Synthesis,Characterization, and Catalytic Activity of New Cu(II) Complexes of Schiff Base: Effective Catalysts for Decolorization of Acid Red 37 Dye Solution

In this paper, three new Cu(II) Schiff base complexes with three different anions (acetate, chloride, and nitrate) were successfully synthesized and characterized by elemental analysis, mass spectra, molar conductance, FT‐IR, NMR,UV–vis spectroscopy, magnetic moment, ESR, and thermal analysis. The catalytic performances of these complexes in decolorization of azo dye, Acid Red 37, were evaluated. Copper(II) complexes were found to be an efficient catalyst for decolorization of Acid Red 37 in the presence of hydrogen peroxide. The catalytic investigation revealed that the Cu(II) complex with acetate anion (complex 1 ) performed the highest catalytic activity. The kinetics of the decolorization of AR37 with this catalyst was studied, and the observed rate constant was determined. The effects of different reaction parameters such as catalyst dosage, solution pH, initial concentration of H₂O₂, dye solution, and reaction temperature on the reaction rate constant were studied. The best reacting conditions should be catalyst dosage = 0.004 g, initial pH 4.0, [H₂O₂]₀ = 0.8 M, and [AR37]₀ = 1.16 M at temperature 25°C. Under these conditions, about 99% of AR37 was decolorized within 60 min. The results indicated that the Cu(II) complex with the acetate anion is a promising catalyst for wastewater treatment.     

Synthesis,characterization, and catalytic activity of a polymer-supported copper(II) complex with a thiosemicarbazone ligand

A thiosemicarbazone Cu(II) complex anchored to a polystyrene framework has been synthesized and characterized by analytical and spectroscopic techniques. The complex was found to be a highly active catalyst for the oxidation of various organic substrates including alkenes and alcohols using H₂O₂ as oxidant. The reaction conditions were optimized with respect to temperature, solvent, oxidant, catalyst amount, and substrate to peroxide ratio. The heterogeneous catalyst was reused five times without significant loss of activity. A comparison between the catalytic activities of this polymer-supported Cu(II) complex and its homogeneous analogue was carried out.     

Pt-BaO催化剂的NOx储存-还原化学及结构-性能关系

NOx储存-还原(NSR)技术是目前稀燃汽车尾气中NOx消除的最有前景的催化技术之一,NSR催化过程中稀燃/富燃条件的交替运行、NSR催化剂上化学计量反应与催化反应的耦合赋予了NSR催化过程迥异于常规连续流动气固相催化反应的特点.本文首先介绍了目前人们对Pt-BaO催化剂上NSR基本化学过程的认识;在此基础上,结合本研...     

树枝状吡啶亚胺铬催化剂的合成及其催化性能研究

以1. 0代聚酰胺-胺树枝状大分子为配体骨架、吡啶二甲醛为原料,合成了一种新型树枝状吡啶亚胺(DPI)配体,再以CrCl_3·6H_2O为络合试剂,制备DPI-Cr催化剂。采用IR、UV-Vis、MS、元素分析等确证了产物结构。考察溶剂种类、助催化剂种类、反应温度、乙烯压力以及Al/Cr摩尔比对DPI-Cr催化乙烯齐聚性能的影响。结果表明,DPI-Cr催化剂表现出良好的催化活性和烯烃选择性,优化反应条件下,催化效率可达4. 91×10~4g/mol Cr·h,C_6和C_8选择性为73. 90%。     

酸性功能化离子液体催化合成叶青素

以含磺酸基离子液体1-(4-磺酸基)丁基-3-甲基咪唑四氟硼酸盐([4-sulfbmim][BF₄])为酸性催化剂,由乙缩醛和苯甲醇合成了叶青素。 采用正交实验方法考察了合成条件的影响,固定反应温度为20 ℃条件下,确定优化合成条件为：n(苯甲醇)∶n(乙缩醛)=1∶8,反应时间60 min,催化剂用量为每摩尔苯甲醇4 g,产率为92.2%。 与H₂SO₄催化剂相比[4-sulfbmim][BF₄]的催化活性相对较弱,但综合效果优于H₂SO₄。 [4-sulfbmim][BF₄]循环使用6次,催化活性基本不变。     

