Influence of Pre-Carburization on Performance of Industrial Cobalt-Based Pelletized Fischer–Tropsch Catalyst

Abstract

The deposition of nanostructured carbon particles on the surface of a catalyst (carburization) is routinely considered an inalienable and undesirable secondary process in Fischer–Tropsch synthesis. However, very little is known about the actual role of the nanocarbon particles and how they influence catalysis. This paper reports research on the influence of carbon deposition on the performance of a cobalt-based Fischer–Tropsch-synthesized catalyst in an industrial-scale fixed-bed reactor (length—6000 mm, inner diameter—16.5 mm). The comparison of the structure and catalytic performance of a pelletized cobalt catalyst with the same catalyst, which was preliminary carburized, is presented. Pellet pore structure, catalyst surface, cobalt cluster morphology and the main catalytic properties (CO conversion, C5+ hydrocarbon productivity and selectivity to C5+ hydrocarbons and CH4 formation) were investigated. It is shown that the primary pre-carburization effect is a result of the physical blockage of the catalyst pore structure not followed by drastic changes in the cobalt cluster’s structure.