SYNTHESIS OF HYDROCARBONS FROM CO AND H-2 ON SIO(2) SUPPORTED IRON-COBALT CLUSTERS

Bimetallic catalysts (Fe+Co)/SiO2 were prepared by impregnation of SiO 2 with solutions of carbonyl clusters [FeCo3(CO)12][(C2H5)4N], [Fe3Co( CO)13][(C2H5)4N], HFeCo3(CO)12, [Fe5CoC(CO)16][(C2H5)4N], and Co2(CO)8 , Fe(CO)5. At 20-degrees-C, no reaction occurs between the compounds s upported and the surface of the support. The stability of the supporte d clusters to thermodecarboxylation in a hydrogen atmosphere depends o n their composition and is the highest for the catalyst [FeCo3(CO)12]- /SiO2. The catalytic properties of supported clusters in CO hydrogenat ion are mostly determined by the preactivation technique. The properti es of Fe-Co catalysts which were pretreated at high temperatures, are in general similar to those of standard metal catalysts. Product distr ibution for the same samples prepared without preactivation does not f it the Schulz-Flory equation. The catalyst HFeCo3(CO)12/SiO2 favors th e formation of C1-C-11 hydrocarbons in the temperature range of 468-47 3 K; the catalyst [Fe3Co(CO)13]-/SiO2 gives ethylene in the temperatur e range of 453-473 K.