NH3 regeneration of SO2-captured V2O5/AC catalyst-sorbent for simultaneous SO2 and NO removal

Activated coke (AC) supported V2O5 (V2O5/AC) is an efficient catalyst-sorbent for simultaneous SO2 and NO removal from flue gas at 150–200°C. It was found that this type of catalyst-sorbent can be effectively regenerated in the presence of NH3 at temperatures much lower than required by AC under an inert atmosphere. Systematic experiments were performed in this study to understand the effect of regeneration conditions on SO2 and NO removal activities in the subsequent cycles, including regeneration temperature (200–380°C), NH3 concentration (0–5%), and regeneration time (10–80 min). Results indicate that the optimal regeneration conditions of SO2-captured V2O5/AC are: 300°C, 3–5 % NH3 in an inert atmosphere, 60 min. With the aid of elemental analysis and FT-IR characterization, it was found that the regeneration serves three roles: desorption of the adsorbed sulfur species from the catalyst-sorbent, surface modification by NH3, and adsorption (storage) of NH3 on the surface. The roles of NH3 are mainly in surface modification (chemical effect) and storage of NH3 on the surface (physical effect). The former occurs at relatively higher temperatures and favors SO2 removal and the latter is more significant at lower temperatures and favors NO removal.