A Pyridinium-Pyridinium Zinc(II) Porphyrin Ion Porous Organic Polymer as Efficient Heterogeneous Catalyst for Cycloaddition of Epoxides with CO2

A zinc(II)porphyrin-based ion porous organic polymer (ZnTPyPBr₄-iPOP) is successfully synthesized from newly designed pyridinium-functionalized cationic Zn-porphyrin monomer (ZnTPyPBr₄) by free radical self-polymerization, and is employed as an efficient bifunctional heterogeneous catalyst for CO₂ cycloaddition reaction with epoxides. The ZnTPyPBr₄-iPOP exhibits excellent catalytic performance and good substrate expansion in CO₂ cycloaddition reaction under solvent-free and cocatalyst-free conditions with a TOF as high as 15,500 h⁻¹ for the cycloaddition of CO₂ and epichlorohydrin. The synergistic effect of zinc(II)porphyrin as the Lewis acidic site and the Br⁻ anion as the nucleophile in ZnTPyPBr₄-iPOP responds to the high catalytic activity. Moreover, ZnTPyPBr₄-iPOP can easily be recovered and reused at least seven times without the loss of activity. This work provides a valuable approach for the synthesis of novel and efficient heterogeneous catalyst for CO₂ cycloaddition.     

Low-Temperature Oxidation of Carbon Monoxide: The Synthesis and Properties of a Catalyst Based on Titanium Dioxide,Nanodiamond, and Palladium for CO Oxidation

A catalyst based on TiO₂ and nanodiamond with a 10 wt % palladium content of the catalyst was synthesized. The effect of the nanodiamond content on the catalytic properties in a reaction of CO oxidation at room temperature and low concentrations of CO (<100 mg/m³) was studied. It was established that, at a nanodiamond content of the catalyst from 7 to 9 wt % and a palladium content of 10 wt %, the rate of CO oxidation reached a maximum, and it was higher by a factor of 2.5 than the rate of CO oxidation on a catalyst based on pure TiO₂, which included palladium clusters. With the use of transmission electron microscopy, XRD X-ray diffractometry, and X-ray photoelectron spectroscopy, it was found that the clusters of palladium covered with palladium oxide with an average cluster size of 4 nm were formed on the surface of the TiO₂ carrier. It was assumed that the catalyst synthesized is promising for applications in catalytic and photocatalytic air-cleaning systems.     

Construction of a MOF-Supported Palladium Catalyst via Metal Metathesis

A new MOF-supported heterogeneous palladium catalyst Pd/NBB-1 has been synthesized successfully through the effective metal metathesis between Pd(CF₃COO)₂ and NBB-1. NBB-1 is a two-dimensional zinc metal-organic framework constructed from 2-aminoterephthalate (NH₂−H₂BDC) and 2,2′-bipyridine-5-carboxylate (HBPC) by solvothermal method. The replacement efficiency of Pd(II) to Zn(II) is up to 72% after only 24 hours, which is beneficial to the catalytic application. Pd/NBB-1 with a low loading of 2 mol% works efficiently in the 1,4-addition reaction of arylboronic acids with α,β-unsaturated ketones in air, and its catalytic activity keeps unchanged after 3 reaction cycles. This work provides a new strategy to effectively prepare supported noble metal/MOF catalysts, which would further increase the practical applications of metal-organic frameworks.     

