Chemisorption and diffusion of atomic hydrogen in and on cluster models of Pd, Rh, and bimetallic PdSn, RhSn, and RhZn catalysts

Journal Article · Wed Nov 07 00:00:00 EST 1990 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00179a003· OSTI ID:5757660

Rochefort, A; Andzelm, J; Salahub, D R ^[1]; Russo, N ^[2]

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1. Univ. de Montreal, Quebec (Canada)
2. Univ. della Calabria, Cosenza (Italy)

Results of LCGTO-MCP-LSD (Linear Combination of Gaussian Type Orbitals-Model Core Potential-Local Spin Density) calculations are reported for chemisorption and for bulk and surface diffusion of atomic hydrogen on clusters simulating the (111) and (100) surfaces of pure transition metals (Pd and Rh) and bimetallic catalysts (PdSn, RhSn, and RhZn). The replacement of a Pd or Rh atom near the hydrogen atom by Sn decreases the binding energy for hydrogen adsorption. In particular, the decrease is most pronounced when the non-transition metal lies in the first surface layer (e.g. 3.8 eV (2.4 eV) for Pd (PdSn) and 4.1 eV (2.8 eV) for Rh (RhSn)) but is also significant when the non-transition metal is placed as a second neighbor (e.g. 3.8 eV (3.1 eV) for Pd(PdSn) and 4.1 eV (2.9 eV) for Rh(RhSn)). For Zn substitution the behavior is less regular, one case of an increase in binding energy has been found. The presence of Sn or Zn on the surface significantly increases the equilibrium bond distances (e.g. 1.76 {angstrom} for Pd{sub 3}Pd vs 1.93 {angstrom} for Pd{sub 2}SnPd) and decreases the hydrogen perpendicular vibrational frequencies (e.g. 1166 cm{sup {minus}1} for Pd{sub 3}Pd vs 988 cm{sup {minus}1} for Pd{sub 2}SnPd).

• OSTI ID: 5757660
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 112:23; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALLOYS
PERMEABILITY
HYDROGEN
CHEMISORPTION
DIFFUSION
PALLADIUM
RHODIUM
BINDING ENERGY
CATALYSTS
ENERGY LEVELS
MATHEMATICAL MODELS
MILLER INDICES
SOLID CLUSTERS
TIN ALLOYS
WAVE FUNCTIONS
CHEMICAL REACTIONS
ELEMENTS
ENERGY
FUNCTIONS
METALS
NONMETALS
PLATINUM METALS
SEPARATION PROCESSES
SORPTION
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties