聚乙烯基胺包裹Fe3O4@SiO2磁性微球用于Knoevenagel缩合（英文）简

Polyvinyl amine coated Fe₃O₄@SiO₂ composite microspheres with a core-shell structure were prepared and employed as a magnetic catalyst for Knoevenagel condensation under mild conditions. The catalyst can be readily recovered using a magnet and reused several times without loss in activity or selectivity. The performance of the magnetic base catalyst was compared with that of polyvinyl amine functionalized mesoporous SBA-15, which showed that the magnetic nanoparticles gave improved reaction rate and yield.     

超声法制备Au/Fe3O4及其催化还原4-硝基苯酚性能

通过简易的超声法以及原位还原法成功制备出了负载型可再生Au/Fe₃O₄催化剂。利用3-氨丙基三乙氧基硅烷（APTES）作为有机桥键,将Au固定在Fe₃O₄的表面,得到单分散磁性Au/Fe₃O₄。Au⁰在氨基的作用下不会团聚,因此具有较高的催化活性及稳定性。XRD、HRTEM、EDS和XPS等测试结果表明Au/Fe₃O₄已被成功制备。将其用于催化还原4-硝基苯酚得到4-氨基苯酚,表现出较高的催化活性,速率常数可达0.225 6 min^-1。重复性实验表明该催化剂具有良好的稳定性,反应9个循环之后,催化还原反应的转化率仍可达到94%。     

超声法制备Au/Fe_3O_4及其催化还原4-硝基苯酚性能

通过简易的超声法以及原位还原法成功制备出了负载型可再生Au/Fe_3O_4催化剂。利用3-氨丙基三乙氧基硅烷(APTES)作为有机桥键,将Au固定在Fe_3O_4的表面,得到单分散磁性Au/Fe_3O_4。Au0在氨基的作用下不会团聚,因此具有较高的催化活性及稳定性。XRD、HRTEM、EDS和XPS等测试结果表明Au/Fe_3O_4已被成功制备。将其用于催化还原4-硝基苯酚得到4-氨基苯酚,表现出较高的催化活性,速率常数可达0.225 6 min~(-1)。重复性实验表明该催化剂具有良好的稳定性,反应9个循环之后,催化还原反应的转化率仍可达到94%。     

Effect of 3% Re2O7/60%Al2O3 - 40%SiO2 Catalyst Alkylation Time and Temperature Using Et4Pb on Methyl Erucate Conversion

A study of the alkylation of 3% Re₂O₇/60%Al₂O₃-40%SiO₂ catalyst using tetraethyllead (Et₄Pb)(TEL) shows that the reaction time and temperature affect the catalyst activity and selectivity in the methyl erucate metathesis reaction. This revised version was published online in June 2006 with corrections to the Cover Date.     

A simple conversion of azlactones into indenones via H3PW12O40/Al2O3 catalyzed intramolecular Friedel-Crafts reaction

A rapid and simple procedure for the synthesis of the indenone derivatives, N-(1-oxo-1H-inden-2-yl)benzamides, via intramolecular Friedel-Crafts (IFC) reaction of (Z)-4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) catalyzed by H₃PW₁₂O₄₀ supported on neutral alumina under microwave irradiation has been developed. The reaction is straightforward and allows easy isolation of the product. The catalyst could be re-used up to four times after simple filtration.     

