镍(II)配合物官能化的MCM-41催化分子氧环氧化苯乙烯

制备了镍(II)席夫碱配合物官能化的MCM-41多相催化剂MCM-41-Ni.利用X射线粉末衍射、氮气物理吸附脱附、红外光谱、热重、电感耦合等离子体原子发射光谱、元素分析和透射电镜等方法对催化剂进行了表征.以氧气为氧化剂,MCM-41-Ni在催化环氧化苯乙烯的反应中表现出较高的催化活性;苯乙烯的转化率为95.2%,环氧苯乙烷的选择性为66.7%.系统地研究了反应温度、催化剂用量、溶剂以及反应时间对反应性能的影响.催化剂经过4次循环仍然表现出较好的稳定性和催化活性.     

Synthesis of 2,3-dihydroquinazolin-4(1<Emphasis Type="Italic">H</Emphasis>)-ones,disulfides and sulfoxides catalyzed by a zinc complex immobilized onto functionalized mesoporous MCM-41 as a mild and efficient catalyst

Zinc complex with 2-amino-3-hydroxy-pyridine ligand was immobilized onto chloropropyl-modified mesoporous silica MCM-41 (CP-MCM-41) via post-grafting method. The prepared catalyst has been characterized by low-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectrum, atomic adsorption spectroscopy and thermogravimetric analysis. The immobilized nano-structured material showed very good catalytic activity and excellent recycling efficiencies for the oxidation reaction of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides in the presence of aqueous hydrogen peroxide as oxidant at room temperature and the synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives in water.     

Synthesis and characterization of VO–vanillin complex immobilized on MCM-41 and its facile catalytic application in the sulfoxidation reaction,and synthesis of 2,3-dihydroquinazolin-4(1H)-ones and disulfides in green media

In this work, a vanillin complex is immobilized onto MCM-41 and characterized by FT-IR, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, and BET techniques. This supported Schiff base complex was found to be an efficient and recoverable catalyst for the chemoselective oxidation of sulfides into sulfoxides and thiols into their corresponding disulfides (using hydrogen peroxide as a green oxidant) and also a suitable catalyst for the preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives in water at 90°C. Using this protocol, we show that a variety of disulfides, sulfoxides, and 2,3-dihydroquinazolin-4(1H)-one derivatives can be synthesized in green conditions. The catalyst can be recovered and recycled for further reactions without appreciable loss of catalytic performance.     

介孔分子筛MCM-41固载多氮杂环席夫碱与偏钒酸钠共催化氧化苯一步制备苯酚

2-苯基-1,2,3-三唑醛和喹喔啉醛通过亚胺键固载到介孔分子筛MCM-41上,得到6种MCM-41固载多氮杂环席夫碱(L1~L6),用FT-IR、XRD和SEM等技术手段对所制得的固载席夫碱进行表征。 研究了以MCM-41固载多氮杂环席夫碱和金属盐偏钒酸钠为共同催化剂,过氧化氢为氧源,直接催化氧化苯合成苯酚,用气相色谱快速检测苯酚产率。 系统地考察了配体、金属盐、温度、溶剂、催化剂用量、反应时间、氧化剂等因素对反应的影响,产率最佳可达23.9%,选择性大于90%。 对催化剂扩大5倍量进行试验,得到23%的产率和93%的选择性,并且催化剂重复使用3次仍能达到19%的产率和90%以上的选择性。     

Synthesis and catalytic performance of MCM-41 modified with tetracarboxylphthalocyanine

A series of tetracarboxylphthalocyanines (MPc(COOH)₄, M = H, Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II)) were anchored onto MCM-41 by the following procedures: functionalization of MCM-41 with (EtO)₃SiCH₂CH₂CH₂NH₂ reacting with surface Si-OH, and anchoring MPc(COOH)₄ onto MCM-41 with a substitution reaction between chloroformyl and amino groups. The samples were characterized by infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, N₂ adsorption-desorption, and X-ray photoelectron spectroscopy. Catalytic activity of oxidation was tested using solutions of ethanethiol in petroleum ether and thiophene in octane; CoPc-CONH-MCM-41 displayed the highest conversion ratio of 90.15 % and 93.79 %, respectively.     

