Selective synthesis of mixed alcohols catalyzed by dissolved base-activated highly dispersed slurried iron

An ultrafine Fe metal-based catalyst system that operates in a heterogeneous/homogeneous combination mode to selectively produce mixed (C₁-C4) alcohols from syngas is described. The Fe partieles were generated via complete decomposition of Fe(CO)₅ in Ethylflo-164 hydrocarbon solvent at 225°C under N₂ in under 2 h. The resulting Fe particles, though somewhat aggregated, averaged < 30 nm in mean partide diameter as determined by transmission electron microscopy. On mixing this highly dispersed Fe slurry (0.3-0.8wt% Feloading) with a strong base (0.4-0.8 M potassium alkoxideor potassium hydroxide) dissolved in an oxygenated solvent, CO was hydrogenated at < 250°C and < 6MPato selectivay (up to 95%) yi ad C₁-C₄ alcohols over traditional hydrocarbons. Mössbauer measurements on quenched catalyst samples indicated that metallic and carbided Fe species (48% Fe, 38% 7-Fe₃O₄, 14% Fe₃O₄) predominated in the hydrocarbon product-selective catalytic reaction, and fully oxidized Fe species (45% Fe₂SiO₄1, 24% FeCO₃, 22% Fe₂O₃, 9% Fe₃O₄) were observed under catalytic conditions that predominantly yielded oxygenates. The implication of utilizing an inexpensive Fe-based catalytic system consisting of a slurried Fe (heterogeneous) and dissolved base (homogeneous) that effects CO hydrogenation to preferentially yield C₁-C₄ mixed alcohols is discussed in relation to traditional base-doped Fe catalysts.