Comparative Density Functional Study of Methanol Decomposition on Cu₄ and Co₄ Clusters

Abstract

A density functional theory study of the decomposition of methanol on Cu(4) and Co(4) clusters is presented. The reaction intermediates and activation barriers have been determined for reaction steps to form H(2) and CO. For both clusters, methanol decomposition initiated by C-H and O-H bond breaking was investigated. In the case of a Cu(4) cluster, methanol dehydrogenation through hydroxymethyl (CH(2)OH), hydroxymethylene (CHOH), formyl (CHO), and carbon monoxide (CO) is found to be slightly more favorable. For a Co(4) cluster, the dehydrogenation pathway through methoxy (CH(3)O) and formaldehyde (CH(2)O) is slightly more favorable. Each of these pathways results in formation of CO and H(2). The Co cluster pathway is very favorable thermodynamically and kinetically for dehydrogenation. However, since CO binds strongly, it is likely to poison methanol decomposition to H(2) and CO at low temperatures. In contrast, for the Cu cluster, CO poisoning is not likely to be a problem since it does not bind strongly, but the dehydrogenation steps are not energetically favorable. Pathways involving C-O bond cleavage are even less energetically favorable. The results are compared to our previous study of methanol decomposition on Pd(4) and Pd(8) clusters. Finally, all reaction energy changes and transition state energies, including those for the Pd clusters, are related in a linear, Brønsted-Evans-Polanyi plot.

Methanol activation catalyzed by Pt7, Pt3Cu4, and Cu7 clusters: A density functional theory investigation

“…We find that, there is a linear relation between the E TS and E FS , which conforms to Brønsted‐Evans‐Polanyi (BEP) relation . The obtained result is shown in Figure in detail, and this linear relation has been found in many investigations . It is important to note that the zero energy reference for each step is the clean cluster plus gas phase energy of the corresponding reactants.…”

“…Reducing the size of cluster can accelerate catalyzed ability, because nanosized cluster can produce tremendous improvements in catalyzed performance due to its large surface area . Up to now, numerous experimental and theoretical studies focused on the cluster catalysts for methanol dissociation . Binary metal clusters have unique characters due to their unique structures.…”

“…[38] Widely known as excellent catalyst for methanol dissociation reactions, cluster were also considered as crucial agent. [39] Reducing the size of cluster can accelerate catalyzed ability, because nanosized cluster can produce tremendous improvements in catalyzed performance due to its large surface area. [40][41][42] Up to now, numerous experimental and theoretical studies focused on the cluster catalysts for methanol dissociation.…”

“…[40][41][42] Up to now, numerous experimental and theoretical studies focused on the cluster catalysts for methanol dissociation. [39,[43][44][45][46][47] Binary metal clusters have unique characters due to their unique structures. The electronic, magnetic, and reactivity properties will change with the number of atoms and composition.…”

N2O dissociation on small Rh clusters: A density functional study

“…A first step in the understanding of the catalytic activity for the N 2 O decomposition reaction, requires the knowledge of the energetically most stable adsorption sites of the reactant and products and the most favorable decomposition reaction pathways [10]. In this contribution, we systematically investigate the interaction between N 2 O and Rh 1-6 clusters using the first principles methods on the basis of DFT.…”