Kees-Jan Weststrate has recently presented his work on the crucial function of CO as intermediate in Fischer-Tropsch Synthesis at the European Conference on Surface Science in Aarhus, and in an international meeting in Taiyuan, China. His work will also appear in ACS Catalysis in the course of this Fall.
Adsorbed carbon monoxide is of course an essential ingredient in the conversion of syngas (CO+H2) to hydrocarbons, but the CO molecule fulfills another essential role which has until now hardly been appreciated: it enables the growth of hydrocarbon chains on the surface. Without CO, hydrocarbon fragments tend to loose their hydrogen atoms and degenerate to inactive coke, but CO in its immediate surroundings prevents this, and promotes the hydrocarbon species into alkylidynes, which can couple to larger hydrocarbons. The evidence comes from surface science experiments, with thermal desorption and infrared spectroscopy in the lead.
The ECOSS presentation is available for download here.
Without CO, hydrocarbons form ‘flat-lying’ species which tend to loose their hydrogen atoms and form inactive coke species, but with CO in their immediate vicinity hydrocarbon fragments reside in reactive states, which eventually form the hydrocarbon fuels.