently catalyzes the reaction of alkyl halides or acyl halides with thiols without any solvent at room temperature leading to the synthesis of thioethers and thioesters in high yields. This reaction has also been extended for the preparation of dithianes and transthioetherification. The ionic liquid is recovered and recycled for subsequent runs.     

氯化氢催化氧化制氯气催化剂的失活与再生

对浸渍法制备的Cu含量为8%的HCl催化氧化制Cl2催化剂的失活机理和再生方法进行了研究. 在温度400℃、压力0.12 MPa、摩尔比HCl/O2=1及HCl空速为0.8 h-1的条件下,在石英管固定床反应器中对催化剂进行了300 h的寿命评价. 结果表明,新鲜催化剂活性较好,HCl转化率在70%以上,而反应300 h后HCl转化率降到约50%. 催化剂活性下降的原因是CeO2晶粒聚并和活性组分流失. 较低温度下氯化可使失活催化剂再生,再生后催化剂可使HCl转化率恢复到70%以上.     

直接氧化甲苯或其一元取代物成醛进展

从电合成、气相氧化还原反应、液相氧化还原反应三方面小结了近年来直接氧化甲苯或其一元取代物成芳醛的研究状况,并简要介绍了其反应机理。     

Studies on the Synthesis and Activity of Three Tripalladium Complexes Containing Planaramine Ligands

The present study deals with the synthesis, characterization and activity against human cancer cell lines: A2780, A2780^cisR and A2780^ZD0473R of three tripalladium complexes, MH3, MH4 and MH5, that each have two planaramine ligands bound to the central metal ion. Cellular uptake levels, extent of DNA binding, and nature of interaction with salmon sperm and pBR322 plasmid DNA were determined for each complex. Palladium compounds are much more reactive than their corresponding platinum derivatives, which makes them therapeutically inactive but toxic. However, the results of the present study suggest that significant antitumour activity can be introduced in palladium complexes by lessening their reactivity by the introduction of sterically hindered ligands such as 2‐hydroxypyridine, 3‐hydroxypyridine and 4‐hydroxypyridine. When bound to the central palladium ion, 4‐hydroxypyridine appears to be more activating than 2‐hydroxypyridine and 3‐hydroxypyridine, suggesting that noncovalent interactions, such as hydrogen bonding, may also be key determinants of antitumour activity in addition to the steric effect. While cisplatin binds with DNA to form intrastrand GG adducts that causes local bending of a DNA strand, these planaramine‐derived palladium complexes are expected to bind with DNA and form a number of long‐range interstrand GG adducts that would cause a global change in DNA conformation, provided the tripalladium cations in MH3, MH4 and MH5 persist under physiological conditions.     

Effect of Microwave Radiation on the Synthesis of Ion Exchange Resins: A Comparative Study

A series of new ion exchange resins was synthesized in a microwave radiation field by modification of chloromethylated styrene/divinylbenzene (S/DVB) and vinylbenzylchloride/divinylbenzene (VBC/DVB) copolymers using amines. The modification processes have been executed simultaneously using the microwave-assisted method and the most efficient, conventional one. The greatest total sorption capacities for noble metals were achieved for two resins conventionally modified using ETDA ion exchange resins based on S/DVB matrices. The microwave-modified resins reveal only slightly lower and in some circumstances even better sorption capacity for noble metals than their conventionally-modified equivalents. The differences are discussed by effect of the synthesis method as evaluated using FTIR spectrophotometry.     

钯催化合成螺旋棒状聚合物

以1,4-双-（4’-溴苯酰基）苯和哌嗪为单体,三（二亚苄基丙酮）二钯为催化剂,1,1＇-联萘-2,2＇-二苯膦（BINAP）为配体,通过钯催化的胺基化反应缩聚合成了新型螺旋棒状结构聚合物。热分析结果表明,该聚合物具有良好的热稳定性（Ts=206℃,TD〉480℃）,