Membrane-Supported Layered Coordination Polymer as an Advanced Sustainable Catalyst for Desulfurization

The application of a catalytic membrane in the oxidative desulfurization of a multicomponent model diesel formed by most refractory sulfur compounds present in fuel is reported here for the first time. The catalytic membrane was prepared by the impregnation of the active lamellar [Gd(H₄nmp)(H₂O)₂]Cl·2H₂O (UAV-59) coordination polymer (CP) into a polymethyl methacrylate (PMMA, acrylic glass) supporting membrane. The use of the catalytic membrane in the liquid–liquid system instead of a powder catalyst arises as an enormous advantage associated with the facility of catalyst handling while avoiding catalyst mass loss. The optimization of various parameters allowed to achieve a near complete desulfurization after 3 h under sustainable conditions, i.e., using an aqueous H₂O₂ as oxidant and an ionic liquid as extraction solvent ([BMIM]PF₆, 1:0.5 ratio diesel:[BMIM]PF₆). The performance of the catalytic membrane and of the powdered UAV-59 catalyst was comparable, with the advantage that the former could be recycled successfully for a higher number of desulfurization cycles without the need of washing and drying procedures between reaction cycles, turning the catalytic membrane process more cost-efficient and suitable for future industrial application.     

Aqueous-Phase Nitrile Hydration Catalyzed by an In Situ Generated Air-Stable Ruthenium Catalyst

RuCl₂(PTA)₄ (PTA=1,3,5-triaza-7-phosphaadamantane) is an active, recyclable, air-stable, aqueous-phase nitrile hydration catalyst. The development of an in situ generated aqueous-phase nitrile hydration catalyst (RuCl₃⋅3 H₂O+6 equivalents PTA) is reported. The activity of the in situ catalyst is comparable to RuCl₂(PTA)₄. The effects of [PTA] on the activity of the reaction were investigated: the catalytic activity, in general, increases as the pH goes up, which shows a positive correlation with [PTA]. The pH effects were further explored for both the in situ and RuCl₂(PTA)₄ catalyzed reaction in phosphate buffer solutions with particular attention given to pH 6.8 buffer. Increased catalytic activity was observed at pH 6.8 versus water for both systems with turnover frequency (TOF) up to 135 h⁻¹ observed for RuCl₂(PTA)₄ and 64 h⁻¹ for the in situ catalyst. Catalyst loading down to 0.001 mol % was examined with turnover numbers as high as 22 000 reported. Similar to the preformed catalyst, RuCl₂(PTA)₄, the in situ catalyst could be recycled more than five times without significant loss of activity from either water or pH 6.8 buffer.     

Synthesis and characterization of bis[2-(1H-benzimidazol-2-yl)benzoato]nickel(II), and its use for preparation of dimethyl carbonate from methanol and CO2

A new complex, bis[2-(1H-benzimidazol-2-yl)benzoato]nickel(II) (NiL₂), has been synthesized and characterized. It was used as catalyst for synthesis of dimethyl carbonate (DMC) from methanol and CO₂ in the presence of dicyclohexyl carbodiimide (DCC) as promoter. The effects of temperature, reaction time, and amount of catalyst on the reaction, and the reusability of the catalyst, were investigated. A catalytic mechanism is proposed. The results revealed that NiL₂ + DCC had excellent catalytic activity, because this catalytic system promoted facile formation of DMC, with acceptable yield, in the presence of a small amount of NiL₂ and under moderate conditions (80 °C, 1.0 MPa). Moreover, the catalyst has been consecutively used five times without significant loss of activity.     

Efficient and Reusable Sn(II)‐containing Imidazolium‐based Ionic Liquid as a Catalyst for the Oxidation of Benzyl Alcohol

A simple and efficient catalytic system [BBIM]Br–SnCl₂ for the oxidation of benzyl alcohol using hydrogen peroxide as the oxidant has been developed. Reaction conditions such as the catalyst dose, the solvents, reaction temperature, reaction time, and the amount of hydrogen peroxide were investigated. The optimum reaction conditions identified were 0.11 g of catalyst, no solvent, 65°C, 15 min, and 2 mmol of hydrogen peroxide. Oxidation of various alcohols was also investigated under the optimized conditions. The catalyst [BBIM]Br–SnCl₂ can be easily recovered and reused for six reaction runs without significant loss of catalytic activity, because the Sn species of the catalyst can be coordinated with the imidazole ring of the ionic liquid. The reused catalyst was further characterized by Fourier transform infrared spectroscopy to evaluate its chemical properties. The results proved that the [BBIM]Br–SnCl₂ catalyst was stable and reusable for the oxidation reactions. A possible mechanism for the oxidation of benzyl alcohol to benzaldehyde is proposed.     

