“原位”红外光谱追踪反应条件下催化体系的变化

为了观察和监测反应条件下中间产物和催化剂的变化,自行设计并安装了高温高压红外流动池。池体用不锈钢制成,窗口材料为NaCl或CaF₂。它可承受100atm和200℃。整个测量系统包括高压釜、循环泵、红外池等。用Microlab-600型红外分光光度计记录图谱。池内温度和压力与反应釜桐同,可对反应液体、气体或气液混合物进行"原位"追踪。当用铑膦络合物催化剂进行丙烯氢甲酰化反应时,在近于工业反应条件下(t=10O℃,P=17atm,正丁醛溶剂),检测到催化剂母体Rh(acac)(CO)(PPh₃)转化为活性物种RhH(CO)₂(PPh₃)₂;在合成气压力较低时,只转化为RhH(CO)(PPh₃)₃;此活性物种随催化剂失活而消失。催化剂加氧失活后,检测到配位体三苯基膦氧化为氧化三苯基膦,催化剂生成二聚物,丙烯氧化成丙酮,追踪到原料气CO氧化为CO₃的动态过程。本文对"原位"红外光谱实验方法、高温高压红外池作了介绍,并给出有关实验数据和结果。     

MIL-101(Fe)高效催化 β-蒎烯与甲醛的Prins缩合制备诺卜醇

通过水热晶化法制备了MIL-101(Fe)金属有机骨架材料, 利用X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR)、 热重分析(TG)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和X射线光电子能谱(XPS)对催化剂的结构和形貌进行了表征. 结果表明, 该材料用于催化β-蒎烯与甲醛的Prins缩合制备诺卜醇反应的效果优异; 催化剂合成温度、 合成时间、 催化剂用量、 反应溶剂、 反应温度和反应时间对β-蒎烯的反应结果均有一定影响. 在相似的反应条件下, 合成的MIL-101(Fe)催化β-蒎烯制备诺卜醇反应的最佳条件为使用150 ℃下反应15 h合成的催化剂MIL-101(Fe), 在90 ℃下反应8 h得到的β-蒎烯转化率高达97.3%, 诺卜醇选择性达到96.7%.     

超顺磁性介孔纳米颗粒嫁接肟Pd环络合物对Heck反应的催化活性

采用溶胶-凝胶法制备出介孔二氧化硅包裹四氧化三铁纳米复合颗粒,在其表面修饰巯基,并以此为载体通过-SCH2-化学键嫁接长链的肟钯环络合物.利用透射电镜(TEM)、高分辨透射电镜(HRTEM)、傅里叶变换红外(FT-IR)光谱、N2吸附-脱附、X光电子能谱(XPS)、振动样品磁强计(VSM)等手段对催化剂进行表征,通过Heck反应对催化剂的活性进行评价.实验结果表明:所制备的磁性颗粒直径约为150nm,比表面积为287.0m2·g-1,且具有大小为3.5nm呈不规则的孔道结构,整个催化剂呈现超顺磁性.对于碘代苯与丙烯酸乙酯之间的Heck反应,2.5h后碘代苯的转化率可达到99%,催化剂在重复使用6次后能保持很高的催化活性(碘代苯转化率为95%).催化剂可稳定分散于反应体系中,并可在外磁场作用下快速与反应体系分离.     

Ultra‐low‐loading palladium nanoparticles stabilized on nanocrystalline Polyaniline (Pd@PANI): A efficient,green, and recyclable catalyst for the reduction of nitroarenes

Ultra‐low‐loading Pd@PANI nanocomposites (0.048 w.t% Pd) were synthesized via a method that combined interfacial polymerization and in situ composite with camphor sulfonic acid ((+)‐CSA) as a dopant. Transmission electron microscopy (TEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and X‐ray photoelectron spectroscopy (XPS) were performed to characterize the structures. It can be used as an efficient catalyst for the reduction of nitroarenes in aqueous solution by using a smaller amount of NaBH₄ (2.5 equiv.) at room temperature with high activity (TON = 3.4 × 10³), good stability (cycled eight times), as well as wide applicability (27 substrates). The catalyst also showed a marvelous activity in the gram‐level reaction (yield = 92%). UV–Visible spectrophotometry was used to investigate the reaction kinetics for the reduction of 4‐nitrophenol to 4‐aminophenol, and the results reconfirmed the excellent performance of the catalyst. The unique properties and superior performance of the prepared ultra‐low‐loading Pd@PANI nanocomposites lead it be an attractive alternative catalyst for conventional organic catalytic applications.     

