ROLE OF TRANSITION-METAL OXIDES IN METAL DUSTING - DENSITY-FUNCTIONALSTUDY

Density function theory was applied to study the mechanisms and energe tics of two major metal dusting processes represented by Boudouard and steam-carbon reactions on the FeO(100) surface. Cluster models were u tilized to represent the surface. The chosen cluster model was validat ed by examining CO adsorption binding energies on clusters of various sizes. We show that the lattice relaxation has a relatively small effe ct on the adsorption. The reaction process involving direct abstractio n of O from the surface bq CO was excluded from consideration of the o verall dusting processes due to unfavorable energetics. Minimum energy path calculations were carried our to investigate the reaction mechan isms. It was found that both the Boudouard and steam-carbon reactions are thermochemically and kinetically, unfavorable on transition metal oxide surfaces. Detailed insight into the reaction mechanisms was obta ined by following the reaction trajectories and analyzing the electron population distribution along the reaction paths. This study elucidat es the empirical observation that metal oxide can often minimize metal dusting.