金属有机骨架材料MIL-53(Al)负载钴催化剂的CO催化氧化反应性能

采用溶剂法合成了热稳定性高的金属有机骨架材料MIL-53(Al)(MIL:Materials of Institut Lavoisier),用此材料为载体负载钴催化剂用于CO的催化氧化反应,并与Al2O3负载的钴催化剂进行了对比.采用热重-差热扫描量热(TG-DSC)、傅里叶变换红外(FTIR)光谱、X射线衍射(XRD)、N2物理吸附-脱附、透射电子显微镜(TEM)、氢气程序升温还原(H2-TPR)等方法对催化剂的结构性质进行了表征.TG和N2物理吸附-脱附结果表明,载体MIL-53(Al)有好的稳定性和高的比表面积;XRD以及TEM结果表明Co/MIL-53(Al)上负载的Co3O4颗粒粒径(平均约为5.03 nm)明显小于Al2O3上Co3O4颗粒粒径(平均约为7.83 nm).MIL-53(Al)的三维多孔结构中分布均匀的位点能很好地分散固定Co3O4颗粒,高度分散的Co3O4颗粒有利于CO的催化氧化反应.H2-TPR实验发现Co/MIL(Al)催化剂的还原温度低于Co/Al2O3催化剂的还原温度,低的还原温度表现为高的催化氧化活性.CO催化氧化结果表明,MIL-53(Al)负载钴催化剂的催化活性明显高于Al2O3负载钴催化剂,MIL-53(Al)负载钴催化剂在160°C时使CO氧化的转化率达到98%,到180°C时CO则完全转化,催化剂的结构在催化反应过程中保持稳定.     

Pt/MIL-101(Cr)在肉桂醛选择性加氢反应中的催化性能

采用简单易行的浸渍法将Pt纳米粒子负载到MIL-101(Cr)上,制备了Pt/MIL-101(Cr)催化剂,并对其在肉桂醛选择性加氢反应的催化性能进行了研究。XRD、N₂吸附、TEM和催化性能的研究结果表明,Pt的负载量对负载于MIL-101(Cr)上Pt纳米粒子的尺寸及所制备催化剂对肉桂醇的选择性有很大影响。低Pt负载量(1.0%)的Pt/MIL-101(Cr)较其他MOFs和无机材料在肉桂醛选择性加氢反应中表现出了高的催化性能,在优化的反应条件下肉桂醛转化率和对肉桂醇的选择性可分别达96.5%和86.2%。Pt/MIL-101(Cr)催化剂具有良好的稳定性。Pt/MIL-101(Cr)所表现出的优良的催化性能同MIL-101(Cr)载体的孔道结构及其表面性质密切相关。     

Pt/MIL-101(Cr)在肉桂醛选择性加氢反应中的催化性能

采用简单易行的浸渍法将Pt纳米粒子负载到MIL-101(Cr)上, 制备了Pt/MIL-101(Cr)催化剂, 并对其在肉桂醛选择性加氢反应的催化性能进行了研究。XRD、N₂吸附、TEM和催化性能的研究结果表明, Pt的负载量对负载于MIL-101(Cr)上Pt纳米粒子的尺寸及所制备催化剂对肉桂醇的选择性有很大影响。低Pt负载量(1.0wt%)的Pt/MIL-101(Cr)较其他MOFs和无机材料在肉桂醛选择性加氢反应中表现出了高的催化性能, 在优化的反应条件下肉桂醛转化率和对肉桂醇的选择性可分别达96.5%和86.2%。Pt/MIL-101(Cr)催化剂具有良好的稳定性。Pt/MIL-101(Cr)所表现出的优良的催化性能同MIL-101(Cr)载体的孔道结构及其表面性质密切相关。     

金属有机骨架材料负载镍纳米颗粒催化硝基苯加氢

以MIL-53(Al)、MIL-96(Al)和MIL-120(Al) (MIL: Material Institute of Lavorisier)三种金属有机骨架材料为载体, 采用浸渍法制备了负载廉价金属镍纳米颗粒的催化剂. 将其用于催化硝基苯加氢合成苯胺反应, 发现以MIL-53(Al)为载体制得的催化剂表现出优异的催化性能. 采用不同的镍前驱体, 如硝酸镍、醋酸镍、乙二胺合镍, 制备了一系列Ni/MIL-53(Al)催化剂. 通过X射线衍射、傅里叶变换红外光谱、电感耦合等离子体、N₂物理吸附、H₂程序升温还原、透射电镜等技术对其进行了表征, 研究了镍前驱体对金属-载体相互作用、镍颗粒尺寸以及分散程度的影响.结果表明:以乙二胺合镍为镍前驱体制得的催化剂具有金属-载体相互作用适中、镍纳米颗粒更小(4-5 nm)和分布更均匀的特点, 在硝基苯加氢反应中表现出优异的催化性能, 硝基苯转化率达到100%.回收重复使用5次后, 此催化剂仍保持催化活性,硝基苯转化率达92%.     

