Methane activation by V3PO10(˙+) and V4O10(˙+) clusters: a comparative study.

Area of Science:

• Heteronuclear oxide cluster chemistry
• Surface science and catalysis
• Computational chemistry

Background:

• Vanadium and phosphorus oxide clusters are studied for catalytic applications.
• Methane activation is a key challenge in catalysis.
• Previous studies explored methane activation by V(4)O(10)(+) and P(4)O(10)(+) clusters.

Purpose of the Study:

• To investigate the reactions of V(3)PO(10)(+) and V(4)O(10)(+) clusters with methane.
• To compare the reactivity of heteronuclear (V(3)PO(10)(+)) and homonuclear (V(4)O(10)(+)) oxide clusters in methane activation.
• To elucidate the role of intra-cluster spin density transfer in methane activation using DFT calculations.

Main Methods:

• Laser ablation for cluster preparation.
• Fast flow reactor for gas-phase reactions.
• Time-of-flight mass spectrometry for cluster detection.
• Density functional theory (DFT) calculations for structural and electronic analysis.

Main Results:

• V(3)PO(10)(+) and V(4)O(10)(+) clusters react with methane via hydrogen atom abstraction.
• The reaction rate of V(4)O(10)(+) with methane is approximately 2.5 times faster than that of V(3)PO(10)(+).
• DFT calculations reveal that facile methane activation is linked to an oxygen-centered radical (O˙) and intra-cluster spin density transfer.
• Intra-cluster spin density transfer is efficient in high symmetry V(4)O(10)(+) and P(4)O(10)(+) clusters, but forbidden in low symmetry V(3)PO(10)(+).

Conclusions:

• The presence of an oxygen-centered radical is crucial for methane activation by these oxide clusters.
• The observed reactivity difference between V(4)O(10)(+) and V(3)PO(10)(+) is explained by the ease of intra-cluster spin density transfer.
• High symmetry in oxide clusters facilitates spin density transfer, enhancing methane activation efficiency.