Catalytic reactions of n-alkanes on. beta. -W sub 2 C and WC: The effect of surface oxygen on reaction pathways

Journal Article · Thu Aug 01 04:00:00 EDT 1991 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(91)90131-M· OSTI ID:5794729

Ribeiro, F H; Boudart, M; Dalla Betta, R A ^[1]; Iglesia, E ^[2]

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1. Stanford Univ., CA (United States)
2. Exxon Research and Engineering Co., Annandale, NJ (United States)

Tungsten carbide powders with WC and {beta}-W{sub 2}C structures catalyze alkane hydrogenolysis reactions. Alkanes adsorb on fresh carbide surfaces strongly leading to rapid deactivation by carbon fragments and to high selectivity to hydrogenolysis products. n-Hexane isomerization or dehydrocyclization products were not observed on fresh carbides. Chemisorbed oxygen lowers the binding energy of adsorbed intermediates and decreases both hydrogenolysis and deactivation rates. Oxygen-exposed carbides catalyze n-hexane and n-heptane isomerization with high selectivity (74-99%). Isomerization involves methyl-shift pathways that require alkene intermediates. These results and the well-known acid properties of WO{sub x} surface species suggest that oxygen-exposed tungsten carbides catalyze bifunctional (dehydrogenation/carbenium-ion) alkane isomerization pathways.

• DOE Contract Number: FG03-87ER13762
• OSTI ID: 5794729
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 130:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ADSORPTION
ALKANES
ALKENES
CARBIDES
CARBON COMPOUNDS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
CONTROL
DEACTIVATION
DEHYDROCYCLIZATION
DEHYDROGENATION
ELEMENTS
HEPTANE
HEXANE
HYDROCARBONS
ISOMERIZATION
KINETICS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN
REACTION KINETICS
REDUCTION
REFRACTORY METAL COMPOUNDS
SEPARATION PROCESSES
SORPTION
SURFACE PROPERTIES
SYNTHESIS
TEMPERATURE CONTROL
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN CARBIDES
TUNGSTEN COMPOUNDS