苯部分加氢制环己烯新型Ru-B/MOF催化剂

制备了多种金属-有机骨架(MOF)材料,采用浸渍-化学还原法制备了非晶态Ru-B/MOF催化剂,考察了它们在苯部分加氢反应中的催化性能.催化性能评价结果表明,这些催化剂的初始反应速率(r0)顺序为Ru-B/MIL-53(Al)Ru-B/MIL-53(Al)-NH2Ru-B/UIO-66(Zr)Ru-B/UIO-66(Zr)-NH2Ru-B/MIL-53(Cr)Ru-B/MIL-101(Cr)Ru-B/MIL-100(Fe),环己烯初始选择性(S0)顺序为Ru-B/MIL-53(Al)≈Ru-B/MIL-53(Cr)Ru-B/UIO-66(Zr)-NH2Ru-B/MIL-101(Cr)Ru-B/MIL-53(Al)-NH2Ru-B/UIO-66(Zr)≈Ru-B/MIL-100(Fe).催化性能最好的Ru-B/MIL-53(Al)催化剂上的r0和S0分别为23 mmol·min-1·g-1和72%.采用多种手段,对催化性能差异最为显著的Ru-B/MIL-53(Al)和Ru-B/MIL-100(Fe)催化剂的物理化学性质进行了表征.发现MIL-53(Al)载体能够更好地分散Ru-B纳米粒子,粒子的平均尺寸为3.2 nm,而MIL-100(Fe)载体上Ru-B纳米粒子团聚严重,粒径达46.6 nm.更小的粒径不仅能够提供更多的活性位,而且也有利于环己烯选择性的提高.对Ru-B/MIL-53(Al)催化剂的反应条件进行了优化,在180°C和5 MPa的H2压力下,环己烯得率可达24%,展示了MOF材料用作苯部分加氢催化剂载体的良好前景.     

Tandem Catalysis of Ammonia Borane Dehydrogenation and Phenylacetylene Hydrogenation Catalyzed by CeO2 Nanotube/Pd@MIL-53(Al)

Heterogeneously catalyzed, selective hydrogenation in the liquid phase is widely used in industry for the synthesis of chemicals. However, it can be a challenge to prevent active nanoparticles (e.g., palladium) from aggregation/leaching and meanwhile achieve high conversion as well as selectivity, especially under mild conditions. To address these issues, a CeO₂ nanotube/Pd@MIL-53(Al) sandwich-structured catalyst has been prepared in which the MIL-53(Al) porous shell can efficiently stabilize the palladium nanoparticles. When this catalyst was used in a tandem catalytic reaction involving the dehydrogenation of ammonia borane and the hydrogenation of phenylacetylene, remarkably, the hydrogen released from the dehydrogenation of ammonia borane boosted the catalytic process, with 100 % conversion of phenylacetylene and a selectivity of 96.2 % for styrene, even at room temperature and atmospheric pressure, within 1 min. This work therefore provides an alternative strategy for balancing the conversion and selectivity of liquid-phase hydrogenation reactions.     

A 3D MIL-101@rGO composite as catalyst for efficient conversion of straw cellulose into valuable organic acid

Efficient conversion of straw cellulose to chemicals or fuels is an attracting topic today for the utilization of biomass to substitute for fossil resources. The development of catalysts is of vital importance.In this work, a composite catalyst metal-organic frameworks(MOFs) immobilized on three-dimensional reduced graphene oxide(3D-r GO) were synthesized by in situ growth of the MIL-101(Cr) within the 3Dr GO matrix. The supporting of 3D-r GO guaranteed the dispersion and acid site density of MI...     

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.     

Pd/MIL-101的制备及非均相催化吲哚C-H活化

水热合成MIL-101,过量浸渍法吸附Pd(OAc)_2,原位还原Pd~(2+)制得Pd/MIL-101催化剂.采用XRD、XPS、SEM、ICP、HRTEM和N_2吸/脱附实验对其结构进行表征,催化剂Pd纳米粒子尺寸在1.5~2.5 nm之间,含量为1.5%.催化实验表明,Pd/MIL-101能高效催化吲哚C_2位芳基化,对于活性较差的溴代芳烃,也能得到中等以上的收率,催化剂循环5次后仍能保持较高的反应活性,发展了吲哚C_2位衍生物的简单、高效的合成方法.     

