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)6, for coprocessing of Illinois No. 6 coal with Maya ATB residuum (650 °F+) (Energy Fuels 1990, 4, 231-237). This paper addresses the activity and characterization of finely dispersed ironand 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 A) sulfated metal oxide superacids such as Fe203/S042_ and Sn02/S042' for coprocessing reactions. The catalysts were characterized and tested for activity with various coals and Maya ATB heavy oil (650 °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)6 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/Fe203/S042", 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 °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 °C: Mo/ Fe203/S042' > Fe203/S042", 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 (-40 %) and hydrodesulfurization (-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.

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In the Alcoa smelting process, anhydrous aluminum chloride is electrolytically converted to aluminum metal. This process could have a major impact on the aluminum industry if an efficient way of making the anhydrous aluminum chloride from alumina were found (Othmer et al., 1978). To make aluminum chloride, carbon and chlorine must be added to alumina. The carbon and chlorine reactants can take many forms, but carbon tetrachloride is convenient in that the carbon and chlorine are together in a single molecule. The net reaction is written as:The kinetics of this reaction have received considerable attention but the rates of the reaction have been too slow to justify industrial development.In this study, means of increasing the reaction rate by operating at supercritical conditions are experimentally investigated. The reaction product, AlCl,, is soluble in the supercritical reactant, and the solubility enhancement that supercritical fluids display is a reasonable explanation for the increases in the observed rate, which are reported. Experimental ProcedureAlumina, 5-10 g, solid, and excess carbon tetrachloride, 30-60 g, liquid, were combined in a batch reactor and heated rapidly to reaction conditions. Pressures of 4 to 10 MPa and temperatures of 563 to 643 K were supercritical with respect to carbon tetrachloride (T, = 283"C, P, = 4.5 MPa) and were monitored continuously. Conversions were determined by extracting the reaction products with water and measuring the amount of unconverted alumina. Alumina is the only water-insoluble solid in the reactor. At the conditions studied, particle size (mass average dia. 60 pm, number average dia. 6 pm N, BET surface area 60 m'/g) and the total mass of alumina charged had no effect on the reaction rate per unit mass and hence fluid-solid mass transfer is considered to be unimportant in the overall reaction rate process. Runs with smaller particles produced no increase in the reaction rate, which indicates that internal mass transfer limitations are not important.Reaction rates were measured by dividing the amount of alumina converted by the isothermal reaction time. A correction was made for the conversion during the heat-up period using the measured activation energy. This correction was verified experimentally by stopping several runs as soon as run temperature was reached. These runs yielded 1 to 5% conversion during heatup. Conversions ranged from 6 to 48% except for one high-temperature run where the conversion reached 73%. In addition, the assumption of irreversibility of the reaction for these conversions was verified by two runs showing very high conversion (88%) as run time was lengthened to 4 h. Results and DiscussionThe results obtained in this study are summarized in Figure 1, which also shows, under noncritical conditions, the results of previous investigators (Bertoti et al., 1980(Bertoti et al., , 1982. The primary difference between the present results and those of previous investigators is that the present experiments were conducted at much higher pressures (d...