Reaction Dynamics of CO₂ Hydrogenation on Iron Catalysts Using ReaxFF Molecular Dynamics Simulation

Area of Science:

• Catalysis
• Materials Science
• Computational Chemistry

Background:

• Carbon dioxide (CO2) conversion to hydrocarbons offers sustainable chemical production.
• Iron-based catalysts show promise for CO2 hydrogenation.
• Catalyst performance, particularly selectivity and conversion, is sensitive to iron particle size.

Purpose of the Study:

• Investigate the impact of iron nanocluster size on CO2 hydrogenation reactivity.
• Understand the reaction mechanisms at the atomic level.
• Explore the utility of reactive molecular dynamics (ReaxFF-MD) for studying catalytic processes.

Main Methods:

• Employed reactive molecular dynamics (ReaxFF-MD) simulations.
• Simulated iron nanoclusters (Fe4, Fe16) and an Fe slab in a CO2 and H2 environment.
• Validated the ReaxFF model against Density Functional Theory (DFT) results for CO2 dissociation.

Main Results:

• The ReaxFF model accurately described homogeneous CO2 hydrogenation.
• CO2 dissociation mechanisms on Fe4, Fe16, and Fe slab matched prior DFT findings.
• Reactivity demonstrated a significant dependence on cluster size, with Fe4 exhibiting the highest activity.

Conclusions:

• ReaxFF-MD is a valuable tool for elucidating reaction mechanisms in complex, non-equilibrium catalytic systems.
• Iron nanocluster size critically influences CO2 hydrogenation efficiency.
• The Fe4 cluster is identified as a highly reactive species for CO2 conversion.