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Density Functional Study on Adsorption of NH<sub>3</sub> and NO<sub>x</sub> on the γ-Fe<sub>2</sub>O<sub>3</sub> (111) Surface
oleh: Wei Huang, Liang Wang, Lu Dong, Hongyun Hu, Dongdong Ren
Format: | Article |
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Diterbitkan: | MDPI AG 2023-03-01 |
Deskripsi
γ-Fe<sub>2</sub>O<sub>3</sub> is considered to be a promising catalyst for the selective catalytic reduction (SCR) of nitrogen oxide (NO<sub>x</sub>). In this study, first-principle calculations based on the density function theory (DFT) were utilized to explore the adsorption mechanism of NH<sub>3</sub>, NO, and other molecules on γ-Fe<sub>2</sub>O<sub>3</sub>, which is identified as a crucial step in the SCR process to eliminate NO<sub>x</sub> from coal-fired flue gas. The adsorption characteristics of reactants (NH<sub>3</sub> and NO<sub>x</sub>) and products (N<sub>2</sub> and H<sub>2</sub>O) at different active sites of the γ-Fe<sub>2</sub>O<sub>3</sub> (111) surface were investigated. The results show that the NH<sub>3</sub> was preferably adsorbed on the octahedral Fe site, with the N atom bonding to the octahedral Fe site. Both octahedral and tetrahedral Fe atoms were likely involved in bonding with the N and O atoms during the NO adsorption. The NO tended to be adsorbed on the tetrahedral Fe site though the combination of the N atom and the Fe site. Meanwhile, the simultaneous bonding of N and O atoms with surface sites made the adsorption more stable than that of single atom bonding. The γ-Fe<sub>2</sub>O<sub>3</sub> (111) surface exhibited a low adsorption energy for N<sub>2</sub> and H<sub>2</sub>O, suggesting that they could be adsorbed onto the surface but were readily desorbed, thus facilitating the SCR reaction. This work is conducive to reveal the reaction mechanism of SCR on γ-Fe<sub>2</sub>O<sub>3</sub> and contributes to the development of low-temperature iron-based SCR catalysts.