Article révisé par les pairs
Résumé : We have studied the CO hydrogenation over a Co/SiOl catalyst under mild reaction conditions (up to 4,4 bar total pressure, H2/CO = 2. T = 483 K) and performed a post-reaction analysis of the chemical surface composition by means of secondary ion mass spectrometry (SIMS) and temperature-programmed reaction (TPR) in hydrogen gas. A hydrocarbon chain growth probability alpha = 0.78 was found in the catalytic studies. The SIMS analysis revealed the existence of individually adsorbed C" Hv species up to CgH", in accordance with end-on bonding to the catalyst surface. These species were removed from the catalyst surface in the subsequent H2 TPR experiment. Significant methane desorption occurred at temperatures (>500 K) well above those of the longer-chain hydrocarbons indicating either an increasing hydrogenolysis activity of Co metal during H2-TPR or the presence of a more tightly bound "carbidic" adsorbate under FT conditions