Methane steam reforming for producing hydrogen in an atmospheric-pressure microwave plasma reactor

A methane steam reforming process for producing mainly hydrogen in an atmospheric-pressure microwave plasma reactor is demonstrated. Nano carbon powders, CO_x, C₂H₂, C₂H₄, and HCN were also formed. Intermediates such as OH, NH, CH, and active N₂ were identified using optical emission spectroscopy. The selectivity of H₂ was greater than 92.7% at inlet H₂O/CH₄ molar ratio (R) ≧ 0.5, and was higher than that obtained using methane plasmalysis because steam inhibited the formation of C₂H₂. The highest methane conversion was obtained at R = 1, reaching 91.6%, with the lowest specific energy consumption of H₂ formation at [CH₄]_in = 5%, 1.0 kW, and 12 slpm. The plasma-assisted catalysis process, which packed Ni/Al₂O₃ catalysts in the discharge zone and supplied heat using hot effluents, was used to elevate the methane conversion and hydrogen selectivity. However, large amounts of 40–70 nm carbon powder, which is electrically conductive, were produced, resulting in rapid catalyst deactivation due to carbon being deposited on the surface and in the pores of catalysts.     

Growth and characteristics of metal-containing diamond-like carbon using a self-assembled process

A recently developed self-assembled method, involving the use of a single metal target and a fixed substrate in a sputter deposition chamber, was used for the growth of various metal-containing diamond-like carbon thin films. The metals used include, Cu, Pt, and Ni. The resulting films consist of self-assembled alternating dark and bright layers, both of which constitute a period. The dark layer was found to always have a higher metal concentration than the bright layer in a period. Effects of the growth condition on the growth rate, periodicity, and film structure were examined. The relation between the growth condition and the film characteristics is discussed.