Model catalysts for studying hydrogen spillover effect on Fischer-Tropsch synthesis catalysts are described. Co and Ru nanoparticles were separated by encapsulating the Co nanoparticles inside a hollow carbon sphere (MHCS) support, while the Ru was exclusively loaded on the outer surface (i.e. Co@MHCS@Ru). Two other catalysts, unpromoted Co@MHCS and promoted CoRu@MHCS were also prepared. The syntheses were achieved by using polystyrene spheres (PSSs) as a template, covered by a resorcinol-formaldehyde carbon layer, and thermal removal of the PSSs. TEM analysis of the materials showed Co3O4 particles with an average size between 7.1-7.4 nm and Ru nanoparticle size of 2.6 nm with the MHCS defective carbon shell thickness between 20-30 nm. The catalysts were studied by classical techniques as well as STEM and HAADF. Pulse chemisorption experiments provided information on a primary hydrogen spillover effect that was used to explain the high Co dispersion for CoRu@MHCS in relation to the Co@MHCS@Ru and Co@MHCS dispersion after reduction at 350 . In situ PXRD studies revealed a secondary hydrogen spillover process over the porous carbon that can explain the complete reduction of the Co3O4 on Co@MHCS@Ru when compared to unpromoted Co@MHCS. Finally, a primary spillover effect was revealed to be more favourable than a secondary hydrogen spillover effect in the Co reduction process. Fischer-Tropsch tests of the catalysts showed that the Fischer-Tropsch activity was proportional to the degree of Co reduction which increased with the Co-Ru intimate contact. The Ru promoter also enhanced the production of paraffinic products and methane.

Fischer-Tropsch synthesis in a carbon nanoreactor: Spillover effects observed in Co@MHCS@Ru

2019 Fall National Meeting

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