Cu(II)salen配合物催化三组分偶联反应合成炔丙胺(英文)

A one pot three‐component coupling reaction of phenylacetylene, aldehyde, and amine derivatives in the presence of Cu(II) Salen complex as an efficient heterogeneous catalyst under solvent‐free conditions is reported. The catalyst displayed high activity and afforded the corresponding propargylamines in good to excellent yields. This method provides a wide range of substrate applicability. The catalyst was reused several times without significant loss of its catalytic activity.     

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.     

Improved catalytic performance of Ni catalysts for steam methane reforming in a micro-channel reactor

Milliseconds process to produce hydrogen by steam methane reforming （SMR） reaction, based on Ni catalyst rather than noble catalyst such as Pd, Rh or Ru, in micro-channel reactors has been paid more and more attentions in recent years. This work aimed to further improve the catalytic performance of nickel-based catalyst by the introduction of additives, i.e., MgO and FeO, prepared by impregnation method on the micro-channels made of metal-ceramic complex substrate. The prepared catalysts were tested in the same micro-channel reactor by switching the catalyst plates. The results showed that among the tested catalysts Ni-Mg catalyst had the highest activity, especially under harsh conditions, i.e., at high space velocity and/or low reaction temperature. Moreover, the catalyst activity and selectivity were stable during the 12 h on stream test even when the ratio of steam to carbon （SIC） was as low as 1.0. The addition of MgO promoted the active Ni species to have a good dispersion on the substrate, leading to a better catalytic performance for SMR reaction.     

一氧化碳中选择氧化除氢催化剂的研究

Several supported Pd catalysts were prepared and their catalytic activity for selective oxidation of hydrogen was studied. The results show that the variety of the supports has great effect on the catalytic activity. The space velocity and the Pd loading show also certain influence. The most active catalyst Pd/C A can selectively remove H 2 at 170～200℃ and 1?800 h -1 from a feed gas consisting of H 2 (0 197%), O 2 (0 103%), CO (40%) and N 2 (balance). When CO content in the feed gas increases to 78%, the activity of the catalyst only decreases a little, indicating that the results obtained here seems applicable to the removal of H 2 from pure CO.     

Pd/Hβ-zeolite catalysts for catalytic combustion of toluene: Effect of SiO2/Al2O3 ratio

The effect of pure and high silica Hβ zeolites on the catalytic performance of toluene combustion over Pd/H/3 catalyst was evaluated.Pure and high silica β zeolites were prepared by direct synthesis procedures,then 0.1 wt% of palladium was impregnated on different Hβ zeolites via incipient wetness technique using palladium nitrate as the Pd source.The Pd/Hβ catalysts were characterized by XRD,N2 adsorption/desorption,H2O adsorption,NH3-TPD,H2-TPR and XPS techniques.With increasing the SIO2/Al2O3 ratio of β zeolite,the activity of the Pd/Hβ catalysts for toluene combustion increased clearly and the pure silica β zeolite supported Pd catalyst showed the best catalytic activity.The superior catalytic performance of Pd/β catalyst prepared from pure silica β zeolite was attributed to its high hydrophobicity and the preserving ability for PdO active species.     

Pd/Hβ-zeolite catalysts for catalytic combustion of toluene:Effect of SiO_2/Al_2O_3 ratio

The effect of pure and high silica Hβ zeolites on the catalytic performance of toluene combustion over Pd/Hβ catalyst was evaluated.Pure and high silica β zeolites were prepared by direct synthesis procedures,then 0.1 wt% of palladium was impregnated on different Hβ zeolites via in-cipient wetness technique using palladium nitrate as the Pd source.The Pd/Hβ catalysts were characterized by XRD,N2 adsorption/desorption,H2O adsorption,NH3-TPD,H2-TPR and XPS techniques.With increasing the SiO2/Al2O3 ratio of β zeolite,the activity of the Pd/Hβ catalysts for toluene combustion increased clearly and the pure silica β zeolite supported Pd catalyst showed the best catalytic activity.The superior catalytic performance of Pd/β catalyst prepared from pure silica β zeolite was attributed to its high hydrophobicity and the preserving ability for PdO active species.     

Ru effect on the catalytic performance of Pd@Ru/C catalysts for methanol electro-oxidation

Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation(MEO). The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry(CV) techniques. The results showed that the introduction of Ru element(2-10 wt%) into Pd 20 wt%/C(hereafter, denoted as Pd/C) produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C(hereafter, denoted as Pd@Ru5/C) catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E =-0.038 V(vs. Hg/HgO) was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of Jbp/Jfp(the ratio of MEO peak current density in the negative scan and positive scan) were also investigated. The result demonstrated that Pd@Ru5/C offering the smallest value of Jbp/Jfpdisplayed the best stable catalytic performance.     

