SURFACE CHARACTERIZATION AND LIQUEFACTION OF IRON-IMPREGNATED AND MOLYBDENUM-IMPREGNATED SUBBITUMINOUS COAL

Results are presented from a study of the preparation and characteriza tion of Wyodak subbituminous coal impregnated with iron and iron-molyb denum salts by the incipient wetness (IW) technique. X-ray photoelectr on spectroscopy (XPS) was used to examine the surface composition and chemistry of coals impregnated with 0.7-2.0 wt % Fe and 500-1000 ppmw Mo. Various salts were used in preparing the impregnated coals includi ng ferric nitrate, ferric sulfate, ferrous sulfate, and ammonium molyb date. The surface concentration of Fe increased as the amount of added Fe increased, with higher concentrations being observed for the nitra te-impregnated coals. The anions of the impregnating salts were readil y removed from the samples that were treated with ammonium hydroxide s olution. For samples impregnated with sulfate salts, which were not tr eated with base, higher sulfur concentrations were observed on the sur face of the coal. The Fe-2p32 and Fe-3p peak positions in the base tre ated coals correspond with alpha-FeOOH while the positions in the non- base-treated sulfate-impregnated coals are consistent with the Fe sulf ate salts. The added Fe on the surface of the impregnated coals has a direct impact on the position of the O-1s peak shifting it to a lower energy position. Overlap of the Mo-3d doublet by the S-2s peak require d deconvolution based upon peak positions in reference materials. The liquefaction performance of the impregnated samples is directly relate d to the amount of added Fe with THF conversion and oil yield increasi ng as Fe concentration on the surface increased. The liquefaction resu lts with the Fe-Mo co-impregnated coals were better than the other coa ls prepared in this study.