The catalytic hydrodenitrogenation (HDN) reactivities of coal liquid fractions (kerosene, light and heavy oils) were examined at 400 degree C under hydrogen pressure (approx. 200 atm) using a commercial nickel-molybdenum catalyst (Sphericat. 502). The structural analyses of coal liquids indicated that nitrogen were present in mono- and bi-cyclic aromatics in the kerosene and the light oil, whereas in tricyclic or larger aromatics in the heavy oil. Such structural differences may result in the different reactivities. The heavy oil was further divided into acidic, basic and neutral fractions to study their respective reactivities. The structural analyses of the hydrotreated heavy oil suggest that insufficient hydrogenation of the aromatic rings including the heterocyclic part under the present conditions is a reason for the low reactivity of heavy oil.
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