Improvement the promotional efficiency of Ru by controlling the position and distribution of RuO2 precursors on CoRu/SiO2 catalyst

The presence of polyethylene glycol (PEG) in a co-impregnation process reduced the crystallite size of Co3O4 and formed a close contact between the uniformly distributed RuO2 and Co3O4 particles on CoRuOx/SiO2 sample after calcination. This structure facilitated the reduction of small Co3O4 particles. The resultant small Co0 particles and Co-Ru synergistic effect enhanced the Co-time yield and turnover frequency (TOF) in Fischer–Tropsch synthesis. Comparatively, the PEG-free process led to the inhomogeneous distribution and segregation of RuO2 particles. These separated RuO2 precursors could improve the reduction of Co3O4, but had less impact on TOF in contrast to Ru-free Co/SiO2 catalyst.

► Promotional efficiency of Ru depends on the position and distribution of RuO2 precursors. ► Separated RuO2 precursors promote the reduction of Co3O4 but have less impact on TOF. ► Uniformly distributed RuO2 that contact with Co3O4 promote the reduction and TOF. ► Using PEG forms required structure due to the cation–oligomer interaction in liquid.