Preparation of a Novel Super Active Fischer-Tropsch Cobalt Catalyst Supported on Carbon Nanotubes

The potential of carbon nanotubes (CNT) supported cobalt catalysts for Fischer-Tropsch (FT) reaction is shown. Using the wet impregnation method cobalt on carbon nanotubes catalysts were prepared with cobalt loading varying from ۱۵ to ۴۵ wt. %. The catalysts are characterized by different methods including: BET physisorption, X-ray diffraction, hydrogen chemisorption, and temperature-programmed reduction. The activity and product selectivity of the catalysts were assessed and compared with alumina supported cobalt catalysts using a continuous-stirred tank reactor (CSTR). Using carbon nanotubes as cobalt catalyst support was found to decrease the reduction temperature of Co۳O۴ to CoO from ۴۴۰ to ۳۴۷ oC and that of CoO to Coo from ۶۴۰ to ۵۷۴ oC. The strong metal-support interactions are reduced to a large extent and the reducibility of the catalysts improved by ۶۷.۷ %. CNT aided in well dispersion of metal clusters and average cobalt clusters size of the reduced cobalts is decreased from ۵.۳ to ۴.۹ nm. Results are presented showing that the hydrocarbon yield obtained by CNT supported cobalt catalyst is ۷۴.۶ % more than that obtained from cobalt on alumina supports. The maximum concentration of active surface Coo sites and FTS activity for CNT supported catalysts are achieved ۴۰ wt. % cobalt loading. CNT caused a slight decrease in the FTS product distribution to lower molecular weight hydrocarbons.

کلیدواژه ها:

Fischer-Tropsch synthesis ، Cobalt ، Carbon Nanotube ، Reducibility ، reaction rate