Mesoscale Structures in the Adlayer of A-B₂ Heterogeneous Catalysis

Area of Science:

• Chemical Engineering
• Surface Science
• Computational Chemistry

Background:

• Understanding adsorbate distributions is crucial for optimizing heterogeneous catalysis.
• Previous studies on the A-B model provide a baseline for comparison.
• The A-B2 system introduces unique adsorption/desorption behaviors and reaction stoichiometry.

Purpose of the Study:

• To investigate adsorbate distributions in a model A-B2 heterogeneous catalysis system.
• To compare the influence of kinetic processes (adsorption, desorption, diffusion, reaction) on adlayer structure.
• To identify novel features introduced by the B2 species compared to the A-B model.

Main Methods:

• Kinetic Monte Carlo (KMC) simulations were employed.
• The model system A + 1/2B2 → AB was simulated.
• Analysis focused on adsorbate distributions and the impact of kinetic parameters.

Main Results:

• Desorption and diffusion contribute to adlayer uniformity, while reactions cause clustering.
• Desorption has a stronger homogenizing effect than diffusion in the A-B2 system, contrary to the A-B model.
• Different kinetic rate constants can lead to distinct dominant species at steady states.
• The B species poisoning regime shrinks, expanding the coexisting regime.

Conclusions:

• The A-B2 system exhibits unique adsorbate distribution characteristics due to the nature of B2 adsorption/desorption and reaction stoichiometry.
• Kinetic processes significantly influence adlayer structure, with desorption being a dominant factor in homogenization.
• The findings offer insights into controlling surface phenomena in heterogeneous catalysis.