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  • Effect of process conditions on the synthesis of carbon nanotubes by catalytic decomposition of meth

    A new dual-composition catalyst based on Ni-Mo/MgO with high efficiency of producing carbon nanotubes (CNTs) from methane was reported recently. In the present article, with this type of catalyst, the impact of such experimental parameters as reaction temperature, reaction time,concentration of H2, flow rate ratio of CH4 to H2 on yield and graphitization were investigated, leading to the following optimal growth conditions:synthesized. Raman measurement indicated that the as-synthesized product was well-graphitized, and the purity was estimated over 95% by TG-DSC analysis. In terms of the above results, an explanation of high-efficiency formation of CNTs bundles and the co-catalysis mechanism of Ni-Mo/MgO were suggested....

    2020-11-11 22:33:38浏览:32 carbonNanotubescatalyticdecompositionyieldgraphitizationdegree

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  • Synthesis of bamboo-like carbon nanotubes by ethanol catalytic combustion technique

    Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion (ECC) technique with combustion method. Copper plate was employed as substrate,ethanol as carbon source,and iron chloride as catalyst precursor. The as-grown black powder was characterized by means of scanning electron microscopy,transmission electron microscopy and Raman spectroscopy. The results show that the thinner bamboo-like carbon nanotubes have a relatively good structure that the compartment layers are more regular,while the thicker carbon nanotubes have a relatively irregular bamboo-like structure:the proposed method is simple to synthesize bamboo-like carbon nanotubes and has some advantages,such as flexible synthesis conditions,simple setup,and environment-friendly....

    2020-10-22 17:35:41浏览:32 Bamboo-likecarbonNanotubesethanolcatalyticcombustiontechniquecompartment

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  • Gas and pressure effects on the synthesis of amorphous carbon nanotubes

    The effects of gas, pressure and temperature on the production of amorphous carbon nanotubes were investigated using an arc discharging furnace at controlled temperature. Co/Ni alloy powder was used as catalyst.The discharge current was 80 A and voltage was 32 V. The optimal parameters were obtained: 600℃ temperature, hydrogen gas and 500 torr pressure. The productivity and purity of amorphous carbon nanotubes are 6.5 gram per hour and 80%, respectively. The diameter of the amorphous carbon nanotubes is about 7-20 nm....

    2020-09-13 23:35:02浏览:24 amorphouscarbonNanotubesarcdischargeatcontrolledtemperatureeffectsof

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  • 热重分析技术在炭材料制备和功能化领域的应用

    热重分析是一种快速有效地研究材料结构性能的分析方法,广泛应用于炭材料研究领域.综述了热重分析技术在几种炭材料(碳纳米管、碳纤维、活性炭、碳微球和针状焦)制备和功能化研究中的应用.主要论述了利用热重分析研究炭材料的反应机理、热稳定性、高温抗氧化性、反应动力学、吸/脱附性能、负载物含量的测定等,并展望了热重分析的发展前景....

    2020-08-31 10:42:30浏览:54 热重分析碳纳米管碳纤维活性炭碳微球thermogravimetricAnalysiscarbonNanotubesfibers

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  • Electrocatalytic oxidation of methanol on carbon-nanotubes/graphite electrode modified with platinum

    Electrochemical codeposition and electrocatalytic properties of platinum and molybdenum oxide nanoparticles (Pt-MoOx) on carbon-nanotubes/graphite electrode for methanol oxidation were investigated. The micrograph and elemental composition of the resulting Pt-MoOx/CNTs/graphite electrode were characterized by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS). The results show that the Pt-MoOx particles with the average size of about 50 nm are highly dispersed on the CNTs surface. The Pt-MoOx/CNTs/graphite electrode delivers excellent electrocatalytic properties for methanol oxidation. The highest mass activity(Am) reaches 264.8 A/g at the loading mass of 159.3 (g/cm2. This may be attributed to the small particle size and high dispersion of Pt-MoOx catalysts deposited on the CNTs surface. The kinetic analysis from electrochemical impedance spectroscopy(EIS) reveals that the existed MoOx phase can improve the chemisorptive and catalytic properties for methanol oxidation....

