Metal鈥揚orphyrin: A Potential Catalyst for Direct Decomposition of N2O by Theoretical Reaction Mechanism Investigation

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• 作者：Phornphimon Maitarad ; Supawadee Namuangruk ; Dengsong Zhang ; Liyi Shi ; Hongrui Li ; Lei Huang ; Bundet Boekfa ; Masahiro Ehara
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 17, 2014
• 年：2014
• 卷：48
• 期：12
• 页码：7101-7110
• 全文大小：546K
• 年卷期：v.48,no.12(June 17, 2014)
• ISSN：1520-5851

文摘

The adsorption of nitrous oxide (N₂O) on metal鈥損orphyrins (metal: Ti, Cr, Fe, Co, Ni, Cu, or Zn) has been theoretically investigated using density functional theory with the M06L functional to explore their use as potential catalysts for the direct decomposition of N₂O. Among these metal鈥損orphyrins, Ti鈥損orphyrin is the most active for N₂O adsorption in the triplet ground state with the strongest adsorption energy (鈭?3.32 kcal/mol). Ti鈥損orphyrin was then assessed for the direct decomposition of N₂O. For the overall reaction mechanism of three N₂O molecules on Ti鈥損orphyrin, two plausible catalytic cycles are proposed. Cycle 1 involves the consecutive decomposition of the first two N₂O molecules, while cycle 2 is the decomposition of the third N₂O molecule. For cycle 1, the activation energies of the first and second N₂O decompositions are computed to be 3.77 and 49.99 kcal/mol, respectively. The activation energy for the third N₂O decomposition in cycle 2 is 47.79 kcal/mol, which is slightly lower than that of the second activation energy of the first cycle. O₂ molecules are released in cycles 1 and 2 as the products of the reaction, which requires endothermic energies of 102.96 and 3.63 kcal/mol, respectively. Therefore, the O₂ desorption is mainly released in catalytic cycle 2 of a TiO₃鈥損orphyrin intermediate catalyst. In conclusion, regarding the O₂ desorption step for the direct decomposition of N₂O, the findings would be very useful to guide the search for potential N₂O decomposition catalysts in new directions.