Ni-guanidine@MCM-41 NPs: a new catalyst for the synthesis of 4,4ʹ-(arylmethylene)-bis-(3-methyl-1-phenyl-1H-pyrazol-5-ols) and symmetric di-aryl sulfides

In this work, the surface of mesoporous MCM-41 was modified with guanidine, and then, Nickel particles have become immobilized on its surface (Ni-guanidine@MCM-41NPs). This heterogeneous catalyst has been identified by various techniques including: low-angle X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma, thermal gravimetric analysis and N₂ adsorption–desorption measurement isotherms, and its catalytic application was studied in the synthesis of 4,4ʹ-(arylmethylene)-bis-(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives and symmetric di-aryl sulfides. The prepared organometallic complex could be isolated, post-reaction, by simple filtration for several consecutive cycles without a notable change in its catalytic activity.

     

Iron oxide/MCM-41 mesoporous nanocomposites and their magnetorheology

Mesoporous nanocomposite materials of magnetic iron oxide-containing MCM-41 (IO/MCM-41) were prepared by simple thermal oxidation of Fe-containing MCM-41 initially prepared by a direct synthesis route using Fe³⁺ salt. The magnetic saturation of the fabricated nanocomposite materials was measured using a vibrating sample magnetometer, while surface morphology and inner framework of the composite materials were studied using a field emission scanning electron microscope and a transmission electron microscope to confirm their mesoporous nanocomposite formation. The fabricated magnetic materials were then adopted as a magnetorheological (MR) fluid, where the IO/MCM-41 magnetic nanocomposites were dispersed in a nonmagnetic medium oil in addition to as an additive for carbonyl iron-based MR fluid. Their MR properties of flow curve along with yield stress and viscoelastic properties under applied magnetic fields were investigated using a rotational rheometer.     

Tethering of nickel(II) Schiff-base complex onto mesoporous silica: An efficient heterogeneous catalyst for epoxidation of olefins

A new hybrid catalyst has been prepared by tethering a nickel(II) Schiff-base complex via post-synthesis modification of mesoporous silica, MCM-41. The Schiff-base has been derived from salicylaldehyde and 3-aminopropyltriethoxysilane (3-APTES) which is chemically anchored on MCM-41 via silicon alkoxide route. The anchored Schiff-bases imposed a stable planar coordination geometry around the central nickel ions. The catalyst has been characterized by elemental analysis, FT-IR, UV-Vis, small angle X-ray diffraction (SAX) and transmission electron microscopy (TEM) studies. The SAX and TEM measurement showed the mesoporosity of the catalyst. The activity of the catalyst has been assessed in the epoxidation of olefins using tert-butyl-hydroperoxide (tert-BuOOH) as oxidant in heterogeneous condition. Immobilized nickel catalyst was found to be catalytically more active and selective compared to the similar type of nickel(II) complex as well as Ni(NO₃)₂·6H₂O in homogeneous media. The catalyst can be recycled and reused several times without significant loss of activity.     

基于MCM-41模板制备β-MnO_2纳米纤维及其催化降解亚甲基蓝染料

以介孔氧化硅材料MCM-41为模板,硝酸锰为锰源,通过浸渍、450℃焙烧4 h得到Mn-MCM-41,用NaOH溶液溶解除去氧化硅模板得到锰氧化物,采用XRD,HRTEM和N2吸附-脱附等测试技术对产物进行了表征.结果表明,所得产物是纯相的β-MnO2纳米纤维,直径小于3 nm.纳米纤维之间有序排列组成类似MCM-41模板的介孔结构,其比表面积达到136.5 m2/g.将所制备的β-MnO2纳米纤维用于催化过氧化氢氧化分解质量浓度为60 mg/L的亚甲基蓝(MB)模拟染料废水,经100 min反应后,亚甲基蓝水溶液脱色率达到97.59%.所制备的催化剂对降解处理高浓度亚甲基蓝溶液,具有降解脱色率高和反应速度快等优点.     