Effect of Temperature on the Deactivation of a Pd-Fe／α-Al2O3 Catalyst for CO Coupling to Diethyl Oxalate

Destructive tests of the catalyst was carried out to study the effect of temperature on the catalytic activity of CO coupling to diethyl oxalate (DEO) over a Pd-Fe/Al2O3 catalyst. It was found that a temperature jump could cause the deactivation of the Pd-Fe/α-Al2O3 catalyst. The catalyst deactivated at different temperatures has different characteristics. After deactivation the crystal structure of α-Al2O3 did not change, but the Pd particle size was enlarged. Most of the Pd^0 were oxidized to Pd^2 . and Fe^2 was oxidized to Fe^3 on the surface of the deactivated catalyst. The catalyst could be regenerated, but its original activity could not be recovered completely.     

可磁性回收纳米级负载型杂多酸催化剂用于水中生物活性化合物的绿色合成(英文)

12‐Tungstophosphoric acid supported on aerosil silica and silica‐coated γ‐Fe2O3 nanoparticles was prepared and characterized using transmission electron microscopy,scanning electron microscopy,and inductively coupled plasma atomic emission spectroscopy.The catalytic activity of the two prepared catalysts was compared in the synthesis of 1,8‐dioxo‐9,10‐diaryldecahydroacridines in water.12‐Tungstophosphoric acid was highly dispersed on the silica‐coated γ‐Fe2O3 nanoparticles and showed higher activity and a higher reuse number compared with the acid supported on aerosil silica.The catalyst could be recovered simply by using an external magnetic field and could be reused several times without appreciable loss of its catalytic activity.     

N-Doped porous carbon supported palladium nanoparticles as a highly efficient and recyclable catalyst for the Suzuki coupling reaction

A new catalyst, Pd particles supported on the N-doped porous carbon(PC) derived from Zn-based metal–organic frameworks(zeolitic imidazolate framework: ZIF-8), was successfully prepared for the first time.The as-prepared catalyst was designated as N-doped PC-Pd, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscope, N_2 adsorption and inductively coupled plasma atomic emission spectroscopy. The N-doped PC-Pd composite exhibited high catalytic activity toward the Suzuki–Miyaura cross-coupling reactions. The yields of the products were in the range of 90%–99%. The catalyst could be readily recycled and reused at least 6 consecutive cycles without a significant loss of its catalytic activity.     

Preparation,characterization and application of silica‐supported palladium complex as a new and heterogeneous catalyst for Suzuki and Sonogashira reactions

An efficient heterogeneous Pd catalytic system has been developed, based on immobilization of Pd nanoparticles (PNPs) on a silica‐bonded propylamine–cyanuric–cysteine (SiO₂–pA–Cyan–Cys) substrate. The synthesized catalyst was characterized by transmission electron microscopy, scanning electron microscopy, FT‐IR, N₂ adsorption analysis (BET), TGA and inductively coupled plasma/atomic emission spectroscopy, and catalytic activity of this catalyst was investigated in the Suzuki and Sonogashira cross‐coupling reactions. The catalysts showed excellent performance in these two reactions, including various aryl halide derivatives (except aryl chloride derivatives) with phenylboronic acid and phenylacetylene under green conditions. Moreover, the catalyst was recycled for several runs without any significant loss of catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Recyclable N-heterocyclic carbene/palladium catalyst on graphene oxide for the aqueous-phase Suzuki reaction

Graphene oxide (GO) was functionalized with a N-heterocyclic carbene (NHC) precursor, 3-(3-aminopropyl)-1-methylimidazolium bromide ([APMIm][Br]) for the immobilization of palladium catalyst. The GO-supported NHC precursor (IMGO) formed a stable complex with Pd(OAc)₂ (GO–NHC–Pd), which showed excellent catalytic activity and fast reaction kinetics in the aqueous-phase Suzuki reaction of aryl bromides and chlorides at relatively mild conditions (1 h at 50 °C). The GO–NHC–Pd catalyst was reused several times without any loss of its catalytic activity in the Suzuki reaction of aryl bromide.     

Immobilized palladium nanoparticles on silica functionalized N-propylpiperazine sodium N-propionate (SBPPSP): catalytic activity evaluation in copper-free Sonogashira reaction

An efficient heterogeneous palladium catalyst system has been developed based on immobilization of Pd nanoparticles on silica-bonded N-propylpiperazine sodium N-propionate (SBPPSP) substrate. SBPPSP substrate can stabilize the Pd nanoparticles effectively so that it can improve their stability against aggregation. In addition, grafted piperazine species on to the silica backbone prevent the removing of Pd nanoparticles from the substrate surface. Transmission electron microscopy (TEM) of catalyst is shown the size of Pd nanoparticles, also it confirmed by particle size analyzer which shown the average size of 21 nm for Pd. The catalytic activity of these catalysts was investigated in the Sonogashira reaction. The catalyst could be recycled several times without appreciable loss in catalytic activity.     

