Enhanced Synthesis of Carbon Nanomaterials Using Acoustically Excited Methane Diffusion Flames

Materials

Shuhn-Shyurng Hou²  Kuan-Ming Chen²  Zong-Yun Yang²  Ta-Hui Lin¹ 

[1] Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan;Department of Mechanical Engineering, Kun Shan University, Tainan 71070, Taiwan; E-Mails:

关键词: flame synthesis;    carbon nanotubes;    carbon nano-onions;    acoustic excitation;   

DOI  :  10.3390/ma8084805

来源: mdpi

【 摘 要 】

Acoustically modulated methane jet diffusion flames were used to enhance carbon nanostructure synthesis. A catalytic nickel substrate was employed to collect the deposit materials at sampling position z = 10 mm above the burner exit. The fabrication of carbon nano-onions (CNOs) and carbon nanotubes (CNTs) was significantly enhanced by acoustic excitation at frequencies near the natural flickering frequency (ƒ = 20 Hz) and near the acoustically resonant frequency (ƒ = 90 Hz), respectively. At these characteristic frequencies, flow mixing was markedly enhanced by acoustic excitation, and a flame structure with a bright slender core flame was generated, which provided a favorable flame environment for the growth of carbon nanomaterials. The production rate of CNOs was high at 20 Hz (near the natural flickering frequency), at which the gas temperature was about 680 °C. Additionally, a quantity of CNTs was obtained at 70–95 Hz, near the acoustically resonant frequency, at which the gas temperature was between 665 and 830 °C. However, no carbon nanomaterials were synthesized at other frequencies. The enhanced synthesis of CNOs and CNTs is attributed to the strong mixing of the fuel and oxidizer due to the acoustic excitation at resonant frequencies.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.