CoMoO_4晶须材料的制备及烯烃环氧化催化性能研究

利用Co(CH_3COO)_2、氧化钼、钼酸和咪唑为基础原料,在水热条件下成功制备了CoMoO_4晶须材料.通过元素分析、X-射线衍射、傅里叶变换红外光谱以及扫描电子显微镜等手段对材料的结构和形态进行了表征,证明为完整均匀的CoMoO_4晶须.在环辛烯环氧化催化反应中对材料的催化性能进行了测试,结果证明CoMoO_4晶须具有优良的非均相催化性能.     

Titania-silica nanoparticles ensemblies assisted heterogeneous catalytic strategy for the synthesis of pharmacologically significant 2,3-diaryl-3,4-dihydroimidazo[4,5-b]indole scaffolds

Present paper elicits the multicomponent reaction (MCR) strategy assisted by titania nanoparticles hosted on silica (TiO₂.SiO₂ NPs) as heterogeneous catalyst to synthesize a series of pharmacologically significant 2,3-diaryl-3,4-dihydroimidazo[4,5-b]indole derivatives. To the best of our information, the use of isatin as one of the precursors was hitherto unreported. The decrease in reaction time, low catalyst loading, high product yield (up to 92%), and excellent reusability of the catalyst (up to 7 cycles) put this protocol under the umbrella of green chemistry tenets. Characterization of catalysts was achieved through a number of techniques viz., energy-dispersive X-ray (EDX) spectroscopy, field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD), fourier transform infrared (FTIR) spectra of adsorbed pyridine, temperature-programmed desorption of ammonia, and porosity measurements by nitrogen adsorption (Brunauer–Emmett–Teller [BET] method). Also, the structures of synthesized compounds were corroborated on the basis of FTIR, nuclear magnetic resonance (NMR), mass, and elemental analyses data.     

Functional mesoporous poly (ionic liquid) derived from P123: From synthesis to catalysis and alkylation of styrene and o‐xylene

A novel strategy was proposed for the fabrication of high‐performance acidic mesoporous poly ionic liquids catalyst. In this work, mesoporous poly ionic liquids (MPILs) were synthesized with P123 (PEO₂₀PPO₇₀PEO₂₀) served as pore‐forming agent. Then, MPILs were treated with PW^3? anion exchange, thereby fabricating PW/MPIL‐S(x). MPIL and PW/MPIL‐S(x) were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), Thermogravimetric analysis (TA), N₂ adsorption–desorption and Fourier transform infrared (FT‐IR) spectra and X‐ray photoelectron spectroscopy (XPS) spectra. The effect of solvent and concentration of P123 on the morphology and mesoporous structure of MPILs were investigated systematically. And the results show that MPILs were featured with mesoporous channel structure, high surface area (up to 737 m²/g) and large pore volumes (1.16 cm³/g), which benefit heterogeneous phase reaction (such as, alkylation of styrene with o‐xylene). In the alkylation reaction, under optimal reaction conditions, the catalyst PW/MPIL‐THF (4.0 g) shows high conversion of styrene (100%) and PXE yield (96.21%), demonstrating the excellent catalytic activities. Furthermore, PW/MPIL‐S(x) are easy to be separated from the catalytic system by filtration and show no obvious decrease in catalytic activity after 6 cycle runs. The obtained PW/MPIL‐S(x) catalyst exhibit high thermal and mechanical stability as well, indicating extensive application in high temperature acidic catalysis. This work might open up a new method for the synthesizing of porous polymer catalysts in the future.     

INVESTIGATION OF THE FRIEDEL-CRAFTS REACTION OF THE CHLOROMETHYLATED COPOLYMER OF STYRENE-DIVINYLBENZENE

In the presence of Friedel-Crafts catalyst, the chloromethylated copolymer of styrene-divinylben-zene may react with each other and cross-link by itself Thus a new type of polymeric adsorbent wasobtained, and its structure was identified by its physical properties and infrared spectra. The Friedel-Crafts reaction is manifestly affected by the nature of the solvent, the kind and amount of catalystused, reaction temperature and reaction time, etc. The porous structure and physical properties of the adsorbent prepared have been investigatedsystematically. The adsorbent has high specific surface area (1000--1300m~2/g), porosity, narrowpore distribution,high skeleton density and good mechanical properties.     

