Fischer–Tropsch synthesis over cobalt catalyst supported on carbon nanotubes in a slurry reactor

Abstract

Abstract The potential of carbon nanotubes (CNTs) supported cobalt catalysts for Fischer–Tropsch (FT) reaction is discussed in this paper. Cobalt on carbon nanotube catalysts were prepared using the wet impregnation method with cobalt loading varying from 15 to 40 wt.%. The catalysts were characterized by BET, X-ray diffraction (XRD), H2 chemisorption, TPR, and transmission electron microscopy (TEM). The activity and selectivity of the catalysts were assessed using a continuous stirred tank reactor (CSTR). Most of the cobalt particles were homogeneously distributed inside the tubes and the rest on the outer of the CNTs. Carbon nanotubes as cobalt catalyst support was found to shift the reduction temperature of cobalt oxide species to lower temperatures. The strong metal–support interactions are reduced to a large extent and the reducibility of the catalysts improved significantly. CNT aided in well dispersion of metal clusters and average cobalt clusters size decreased. The hydrocarbon yield in the FT process obtained by CNT-supported cobalt catalyst is about 75% more than that obtained using cobalt on alumina supports. The maximum concentration of active surface Co° sites and FTS activity for CNT-supported catalysts are achieved at 40 wt.% cobalt loading. CNT caused a slight decrease in FTS product distribution to lower molecular weight hydrocarbons.