Hydrogen Spillover in the Fischer-Tropsch Synthesis on Carbon-supported Cobalt Catalysts

The Fischer-Tropsch reaction transforms syngas into high added value products, among which liquid fuels. Numerous parameters determine catalytic activity and selectivity towards the most desired hydrocarbons. The performances of cobalt-based catalysts used in the reaction are known to depend critically on Co particle size and crystallographic phase. Here, we present a comparative study of Co-based catalysts supported on three carbon supports: multi-wall carbon nanotubes, carbon nanofibers and a fibrous material. Our results show that, while the selectivity towards C5+ follows the expected tendency with respect to Co particle size, this is not the case for the TOF. These results can be rationalized considering that the amount of H-2 uptake on each catalyst increases with oxygen and defect concentration on the support. The catalyst on the support presenting many edges and oxygen surface groups, necessary for H-2 spillover, presents the highest activity. Furthermore, the hydrogen spillover contributes to the enhancement of olefin hydrogenation and methane production.