Influence of the reaction parameters on the Pd—HCl catalysed synthesis of phenylacetic acid derivatives via reduction of mandelic acid derivatives with carbon monoxide

The catalytic system Pd/C—HCl is highly active in the reduction of mandelic acid derivatives to phenylacetic acid derivatives with carbon monoxide when the aromatic ring is para-substituted with a hydroxy group. Typical reaction conditions are: 70–110 °C, 20–100 atm of carbon monoxide, benzene—ethanol as reaction medium, substrate/Pd=10²–10⁴/1, HCl/substrate=0.3–0.8/1. [Pd] = 10⁻² −10⁻⁴ M. When the catalytic system is used in combination with PPh₃ a slightly higher activity is observed. Comparable results are observed when using a Pd(II) catalyst precursor such as PdX₂, in combination with PPh₃, or PdX₂(PPh₃)₂ (XCl, AcO). When operating at 110 °C, decomposition to metallic palladium occurs. Pd(II) complexes with diphosphine ligands, such as diphenylphosphinemethane, -ethane, -propane or -butane, do not show any catalytic activity and are recovered unchanged. These observations suggest that Pd(0) complexes play a key role in the catalytic cycle. The proposed catalytic cycle proceeds as follows: the chloride ArCHClCOOR, formed in situ upon reaction of ArCHOHCOOR with hydrochloric acid, oxidatively adds to a Pd(0) species with formation of a catalytic intermediate having a Pd—[CH(Ar)COOR] moiety, which inserts a CO molecule, yielding an acyl intermediate of the type Pd—[COCH(Ar)COOR]. The nucleophilic attack of H₂O on the carbon atom of the carbonyl ligand gives back the Pd(0) complex to the catalytic cycle and yields a phenylmalonic acid derivative, which produces the final product, ArCH₂COOR, upon CO₂ evolution. Alternatively, protonolysis of the intermediate having a Pd—[CH(Ar)COOR] moiety yields directly the final product and a Pd(II) species, which is then reduced by CO to Pd(0). Moreover, no catalytic activity is observed when the Pd/C—HCl system is used in combination with any one of the above diphosphine ligands, probably because these ligands block the sites on the catalyst able to promote the catalytic cycle or because they prevent the reduction of Pd(II) to Pd(0). The influence of the following reaction parameters has been studied: concentration of HCl, PPh₃, palladium and substrate, pressure of carbon monoxide, the temperature, reaction time and solvent. The results are compared with those obtained in the carbonylation of aromatic aldehydes to phenylacetic acid derivatives catalyzed by the same system, for which it has been proposed that the catalysis occurs via carbonylation of the aldehyde to a mandelic acid derivative as an intermediate, which is further reduced with CO to yield the final product.     

Cu含量对Pd-Cu/铝土矿CO氧化催化剂结构和性能的影响

利用资源丰富的天然铝土矿经NaOH溶液水热处理后焙烧,获得比表面积达174 m²·g^-1铝土矿载体,制备了双金属Pd-Cu为活性组分的催化剂,金属Pd负载量为0.5%（质量百分数）,以CO氧化反应为探针反应,详细考察了Cu含量的变化对催化剂物化性能的影响。研究发现,Cu的引入有利于提高金属Pd的分散度,同时随着Cu含量的变化,金属Pd与Cu之间以及金属与铝土矿载体之间的相互作用随之改变。催化剂的CO氧化反应性能评价结果表明,Pd和Cu负载量分别为0.5%和4%的样品（PdCu₄/MB）催化反应性能最佳。结合表征结果认为,PdCu₄/MB的高活性归因于良好的Pd和Cu分散度,金属Pd、Cu以及金属与载体之间较强的相互作用。此外,CO-TPD表征结果说明较强的CO吸附能力和从载体中获取氧的能力也有利于提高PdCu₄/MB样品的CO氧化反应性能。     

Cu含量对Pd-Cu/铝土矿CO氧化催化剂结构和性能的影响

利用资源丰富的天然铝土矿经NaOH溶液水热处理后焙烧,获得比表面积达174 m²·g^-1铝土矿载体,制备了双金属Pd-Cu为活性组分的催化剂,金属Pd负载量为0.5%（质量百分数）,以CO氧化反应为探针反应,详细考察了Cu含量的变化对催化剂物化性能的影响。研究发现,Cu的引入有利于提高金属Pd的分散度,同时随着Cu含量的变化,金属Pd与Cu之间以及金属与铝土矿载体之间的相互作用随之改变。催化剂的CO氧化反应性能评价结果表明,Pd和Cu负载量分别为0.5%和4%的样品（PdCu₄/MB）催化反应性能最佳。结合表征结果认为,PdCu₄/MB的高活性归因于良好的Pd和Cu分散度,金属Pd、Cu以及金属与载体之间较强的相互作用。此外,CO-TPD表征结果说明较强的CO吸附能力和从载体中获取氧的能力也有利于提高PdCu₄/MB样品的CO氧化反应性能。     

