Bridging the Pressure Gap in CO Oxidation

Area of Science:

• Catalysis
• Surface Science
• Materials Science

Background:

• Operando catalysis studies are crucial for industrial catalyst development.
• Previous operando X-ray photoelectron spectroscopy (XPS) experiments were limited to low pressures, questioning their industrial relevance.

Purpose of the Study:

• To perform fundamental operando catalysis studies under industrially relevant conditions.
• To investigate carbon monoxide oxidation on Pd(100) at 1 bar using XPS.
• To analyze the surface chemical composition and kinetics at the atomistic level.

Main Methods:

• Operando X-ray photoelectron spectroscopy (XPS) at 1 bar total pressure.
• Utilized hard X-rays and a grazing incident angle for high-pressure and surface sensitivity.
• In situ oxidation study at 70 mbar to confirm surface sensitivity and peak assignments.

Main Results:

• Successfully monitored CO oxidation on Pd(100) at 1 bar, observing gas-phase photoemission peaks for CO2, CO, and O2.
• Determined reaction kinetics and calculated activation energy during the light-off regime.
• Identified a metallic Pd phase in the highly active regime, with no oxygen-induced peaks observed during reaction.

Conclusions:

• Demonstrated the capability of operando XPS with hard X-rays for high-pressure catalysis studies.
• Achieved atomistic chemical information of catalysts under industrially relevant conditions.
• Opened new possibilities for understanding and optimizing industrial catalytic processes.