Filamentous Carbon Formation and Gasification: Thermodynamics, Driving Force, Nucleation, and Steady-State Growth

Snoeck, Joost-Willem; Froment, Gilbert F.; Fowles, Martin

doi:10.1006/jcat.1997.1634

Cited by 377 publications

(235 citation statements)

References 32 publications

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“…Two models were considered for pyrolytic carbon (Zheng et al 2013): a deposition droplet model proposed by Shi et al (1997) and the combined mechanism of nucleation on graphene and of carbon growth at the edge of graphene (Hu and Hüttinger 2002). Several carbon containing intermediate species were detected during methane decomposition at catalyst surfaces, and associated mechanisms of filamentous deposit growth were proposed , Snoeck et al 1997a, Wagg et al 2005.…”

Section: Carbon Depositsmentioning

confidence: 99%

On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes

Jaworski

Zakrzewska

Pianko‐Oprych

2017

Reviews in Chemical Engineering

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AbstractExtensive literature information on experimental thermodynamic data and theoretical analysis for depositing carbon in various crystallographic forms is examined, and a new three-phase diagram for carbon is proposed. The published methods of quantitative description of gas-solid carbon equilibrium conditions are critically evaluated for filamentous carbon. The standard chemical potential values are accepted only for purified single-walled and multi-walled carbon nanotubes (CNT). Series of C-H-O ternary diagrams are constructed with plots of boundary lines for carbon deposition either as graphite or nanotubes. The lines are computed for nine temperature levels from 200°C to 1000°C and for the total pressure of 1 bar and 10 bar. The diagram for graphite and 1 bar fully conforms to that in (Sasaki K, Teraoka Y. Equilibria in fuel cell gases II. The C-H-O ternary diagrams. J Electrochem Soc 2003b, 150: A885–A888). Allowing for CNTs in carbon deposition leads to significant lowering of the critical carbon content in the reformates in temperatures from 500°C upward with maximum shifting up the deposition boundary O/C values by about 17% and 28%, respectively, at 1 and 10 bar.

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Section: Carbon Depositsmentioning

confidence: 99%

On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes

Jaworski

Zakrzewska

Pianko‐Oprych

2017

Reviews in Chemical Engineering

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“…Snoeck et al [48] suggest that the difference in formation of carbon fibres and CNTs is due to the different rate at which carbon deposition nucleates compared to the diffusion through the nickel catalyst. When carbon deposition occurs slower it is more likely to form fibres, whilst fast deposition form CNTs since deposition is fast compared to diffusion, meaning it only occurs around the particles edge, forming a tube.…”

Section: Effect Of Steam On Carbon Depositionmentioning

confidence: 99%

Control of steam input to the pyrolysis-gasification of waste plastics for improved production of hydrogen or carbon nanotubes

Acomb

2014

Applied Catalysis B: Environmental

158

102

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Carbon nanotubes (CNTs) have been proven to be possible as high-value by-products of hydrogen production from gasification of waste plastics. In this work, steam content in the gasification process was investigated to increase the quality of CNTs in terms of purity.Three different plastics -low density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) were studied in a two stage pyrolysis-gasification reactor. Plastics samples were pyrolysed in nitrogen at 600°C, before the evolved gases were passed to a second stage where steam was injected and the gases were reformed at 800°C in the presence of a nickelalumina catalyst. To investigate the effect that steam plays on CNT production, steam injection rates of 0, 0.25, 1.90 and 4.74 g h -1 were employed. The CNTs produced from all three plastics were multiwalled CNTs with diameters between 10 and 20 nm and several microns in length. For all the plastic samples, raising the steam injection rate led to increased hydrogen production as steam reforming and gasification of deposited carbon increased. High quality CNTs, as observed from TEM, TPO and Raman spectroscopy, were produced by controlling the steam injection rate. The largest yield for LDPE was obtained at 0 g h -1 steam injection rate, whilst PP and PS gave their largest yields at 0.25 g h -1 . Overall the largest CNT yield was obtained for PS at 0.25 g h -1 , with a conversion rate of plastic to CNTs of 32% wt.

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“…The percentage of Co(AC) 2 is closely related to the C/Co atomic ratio and to the size of the formed catalyst particles. Excessive Co(AC) 2 (for example, Co(AC) 2 /PA > 1/3) leads to the products dominant with large encapsulated cobalt particles other than nanotubes, likely due to the size increase of cobalt particles hindering the diffusion of carbon species within the particles, which was believed to be crucial in the catalytic growth of tubes [17]. Large catalyst particles may be responsible for the formation of the bamboo-shape tubes, as described below.…”

Section: Resultsmentioning

confidence: 99%

Formation of bamboo-shape carbon nanotubes by controlled rapid decomposition of picric acid

Lu¹,

Zhu²,

Su³

et al. 2004

Carbon

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In the presence of catalysts, carbon nanotubes (CNTs) can efficiently grow in the environment generated by the rapid decomposition of normal explosives. Controlling the reaction parameters of a mixture of picric acid (PA) with cobalt acetate and paraffin can lead to a welldefined morphology of CNTs. The formation of bamboo-shape tubes is favorable at relatively high Co(AC) 2 /PA and paraffin/PA ratios. It is found that the bamboo-shape tubes are different in morphology and structure and can be categorized roughly into two types, according to the participation of the catalyst nanoparticles. The formation of the two types is discussed.

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Filamentous Carbon Formation and Gasification: Thermodynamics, Driving Force, Nucleation, and Steady-State Growth

Cited by 377 publications

References 32 publications

On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes

On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes

Control of steam input to the pyrolysis-gasification of waste plastics for improved production of hydrogen or carbon nanotubes

Formation of bamboo-shape carbon nanotubes by controlled rapid decomposition of picric acid

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