Abstract:
Binuclear metal complexes of copperand cobaltwere supported as sub
monolayer, monolayer and multilayer films on silica (Cab-O-Sil). The
supported metal complexes were characterized by elemental analyses,
DRIFTS, XRD and TGA. Elemental analysis results confirmed that the
carbon/metal ratio of the supported complexes was the same as the parent
metal complexes. Upon adsorption, certain IR peaks of the parent metal
complexes were shifted indicating the strong interaction between the metal
complex and the silica support. Metal complex loadings were monitored by
UV-vis spectroscopy and confirmed by TGA and elemental analysis. After
calcination, monolayer and multilayer films were used as catalysts for the
Fischer-Tropsch (FT) reaction (conversion of CO and H2 to gasoline) at
moderate temperatures and high pressures. Total CO conversions and
gasoline yields were studied as a function of time of syngas on stream (15-75
h), temperature (310, 320 and 350˚C), and total pressure (750 and 910 psi).
The product distribution of multilayer catalyst differed with extended
reaction time on stream, temperature and pressure. C4+ hydrocarbon
selectivity significantly increased with a 70 h reaction time. This suggests
that extended reaction times give enough time for short chain hydrocarbons
to grow into long chain hydrocarbons. After a 70 h reaction time, CO2
selectivity decreased dramatically. An increase in temperature also increased
the C4+ hydrocarbon selectivity. 910 psi pressure reaction conditions also
shifted the FT reaction to the product side. The C4+ product selectivity was
improved by the 910 psi pressure reaction conditions.
