新型多孔莫来石纤维陶瓷负载La0.8Sr0.2CoO3-δ钙钛矿催化剂

 利用空气挤压排液成型法在 1250 ℃下制得了高孔隙率高热稳定性的莫来石纤维陶瓷. 这种多孔莫来石纤维陶瓷具有较均匀的孔分布,并且孔隙率高达96.22%. 以这种多孔陶瓷为载体制备了负载型La0.8Sr0.2CoO3-δ钙钛矿催化剂,该催化剂对NO氧化CO表现出很好的催化活性和稳定性. 在催化剂中掺入贵金属Pd之后,催化剂的催化活性得到了很大的提高.     

A homochiral porous metal-organic framework for highly enantioselective heterogeneous asymmetric catalysis

A homochiral porous noninterpenetrating metal-organic framework (MOF), 1, was constructed by linking infinite 1D [Cd(mu-Cl)2]n zigzag chains with axially chiral bipyridine bridging ligands containing orthogonal secondary functional groups. The secondary chiral dihydroxy groups accessible via the large open channels in 1 were utilized to generate a heterogeneous asymmetric catalyst for the addition of diethyzinc to aromatic aldehydes to afford chiral secondary alcohols at up to 93% enantiomeric excess (ee). Control experiments with dendritic aromatic aldehydes of different sizes indicate that the heterogeneous asymmetric catalyst derived from 1 is both highly active and enantioselective as a result of the creation of readily accessible, uniform active catalyst sites inside the porous MOF.     

壳聚糖/硝酸铁凝胶制备铁氮掺杂多孔碳片作为高效氧还原电催化剂的研究

以壳聚糖/硝酸铁凝胶为前躯体,实现了含氮高分子与金属盐的均匀混合,将凝胶冷冻干燥处理后,经过热处理和酸刻蚀得到了成分及微结构更加均匀的铁氮掺杂多孔碳片. 铁氮掺杂多孔碳片与商业铂碳相比,具有更高的起始电位,半波电位和优秀的循环性能,在碱性燃料电池的测试中实现了更高的功率密度. 铁氮掺杂多孔碳片出色的氧还原电催化性能归因于铁在壳聚糖中的原子级分散所导致的均匀分布的铁氮碳催化活性位,大的比表面积和均匀的孔道分布.     

Co-and N-doped carbon nanotubes with hierarchical pores derived from metal-organic nanotubes for oxygen reduction reaction

Biomolecules with a broad range of structure and heteroatom-containing groups offer a great opportunity for rational design of promising electrocatalysts via versatile chemistry.In this study,uniform folic acid-Co nanotubes(FA-Co NTs) were hydrothermally prepared as sacrificial templates for highly porous Co and N co-doped carbon nanotubes(Co-N/CNTs) with well-controlled size and morphology.The formation mechanism of FA-Co NTs was investigated and FA-Co-hydrazine coordination interaction together with the H-bond interaction between FA molecules was characterized to be the driving force for growth of one-dimensional nanotubes.Such distinct metal-ligand interaction afforded the resultant CNTs rich Co-N_x sites,hierarchically porous structure and Co nanoparticle-embedded conductive network,thus an overall good electrocatalytic activity for oxygen reduction.Electrochemical tests showed that Co-N/CNTs-900 promoted an efficient 4 e ORR process with an onset potential of 0.908 V vs.RHE,a limiting current density of 5.66 mA cm^-2 at 0.6 V and a H_2 O_2 yield lower than 5%,comparable to that of 20%Pt/C catalyst.Moreover,the catalyst revealed very high stability upon continuous operation and remarkable tolerance to methanol.     

SnO2纳米材料的制备及其对丙烯醛还原反应的催化性能

 采用柠檬酸法制备了SnO2纳米材料,并采用差热-热重、 X射线衍射、透射电子显微镜和氮吸附等技术对其进行了表征,考察了其在丙烯醛还原制烯丙醇反应中的催化性能. 结果显示,制备的SnO2纳米材料粒径(尺寸为8～10 nm)均一, 并具有多孔性质(孔径4～6 nm); 在丙烯醛还原制烯丙醇反应中具有良好的催化性能,催化剂的初始活性很高,丙烯醛的初始转化率可达93.6%, 烯丙醇的最高选择性为60%, 烯丙醇的最高收率为47%. 表面结焦是造成催化剂失活的主要原因.     

