Chemisorption and surface reactions of D/sub 2/ and hydrocarbons on the Re(0001) single-crystal surface clean and in the presence of coadsorbed sulfur or carbon
The chemisorption and surface reactions of thiophene, D/sub 2/, and the hydrodesulfurization products (1,3-butadiene and butenes) have been studied on Re(0001) at low ambient pressure (10/sup -9/ Torr) by using thermal desorption spectroscopy (TDS), low energy electron diffraction (LEED), and Auger electron spectroscopy (AES). D/sub 2/ adsorption was found to be blocked by sulfur or carbon overlayers. Sulfur preadsorption induced small changes in the D/sub 2/ desorption energy, and adsorption was completely blocked above 0.4 monolayer of sulfur (theta/sub s/ = 0.4). Carbon preadsorption lowered the temperature of the desorption maxima (380 to 290 K), and blocked D/sub 2/ adsorption nonlinearly. Sequential dehydrogenation of the adsorbed unsaturated hydrocarbons leading to complete decomposition at high temperatures (> 700 K) was observed on the clean Re(0001) surface. Addition of sulfur or carbon blocked dehydrogenation. No changes in the dehydrogenation (yielding H/sub 2/) TDS peak temperatures were observed for either sulfur or carbon preadsorption. However, selective blocking of dehydrogenation states was observed for both sulfur and carbon preadsorption. In addition, carbon adsorption did allow hydrogenation of butadiene to occur. It is concluded that for all systems preadsorbed sulfur acts as a site blocker for adsorption and dissociation with only small effects on bonding of adsorbed molecules on Re(0001). Although this also seems to be true for preadsorbed carbon as well, other subtle effects are observed that can change the surface chemistry of adsorbed molecules, as exemplified by the hydrogenation of butadiene.
- Research Organization:
- Lawrence Berkeley Lab., CA
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5572108
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BUTADIENE
CHEMISORPTION
DISSOCIATION
BUTENES
DEUTERIUM COMPOUNDS
POLYCYCLIC SULFUR HETEROCYCLES
RHENIUM
MONOCRYSTALS
AUGER ELECTRON SPECTROSCOPY
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
ELECTRON DIFFRACTION
EXPERIMENTAL DATA
HIGH TEMPERATURE
MILLER INDICES
ALKENES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTALS
DATA
DIENES
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
POLYENES
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties