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1.
A facile strategy for encapsulation of metal complex guests into MOFs was proposed. This strategy involves pre-adsorbing metal salt on MOF, and then coordinating the metal ions with the organic ligand, as exemplified by encapsulation of tris(1,10-phenanthroline) Cu(II) complexes (CuPhen) in MIL-100(Al) (denoted as CuPhen/MIL). CuPhen encapsulated in MIL-100(Al) showed higher catalytic activity than the neat CuPhen and CuPhen encapsulated in zeolite-Y. The prepared CuPhen/MIL catalyst was stable and could be reused at least three times without significant loss in activity. This work is beneficial for the host–guest chemistry study and the development of new heterogeneous catalysts. 相似文献
2.
《Journal of the European Ceramic Society》2004,24(12):3399-3408
Ceramic reinforced metals are attractive because of their enhanced elastic modulus, high strength, tribological properties and low thermal expansion. Most work in this sector has focused on particle- or fiber-reinforced composites where the ceramic phase is not continuous. This work presents aluminium–alumina composites where both phases are interpenetrating throughout the microstructure. Ceramic preforms were produced with sacrificial pore forming agents leading to porosities between 50% and 67%. Pore wall microstructure was varied by changing the sintering temperature. Permeability and strength was measured for the porous preforms and infiltration results were compared with theoretical predictions based on capillary law and Darcian flow. A direct squeeze-casting process was used to infiltrate the preforms with aluminium resulting in an interpenetrating microstructure on both macropore and micropore scale. 相似文献
3.
Manuela Scarselli Luca Camilli Paola Castrucci Francesca Nanni Silvano Del Gobbo Eric Gautron Serge Lefrant Maurizio De Crescenzi 《Carbon》2012,50(3):875-884
A simple method to decorate multiwalled carbon nanotubes (MWCNTs) with Au, Ag and Cu nanoparticles is illustrated. The method consists in directly depositing the selected metals by thermal evaporation on the carbon nanotubes. Comparative measurements carried out on samples that differ in the quantity and type of the deposited metal, reveal that isolated discrete particles form on the nanotube outer wall for all three metals. The CNT-based composites have been investigated by scanning and transmission electron microscopy to determine the size, shape and distribution of the nanoparticles. The results indicate that the quantity of evaporated metal only affects the nanoparticle size and not the average particle density. Particle composition was determined by X-ray photoelectron spectroscopy study. The results are discussed in terms of metal nanoparticle–tube interactions, an important issue for the fundamental and practical applications of similar MWCNT based composites. 相似文献
4.
《Plastics, Additives and Compounding》2004,6(1):28
Plastics Additives & Compounding reports on products currently available for protecting plastics against the harmful effects of ultraviolet radiation and heat. 相似文献
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Influence of pretreatment condition of metal support on perf ormance of metal supported hexaaluminate catalyst for methane co mbustion 总被引:1,自引:0,他引:1
IntroductionCatalytic combustion of methane is one of themost promising processes to generateenvironmentally clean energy[1]. Hexaaluminate(HA) monolithic catalyst is regarded as one of thepotential catalytic materials u… 相似文献
7.
An incorporation model has been proposed and used to discuss the interaction between various metal oxides and -alumina. The dispersion capacities of various metal oxides are predicted and the surface hydroxyl group density on -alumina estimated, based on the assumption that the (110) plane is preferentially exposed on the surface of -alumina. These results are in good agreement with the available experimental data. 相似文献
8.
S. Ananda Kumar K. Shree Meenakshi T.S.N. Sankaranarayanan S. Srikanth 《Progress in Organic Coatings》2008
The present work discusses on the corrosion resistant behaviour of polymer metal bilayer coatings, viz. polyaniline (PANI), polyaniline–nickel (PANI–Ni), nickel–polyaniline (Ni–PANI), polyaniline–zinc (PANI–Zn) and zinc–polyaniline (Zn–PANI). The coatings were synthesized by means of cyclic voltametric method. The coatings thus obtained were uniform in nature and highly adherent to the mild steel substrate. The effectiveness of the coatings in preventing corrosion was tested by electrochemical impedance studies (EIS) using Nyquist and Bode plots and potentiodynamic polarization studies as well. Among the various coatings synthesized, the PANI–Zn coating was found to offer the maximum protection, followed by PANI–Ni coatings. Metal–PANI coatings were found to offer the least resistance to corrosion. The coatings thus obtained were characterized by scanning electron microscopic (SEM) analysis and the results are discussed. 相似文献
9.
