Experimental Study And Mechanism Interpretation Of Fe₂O₃-catalyzed N₂O Decomposition In Fluidized Bed

N2O is a kind of greenhouse gas, which has a strong destruction effect on the ozonosphere in aerosphere. Nitrogen oxides and SO2 emission can be controlled by fluidized bed combustion technology, but its N2O emission concentration is 30～ 360mg/Nm3, which is times higher than that in pulverized power plant (less than 30mg/Nm3). Therefore, it is necessary to further study the mechanism of N2O formation and find effective measure to prohibit its generation.In this paper, a highly active catalyst with low cost was prepared to reduce N2O emissions, which also avoided secondary pollution. Active ingredient with optimum catalytic activity was selected to prepare Fe2O3/Al2O3 metal oxide catalyst with Al2O3 as carrier by co-precipitation method. The effects of different preparation conditions on the catalytic activity was examined in a small fluidized bed, in order to pick out the best catalyst with the highest activity, characterization work was accomplished. The reasonable explanation was put forward to account for the reason why the catalytic activity would change.The mechanism of the catalytic decomposition of N2O over the prepared catalyst was explored, with all calculationsperformed based on density functional theory (DFT) approach and DMol3 package of Material Studio 5.0. Structural optimization was fulfilled by the generalized gradient approximation (GGA), PBE being selected as the density functional form. The results showed that in the active site of the catalyst surface N2O molecules decomposed through two step reaction and eventually into O2 and N2. Firstly, N2O was adsorbed on the active site to gain energy and its chemical bond was cleaved to generate an oxygen atom and a N2 molecule. Finally, the oxygen atom was adsorbed on the surface and reacted with another N2O molecule to produce a molecule of O2 and N2. The first reaction energy barrier of the N2O at iron and oxygen sites was 0.300 eV and 2.069eV, and the second energy barrier was 2.672eV and 2.649eV.Reaction potential energy surface indicated that Fe2O3/Al2O3 catalyst has a high chemical activity to decompose N2O, confirming the reasonableness of the reaction mechanism analysis.