Dissociation of vibrationally excited methane on Ni catalyst Part 1. Application to methane steam reforming

This paper describes extensive experimental research on steam reforming of methane using barrier discharges with/without Ni/SiO2 catalyst. Nickel catalyst clearly showed chemical activity at 400 °C in the presence of barrier discharge. Methane conversion largely exceeded over equilibrium conversion rate, whereas product selectivity tended to follow equilibrium composition at given temperature: energy cost and energy efficiency achieved 134 MJ/kg H2 and 69%, respectively. Electric property was unchanged in the presence of nickel catalyst, but at least 400 °C must be maintained in order to derive synergistic effect between barrier discharge and Ni/SiO2 catalyst. Methane activation mechanism is also discussed based on numerical simulation on streamer propagation in pure methane. Vibrationally excited methane is most abundant (1016 cm^-3 at 300 K, 101.3 kPa) and long-lived (~1 (mu)s) radical species produced by electron impact, and those vibrational species seemed to improve dissociative chemisorption on nickel surface at low temperature, leading to remarkable process improvement.