Tuning the Size of TiO₂-Supported Co Nanoparticle Fischer-Tropsch Catalysts Using Mn Additions

Area of Science:

• Heterogeneous catalysis
• Materials science
• Surface chemistry

Background:

• Cobalt/titanium dioxide (Co/TiO2) catalysts are traditional for Fischer-Tropsch (FT) synthesis.
• Promoter addition is key to tuning catalyst selectivity and performance.

Purpose of the Study:

• To investigate the role of manganese (Mn) promoters in Co/TiO2 catalysts.
• To understand the evolution of elemental dispersion and chemical structure during H2 activation.
• To elucidate the mechanism behind Mn's influence on cobalt nanoparticle size and stability.

Main Methods:

• In situ gas cell scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) elemental mapping.
• Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS).
• Density functional theory (DFT) calculations.

Main Results:

• Mn addition reduces cobalt (Co) particle size and narrows the size distribution.
• Mn remains dispersed on the titania support after activation.
• DFT calculations suggest Mn has lower surface mobility and favorable interactions with Co, reducing Co sintering.

Conclusions:

• Mn promoters enhance the dispersion and stability of Co nanoparticles on TiO2.
• Understanding Mn's effect on Co particle size provides insights for designing advanced FT catalysts.
• These findings are applicable to other supported nanoparticle catalyst systems.