Higashimurayama-shi, Japan
Higashimurayama-shi, Japan

Time filter

Source Type

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.


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 | Watanabe A.,Tohoku University | Dewa K.,Tohoku University | Matsukawa Y.,Tohoku University | And 6 more authors.
Journal of Nanoparticle Research | Year: 2014

The impact of nucleation behavior and particle size distribution on the morphology of carbon black, which is a type of carbon nanoparticle, is investigated using a fixed sectional approach by applying the detailed chemical kinetic reaction for our previous experimental work: the pyrolysis of benzene in an inert atmosphere. By comparing the numerical behavior of polycyclic aromatic hydrocarbons (PAHs) formation and nucleation with experimental configurations of carbon black, the impacts of the behavior of PAHs formation and nucleation on the configurations are discussed. The development rate of the particle size distribution increases with an increase in temperature, and the size of small particles (size below 10 nm) decreases with an increase in residence time. The sensitivity of the furnace temperature on the particle size distribution and morphology of carbon black were further investigated by performing the calculation with the temperature being constant. Although the nucleation rate is nearly identical between 1,850 and 2,000 K, the rate decreases below 1,750 K. The mole fraction decreases with an increase in temperature, especially at 2,000 K, although the differences are small below 1,850 K. To form the complex aggregate shapes, three requirements should be fulfilled: (i) large particle number concentration, (ii) high nucleation rate, and (iii) quench before small particles of size below 10 nm collide with large particles consisting of a log-normal distribution. With these requirements fulfilled, the aggregate shapes would become the most complex at 1,850 K with a residence time of around 40 ms for the current benzene pyrolysis. © 2014 Springer Science+Business Media.


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.


Ono K.,Tohoku University | Watanabe A.,Tohoku University | Dewa K.,Tohoku University | Matsukawa Y.,Tohoku University | And 6 more authors.
Chemical Engineering Journal | Year: 2014

The reasons why benzene-acetylene composition has an effect on the configuration of carbon black, which is a type of carbon nanoparticle, were investigated using a fixed sectional approach by applying the detailed chemical kinetic reaction for our previous experimental work: the pyrolysis of benzene-acetylene in an inert atmosphere. By comparing the calculated behavior of polycyclic aromatic hydrocarbon formation, nucleation, and the particle size distribution with experimentally observed configurations for carbon black, the impact of the benzene-acetylene composition on the configuration of carbon black is discussed. The nuclei mole fraction increases with additive concentration, which strongly affects the complexity of the aggregate shape. Specifically, when the amount of benzene added to 3.0. vol% acetylene is increased to 5.0. vol% benzene, the particle number concentration of 30-80-nm-sized particles, which are considered as primary particles or spherical aggregates, increases. The increase in the number concentration of 30-80-nm-sized particles contributes to the simplification of the aggregate shapes. When acetylene is added to 1.0. vol% benzene, although the particle size distribution at 200. ms begins to shift to a bimodal shape with the addition of 0.5. vol% acetylene, a log-normal shape clearly appears at 200. ms with the addition of 5.0. vol% acetylene because the nuclei mole fraction reaches equilibrium at 200. ms. Thus, if the reaction is quenched before small particles (<10. nm in size) collide with larger particles with a log-normal shape, the complexity of the aggregate shape increases. The results for both of these cases indicate that the calculated nucleation behavior and the particle size distribution describe the aggregate shapes obtained experimentally. © 2014 Elsevier B.V.


Ono K.,Tohoku University | Matsukawa Y.,Tohoku University | Dewa K.,Tohoku University | Watanabe A.,Tohoku University | And 8 more authors.
Combustion and Flame | Year: 2015

