Support effects on Ru-based catalysts for Fischer-Tropsch synthesis to olefins

The effects of supports (CeO₂, ZrO₂, MnO₂, SiO₂ and active carbon) on the structure and catalytic performance of Ru-based catalysts for Fischer-Tropsch synthesis to olefins (FTO) were investigated. It was found that the intrinsic characteristics of supports and the metal-support interaction (MSI) would greatly influence the catalytic performance. The catalytic activity followed the order: Ru/SiO₂ > Ru/ZrO₂ > Ru/MnO₂ > Ru/AC > Ru/CeO₂. As far as olefins selectivity was concerned, both Ru/SiO₂ and Ru/MnO₂ possessed high selectivity to olefins (>70%), while olefins selectivity for Ru/ZrO₂ was the lowest (29.9%). Ru/SiO₂ exhibited the appropriate Ru nanoparticles size ( ~ 5 nm) with highest activity due to the relatively low MSI between Ru and SiO₂. Both Ru/AC and Ru/MnO₂ presented low CO conversion with Ru nanoparticles size of 1−3 nm. Stronger olefins secondary hydrogenation capacity led to the significantly decreased olefins selectivity for Ru/AC and Ru/ZrO₂. In addition, partial Ru species might be encapsulated by reducible CeO₂ layer for Ru/CeO₂ due to strong MSI effects, leading to the lowest activity.