Journal
APPLIED SURFACE SCIENCE
Volume 453, Issue -, Pages 309-319Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apsusc.2018.05.047
Keywords
Cobalt; Fischer-Tropsch synthesis; Promoter; Deactivation; Density functional theory
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Funding
- National Natural Science Foundation of China [21476155, 21776193]
- Key Projects of National Natural Science Foundation of China [21736007]
- China Scholarship Council [201606935026]
- Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi
- Top Young Innovative Talents of Shanxi
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In order to probe into the roles of the promoters Pt, Ru and B in inhibiting the deactivation of Co catalysts in FTS reactions, the adsorption ability of neighboring surface C and subsurface C atom around the promoters (Pt, Ru and B), and the mechanisms of surface C diffusion, accumulation, hydrogenation and penetration are examined by density functional theory calculations over the promoters Pt, Ru and B-modified Co catalysts, as well as the pure Co catalysts. Our results clearly show that compared to Co catalysts, both PtCo and RuCo bimetallic catalysts promote surface C hydrogenation, and inhibit surface C diffusion, accumulation and penetration, and therefore the ability of resistance toward deactivation and the stability of Co-based catalysts are enhanced; the promoter B cannot effectively improve the ability of resistance toward deactivation. Thus, the sequence for resistance toward deactivation of Co-based catalyst is BCo < Co < PtCo < RuCo. Moreover, the activation free energy of surface C accumulation to C-2 species increases with the increasing of surface C adsorption free energy, namely, the adsorption characteristic of surface C species well represent the surface carbon deposition. Our results not only give an explanation for reported experiment that the Pt, Ru and B-modified Co catalysts exhibit ability of resistance toward deactivation in FTS at a molecular level, but also provide a clue for the design of efficient Co-based catalysts in FTS reactions. (C) 2018 Elsevier B.V. All rights reserved.
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