Hydrodynamics and gas mixing in a carbon nanotube agglomerate fluidized bed

Yu, Huimin; Zhang, Qunfeng; Gu, Guangsheng; Wang, Yao; Li, Guohua; Wei, Fei

doi:10.1002/aic.11031

Cited by 40 publications

(29 citation statements)

References 32 publications

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“…Fluidization in the various regimes recorded with a 2D bed showing a) channeling, b) agglomeration-bubbling-fluidization, c) turbulence, d) particulates, and e) defluidization. [217] 878 www.chemsuschem.org for ethylene, hydrogen, and iron were found to be 0.75, 0, and 0.28, respectively. [220] Simulation showed that the productivity of MWCNTs can reach 8 kg h À1 in a 45 cm diameter reactor operated under semi-batch conditions.…”

Section: Kinetics Of Cnt Growthmentioning

confidence: 95%

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Carbon Nanotube Mass Production: Principles and Processes

et al. 2011

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Our society requires new materials for a sustainable future, and carbon nanotubes (CNTs) are among the most important advanced materials. This Review describes the state-of-the-art of CNT synthesis, with a focus on their mass-production in industry. At the nanoscale, the production of CNTs involves the self-assembly of carbon atoms into a one-dimensional tubular structure. We describe how this synthesis can be achieved on the macroscopic scale in processes akin to the continuous tonne-scale mass production of chemical products in the modern chemical industry. Our overview includes discussions on processing methods for high-purity CNTs, and the handling of heat and mass transfer problems. Manufacturing strategies for agglomerated and aligned single-/multiwalled CNTs are used as examples of the engineering science of CNT production, which includes an understanding of their growth mechanism, agglomeration mechanism, reactor design, and process intensification. We aim to provide guidelines for the production and commercialization of CNTs. Although CNTs can now be produced on the tonne scale, knowledge of the growth mechanism at the atomic scale, the relationship between CNT structure and application, and scale-up of the production of CNTs with specific chirality are still inadequate. A multidisciplinary approach is a prerequisite for the sustainable development of the CNT industry.

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Section: Kinetics Of Cnt Growthmentioning

confidence: 95%

“…The expansion behavior of CNT products in a fluidized bed and typical images in the various fluidization regimes are shown in Figure 8. [217] As the gas velocity (U g ) increased, gas channeling occurred first in the bed, and the upper interface of the bed fluctuates strongly (Figure 8 a). With U g > 0.06 m s…”

Section: Multiphase Flow Behavior Of Cntsmentioning

confidence: 96%

Carbon Nanotube Mass Production: Principles and Processes

et al. 2011

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“…In this case, the higher metal loading on the catalyst for the DWCNT growth than that for the SWCNT growth makes it more difficult to avoid sintering than for the latter, when operated in the same high temperature range. Moreover, to synthesize bulk DWCNTs, it is necessary to control the concentration of the carbon source and the gas velocity [14], the thermal stability of the catalyst [10,11], the contact time of the catalyst with the carbon source [12], as well as the agglomerate structure of the carbon products [14] so that these are similar to those in the synthesis of MWCNTs [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of High‐Quality, Double‐Walled Carbon Nanotubes in a Fluidized Bed Reactor

et al. 2008

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Double-walled carbon nanotubes (DWCNTs) were synthesized in a packed bed reactor (PBR) and a fluidized bed reactor (FBR) by cracking CH 4 on a Fe/MgO catalyst. It is observed that the dominant carbon product changes drastically from DWCNTs to multi-walled CNTs along the axial direction of PBR. The studies indicated that the high concentration of H 2 from the high conversion of CH 4 causes the quick reduction and sintering of the iron catalyst and inhibits the nucleation of DWCNTs. Based on these results, the batch or continuous feeding mode of small amounts of catalyst was adopted in a FBR to maintain a high space velocity of CH 4 and to inhibit the negative effect of excess H 2 . Finally, a DWCNT product with a specific surface area of 950 m 2 /g and a purity of 98 %, was obtained.

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“…Some CNTs can link various catalysts loosely and keep them in the aggregating state. The aggregating properties of FWCNTs and catalysts particles, [16][17][18]33 as shown in Fig. 2(a) have given us the chance to successfully synthesize FWCNTs with the CCVD process in a fluidized bed reactor.…”

Section: Resultsmentioning

confidence: 99%

Few Walled Carbon Nanotube Production in Large-Scale by Nano-Agglomerate Fluidized-Bed Process

Zhang

Liu

et al. 2008

NANO

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Few walled carbon nanotubes (FWCNTs) have been successfully synthesized using a nanoagglomerate fluidized-bed process. FWCNTs can be obtained by fluidization of Fe(Co/Ni)/Mo/ MgO catalysts at a high temperature with methane cracking in a nano-agglomerate fluidizedbed reactor. The products were mainly 2 to 5 walled CNTs with an outer diameter of 1-7 nm in high purity, as revealed by Raman spectrometry, SEM, and HRTEM analysis. Two keys were crucial for this process. The first key was to get the small size of activity catalyst particles which was realized by Mo addition in catalyst. The graphitization of FWCNTs strongly depended on the composition of catalyst. Fe/Mo/MgO catalyst showed the highest activity and the FWCNT product with the best graphitization. Another key for this process was that the particles must be kept in fluidized state during FWCNT formation. Detailed process information was reported in this article, which showed a potential way for the large scale production of FWCNTs, thereby the urgent need for FWCNTs in high performance will be overcome. Keywords: Few walled carbon nanotube; fluidized bed; large scale. 45 NANO 2008.03:45-50. Downloaded from www.worldscientific.com by FUDAN UNIVERSITY on 05/14/15. For personal use only.

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Hydrodynamics and gas mixing in a carbon nanotube agglomerate fluidized bed

Cited by 40 publications

References 32 publications

Carbon Nanotube Mass Production: Principles and Processes

Carbon Nanotube Mass Production: Principles and Processes

Synthesis of High‐Quality, Double‐Walled Carbon Nanotubes in a Fluidized Bed Reactor

Few Walled Carbon Nanotube Production in Large-Scale by Nano-Agglomerate Fluidized-Bed Process

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