采用燃烧技术制备CuO纳米粒子:一种高效且环境友好的用于芳族醛合成芳族腈催化剂(英文)

CuO nanoparticles were synthesized using an energy-efficient and rapid solution combustion technique with malic acid employed as a fuel. The combustion-derived CuO nanoparticles were used as catalysts in a one-pot synthesis of aromatic nitriles from aromatic aldehydes and hydroxylamine hydrochloride. The catalyst was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, and Brunauer-Emmett-Teller surface area analysis. The catalytic activity of the CuO nanoparticles in the synthesis of aromatic nitriles from aromatic aldehydes was evaluated. The present protocol offers the advantages of a clean reaction, simple methodology, short reaction duration (1-2 min), and high yield (85%-98%). The catalytic activity of the CuO nanoparticles was found to be higher than that of bulk CuO powder under the same conditions. The catalyst can also be recovered and reused up to four times with no significant loss of catalytic activity. The present approach is inexpensive and is a convenient technique suitable for industrial production of CuO nanoparticles and nitriles.     

用于甲烷水蒸气重整的镍基催化剂的失活和再生

The deactivation of nickel catalysts used in Arak and Razi petrochemical complexes followed by catalyst regeneration was evalu-ated. The characterization of the different structures was made by powder X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),transmission electron microscopy(TEM),and carbon & sulfur analyzer. The Ni particle size was estimated from XRD patterns and TEM graphs. The agglomeration of nickel particle and the poison by sulfur components were recognized as the main reasons in deactivation of Arak and Razi catalysts,respectively. The activity of the used catalysts before and after regeneration was measured on methane steam reforming at a CH4:H2O ratio of 1:3 at 850 oC. The regeneration processes for Arak and Razi samples were performed with CO2 as an oxidative atmosphere and steam as a regenerating agent,respectively. The results show that,(1) no residual sulfur components were on the regenerated Razi catalyst surface without changing the structure of the catalyst and the regenerated catalyst has gained 80% of its catalytic activity,and that(2) the nickel particle size of regenerated Arak specimen decreased remarkably as measured by Debye-Scherrer equation from XRD patterns. TEM images were in agreement with the XRD results and indicated a decrease in nickel particle size of regenerated catalyst. Additionally,in both regenerated catalysts all the coke on the surface of the support was eliminated after regeneration.     

Triton X-100辅助合成多级孔道结构ZSM-5沸石催化剂(英文)

ZSM-5 zeolite with a hexagonal cubic morphology was synthesized by a hydrothermal method using Triton X-100, a nonionic surfactant. The samples prepared with and without the surfactant were characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy, N2 adsorption, high resolution transmission electron microscopy(TEM), high resolution scanning electron mi-croscopy, energy dispersive X-ray analysis, and NH3 temperature-programmed desorption. The XRD patterns confirmed the formation of a pure ZSM-5 crystalline phase without secondary phases. TEM images revealed that the hexagonal cubes were made of peanut-shaped nanoparticles with voids.The catalytic activity of the zeolite samples was evaluated using the selective oxidation of benzyl alcohol with tertiary-butyl hydrogen peroxide as the oxidant at 90 °C. The surfactant-assisted prep-aration yielded a zeolite that gave a higher conversion than the one prepared in the absence of the surfactant. The catalyst was retrieved and reused four times without significant loss in activity and selectivity.     

Triton X-100辅助合成多级孔道结构ZSM-5沸石催化剂(英文)

ZSM-5 zeolite with a hexagonal cubic morphology was synthesized by a hydrothermal method using Triton X-100, a nonionic surfactant. The samples prepared with and without the surfactant were characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy, N2 adsorption, high resolution transmission electron microscopy(TEM), high resolution scanning electron mi-croscopy, energy dispersive X-ray analysis, and NH3 temperature-programmed desorption. The XRD patterns confirmed the formation of a pure ZSM-5 crystalline phase without secondary phases. TEM images revealed that the hexagonal cubes were made of peanut-shaped nanoparticles with voids.The catalytic activity of the zeolite samples was evaluated using the selective oxidation of benzyl alcohol with tertiary-butyl hydrogen peroxide as the oxidant at 90 °C. The surfactant-assisted prep-aration yielded a zeolite that gave a higher conversion than the one prepared in the absence of the surfactant. The catalyst was retrieved and reused four times without significant loss in activity and selectivity.     

Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.     

