Direct Evidence of Dynamic Metal Support Interactions in Co/TiO₂ Catalysts by Near-Ambient Pressure X-ray...

Area of Science:

• Heterogeneous catalysis
• Materials science
• Surface chemistry

Background:

• Metal-support interactions are critical for catalyst performance.
• Cobalt on titanium dioxide (Co/TiO2) is vital for Fischer-Tropsch synthesis.
• Understanding dynamic changes in Co/TiO2 under reaction conditions is essential.

Purpose of the Study:

• To investigate in situ the dynamic evolution of Co/TiO2 catalysts under various gas atmospheres.
• To elucidate the impact of gas phase environment on metal-support interactions.
• To explore the effect of NaBH4 modification on TiO2 support properties.

Main Methods:

• In situ soft and hard X-ray photoemission spectroscopy.
• Simultaneous probing of surface and subsurface chemical composition.
• Investigation of Co/TiO2 on pure and NaBH4-modified TiO2.

Main Results:

• Under H2, cobalt particles are encapsulated by a TiO2 layer.
• This encapsulation is maintained during CO2 hydrogenation (CO2:H2).
• Exposure to O2 rapidly alters the Co/TiO2 structure; NaBH4 pretreatment inhibits TiO2 spillover.

Conclusions:

• The gas atmosphere significantly influences the dynamic restructuring of Co/TiO2 catalysts.
• NaBH4 pretreatment enhances catalyst stability by preventing TiO2 encapsulation.
• In situ X-ray photoemission spectroscopy provides crucial insights into structure-performance relationships.