Search

To study the production mechanism of atomic nitrogen, the temporal profile and spatial distribution of atomic nitrogen are measured in atmospheric pressure pulsed positive corona discharge using two-photon absorption laser-induced fluorescence. The absolute atomic nitrogen density in the streamer filaments is estimated from decay rate of atomic nitrogen in N2 discharge. The results indicate that the absolute atomic nitrogen density is approximately constant against discharge energy. When the discharge voltage is 21.5 kV, production yield of atomic nitrogen produced by an N2 discharge pulse is estimated to be 2.9 - 9.8 × 1013 atoms and the energy efficiency of atomic nitrogen production is estimated to be about 1.8 - 6.1 × 1016 atoms/J. The energy efficiency of atomic nitrogen production in N2 discharge is constant against the discharge energy, while that in N2/O2 discharge increases with discharge energy. In the N2/O2 discharge, two-step process of N2 dissociation plays significant role for atomic nitrogen production. [ABSTRACT FROM AUTHOR]

Low temperature catalytic reactions induced by nonthermal plasma (NTP) have been of great interest in plasma chemistry for application to pollution control and energy-related issues. Current progress in the experimental observations and the understanding of interactions between NTP and catalyst are reviewed herein. Considering the diffusion length and lifetime of reactive species, we introduced a dimensionless parameter Λ that describes the criteria for a direct interaction between NTP and catalysts. Several lines of experimental evidences on the interaction were introduced: discharge mode, formation of metal cluster ions, and plasma-induced fluorescence from the catalyst. For faujasite zeolites, the Si/Al ratio was found to be an important parameter that determines the propagation of surface streamers and catalytic performance. The oxidation status of metals is closely correlated with the Si/Al ratio, which is related to substantial changes in electrical resistivity. [ABSTRACT FROM AUTHOR]

The effect of catalyst types on optical emission was studied in N2 discharge under atmospheric pressure. In silver nanoparticle-loaded MS-13X and HY, purple emissions were observed. On the other hand, green emission was observed in silver nanoparticle-loaded HY. This spectrum had a broadband around 540±60 nm. It may be fluorescence from excited silver on catalyst surface. When toluene adsorbed onto Ag/HY, emission color changed from green to purple in adsorption area only. After catalyst regeneration by O2 plasma treatment, the emission color returned to green. There, interesting phenomena were important to figure out the mechanism of plasma-catalyst hybrid technology. [ABSTRACT FROM PUBLISHER]