Nonthermal Plasma Regeneration of Coke-Deactivated Catalysts Used for Plasma-Catalytic VOC Removal

Abstract

The research was focused on oxygen nonthermal plasma regeneration of coke-deactivated catalysts used for plasma-catalytic toluene removal from air. The nonthermal plasma was generated in a packed-bed dielectric barrier discharge reactor at atmospheric pressure using pellet-shaped catalysts (TiO₂, γ-Al₂O₃, Pt/γ-Al₂O₃, Pd/γ-Al₂O₃). Gaseous products of experiments were continuously analyzed by infrared spectroscopy. Plasma regeneration was compared with ozone and thermal regeneration. The results indicated that the plasma regeneration exhibited the highest coke removal efficiency; however, the regeneration was spatially non-uniform, as confirmed by SEM and TGA. The effect of ozone and heat (100°C) was negligible. GC–MS analysis revealed that coke composed of long-chain alkanes and oxygen- or nitrogen-substituted aromatics was significantly reduced after plasma regeneration, unlike other regeneration techniques.