1D Azido bridged Cu(II) coordination polymer with 1,3-oxazolidine ligand as an effective catalyst for green click synthesis of 1,2,3-triazoles

A new 1D azido bridged Cu(II) coordination polymer with 1,3-oxazolidine based ligand, [Cu(H₃L)(μ_1,3-N₃)(N₃)]_n ( 1 ), was synthesized and characterized by elemental analysis and spectroscopic methods. The structure of 1 was also determined by single crystal X-ray analysis which indicated the 1D polymeric chain is generated by end-to-end (EE) azide bridge. The obtained compound was employed as catalyst in green click synthesis of β-hydroxy-1,2,3-triazoles from one-pot three-component cycloaddition reaction of epoxide-azide-alkyne. The catalytic reactions were carried out in water as a safe, cheap and green solvent. The catalytic studies indicated that the obtained 1D azido bridged Cu(II) coordination polymer is an active catalyst for preparing β-hydroxy-1,2,3-triazoles. The effect of temperature on the selectivity of the catalytic system was studied and the results indicated this catalytic system has high selectivity at low temperatures. The structure the product obtained from the reaction of 2,3-epoxypropylphenylether, azide and 1-ethynyl-1-cyclohexanol ( T4 ) was determined by single crystal X-ray analysis. The results indicate Cu(II) coordination polymers can be a new class of catalytic systems for green click synthesis of 1,2,3-triazoles.     

Palladium as Catalyst in a Polycondensed Matrix, Part ii

In Part I of this series results on the formation of Pd-organic amine adducts, their polymerization, and the catalytic behavior of the catalyst formed were reported [1]. In the present paper results of IR and N₂ adsorption measurements are discussed. This includes the interactions of organic amines and Pd. Conclusions were drawn on the physical structure of the catalyst. Under the applied reaction conditions the Pd-containing polymers were formed to a certain extent, but in all cases a non-negligible part of the Pd-amine adduct remains unchanged.     

Liquid-phase catalytic oxidation of organic substrates by a recyclable polymer-supported copper(II) complex

Chloromethylated polystyrene beads cross-linked with 6.5 % divinylbenzene were functionalized with 2-(2′-pyridyl) benzimidazole (PBIMH) and on subsequent treatment with Cu(OAc)₂ in methanol gave a polymer-supported diacetatobis(2-pyridylbenzimidazole)copper(II) complex [PS-(PBIM)₂Cu(II)], which was characterized by physicochemical techniques. The supported complex showed excellent catalytic activity toward the oxidation of industrially important organic compounds such as phenol, benzyl alcohol, cyclohexanol, styrene, and ethylbenzene. An effective catalytic protocol was developed by varying reaction parameters such as the catalyst and substrate concentrations, reaction time, temperature, and substrate-to-oxidant ratio to obtain maximum selectivity with high yields of products. Possible reaction mechanisms were worked out. The catalyst could be recycled five times without any metal leaching or much loss in activity. This catalyst is truly heterogeneous and allows for easy work up, as well as recyclability and excellent product yields under mild conditions.     

Solvent-free,microwave-assisted highly efficient,rapid and simple synthesis of biphenyl compounds by using silica based Pd(II) catalyst

To maintain catalytic performance of any catalyst for a long time, the selection of support material is a very important parameter for heterogeneous catalytic systems, and this performance makes the catalyst valuable. In view of its low cost and availability, silica can be considered as a good support material for transition metal ions in the cross coupling reactions. Therefore, this study describes i) silica-gel based palladium catalyst with a long-term catalytic performance, ii) rapid, simple, economic, and green procedure which was developed for Suzuki reactions. The catalyst showed superior reusability (ten runs) and catalytic efficiency against coupling reactions under mild conditions (50°C, 5 min and air atmosphere). Moreover, the catalyst gave partially good reaction yields with aril chlorides which have poor activity in coupling reactions. In addition, an excellent turnover number (TON: 66000) and frequency (TOF: 825000) were obtained using very small catalyst loading (1.5 × 10^?3 mol %). This paper concludes that silica-gel based Pd(II) catalyst and the protocol of synthesis of biaryls were suitable for coupling reactions.     

