Detecting Framework Distortions Predicted by Hybrid-DFT: An Opportunity to Improve the M1 Catalyst

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• MoVNbTe-oxide catalysts are crucial for oxidative dehydrogenation and partial oxidation reactions.
• Understanding the atomic structure of these catalysts is key to optimizing their performance.
• Previous theoretical studies predicted distortions in active sites.

Purpose of the Study:

• To experimentally investigate the atomic structure of MoVNbTe-oxide catalysts using advanced imaging techniques.
• To correlate structural features with catalytic activity and selectivity.
• To validate theoretical predictions regarding active site distortions.

Main Methods:

• Scanning transmission electron microscopy (STEM) for high-resolution imaging of catalyst structure.
• Hybrid density functional theory (DFT) calculations to model atomic interactions and distortions.
• Analysis of anisotropic scattering projections to identify atom column arrangements.

Main Results:

• STEM imaging revealed anisotropic scattering projections of Mo and V atom columns, visualizing the catalytically active S2 site.
• Experimental observations confirmed predicted distortions of S2 sites toward hexagonal channels.
• Controlled partial occupancy of tellurium-oxide chains in hexagonal channels was achieved.

Conclusions:

• The controlled removal of [TeO]2+ entities and partial occupancy of (TeO) chains in hexagonal channels are critical for catalyst performance.
• These structural modifications introduce polarons, significantly enhancing catalytic reactivity and selectivity.
• The findings provide a pathway for designing more efficient MoVNbTe-oxide catalysts.