Synthesis of single-walled carbon nanotubes in rich hydrogen/air flames

Zhang, Cen; Tian, Bo; Chong, Cheng Tung; Ding, Boning; Fan, Luming; Chang, Xiaofeng; Hochgreb, Simone

doi:10.1016/j.matchemphys.2020.123479

Cited by 17 publications

(18 citation statements)

References 34 publications

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“…As mentioned earlier, the abundance of oxygen assists in more heat release and creates a larger favorable environment for CNT production. Effect of abundance of high temperature region on improved yield and qualities of CNT has been observed by previous flame synthesis study by Zhang et al, [17]. Nonetheless, too much excess of oxygen is assumed to consume the potential carbon source or deactivate the catalyst particles and reduces CNT production.…”

Section: Effects Of Flame Structure On Cnt Growth Region At Varying Oxidizer Concentrationmentioning

confidence: 80%

“…A previous study pointed out that an increase in oxygen concentration provides more combustion and thus larger high temperature region [11]. In relation to this, Zhang et al, [17] mentioned that availability of abundant high temperature within the flame results in CNT with better quality and improved yield. However, a recent study demonstrated that there exists a limit to the oxygen concentration where too high of oxygen concentration can result in reduced CNT yield and growth rate [18].…”

Section: Introductionmentioning

confidence: 97%

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The Influences of Oxygen Concentration and External Heating on Carbon Nanotube Growth in Diffusion Flame

Zainal

Yasin

et al. 2021

CFDL

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Tight control of the carbon nanotube (CNT) synthesis process in flames remains a challenge due to the highly non-uniform gradient of flame thermochemical properties. The present study aims to establish a baseline model for flame-enhanced chemical vapor deposition (FECVD) synthesis of CNT and to analyze the CNT growth region at varying flame and furnace conditions. The numerical model comprises a computational fluid dynamics (CFD) simulation that is coupled with the CNT growth rate model to simulate the flow field within the furnace and the CNT growth respectively. Validation of the flame shape, flame length, and temperature profile are carried with a reasonable comparison to experimental measurements. A parametric study on the effects of furnace heating capacity and oxidizer concentration is conducted. The results of the CNT growth rate model reveal that there is a positive correlation between the heater power and CNT length. Supplying a higher concentration oxidizer at a fixed furnace power is predicted to result in further improvement in CNT length and high yield region. Flame structure analysis showed that with the heater turned on at 750 W (corresponding to heat flux of 21,713W/m2), the growth region expands twofold when oxygen concentration is increased from 19% to 24%. However, the growth region shrinks when the oxygen concentration is further increased to 27% which indicates depletion of carbon source for CNT growth due to excess oxygen. The finding of this research could guide and optimize the experiment of the flame-assisted CNT production in the future.

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Section: Effects Of Flame Structure On Cnt Growth Region At Varying Oxidizer Concentrationmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 97%

The Influences of Oxygen Concentration and External Heating on Carbon Nanotube Growth in Diffusion Flame

Zainal

Yasin

et al. 2021

CFDL

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“…[ 22 ]). For carbon nanomaterials, the most conventional method is chemical vapor deposition (CVD) [ 3 , 4 , 24 , 25 , 26 ], although there are other methods such as arc discharge and laser ablation [ 3 , 4 , 25 , 26 ]. Metal-oxide nanoparticles, including TiO 2 , SiO 2 , Fe x O y , and Al x O y , can be produced using the Stöber method [ 14 ] and precipitation [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

Flame Synthesis of Carbon and Metal-Oxide Nanoparticles: Flame Types, Effects of Combustion Parameters on Properties and Measurement Methods

et al. 2023

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Carbon and metal-oxide nanoparticles (NP) are currently synthesized worldwide for various applications in the solar-energy, optical, pharmaceutical, and biomedical industries, among many others. Gas phase methods comprise flame synthesis and flame spray pyrolysis (FSP), which provide high efficiency, low cost, and the possibility of large-scale applications. The variation of combustion operation parameters exerts significant effects on the properties of the NPs. An analysis of the latest research results relevant to NP flame synthesis can provide new insight into the optimization of these methods and the development of these techniques for a large scale. This review offers insight into the current status of flame synthesis for carbon and metal-oxide NPs—specifically containing analysis and comparison of the most common carbon and metal-oxide NP production techniques. The burner configurations used at the laboratory scale and large scale are also discussed, followed by the assessment of the influence of combustion parameters on the properties of NPs. Finally, the features of the measurement techniques applied for determining NP properties were described.

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“…In another study, a premixed flat flame was utilized by Zhang et al [10] to synthesize single-walled CNT (SWCNT) in rich hydrogen/air combustion with a ferrocene catalyst.…”

Section: Introductionmentioning

confidence: 99%

The Control on Morphology and Crystallinity of CNT in Flame Synthesis with One-Dimensional Reaction Zone

Ibrahim¹,

Hamzah²,

Yasin³

et al. 2023

Preprint

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The growth of carbon nanotubes (CNT) in flame requires imperative conditions that are difficult to achieve in a highly heterogeneous environment. Therefore, the analysis of the properties of the reaction zone within the flame is critical for the optimal growth of CNT. In the present study, a comprehensive comparison between the CNT synthesis using methane diffusion flame and that of premixed flame is conducted regarding the morphology and crystallinity of the as-grown nanotubes. The premixed burner configuration created a flame that isstabilized across axisymmetric stagnation flow through sintered metal, making the flame one-dimensional in nature as opposed to the co-flow configuration of diffusion flame. The significant difference in temperature distribution between the two flames causes the difference in the characteristic pattern of the growth products. In diffusion flame, the growth is limited to specific regions at certain height-above-burners (HAB) with suitable thermochemical conditions. The identified growth regions at different HAB showed similar temperature distribution that produces CNT of similar characteristics. In contrast with premixed flame, the growth of CNT dictates by only the HAB due to relatively uniform temperature distribution along the radial directions but significantly different in the vertical direction.

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Synthesis of single-walled carbon nanotubes in rich hydrogen/air flames

Cited by 17 publications

References 34 publications

The Influences of Oxygen Concentration and External Heating on Carbon Nanotube Growth in Diffusion Flame

The Influences of Oxygen Concentration and External Heating on Carbon Nanotube Growth in Diffusion Flame

Flame Synthesis of Carbon and Metal-Oxide Nanoparticles: Flame Types, Effects of Combustion Parameters on Properties and Measurement Methods

The Control on Morphology and Crystallinity of CNT in Flame Synthesis with One-Dimensional Reaction Zone

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