First-Principles Study of Low Miller Index Ni3S2 Surfaces in Hydrotreating Conditions

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• 作者：Yosslen Aray* ; David Vega ; Jesus Rodriguez ; Alba B. Vidal ; Maria Elena Grillo ; Santiago Coll
• 刊名：Journal of Physical Chemistry B
• 出版年：2009
• 出版时间：March 12, 2009
• 年：2009
• 卷：113
• 期：10
• 页码：3058-3070
• 全文大小：757K
• 年卷期：v.113,no.10(March 12, 2009)
• ISSN：1520-5207

文摘

Density functional theory (DFT) calculations combined with surface thermodynamic arguments and the Gibbs−Curie−Wulff equilibrium morphology formalism have been employed to explore the effect of the reaction conditions, temperature (T), and gas-phase partial pressures (p_H2 and p_H2S) on the stability of nickel sulfide (Ni₃S₂) surfaces. Furthermore, the strength and nature of chemical bonds for selected Ni₃S₂ surface cuts were investigated with the quantum theory of atoms in molecules methodology. A particular analysis of the electrostatic potential within this theoretical framework is performed to study the potential activity of nickel sulfide nanoparticles as hydrodesulfurization (HDS) catalysts. The calculated thermodynamic surface stabilities and the resulting equilibrium morphology model suggest that unsupported Ni₃S₂ nanoparticles mainly expose (111) and (11) type surface faces in HDS conditions. Analysis of the electrostatic potential mapped onto a selected electron density isocontour (0.001 au) on those expose surface reveals a poor potential reactivity toward electron-donating reagents (i.e., low Lewis acidity). Consequently, a very low attraction between coordinatively unsaturated active sites (Lewis sites) exposed at the catalytic particles and the S atoms coming from reagent polluting molecules does inactive these kinds of particles for HDS.