Synthesis and Characterization of Polymer Anchored Cu(Ⅱ) Complexes: Heterogeneous Catalysts for Preparation of Diaryl Ethers

Polymer anchored Cu(II) Schiff base complexes have been prepared and characterized by using scanning electron microscope (SEM), elemental analysis, atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), spectrometric methods like diffuse reflectance spectra of solid (DRS) and fourier transform infrared spectroscopy (FTIR). These catalysts show excellent catalytic activity in the O‐arylation reaction of aryl halides with phenol in acetonitrile using Cs₂CO₃ at 70°C under an open air condition to give diaryl ethers in high yields. The effects of various parameters such as solvent, catalyst from different copper salt and base on the reaction system have been studied. The reaction is applicable to a wide variety of substituted aryl halides and phenols with different steric and electronic properties. These catalysts are recovered by simple filtration and the reusability experiments show that these catalysts can be used five times without much loss in the catalytic activity.     

Catalytic performance of chitosan‐Schiff base supported Pd/Co bimetallic catalyst for acrylamide with phenyl halide

The chitosan‐Schiff base supported palladium and cobalt bimetallic complex was synthesized in a simple method and characterized by Fourier‐transform infrared spectroscopy (FT‐IR), powder X‐ray diffraction (XRD), and X‐ray photoelectron spectra (XPS). It was found that the catalyst has great activity and stability in the coupling of acrylamide (AA) with the phenyl halide. The influence of various bimetallic catalysts, the different molar ratio of Co/Pd, the bases, the amount of the catalyst and base, and the molar ratio of iodobenzene/AA on the reaction were investigated. The results showed that the catalytic activity of the molar ratio of Co/Pd (3/1) was the best when the iodobenzene was used as a substrate. The yield of the cinnamamide did not change significantly after ten runs. It has been revealed that the catalyst was efficient for the reaction. Copyright © 2009 John Wiley & Sons, Ltd.     

Co、Mo掺杂对Ni／ZnO—ZrO2催化剂催化噻吩加氢脱硫性能的影响

采用固相合成法制备了ZnO—ZrO2载体,并采用浸渍法制备了镍基催化剂,以噻吩加氢脱硫反应为探针考察了Co、Mo的掺杂对Ni／ZnO—ZrO2催化性能的影响．采用NH,吸附红外光谱（IR）、程序升温脱附（TPD）、程序升温还原（TPR）、X射线衍射（XRD）等技术对催化剂进行了表征．研究结果表明,ZnO－ZrO2复合载体对噻吩加氢脱硫反应有一定的活性,反应温度为400℃时噻吩转化率为6．4％;Co的加入提高了Ni／ZnO-ZrO2的催化活性,噻吩转化率可达97．3％;相反,Mo的掺杂则降低了Ni／ZnO—ZrO2的催化活性,噻吩转化率为65．0％．这是由于Co的掺杂使活性组分Ni分散度提高,氧化态的Ni变得容易还原,在同样的还原条件下催化剂表面有更多的活性中心;而Mo掺杂则使Ni／ZnO—ZrO2催化剂中氧化态的Ni变得难以还原,部分以NiO形式存在,活性中心数量减少．三种催化剂表面均存在L酸中心,Co掺杂使Ni／ZnO-ZrO2催化剂表面弱酸中心和中等强度酸中心的强度及数量均增大．No掺杂则减弱了催化剂表面弱酸中心和中强酸中心的强度．对其酸量则影响不大．     

