共查询到20条相似文献,搜索用时 15 毫秒
1.
Hong Wei Wang Ying Ping Jia Da Bin Gao Jing Mei Yin Guang-Yun-Zhou Shen Min Li 《中国化学快报》2007,18(7):795-798
The photo-promoted carbonylation of chloroalkanes with carbon monoxide was carried out under ambient conditions with copper and cadmium salts catalysts. The results indicated that the corresponding esters were produced with three salt catalysts, i.e. CuBr2, CuCl2 and CdI2. Among these catalysts, CdI2 was the most efficient in terms of ester yield and selectivity, particularly, 60% yield and 75% selectivity in the carbonylation of chlorocyclohexane were achieved. Furthermore, the yield and selectivity of the ester can be improved greatly by adding tri-n-butylamine in the CuBr2 and CuCl2 catalyst systems. On the other hand, the carbonylation did not proceed with single CdCl2, however, the catalytic activity of CdCl2 was increased greatly with NaIá2H2O as additive. As a result, we suggest that iodide ion plays an important role in the catalyst system of the cadmium salts. 相似文献
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B. A. Komarov E. A. Dzhavadyan V. I. Irzhak A. G. Ryabenko V. A. Lesnichaya G. I. Zvereva A. V. Krestinin 《Polymer Science Series A》2011,53(6):502-509
The physical and mechanical properties of composite materials based on epoxy-amine systems—diglycidyl ether of diphenylolpropane-eutectic
mixture of aromatic amines (40 wt % m-phenylenediamine-60 wt % 4,4′-diaminodiphenylmethane) and epoxy-diane resin ED-20-eutectic mixture of aromatic diamines with
ultralow contents (≤0.1 wt %) of single-layer carbon nanotubes—are studied. It is shown that, for the concentration dependence
of the modulus of elasticity during tension, the additivity rule is obeyed only at the lowest concentrations of carbon nanotubes.
In this case, the presence of near-surface layers of a matrix with an increased elastic modulus should be considered. 相似文献
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Shaobin Wang Kazuhisa Murata Takashi Hayakawa Satoshi Hamakawa Kunio Suzuki 《Reaction Kinetics and Catalysis Letters》1999,68(2):265-270
Several metal oxides supported on sulfated zirconia catalysts were tested for the oxidative dehydrogenation of ethane into
ethylene by carbon dioxide. It is found that the catalytic behavior of supported oxide catalysts differ depending on the nature
of metal oxides. Chromium oxide-sulfated zirconia exhibits the highest ethane conversion and medium level of ethylene selectivity,
producing 38% ethylene yield at 50% ethane conversion at 650°C. 相似文献
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Wataru Ninomiya Yasuhiko Tanabe Ken-Ichiro Sotowa Toshiya Yasukawa Shigeru Sugiyama 《Research on Chemical Intermediates》2008,34(8-9):663-668
Dehydrogenation of decalin to naphthalene through tetralin and that of dicyclohexyl to biphenyl through phenylcyclohexane with Pt/C and Pd/C was investigated mainly under the liquid film state, in which the catalyst was just wet but not suspended and covered with a thin film of liquid substrate. To improve the catalytic activities, the effects of the addition of tellurium into Pd/C were investigated to reveal that the combination of tellurium, palladium and conjugated systems produced during the dehydrogenation of cycloalkames was important to the improvement of the activities. 相似文献
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《Surface and interface analysis : SIA》2018,50(7):734-743
Metal oxides have only recently begun to be used as catalysts for the growth of carbon nanotubes. Here, we propose a new model for the growth of carbon nanotubes, based on the intra‐granular charge transfer transition and the lattice strain of the catalyst nanoparticles. This is supported by results obtained from the doped metal oxides like samarium doped zinc oxide (SmZnO) and terbium doped zinc oxide (TbZnO). The intragranular charge transfer transition is believed to be responsible for the dissociation of the hydrocarbon molecules. The lattice strain of the catalyst nanoparticles appears to be responsible for the diffusion of carbon atoms through the catalyst particles. 相似文献
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Several carbon supported chromium oxide catalysts were prepared by varying textural and surface properties of support and
tested for methylene chloride oxidation. They were investigated by TGA and XPS. The difference in acidity and high valence
of chromium led to difference in activity.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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New tetravalent metal complexes with a trianionic [ONNO]-tetradentate ligand and an ancillary chloride ligand were synthesized as catalysts for the copolymerization of epoxides with carbon dioxide (CO(2)). All of the titanium, zirconium, germanium, and tin complexes were found to copolymerize epoxides with CO(2). In particular, the copolymerization of propylene oxide with CO(2) gave the almost-completely alternating copolymers by using titanium or germanium complexes. These results are the first example of the copolymerization using tetravalent metal complexes as a main component of catalysts. 相似文献
10.
Wen-Hua Zhang Sheau Wei Chien T.S. Andy Hor 《Coordination chemistry reviews》2011,255(17-18):1991-2024
This review summarises some recent developments of the metal complexes of hetero-functional hybrid ligands of C-, N-, O-, P- and S-donors. It highlights the ligand designs, synthetic pathways, structural motifs and catalytic prowess of these complexes. 相似文献
11.
Ichikawa S Tada M Iwasawa Y Ikariya T 《Chemical communications (Cambridge, England)》2005,(7):924-926
Chemoselective hydrogenation of halogenated nitrobenzenes over Pt/C catalysts proceeds effectively in supercritical carbon dioxide (scCO2) to produce halogenated anilines with excellent selectivity; the rate of the hydrogenation of nitro groups is markedly enhanced in scCO2 compared to the neat reaction, and the dehalogenation reaction is significantly suppressed. 相似文献
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Water-cooled metal collector tubes for atom-trapping atomic absorption spectrometry in air—acetylene flames are discussed, particularly for the more volatile elements such as cadmium and selenium which may be less efficiently trapped at the hotter surface of a silica tube. It was found that a nickel tube gave 3 times greater sensitivity than silica for the determination of cadmium but was oniy half as sensitive for the determination of selenium. No atomic absorption signal for copper could be obtained with a nickel collector tube. A copper tube was 3–4 times more sensitive than nickel for cadmium and selenium. Similar effects were observed for cadmium solutions containing 1000 ppm copper or nickel, and for selenium solutions containing 1000 ppm copper, with silica atom-trap tubes, but in both cases better results were obtained when the analyte solution of cadmium or selenium contained the co-element (1000 ppm) than when the cadmium or selenium was measured with a silica tube previously metallized with the co-element. 相似文献
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S. G. Khaminets L. L. Potapova V. Z. Radkevich Yu. G. Egiazarov 《Russian Journal of Applied Chemistry》2008,81(10):1764-1767
A number of supported-metal (Pt, Pd) catalysts based on Karbopon nonwoven carbon fibers were prepared by deposition from hydrosols and by ion exchange. The catalytic activity of the catalysts in low-temperature oxidation of carbon monoxide by atmospheric oxygen was determined. Catalyst samples were studied by transmission electron microscopy. 相似文献
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Electrochemical reduction of carbon dioxide has been attracting extensive interest due to its fundamental significance both in environmental protection and in energy storage. In this review, recent progress in the manipulation of the catalytic activity and selectivity of various transition metals towards CO2 reduction reaction (CO2RR) is summarized within the context of deliberate surface functionalization by select organic ligands. This is primarily manifested in three effects, interfacial charge transfer, suppression of hydrogen evolution, and stabilization of key reaction intermediates. The review is concluded with a perspective of the challenges and promises in the structural engineering of metal catalysts for enhanced CO2RR performance. 相似文献
15.
The variation of the ignition temperature of a carbon black impregnated with various amounts of manganese oxide and uranium oxide has been measured by a DTA method. The technique allows a rapid assessment to be made of sample reactivity and only small amounts (approximately 5 mg) are required. Correlation of sample reactivity by ignition temperature measurement and isothermal weight-loss data is shown. 相似文献
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En-Hui Yuan Yiming Niu Xing Huang Meng Li Jun Bao Yong-Hong Song Bingsen Zhang Zhao-Tie Liu Marc-Georg Willinger Zhong-Wen Liu 《Journal of Energy Chemistry》2023,(5):479-491
Oxidative dehydrogenation of propane with carbon dioxide(CO2-ODP) characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO2 to valuable CO.However, the existing catalyst is limited due to the poor activity and stability, which hinders its industrialization. Herein, we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI) for CO2-ODP. Characterization... 相似文献
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Imines can be reduced to afford synthetically important amines via a number of means, of which half-sandwich metal complex-effected reduction has gained particular prominence in the past one decade or so. This Feature Article aims to summarise the progress made with such metal catalysts, placing emphasis on our own work. The article covers transfer hydrogenation and hydrogenation, and finishes with a brief account of catalyst immobilisation and mechanistic understanding. 相似文献
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Saito T Ohshima S Xu WC Ago H Yumura M Iijima S 《The journal of physical chemistry. B》2005,109(21):10647-10652
Nanoparticle catalysts are essential and indispensable for all syntheses of single-walled carbon nanotubes (SWCNTs). We have prepared size-controlled Co, Co-Mo, and Fe-Mo nanoparticles by the reversed micelle method as the catalysts for the gas-phase pyrolytic synthesis of SWCNTs. From the investigation of the relation between the sizes of the nanoparticles and the alkyl-chain lengths of the cationic surfactants, dialkyldimethylammonium bromides, it has been found that the alkyl groups of the surfactants could play a role in controlling the sizes of the nanoparticles and that the alkyl chain of the surfactant should be preferably less than 10 carbon atoms at most to prepare smaller-size nanoparticles with a narrow size distribution. The reduction of the particle size increases the number of nanoparticles in the colloidal solution and leads to a higher yield of SWCNTs. 相似文献