Direct Conversion of Methane into Methanol and Formaldehyde in an RF Plasma Environment I: A Preliminary Study

Ya-Fen Wang; Cheng-Hsien Tsai; Minliang Shih; Lien-Te Hsieh; WenChing Chang

doi:10.4209/aaqr.2005.12.0006

Direct Conversion of Methane into Methanol and Formaldehyde in an RF Plasma Environment I: A Preliminary Study

Ya-Fen Wang ¹, Cheng-Hsien Tsai², Minliang Shih³, Lien-Te Hsieh⁴, WenChing Chang³

¹Department of Bioenvironmental Engineering, Chung Yuan Christian University, No. 200, Chung Pei Road, Chung-Li 320, Taiwan
²Department of Chemical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Chien Kung Road, Kaohsiung 807, Taiwan
³Department of Environmental Engineering and Science, Chia-Nan University of Pharmacy and Science, No. 60, Sec. 1, Erh-Jen Road, Tainan 717, Taiwan
⁴Department of Environmental Engineering and Science National Pingtung University of Science and Technology, 1 Hseuh Fu Rd., Nei Pu Hsiang, Ping Tung, 912, Taiwan

Received: November 1, 2005
Revised: November 1, 2005
Accepted: November 1, 2005
Download Citation: ||https://doi.org/10.4209/aaqr.2005.12.0006

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Cite this article:
Wang, Y.F., Tsai, C.H., Shih, M., Hsieh, L.T. and Chang, W. (2005). Direct Conversion of Methane into Methanol and Formaldehyde in an RF Plasma Environment I: A Preliminary Study. Aerosol Air Qual. Res. 5: 204-210. https://doi.org/10.4209/aaqr.2005.12.0006

ABSTRACT

The direct conversion of methane (CH₄) into methanol (CH₃OH) and HCHO in an Argon (Ar) 50W radio-frequency plasma system was applied and the effects of various feed compositions, CH₄/O₂ ratio, and plasma discharge areas were compared. Additionally, the effects of various methane to oxygen ratios and plasma discharge areas were studied. It was found that in an Ar stream, the CH₃OH conversion ratio in the CH₄/O₂ plasma system was higher than that in CH₄/CO, CO/H₂ and CH₄/H₂/O₂ plasma systems. The conversion of CH4 reached 19.1% at CH₄/O₂ = 40/60; the yield of CH3OH was 1.12% and 16.0% CO, the major product, was produced. A larger plasma discharge area, resulting in a longer residence time, corresponded to higher CH₄ conversion, but a lower CH₃OH conversion ratio, because of further decomposition into CO and CO₂. Interestingly, no carbon deposition was observed in the RF plasma system, and the carbon balance was between 0.94 and 1.19.