No abstract

In this study, we report a feasible way to synthesize carbon nanotube nanocomposites deposited with cobalt nanoparticles (20-30 nm) on the surface (Co/CNTs) to serve as an electromagnetic (EM) wave absorption material. EM absorption measurements indicated that epoxy resin composites with 20 wt% Co/CNTs exhibited an effective EM absorption (RL < -10 dB) in the frequency range of 2.5-20 GHz with an absorber thickness of 1.0 to 6.0 mm. A strong absorption peak (RL = -36.5 dB) appeared at 4.1 GHz as the thickness was 4.0 mm, and the absorption bandwidth (RL < -10 dB) was in the frequency range of 3.6-4.6 GHz. The electromagnetic loss research suggested that the superior EM absorption performances including a light weight, strong absorption, broad frequency scope, and thin thickness could be ascribed to the synergistic effect of magnetic loss from Co nanoparticles and the dielectric loss of CNTs, resulting in better impedance matching.

The chromium (III) oxide (Cr 2 O 3 ) nanoparticles embedded in the carbon sheets are fabricated by combining a sol-gel approach with an efficient carbonization process using glycine as carbon precursor. These Cr 2 O 3 /carbon nanocomposites serving as anode materials for lithium-ion batteries (LIBs) have been tested, exhibiting higher cycling (reversible capacity of 465.5 mAh g -1 after 150 cycles at a current density of 100 mA g -1 ) and rate performances (the discharge capacities of 448.7, 287.2, and 144.8 mAh g -1 at a current density of 200, 400, and 800 mA g -1 , respectively) than pure Cr 2 O 3 (reversible capacity of 71.2 mAh g -1 after 150 cycles at a current density of 100 mA g -1 and the discharge capacities of 174.4, 60.5, 29.5, and 13.6 mAh g -1 at a current density of 100, 200, 400, and 800 mA g -1 , respectively) due to the presence of carbon sheets, which efficiently buffer the volume change during the lithiation/delithiation and improve the electrical conductivity between Cr 2 O 3 nanoparticles.

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In this work, multi-walled carbon nanotubes (MWNTs) nanocomposites with homogenously anchored nanomagnetite of 10 ~ 20 nm prepared by a hydrothermal-annealing method have demonstrated serving as anode materials for lithium ion batteries (LIBs) with a specific capacity of 829 mAh g −1 after 50 cycles at a current density of 100 mA g −1 and a reversible capacity of 686 mAh g −1 at a current density of 200 mA g −1 for the nanocomposites with a weight ratio of 1:1, much larger than the specific capacity of 230 mAh g −1 after 50 cycles at a current density of 100 mA g −1 and a reversible capacity of 195 mAh g −1 at a current density of 200 mA g −1 for the MWNTs. The MWNTs in the nanocomposites could efficiently buffer the strain of volume change during the lithiation/delithiation and greatly improve the electrical conductivity of the electrodes. The superior electrochemical performances of the Fe 3 O 4 /MWNTs were analyzed to originate from the unique conductive network of MWNTs in the nanocomposites as well as the high capacity from the nanomagnetite.

The kinetics of hydrodenitrogenation (HDN) were systematically studied in an isothermally high-throughput reactor over three kinds of catalysts (CoMo, NiMo, and NiMoW) to produce clean diesel meeting the latest national standard of China. The influences of reaction temperature, reaction pressure, volume ratio of H2 to oil, and space time on hydrodenitrogenation were investigated to obtain kinetic parameters. Two kinetic models considering the influence of self-inhibition were proposed for the HDN reaction of diesel oil. The results of both models are satisfactory. Taking the two-lump model as an example, it could well predict the evolution of nitrogen-containing compounds’ concentration along the axial length of the reactor, and the simulation on the HDN activity of various catalyst stacking schemes is close to the experimental data, which proves that the model is applicable for the simulation of a catalyst stacking system. In addition, the concentration of nitrogen-containing compounds was predicted for the catalyst gradation model of different loading sequences.

The Zn2+-doped BaFe12O19 nanoplates synthesized by a facile approach exhibit superior cycling performances as anode material, attributing to the Zn2+ doping.

The kinetics of hydrodenitrogenation (HDN) was studied in an isothermally high-throughput reactor over three kinds of catalysts (CoMo, NiMo, NiMoW) to produce ultra-low sulfur diesel. The influences of reaction temperature, reaction pressure, volume ratio of H2 to oil and space time were systematically investigated to obtain kinetic parameters. By analyzing the reaction mechanism, two-lump kinetic model considering the influence of self-inhibition was proposed for the HDN reaction of diesel oil, and Levenberg-Marquard optimization method was used to estimate the model parameters. The model could well predict the evolution of nitrogen-containing compounds concentration along the axial length of reactor. Based on the two-lump kinetic model, the simulation on the HDN activity of various catalyst stacking schemes is close to the experimental data, which proves the model is applicable for catalyst stacking system. And the concentration of nitrogen-containing compounds was predicted for the catalyst gradation model of different loading sequences.