| Hydrocarbon reactions catalyzed by transition metals occur in many petrochemical processes. In these processes C-H and C-C bonds are formed and disrupted. Similar processes are present in the Fischer-Tropsch synthesis, in which hydrocarbons, olefins and oxygenates are formed out of synthesis gas (a mixture of hydrogen and carbonmonoxide).; The thesis deals with a theoretical investigation of important elementary steps of the Fischer-Tropsch synthesis and hydrocarbon conversion reactions. In this study are used the Extended Huckel and the Atom Superposition and Electron Delocalization (ASED) Molecular Orbital methods.; The reaction step examined first is the adsorption of C, O and CO. A detailed analysis is made which electronic interactions are responsible for the relative stability of CO as a function of adsorption geometry (linear, bridge, hollow) and as a function of single crystal plane ( (111), (100) and (110)).; The step studied next is the dissociation of CO. The most probable reaction path of dissociation is found by a comparison of a great number of possible reaction paths for the (100), (110), stepped and nonstepped (111) planes of Rh. A general mechanism is proposed, in which CO in an transition state is bonded to an extra surface Rh atom. The calculations allow to predict the metal ensemble necessary for the dissociation reaction.; In a final chapter the adsorption and reactivity of CH{dollar}sb{lcub}rm x{rcub}{dollar} (x = 1-3) on Rh(111) and Ni(111) are studied. The relative stability of Ch{dollar}sb{lcub}rm x{rcub}{dollar} fragments and the recombination of these fragments into hydrocarbon chains are discussed. Important is the relative contribution of metal d electrons. |
