Explosion-like Redispersion via Ejection of "Hot Molecules" In Situ Generated by Exothermic Reaction.

Area of Science:

• Catalysis Science and Engineering
• Materials Chemistry
• Chemical Reaction Engineering

Background:

• Efficient redispersion of metal catalysts is vital for industrial applications, but challenging for high-loading catalysts due to limited anchoring sites.
• Current redispersion methods lack molecular-level understanding and struggle with efficiency.

Purpose of the Study:

• To discover and detail a new redispersion mechanism for metal catalysts.
• To understand the molecular-level processes driving unconventional redispersion.
• To develop a highly efficient method for preparing high-loading catalysts.

Main Methods:

• Investigated the reaction of Molybdenum Dioxide (MoO2) with Oxygen (O2) to induce redispersion.
• Utilized in-situ observation of an
• explosion-like
• redispersion pattern.
• Analyzed the formation and dispersion of mono- and multi-nuclear Molybdenum Oxide (MoxOy) clusters as
• hot molecules
• .

Main Results:

• Discovered an explosion-like redispersion pattern driven by an exothermic reaction between MoO2 and O2.
• Identified in-situ produced mono- and multi-nuclear MoxOy clusters as high-kinetic-energy
• hot molecules
• .
• Achieved uniform dispersion of subnano MoO3 species with up to ~36.7 wt% loading on carbon supports via metastable hexagonal MoO2.

Conclusions:

• The reaction-driven chemical redispersion is highly efficient and offers advantages over traditional physical methods.
• This work provides molecular-level insights into catalyst redispersion.
• Presents a pragmatic strategy for preparing highly efficient catalysts with significant industrial potential.