CO as a Promoting Spectator Species of CxHy Conversions Relevant for Fischer-Tropsch Chain Growth on Cobalt: Evidence from Temperature Programmed Reaction and Reflection Absorption Infrared Spectroscopy

Cobalt-catalyzed low temperature Fischer–Tropsch synthesis is a prime example of an industrially relevant reaction in which CxHy intermediates involved in chain growth react in the presence of a large quantity of COad. In this study, we use a Co(0001) single-crystal model catalyst to investigate how CO, adsorbed alongside CxHy adsorbates affects their reactivity. Temperature-programmed reaction spectroscopy was used to determine the hydrogen content of the CxHy intermediates formed at different temperatures, and infrared absorption spectroscopy was used to obtain more specific information on the chemical identity of the various reaction intermediates formed. Ethene, propene, and but-1-ene precursors decompose below 200 K. The 1-alkyne adsorbate is identified as a major product, and some alkylidyne species form as well when the initial alkene coverage is high. The surface hydrogen atoms produced in the low temperature decomposition step start leaving the surface >300 K. When an alkyne/Had-covered surface i...