    2020-07-08 21:52:19浏览:27 methanoloxidationcarbonNanotubesMolybdenumoxidesNanoparticlesfuelcells

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  • Study on Highly Active Catalysts and a Once-Through Process for Methanol Synthesis from Syngas

    Highly active CNT-promoted co-precipitated Cu-ZnO-Al2O3 catalysts, symbolized asCuiZnjAlk-x%CNTs, were prepared, and their catalytic activity for once-through methanol synthesis fromsyngas was investigated. The results illustrated that, under the reaction conditions (at 493 K, 5.0 MPa, thevolume ratio of H2/CO/CO2/N2= 62/30/5/3, GHSV= 4000 h-1), the observed single-pass CO-conversionand methanol-STY over a Cu6Zn3Al1-12.5%CNTs catalyst reached 64% and 1210 mg/(h@g), which wasabout 68% and 66% higher than those (38% and 730 mg/(h@g)) over the corresponding CNT-free catalyst,Cu6Zn3Al1, respectively. The characteristic studies of the catalysts revealed that appropriate incorporationof a minor amount of the CNTs into the CuiZnjAlk brought about little change in the apparent activationenergy of the methanol synthesis reaction, however, led to a considerable increase in the catalyst's active Cusurface area and pronouncedly enhanced the stationary-state concentration of active hydrogen-adspecieson the surface of the functioning catalyst, which would be favorable to increasing the rate of the CO hydro-genation reactions. Moreover, the operation temperature for methanol synthesis over the CNT-promotedcatalysts can be 10-20 degrees lower than that over the corresponding CNT-free contrast system, whichwould contribute considerably to an increase in equilibrium CO-conversion and CH3OH-yield....

    2020-07-08 21:52:19浏览:22 carbonNanotubesCuiZnjAlk-x%CNTscatalystmethanolsynthesis

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  • Carbon Nanotubes Supported Pt-Ru-Ni as Methanol Electro-Oxidation Catalyst for Direct Methanol Fuel

    Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure.The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst....

    2020-07-08 21:52:19浏览:17 carbonNanotubesmethanolelectro-oxidationdirectfuel

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  • Synthesis of carbon nanotubes by catalytic pyrolysis method with Feitknecht compound as precursor of

    Carbon nanotubes are synthesized by catalytic pyrolysis method with a kind of new type catalyst--nickel-zinc-alumina catalyst prepared from Feitknecht compound. Tubular carbon nanotubes, bamboo-shaped carbon naotubes, herringbone carbon nanotubues and branched carbon nanotubes are all found formed at moderate temperature. It is important for the formation of quasi-liquid state of the metal nanoparticles at the tip of carbon naotubes during the growth of carbon nanotubes to lead to different kinds of carbon nanotubes. It is likely that the addition of zinc make the activity of nickel catalyst after calcinations and reduction changed strangely....

    2020-07-08 21:52:19浏览:31 carbonNanotubesFeitknechtcompoundnickel-zinc-aluminacatalystcatalytic

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  • Highly conjugated water soluble CdSe quantum dots to multiwalled carbon nanotubes

    Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions....

    2020-07-08 08:49:41浏览:29 MultiwalledcarbonNanotubesquantumdotsHeterojunctions

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  • 不同热解条件下硬脂酸根插层水滑石热解时形态变化的研究

    采用共沉淀法合成了镁铝物质的量比为3的硬脂酸根插层水滑石,利用FT-IR、TEM等技术分析了不同焙烧温度和焙烧时间对该水滑石焙烧产物的组分及形貌的影响,获得了至今尚未见报导的卷曲较清晰完整的纳米管状的焙烧产物....

    2020-03-24 09:18:20浏览:1405 水滑石焙烧组分形貌纳米管HydrotalciteCalcinationcomponentmorphologyNanotubes

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