Hydrogenation of CO and CO/sub 2/ on clean rhodium and iron foils. Correlations of reactivities and surface compositions

Conference · Fri Dec 16 00:00:00 EST 1977

OSTI ID:5178615

Dwyer, D; Yoshida, K; Somorjai, G A

An experimental arrangement consisting of an ultrahigh vacuum bell jar equipped with an internal sample isolation cell was used to investigate the hydrogenation of CO over Fe and Rh surfaces. This apparatus permitted both UHV surface characterization (Auger electron spectroscopy, low-energy electron diffraction) and high pressure (1-20 atm) catalytic reactions to be carried out. Small surface area (approximately 1 cm/sup 2/) metal samples, both single crystals and polycrystalline foils, were used to catalyze the H/sub 2//CO reaction at high pressures (1-6 atm). Reaction products were monitored with a gas chromatograph equipped with a flame ionization detector. The surface compositions of the metal samples were determined before and after the reaction and the results correlated with the observed product distributions and reaction rates. In addition, the influence of various surface additives (carbon, oxygen, potassium) was also investigated. Iron was the more reactive of the two metals studied and was found to produce C/sub 1/-C/sub 5/ straight chain hydrocarbons but it poisoned rapidly. The catalytically active surface of both metals was covered with a carbonaceous monolayer. The carbonaceous monolayer was stable on the rhodium surface and produced C/sub 1/-C/sub 4/ hydrocarbons at a steady rate even after several hours of reaction. The absolute rates on rhodium samples were, however, substantially lower than those observed for the catalytically active iron samples. Differences in the poisoning characteristics and product distributions of the initially clean metal surfaces and the promoted rhodium and iron catalysts indicate the importance of additives and the formation of surface compounds in controlling the activity and selectivity.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5178615
• Report Number(s): LBL-6989; CONF-780305-12
• Resource Relation: Conference: Division of fuel chemistry meeting, Anaheim, CA, USA, 12 Mar 1978
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
CARBON DIOXIDE
METHANATION
CARBON MONOXIDE
IRON
CATALYTIC EFFECTS
RHODIUM
CATALYSIS
CHEMICAL REACTION KINETICS
MEDIUM PRESSURE
MONOCRYSTALS
POLYCRYSTALS
PROMOTERS
SURFACE PROPERTIES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTALS
ELEMENTS
KINETICS
METALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
REFRACTORY METALS
TRANSITION ELEMENTS
090121* - Hydrocarbon Fuels- Chemical Synthesis- (1976-1989)