金属有机骨架高温自还原制备高性能等级孔碳负载Co基催化剂

以钴基金属有机框架为前驱体, 利用一步高温碳化自还原法, 通过精确调控碳化过程, 实现等级孔道结构及钴纳米颗粒分散性的可控调节, 制备出高催化活性及产物选择性的等级孔碳负载Co基催化剂. 研究发现, 600 ℃碳化后的催化剂为具有高比表面积的等级孔道结构和高分散的钴纳米颗粒, 在选择性催化1,3-丁二烯加氢反应中, 丁二烯完全转化温度低至60 ℃, 对应丁烯的选择性高达61%, 实现了低温高选择性催化加氢.     

Preparation and Characterization of Porous Silica Films by a Modified Base-Catalyzed Sol-Gel Process Containing PVA: I. The Precursor Solution Synthesis

A novel modified base-catalyzed Sol-Gel process containing polyvinyl alcohol (PVA) has been proposed to prepare the porous SiO₂ film. In this process, the growth of the sol particles was artificially broken off and controlled by acid-stabilising agent and PVA. As a result, a uniform and stable precursor solution was obtained in which the size of sol particles was stable. This new process efficiently overcomes the shortcomings of the traditional base-catalysed Sol-Gel process and can be employed to prepare porous SiO₂ films with desired porosity and thickness. The influence of the catalyst, the reaction temperature, the pH value, the stabilizing agent and the PVA additive on the size of the SiO₂ sol particles is systematically studied in part I.     

Novel Synthesis of Cu-Schiff Base Complex@Metal-Organic Framework MIL-101 via a Mild Method: A Comparative Study for Rapid Catalytic Effects

The use of metal complex immobilized/decorated porous materials as catalysts has found various applications. As such, finding a new and mild method for synthesis of metal complex immobilized over porous material is of great interest. Immobilized porous materials for styrene oxidation were reported in this work. Immobilized porous material of Cu-Schiff base complex @MIL-101 were described, in which immobilized Cu-Schiff base complex within super cage of a metal-organic framework (MOF)-based porous material, chromium (III) terephthalate MIL-101. They were systematically characterized by using elemental analysis, powder X-ray diffraction, fourier transform infrared spectroscopy, N₂ absorption-desorption, and so on, also used as catalyst for the selective oxidation of styrene to benzaldehyde. Comparatively, the immobilized heterogeneous catalyst of Cu-Schiff base complex@MIL-101 acted as an efficient heterostructure catalyst in the oxidation of styrene to benzaldehyde up to six cycles, and showed superior activity for styrene oxidation over MIL-101.     

Enhanced Dual Fuel Cell Electrocatalysis with Trimetallic PtPdCo Mesoporous Nanoparticles

The facile preparation of platinum‐based catalysts with designed compositions and structures is of great importance for fuel cells. In this work, a one‐pot method is developed to synthesize monodispersed trimetallic PtPdCo mesoporous nanoparticles (PtPdCo MNs) with uniform morphology and size. The proposed synthetic method does not require any hard template or organic solvent, which greatly simplifies the preparation procedure. PtPdCo MNs, with a highly porous structure, exhibit enhanced electrocatalytic activities and excellent stabilities for both the formic acid oxidation reaction and the oxygen reduction reaction, relative to bimetallic PtPd MNs and commercial Pt/C catalyst. The proposed synthetic method is highly valuable for the design of mesoporous multimetallic catalysts for fuel cells.     

