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 heterogeneou s/homogeneous combination mode to selectively produce mixed (C-1-C-4) alcoh ols from syngas is described. The Fe particles were generated via complete decomposition of Fe(CO)(5) in Ethylflo-164 hydrocarbon solvent at 225 degre es C under N-2 in under 2 h. The resulting Fe particles, though somewhat ag gregated, averaged < 30 nm in mean particle diameter as determined by trans mission electron microscopy. On mixing this highly dispersed Fe slurry (0.3 -0.8 wt% Fe loading) with a strong base (0.4-0.8 M potassium alkoxide or po tassium hydroxide) dissolved in an oxygenated solvent, CO was hydrogenated at less than or equal to 250 degrees C and < 6 MPa to selectively (up to 95 %) yield C-1-C-4 alcohols over traditional hydrocarbons. Mossbauer measurem ents on quenched catalyst samples indicated that metallic and carbided Fe s pecies (48% Fe, 38% gamma-Fe5C2, 14% Fe3O4) predominated in the hydrocarbon product-selective catalytic reaction, and fully oxidized Fe species (45% F e2SiO4, 24% FeCO3, 22% Fe2O3, 9% Fe3O4) were observed under catalytic condi tions that predominantly yielded oxygenates. The implication of utilizing a n inexpensive Fe-based catalytic system consisting of a slurried Fe (hetero geneous) and dissolved base (homogeneous) that effects CO hydrogenation to preferentially yield C-1-C-4 mixed alcohols is discussed in relation to tra ditional base-doped Fe catalysts. (C) 1998 Elsevier Science Ltd. All rights reserved.