COAL TIRE COLIQUEFACTION USING AN IRON SULFIDE CATALYST IMPREGNATED IN-SITU IN THE COAL

The coliquefaction of coal with discarded tire rubber is studied at 1000 psig (cold) of hydrogen and 400 degrees C using a hva bituminous coal in the presence of an impregnated iron sulfide catalyst, without addition of a sulfiding agent. The base case is a noncatalytic coliquefaction under the same conditions. The catalyst shows activity comparable to other catalysts commonly used for direct coal liquefaction (DCL) under the conditions used here. The values of the conversion and yield, when using the tire as solvent, differ from the corresponding values when a facile hydrogen-donating solvent such as tetralin is used. However, these differences diminish in the presence of the iron sulfide catalyst, under the conditions studied. Even at Fe levels as low as 1100 ppm in coal, the catalyst greatly improves the coal conversion, from 44% (in the base case) to 60%. The liquefaction rate is first-order dependent on the catalyst loading and first-order dependent on the rubber tire loading. Impregnation of the total amount of catalyst on only 12% of feed coal (to the reactor) achieves the same coal conversion as when 100% of the feed coal is impregnated with the same total amount of catalyst. This is significant because it implies that only a small fraction of the feed coal in a large-scale operation needs to be subjected to the catalyst impregnation process. The presence of the byproduct sodium chloride from the formation of the iron sulfide catalyst does not significantly affect catalyst performance. This is a significant result because it implies that extremely rigorous washing of the impregnated coal is not essential for commercial-scale operation of this process.