First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

SURFACE SCIENCE

卷:605

Article

Saadi, Souheil^1,2  Hinnemann, Berit¹  Appel, Charlotte C.¹  Helveg, Stig¹  Abild-Pedersen, Frank²  Norskov, Jens K.^2,3,4 

[1] Haldor Topsoe Res Labs, DK-2800 Lyngby, Denmark

[2] Tech Univ Denmark, Dept Phys, Ctr Atom Scale Mat Design, DK-2800 Lyngby, Denmark

[3] SLAC Natl Accelerator Lab, Ctr Interface Sci & Catalysis, Menlo Pk, CA 94025 USA

[4] Stanford Univ, Dept Chem Engn, Stanford, CA 94305 USA

关键词: Metal dusting;    Oxide scale;    Steam reforming;    Ni alloys;    Density functional theory;    Ni3Al;    NiAl;    Carbon;   

DOI  :  10.1016/j.susc.2010.12.023

来源: Elsevier

【 摘 要 】

We investigate the structure and surface composition of the gamma'-Ni3Al(111) and beta-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel-aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni3Al and NiAl surfaces, the conditions under which CO and OH adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases. (C) 2010 Elsevier B.V. All rights reserved.

【 授权许可】

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