Time-resolved characterization of non-thermal plasma-assisted photocatalytic removal of nitric oxide

We performed time-resolved characterization of plasma-photocatalytic removal of nitric oxide (NO) in a ceramic foam packing double dielectric barrier discharge reactor using mid-infrared laser absorption spectroscopy. Non-thermal plasma (NTP) was generated in the porous ceramic foam coated with mesoporous TiO₂ thin film. Real-time NO monitoring was performed using a quantum cascade laser at 5.26 µm combined with a custom-designed multipass gas cell, leading to a sub-ppm detection limit at 0.1 s measurement time. By analyzing the feed gas of 90 ppm NO/1% O₂ balanced in N₂, the plasma treatment without TiO₂ photocatalyst had no effect on NO removal when the discharge power was below 45 W. In comparison, the NTP-TiO₂ system achieved an efficiency of 49% for NO removal even at the relatively low discharge power of 18 W. The synergy between NTP and TiO₂ photocatalyst effectively promotes the NO removal at low plasma discharge powers. However, we also observed a negative effect of TiO₂ photocatalyst on NO removal at a relatively high discharge power of 135 W. Copyright © 2019 IOP Publishing Ltd.