Polystyrene‐Gallium Trichloride Complex: A Mild,Highly Efficient,and Recyclable Polymeric Lewis Acid Catalyst for Chemoselective Silylation of Alcohols and Phenols with Hexamethyldisilazane

Polystyrene‐supported gallium trichloride (PS/GaCl₃) as a highly active and reusable heterogeneous Lewis acid effectively activates hexamethyldisilazane (HMDS) for the efficient silylation of alcohols and phenols at room temperature. In this heterogeneous catalytic system, primary, secondary, and tertiary alcohols as well as phenols were converted to their corresponding trimethylsilyl ethers with short reaction times and high yields under mild reaction conditions. The heterogenized catalyst is of high reusability and stability in the silylation reactions and was recovered several times with negligible loss in its activity or a negligible catalyst leaching, and also there is no need for regeneration. It is noteworthy that this method can be used for chemoselective silylation of different alcohols and phenols with high yields.     

生物质炭基固体酸催化剂的制备

 以生物质木粉为原料, 采用炭化-磺化法制备了炭基固体酸催化剂, 并用于油酸与甲醇的酯化反应, 考察了制备条件对炭基固体酸催化剂活性的影响. 采用 X 射线衍射、红外光谱、热重分析、高分辨透射电子显微镜及元素分析等手段对催化剂进行了表征. 结果表明, 由生物质木粉制备的炭基固体酸催化剂具有较高催化酯化反应活性, 在 400 oC 下炭化 0.5 h, 135 oC 下磺化 1 h 制备的炭基固体酸催化剂在精馏分水连续酯化装置中催化油酸与甲醇的酯化反应 2 h 时, 酯化转化率达到 96%. 采用炭化-磺化法制备的生物质炭基固体酸催化剂具有蠕虫状的无序乱层炭结构, 磺酸基 (－SO3H) 含量高达 13.25%, 并且在 220 oC 以下时具有良好的热稳定性.     

KI与无机铵盐催化CO2与环氧丙烷合成碳酸丙烯酯

以无毒、合成简单、廉价的无机铵盐(氨基甲酸铵、碳酸氢铵、碳酸铵等)为助催化剂, 研究其对卤化钾(KCl、KBr、KI)催化CO₂与环氧丙烷合成碳酸丙烯酯(PC)的影响. 结果表明, 卤化钾与无机铵盐显示出很好的协同催化效应. 其中以氨基甲酸铵为助催化剂, KI为主催化剂时, 催化合成PC的效果最好. 同时考察了催化剂用量、反应温度、CO₂初始压力、PC的预加入量、反应时间等因素对反应的影响. 在优化条件下, PC收率大于99%.     

Cellulose stabilized Fe3O4 and carboxylate-imidazole and Co-based MOF growth as an exceptional catalyst for the Knoevenagel reaction

In this study, Fe₃O₄ nanoparticles were functionalized with cellulose, and then hybridized with cobalt (II)-based metal-organic framework (Co-MOF) containing carboxylate and imidazole functionalities. FTIR, XRD, FE-SEM, TEM, BET, EDX, VSM and STA analyses were used to characterize the synthesized samples. The resultant Fe₃O₄/cellulose/Co-MOF nanocomposite was applied efficiently as a powerful and economic heterogeneous catalyst in the condensation of a variety of different aromatic aldehydes with malononitrile under solvent-free conditions at room temperature for 10 min and offered the corresponding coupling products in high yields. The catalyst could be straightforwardly separated by a magnet from the reaction mixture and reused without a noteworthy drop in catalytic activity at least five times. The use of Fe₃O₄/cellulose/Co-MOF catalyst outcomes under mild reaction conditions in very short reaction time, outstanding catalytic activity, high recyclability and an easy work-up process for Knoevenagel condensation.