Author(s)

Katsuya Konno, Kaoru Onoe, Yasuyuki Takiguchi, Tatsuaki Yamaguchi

Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, Chiba, Japan.
Hitachi Automotive Systems Ltd., Automotive Systems R&D Laboratory, Kawasaki, Japan.

Methane was decomposed to hydrogen and carbon nanotubes (CNTs) by microwave plasma, using Fe/Si catalyst activated by biased (—150 V) hydrogen plasma for various treatment times. Upon exposure to biased hydrogen plasma, the catalyst surface becomes lumpy within 1 min, coheres between 5 and 10 min and forms particles after 20 min. The methane conversion increased up to 93% over the treatment time of 5 min. The hydrogen yield showed as similar tendency as the methane conversion and kept 83% at treatment time of 5 min. The treatment time up to 1 min increased the amount of deposited carbon, and after treatment time of 5 min it dropped; then again after treatment time of 20 min, it increased to reach a maximum value of 22 g_c/g_cat. Deposited carbon was found to be consisted of carbon nanotubes. It grew vertically on the catalyst surface and reached a maximum length of 30.7 nm after treatment time of 10 min. Multiple types of CNTs were present, and the CNT diameters decreased with increasing plasma treatment time.

Hydrogen; Methane Decomposition; Carbon Nanotubes; Microwave Plasma; Methane; H2 Plasma Treatment

K. Konno, K. Onoe, Y. Takiguchi and T. Yamaguchi, "Direct Preparation of Hydrogen and Carbon Nanotubes by Microwave Plasma Decomposition of Methane over Fe/Si Activated by Biased Hydrogen Plasma," Green and Sustainable Chemistry, Vol. 3 No. 1, 2013, pp. 19-25. doi: 10.4236/gsc.2013.31004.