An efficient green catalyst comprising 12-tungstophosphoric acid and MCM-41: synthesis characterization and diesterification of succinic acid,a potential bio-platform molecule

An efficient green catalyst comprising 12-tungstophosphoric acid (TPA) and MCM-41 was synthesized. The catalytic activity was evaluated for liquid phase solvent free diesterification of succinic acid. The support and the synthesized catalyst were characterized by various physico-chemical techniques. Fourier transform infrared, diffuse reflectance spectroscopy, and ³¹P NMR spectra indicate that the Keggin structure of TPA was not destroyed after anchoring to MCM-41. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy show that TPA is uniformly dispersed inside the channels without disturbing the hexagonal array of MCM-41. The present contribution reports solvent free diesterification of succinic acid with alcohols under mild reaction conditions. The catalyst shows higher activity toward diester, especially for dioctyl succinate 99% yield was obtained with very high turnover number, 12.43×10⁴. Also the catalyst shows potential of being used as recyclable catalytic material after simple regeneration without loss of any catalytic activity.     

Catalytic activity of Mn(III) porphyrins supported onto graphene oxide nano-sheets for green oxidation of sulfides

Abstract

In this research, oxidation of various sulfides with urea hydrogen peroxide (UHP) in the presence of manganese porphyrin grafted onto graphene oxide ([Mn(THPP)OAc@GO]) in ethanol was studied. The heterogenized catalyst was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR), and UV–Vis spectroscopy. The amount of Mn-porphyrin loaded on the GO nano-sheets was determined by atomic absorption spectroscopy (AAS) and the thermal stability of the heterogenized catalyst was investigated by thermo-gravimetric analysis (TGA). [Mn(THPP)OAc@GO] was applied for the green oxidation of different sulfides and the solid catalyst can be simply reused several times without losing its catalytic efficiency.     

Catalytic activity of nanosized Co-Cu oxide systems in the deep oxidation of methane

The effect of the composition of nanosized catalysts, produced by thermal decomposition of Co(II) and Cu(II) formates deposited on ZrO₂, SBA-15, and MCM-41, on their activity in the deep oxidation of methane was investigated. It was shown that the activity of the catalyst depends on the nature of the support and on the Co/Cu ratio. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 41, No. 6, pp. 331–335, November–December, 2005.     

Characterization of methylated nanoscale MCM-41 material

In this study, nanoscale MCM-41 molecular sieve was prepared under a basic condition by a hydrothermal method using cetyltrimethylammonium bromide as a template and tetraethyl orthosilicate as a silica source. Methylated nanoscale MCM-41 molecular sieve was prepared from the nanoscale MCM-41 by post-synthesis method using trimethylchlorosilane (TMCS) as coupling agent. The product was characterized by means of element analysis, powder X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, scanning electron microscopic (SEM), thermogravimetry-differential thermal analysis (TG-DTA). Powder XRD showed that the framework of the molecular sieve was well retained and the degree of ordering of the methylated MCM-41 decreases. IR spectra and the low-temperature nitrogen adsorption-desorption technique suggested that methyl was successfully grafted to the inner surface of the methylated MCM-41 and the mesoporous channels of the methylated MCM-41 were still maintained. Scanning electron microscopic results showed that the average size of the methylated MCM-41 prepared was 112 nm. Differential thermal analysis showed that the prepared material has preferable thermal stability and the methylated MCM-41 can be stable at 903 °C.     

Bi-MCM-41催化对氯甲苯选择氧化

合成了一系列Bi掺杂的MCM-41介孔分子筛,运用电感耦合等离子体原子光谱,X射线衍射,N2吸附脱附,透射电镜和紫外可见光谱对其进行了表征,并将其用于以H2O2为氧化剂,乙腈为溶剂的对氯甲苯选择氧化反应中.结果表明,Bi-MCM-41即便在底物量较大时也表现出较高的催化活性.浓缩反应液的检测结果表明,Bi在反应过程中无明显流失,同时该催化剂具有良好的循环使用性能.     

可重复使用的新型催化剂的合成、表征及在绿色条件下催化Suzuki和Heck反应:锚合在磁性纳米多孔的MCM-41上Pd(0)希夫碱络合物

将Pd希夫碱络合物固定在磁性的MCM-41表面上,做为环境友好且可循环使用的新型多相纳米催化剂,并采用红外光谱、振动探针式磁强计、能量散射谱、透射电镜、扫描电镜、热重、电感耦合等离子体发射光谱和X-射线衍射等对其进行了全面的表征.然后将该催化剂用于以PEG为绿色溶剂的一步法Suzuki和Heck合成反应中,均以较高收率得到目标产物.该法主要优点为反应时间短、反应条件绿色友好、操作简便、无需使用有毒的有机溶剂、催化剂使用量低,且底物适用性广.更为重要的是,通过外部磁场即可方便地将催化剂从反应混合物中分离出来,可重复使用数次而活性和稳定性未见明显下降.     

