Influences of Exchanged Metal Ions on Coal Liquefaction

To clarify the effectiveness of ion exchange as a method of loading liquefaction catalysts, a subbituminous coal and three brown coals were loaded with iron catalysts by ion exchange, impregnation, or physical mixing and liquefied in a laboratory scale small autoclave. For Yallourn coal from Australia, the liquefaction yields of the iron-exchanged coal with added sulfur as promoter were higher than that of coals loaded by impregnation and physical mixing methods. For this coal, the amount of exchanged iron could be enhanced by a calcium preexchange treatment, leading to a further increase in liquefaction yields. In the cases of the other coals, the activities of the exchanged iron catalysts were nearly the same or lower than those of the pyrite powder physically mixed with coal. To explain this result, it is necessary to consider the fact that these coals have a small amount of cation exchange capacity and the exchanged iron is not act as effective as the same amount of the pyrite powder. Thus, the effect...