Passivation of Co/Al2O3 Catalyst by Atomic Layer Deposition to Reduce Deactivation in the Fischer-Tropsch Synthesis

Abstract

The present work explores the technical feasibility of passivating a Co/γ-Al2O3catalyst byatomic layer deposition (ALD) to reduce deactivation rate during Fischer-Tropsch synthesis (FTS).Three samples of the reference catalyst were passivated using different numbers of ALD cycles (3, 6and 10). Characterization results revealed that a shell of the passivating agent (Al2O3) grew aroundcatalyst particles. This shell did not affect the properties of passivated samples below 10 cycles, inwhich catalyst reduction was hindered. Catalytic tests at 50% CO conversion evidenced that 3 and6 ALD cycles increased catalyst stability without significantly affecting the catalytic performance,whereas 10 cycles caused blockage of the active phase that led to a strong decrease of catalytic activity.Catalyst deactivation modelling and tests at 60% CO conversion served to conclude that 3 to 6 ALDcycles reduced Co/γ-Al2O3deactivation, so that the technical feasibility of this technique was provenin FTS.