改性三氧化二铬催化1,1,3,3-四氯丙烯氟化高选择性合成反式-1-氯-3,3,3-三氟丙烯研究

反式-1-氯-3, 3, 3-三氟丙烯 (HCFO-1233zd (E))是近年来正在研发的第四代发泡剂,其大气臭氧消耗潜能值为0.00024,温室效应潜能值为7.0,毒性低,常态下不燃,使用安全;它也是合成含氟精细化工品的中间体,以及合成氟树脂和氟弹性体的单体。本论文制备了Al,Zn,Co改性的Cr2O3催化剂,将其成功应用于1, 1, 3, 3-四氯丙烯（HCC-1230za）与氟化氢反应中,高选择性地合成HCFO-1233zd (E),复合催化剂Zn / Cr2O3显示高稳定性,其中HCC-1230za转化率高达99.4％,HCFO-1233zd（E）的选择性高达98.2％。反应条件诸如反应物HF / HCC-1230za 的摩尔比和反应温度等对产物分布有显着影响。在相对较低的温度（200?C）和较大的HF / HCC-1230za 摩尔比（10：1）下,对HCFO-1233zd（E）的选择性有利。通过XRD,XPS,BET和V70吡啶吸附红外光谱技术对复合催化剂Zn / Cr2O3进行了表征。 XRD结果表明,催化剂中大多数无定形Cr2O3和高度分散微晶相Cr2O3共同导致催化剂的高活性和高稳定性。HCC-1230za的转化率与预氟化处理催化剂Zn / Cr2O3的比表面积有关,催化剂的比表面积越高,催化活性越高。XPS光谱表明,在预氟化过程中,表面铬氧化物可能与F原子强烈相互作用,从而导致Cr原子的化学环境发生广泛变化。V70吡啶吸附红外光谱和氨-程序升温脱附技术结果证明尚未失活的催化剂Lewis 酸和Br?nsted酸中心的数目和强度与新制备的催化剂相比明显提高。     

Density functional theory (DFT) and DRIFTS investigations of the formation and adsorption of enolic species on the Ag/Al2O3 surface

Molecular structure and vibrational frequencies of the novel surface enolic species intermediate on Ag/Al2O3 have been investigated by means of density functional theory (DFT) calculations and in situ infrared spectroscopy. The geometrical structures and vibrational frequencies were obtained at the B3P86 levels of DFT and compared with the corresponding experimental values. Theoretical calculations show that the calculated IR spectra are in good agreement with the experimental spectroscopic results. In addition, the adsorption energy of enolic species on the Ag/Al2O3 catalyst surface was also evaluated. The reaction mechanism from C2H5OH to enolic species on Ag/Al2O3 catalyst was proposed.     

Solvent-free coupling of aldehyde,alkyne, and amine over a versatile catalyst: Ag-functionalized mesoporous S,P-doped g-C3N4

In the present study, we introduce mesoporous g-C₃N₄/Ag co-doped with P and S which was designed and acquired by using mesoporous silica (SBA-15) as a hard templating agent and thiourea and chitosan phosphate as the dopants. The prepared catalyst was completely identified by FT-IR (Fourier-transform infrared spectroscopy), XRD (X-ray powder diffraction), FE-SEM (field-emission scanning electron microscopy), EDX (energy-dispersive spectroscopy), TEM (transmission electron microscopy), and Raman spectroscopy. The efficiency of the synthesized catalyst was evaluated toward the three-component coupling reaction, frequently named as A3 coupling. The higher activity of the prepared catalyst is because of the synergistic effects of phosphorus and sulfur co-doped together with Ag deposition. The desired products were achieved by an environmentally safe catalyst under the optimized conditions in high yields and short reaction time ranges.

     

氯甲基化苯乙烯-二乙烯苯共聚体傅氏交联反应的研究

氯甲基化苯乙烯-二乙烯苯共聚体在傅氏催化剂的存在下可以发生自身的傅氏交联反应从而制得一类新型吸附树脂,它们的物理化学性质和红外光谱分析证实了这类吸附树脂的结构。溶剂的性质,催化剂的种类和用量、反应温度和时间都对反应有明显的影响。这类吸附树脂具有比表面积高(1000—1300m~2/g)、孔度较大、孔分布较窄、比重大和机械强度高等特点。     

Ni‐W Catalysts Supported on HZSM‐5/HMS for the Hydrogenation Reaction of Aromatic Compounds: Effect of Ni/W Ratio on Activity,Stability, and Kinetics

Ni‐W/HZSM5‐HMS catalysts were evaluated for the benzene hydrogenation reaction at 130–190°C. To study the catalyst characterization, X‐ray diffraction, X‐ray fluorescence, Fourier transform infrared, UV–vis, diffuse reflectance spectra, temperature‐programmed desorption of NH₃, FT‐IR of adsorbed pyridine measurements (Py‐IR), H₂ chemisorption, nitrogen adsorption–desorption, and TGA techniques were used. Kinetics of benzene hydrogenation was investigated under various hydrogen and benzene pressures, and the effect of reaction conditions on catalytic performance was studied. The results showed that bimetallic catalysts have better ability than a monometallic catalyst (Ni/HZSM5‐HMS) for this reaction, such as maximum benzene conversion (100%), minimum toluene conversion (1.76–40%), very low converted xylene, benzene selectivity (100%), good catalytic stability against coke deposition, and appropriate kinetic parameters.     