Design of heterogeneous catalysts with artificially controllable functions using effects of acoustic wave excitation

The effects of surface acoustic waves (SAWs) and resonance oscillation (RO) of bulk acoustic waves on catalytic activity and selectivity were studied in an attempt to design a heterogeneous catalyst which has artificially controllable functions for chemical reactions. The propagation of Rayleigh SAW and shear horizontal leaky SAW through thin Pd catalyst films deposited on poled ferroelectric LiNbO₃ and LiTaO₃ crystals caused considerable activity increases in ethanol oxidation: the enhancement was much larger for the oxidized than the reduced Pd. Similar effects were observed for a Ni catalyst. The RO effects on catalyst activation for ethanol oxidation were associated with the polarized (positive and negative) surfaces and the vibration modes of the ferroelectric substrates. The thickness extension mode resonance oscillation (TERO) of z-cut LiNbO3 caused different changes in the activation energy and reaction order between the positive and negative plane of the LiNbO3 substrate. Different catalyst activation was induced between TERO and the radial extension mode resonance oscillation (RERO) of a Pb_0.95Sr_0.05Zr_0.53Ti0.47O₃ ferroelectric substrate. For ethanol decomposition on a Ag catalyst, the TERO of z-cut LiNbO₃ increased ethylene production without significant enhancement of acetaldehyde production, thus demonstrating that TERO has the ability to change the selectivity in the catalytic reaction. Large dynamic lattice displacement, surface potential changes, and work function shifts were observed with TERO. A mechanism of acoustic wave excitation effect on the catalyst activation is discussed.     

Electrodeposited PdNi2 alloy with novelly enhanced catalytic activity for electrooxidation of formic acid

Bimetallic palladium–nickel (PdNi₂) alloy catalyst has been prepared for the electrooxidation of formic acid through a simple electrodepositing approach. Scanning Electron Microscopy and X-ray Diffraction revealed that the particle morphology and the crystalline lattice of PdNi₂ alloy were highly different from those of Pd. Although the PdNi₂ catalyst had less noble Pd content, the cyclic voltammetry and chronoamperometry results clearly demonstrated that its catalytic activity was significantly higher than that of Pd. The novel enhancement of catalytic activity was mainly ascribed to the weak absorption strength of intermediates on Pd through the interaction between Pd and additive Ni, which facilitated the formic acid oxidation through direct pathway.     

Pd/Co双金属纳米颗粒的制备及催化制氢性能

采用聚乙烯吡咯烷酮(PVP)保护的化学共还原法制备了Pd/Co双金属纳米颗粒, 研究了PVP及还原剂(NaBH₄)的用量、金属盐浓度、金属比例等对Pd/Co双金属纳米颗粒催化NaBH₄制氢性能的影响. 透射电子显微镜(TEM)的结果表明, 所制备的Pd/Co双金属纳米颗粒的平均粒径在1.5-2.8 nm之间. Pd/Co双金属纳米颗粒(BNPs)的催化活性远高于Pd与Co单金属纳米颗粒的活性; 当Pd/Co的理论原子比为1/9时, 双金属纳米颗粒的催化活性最高可达15570 mol·mol^-1·h^-1 (文中纳米颗粒的催化活性均为每摩尔Pd的活性). 密度泛函理论(DFT)的计算结果表明, Pd原子与Co原子之间发生电荷转移, 使得Pd原子带负电而Co原子带正电, 荷电的Pd和Co原子进而成为催化反应的活性中心. 所制备的Pd/Co双金属纳米颗粒具有很好的催化耐久性, 即使重复使用5次后, 该催化剂仍具有较高的催化活性, 且使用后的纳米颗粒催化剂也没有出现团聚现象. 双金属纳米颗粒催化NaBH₄水解反应的活化能约为54 kJ·mol^-1.     

Pd nanoparticles supported on CeO2 as efficient catalyst for hydrogen generation from formaldehyde solution at room temperature

A facile and efficient method for facilitating hydrogen generation from formaldehyde aqueous solution was developed using Pd nanoparticles supported on CeO₂ (Pd/CeO₂) as the catalyst. The prepared Pd/CeO₂ catalyst exhibited 100% H₂ selectivity and excellent catalytic activity for formaldehyde dehydrogenation with the initial rate of 2089 ml min⁻¹ g_Pd⁻¹ at room temperature and atmospheric pressure without any extra additive. The prepared catalyst was stable and reusable, and its catalytic activity kept almost unchanged after it was reused for the fifth run. Therefore, it is considered that this Pd/CeO₂ based hydrogen generation system may serve as an alternative hydrogen supply candidate for practical application.