Intrinsic Kinetics of Fischer–Tropsch Synthesis over Co/CNTs Catalysts: Effects of Support Interaction

Abstract

The activities of cobalt catalysts prepared by the microemulsion impregnation method on carbon nanotubes (CNTs) and functionalised carbon nanotubes (FCNTs) supports were evaluated in the Fischer–Tropsch synthesis (FTS). The catalysts were characterised by transmission electron microscopy, X-ray diffraction and Brunauer–Emmett–Teller surface area methods. The results show that the cobalt particles in the FCNTs support are mostly located inside the tubes of the CNTs and show a narrower particle size distribution. The experimental results show that the cobalt catalyst supported on FCNTs leads to a higher CO conversion and FTS activity compared to that supported on normal CNTs. Calculated kinetic results show that the activation energies fall within the narrow range of 101.1–107.1 kJ mol−1 and the heat of hydrogen adsorption was calculated to be −40.2 and −26.2 kJ mol−1 for Co/CNTs and Co/FCNTs catalysts respectively. FCNTs, as a catalyst support of Co nanoparticles, maintain high dispersion which can be attributed to a hydrogen spillover effect of functional groups on the CNT surface.