Cooperative research in coal liquefaction. Final report, May 1, 1992--April 30, 1993

Abstract

One step in the synthesis of anion-treated iron and tin oxides is precipitation as hydroxides using either urea or ammonium hydroxide. The catalysts prepared using urea as a precipitation agent were more reproducible than those using ammonium hydroxide in terms of activities and properties. These catalystdcatalyst precursors were characterized by several techniques to determine their physical (size and structure related) and chemical (acidity) properties. Sulfated and mo€ybdated iron oxides were found to have grain sizes as small as 10-20 nm. An attempt was made to correlate the physicochemical properties of these catalysts with their activity for coal liquefaction. SiIron ion-exchanged into lignite from an iron Acetate solution showed excelle activity for direct coal liquefaction. Two lignites were studied, and both exhibite significant increases in both total conversion and oil yields when from 1 t o 7% of ir was incorporated into the coal by cation-exchange. Mossbauer spectroscopy and 0th characterization methods indicated that a substantial percentage of the iron was present in particles o r molecular complexes less than 30 A in diameter. 4An investigation of catalyst dispersion has been made using electron probe microanalysis (EPMA) following impregnation of Wyodak coal with FeC1, and (NH4)2hbS4 in aqueous solutions. Before hydrotreatment, the iron and molybdenum are found coating the coal particles. After hydrotreatment at 350°C and 1500 psig H2, both the Fe and Mo are dispersed throughout the interior of the coal particles.Design, construction and testing of a batch-type tubing bomb microreactor has been completed in the liquefaction laboratory at West Virginia University. Tests of the variation in liquefaction yields for Blind Canyon coal as a function of time, temperature, and agitation speed have been completed. A second system, which is similar in design, but incorporates a hydrogen purge, associated gas preheat and downstream product analysis, has also been designed and constructed. Testing of this system is now in progress.Reaction of ferric chloride at 5°C with sodium sulfide in aqueous solution yielded a black colloid of Fez& On heating to 100 -200"C, the ferric sulfide disproportionates to pyrite, pyrrhotite, and elemental sulfur. Particle sizes of the iron sulfides produced by this method are typically around 200 A. These iron sulfides exhibit reasonable catalytic activity for DCL of Blind Canyon coal at 350"C, increasing total conversion by about lo%, split approximately between increases in asphaltene and oil + gas yields. At 400°C, however, the catalytic conversion and yields are only slightly hig,her than those observed thermally for the DECS-17 coal.A novel aerosol reactor for generation of ultrafine iron sulfide catalysts has been designed and is now under construction.In situ transmission electron microscopy (TEM) studies were carried out to elucidate the basic mechanisms of the catalytic reaction between hydrogen and graphite in the presence of either iron sulfide or molybdenum sulfide...