Structural evolution, stability, deactivation and regeneration of Fischer-Tropsch cobalt-based catalysts supported on carbon nanotubes

Though carbon nanotubes (CNTs) are widely applied in industry, their large-scale use in catalysis is still limited. This work studies cobalt-based CNT-supported catalysts with 20 and 30 % metal loadings in Fischer-Tropsch synthesis at relevant conditions. The evolution of catalyst and support structures was analyzed by a combination of physicochemical methods at different stages of catalysts preparation, long-term tests, regeneration, and retest. Wax accumulation was suggested to be the main reason for catalyst deactivation, while sintering and carbidization did not strongly affected the catalyst performance. Moreover, sintering played a positive role by increasing conversion and C5+ selectivity because of the consolidation of low active small particles. The reductive regeneration of the used catalysts restored their maximum activities. The mild and optimally chosen conditions of the catalyst preparation, activation and regeneration preserved the support structure improving the overall stability of the Co/CNT catalysts that is necessary for large-scale catalytic applications.