无溶剂条件下铜磷酸锆催化醇类和酚类化合物乙酰化(英文)

Copper zirconium phosphate nanoparticles have been used as an efficient catalyst for the acetyla-tion of a wide range of alcohols and phenols with acetic anhydride in good to excellent yields under solvent-free conditions. The steric and electronic properties of the different substrates had a signif-icant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively-coupled plasma optical emission spectroscopy,energy dispersive spectroscopy, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. These analyses revealed that the interlayer distance in the catalyst increased from 7.5 to 8.0  when Cu2+ was intercalated between the layers, whereas the crystallinity of the material was reduced. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity. This new method for the acetylation of alcohols and phenols has several key advantages, including mild and environmentally friendly reaction conditions, as well as good to excellent yields and a facile work-up.     

三(羟甲基)氨基甲烷改性SiO_2固载钯纳米粒子:合成、表征及其催化Heck偶联反应活性（英文）

The preparation of supported Pd nanoparticles on Tris(tris(hydroxymethyl)aminomethane)‐ modi‐fied Si O2 gel and their catalytic application in Heck coupling are investigated. The catalyst was char‐acterized using a combination of X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, and scanning electron microscopy/energy‐dispersive X‐ray spec‐troscopy. The supported Pd nanoparticles were found to be a highly active and reusable catalyst for the Heck reaction at a low Pd loading(0.02 mol%) because of stabilization by the Tris moieties. Several reaction parameters, including the type and amount of solvent, base, and temperature, were evaluated. The heterogeneity of the catalytic system was investigated using different approaches, and showed that slight Pd leaching into the reaction solution occurred under the reaction condi‐tions. Despite this metal leaching, the catalyst can be reused seven times without significant loss of its activity.     

二氧化硅包覆NiFe_2O_4担载Preyssler杂多酸用于合成双(二氢嘧啶酮)苯和3,4-二氢嘧啶-2(1H)-酮（英文）

A novel magnetic acidic catalyst comprising Preyssler(H14[Na P5W30O110]) heteropoly acid support‐ed on silica coated nickel ferrite nanoparticles (Ni Fe2O4@Si O2) was prepared.The catalyst was characterized by Fourier transform infrared,scanning electron microscopy,transmission electron microscopy,X‐ray diffraction,energy dispersive spectrum,VSM and particle size neasurement.Its catalytic activity was investigated for the synthesis of bis(dihydropyrimidinone)benzene and 3,4‐dihydropyrimidin‐2(1H)‐ones derivatives by the Biginelli reaction.With the catalyst,the reac‐tions occurred in less than 1 h with good to excellent yields.More importantly,the catalyst was easily separated from the reaction mixture by an external magnet and reused at least five times without degradation in the activity.     

Palladium particles from oxime-derived palladacycle supported on Fe3O4/oleic acid as a catalyst forthe copper-free Sonogashira cross-coupling reaction

An oxime-derived palladacycle was synthesized using4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an efficient catalyst for the copper-free Sonogashira cross-coupling reaction of various aryl halides with phenylacetylene in air and in ethanol or mixed aqueous medium. The oxime-derived palladacycle gave highly active palladium nanoparticles for the organicsynthesis. The coupling products were obtained in high yields with low Pd loading and theheterogeneous catalyst can be separated by an external magnet andreused six times without loss of its activity. The characterization of the catalyst wascarried out by XRD, SEM and TEM. Both TEM and XRD revealed that the palladium nanoparticles were well dispersed with diameters from 5 to 10 nm and average size 9.97 nm.     

源自水稻壳的高比表面纳米二氧化硅负载12-磷钨酸:一种高效纳米催化剂用于几种有机反应(英文)

Nano silica was prepared from rice husk with high surface area.X-ray diffraction(XRD) pattern showed that the amorphous form of silica was produced.Chemical composition of the nano silica was estimated by X-ray fluorescence spectroscopy and CHN analysis.The nano silica was used as a support for H3PW12O40.The nano silica and nano silica supported H3PW12O40 were characterized by inductively coupled plasma,XRD,transmission electron microscopy(TEM),N2 adsorption-desorption,and Fourier transform infrared spectroscopy.TEM images of nano silica as well as the supported catalyst displayed average size of 6 and 7 nm,respectively.The catalyst showed excellent activity in some important organic reactions including Biginelli,Hantzsch,Mannich,and Claisen-Schmidt reactions with good reusability.Catalytic activity of this nano catalyst is an improvement over the commercially available silica that is used to support H3PW12O40.     

树枝状钯纳米结构的控制合成及硝基苯加氢反应的催化活性

以氯钯酸为前驱体, 苯甲醇为还原剂和溶剂, 十六烷基吡咯烷酮(PVP)为稳定剂, 在微波辐射下制备了分散均匀、形貌均一的树枝状钯纳米结构. 产物用透射电子显微镜(TEM), X射线粉末衍射(XRD), X射线光电子能谱(XPS)进行了表征, 表明所制备的Pd纳米颗粒呈树枝状, 形貌单一, 分散均匀, 是由许多近似圆形的小颗粒自组装而成的二级结构. 对树枝状钯催化硝基苯加氢反应进行探究, 表明树枝状钯的催化活性比市售的钯碳催化剂的催化活性高.     

