High-resolution electron energy loss spectroscopy and thermal programmed desorption studies of the chemisorption and thermal decomposition of ethylene and acetylene on Ni(100) single-crystal surfaces

Journal Article · Thu Jul 30 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100300a023· OSTI ID:6137948

Zaera, F; Hall, R B

The chemisorption and thermal decomposition of acetylene and ethylene on Ni(100) surfaces were studied by using thermal programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Acetylene chemisorbs molecularly at 90 K forming a rehybridized (sp/sup 3/) acetylenic moiety on the surface. This fragment is stable up to 270 K, where dehydrogenation takes place to form CCH residues. Heating further, above 400 K, leaves only carbon on the nickel surface. Ethylene also adsorbs molecularly but with little rehybridization, H bonding to the metal. Stepwise dehydrogenation takes place as the crystal temperature is increased. Vinyl is formed as a product of a unimolecular reaction at 170 K for low coverages of ethylene (theta less than or equal to 0.4), but this process is inhibited at higher coverages and only takes place around 200 K. A strong isotope effect was also observed, and C/sub 2/D/sub 4/ decomposition only occurred at temperatures about 40 K higher. Vinyl decomposes further to form an acetylenic moiety at about 230 K. Further heating is followed by stepwise dehydrogenation similar to that observed when acetylene is adsorbed. No H-D scrambling is observed during the thermal treatment for partially or fully deuterated molecules.

• Research Organization: Univ. of California, Riverside
• OSTI ID: 6137948
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:16; ISSN JPCHA
• Country of Publication: United States
• Language: English

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ACETYLENE
ALKENES
ALKYNES
CHEMICAL REACTIONS
CHEMISORPTION
DATA
DECOMPOSITION
DESORPTION
DEUTERIUM COMPOUNDS
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY-LOSS SPECTROSCOPY
ETHYLENE
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALS
NICKEL
NUMERICAL DATA
ORGANIC COMPOUNDS
PYROLYSIS
RESOLUTION
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
SURFACES
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS