Comparative density functional study of methanol decomposition on Cu4 and Co4 clusters

Area of Science:

• Computational Chemistry
• Surface Science
• Catalysis

Background:

• Methanol decomposition is crucial for producing hydrogen and carbon monoxide.
• Understanding cluster catalysis requires detailed reaction mechanism studies.
• Previous work explored palladium clusters, necessitating comparison with other transition metals.

Purpose of the Study:

• To investigate methanol decomposition on Cu(4) and Co(4) clusters using density functional theory.
• To determine reaction intermediates and activation barriers for H(2) and CO formation.
• To compare the catalytic activity and poisoning potential of Cu and Co clusters.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Analysis of reaction pathways involving C-H, O-H, and C-O bond cleavage.
• Determination of activation energies and reaction energies for key steps.

Main Results:

• Cu(4) favors methanol dehydrogenation via CH(2)OH, CHOH, CHO intermediates.
• Co(4) favors methanol dehydrogenation via CH(3)O, CH(2)O intermediates, showing favorable kinetics.
• Cobalt clusters exhibit strong CO binding, leading to potential low-temperature poisoning; copper clusters do not.
• C-O bond cleavage pathways are energetically unfavorable for both clusters.
• A linear Brønsted-Evans-Polanyi relationship was observed across Pd, Cu, and Co clusters.

Conclusions:

• Cobalt clusters are kinetically and thermodynamically favorable for methanol dehydrogenation but susceptible to CO poisoning.
• Copper clusters are less prone to CO poisoning but exhibit less favorable dehydrogenation energetics.
• The findings provide insights into catalyst design for selective methanol conversion.