2020 年 63 巻 12 号 p. 641-648
Plasma-assisted heterogeneous catalysis for CH4 conversion attracts keen attention because the strong C-H bond breaking is possible via vibrational excitation of CH4 at low temperature. Similarly, vibrational excitation of CO2 possesses unique reactivity in heterogeneous catalysis. This paper provides a kinetic analysis of nonthermal plasma-assisted CH4 dry reforming to elucidate the drastic reaction promotion mechanism. Lanthanum-modified Ni/Al2O3 catalyst was combined with dielectric barrier discharge at 5 kPa and 400–700℃. Activation energy decreases from 91.0 kJ/mol to 44.7 kJ/mol which was well correlated with the state-specific gas-surface reactivity of vibrationally excited CH4 on Ni surface. Reactivity of plasma-excited CO2 is discussed by the in situ DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) under the influence of CO2 plasma, showing the plasma-excited CO2 promotes the formation of surface carbonate species (CO32－) : co-operative activation of CO2 is the key to enhancing overall reforming performance.
