ELUCIDATION OF MECHANISM OF COAL-LIQUEFACTION USING TRITIUM AND S-35 TRACER METHODS

The reactivity of hydrogen in tetralin and in Taiheiyo coal in the pre sence of iron catalysts (pyrrhotite and iron pentacarbonyl (Fe(CO)(5)) ) and sulfur were investigated using tritium and S-35 tracer methods u nder liquefaction conditions. Coal liquefaction was performed for 30 m in at an initial pressure of 5.9 MPa and a temperature of 400 degrees C in the presence of tetralin solvent and tritiated hydrogen, with and without a catalyst and S-35-labeled sulfur. The rate of coal conversi on and the tritium distribution in coal were higher when Fe(CO)(5) and sulfur were used than were obtained with conventional pyrrhotite. Fur ther, the coal products obtained with the use of Fe(CO)(5) and sulfur were lighter than those produced in the presence of added pyrrhotite. The results suggest that the catalyst derived from Fe(CO)(5) and sulfu r was successfully dispersed in the coal and directly acted on the coa l to increase both the rate of coal conversion and the tritium transfe r from the gas phase to the coal. The iron catalysts greatly promoted the hydrogen exchange between the gas phase and the tetralin solvent i n the absence of coal. Part of the added sulfur participated in the su lfur exchange reaction with the pyrrhotite catalyst. The addition of s ulfur increased the amount of hydrogen incorporated into the coal. Thi s suggests that sulfur promoted the formation of tetralyl radicals dur ing the hydrogen transfer from the solvent to the coal.