Actions for First-principles studies of H2S adsorption and dissociation on metal surfaces [electronic resource].

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First-principles studies of H2S adsorption and dissociation on metal surfaces [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 2008.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
2,758-2,768 : digital, PDF file
Additional Creators
National Energy Technology Laboratory (U.S.), United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Exposure of Pd-based hydrogen purification membranes to H,S. a common contaminant in coal gasification streams, can cause membrane performance to deteriorate, either by deactivating surface sites required for dissociative H, adsorption or by forming a low-permeability sulfide scale. In this work. the composition, structure, and catalytic activity of Pd4S, a surface scale commonly observed in Pd-membrane separation of hydrogen from sulfur-containing gas streams, were examined using a combination of experimental characterization and density functional theory (DFT) calculations. A Pd,S sample was prepared by exposing a 100 f1m Pd foil to H2S at 908 K. Both X-ray photoemission depth profiling and low energy ion scattering spectroscopic (LEISS) analysis reveal slight sulfur-enrichment of the top surface of the sample. This view is consistent with the predictions of DFT atomistic thermodynamic calculations. which identified S-terminated Pd,S surfaces as energetically favored over corresponding Pd-terminated surfaces. Activation barriers for H2 dissociation on the Pd,S surfaces were calculated. Although barriers are higher than on Pd(lll). transition state theory analysis identified reaction pathways on the S-terminated surfaces for which hydrogen dissociation rates are high enough to sustain the separation process at conditions relevant to gasification applications
Report Numbers
E 1.99:netl-tpr3492
netl-tpr3492
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Note
Published through SciTech Connect.
01/01/2008.
"netl-tpr3492"
Surface Science 602 16 ISSN 0039-6028 FT
Alfonso, D.R.
View MARC record | catkey: 14447931