Density-functional theory (DFT) study of arsenic poisoning of NiMoS

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• 作者：Shaofeng Yang ; John Adjaye ; William C. McCaffrey ; Alan E. Nelson
• 关键词：Density-functional theory ; Nickel-promoted molybdenum sulfide ; Hydrotreating ; Organoarsenic ; Deactivation
• 刊名：Journal of Molecular Catalysis A: Chemical
• 出版年：2010
• 出版时间：14 April 2010
• 年：2010
• 卷：321
• 期：1-2
• 页码：83-91
• 全文大小：1253 K

文摘

Arsenic poisoning of NiMoS hydrotreating catalysts was studied using density-functional theory (DFT) calculations. The incorporation of arsenic into NiMoS by chemical adsorption and dissociation of organoarsenic molecules (AsH₃, (CH₃)₃As, (C₂H₅)₃As, and (C₆H₅)₃As) and the substitution of Ni and S atoms by arsenic on both fully promoted Ni(1 0 0)Mo- and Ni(1 0 0)S-edge surfaces were investigated. DFT calculation results show that the adsorption of organoarsenic compounds is energetically favored on both surfaces and there is a correlation between the adsorptivity of the arsenic compounds and their electronic structure. After the organoarsenic molecules have adsorbed on the edge surfaces, dissociation on a Ni(1 0 0)S-edge surface is energetically favored. Arsenic may substitute Ni atoms on both Ni(1 0 0)Mo-edge and Ni(1 0 0)S-edge surfaces. However, the substitution of S atoms by arsenic may only occur on the Ni(1 0 0)S-edge surface. The DFT results are compared with previously reported EXAFS studies on arsenic deposited NiMoP/Al₂O₃ hydrotreating catalysts.