空心结构磁性固体碱催化剂Fe3O4@LDO的制备与性能

基于水滑石类化合物的复合氧化物(LDO)是一类性能优异的固体碱催化剂,对其进行改性和功能化引起了越来越多的关注。本文将空心结构和Fe_3O_4引入到镁铝复合氧化物中,制备了一种空心结构磁性固体碱催化剂Fe_3O_4@LDO。这种空心结构磁性固体碱催化剂粒子具有以镁铝复合氧化物为壳层,空心Fe_3O_4为核的核壳结构。由于其独特的空心结构,Fe_3O_4@LDO粒子的悬浊液具有良好的稳定性,将其应用于催化Knoevenagel缩合反应,达到平衡后苯甲醛的转化率约为62%,显示出较好的催化性能。同时,Fe_3O_4@LDO粒子具有较强的磁性,非常方便分离与回收,是一种性能优良的磁性固体碱催化剂。     

Selective oxidation of octadecan-1-ol to octadecanoic acid over Co3O4/SiO2 catalysts

Factors (reaction temperature, reaction time, flow rate of oxygen, amount of catalyst, etc.) influencing the catalytic properties of Co₃O₄/SiO₂catalyst in the oxidation octadecan-1-ol to octadecanoic acid were investigated. The catalysts were characterized by means of XRD, FT-IR and N₂-adsorption. The experimental results indicate that under the optimal condition the selectivity to octadecanoic acid reached 97.5 % over 5 % Co₃O₄/SiO₂ catalyst.This revised version was published online in December 2005 with corrections to the Cover Date.     

中空管状g-C3N4/Ag3PO4复合催化剂的制备及其可见光催化性能

用化学沉淀法制备中空管状g-C₃N₄/Ag₃PO₄复合催化剂。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射光谱(UV-Vis DRS)和荧光光谱对其结构、形貌和光学性能进行了表征。结果表明：Ag₃PO₄纳米颗粒均匀地分散在中空管状g-C₃N₄表面,两者紧密结合形成异质结。研究复合催化剂在可见光照射下降解盐酸四环素(TC)的光催化活性。结果显示：复合催化剂在80 min内对TC的降解率为98%,其降解反应速率常数是纯相Ag₃PO₄的3倍。经过5次循环实验后复合催化剂对于TC的降解率仍保持87%,具有优良的循环稳定性。捕获实验表明空穴(h⁺)和超氧负离子(·O^-₂)是光催化反应过程中的主要活性物种。根据能带理论,提出了复合催化剂异质结的Z型光催化机理。     

磁性纳米Pd/Fe3O4催化剂的制备及其在Heck反应中的应用

通过使用聚乙烯吡咯烷酮作为稳定剂,合成了磁性Pd/Fe₃O₄纳米颗粒催化剂。对该催化剂进行粉末X射线衍射、透射电子显微镜、感应耦合等离子体和磁性表征。将Pd/Fe₃O₄催化剂用于Heck反应,检测其催化性能。测试结果表明Pd纳米颗粒负载在Fe₃O₄纳米颗粒上,而且催化剂的尺寸<20 nm,并在Heck反应中表现了极好的催化性能。此外,催化剂可以通过磁场回收利用, 且催化活性没有显著的降低。     

Deactivation and regeneration of the B2O3/TiO2-ZrO2 catalyst in the vapor phase Beckmann rearrangement of cyclohexanone oxime

The deactivation and regeneration of B₂O₃/TiO₂-ZrO₂ catalyst for the vapor phase Beckmann rearrangement of cyclohexanone oxime to -caprolactam were studied. The fresh, deactivated and regenerated catalysts were characterized by using adsorption of nitrogen, X-ray diffraction (XRD), thermogravimetry (TG) and NH₃-temperature-programmed desorption (NH₃-TPD) techniques. The crystal structure and pore size distribution of the catalyst were retained after reaction, but the number of acid sites decreased significantly. There was a relationship between the amount of coke deposited on the catalyst and the decline in catalytic activity. These results suggest that the coke deposition on the surface of catalyst is mainly responsible for the catalyst deactivation. The catalytic activity can be recovered completely after calcining the deactivated catalyst in air flow at 600 °C for 8 h.     

