Low-Temperature Methane Combustion Using Ozone over Coβ Catalyst.

Area of Science:

• Catalysis
• Materials Science
• Environmental Chemistry

Background:

• Unburned methane (CH4) emissions contribute to greenhouse gases.
• Catalytic combustion is a key strategy for mitigating CH4 release.
• Ozone (O3) activation offers a novel pathway for low-temperature methane oxidation.

Purpose of the Study:

• To develop an efficient catalyst for low-temperature methane combustion.
• To identify the active sites and reaction mechanism of methane oxidation.
• To evaluate the catalyst's stability and performance under various conditions.

Main Methods:

• Synthesis and characterization of ion-exchanged β zeolites (Co, Ni, Mn, Fe, Pd).
• Catalytic activity testing for methane combustion using ozone.
• X-ray absorption spectroscopy (XAS) to determine active species.
• Single-component artificial force-induced reaction (SC-AFIR) calculations for mechanism elucidation.

Main Results:

• Co-exchanged β zeolite (Coβ) demonstrated superior performance below 100 °C.
• Isolated Co2+ species were identified as the primary active sites.
• Theoretical calculations revealed a reaction pathway with a 73 kJ/mol activation energy.
• Catalyst activity decreased in the presence of H2O and CO but recovered after dehydration.

Conclusions:

• Isolated Co2+ in β zeolite is an effective catalyst for low-temperature methane combustion with ozone.
• The reaction proceeds via a mechanism supported by theoretical calculations.
• The catalyst exhibits good stability and regenerability, though sensitive to water and carbon monoxide.