Thermal decomposition of the supported clusters [HFe3(CO)11]-/MgO and Fe3(CO)12/MgO results in heterogeneous catalysts which are selective for low molecular weight olefins in the Fischer-Tropsch synthesis. Characterization of the metal particles resulting from such decomposition has been carried out by using IR, ferromagnetic resonance (FMR), Mössbauer, magnetism, and gas-phase analysis. The results depend on the state of dehydration of the support: on highly hydrated magnesia (MgO 25), [HFe3(CO)11]-Mg+ undergoes an electrophilic attack by surface protons with formation of a significant amount of Fe2+ and H2 which makes difficult the characterization of zerovalent iron. On highly dehydrated magnesia (MgO 400), thermal decomposition of the supported Fe3(CO)12 is irreversible and the zerovalent iron is not oxidized by surface protons. During the decarbonylation process the iron agglomerates into a superparamagnetic particle of zerovalent iron covered with dissociated CO.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry