Effect of fuel and oxygen concentration toward catalyst encapsulation in water-assisted flame synthesis of carbon nanotubes

Hamzah, Norikhwan; Yasin, Mohd Fairus Mohd; Yusop, Mohd Zamri Mohd; Haniff, Muhammad Aniq Shazni Mohammad; Hasan, Mohd Faizal; Tamrin, Khairul Fikri; Subha, Nurul Adilla Mohd

doi:10.1016/j.combustflame.2020.07.007

Cited by 11 publications

(20 citation statements)

References 52 publications

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“…This provides higher surface area with favourable temperature conditions in promoting the growth of CNTs. [2,7,13]. There exists preferential catalytic reactivity of CO towards Fe catalyst particles [15] and of C2H2 towards Ni catalyst particles [1].…”

Section: Application Of Chimneymentioning

confidence: 99%

“…Optimum conditions for growing CNTs were characterised on each burner configuration with different type of metal catalyst and hydrocarbon fuel [2][3][4]. Based on initial characterisation established on the optimum condition in growing CNTs on each type of burner, recent developments on flame synthesis have expanded towards optimisation of burner designs in order to improve yields and qualities of CNTs such as development of flame assisted chemical vapour deposition hybrid burner [5], improvement on reactant gas tube position on premixed flame [6], application of water [7] and sulphur as additives [5]. Despite recent optimisations on burner designs, high temperature environment in flame synthesis limits the application of synthesizing CNTs on low melting temperature metal substrate.…”

Section: Introductionmentioning

confidence: 99%

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Chemical kinetics modelling for the effect of chimney on diffusion flame in carbon nanotubes synthesis

Wong

How

2022

J. Phys.: Conf. Ser.

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Hydrocarbon flame syntheses of carbon nanotubes (CNTs) on various metals substrates have been reported in literature, but existing methods are limited to usage of high melting temperature metals substrate due to excessive temperature in conventional diffusion flame burner. To address this limitation, high thermal conductivity chimney is innovatively incorporated into the diffusion burner to control flame temperature. Hence, the aim of this study is to investigate the effect of chimney application on the interaction behaviour between flame temperature profile and concentration of post combustion species distribution of diffusion flame. In this study, Computational Fluids Dynamics (CFD) – Chemical Kinetics (Chemkin) coupling method is used to simulate the flow and transport behaviour of laminar methane-air mixture in combustion environment. Kinetics mechanism is imported into species transport model of Chemkin simulator to further determine the reaction between combustion species and temperature profile of the mixture. Heat transfer models are then integrated into simulation to investigate the cooling effect of chimney during the combustion of methane-air mixture. This numerical simulation study provides insights on effects of chimney application towards cooling, species concentration, flame temperature and paving path for controlling the growth of CNT on low melting temperature metal substrate. Numerical models show improvement in temperature controls, increase in gas species concentration and in surface area that is favourable for growth of CNTs.

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Section: Application Of Chimneymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical kinetics modelling for the effect of chimney on diffusion flame in carbon nanotubes synthesis

Wong

How

2022

J. Phys.: Conf. Ser.

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“…Figure 10 shows the physical-based and the mixture fraction-based flame structures for the flame under a wire mesh at 12.5 mm HAB with varying oxidizer concentrations. Although the published work by Hamzah et al, [15] analyzed a wide range of growth locations from 6 mm to 17 mm HAB, the present study focuses on 12.5 mm HAB with different oxidizers to study the effects of oxygen concentration on CNT growth region. When the oxygen concentration increases from 21% to 27%, the stoichiometric mixture fraction of these four flames increases from 0.05 up to 0.0691 as shown in Table 2.…”

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

confidence: 99%

“…One of the control parameters in diffusion flame synthesis is the inlet oxygen concentration. Previous flame synthesis experiments showed that an increase in inlet oxygen concentration improves CNT growth [15,16]. A previous study pointed out that an increase in oxygen concentration provides more combustion and thus larger high temperature region [11].…”

Section: Introductionmentioning

confidence: 98%

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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“…Many research groups are conducting intensive research on the synthesis of carbon nanotubes (CNTs) [1,2] and fullerenes [3,4] in flames. The authors of [5] studied the formation of fullerenes in a laminar premixed toluene-oxygen flame depending on the pressure in the system, the C/O ratio of the combustible mixture, and the rate of its supply.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Nanomaterials in a Coaxial Flame

Lesbayev¹

2020

Eurasian Chem. Tech. J.

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The paper presents the results of experimental studies of the synthesis of fullerenes C60 in a coaxial flame of benzene and acetylene at low pressures; of the synthesis of graphene in a coaxial flame of ethanol and propane, benzene, and acetylene; of the soot formation process in the coaxial flame of propane and ethanol. It has been established that the optimum temperature of a coaxial flame for the formation of fullerenes C60 is 970‒1000 °C with the carbon to oxygen ratio in the internal benzene-oxygen flame C/O ≈ 0.9 ÷ 1. The C/O ratio in an external acetylene-oxygen flame was maintained at a stoichiometric ratio. It was found that the preliminary (before feeding into the burner) treatment of the benzene-oxygen mixture using ultraviolet (UV) radiation with a wavelength of 254 nm promotes an increase in the yield of fullerenes. The synthesis conditions were optimized for: 5‒10 layers graphene in a coaxial flame of acetylene and ethanol; graphene containing more than 10 layers in a coaxial flame of propane and ethanol; one and two-layer graphene in a coaxial flame of ethanol and benzene. The possibility of a significant reduction of the formation of soot particles in the diffusion flame of propane by organizing its coaxial combustion with ethanol is shown.

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Effect of fuel and oxygen concentration toward catalyst encapsulation in water-assisted flame synthesis of carbon nanotubes

Cited by 11 publications

References 52 publications

Chemical kinetics modelling for the effect of chimney on diffusion flame in carbon nanotubes synthesis

Chemical kinetics modelling for the effect of chimney on diffusion flame in carbon nanotubes synthesis

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

Synthesis of Nanomaterials in a Coaxial Flame

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