Factors Controlling the Energy of Nitrogen Monolayer Coverage on High Surface Area Catalyst Oxide Carriers

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• 作者：Francesco Arena ; Francesco Ferrante ; Lorenzo Spadaro ; Antonio Prestianni ; Antonino Raneri ; Dario Duca
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：December 22, 2011
• 年：2011
• 卷：115
• 期：50
• 页码：24728-24733
• 全文大小：925K
• 年卷期：v.115,no.50(December 22, 2011)
• ISSN：1932-7455

文摘

Factors affecting the strength of nitrogen physisorption at monolayer coverage on different catalytic oxide carriers (e.g., ZnO, MgO, Al₂O₃, ZrO₂, TiO₂, and SiO₂) have been addressed. Isotherm elaboration by the two-parameter BET equation provides C-constant values (80鈥?00) inversely related to the polarizing power (PP) of the oxide adsorbent irrespective of the surface area exposure. The energy of monolayer formation depends on the extent of charge-delocalization characterizing the surface cation-oxygen bond, which determines the acid鈥揵ase character of the oxide and strength of van der Waals interactions with adsorbate molecules. Density functional theory (DFT) calculations on MgO and TiO₂ systems support experimental BET findings, showing enhanced electron-density gradients and adsorption energy of the N₂ molecule on the former system owing to a stronger polarity of the Mg鈥揙 bond.