The feedstocks, including benzene, acetylene, and benzene with acetylene or 2-7 ring PAH, were pyrolyzed in an isothermal laminar flow at 1400-1650. K. The particle size distributions (PSDs) of soot and nascent soot were analyzed using a scanning mobility particle sizer (SMPS). The morphology of particles with the same mobility particle diameter was examined using a scanning electron microscope (SEM), where the grid was sampled via thermophoretic sampling assisted by a differential mobility analyzer (DMA). The soot produced by the pyrolysis of acetylene at 1400. K exhibited the highest number concentration and a log-normal distribution compared with those of the soot produced by the pyrolysis of benzene and the PAH additives. At 1500. K, the pyrolysis of PAHs with three or more rings with zigzag sites significantly increased the number concentration, although the added carbon concentration was smaller than that of acetylene. The addition of dibenzo[a,e]pyrene, which possesses three armchair sites, inhibited soot formation, suggesting that the bay site is easily formed and that the formation of anisotropic PAHs inhibits dimerization. The morphology of the soot formed by the addition of dibenzo[a,e]pyrene exhibited a primary particle diameter of 10. nm and similar primary particles, whereas the morphology of the soot formed by the addition of PAHs with zigzag sites clearly indicated a structure with a primary particle diameter of 20-40. nm. These observations indicate that the incipient soot is formed by the formation of dimers or small clusters of large PAHs via the mechanisms of aromatic molecule addition to aromatic radicals referred to as the PAH-addition cyclization (PAH-AC) mechanism at high temperatures, whereas moderate-sized PAHs developed via the hydrogen-abstraction-carbon-addition (HACA) mechanism form clusters and incipient soot at relatively low temperatures. © 2015 The Combustion Institute.


Matsukawa Y.,Tohoku University | Ono K.,Tohoku University | Dewa K.,Tohoku University | Watanabe A.,Tohoku University | And 6 more authors.
Combustion and Flame | Year: 2016

In this study, growth mechanisms of polycyclic aromatic hydrocarbons (PAHs) leading to soot formation were discussed. In addition, the effect of PAHs on soot nucleation was investigated by comparing the concentration of PAHs under sooting and non-sooting conditions. The feedstock ethylene was pyrolyzed in an isothermal laminar flow at 1150-1730. K with a residence time of 16-363. ms. Reaction pathways of PAH growth at each temperature were discussed using total ion chromatograms (TICs) of gas chromatography/mass spectrometry (GC/MS). These TICs suggest that the hydrogen-abstraction-carbon-addition (HACA) and methyl addition/cyclization (MAC) mechanisms are the main mechanisms for large PAHs at 1350. K and that phenyl addition/cyclization (PAC) also plays an important role at 1730. K. This paper was the identification of pathways previously rarely considered in soot models: the pathway via dimerization of acenaphthylene; the pathway from perylene to coronene; the pathway from tetraphene to benzo[k]tetraphene. Some significant peaks of aliphatic hydrocarbons were also detected in the TIC at 1730. K. The quantification of pyrolysates was examined by GC/MS with deuterides. At 1730. K, the number concentration of nascent soot increased along with the mole fraction of PAHs. Despite a relatively high mole fraction of PAHs with molecular masses of 200-300. u, no soot was observed at 1150. K. This indicates that such PAHs are not precursors of nascent soot. © 2016 The Combustion Institute.


Ono K.,Tohoku University | Yanaka M.,Tohoku University | Saito Y.,Tohoku University | Aoki H.,Tohoku University | And 3 more authors.
Chemical Engineering Journal | Year: 2013

A mixture of benzene and acetylene is pyrolyzed in an inert atmosphere to investigate the influence of the benzene-acetylene composition on the configurations of carbon black. The effects of benzene concentration, acetylene concentration, and furnace temperature on the mean primary particle diameter and the aggregate shape in carbon black are investigated. When the acetylene concentration is varied and the benzene concentration is made constant, aggregate shapes become complex with an increase in acetylene concentration. However, in the case where the acetylene concentration is greater than that of the benzene concentration, the variation of aggregate shapes is small with increasing acetylene concentration. The results of this study suggest that nucleation has progressed and aggregate shapes appear complicated when the ratio of the benzene concentration to the acetylene concentration is appropriate (in this study, the ratio is 2:1) and the furnace temperature is high. However, when the benzene or acetylene concentration is high, and the furnace temperature is low, aggregate shapes are simplified because of the formation of small polycyclic aromatic hydrocarbons (PAHs), which contributes to surface growth. © 2012 Elsevier B.V.


Patent
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.


The purpose of the present invention is to provide a carbon black capable of efficiently covering the surface of an electrode active material and enhancing the electric current collection effect as an electroconductive agent of a secondary cell. A carbon black comprising carbon black aggregates (2) in which the ratio PPA/d of the number of primary particles (1) (PPA) and the diameter d (nm) of the primary particles (1) is 8 or higher.

Loading ASAHI CARBON Co. collaborators
Loading ASAHI CARBON Co. collaborators