HETEROATOM ELIMINATION IN THE HYDROGENATION PROCESS OF BROWN COAL DERIVED LIQUIDS

Abstract

This chapter describes the heteroatom elimination in the hydrogenation process of brown coal derived liquids. The processes of fast low-temperature pyrolysis of brown coal provide relatively large amounts of liquid products. These products might be used as raw materials for production of syncrude oil. Low temperature tars obtained from Polish brown coals Turow and Konin contain comparatively large amounts of heteroatoms, especially oxygen, and some solid and mineral components. Upgrading process of this type raw material consists of the initial stage of solid and mineral components removal and the catalytic stage of heteroatoms elimination. In a study described in the chapter, the initial operations were carried out by solvent deashing or by vacuum distillation. The effect of process temperature, pressure, and liquid space velocity on sulfur, nitrogen, and oxygen removal rates was tested in the catalytic stage. No significant differences in the effect of the operation conditions upon the heteroatom elimination rates from the deashed and distilled tar were observed during the operation periods of the catalysts used. Hydrogen pressure significantly effects nitrogen elimination rate; however, its effect is smaller for sulfur or hydroxyl oxygen elimination rates.