Enhancement of CNTs Supported Cobalt Nanocatalyst Activity, Selectivity and Stability in Fischer-Tropsch Synthesis by Functionalization of Support with Ozone and Hydrogen Peroxide

Functionalization of carbon nanotubes (CNTs) was applied, during preparation of Fischer–Tropsch synthesis (FTS) cobalt nanocatalysts, to modify the surface properties of CNTs supports. Carbon nanotubes functionalization effects on the particle size, dispersion, activity and selectivity of Co/CNTs nanocatalyst in FTS werw investigated. CNTs were functionalized with ozone and hydrogen peroxide. 15 wt.% Cobalt was impregnated on the functionalized and un-functionalized supports. Catalyst samples were characterized by different methods and assessed in a fixed bed micro reactor. Optimal catalyst activity is usually dependent on the size of the active metal phase, so the catalyst metal particles on the support with finer particles showed higher activity due to higher distribution, than the catalyst with larger size and poor dispersion. This phenomenon is the consequence of the existence of more metal particles which are more accessible to the reactants. In this work, the presence of functional groups decreased the active metal particle size to 8.8 nm. Furthermore, functionalization increased the percentage conversion of carbon monoxide by a factor of 1.16%. In addition, rate of catalyst deactivation decreased by 46% during 20 days continues synthesis. Finally, synthesis products showed a slight shift to lighter hydrocarbons.