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Abstract: Catalysts used in nonthermal plasma (NTP)-catalytic removal of volatile organic com-
pounds are often deactivated by coke deposits. Their regeneration and subsequent repeti-
tive use are therefore essential for maintaining process efficiency and reducing operating
costs. This work investigates the potential of NTP regeneration and repetitive use of coke-
deactivated catalysts. Packed-bed dielectric barrier discharge reactors filled with TiO2 and
Pt/γ-Al2O3 pellets were used for toluene removal in atmospheric air. The catalysts de-
activated during toluene decomposition were regenerated by NTP in oxygen to promote
coke oxidation. This removal-deactivation-regeneration cycle was repeated 3 times. Two
NTP regeneration strategies were studied: continuous plasma regeneration and sequential
plasma regeneration, the latter combining shorter NTP exposures with pellet mixing. In
addition, catalyst pre-treatment by NTP in oxygen was also performed before toluene re-
moval. Reactor temperature and current waveforms were continuously monitored through-
out the experiments. Toluene removal efficiency (TRE), energy cost, and production of
gaseous products (CO2, CO, HCOOH) were evaluated by Fourier-transform infrared ab-
sorption spectroscopy. The surface of catalytic pellets was analyzed by scanning electron
microscopy coupled with energy-dispersive spectroscopy. The results revealed a strongly
catalyst-dependent response to both NTP regeneration and pre-treatment. TiO2 exhibited
higher or comparable TRE after regeneration in repeated cycles of its use than fresh and
non-regenerated catalysts, and its performance was further enhanced by the pre-treatment.
In contrast, although the regeneration increased the TRE of Pt/γ-Al2O3 compared to the
non-regenerated catalyst, its efficiency in repeated cycles remained lower than that of the
fresh catalyst. Moreover, pre-treatment of Pt/γ-Al2O3 further reduced its TRE.
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