A new Brønsted acid MIL-101(Cr) catalyst by tandem post-functionalization; synthesis and its catalytic application

A new heterogeneous Brønsted solid acid catalyst was prepared by tandem post-functionalization of MIL-101(Cr) and utilized for acetic acid esterification and alcoholysis of epoxides under solvent-free conditions. First, MIL-101(Cr) was functionalized with pyrazine to achieve MIL-101(Cr)-Pyz. Afterwards, the nucleophilic reaction of MIL-101(Cr)-Pyz with 1,3-propane sultone and next acidification with diluted sulfuric acid gave MIL-101(Cr)-Pyz-RSO₃H Brønsted solid acid catalyst. Various characterization methods such as Fourier transformation infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), elemental analysis (CHNS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersiveX-ray(EDX) spectroscopy, thermal analysis (TGA/DTA), acid–base titration, and N₂ adsorption/desorption analysis were employed to fully characterize the prepared catalyst. The catalyst showed high activity compared to unmodified MIL-101(Cr) in both catalytic acetic acid esterification and alcoholysis of epoxides. It can also be readily isolated from the reaction mixture and reused three times without major decrease in its activity.     

Oligomerization of ethylene in the presence of heterogenized complex catalytic systems based on ionic liquid‐type substituted zirconium phenolates

The oligomerization of ethylene was investigated in the presence of novel catalytic systems consisting of alkylaluminium chlorides and heterogenized zirconium phenolates containing amino and imino hydrochloride substituents. It was determined that the composition of a synthesized oligomer and the activity or selectivity of the catalyst systems depend on various parameters such as the molar ratio of Zr:Al, the composition of alkylaluminium, the temperature of the reaction, the pressure of ethylene and the structure of zirconium phenolates. The results showed that C₄‐C₁₀ linear α‐olefins were obtained with high selectivity when diethylaluminium chloride was used as a co‐catalyst. The process of the separation of a synthesized oligomer from the catalyst containing amino and imino hydrochloride ionic liquid substituents was carried out by simple decantation, and after this process zirconium complexes could be reused several times for successive ethylene oligomerizations.     

Selective ethylene oligomerization bearing hyperbranched bispyridylamine chromium catalyst

Two new hyperbranched bispyridylamine ligands and multinuclear chromium complexes were synthesized with 1.0?G hyperbranched macromolecules, 2-chloropyridine, 2-chloro-4-methylpyridine and CrCl₃(THF)₃ as raw materials. The structures of hyperbranched ligands and chromium complexes were characterized by UV, FT-IR, ¹H NMR, ESI-MS, and elemental analysis. These hyperbranched chromium complexes were evaluated as catalyst precursors by using MAO as activator in the oligomerization of ethylene. Effects of reaction temperature, reaction pressure, Al/Cr molar ratio, concentration of catalyst, solvent, and the structure of catalysts on the catalytic activity and product selectivity were investigated. The oligomerization results showed that with increase of reaction temperature, reaction pressure, and Al/Cr molar ratio, the catalytic activity increased and then decreased; the catalytic activity continuously decreased as the amount of catalyst increased. The products were mainly based on C₆ and C₈. Under optimized conditions, the catalytic system of hyperbranched NNN/Cr(III)/MAO led to activity of 1.26?×?10⁵ g/(mol·Cr·h) and 63.34% selectivity for C₆ and C₈.     

MIL-53系列金属有机骨架化合物的合成及在Strecker反应中的催化性能

通过改变金属中心和配体官能团，合成了4个MIL-53系列金属有机骨架化合物NH₂-MIL-53（Sc），NH₂-MIL-53（Al），MIL-53（Sc）和NO₂-MIL-53（Sc）；研究了它们在合成α-氨基腈的Strecker反应中的催化性能.结果表明，NH₂-MIL-53（Sc）对于Strecker反应具有优异的催化性能，并具有可重复使用性.通过对比NH₂-MIL-53（Sc）和NH₂-MIL-53（Al）的催化性能，分析了金属离子半径和金属中心不饱和配位点对Strecker反应的影响.通过对比NH₂-MIL-53（Sc）与MIL-53（Sc）的催化性能，证明了作为路易斯碱中心的氨基可通过与路易斯酸中心的协同作用，有效促进Strecker反应的进行.通过对比NO₂-MIL-53（Sc）与MIL-53（Sc）的催化性能，认为催化剂结构上的硝基对于Strecker反应的进行具有重要影响.最后，通过对比NH₂-MIL-53（Sc）、硝酸钪和2-氨基对苯二甲酸（ATA）配体对催化性能的影响，总结出催化剂在纳米尺度的孔道结构是提高Strecker反应选择性的关键因素.     

