CO₂ coverage on Pd catalysts accelerates oxygen removal in oxy-combustion systems

Area of Science:

• Chemical Engineering
• Catalysis
• Combustion Science

Background:

• Oxy-combustion generates exhaust gases rich in carbon dioxide (CO2).
• Residual oxygen (O2) in CO2 streams limits their direct utilization.
• Methane (CH4) oxidation over palladium (Pd) catalysts shows promise for O2 removal.

Purpose of the Study:

• To investigate the impact of elevated CO2 concentrations on O2 removal efficiency via CH4 oxidation.
• To explore the catalytic mechanisms involved using experimental and theoretical methods.

Main Methods:

• Experimental investigation of CH4 oxidation in CO2-rich environments over Pd catalysts.
• Density-functional theory (DFT) calculations to elucidate reaction pathways and surface interactions.

Main Results:

• Complete CH4 oxidation was achieved with no observed side-products.
• The rate of CO2 generation increased monotonically with higher CO2 feed concentrations.
• DFT calculations revealed that high CO2 surface coverage lowers activation energies for CH4 dissociation and oxidation.

Conclusions:

• CO2-rich atmospheres are beneficial for enhancing O2 removal efficiency in oxy-combustion exhaust.
• The study provides mechanistic insights into CO2-promoted O2 removal over Pd catalysts.
• Findings support the improved purification of CO2 streams for subsequent utilization.