First-stage direct liquefaction of a subbituminous coal with oil-soluble metal naphthenates as dispersed catalyst precursors

Abstract

The activities of catalysts produced from Mo, Co and Fe naphthenate oil-soluble precursors were investigated and the particle size and crystalline phase of each metal sulfide from each metal precursor were determined by SEM-EDX, TEM and XRD. Also, the synergistic effect between Fe and Co or between Fe and Mo in the hydroliquefaction of Usibelli (Alaska) subbituminous coal was investigated. In catalytic liquefaction experiments, excess elemental sulfur (three times the stoichiometrically required amount to convert the metal to the respective sulfide form: FeS 2, Co 9S 8 and MoS 2) was added to produce highly dispersed metal sulfide catalysts in situ. Parametric continuous unit tests were carried out to verify the reproducibility of the batch microautoclave results and to gather enough sample for further quantitative analyses of the coal liquid products (distillate yields and H/C atomic ratio). The hydrogen pressure drop or relative hydrogen consumption followed the order Mo > Co > Fe. This trend gave good linear correlations with coal liquefaction yields (coal conversion and oil yield). It was confirmed that the addition of Co or Mo as a promoter to Fe as a primary component gave a synergistic effect on both coal liquefaction yields (coal conversion, oil yield and distillate) and H/C ratio of the liquid products.