화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.114, No.45, 14458-14466, 2010
Comparative Density Functional Study of Methanol Decomposition on Cu-4 and Co-4 Clusters
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 (CH2OH), 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 (CH3O) and formaldehyde (CH2O) 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, Bronsted-Evans-Polanyi plot