γ-Al2O3(110) 在 NO + H2 反应中的催化活性：DFT 研究,Physical Chemistry Chemical Physics

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γ-Al2O3(110) 在 NO + H2 反应中的催化活性：DFT 研究
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2023-08-25 , DOI: 10.1039/d3cp02909c
Alexander Cholach ₁

Affiliation

本工作利用密度泛函理论计算研究了γ-Al ₂ O ₃ (110)表面与NO和H _{2的相互作用。}游离的γ-Al ₂ O ₃ (110)吸附NO并结合H原子，但排斥H ₂分子。低配位 O ^II –Al ^III –O ^{II原子的三重态提供了 γ-Al}₂ O ₃ (110) 沿以下路径的催化活性：(i) NO/Al ^III的吸附随后是 H 的结合₂通过中间体NO/Al ^III + 2×H/O ^II络合物形成羟胺衍生物NHOH；(ii) NHOH重组并通过中间体NHOH/Al ^III + NHOH/Al ^IV释放N ₂或吸附NO然后通过中间体NHOH/Al ^III + NO/Al ^IV释放N ₂ O ；_{该途径以γ-Al 2} O ₃ (110)的再生结束。计算出的吸附热确保 H 原子从沉积的 Pt 扩散到表面 (110)，引发 NH ₂ /Al ^III + H/O ^II络合物的形成，该络合物吸热释放 NH ₃并且足够稳定以抑制阶段(ii)上述反应途径。NO + H ₂混合物中过量的O ₂排除H/Pt并消除抑制。氮氧化物的形成受到抑制，但并不能被更多放热的表面工艺所排除。揭示了本体和表面氮氧化物Al ₃₂ O ₄₇ N的N掺杂电导率以及H原子吸附热对带隙宽度的依赖性，这表明带隙宽度与催化活性之间的关系。

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Catalytic activity of γ-Al2O3(110) in the NO + H2 reaction: a DFT study

In this work, the interaction of the surface of γ-Al₂O₃(110) with NO and H₂ was studied using density functional theory calculations. Free γ-Al₂O₃(110) adsorbs NO and binds H atoms, but repels the H₂ molecule. A triplet of low-coordinated O^II–Al^III–O^II atoms provides the catalytic activity of γ-Al₂O₃(110) along the path: (i) the adsorption of NO/Al^III is followed by the binding of H₂ to form a hydroxylamine derivative NHOH through an intermediate NO/Al^III + 2 × H/O^II complex; (ii) recombination of NHOH with the release of N₂ through an intermediate NHOH/Al^III + NHOH/Al^IV or adsorption of NO followed by the release of N₂O through the intermediate NHOH/Al^III + NO/Al^IV; the pathway ends with the regeneration of γ-Al₂O₃(110). The calculated adsorption heats ensure the diffusion of H atoms from the deposited Pt to the surface (110), initiating the formation of the NH₂/Al^III + H/O^II complex, which releases NH₃ endothermically and is stable enough to inhibit stage (ii) of the above reaction pathway. An excess of O₂ in the NO + H₂ mixture excludes H/Pt and eliminates inhibition. The formation of oxynitrides is suppressed, but not excluded by more exothermic surface processes. The N-doped conductivity of bulk and surface oxynitrides Al₃₂O₄₇N and the dependence of the heat of adsorption of H atoms on the band gap width were revealed, which suggests a relationship between the band gap width and catalytic activity.

更新日期：2023-08-25

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