Anchoring of Cu(II)–vanillin Schiff base complex on MCM‐41: A highly efficient and recyclable catalyst for synthesis of sulfides and 5‐substituted 1H–tetrazoles and oxidation of sulfides to sulfoxides

A copper(II)–vanillin complex was immobilized onto MCM‐41 nanostructure and was used as an inexpensive, non‐toxic and heterogeneous catalyst in the synthesis of symmetric aryl sulfides by the cross‐coupling of aromatic halides with S₈ as an effective sulfur source, in the oxidation of sulfides to sulfoxides using 30% H₂O₂ as a green oxidant and in the synthesis of 5‐substituted 1H –tetrazoles from a smooth (3 + 2) cycloaddition of organic nitriles with sodium azide (NaN₃). The products were obtained in good to excellent yields. This catalyst could be reused several times without loss of activity. Characterization of the catalyst was performed using Fourier transform infrared, energy‐dispersive X‐ray and atomic absorption spectroscopies, X‐ray diffraction, thermogravimetric analysis, and scanning and transmission electron microscopies.     

Olefin epoxidation with tert-BuOOH catalyzed by vanadium polyoxometalate immobilized on ionic liquid-modified MCM-41

Preparation and characterization of vanadium-containing polyphosphomolybdates supported on ionic liquid-modified MCM-41, MCM-41-Im, are reported. The catalyst, [PVMo@MCM-41-Im], was characterized by elemental analysis, X-ray diffraction, scanning electron microscopy and also FT-IR, and UV-Vis spectroscopic methods. This heterogeneous catalytic system was applied for efficient epoxidation of various olefins in the presence of tert-BuOOH in 1,2-dichloroethane under reflux. The catalyst can be reused several times without apparent loss of its catalytic performance.     

Effect of the catalyst MCM-41 on the kinetic of the thermal decomposition of poly(ethylene terephthalate)

The aim of this work is to determine the activation energy for the thermal decomposition of poly(ethylene terephthalate)—PET, in the presence of a MCM-41 mesoporous catalyst. This material was synthesized by the hydrothermal method, using cetyltrimethylammonium as template. The PET sample has been submitted to thermal degradation alone and in presence of MCM-41 catalyst at a concentration of 25% in mass (MCM-41/PET). The degradation process was evaluated by thermogravimetry, at temperature range from 350 to 500 °C, under nitrogen atmosphere, with heating rates of 5, 10 and 25 °C min^?1. From TG, the activation energy, determined using the Flynn–Wall kinetic method, decreased from 231 kJ mol^?1, for the pure polymer (PET), to 195 kJ mol^?1, in the presence of the material (MCM-41/PET), showing the catalyst efficiency for the polymer decomposition process.     

Cu(II)–Schiff base complex‐functionalized magnetic Fe3O4 nanoparticles: a heterogeneous catalyst for various oxidation reactions

Cu(II)–Schiff base complex‐functionalized magnetic Fe₃O₄ nanoparticles were prepared and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy techniques. This compound acts as a highly active and selective catalyst for the oxidation of sulfides and thiols. These reactions can be carried out in ethanol or solvent‐free conditions in the presence of hydrogen peroxide with complete selectivity and very high conversion under mild reaction conditions. The designed catalytic system prevents effectively the over‐oxidation of sulfides to sulfones. Separation and recycling can also be easily done using a simple magnetic separation process. Copyright © 2015 John Wiley & Sons, Ltd.     

WO3 nanoparticles on MCM-48 as a highly selective and versatile heterogeneous catalyst for the oxidation of olefins, sulfides, and cyclic ketones

[reaction: see text] It is shown that nanosized WO(3) particles supported on MCM-48 work as a highly efficient and selective heterogeneous catalyst for the oxidation of olefins, sulfides, and cyclic ketones using hydrogen peroxide or peracetic acid. The catalytic activity of the supported tungstate was dependent on the nature of the supporting materials and particle size. The catalyst system employs environmentally benign oxidants in halide-free solvents, and it does not require phase-transfer agents and pH control.