Study into optimizing the temperature regime for the reduction of Fischer–Tropsch synthesis catalysts

Objectives. The work set out to investigate the potential for developing an efficient cobalt catalyst for Fischer–Tropsch synthesis through low-temperature activation by reduction in hydrogen directly in the synthesis reactor. Such an approach could be used to enhance the overall economic viability of the process.

Methods. The reduction of a zeolite-containing catalyst with a heat-conducting system based on thermally expanded graphite in an aluminum oxide binder carrier was investigated within the temperature range of 300–400°C. The degree of reduction of the powdered catalyst (to remove diffusion restrictions) was determined by conducting temperature-programmed reduction subsequent to the reduction at the studied temperature. Autosorb-1C and STA 449 F1 (Netzsch, Germany) devices were used in this work. The identified activation mode was evaluated at a Fischer–Tropsch synthesis pilot plant at INFRA (Moscow, Russia).

Results. Activity and selectivity values of the catalyst reduced at 325°C are determined from chromatographic analysis of the products. Low-temperature (325°C) reduction is shown to provide better catalytic parameters due to the implementation of a larger number of highly dispersed cobalt-oxide structures fixed on the hydrated surface of the support, resulting in the appearance of Co^δ+ centers with increased activity and selectivity for the formation of C₅₊ hydrocarbons.

Conclusions. The described catalytic system demonstrates the potential advantages in carrying out reductive activation in hydrogen at 325°C as opposed to the conventional 400°C. This approach markedly enhances the economic viability of the entire process, particularly for small-scale installations, due to the reduced thermal stability of the steel material reactor.

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