磁性Fe3O4/石墨烯Photo-Fenton催化剂的制备及其催化活性

采用共沉淀法制备磁性Fe3O4/GE(石墨烯)催化剂,实现Fe3O4纳米颗粒生长和氧化石墨烯还原同步进行,采用FTIR、XRD、TEM及低温氮吸附-脱附等对Fe3O4/GE纳米催化剂的物相、颗粒粒径及比表面积进行了表征。在H2O2存在条件下,以亚甲基蓝为目标降解物,考察了在模拟太阳光下Fe3O4/GE的催化活性,当氧化石墨烯与Fe3O4的质量比为1∶10时,经过2 h催化反应,在pH=6条件下,对亚甲基蓝的降解率达到98.7%,经过10次循环使用后对染料溶液的降解率仍保持在95.7%以上,明显优于纯的Fe3O4。     

Al含量对Pt-SO2-4 /ZrO2-Al2O3固体超强酸催化

通过向SO^2-₄ /ZrO₂催化剂中同时引入适量的Pt和Al₂O₃, 制备出了具有较高催化性能和稳定性的Pt-SO^2-₄ /ZrO₂-Al₂O₃型固体超强酸催化剂. 以正戊烷异构化反应为探针, 考察了Al含量对催化剂性能的影响; 并采用X射线衍射(XRD)、比表面积测定(BET)、红外(IR)光谱、程序升温还原(TPR)、热重-差热分析(TG-DTA)和氨-程序升温脱附(NH₃-TPD)手段对催化剂进行了表征. 结果表明, Al能够提高ZrO₂的晶化温度, 抑制硫的分解, 增加催化剂的比表面积, 增强硫氧键的结合, 提高催化剂的还原性能, 增加催化剂的酸强度和酸总量. 当Al₂O₃含量(质量分数, w)为5.0%时, Pt-SO^2-₄ /ZrO₂-Al₂O₃固体超强酸催化剂的催化活性最好, 在100 h内异戊烷收率可稳定在52.0%以上, 选择性在98.2%以上.     

Zr0.5Ti0.5O2的添加对超临界裂解RP-3催化剂性能的影响

采用共沉淀法制备了Zr_0.5Ti_0.5O₂载体材料,将其掺杂在CeO₂-Al₂O₃ (CA)基催化剂中, 并对其催化活性进行了超临界裂解测试, 采用全自动吸附仪、X射线衍射(XRD)、透射电镜(TEM)、程序升温脱附(TPD)等方法对催化剂进行了表征. 实验结果表明, 催化剂能够明显降低裂解反应的温度, 600 ℃ CA基催化剂产气率是热裂解的2.8倍, 掺杂Zr_0.5Ti_0.5O₂载体材料的CA基催化剂是热裂解的4.0倍, 650 ℃时, 掺杂Zr_0.5Ti_0.5O₂载体材料的CA基催化剂热沉提高了0.55 MJ·kg^-1. BET结果表明, 掺杂Zr_0.5Ti_0.5O₂载体后催化剂出现双孔结构, 部分小孔的出现使得乙烯的选择性提高; NH₃-TPD结果表明, 掺杂Zr_0.5Ti_0.5O₂载体材料后, 催化剂强酸位的酸量增加了4.0倍,催化剂表现出更强的表面酸性和更集中的强酸酸中心密度, 有利于裂解多产烯烃.     

Preparation, characterization and catalyst application of ternary interpenetrating networks of poly 4-methyl vinyl pyridinium hydroxide-SiO2-Al2O3

In this work, Al₂O₃ was mixed with SiO₂ and poly 4-vinylpyridine by the sol-gel method in order to make a composite which is used as a heterogeneous basic catalyst for Knoevenagel condensation reaction. The physical and chemical properties of the composite catalyst were investigated by XRD, FT-IR, TG, BET and SEM techniques. The catalytic performance of each material was determined for the Knoevenagel condensation reaction between carbonyl compound and malononitrile. The reactions were performed in solvent-free conditions and the product was obtained in high yield and purity after a simple work-up. The effects of the amount of catalyst, amount of monomer for the synthesis of composite and recyclability of the heterogeneous composite were investigated. The composite catalyst used for this synthetically useful transformation showed considerable level of reusability besides very good activity.     