Nanocrystalline 8 mol% yttria stabilized zirconia (YSZ) powder was synthesized using polyvinyl alcohol (PVA) as organic precursor and acidic solutions of yttrium oxynitrite and zirconium nitrate. Complex formation was established using Fourier transform infrared (FTIR) spectroscopy and solid state 13C nuclear magnetic resonance (NMR) spectroscopy. Thermal stability of the complex was investigated by thermogravimetric analysis (TGA). X-ray diffractometry (XRD) revealed formation of cubic phase YSZ at a temperature as low as 600 °C. The lattice parameter and average crystallite size were calculated from the XRD data. Particle size of the YSZ powder was investigated through transmission electron microscopy (TEM). The band gap of the sintered YSZ pellet was measured by UV–Vis-diffused reflectance spectroscopy (DRS). AC electrical conductivity was measured in air at 1 kHz frequency using a programmable RCL meter. The activation energy was calculated from the conductivity data at different temperatures using the standard Arrhenius equation. 相似文献
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J. Rao S. S. Anjum M. Craig J. R. Nicholls 《Journal of Coatings Technology and Research》2018,15(1):87-94
Nanocomposites involve the inclusion of one material into the layers of another material at a nanoscale level. Inspired by nature, nanocomposites material systems offer functionalities over their bulk forms which in some cases have evolved over millions of years. Here, thin film coatings have been fabricated by PVD sputtering, comprising a soft PTFE phase which is combined with a hard metallic NiTi phase. A series of coatings with PTFE ranging from 10 to 75 vol% have been prepared, and their surface energies and microstructures investigated. The surface energy of the nanocomposite films changes with the PTFE content, falling in the range between PTFE and NiTi with water contact angles between 80° and 102° for a thin film with 25 and 75 vol% of PTFE, respectively. Here, both TEM and EDX reveal PTFE forming along NiTi column boundaries. Coatings with PTFE content greater than 50 vol% failed due to a build-up of intrinsic stress. The degree of hybridization between NiTi and PTFE was found to be dependent on the PTFE layer thickness. SEM analysis of this coating reveals PTFE at the surface embedded within the NiTi matrix. 相似文献
12.
Geng-Geng Luo Di Sun Qin-Juan. Xu Na Zhang Rong-Bin Huang LiRong Lin Lan-Sun Zheng 《Inorganic chemistry communications》2009,12(5):436-439
Solution phase reaction of AgNO3 with a mixture of benzene-1,3,5-tricarboxylic acid (H3BTC) and heterocyclic 2-aminopyrimidine (APYM) under the ammoniacal conditions gives rise to a novel metal–organic coordination polymer Ag3(BTC)(APYM)2 (1). The structure of 1 possesses a unique three-dimensional (3D) framework with one-dimensional channels surrounded by carboxylato-supported Ag–Ag dimers, Ag–Ag chains, fully deprotonated [BTC]3? and APYM ligands. Moreover, 1 exhibits strong blue photoluminescence maximized at 464 nm at room temperature (λex = 383 nm) and upon cooling to 77 K, the emission spectrum seems narrowly red-shifted. 相似文献
13.
Sintered metal powder process (SMPP) is one of the high technology methods in ceramic–metal joining domain. The present study examines the effect of temperature and time of metalized layer sintering on the thickness and homogeneity of the joining layer, the leakage rate in alumina–copper joining zone, and also identifies the different phases formed during sintering. The samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). Microstructure studies indicate that sintering the metalized layer with a holding time of 90 min at the temperature of 1530 °C, and with an applied layer thickness of 50 μm with proper plating and brazing stages lead to a completely homogeneous joining zone with an adequate thickness (about 33 μm). The results of leak tests on alumina–copper specimen in this condition was less than 10?9 Pa l s?1. 相似文献
14.
Amine-functionalized MIL-101(Cr)-NH2 metal–organic frameworks (MOF-N)/epoxy nanocomposites with Excellent cure label and high thermal stability were developed. Structure–property relationship was discussed by comparison of the cure state, thermal and viscoelastic behavior of epoxy nanocomposites containing pristine MOF or MOF-N applying differential scanning calorimetry (DSC), thermogravimetric analysis, and dynamic mechanical analysis. Epoxy containing 0.3 wt% MOF-N exhibited high glass transition temperature (Tg) of 96°C compared with 85°C observed for epoxy/MOF system. Thus, MOF-N played the role of catalyst in epoxy/amine curing reaction. Correspondingly, a lower activation energy was obtained based on cure kinetics modeling based on DSC measurements. Besides, incorporation of low amount (0.5 wt%) MOF-N induced an early-state resistance against decomposition, featured by 11°C rise in decomposition temperature at 5% weight loss. This was ascribed to the formation of porous metallic oxides during thermal decomposition of MOF-N in the epoxy system acting as a heat barrier, which increased the activation energy of decomposition. Amine-functionalization considerably prevented from further oxidation of the inner part of the matrix. 相似文献
15.
