Selective Oxidation of Propylene on Cu₂O(111) and Cu₂O(110) Surfaces: A Systematically DFT Study

Area of Science:

• Surface science
• Catalysis
• Computational chemistry

Background:

• Selective oxidation of propylene is crucial for producing valuable chemicals.
• Understanding reaction mechanisms on different copper oxide crystal facets is key for catalyst optimization.
• Previous studies have explored propylene oxidation, but crystal plane effects require further investigation.

Purpose of the Study:

• To investigate the selective oxidation of propylene on Cu2O(111) and Cu2O(110) surfaces using density functional theory.
• To elucidate the reaction mechanisms and identify the factors controlling product selectivity.
• To provide insights for designing catalysts with high selectivity for specific products like propylene oxide (PO).

Main Methods:

• Density functional theory (DFT) calculations with a Hubbard U correction.
• Analysis of reaction pathways including allylic hydrogen stripping and epoxidation via oxametallacycle intermediates.
• Energetic span model analysis to determine rate-determining steps and confirm kinetic favorability.

Main Results:

• Cu2O exhibits significant crystal plane-controlled selectivity in propylene oxidation.
• On the Cu2O(111) surface, acrolein is the main product due to kinetically favorable pathways.
• On the Cu2O(110) surface, propylene oxide (PO) is the favored product due to a high activation barrier for acrolein formation.

Conclusions:

• The crystal plane of Cu2O plays a critical role in determining the selectivity of propylene oxidation.
• The (111) surface favors acrolein production, while the (110) surface promotes PO formation.
• This study offers guidance for designing specific Cu2O crystal facets to achieve high selectivity and activity for desired products in propylene oxidation.