Density Functional Theory Study of Organosulfur Selective Adsorption on Ag鈥揟iO2 Adsorbents

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• 作者：A. H. M. Shahadat Hussain ; Michael L. McKee ; John M. Heinzel ; Xueni Sun ; Bruce J. Tatarchuk
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 10, 2014
• 年：2014
• 卷：118
• 期：27
• 页码：14938-14947
• 全文大小：471K
• ISSN：1932-7455

文摘

Ag鈥揟iO₂ adsorbents have pronounced capacity for selective removal of organosulfur compounds from complex fuel mixtures. Computational calculations were performed to investigate the nature of this pronounced selectivity as well as to study the adsorbent structure. A cluster model was developed for this study. Geometry optimization, frequency analysis, and single-point energy calculations were carried out using density functional theory (B3LYP/6-31G(d)(ECP=SDD(Ag,Ti))//B3LYP/LANL2DZ). The computed adsorption energies included dispersion terms (GD3) and were corrected for basis set superposition errors (BSSEs). Silver incorporated onto anatase鈥揟iO₂ clusters and with greater preference in the presence of 鈭扥H groups. Adsorption energies were calculated for sulfur-containing species (thiophene, benzothiophene, dibenzothiophene, 4,6-dimethyldibenzothiophene) and nonsulfur aromatics (quinoline, benzofuran, naphthalene, benzene) typically present in fuel mixtures. Calculated adsorption energies are consistent with the selective binding of organosulfur compounds through the Ag atom of the AgTi₆O₈(OH)₈ cluster rather than the 鈭扥H groups of the titania analogue. The adsorption orientation of organosulfur compounds was 蟺-preferred. Heterocycles with more aromatic rings were adsorbed more strongly. Organonitrogen compounds (i.e., quinoline) showed the strongest adsorption. Results from equilibrium saturation adsorption experiments were also compared with DFT calculations, and the trends and selective separation factors were shown to be in good agreement.