金属有机骨架材料MIL-53(Al)负载纳米Pd颗粒：一种CO氧化的活性催化剂

通过等体积浸渍法制备了金属有机骨架材料MIL-53(Al) (MIL：Materials of Institut Lavoisier)负载纳米Pd催化剂. 采用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对催化剂的结构进行了表征. 催化剂在反应前后XRD衍射峰保持不变,说明载体MIL-53(Al)具有良好的稳定性. 采用TEM对催化剂进行表征,结果表明,MIL-53(Al)的多孔晶体结构有助于形成高度分散的纳米Pd颗粒,样品2.7% (w) Pd/MIL-53 中Pd颗粒的平均粒径为2.21 nm. 该催化剂在CO氧化反应中表现出较高的催化活性,115 ℃达到完全转化. 同时催化剂可循环使用,多次反应后催化活性和催化剂结构都保持稳定.     

Pd/SWNTs负载型催化剂的制备及其催化性能

利用单壁碳纳米管(SWNTs)自身的还原性, 将PdCl2溶液中的Pd2+直接还原成金属Pd负载在SWNTs表面上, 制备了具有良好催化性能的Pd/SWNTs负载型催化剂. 通过透射电镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和热重分析(TG)对Pd/SWNTs 进行了表征, 并利用Suzuki反应对Pd/SWNTs的催化性能进行了测试. 实验结果表明, 用SWNTs与12 mmol·L-1的PdCl2的水溶液直接作用, 得到Pd/SWNTs催化材料的Pd负载量达到14.13%(w, 质量分数), 颗粒分散均匀, 粒径小(2 nm左右), 与SWNTs结合紧密; 用经过H2还原的Pd/SWNTs作催化剂, 在90 ℃下进行Suzuki反应, 30 min后反应就基本完成, 其联苯的产率达到98.10%, 催化活性较高, 可望广泛用于有机合成反应.     

中空介孔三氧化钨微球载钯催化剂的甲酸氧化电催化性能

采用喷雾干燥法和焙烧处理制备中空介孔三氧化钨微球(HMTTS),在其表面进一步负载活性成分Pd,得到纳米Pd/HMTTS复合催化剂. 采用X射线粉末衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等对催化剂的形貌和晶型结构进行了表征. 结果表明,Pd纳米粒子为面心立方晶体结构,均匀地分布在HMTTS表面. 采用循环伏安和计时电流法研究了在酸性溶液中Pd/HMTTS 催化剂对甲酸的电催化氧化性能,结果表明Pd/HMTTS 催化剂比普通的三氧化钨载钯催化剂(Pd/WO₃)对甲酸呈现出更高的电催化氧化活性和稳定性.HMTTS独特的中空介孔结构和表面特性以及氢溢流效应有利于甲酸在钯表面的直接脱氢氧化过程的发生.     

New bis(N‐heterocyclic carbene) palladium complex immobilized on magnetic nanoparticles: as a magnetic reusable catalyst in Suzuki‐Miyaura cross coupling reaction

A new bis(N ‐heterocyclic carbene) (NHC) palladium complex supported on silica coated magnetic nanoparticles (MNPs) was prepared using the reaction of synthesized Pd‐NHC complex with MNPs. The Pd‐NHC complex was prepared using the reaction of a hydroxyl‐functionalized bis‐imidazolium ionic liquid. The Pd‐NHC organometallic complex was used as a heterogeneous recyclable and active catalyst in the Suzuki‐Miyaura reaction and various aryl halides were coupled with arylboronic acids in order to synthesize diverse biaryls in good to excellent yields. The prepared catalyst was characterized by use of some different microscopic and spectroscopic techniques including elemental analysis, FT‐IR spectroscopy, diffuse reflectance UV–Vis spectrophotometery, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and X‐ray diffraction (XRD). The Pd‐NHC catalyst system is a magnetic reusable catalyst and it can be separated from the reaction mixture using an external magnetic field. The catalyst was reusable in the Suzuki‐Miyaura coupling reaction at least for 6 times without significant decreasing in its catalytic activity.     

