FINELY DISPERSED IRON, IRON MOLYBDENUM, AND SULFATED IRON-OXIDES AS CATALYSTS FOR COPROCESSING REACTIONS

We have recently reported on the catalytic activity of sulfated iron and tin oxides for the direct liquefaction of coal (Energy Fuels 1991, 5, 497-507) and on the activity of the soluble precursor, Fe(CO)5, for coprocessing of Illinois No. 6 coal with Maya ATB residuum (650-degrees-F+) (Energy Fuels 1990, 4, 231-237). This paper addresses the activity and characterization of finely dispersed iron-and molybdenum-containing catalysts based on the soluble precursors Fe(CO)5 and Mo(CO)6, and on the finely divided (average crystallite size of 30-80 angstrom) sulfated metal oxide superacids such as Fe2O3/SO42- and SnO2/SO42- for coprocessing reactions. The catalysts were characterized and tested for activity with various coals and Maya ATB heavy oil (650-degrees-F) in coprocessing reactions. The following catalyst-coal combinations are reported: Fe(CO)5 with three premium Argonne coals; Mo(CO)6 and Mo naphthenate with Illinois No. 6; mixtures of Fe(CO)5 and Mo(CO)6 with Illinois No. 6; sulfated iron and tin oxides with Illinois No. 6; and a new catalyst, Mo-promoted sulfated iron oxide, with Illinois No. 6 coal. The use of a newly synthesized bimetallic catalyst, Mo/Fe2O3/SO42-, consisting of 50 ppm Mo and 3500 ppm iron, gave a 78% conversion of illinois No. 6 coal to methylene chloride soluble products with a selectivity to oils of 80 wt % at 400-degrees-C. The following order of catalyst activity (the yield of n-pentane-soluble products is referred to here as "activity") was observed for coprocessing reactions carried out with Illinois No. 6 coal and Maya ATB oil at 400-degrees-C: Mo/Fe2O3/SO42- > Fe2O3/SO42-, Fe(CO)5/Mo(CO)6 > Mo(CO)6 > Fe(CO)5. The addition of elemental sulfur to the coal-oil mixture prior to the coprocessing reactions did not show any notable effect on conversions. Both hydrodenitrogenation (approximately 40%) and hydrodesulfurization (approximately 60%) were obtained with iron-molybdenum bimetallic catalysts based on sulfated oxides. We believe that the sulfate group in these catalysts helps to prevent sintering or agglomeration of catalysts at high temperatures. The high surface acidity of the catalyst may influence the nature of the reactions that occur in the early stages of coprocessing reactions but the catalyst activity is mainly due to the easy accessibility of the dissolved coal, heavy oil, and H2 to the small catalyst particles.