Magnetically separable Fe3O4 nanoparticles: an efficient catalyst for the synthesis of propargylamines

Magnetically separable Fe₃O₄ nanoparticles endow with an efficient and economic route for the synthesis of propargylamines by the three-component coupling of aldehyde, amine, and alkyne through C-H activation. The reaction is especially effective for reactions involving aliphatic aldehydes and no additional co-catalyst or activator is required. High catalytic activity and ease of recovery using an external magnetic field are additional eco-friendly attributes of this catalytic system. The catalyst was recycled for five times without a significant loss of catalytic activity.     

复合催化剂上CO2加氢合成C2烃类

介绍了由CO₂+H₂合成C2⁺烃的几种复合催化剂体系的研究进展，比较和评价了复合催化剂体系的活性和选择性及对C2⁺烃类生成的影响。着重于复合催化剂体系对C4⁺烃的生成及产物分布的影响并简述反应机理。     

V2O5/C catalyst for liquid phase oxidation of glyoxal to glyoxylic acid

A study of the catalytic activity of V₂O₅/C catalyst for the oxygen oxidation of glyoxal has been made, showing that glyoxylic acid can be formed without control of pH value and there is little oxalic acid from the excessive oxidation of glyoxylic acid. The studies of XRD and TEM have shown that V₂O₅ diffraction peaks gradually strengthen with the increase of the content of V₂O₅. With the content of 3% V₂O₅ and the calcination temperature of 573 K, V₂O₅/C catalyst displayed the best activity and selectivity. The conversion of glyoxal and the selectivity of glyoxylic acid reached 18.76% and 77.70% after 5 h, respectively. Moreover, V₂O₅/C catalyst showed small deactivation after recycling three times, which indicates that V₂O₅/C has a higher stability than noble metal catalysts in the reaction medium. Supported by the Technology Research and Development Project for University of Shanxi Province of China (Grant No. 20051272)     

An efficient synthesis of 5-substituted 1H-tetrazoles via B(C6F5)3 catalyzed [3+2] cycloaddition of nitriles and sodium azide

A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazole derivatives from various nitriles and sodium azide (NaN₃) via [3+2] cycloaddition reaction using B(C₆F₅)₃ as a catalyst. The present synthetic method displayed significant advantages such as low catalyst loading, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups.     

Ferric sulfate [Fe2(SO4)3·xH2O]: an efficient heterogeneous catalyst for the synthesis of tetrahydroquinoline derivatives using Povarov reaction

Fe₂(SO₄)₃·xH₂O can be used as an efficient and reusable catalyst for the synthesis of pyrano- and furanotetrahydroquinolines via one-pot three-component Povarov reaction involving aromatic aldehydes, aromatic amines, and cyclic enol ethers. The catalyst is recyclable, economically viable, and environmentally benign. This protocol provides good yields and diastereoselectivity as well as applicability on a wide range of substrates.     

Hydrothermal synthesis and magnetic properties of RMn2O5 (R=La, Pr, Nd, Tb, Bi) and LaMn2O5+δ

RMn₂O₅ (R=La, Pr, Nd, Tb, Bi) crystallites were prepared by a mild hydrothermal method and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and magnetic measurement. The formation of manganates was sensitive to the alkalinities and Mn-containing precursors of the reaction mixtures. This family of manganates is isostructural and has a space group of Pbam. The magnetic measurements for RMn₂O₅ showed an antiferromagnetic transition. The strong irreversibility between the ZFC and FC curves indicated a helicoidally magnetic structure below 40 K. The max d.c. susceptibilities of LaMn₂O_5+δ (δ=0.01, 0.06, 0.08, 0.16, 0.17) were found to be variable and the excess oxygen (δ) in the compounds was influenced by the alkalinity used in the hydrothermal synthesis.