Molecular Mechanism of the Formic Acid Decomposition on V2O5/TiO2 Catalysts: A Periodic DFT Analysis

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• 作者：Vasilii I. Avdeev ; Valentin N. Parmon
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：November 10, 2011
• 年：2011
• 卷：115
• 期：44
• 页码：21755-21762
• 全文大小：1001K
• 年卷期：v.115,no.44(November 10, 2011)
• ISSN：1932-7455

文摘

Molecular and dissociative forms of formic acid adsorption on the V₂O₅/TiO₂ model surface, possible intermediates, and transition states along of the dehydrogenation (HCOOH 鈫?CO₂ + H₂) and dehydration (HCOOH 鈫?CO + H₂O) pathways have been studied by the periodic density functional theory. The CI-NEB analysis of the reaction pathways showed that two types of molecular adsorbed HCOOH species initiate two completely different reaction channels. The first more stable adsorbed form is transformed into the surface formates, which decompose according to the 鈥渇ormate mechanism鈥?to yield products of dehydrogenation, whereas the second weakly adsorbed molecular form decomposes, releasing CO and forming surface hydroxyls. Recombination of two surface hydroxyl groups V鈥揙H to form adsorbed H₂O, followed by water desorption, completes the catalytic dehydration cycle without participation of the formate species. Comparison of the reaction pathways demonstrates that both dehydrogenation and dehydration of formic acid may occur over VO_x/TiO₂ model catalysts with the preferable dehydration pathway.