Tailored Platinum Group Metal/Spinel Oxide Catalysts for Dynamically Enhanced Methane Oxidation

Area of Science:

• Materials Science
• Catalysis
• Environmental Science

Background:

• Growing demand for natural gas vehicles (NGVs) and engines (NGEs) to reduce CO2 emissions.
• Uncombusted methane from NGVs/NGEs is a potent greenhouse gas (GHG).
• Platinum group metals (PGM) and spinel oxides are key components in methane oxidation catalysts.

Purpose of the Study:

• To identify novel spinel oxides that enhance methane oxidation activity with PGMs.
• To correlate spinel oxide reducibility with catalytic performance for methane conversion.
• To reduce greenhouse gas emissions from natural gas applications.

Main Methods:

• Employed density functional theory (DFT) to screen earth-abundant, cobalt-rich spinel oxides.
• Calculated bulk oxygen vacancy formation energy (E_vac) to predict reducibility.
• Experimentally tested DFT-identified spinel oxides with Pt+Pd for methane oxidation activity.

Main Results:

• DFT identified several spinel oxides with favorable E_vac, correlating with dynamic oxygen storage capacity (DOSC).
• Experimental methane oxidation tests showed good agreement with DFT-predicted reducibility.
• NiCo2O4 exhibited the highest DOSC and lowest light-off temperature (T50), confirming computational predictions.

Conclusions:

• Spinel oxide reducibility is crucial for effective low-temperature methane conversion.
• A synergistic effect between PGM and spinel oxides enhances methane activation and oxidation.
• The study provides a pathway for designing efficient catalysts to mitigate GHG emissions.