Time filter

Source Type

Higashimurayama-shi, Japan

Asahi Carbon Co. and Hokkaido University | Date: 2013-03-07

In the present invention, a starting material liquid including a carbon compound and a catalyst or a catalyst precursor, and a reaction vessel having a high-temperature zone heated to 900-1,300 C. are prepared. The starting material liquid is introduced into the reaction vessel, and a mixture is generated which comprises a gas including a carbon source, and catalyst microparticles dispersed in the gas. A carrier gas is then introduced in pulses into the reaction vessel, and the mixture is pushed out to the high-temperature zone. The carbon source and catalyst microparticles included in the mixture are then brought into contact with each other in the high-temperature zone, initial fibers are grown, and carbon fibers are subsequently grown in an environment in which the carrier gas is retained.

Watanabe R.,Tohoku University | Shindoh T.,Tohoku University | Matsushita Y.,Tohoku University | Aoki H.,Tohoku University | And 5 more authors.
Journal of Chemical Engineering of Japan | Year: 2010

In this study, a Monte Carlo simulation using an aggregate mean free path model is carried out for the aggregate formation of carbon black in the furnace process at different temperatures. A comparison of the results of two dimensional shape analysis of calculated aggregates and transmission electron microscope images of carbon black obtained from the furnace process shows that the aggregate shapes became complicated with an increase in temperature. In the furnace process, three factors (mean thermal velocity, particle number density, and primary particle diameter) vary simultaneously with temperature. Therefore, investigating the effect of each factor on the aggregate shape requires additional simulations while changing the individual factors. The results of two dimensional aggregate shape analysis shows that an increase in mean thermal velocity and particle number density contributes to complicating the aggregate shape and a decrease in primary particle diameter contributes to its simplification. On the other hand, the mean thermal velocity and particle number density are influenced by both the tempera-ture and primary particle diameter; a decrease in primary particle diameter obviously contributes greatly to an increase in these factors and indirectly contributes to complication of the aggregate shape. Therefore, primary particle diameter is the most important factor in controlling the aggregate shape of carbon black in the furnace process. © 2010 The Society of Chemical Engineers, Japan.

Nagao M.,Nagoya University | Kobayashi K.,Nagoya University | Yamamoto Y.,Nagoya University | Yamaguchi T.,ASAHI CARBON Co. | And 2 more authors.
ChemElectroChem | Year: 2016

Rechargeable proton-exchange membrane batteries that employ organic chemical hydrides as hydrogen-storage media have the potential to serve as next-generation power sources; however, significant challenges remain regarding the improvement of the reversible hydrogen-storage capacity. Here, we address this challenge through the use of metal-ion redox couples as energy carriers for battery operation. Carbon, with a suitable degree of crystallinity and surface oxygenation, was used as an effective anode material for the metal redox reactions. A Sn0.9In0.1P2O7-based electrolyte membrane allowed no crossover of vanadium ions through the membrane. The V4+/V3+, V3+/V2+, and Sn4+/Sn2+ redox reactions took place at a more positive potential than that for hydrogen reduction, so that undesired hydrogen production could be avoided. The resulting electrical capacity reached 306 and 258mAhg-1 for VOSO4 and SnSO4, respectively, and remained at 76 and 91% of their respective initial values after 50 cycles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dewa K.,Tohoku University | Ono K.,Tohoku University | Watanabe A.,Tohoku University | Takahashi K.,Tohoku University | And 8 more authors.
Combustion and Flame | Year: 2016

The effects of furnace temperature and residence time on particle size distributions (PSDs) of carbon black, which is a type of carbon nanoparticle, were studied with a scanning mobility particle sizer. Particles were classified according to their mobility diameters by a differential mobility analyzer, followed by thermophoretic sampling by scanning electron microscopy to investigate their carbon black morphologies. PSDs were power-law distributions at short residence times and log-normal distributions at long residence times; these distributions indicate that agglomeration increases with increasing residence time. In addition, few 2.5-nm-sized particles existed above 1540 ± 40 K, while the critical size was 3 nm at 1350 ± 40 K. This finding indicates that the critical size of nuclei changes with temperature. At high temperatures of 1776 and 1676 K, the 100 and 180-nm-sized particles, whose primary particles kept their shape, had very complex morphologies. In contrast, at low temperature at 1570 K, the morphologies of 100 and 180-nm-sized aggregates are relativity simple, and primary particles nearly fused together in those aggregates. These observations indicate that the nucleation rate and fusing behavior change with temperature. © 2015 The Combustion Institute.

Ono K.,Tohoku University | Yanaka M.,Tohoku University | Tanaka S.,Tohoku University | Saito Y.,Tohoku University | And 4 more authors.
Chemical Engineering Journal | Year: 2012

The effects of furnace temperature and residence time on the mean primary particle diameter and aggregate shape of carbon black are investigated by benzene pyrolysis to confirm the factors that control the configuration of carbon black. With a high furnace temperature and short residence time, the mean primary particle diameter decreases and the aggregate shapes are complex; on the other hand, with a low furnace temperature and short residence time, the mean primary particle diameter increases and the aggregate shapes are simple. Moreover, with a high furnace temperature and long residence time, the mean primary particle diameter increases and the aggregate shapes are relatively simple. However, the aggregate shapes remain basically unchanged with increasing residence time. The results of this study suggest that the main factors that control the configurations of carbon black are nucleation, surface growth and sintering of primary particles. Nucleation, which is affected by high-molecular-weight polycyclic aromatic hydrocarbons (PAHs), controls aggregate shapes, while surface growth, which is affected by low-molecular-weight PAHs contributes to the growth of primary particles. The sintering of primary particles controls the simplification of aggregate shape and the growth of primary particles. © 2012 Elsevier B.V.

Discover hidden collaborations