Adsorption and catalysis on silicon-modified W(110) surfaces

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(90)90046-M· OSTI ID:5629306

Sault, A G; Goodman, D W ^[1]

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1. Sandia National Labs., Albuquerque, NM (USA) Texas A and M Univ., College Station, TX (USA)

The adsorption of CO, hydrogen, and benzene was studied at 120 K on silicon-covered W(110) surfaces using temperature-programmed desorption. The saturation coverage of virgin CO is reduced from 0.80 monolayer (ML) on the clean W(110) surface to 0.l40 ML in the presence of 0.30 ML of silicon and to 0.21 ML in the presence of 0.56 ML of silicon. No CO adsorption occurs on W(110) covered by a monolayer of silicon. Dissociation of hydrogen, CO, and benzene is strongly inhibited by silicon. This inhibition of CO and hydrogen adsorption by silicon is discussed in terms of the proposed overlayer structures for silicon on W(110). Upon annealing silicon overlayers to 1050 K, silicon diffuses into the bulk to form tungsten silicide, and the resulting increase in the concentration of tungsten atoms at the surface increases the ability of the surface to adsorb CO. Results are compared to those from adsorption studies on silicon-covered polycrystalline tungsten and on a nickel disilicide surface. The dehydrogenation and hydrogenolysis of cyclohexane were used to test the catalytic properties of the silicon-modified surfaces. Tungsten silicide appears to be a highly selective catalyst for the dehydrogenation of cyclohexane. Comparison with a study of cyclohexane reactions over silane-treated nickel catalysts indicates that high selectivity for dehydrogenation may be a general attribute of silicon-modified metal catalysts. The activity of tungsten silicide for cyclohexane dehydrogenation to benzene is at least as great as that of the Ru(0001) surface.

• OSTI ID: 5629306
• Journal Information: Journal of Catalysis; (USA), Vol. 126:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
BENZENE
ADSORPTION
CARBON MONOXIDE
CYCLOHEXANE
DEHYDROGENATION
HYDROGEN
TUNGSTEN
CATALYTIC EFFECTS
SORPTIVE PROPERTIES
TUNGSTEN SILICIDES
ANNEALING
COMPARATIVE EVALUATIONS
DESORPTION
DISSOCIATION
INHIBITION
LAYERS
NICKEL SILICIDES
RUTHENIUM
SILICON
SYNTHESIS
TEMPERATURE CONTROL
ALKANES
AROMATICS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CONTROL
CYCLOALKANES
ELEMENTS
HEAT TREATMENTS
HYDROCARBONS
METALS
NICKEL COMPOUNDS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REFRACTORY METAL COMPOUNDS
SEMIMETALS
SILICIDES
SILICON COMPOUNDS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN COMPOUNDS
020400* - Petroleum- Processing