Fischer–Tropsch synthesis over Pt/Co/Al2O3 catalyst: Improvement in catalyst stability by activation with diluted CO

Abstract

Fischer–Tropsch cobalt-based catalyst deactivation is one of the major challenges facing gas-to-liquids processes. Changes in catalyst formulation and pre-treatment methods are among the promising routes to address this challenge. In this study, diluted CO was used to pre-treat a 0.5%Pt/25%Co/Al2O3 catalyst, in comparison to H2, and the resulting effects on catalyst stability, activity and product selectivity were evaluated. The investigation was performed using BET, TEM, TPR, XPS and XRD techniques, combined with catalyst evaluation in a 1 L continuously stirred tank reactor. The results reveal that microporous carbon shells encapsulate Co particles during activation by CO at higher temperatures, resulting in lower activity and higher methane selectivity compared to the H2-reduced catalyst, at early reaction times. However, the CO-activated catalyst displayed superior stability, resulting in better performance at extended time-on-stream compared to a deactivating H2-activated catalyst, which showed an increase in CH4 selectivity and a decline in C5+ hydrocarbon formation rate.