Co inside hollow carbon spheres as a Fischer-Tropsch catalyst: Spillover effects from Ru placed inside and outside the HCS

Hollow carbon spheres (HCSs) containing Co nanoparticles placed inside the HCS were synthesized for the first time using polystyrene spheres as a template. The encapsulated Co nanoparticles, after reduction, showed Fischer-Tropsch (FT) activity indicating syngas accessibility through the HCS porous shell. Two Co catalysts promoted by Ru, placed either inside or outside the HCS (CoRu@HCS and Co@HCS@Ru), were also synthesized and characterized. The location of the Co and Ru was confirmed by SEM and TEM analyses. In-situ XRD studies indicated enhanced H-2 reduction of the Co oxide to Co, inside the HCS, in the order CoRu@HCS > Co@HCS@ Ru > Co@HCS. The CoRu@HCS catalyst had the highest FT activity, and this was ascribed to a primary spillover effect associated with the direct contact of the Co and Ru inside the HCS. A small secondary spillover effect was also noted for Co@HCS@Ru.