Bonding and thermal decomposition of propylene, propadiene, and methylacetylene on the Rh(111) single-crystal surface

Journal Article · Thu Mar 12 04:00:00 EST 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100290a042· OSTI ID:6868888

Bent, B E; Mate, C M; Crowell, J E; Koel, B E; Somorjai, G A

The reactions of propylene, propadiene, and methylacetylene with Rh(111) crystal faces in ultrahigh vacuum (UHV) from 80 to 800 K have been studied by low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy (HREELS), and thermal desorption spectroscopy (TDS). All three hydrocarbons adsorb intact at 80 K. At this temperature, methylacetylene forms a p(2 x 2) LEED pattern while propylene and propadiene adsorb as disordered monolayers. Above 200 K, propylene and propadiene also form p(2 x 2) LEED patterns which are stable up to 270 K. The propylene fragment in this temperature range is propylidyne (CCH/sub 2/CH/sub 3/). By room temperature all the C/sub 3/ hydrocarbons have decomposed to ethylidyne (CCH/sub 3/) and polymerized C/sub x/H fragments. Surface hydrogen is instrumental in the C-C bond breaking, and partial deuteriation studies were performed to determine which C-C bonds break first. The ethylidyne species are stable up to 400 K, above which they decompose to C/sub x/H fragments. The bonding and the thermal decomposition pathways for propylene on Rh(111) are compared to Pt(111) surface chemistry.

• Research Organization: Lawrence Berkeley Lab., CA
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6868888
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:6; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACETYLENE
ADSORPTION
ALKENES
ALKYNES
CHEMICAL BONDS
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTALS
DATA
DESORPTION
DIENES
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY-LOSS SPECTROSCOPY
EXPERIMENTAL DATA
HIGH TEMPERATURE
HYDROCARBONS
INFORMATION
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLATINUM METALS
POLYENES
PROPYLENE
RHODIUM
SCATTERING
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS
ULTRAHIGH VACUUM