Ethylene polymerization with porous polystyrene spheres supported Cp2ZrCl2 catalyst

A catalyst with porous polystyrene beads supported Cp₂ZrCl₂ was prepared and tested for ethylene polymerization with methylaluminoxane as a cocatalyst. By comparison, the porous supported catalyst maintained higher activity and produced polyethylene with better morphology than its corresponding solid supported catalyst. The differences between activities of the catalysts and morphologies of the products were reasonably explained by the fragmentation processes of support as frequently observed with the inorganic supported Ziegler–Natta catalysts. Investigation into the distribution of polystyrene in the polyethylene revealed the fact that the porous polystyrene supported catalyst had undergone fragmentation during polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3313–3319, 2003     

Tungsten Nitride‐Cobalt Anchored in N‐Doped Ordered Porous Carbon as an Efficient Oxygen Reduction Reaction Electrocatalyst

We prepared a non‐precious‐metal tungsten nitride‐cobalt (WN‐Co) electrocatalyst anchored in nitrogen‐doped ordered porous carbon (NOPC) through an in situ method. The WN‐Co/NOPC electrocatalyst possesses good oxygen reduction reaction (ORR) capability in alkaline media, including a high onset potential of −132 mV, a dominant four‐electron process, and a superior stability (onset potential and limiting current density were almost unchanged after 5000 cycles in 0.1 m KOH). The improved ORR performance was comparable to that of WN/NOPC and Co/NOPC with regard to three aspects: the even dispersion and uniform size of electrocatalyst particles provide more reactive sites; the nitrogen doping, high specific surface area and highly ordered mesoporous channel of catalyst support (NOPC) are conducive to the infiltration of the electrolyte; the existence of WN reinvests the catalyst with good stability, and the anchored configuration of WN and Co in the NOPC will prevent the particles from agglomerating after a long‐term cycle, thereby improving the stability of the catalyst particles.     

Prussian Blue‐Derived Iron Phosphide Nanoparticles in a Porous Graphene Aerogel as Efficient Electrocatalyst for Hydrogen Evolution Reaction

Tailoring of new hydrogen evolution reaction (HER) electrocatalyst with earth abundant elements is important for large scale water splitting and hydrogen production. In this work, we present a simple synthetic method for incorporating iron phosphide (FeP) particles into three‐dimensional (3D) porous graphene aerogel (GA) structure. The FeP formed in porous 3D GA (FeP/GA) is derived from electroactive Fe hexacyanoferrate (FeHCF). The advantage of incorporating FeP, in the porous 3D graphene network enables high accessibility for HER. As synthesized FeP/GA catalyst shows good electrocatalytic activity for HER in both acidic and alkaline solutions. The developed method can be useful for synthesizing metal hexacyanoferrate derived mono/bimetal phosphide catalyst in porous 3D graphene aerogels.     

Urea‐based amphiphilic porous organic polymer‐supported palladium as a reusable catalyst for Suzuki–Miyaura coupling and hydroxycarbonylation reactions in water

The development of environmentally friendly heterogeneous catalysts for organic reactions in water is becoming of growing importance for the development of sustainable processes. In this work, a porous organic polymer‐supported palladium catalyst (Pd@UPOP‐1) was successfully fabricated from 3,3′‐diaminobenzidine and methylenediphenyl diisocyanate through a facile urea‐forming condensation reaction. The structure and composition of the catalyst were characterized using several physicochemical methods. Pd@UPOP‐1 was found to possess good porous structure and excellent amphiphilicity. Under mild reaction conditions, the catalyst showed excellent catalytic activity and good substrate compatibility for the Suzuki–Miyaura coupling reaction of aryl bromides, as well as the hydroxycarbonylation reaction of aryl iodides. In addition, the catalyst could be used for several consecutive recycles in both cases.     

UiO-67-Sal-CuCl2在空气中催化芳香醇的选择性氧化

利用水热法一步合成了金属有机骨架(MOFs)材料UiO-67-Sal, 并将3种铜盐固定在其表面, 研究了3种铜MOFs材料催化芳香醇选择性氧化的性能. 结果表明, UiO-67-Sal-CuCl₂催化剂对芳香醇选择性氧化反应具有良好的催化活性, 且在重复使用4次后, 依然保持较好的催化效果.     

A Facile Method for the Preparation of Monodisperse Beads with Uniform Pore Sizes for Cell Culture

This paper describes a facile method for the preparation of porous gelatin beads with uniform pore sizes using a simple fluidic device and their application as supporting materials for cell culture. An aqueous gelatin droplet containing many uniform toluene droplets, produced in the fluidic device, is dropped into liquid nitrogen for instant freezing and the small toluene droplets evolve into pores in the gelatin beads after removal of toluene and then freeze‐drying. The porous gelatin beads exhibit a uniform pore size and monodisperse diameter as well as large open pores at the surface. Fluorescence microscopy images of fibroblast‐loaded gelatin beads confirm the attachment and proliferation of the cells throughout the porous gelatin beads.     

多孔碳材料的制备

多孔碳材料不仅具有碳材料化学稳定高、导电性好等优点,由于多孔结构的引入,还具有比表面积高、孔道结构丰富、孔径可调等特点,在催化、吸附和电化学储能等方面都得到了广泛的应用。本文综述了微孔、介孔、大孔及多级孔碳等多孔碳材料的最新研究进展,重点介绍了多孔碳孔道结构的调控,并对多孔碳材料的应用进行了展望。     

浸渍Nafion溶液于PEMFC电极催化层中的新方法

本文发展了一种利用毛细作用于自制的疏水电极催化层中浸渍质子导体新方法 ,该电极用于PEMFC ,与传统的喷涂法相比 ,电池性能高 .循环伏安法测得催化剂利用率高 ,电极横截面的SEM和EDX对硫和催化剂铂的线形扫描分析发现 ,该情况下树脂在催化层中分布比较均匀 ,且几乎与催化剂铂的分布深度接近 ,而树脂在传统方法所得的电极催化层中则分布不均匀 ,而且渗进了扩散层 ,极易在阴极被水淹没 (flood)     

Single atomic Co coordinated with N in microporous carbon for oxygen reduction reaction obtained from Co/2-methylimidazole anchored to Y zeolite as a template

Zeolite-templated carbons (ZTCs) composed of curved and single-layer graphene frameworks have uniform micropores (ca. 1.2 nm) and high surface areas (~4,000 m²/g). Owing to their outstanding properties originating from the porous structures, ZTCs have been used in many applications. In this work, we synthesized Co/N-doped ZTC (Co/N-ZTC) by complexing Co ion with 2-methylimidazole in Y zeolite to expand further utilization of ZTCs. The obtained Co/N-ZTC has a high surface area (ca. 2,000 m²/g) and single atomic Co species in CoN_x moieties, which actually contributes to its excellent catalytic performance on oxygen reduction reaction. This synthetic concept is beneficial to fabricate single atomic transition metals coordinated with heteroatoms in ZTCs, which contributes to the progress of material design of single atomic catalyst–supported porous materials.     

Comparison of Syndiotactic Polystyrene Morphology Obtained Via Heterogeneous and Homogeneous Polymerization with Metallocene Catalyst

Summary: Supported catalyst system for the slurry phase polymerization of styrene in toluene was prepared by the immobilization of 2-methylindenyltrichlorotitanium(2-MeIndTiCl₃) on silica and activation of this catalyst was performed by methylaluminoxane(MAO) in polymerization media. Homogeneous polymerization of styrene with 2-methylindenyltrichlorotitanium activated by MAO was performed in toluene. The morphology of obtained syndiotactic polystyrene (sPS) via heterogeneous and homhgeneous catalyst system was compared. Polymerization of styrene by homogeneous catalyst lead to formation of gel and resultant polymers presented a compact and dense texture while the global gelation do not occur with silica supported catalyst at different Ti/SiO₂ mol ratios and sPS was obtained as separated particles. Unlike to the homogeneous catalyst, obtained polymers showed a porous texture. Highly porous texture of sPS was obtained with Ti/SiO₂ = 0.5% mol ratio.