CVD-synthesis of multiwall carbon nanotubes over potassium-doped supported catalysts

Balogh, Zoltán; Halasi, Gyula; Korbély, Barbara; Hernádi, Klára

doi:10.1016/j.apcata.2008.04.019

Cited by 25 publications

(17 citation statements)

References 19 publications

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“…Various oxides can be used as support or as structural promoter to enhance the dispersion of the active phase such as Co nanoparticles and to improve the yield of CNTs [12][13][14][15][16]. The catalytic system for CNT synthesis can be considered as sacrificial catalyst, where both the active phase and the oxidic components remain in the product as impurities.…”

Section: Introductionmentioning

confidence: 99%

Optimizing the synthesis of cobalt-based catalysts for the selective growth of multiwalled carbon nanotubes under industrially relevant conditions

Becker

Xia

Tessonnier

et al. 2011

Carbon

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A An industrially applicable cobalt-based catalyst was optimized for the production of multiwalled carbon nanotubes (CNTs) from ethene in a hot-wall reactor. A series of highly active Co-Mn-Al-Mg spinel-type oxides with systematically varied Co : Mn ratios was synthesized by precipitation and calcined at different temperatures. The addition of Mn drastically enhanced the catalytic activity of the Co nanoparticles resulting in an extraordinarily high CNT yield of up to 249 gCNT/gCat. All quaternary catalysts possessed an excellent selectivity towards the growth of CNTs. The detailed characterization of the obtained CNTs by electron microscopy, Raman spectroscopy and thermogravimetry demonstrated that a higher Mn content results in a narrower CNT diameter distribution, while the morphology of the CNTs and their oxidation resistance remains rather similar. The temperature-programmed reduction of the calcined precursors as well as in-situ X-ray absorption spectroscopy investigations during the growth revealed that the remarkable promoting effect of the Mn is due to the presence of monovalent Mn(II) oxide in the working catalyst, which enhances the catalytic activity of the metallic Co nanoparticles by strong metal-oxide interactions. The observed correlations between the added Mn promotor and the catalytic performance are of high relevance for the production of CNTs on an industrial scale.

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Section: Introductionmentioning

confidence: 99%

Optimizing the synthesis of cobalt-based catalysts for the selective growth of multiwalled carbon nanotubes under industrially relevant conditions

Becker

Xia

Tessonnier

et al. 2011

Carbon

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“…Two main results were achieved in the time dependent studies; first one is that the increase in the yield of CNF formation during the 20 min interval of CVD formation and from that point forward the formation rate does not change, second one is that there is stability in terms of product yield at this temperature which showed in the rage of 40% to 100%. Actually the yield of the CNF/CNT deposition for Zn tartrate found was comparable to the well-known catalysts such as Fe and Co (24,25). Thus this is another decision on Zn as an effective catalyst for CNF/CNT formation through CVD.…”

Section: Resultsmentioning

confidence: 83%

Carbon Nanotube and Nanofiber Growth on Zn-Based Catalysts

Dumanlı

Yürüm

2011

Fullerenes, Nanotubes and Carbon Nanostructures

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In this study, acetylene gas was delivered to a catalyst network consists of NaCl-support and Zn nanoparticles in a temperature range of 500-700°C by means of a chemical vapor deposition (CVD). A principle feature that delineated this CVD study from prior studies lay, first in the method used to support the catalyst and secondly the choice of the catalyst metal. In particular, NaCl was deliberately retained and exploited in subsequent manipulations for the reason that it performed remarkably well as a support medium. The catalytic activity of Zn towards production of CNT/CNFs appeared to be promoted as a result of using molten ionic substrate.

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“…Nevertheless, the ubiquitous horizontal fixed bed, favoured for its low cost and simplicity, is a major bottleneck in high throughput experimental work because it is labour intensive and the unnecessarily large reactor volumes used result in slow heating and cooling and yield location specific product [2]. Increasing throughput in fixed bed is difficult as experiments cannot be run in series due to the effects of the upstream reactions [3], and increasing parallel throughput [4] enlarges reactor volume and introduces homogeneous gas distribution problems. Finally, traditional fixed beds provide very little real-time growth data.…”

Section: Introductionmentioning

confidence: 99%