Takashi Ushikubo Mitsuhiko Kurashige Teruyo Koyanagi Hiroto Ito Yoshihisa Watanabe 《Catalysis Letters》2000,69(1-2):83-87
W–P mixed metal oxide catalysts are active and selective for the gas-phase hydration of ethene to ethanol. The activity and
selectivity of this catalytic reaction depend on the W/P atomic ratio. However, ethene conversion slightly decreases at higher
W/(W + P) atomic ratio. The selectivity for ethanol increases with the W/P atomic ratio and reaches the highest value (92%)
at W0.81P0.19Ox. The W0.81P0.19Ox catalyst is less active than the conventional H3PO4/SiO2 catalyst, but the activity is maintained for a long time without the supply of any catalyst components. The reaction temperature
does not affect substantially the rate of ethene hydration over the W0.81P0.19Ox catalyst. The H2O/ethene molar ratio of 0.4 is the most appropriate for both reaction rate and selectivity. The active species of W–P mixed
metal oxide are amorphous. But there is Keggin structure of W–P oxide species (PW12O40
3−) in the presence of steam. And the species are the active sites for the hydration of ethene, confirmed by in situ Raman spectroscopy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
按配体类型,综述了近年来第ⅣB族非茂金属烯烃聚合催化剂研究进展,其配体类型包括:胺基类、酮亚胺类、吡唑类、苯氧亚胺类等。讨论了配体结构和电子效应对催化剂聚合活性及聚合物结构、分子量等的影响;概括了高活性第ⅣB族非茂金属烯烃聚合催化剂应具备的条件。 相似文献
17.
In this work, nanocrystalline M–Zn ferrites (M=Ni; Mn; Cu) with compositions of M1?xZnxFe2O4 (x=0.0, 0.2 and 0.4) were synthesized from metal nitrate precursors by rapid the sol–gel combustion method using diethanolamine (DEA) as the fuel. As-synthesized powders were calcined at 1000 °C for 4 h. The crystal structures and morphologies of these compounds were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. The chemical interaction of ferrite powders was investigated by Fourier transform infrared spectroscopy (FTIR). The magnetic properties of after-calcined nanoparticles were measured at room temperature using a vibrating sample magnetometer (VSM). The single phase spinel cubic structure formation is confirmed by XRD and FTIR results. Meanwhile FE-SEM micrographs show the appearance of both undoped and Zn-doped ferrite ceramic samples. In addition, the VSM analyses indicate that the Zn content has a significant influence on the magnetic properties such as saturation magnetization (Ms) and coercivity (Hc). 相似文献
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《Diamond and Related Materials》1999,8(10):1936-1943
Contacts to boron-doped, (100)-oriented diamond implanted with Si or with Si and B were formed and the effects of dose, implantation energy and anneal treatment on the specific contact resistance were examined. Ti/Au contacts on heavily implanted diamond (1016 Si ions cm−2, Ei=30 keV or 1017 Si and B ions cm−2, Ei=15 keV (Si) and Ei=10 keV (B)) had a specific contact resistance lower than the best contacts produced on unimplanted diamond. A specific contact resistance of (1.4±6.4)×10−7 Ω cm−2 was achieved following a 450°C anneal. The results were consistent with a reduction in barrier height brought about by silicide formation. Light silicon implantation (1013 ions cm−2) or relatively light dual implantation (B, Si<1016 ions cm−2) did not reduce the specific contact resistance. Increasing the diamond conductivity by 4×104 decreased the specific contact resistance by over three orders of magnitude, in agreement with the trend observed by Prins (J.F. Prins, J. Phys. D 22 (1989) 1562). 相似文献
20.
Parag P. Kulkarni Subodh S. Deshmukh Vladimir I. Kovalchuk Julie L. d'Itri 《Catalysis Letters》1999,61(3-4):161-166
Activated carbonsupported Group VIII noble metals formed CF2Cl2 oligomerization products under hydrodechlorination conditions. All the catalysts underwent deactivation during first 15–20 h on stream at 250°C independent of the H2 partial pressure, with steadystate activity following the order: Pt > Pd Ir > Ru Os Rh. The Pd/C catalyst exhibited high selectivity toward C2–C3 hydrocarbons (75% at CF2Cl2/H2 = 1). For the other catalysts except Pt, CF2=CF2 and CH2=CF2 were the main C2+ products. 相似文献