Immobilized Pd on a NHC functionalized metal–organic framework MIL-101(Cr): an efficient heterogeneous catalyst in Suzuki−Miyaura coupling reaction in water

A novel Pd−NHC functionalized metal–organic framework (MOF) based on MIL-101(Cr) was synthesized and used as an efficient heterogeneous catalyst in the C-C bond formation reactions. Using this heterogeneous Pd catalyst system, the Suzuki−Miyaura coupling reaction was accomplished well in water, and coupling products were obtained in good to excellent yields in short reaction time. The Pd−NHC−MIL-101(Cr) was characterized using some different techniques, including Fourier transform-infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, inductively coupled plasma and elemental analysis. The microscopic techniques showed the discrete octahedron structure of MIL-101(Cr), which is also stable after chemical modification process to prepare the catalyst system. The TEM images of the catalyst showed the existence of palladium nanoparticles immobilized in the structure of the catalyst, while no reducing agent was used. It seems that the NHC groups and imidazolium moieties in the structure of the MOF can reduce Pd (II) to Pd (0) species. This modified MOF substrate can also prevent aggregation of Pd nanoparticles, resulting in high stability of them in organic transformation. The Pd−NHC−MIL-101(Cr) catalyst system could be simply extracted from the reaction mixture, providing an efficient synthetic method for the synthesis of biaryls derivatives using the aforementioned coupling reaction. The Pd−NHC−MIL-101(Cr) catalyst could be recycled in this organic reaction with almost consistent catalytic efficiency.     

超支化聚合物氮修饰Pd催化剂促进甲酸电催化氧化

通过原位聚合法制备了以超支化聚合物的氮修饰的PdN_x/C催化剂, 并考察了其催化甲酸电氧化反应的性能. 采用透射电子显微镜(TEM)、 X射线光电子能谱(XPS)和X射线衍射(XRD)等技术研究了氮的引入对催化活性组分Pd的形貌及表面电子形态的影响. 结果表明, 修饰氮后Pd纳米粒子粒径可稳定在2 nm, 并且保持了较高的分散度, 改善了表面Pd电子状态. 与Pd/C催化剂相比, 氮修饰的PdN₂₀/C用于甲酸电氧化的Pd单位质量比活性提高了10.9%.     

Synthesis of highly dispersed Pd/C electro-catalyst with high activity for formic acid oxidation

In this study, we present a simple process to obtain highly dispersed palladium nanoparticles on Vulcan XC-72R carbon support without any protective agent. To obtain high metal loading Pd/C catalyst without any surfactant, we modified the polyol process by employing NH₃ species as a mediation to control the reaction pathway to avoid the precipitation of Pd(OH)₂, and hence the agglomeration of Pd nanoparticles. The obtained Pd/C sample was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. The results show that highly dispersed Pd/C catalyst with an average diameter of 3.0 nm could be obtained in this novel process. The activity of formic acid oxidation on this Pd/C catalyst was examined via cyclic voltammetry technique and it is found that the catalytic activity is greatly enhanced due to the reduced particle size and the improved dispersion of palladium nanoparticles on the carbon surface.     

Palladium nanoparticles supported on poly (N-vinylpyrrolidone)-grafted silica as new recyclable catalyst for Heck cross-coupling reactions

Novel catalytic system based on palladium nanoparticles supported on poly (N-vinylpyrrolidone) (PVP) grafted silica was prepared. Aminopropylsilica was reacted with acryloyl chloride to form acrylamidopropylsilica, and onto this functionalized silica vinylpyrrolidone monomer was polymerized by free-radical polymerization. The complexation of PVP-grafted silica with PdCl₂ was carried out to obtain the heterogeneous catalytic system. X-ray diffraction (XRD) technique and transmission electron microscopy (TEM) image showed that palladium dispersed through the support in nanometer size. This catalytic system exhibited excellent activity in cross-coupling reactions of aryl iodides, bromides and also chlorides with olefinic compounds in Heck-Mizoraki reactions in short reaction time and high yields. Elemental analysis of Pd by inductively coupled plasma (ICP) technique and hot filtration test showed low leaching of the metal into solution from the supported catalyst. The catalyst can be reused several times in repeating Heck reaction cycles without considerable loss in its activity.     

Novel marine-based gold nanocatalyst in solvent-free synthesis of polyhydroquinoline derivatives: Green and sustainable protocol

We report an ecofriendly synthetic approach for the fabrication of biogenic gold nanoparticles (AuNPs) using electron-rich sea cucumber extract as a bio-reductant and stabilizing agent in reducing gold cations into AuNPs at the optimal conditions. The produced AuNPs are spherical in shape with an average particle size of 11 ± 1.5 nm in transmission electron microscopy (TEM) and exhibited a crystal structure of face-centered cubic in X-ray diffraction (XRD) analyses. Our results indicated that bioinspired AuNPs demonstrate superior catalytic activity in the safe and facile one-pot synthesis of polyhydroquinoline derivatives under solvent-free reaction conditions. This green route encompasses multiple benefits including highly recyclable bioinspired catalyst (5 cycles), short reaction times, convenient workout, high to excellent product yields (82%–97%), and nonhazardous conditions.