Recyclable Iron Reduction Denitration: A Strategy for Removal of Nitrogen Oxides

An innovative recyclable denitration strategy was proposed, where Fe-based oxygen carriers (OCs) with various oxidation states act as the agent reducing NO into N-2. Herein, the detailed redox properties of OCs were exploited to reveal the possibility and characteristic of the recyclable iron reduction denitration processes. Fe2O3 supported on Al2O3 was first prepared, and the lattice oxygen migration ability of the prepared OCs was detected. Then, the OCs were reduced by CO to obtain the low-valence iron oxides/iron (Fe (x) O (y) /Fe) to reduce NO into N-2 under the presence and absence of reducing gas, various reduction degrees, and different temperatures. Results showed that the NO removal efficiency improves with a deeper reduction degree of the OCs and higher reaction temperature (800 C-degrees). In addition, Fe2O3(104)/Al2O3 with high Miller index prepared by the coprecipitation method exhibits higher NO removal efficiency than Fe2O3/Al2O3 produced by the impregnation method since Fe2O3(104)/Al2O3 shows larger specific surface area, more porous structures, and dangling bonds. Compared with the method of spraying iron powder in the furnace for denitration, recyclable iron reduction denitration is more economical and environmentally friendly.