Hydrogen chemisorption and oxidation of transition metal carbides

Technical Report · Mon Jan 01 00:00:00 EST 1979

DOI:https://doi.org/10.2172/5795618· OSTI ID:5795618

Bethin, J. R.

A study was made of the catalytic activity of WC, focusing on the possible influence of point defects. The chemisorption of H on WC and titanium oxycarbides was studied with differential scanning calorimetry. The catalytic activity of these materials for oxidation of H was determined by potentiostatic steady-state and potentiodynamic measurements in acid electrolyte. Compositions of WC surfaces were determined by x-ray photoemission and related to the catalytic behavior. Titanium oxycarbide surfaces were analyzed by Auger electron spectroscopy. Of the carbides tested only one WC preparation was able to chemisorb H. Both WC powders investigated catalyzed H oxidation with similar specific activities. Spectroscopic studies showed that the active surface of WC was a mixture of WO/sub 3/ and a carbon-deficient WC phase. This result indicates that carbon vacancies are the active sites in tungsten carbide. Theoretical models of a carbon vacancy surrounded by metal atoms suggested by calculations by other workers support this assignment and identify the important role of the W6s level. The measured value of the heat of chemisorption is consistent with the proposed model.

• Research Organization: Illinois Univ., Urbana (USA). Dept. of Ceramic Engineering
• DOE Contract Number: EY-76-C-02-1198
• OSTI ID: 5795618
• Report Number(s): COO-1198-1277; TRN: 79-021489
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
HYDROGEN
CHEMISORPTION
OXIDATION
TITANIUM CARBIDES
SORPTIVE PROPERTIES
TUNGSTEN CARBIDES
CATALYTIC EFFECTS
POINT DEFECTS
SURFACES
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CRYOGENIC FLUIDS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
FLUIDS
NONMETALS
SEPARATION PROCESSES
SORPTION
SURFACE PROPERTIES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties