Deactivation of cobalt catalyst supported on carbon nanotubes (CNTs) in Fischer–Tropsch synthesis (FTS) was investigated by considering different deactivation mechanisms. The changes in the cobalt catalyst morphology during FTS reaction were studied using different techniques. The experimental results show that the sintering of cobalt particles is the dominant mechanism in deactivation of Co/CNTs catalyst, because of no interaction between support and active phase. Thus, the growth of cobalt particle size has been evaluated using a novel model in the catalyst deactivation. In this novel method, a new thermodynamically size dependent kinetic equation is used to investigate the crystal growth during the catalyst deactivation. The difference between experimental FTS results and calculated results using the new model is can be related to other deactivation mechanisms.

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