高分子钼铁硫原子簇催化剂的合成反应及其结构表征

以乙烯基吡啶的共聚物为高分子载体,用固相合成的方法,通过多步反应合成了一个高分子钼铁硫原子簇催化剂。用紫外可见光谱和红外光谱分析研究了该催化剂的结构,并说明它具有原子簇结构。本催化剂在KBH_4还原剂存在下,对乙炔加氢反应具有催化活性,可以循环使用。     

On the local sensitivity of different IR techniques: Ba species relevant in NO(x) storage-reduction

IR spectroscopy is widely used to elucidate reaction mechanisms in NO(x) storage and reduction (NSR). Observed band positions and assignments of vibrational modes, however, differ remarkably among the various investigations. We report an IR study of barium species relevant in NSR, aiming to clarify the source of the reported discrepancies and different surface and bulk sensitivity of various IR measurement configurations. Four IR techniques, namely, transmission IR spectroscopy (TIRS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), attenuated total reflection infrared spectroscopy (ATR-IRS), polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS), all suitable for in situ studies of the reaction system, were used. Depending on the IR technique certain bands undergo a clear band shift or disappearance, evidently showing different surface and bulk sensitivity. In spectra of barium nitrate recorded by the more bulk sensitive IR techniques, i.e. TIRS, ATR-IRS, and PM-IRRAS, fewer bands appeared than in the more surface sensitive DRIFTS spectra. This work constitutes a collection of IR spectra of reference barium compounds for the clarification of species present in the NSR catalyst system. The band position or the presence of certain bands assigned to the same chemical species may deviate if the spectra were measured by different IR techniques, especially if the compared IR techniques differ in surface/bulk sensitivity. This implies that the band assignment valid for spectra measured by DRIFTS can be transferred to TIRS, ATR-IRS, and PM-IRRAS only with precautions.     

Magnesium chloride supported high-mileage catalysts for olefin polymerization. IV. FTIR and quantitative analysis of modifiers in the catalysts

Fourier transform infrared (FTIR) spectra were obtained for a typical MgCl₂-supported, high-mileage catalyst for propylene polymerization. When ball-milling MgCl₂ with ethyl benzoate (EB), the latter is incorporated into the support (I) by Lewis acid-base complexation involving both oxygen atoms of the ester. Reaction of (I) with p-cresol (PC) resulted in a material (II) that contains all the characteristic IR bands of PC. The reaction of (II) that contains all the characteristic IR bands of PC. The reaction of (II) with AlEt₃ (TEA) resulted in (III) whose spectrum supports the reaction observed by product analysis and NMR spectroscopy. There was no evidence of any reaction between TEA and EB. Further reaction of (III) with an excess of TiCl₄ caused substantial removal of the p-cresol moiety as shown by the diminution of its characteristic bands. Finally, activation with 3TEA-1MT (methyl-p-toluate) complexes gave spectra that revealed the presence of MT in the activated catalyst without any visage of p-cresol moiety. The nondestructive FTIR method, however, is not quantitative. Quantitative analysis of the organic components in the support materials (I), (II), and (III) and the catalysts was accomplished by hydrolysis of the inorganic components, extraction with ether, and analysis by gas chromatography. The results are in good agreement with composition deducted from elemental analysis and substantiate the FTIR conclusions.     

PEG‐DIL‐based MnCl42−: A novel phase transfer catalyst for nucleophilic substitution reactions of benzyl halides

Poly(ethylene glycol) dicationic ionic liquid‐based MnCl₄^2? was prepared by nucleophilic substitution of poly(ethylene glycol) dichloride with methylimidazole followed by reaction with MnCl₂. The structural properties of the catalyst were systematically investigated using Fourier transform infrared, UV–visible and Raman spectra and thermogravimetric analysis. The application of this catalyst allows the synthesis of a variety of benzyl thiocyanates and azides in high yield under reflux conditions in water. The main advantages of this method are its easy nature, rapidity, environmental benignity and high yields.