Pd nanocatalysts engineering for direct oxidation methane-to-methanol with 99.7% selectivity

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Palladium (Pd) catalysts are active for direct oxidation methane-to-methanol (DOMM).
• Complex polycrystalline structures hinder understanding of Pd catalyst structure-performance relationships.
• Well-defined Pd nanocrystals are needed as model systems to study structure-activity differences.

Purpose of the Study:

• To investigate the origins of structure-activity differences in Pd catalysts for DOMM.
• To correlate nanocrystal morphology with catalytic performance in DOMM.
• To elucidate the role of crystal facets in DOMM selectivity and activity.

Main Methods:

• Synthesis of well-defined Pd nanocrystals with controlled morphologies.
• Utilizing these nanocrystals as model systems for DOMM reactions.
• Analyzing the relationship between crystal facet type and catalytic activity.

Main Results:

• DOMM activity is governed by crystal facet type, not nanocrystal size.
• The Pd {111} facet's lower d-band center weakens adsorption of key intermediates (*O2 and *OH).
• {111}-dominated octahedral Pd nanocrystals yield 201.8 mmol·gPd−1·h−1 methanol, three times higher than {100}-dominated counterparts.

Conclusions:

• Crystal facet engineering is crucial for optimizing Pd catalysts in DOMM.
• Pd {111} facets promote efficient methanol production by modulating intermediate adsorption.
• This study provides insights for designing superior Pd catalysts for direct oxidation methane-to-methanol.