RELATIVE ACTIVITY OF NANOSCALE IRON-OXIDE, IRON CARBIDE, AND IRON SULFIDE CATALYST PRECURSORS FOR THE LIQUEFACTION OF A SUBBITUMINOUS COAL

Three nanoscale iron-based catalyst precursors were tested to determin e their effect on the conversion of a subbituminous coal. The results of this study indicate that each of the precursors, superfine iran oxi de, Fe7C3, and Fe1-xS, exhibited very similar activity and selectivity with only minor variations. However, the hydrogenation activities of the three catalysts were very different. This was related to the parti cle size and surface area of the precursor, rather than its phase. The insensitivity to phase was probably due to the rapid transformation o f the precursor surface, where the catalytic reaction occurs, to a sim ilar structure in each case. The increase in hydrogen consumption with out corresponding increases in conversion indicates that bond cleavage , rather than availability of labile hydrogen, was the rate limiting s tep in the coal liquefaction reaction.