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%。     

Catalytic synthesis of methylene diphenyl dicarbamate from methyl phenyl carbamate and trioxane over sulfuric acid catalyst

Methylene diphenyl dicarbamate (MDC) was synthesized from methyl phenyl carbamate (MPC) and trioxane using sulfuric acid (H₂SO₄) as catalyst. The effects of reaction temperature, reaction time, molar ratio of reactants and the content of catalyst have been studied in details. The results showed that H₂SO₄ exhibited high catalytic activity with the merits of moderate reaction velocity. Under the conditions of n(MPC)/n(trioxane) = 3:1, reaction temperature of 95°C, reaction time of 3.5 h and 30% H₂SO₄, the conversion of MPC reached 99.0% with the selectivity of MDC 81.6%. Moreover, the H₂SO₄ catalyst was reused five times without obviously activity decrease. Based on the identification of byproducts, a possible reaction mechanism was proposed.     

沸石咪唑酯骨架结构材料ZIF-8催化Friedel-Crafts酰基化反应(英文)

A zeolite imidazolate framework,ZIF-8,was synthesized and characterized by dynamic laser light scattering,X-ray powder diffraction,scanning electron microscopy,transmission electron microscopy,thermogr...     

The effect of encapsulated Zn-POM on the catalytic activity of MIL-101 in the oxidation of alkenes with hydrogen peroxide

Zinc monosubstituted Keggin heteropolyanion [PZnMo₂W₉O₃₉]^5? was electrostatically bound to nanocages of MIL-101 polymer matrix. The Zn-POM@MIL-101 catalyst was characterized by XRD, N₂ adsorption, atomic absorption (AAS), and FT-IR spectroscopic methods. The catalytic activity of the new composite material, Zn-POM@MIL-101, was assessed in the oxidation of alkenes using aqueous hydrogen peroxide as oxidant. Zn-POM@MIL-101/H₂O₂ catalytic system demonstrated good catalytic activity in the oxidation reactions. Zn-POM@MIL-101 was reusable for three catalytic cycles. While the MIL-101 matrix is an active catalyst in these oxidation reactions, the presence of Zn-POM significantly changed the selectivity and reaction times.     

Hyperbranched bisphosphinoamine ligands: synthesis,characterization and application in ethylene oligomerization

Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph₂PCl) and CrCl₃(THF)₃ as raw materials. The hyperbranched PNP ligands and chromium complexes were characterized by FT-IR, ¹H NMR, ³¹P NMR, UV and ESI-MS. Comparing with the chromium complexes, the hyperbranched PNP ligands, in combination with Cr(III), and activation by methylaluminoxane (MAO) in situ generated species with better catalytic performance for ethylene oligomerization. The effect of solvent, chromium source, ligand/Cr molar ratio, reaction temperature, Al/Cr molar ratio and reaction pressure on the catalytic activity and product selectivity were studied. The results showed that with increase of ligand/Cr molar ratio, reaction temperature and Al/Cr molar ratio, the catalytic activity increased at first and then decreased. However, the catalytic activity continuously increased with increase of reaction pressure. Under the optimized conditions, the catalytic system of hyperbranched PNP/Cr(III)/MAO led to catalytic activity of 2.68 × 10⁵ g/(mol Cr·h) and 37.71% selectivity for C₆ and C₈.     

Triethanolamine/KI: A Multifunctional Catalyst for CO2 Activation and Conversion with Epoxides into Cyclic Carbonates

A catalytic system of triethanolamine/potassium iodide (KI) was proved to be efficient for the chemical fixation of CO₂ with epoxide. It was found that triethanolamine with dual function could activate both CO₂ and epoxides. Effects of parameters such as catalyst molar ratio and amount, reaction time, pressure, and temperature were studied systematically. As a result, 99% propylene oxide conversion as well as 99% propylene carbonate selectivity could be obtained under the optimal reaction condition. Furthermore, the catalyst was found to be applicable to a variety of terminal epoxides, providing the corresponding cyclic carbonates in good yields and selectivity. Moreover, the catalyst could be reused five times without loss of activity. This work presents an example of a cheap and efficient catalyst for the chemical fixation of CO₂ to high-value chemicals, which could help to improve the catalytic efficiency and decrease cost of products for larger applications.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Polymer-Supported Lewis Acid Catalysts. I. Polystyrene-Gallium Trichloride Complex

Polystyrene-divinylbenzene (5-7%) copolymer beads are combined with anhydrous gallium trichloride in CS₂ to form a stable complex containing 3.06% Cl (equivalent to 0.287 mmol GaCl₃/g complex beads). The complex showed good catalytic activity in organic synthetic reactions such as acetalation, esterification, ketal formation, etherification, and Friedel-Crafts alkylation. The catalyst can be reused several times without losing its activity and can be easily separated from the reaction mixtures.