Oxidative Methane Conversion to Ethane on Highly Oxidized Pd/CeO₂ Catalysts Below 400 °C

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Methane upgrading to valuable chemicals is crucial for energy and chemical industries.
• Low-temperature methane conversion remains a significant challenge.

Purpose of the Study:

• To report oxidative methane conversion to ethane at low temperatures (<400°C) and atmospheric pressure.
• To identify the active sites responsible for selective ethane production.

Main Methods:

• Utilized a continuous reactor for methane upgrading.
• Employed palladium (Pd) deposited on ceria (CeO₂) as a catalyst.
• Performed density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• Achieved high ethane productivity (0.84 mmol g_cat⁻¹ h⁻¹) using a highly oxidized Pd/CeO₂ catalyst.
• Identified Pd-O-Pd sites as the active centers for low-temperature ethane production, not Pd-O-Ce sites.
• DFT calculations confirmed Pd-O-Pd sites favor C-C coupling, while Pd-O-Ce sites promote methane dehydrogenation.
• Ceria stabilized the highly oxidic state of Pd under reductive methane flow.

Conclusions:

• Pd-O-Pd sites are key for selective, low-temperature methane-to-ethane conversion.
• The Pd/CeO₂ catalyst system offers a promising route for methane upgrading.
• This research provides insights into designing catalysts for C₂ production from methane.